0001193125-26-349168 | 10-Q | XBRL Viewer

Depreciation and amortization expense

$ 600

$ 200

$ 1,200

$ 1,300

Net loss

(52,463)

$ (45,316)

(34,810)

$ (38,326)

(97,779)

(73,136)

Operating Segments [Member]

Segment Reporting [Line Items]

Collaboration revenue

148

Other research and development expenses

8,319

7,462

15,969

14,034

Other general and administrative expenses

6,217

3,484

11,947

6,735

Depreciation and amortization expense

593

618

1,199

1,272

Stock-based compensation expense

3,634

823

4,938

1,675

Other segment items

^[1]

1,577

(1,710)

(560)

(3,625)

Net loss

(52,463)

(34,810)

(97,779)

(73,136)

Operating Segments [Member] | External research and development expense -Zolucatetide

Operating Segments [Member] | External research and development expense - Catenin Degrader

12,673

9,379

25,767

22,524

Operating Segments [Member] | External research and development expense ERG

799

193

1,215

912

Operating Segments [Member] | External research and development expense ARON [Member]

1,970

1,842

4,882

3,482

Operating Segments [Member] | Personnel-related research and development expenses

1,959

751

3,365

1,616

Other research and development expenses

11,362

8,471

21,594

17,609

Operating Segments [Member] | External research and development expense -Early discovery and other programs

Operating Segments [Member] | Personnel-Related General and Administrative Expenses [Member]

1,021

1,245

2,015

2,239

Other research and development expenses

$ 2,487

$ 2,252

$ 5,596

$ 4,663

[1]	Other segment items consist of interest income, interest expense, sublease income – related party, and change in fair value of simple agreement for future equity.

Retirement Plan

6 Months Ended

Jun. 30, 2026

Retirement Benefits [Abstract]

Retirement Plan

15. Retirement Plan

The Company has a U.S. tax-qualified employee savings and retirement 401(k) plan, covering all qualified employees. Participants may elect a salary deferral up to the statutorily prescribed annual limit for tax-deferred contributions. The Company may make matching contributions to each eligible participant’s account based on a percentage of the participant’s elective deferral

contribution. Matching contributions amounted to $0.3 million during each of the three months ended June 30, 2026 and 2025, respectively, and $0.8 million and $0.7 million for the six months ended June 30, 2026 and 2025, respectively.

The entire disclosure for retirement benefits.

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Related Party Transactions

Fair Value Measurements - Schedule of Financial Assets Measured at Fair Value on a Recurring Basis and Indicate the Level of the Fair Value Hierarchy (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Dec. 31, 2025	Jun. 30, 2025
Cash equivalents:
Cash and cash equivalents	$ 1,087,060	$ 27,711	$ 80,394
Fair Value, Recurring [Member]
Cash equivalents:
Cash and cash equivalents	1,119,383	27,133
Fair Value, Recurring [Member] \| Level 1
Cash equivalents:
Cash and cash equivalents	1,075,747	27,133
Fair Value, Recurring [Member] \| Level 2
Cash equivalents:
Cash and cash equivalents	43,636	0
Fair Value, Recurring [Member] \| Level 3
Cash equivalents:
Cash and cash equivalents	0	0
Money market funds \| Fair Value, Recurring [Member]
Cash equivalents:
Cash and cash equivalents	1,075,747	27,133
Money market funds \| Fair Value, Recurring [Member] \| Level 1
Cash equivalents:
Cash and cash equivalents	1,075,747	27,133
Money market funds \| Fair Value, Recurring [Member] \| Level 2
Cash equivalents:
Cash and cash equivalents	0	0
Money market funds \| Fair Value, Recurring [Member] \| Level 3
Cash equivalents:
Cash and cash equivalents	0	$ 0
U.S. Treasury bills \| Fair Value, Recurring [Member]
Cash equivalents:
Cash and cash equivalents	9,999
Marketable Securities	33,637
U.S. Treasury bills \| Fair Value, Recurring [Member] \| Level 1
Cash equivalents:
Cash and cash equivalents	0
Marketable Securities	0
U.S. Treasury bills \| Fair Value, Recurring [Member] \| Level 2
Cash equivalents:
Cash and cash equivalents	9,999
Marketable Securities	33,637
U.S. Treasury bills \| Fair Value, Recurring [Member] \| Level 3
Cash equivalents:
Cash and cash equivalents	0
Marketable Securities	$ 0

Segment Reporting (Additional Information) (Details)	6 Months Ended
Segment Reporting (Additional Information) (Details)	Jun. 30, 2026 Segment
Segment Reporting [Abstract]
Number of Reportable Segments	1
Number of Operating Segments	1
Description of Segment	The CODM manages the Company’s operations on a consolidated basis and uses consolidated net loss to assess financial performance and allocate resources. Consolidated net loss is used by the CODM to make key operating decisions, such as the determination of the rate at which the Company seeks to grow its research and development initiatives and the allocation of capital between research and development and general and administrative expenses.

Related Party Transactions

6 Months Ended

Jun. 30, 2026

13. Related Party Transactions

In December 2019, the Company entered into a non-cancelable sublease arrangement with a related party to sublease approximately 50% of the Company’s leased space at 30 Acorn Park Drive in Cambridge, Massachusetts through February 2025. In January 2024, the Company and the sublessee amended the sublease arrangement to extend the sublease date through December 2025. The sublessee is considered a related party due to common board members and stockholders. The related party was required to make lease payments and payments for its proportionate share of related occupancy costs to the Company. The sublease expired in December 2025.

The Company recorded sublease income of $1.1 million and $2.1 million for the three and six months ended June 30, 2025, respectively. In addition, the Company received payments from the related party of $0.5 million and $1.1 million during the three and six months ended June 30, 2025, respectively, representing the related party’s share of occupancy costs. Of the amounts received, $0.5 million and $1.0 million were recorded as a reduction of research and development expense for the three and six months ended June 30, 2025, respectively, and less than $0.1 million and $0.1 million was recorded as a reduction of general and administrative expense for the three and six months ended June 30, 2025, respectively, in the condensed consolidated statements of operations and comprehensive loss.

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

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Share-Based Payment Arrangement [Abstract]

Stock-Based Compensation

6 Months Ended

Jun. 30, 2026

Stock-Based Compensation

8. Stock-Based Compensation

2016 Employee, Director and Consultant Equity Incentive Plan

The Company’s 2016 Employee, Director and Consultant Equity Incentive Plan, as amended (the “2016 Plan”), provides for the Company to sell or award restricted common stock or to grant incentive and nonqualified stock options for the purchase of common stock (or other stock-based awards) to its founders, employees, officers, directors and consultants.

As of December 31, 2025, 10,826,224 shares of common stock were authorized and reserved for issuance under the 2016 Plan. The remaining shares reserved for issuance under the 2016 Plan ceased to be available for issuance at the time the January 2026 Plan was adopted. There will be no further awards granted under the 2016 Plan, but all outstanding awards under the 2016 Plan will continue to be governed by the 2016 Plan.

2026 Stock Option and Grant Plan

On January 6, 2026, the Board of Directors adopted and the Company’s stockholders approved the 2026 Stock Option and Grant Plan (the “January 2026 Plan”). The January 2026 Plan provides for the grant of incentive stock options, nonqualified stock options, restricted stock awards and other stock-based awards to the Company’s officers, employees, directors, consultants, and other key persons.

The number of shares of common stock authorized and reserved for issuance under the January 2026 Plan was initially 8,873,223 shares. The remaining shares reserved for issuance under the January 2026 Plan ceased to be available for issuance at the time the 2026 Plan became effective. There will be no further awards granted under the January 2026 Plan, but all outstanding awards under the January 2026 Plan will continue to be governed by the January 2026 Plan.

2026 Stock Option and Incentive Plan

In May 2026, the Board of Directors adopted, and in June 2026 the Company’s stockholders approved, the 2026 Stock Option and Incentive Plan (the “2026 Plan”), which became effective in June 2026. The 2026 Plan provides for the grant of incentive stock options, nonqualified stock options, restricted stock units and other stock-based awards to the Company’s officers, employees, directors and consultants.

The number of shares of common stock authorized and reserved for issuance under the 2026 Plan was initially 11,070,000 shares. The 2026 Plan provides that the number of shares reserved and available for issuance under the 2026 Plan will automatically increase on January 1, 2027 and each January 1 thereafter during the term of the 2026 Plan, by (i) 5% of the sum of (A) the number of shares of common stock issued and outstanding on the immediately preceding December 31, (B) the number of shares underlying the Company's outstanding preferred stock (determined on an as-converted basis) on the immediately preceding December 31, and (C) the number of shares of common stock issuable pursuant to the exercise of any outstanding pre-funded warrants on the immediately preceding December 31, or (ii) such lesser number of shares as determined by the compensation committee of the Board of Directors.

The shares of common stock underlying any awards under the 2026 Plan, the January 2026 Plan and 2016 Plan that are forfeited, cancelled, held back upon exercise or settlement of an award to satisfy the exercise price or tax withholding, reacquired by the Company prior to vesting, satisfied without the issuance of stock, expire, or are otherwise terminated (other than by exercise) will be added back to the shares of common stock available for issuance under the 2026 Plan. As of June 30, 2026, there were 10,895,110 shares available for future issuance under the 2026 Plan.

Upon stock option exercise, the Company delivers newly issued shares to the participant. Stock option vesting typically occurs over four years for employees and directors and is at the discretion of the Board of Directors. Stock options typically have a maximum term of ten years.

2026 Employee Stock Purchase Plan

In May 2026, the Board of Directors adopted, and in June 2026 the Company’s stockholders approved, the 2026 Employee Stock Purchase Plan (the “ESPP”), which became effective in June 2026. A total of 1,110,000 shares of common stock were initially reserved for issuance under the ESPP. The ESPP provides that the number of shares reserved and available for issuance will automatically increase on January 1, 2027 and each January 1 thereafter through January 1, 2036, by the least of (i) 1,110,000 shares of common stock, (ii) 1% of the sum of (A) the number of shares of common stock issued and outstanding on the immediately preceding December 31, (B) the number of shares underlying the Company’s outstanding preferred stock (determined on an as-converted basis) on the immediately preceding December 31, and (C) the number of shares of common stock issuable pursuant to the

exercise of any outstanding pre-funded warrants on the immediately preceding December 31, or (iii) such lesser number of shares of common stock as determined by the administrator of the ESPP. As of June 30, 2026, there were 1,110,000 shares available for future issuance under the ESPP.

Stock Option Valuation

The fair value of each stock option granted was estimated on the date of grant using the Black-Scholes option-pricing model and the assumptions summarized in the following table:


	Three Months Ended June 30,		Six Months Ended June 30,
	2026	2025	2026	2025
Expected volatility	89.70% - 90.12%	92.88%	89.70% - 90.15%	92.88% - 93.00%
Expected dividend yield	—	—	—	—
Expected term (in years)	5.50 - 6.25	6.25	5.50 - 6.25	6.25
Risk-free interest rate	3.98% - 4.29%	4.04%	3.70% - 4.29%	4.04%
Fair value of common stock	$4.09 - $20.00	$2.42	$3.14 - $20.00	$2.42

The following table presents a summary of all stock option activity:


	Shares			Weighted- Average Exercise Price per Share		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2025		9,098,233		$	2.64		7.72	$	3,386
Granted		7,435,819			3.82
Exercised		(421,313	)		1.83
Canceled or forfeited		(424,184	)		2.18
Outstanding at June 30, 2026		15,688,555		$	3.23		8.36	$	378,796
Vested and expected to vest at June 30, 2026		15,688,555		$	3.23		8.36	$	378,796
Vested and exercisable at June 30, 2026		5,935,504		$	2.93		7.12	$	145,130

The weighted-average grant date fair values of stock options granted during the six months ended June 30, 2026 and 2025 were $2.92 and $1.89 per share, respectively. The intrinsic values of stock options exercised were $2.5 million and less than $0.1 million during the six months ended June 30, 2026 and 2025, respectively.

Total unrecognized compensation expense related to unvested stock options was approximately $22.3 million as of June 30, 2026, which the Company expects to recognize over a weighted-average period of approximately 3.1 years.

Total unrecognized compensation expense related to unvested stock options with a market condition was approximately $0.2 million as of June 30, 2026, which the Company expects to recognize over a weighted-average period of approximately 0.7 years.

In May 2026, the Company entered into an advisory agreement with a former member of its Board of Directors following the individual’s resignation. Pursuant to the agreement, the Company granted the former board member an option to purchase 71,479 shares of common stock and provided for the continued vesting and exercisability of existing stock option awards. The Company concluded that the advisory services are not substantive for accounting purposes and recognized $1.1 million of stock-based compensation expense, representing the grant-date fair value of the new award, and $0.5 million related to the modification of the existing awards. The amounts are included in general and administrative expenses in the condensed consolidated statements of operations and comprehensive loss during the three and six months ended June 30, 2026.

Stock-Based Compensation Expense

The following table presents the classification of stock-based compensation expense included in the Company’s condensed consolidated statements of operations and comprehensive loss (in thousands):


	Three Months Ended June 30,				Six Months Ended June 30,
	2026		2025		2026		2025
Research and development	$	719	$	192	$	1,188	$	404
General and administrative		2,915		631		3,750		1,271
Total	$	3,634	$	823	$	4,938	$	1,675

Stockholders' Equity (Deficit) (Additional Information) (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	6 Months Ended
	Jun. 30, 2026	Jun. 30, 2026	Jun. 30, 2025	Dec. 31, 2025
Class of Stock [Line Items]
Common stock, shares authorized	600,000,000	600,000,000		81,000,000
Preferred stock, shares authorized	10,000,000	10,000,000		0
Preferred stock, par value	$ 0.0001	$ 0.0001		$ 0.0001
Common stock, shares outstanding	121,938,652	121,938,652		2,035,357
Common stock, par value	$ 0.0001	$ 0.0001		$ 0.0001
Share Price Per Share, Percentage		90.00%
Stock issuance cost		$ 680	$ 62
Net proceeds	$ 712,900
Converted shares		2,777,777
Common Stock [Member]
Class of Stock [Line Items]
Stock Issued During Period, Shares, New Issues	5,025,000
Number of share issued and sold	4,166,666
Common stock, shares authorized	600,000,000	600,000,000
Stock issuance cost	$ 57,600
Sale of stock price per share	$ 18	$ 18
Non Voting Shares [Member]
Class of Stock [Line Items]
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares outstanding	1,581,210	1,581,210
Undesignated Shares [Member]
Class of Stock [Line Items]
Preferred stock, shares authorized	10,000,000	10,000,000
Private Placement [Member]
Class of Stock [Line Items]
Sale of stock price per share	$ 18	$ 18
Net proceeds		$ 75,000
IPO [Member] \| Common Stock [Member]
Class of Stock [Line Items]
Stock Issued During Period, Shares, New Issues	38,525,000
Sale of stock price per share	$ 20	$ 20
Common Stock Warrants
Class of Stock [Line Items]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	24,152	24,152
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 4.82	$ 4.82
Stock Issued During Period, Shares, New Issues	20,468
Common Stock Warrants \| Private Placement [Member]
Class of Stock [Line Items]
Number of share issued and sold		4,166,666
Simple Agreement for Future Equity [Member] \| IPO [Member] \| Common Stock [Member]
Class of Stock [Line Items]
Share Price Per Share, Percentage		90.00%
Sale of stock price per share	$ 18	$ 18
Converted shares		2,777,777

Convertible Preferred Stock - Summary of Convertible Preferred Stock Except Share and Per Share Amounts (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2025	Jun. 30, 2026
Class of Stock [Line Items]
Shares of Preferred Stock Authorized	0	10,000,000
Shares of Preferred Stock Issued	0	0
Shares of Preferred Stock Outstanding	0	0
Series A Preferred Stock
Class of Stock [Line Items]
Shares of Preferred Stock Authorized	1,434,062
Original Issuance Price Per Share	$ 7.75
Shares of Preferred Stock Issued	1,434,062
Shares of Preferred Stock Outstanding	1,434,062
Carrying Value	$ 14,914
Liquidation Preference	$ 19,477
Shares of Common Stock Issuable Upon Conversion	1,002,805
Series B Preferred Stock
Class of Stock [Line Items]
Shares of Preferred Stock Authorized	4,658,112
Original Issuance Price Per Share	$ 14.06
Shares of Preferred Stock Issued	4,658,112
Shares of Preferred Stock Outstanding	4,658,112
Carrying Value	$ 65,388
Liquidation Preference	$ 106,351
Shares of Common Stock Issuable Upon Conversion	4,069,102
Series C Preferred Stock
Class of Stock [Line Items]
Shares of Preferred Stock Authorized	7,384,710
Original Issuance Price Per Share	$ 14.49
Shares of Preferred Stock Issued	7,384,710
Shares of Preferred Stock Outstanding	7,384,710
Carrying Value	$ 106,674
Liquidation Preference	$ 152,175
Shares of Common Stock Issuable Upon Conversion	6,540,022
Series D Preferred Stock
Class of Stock [Line Items]
Shares of Preferred Stock Authorized	16,537,979
Original Issuance Price Per Share	$ 10.76
Shares of Preferred Stock Issued	16,537,979
Shares of Preferred Stock Outstanding	16,537,979
Carrying Value	$ 177,581
Liquidation Preference	$ 225,956
Shares of Common Stock Issuable Upon Conversion	12,669,755
Series E Preferred Stock
Class of Stock [Line Items]
Shares of Preferred Stock Authorized	23,281,563
Original Issuance Price Per Share	$ 6.23
Shares of Preferred Stock Issued	23,281,563
Shares of Preferred Stock Outstanding	23,281,563
Carrying Value	$ 145,414
Liquidation Preference	$ 155,013
Shares of Common Stock Issuable Upon Conversion	15,128,745
Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Shares of Preferred Stock Authorized	53,296,426	0
Shares of Preferred Stock Issued	53,296,426	0
Shares of Preferred Stock Outstanding	53,296,426	0
Carrying Value	$ 509,971
Liquidation Preference	$ 658,972	$ 0
Shares of Common Stock Issuable Upon Conversion	39,410,429

Property and Equipment, Net

6 Months Ended

Jun. 30, 2026

Property, Plant, and Equipment [Abstract]

Property and Equipment, Net

4. Property and Equipment, Net

Property and equipment, net consisted of the following (in thousands):


	June 30,			December 31,
	2026			2025
Laboratory equipment	$	14,348		$	13,830
Leasehold improvements		4,692			4,563
Computer equipment		609			307
Furniture and fixtures		745			697
Assets not yet in service		289			131
Property and equipment		20,683			19,528
Less: accumulated depreciation and amortization		(13,965	)		(12,813	)
Property and equipment, net	$	6,718		$	6,715

Included in laboratory equipment are finance lease right-of-use assets with a cost basis of $2.9 million as of June 30, 2026 and December 31, 2025, and accumulated amortization expense of $0.9 million and $0.7 million as of June 30, 2026 and December 31, 2025, respectively.

During each of the three months ended June 30, 2026 and 2025, depreciation and amortization expense amounted to $0.6 million, which includes $0.2 million of finance lease right-of-use asset amortization in each period. During the six months ended June 30, 2026 and 2025, depreciation and amortization expense amounted to $1.2 million and $1.3 million, respectively, which includes $0.3 million of finance lease right-of-use asset amortization in each period.

The entire disclosure for property, plant, and equipment. Includes, but is not limited to, land and land improvement; building; machinery and equipment; furniture and fixture; and work of art, historical treasure, or similar asset classified as collection.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Convertible Preferred Stock - Summary of the significant Level 3 Unobservable Inputs (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Class of Stock [Line Items]
Expected volatility		92.88%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Expected term (in years)		6 years 3 months		6 years 3 months
Risk-free interest rate		4.04%		4.04%
Maximum [Member]
Class of Stock [Line Items]
Expected volatility	90.12%		90.15%	93.00%
Expected term (in years)	6 years 3 months		6 years 3 months
Risk-free interest rate	4.29%		4.29%
Minimum [Member]
Class of Stock [Line Items]
Expected volatility	89.70%		89.70%	92.88%
Expected term (in years)	5 years 6 months		5 years 6 months
Risk-free interest rate	3.98%		3.70%
Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Expected volatility			78.00%
Expected dividend yield			0.00%
Risk-free interest rate			3.60%
Convertible Preferred Stock [Member] \| Maximum [Member]
Class of Stock [Line Items]
Expected term (in years)			10 months 6 days
Convertible Preferred Stock [Member] \| Minimum [Member]
Class of Stock [Line Items]
Expected term (in years)			2 years 6 months

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Collaboration Agreements (Additional Information) (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		3 Months Ended		6 Months Ended
	Jun. 30, 2026	May 31, 2024	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025	Dec. 31, 2025
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Research and development cost			$ 39,377	$ 30,126	$ 77,130	$ 64,031
Accrued expenses and other current liabilities	$ 4,226		4,226		4,226		$ 726
Commercial milestone payments					$ 1,150,000
Proceeds From Issuance of Common Stock	712,900
Share price percentage					90.00%
Current liability	$ 62,839		$ 62,839		$ 62,839		56,791
Private Placement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Sale of stock price per share	$ 18		$ 18		$ 18
Proceeds From Issuance of Common Stock					$ 75,000
Research Collaboration Agreement with ARTBIO, Inc.
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Research and development cost		$ 10,000	$ 0	800	0	2,400
Increase (Decrease) in Operating Liabilities			0	500	0	1,400
Reduction of research and development expenses				$ 300		$ 1,000
Accrued expenses and other current liabilities	$ 2,700		$ 2,700		2,700		$ 2,700
Research Collaboration Agreement with ARTBIO, Inc. \| ARTBIO, Inc.
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Research and development cost		$ 10,000
License and Collaboration Agreement with Regeneron
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront payment	$ 50,000				50,000
Development milestone payments					$ 470,000
Stock Issued During Period, Shares, New Issues					4,166,666
Sale of stock price per share	$ 18		$ 18		$ 18
Proceeds From Issuance of Common Stock	$ 75,000				$ 75,000
Share price percentage					90.00%
Transaction price of performance obligations	41,700		$ 41,700		$ 41,700
Reduction Of The Transaction Price	8,300		8,300		8,300
Commitment at fair value	83,300		83,300		83,300
Contract With Customer Performance Obligation Unsatisfied Or Partially Unsatisfied	41,500		41,500		41,500
Company recognized revenue			100		100
Deferred revenue	41,500		41,500		41,500
Current liability	$ 10,400		$ 10,400		10,400
License and Collaboration Agreement with Regeneron \| Private Placement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Regulatory milestone payments					$ 575,000

Summary of Significant Accounting Policies (Tables)

6 Months Ended

Jun. 30, 2026

Schedule of Cash and Cash Equivalents

A reconciliation of the cash, cash equivalents, and restricted cash reported within the condensed consolidated balance sheets that sum to the total of the same amounts shown in the condensed consolidated statements of cash flows is as follows (in thousands):


	June 30,
	2026		2025
Cash and cash equivalents	$	1,087,060	$	80,394
Restricted cash – long-term		2,855		2,855
Total cash, cash equivalents and restricted cash	$	1,089,915	$	83,249

Term Loan - Schedule of Term Loan Balances (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Dec. 31, 2025
Short-Term Debt [Line Items]
Total term loan principal	$ 5,000	$ 12,500
Final payments	726	647
Unamortized debt discount and issuance costs	(16)	(70)
Debt, Current, Total	$ 5,710	$ 13,077

Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

Nature of the Business and Basis of Presentation

6 Months Ended

Jun. 30, 2026

Nature of the Business and Basis of Presentation

1. Nature of the Business and Basis of Presentation

Nature of Business

Parabilis Medicines, Inc. (the “Company”) is a clinical-stage biopharmaceutical company developing medicines addressing some of the most consequential, yet historically undruggable, protein targets driving human disease. The Company leverages its platform to pioneer a therapeutic modality, Helicons, which are stabilized helical peptides engineered to bind and precisely modulate proteins. The Company was incorporated in Delaware on July 10, 2015. The Company is developing preclinical and clinical drug candidates, primarily operates in the United States of America, and, to date, has devoted substantially all its efforts to research and development and fundraising activities.

Risk and Uncertainties

The Company is subject to risks and uncertainties common to clinical-stage companies in the biotechnology industry, including, but not limited to, development by competitors of new technological innovations, dependence on key personnel, protection of proprietary technology, compliance with government regulations, and ability to secure additional capital to fund operations. Product candidates resulting from the Company’s current discovery efforts will require significant additional research and development efforts, including extensive preclinical and clinical testing and regulatory approval prior to commercialization. These efforts will require significant amounts of additional capital, adequate personnel, infrastructure, and extensive compliance reporting capabilities. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from product sales.

Reverse Stock Split

On June 3, 2026, the Company effected a 1-for-1.5389 reverse stock split of its issued and outstanding shares of common stock and a proportional adjustment to the existing conversion ratios of each series of the Company's convertible preferred stock and the IPO Discount Price (see Note 10, Simple Agreement for Future Equity) of the Company's simple agreement for future equity (“SAFE”). Accordingly, all share and per share amounts for all periods presented in the accompanying condensed consolidated financial statements and notes thereto have been adjusted retroactively, where applicable, to reflect this reverse stock split and adjustments of the convertible preferred stock conversion ratios and the IPO Discount Price for the SAFE.

Liquidity

The Company’s condensed consolidated financial statements have been prepared on the basis of continuity of operations, the realization of assets and satisfaction of liabilities in the ordinary course of business. In June 2026, the Company closed its initial public offering (“IPO”) pursuant to which it issued and sold 38,525,000 shares of common stock, inclusive of 5,025,000 shares of common stock sold pursuant to the underwriters' full exercise of their option to purchase additional common stock, at a public offering price of $20.00 per share. In addition, the Company issued and sold 4,166,666 shares of common stock to Regeneron Pharmaceuticals, Inc. (“Regeneron”) in a concurrent private placement at a price per share of $18.00, or 90% of the public offering price. The aggregate net proceeds received by the Company from the IPO and concurrent private placement were $787.9 million, after deducting underwriting discounts and commissions and offering expenses of $57.6 million. Additionally, in June 2026, the Company received a non-refundable upfront payment in the amount of $50.0 million under its License and Collaboration Agreement (the “Regeneron Agreement”) with Regeneron. Prior to the IPO, the Company received aggregate gross proceeds of $811.8 million from sales of convertible preferred stock, $15.0 million from borrowings under a term loan, and $50.0 million of gross proceeds from the issuance of a SAFE. The Company has incurred net losses and negative operating cash flows since inception and has an accumulated deficit of $639.3 million at June 30, 2026. The Company expects that its cash, cash equivalents and marketable securities will be sufficient to fund its operations for at least twelve months from the date these condensed consolidated financial statements were issued.

The Company will need additional financing to support its continuing operations and pursue its growth strategy. Until such time as the Company can generate significant revenue from product sales, if ever, the Company expects to finance its cash needs through a combination of equity offerings, debt or royalty financings, and collaborations. The Company may not be able to obtain financing on acceptable terms, or at all, and the Company may not be able to enter into collaborations or other arrangements. The terms of any financing may adversely affect the holdings or the rights of the Company’s stockholders. If the Company is unable to raise additional funds through these sources or other sources of funding when needed, the Company could be forced to delay, reduce or eliminate its research and development programs, product portfolio expansion or commercialization efforts, which could adversely affect its business prospects. Although management continues to pursue these plans, there is no assurance that the Company will be successful in obtaining sufficient funding on terms acceptable to the Company to fund continuing operations, if at all.

Basis of Presentation

The accompanying unaudited condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries, Parabilis Security Corporation and Parabilis Medicines (Shanghai) Ltd. Co. All intercompany accounts and transactions have been eliminated in consolidation.

The Company’s unaudited condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”) for interim reporting and as required by Regulation S-X, Rule 10-01. Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates (“ASU”) of the Financial Accounting Standards Board (“FASB”).

The condensed consolidated interim financial statements have been prepared on the same basis as the audited annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for a fair statement of the Company’s financial position as of June 30, 2026, and the results of its operations for the three and six months ended June 30, 2026 and 2025, and cash flows for the six months ended June 30, 2026 and 2025. The condensed balance sheet as of December 31, 2025 was derived from audited annual financial statements but does not include all disclosures required by GAAP. The results of operations for the interim periods are not necessarily indicative of results to be expected for the year ending December 31, 2026, any other interim periods, or any future year or period.

Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025
Cash flows from operating activities
Net loss	$ (97,779)	$ (73,136)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,199	1,272
Accretion of discounts on marketable securities	(208)	473
Stock-based compensation expense	4,938	1,675
Non-cash interest expense	133	165
Non-cash lease expense	3,353	3,066
Change in fair value of simple agreement for future equity	5,556	0
Changes in operating assets and liabilities:
Rent receivable - related party	0	120
Due from related party	0	51
Prepaid expenses and other assets	(5,364)	66
Operating lease liabilities	(3,510)	(3,081)
Deferred revenue	41,519	0
Accounts payable, accrued expenses and other liabilities	(2,659)	4,085
Net cash used in operating activities	(52,822)	(65,244)
Cash flows from investing activities
Purchases of marketable securities	(33,447)	(16,664)
Proceeds from maturities of marketable securities	0	47,954
Purchases of property and equipment	(985)	(90)
Net cash (used in) provided by investing activities	(34,432)	31,200
Cash flows from financing activities
Payments of convertible preferred stock issuance costs	(680)	(62)
Proceeds from issuance of simple agreement for future equity	50,000	0
Proceeds from initial public offering, net of underwriting discounts and commissions	718,240	0
Payments of initial public offering costs	(2,499)	0
Proceeds from concurrent private placement of common stock	83,333	0
Principal payments on finance leases	(311)	(284)
Principal payments on debt	(7,500)	0
Proceeds from exercise of stock options	771	9
Net cash provided by financing activities	1,146,603	67,154
Increase in cash, cash equivalents and restricted cash	1,059,349	33,110
Cash, cash equivalents and restricted cash at beginning of period	30,566	50,139
Cash, cash equivalents and restricted cash at end of period	1,089,915	83,249
Supplemental disclosure of cash flow information:
Cash paid for interest	414	632
Supplemental disclosure of non-cash investing and financing activities:
Purchases of property and equipment included in accounts payable	277	30
Initial public offering costs included in accounts payable and accrued expenses	2,853	0
Conversion of convertible preferred stock into common stock and non-voting common stock	814,540	0
Conversion of Stock, Amount Issued	55,600
Conversion of simple agreement for future equity into common stock	55,556	0
Settlement of Series E preferred stock tranche right liability	0	2,167
Series E Convertible Preferred Stock [Member]
Cash flows from financing activities
Proceeds from issuance of convertible preferred stock	0	67,491
Series F Convertible Preferred Stock [Member]
Cash flows from financing activities
Proceeds from issuance of convertible preferred stock	$ 305,249	$ 0

Stock-Based Compensation - Schedule of stock option granted using the Black-Scholes option-pricing mode and assumptions (Details) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Expected volatility		92.88%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Expected term (in years)		6 years 3 months		6 years 3 months
Risk-free interest rate		4.04%		4.04%
Fair value of common stock		$ 2.42		$ 2.42
Maximum [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Expected volatility	90.12%		90.15%	93.00%
Expected term (in years)	6 years 3 months		6 years 3 months
Risk-free interest rate	4.29%		4.29%
Fair value of common stock	$ 20		$ 20
Minimum [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Expected volatility	89.70%		89.70%	92.88%
Expected term (in years)	5 years 6 months		5 years 6 months
Risk-free interest rate	3.98%		3.70%
Fair value of common stock	$ 4.09		$ 3.14

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Schedule of Term Loan Balances

Term Loan (Tables)

6 Months Ended

Jun. 30, 2026

Debt Disclosure [Abstract]

Term loan balances, including final payments, are summarized as follows (in thousands):


	June 30,			December 31,
	2026			2025
Total term loan principal	$	5,000		$	12,500
Final payments		726			647
Unamortized debt discount and issuance costs		(16	)		(70	)
Term loan, net of discount	$	5,710		$	13,077

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

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Stock-Based Compensation - Schedule of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-Based Compensation Expense	$ 3,634	$ 823	$ 4,938	$ 1,675
Location, Statement of Income, Balance [Axis]: us-gaap:GeneralAndAdministrativeExpense
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-Based Compensation Expense	2,915	631	3,750	1,271
Location, Statement of Income, Balance [Axis]: us-gaap:ResearchAndDevelopmentExpense
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-Based Compensation Expense	$ 719	$ 192	$ 1,188	$ 404

Summary of Significant Accounting Policies (Policies)

6 Months Ended

Jun. 30, 2026

Cash and Cash Equivalents

Use of Estimates

The preparation of the Company’s condensed consolidated financial statements in conformity with GAAP requires management to make estimates, judgments and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of expenses during the reporting periods. Significant estimates reflected within these condensed consolidated financial statements include the estimated fair value of the Company’s common stock utilized in the determination of stock-based compensation expense prior to the IPO, the determination of the incremental borrowing rate for leases, the estimated fair value of the convertible preferred stock and SAFE, revenue recognition, as well as accrued research and development expenses. On an ongoing basis, management evaluates its estimates as there are changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. Actual results may differ from those estimates or assumptions.

The Company considers all highly liquid investments with an original maturity of three months or less at the date of purchase to be cash equivalents. The Company’s cash equivalents consist of funds deposited in money market mutual funds and U.S. Treasury bills and are recorded at fair value.


	June 30,
	2026		2025
Cash and cash equivalents	$	1,087,060	$	80,394
Restricted cash – long-term		2,855		2,855
Total cash, cash equivalents and restricted cash	$	1,089,915	$	83,249

Restricted Cash

As of June 30, 2026 and December 31, 2025, restricted cash consists of $2.9 million serving as collateral for a letter of credit required under the Company’s facility lease arrangement.

Concentration of Risk

Financial instruments that potentially subject the Company to credit risk consist of cash and cash equivalents, and marketable securities. The Company’s cash deposits generally do not exceed Federal Deposit Insurance Corporation (“FDIC”) limits. The Company’s cash equivalents consist of money market funds that are not insured by the FDIC; however, the Company has not experienced any losses in such accounts and believes that such funds are not exposed to any significant credit or concentration risk beyond the risks associated with commercial banking relationships. The Company maintains each of its cash and cash equivalents balances with financial institutions that management believes are creditworthy. The Company’s investment policy includes guidelines on the quality of the financial institutions and financial instruments and defines allowable investments that the Company believes minimize exposure to concentration of credit risk. The Company’s marketable securities consist of U.S. Treasury bills. The Company believes these investments present minimal credit risk.

The Company relies, and expects to continue to rely, on a small number of vendors and contract research organizations to manufacture certain supplies and raw materials for its research and development programs and to conduct clinical trials. These programs could be adversely affected by a significant interruption in these manufacturing services or the availability of raw materials, or an interruption in the provision of services provided by the Company’s contract research organizations.

Stock-Based Compensation

The Company measures all stock options and other stock-based awards granted to employees, directors and non-employees based on the award’s fair value on the date of the grant and recognizes compensation expense related to those awards over the requisite service period, which is generally the vesting period of the respective award. The Company primarily issues stock options with only service-based vesting conditions and records the expense for these awards using the straight-line method. To a lesser extent, the Company has also granted awards with either service and performance-based vesting conditions or market and performance-based vesting conditions, and records expense based on the grant-date fair value over the requisite service period using the accelerated attribution method if the achievement of the performance condition is considered probable. At each reporting date, the Company estimates the probability that specified performance criteria will be achieved and does not begin to recognize compensation expense until it is probable that the performance-based vesting condition will be achieved.

The Company classifies stock-based compensation expense in its condensed consolidated statements of operations and comprehensive loss in the same manner in which the award recipient’s payroll costs or service payments are classified.

The fair values of stock options with only service-based or performance-based conditions are estimated using the Black-Scholes option-pricing model. Prior to the IPO, the Company’s board of directors (the “Board of Directors”) determined the fair value of the Company’s common stock, with input from management, considering the Company’s most recently available third-party valuations of common stock, as well as additional factors which may have changed since the date of the most recent valuation through the date of grant. Subsequent to the completion of the IPO, the fair value of the Company’s common stock underlying its stock options is based on the quoted market price of the Company’s common stock on the grant date. The expected volatility of the Company’s stock options is based upon the historical volatility of a set of publicly-traded peer companies, as there is limited stock price data available for the Company’s common stock since the IPO. The Company will continue to apply this process until sufficient historical information regarding the volatility of its own stock price becomes available. The expected term of the Company’s stock options granted has been determined utilizing the “simplified” method for awards that qualify as “plain-vanilla” options, which is presumed to be the midpoint between the vesting date and the end of the contractual term. If vesting is subject to a performance condition, the expected term is based on the mid-point between the explicit service period and the contractual term of the option. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. The expected dividend yield is zero, because the Company has never paid cash dividends on common stock and does not expect to pay any such dividends in the foreseeable future. The Company accounts for forfeitures of share-based compensation awards as they occur.

Revenue Recognition

The Company enters into license and collaboration agreements which are within the scope of ASC Topic 606, Revenue from Contracts with Customers (“ASC 606”), under which the Company licenses rights to its technology and certain of the Company’s drug candidates and performs research and development services for third parties. The terms of these arrangements typically include payment of one or more of the following: non-refundable, up-front fees; reimbursement of research and development costs; development, regulatory and commercial milestone payments; and royalties on net sales of licensed products.

Under ASC 606, an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which the entity expects to receive in exchange for those goods or services. To determine the

appropriate amount of revenue to be recognized for arrangements determined to be within the scope of ASC 606, the Company performs the following five steps: (i) identification of contract(s) with a customer; (ii) identification of the performance obligations; (iii) measurement of the transaction price, including the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations; and (v) recognition of revenue when (or as) the Company satisfies each performance obligation. The Company only applies the five-step model to contracts when it is probable that the Company will collect consideration to which it is entitled in exchange for the goods or services it transfers to the customer.

The promised goods or services in the Company’s arrangements typically consist of license rights to the Company’s intellectual property and research and development services. The Company also has optional additional items in contracts, which are considered marketing offers and are accounted for as separate contracts with the customer if such option is elected by the customer, unless the option provides a material right which would not be provided without entering into the contract. Performance obligations are promised goods or services in a contract to transfer a distinct good or service to the customer. Promised goods or services are considered distinct when (i) the customer can benefit from the good or service on its own or together with other readily available resources and (ii) the promised good or service is separately identifiable from other promises in the contract. In assessing whether promised goods or services are distinct, the Company considers factors such as the stage of development of the underlying intellectual property, the capabilities of the customer to develop the intellectual property on their own and the availability of the required expertise.

The Company estimates the transaction price based on the amount expected to be received for transferring the promised goods or services in the contract. The consideration may include both fixed consideration and variable consideration. At the inception of each arrangement that includes variable consideration and at each reporting period, the Company evaluates the amount of potential payment and the likelihood that the payments will be received. The Company utilizes either the most likely amount method or expected value method to estimate the amount expected to be received based on which method better predicts the amount of consideration to which the Company will be entitled. If it is probable that a significant revenue reversal would not occur, the variable consideration is included in the transaction price.

The Company’s contracts often include development, regulatory and commercial milestone payments. At contract inception and at each reporting period, the Company evaluates whether the milestones are considered probable of being reached and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the Company’s control or the licensee’s control, such as regulatory approvals, are not included in the transaction price. At the end of each subsequent reporting period, the Company re-evaluates the probability of achievement of such development milestones and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect license, collaboration and other revenues and earnings in the period of adjustment.

For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, the Company has not recognized any royalty revenue resulting from its license and collaboration arrangement.

The Company allocates the transaction price based on the estimated standalone selling price of the underlying performance obligations or in the case of certain variable consideration to one or more performance obligations. The Company must develop assumptions that require judgment to determine the standalone selling price for each performance obligation identified in the contract. The Company utilizes key assumptions to determine the standalone selling price, which may include other comparable transactions, pricing considered in negotiating the transaction and the estimated costs to complete the respective performance obligation. Certain variable consideration is allocated specifically to one or more performance obligations in a contract when the terms of the variable consideration relate to the satisfaction of the performance obligation and the resulting amounts allocated to each performance obligation are consistent with the amounts the Company would expect to receive for each performance obligation.

For performance obligations consisting of licenses and other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, up-front fees. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. If the license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company will recognize revenue from non-refundable, up-front fees allocated to the license when the license is transferred to the customer and the customer is able to use and benefit from the license.

The Company receives payments from its customers based on billing schedules established in each contract. Up-front payments and fees are recorded as a contract liability (deferred revenue) upon receipt or when due until the Company performs its obligations under these arrangements. Amounts are recorded as accounts receivable when the right to consideration is unconditional and only the passage of time is required before payment is due. If the right to consideration is subject to a condition other than the passage of time, then the amount is recorded as a contract asset until the right to payment becomes unconditional. In accordance with ASC 606, the Company presents contract assets and contract liabilities on a net basis by customer contract.

Deferred Offering Costs

The Company capitalizes certain legal, professional, accounting and other third-party fees that are directly associated with in-process equity financings as deferred offering costs until such financings are consummated. After consummation of the equity financing, these costs are recorded as a reduction of the proceeds from the offering, either as a reduction of the carrying value of the convertible preferred stock or in stockholders’ equity (deficit) as a reduction of additional paid-in capital. Should the planned equity financing be abandoned, the deferred offering costs are expensed immediately as a charge to operating expenses in the condensed consolidated statements of operations and comprehensive loss. At the closing of the IPO, a total of $5.4 million of deferred offering costs were reclassified to additional paid-in capital within stockholders’ equity (deficit). As such, no deferred offering costs were capitalized as of June 30, 2026. As of December 31, 2025, the Company had $0.6 million of deferred offering costs included in other assets on the condensed consolidated balance sheets.

Net Loss Per Share

Basic net loss per common share is calculated by dividing net loss adjusted for cumulative dividends on convertible preferred stock accrued during the period, whether or not declared, and the value of any deemed dividends resulting from down-round adjustments to convertible preferred stock, where applicable, by the weighted-average number of shares of common stock outstanding during the period, without consideration of potentially dilutive securities. Diluted net loss per share is computed by dividing the net loss allocable to common stockholders by the weighted-average number of shares of common stock and potentially dilutive securities outstanding for the period. For purposes of the diluted net loss per share calculation, the convertible preferred stock, common stock warrants, preferred stock tranche rights, stock options, and SAFE are considered potentially dilutive securities.

Basic and diluted net loss allocable to common stockholders per share is presented in conformity with the two-class method required for participating securities as all series of convertible preferred stock and SAFE are considered participating securities. The Company’s participating securities do not have a contractual obligation to share in the Company’s losses. As such, the net loss was attributed entirely to common stockholders.

Following the closing of the IPO, the Company has two series of common stock outstanding comprised of voting common stock and non-voting common stock. The rights of the holders of voting common stock and non-voting common stock are identical, except with respect to voting and conversion. Each share of non-voting common stock may be converted into one share of voting common stock at any time at the option of the holder, subject to certain beneficial ownership limitations. Net loss per share for each series of common stock issued is the same as they are entitled to the same liquidation and dividend rights.

Segment Information

Operating segments are defined as components of an enterprise for which separate and discrete information is available for evaluation by the chief operating decision-maker (“CODM”), in deciding how to allocate resources and assess performance. The Company's CODM, its chief executive officer, manages the Company’s operations on a consolidated basis for the purpose of allocating resources. All of the Company’s long-lived assets are held in the United States. Refer to Note 16, Segment Reporting, for further disclosure regarding the Company’s segment information.

Recently Issued Accounting Pronouncements Not Yet Adopted

From time to time, new accounting pronouncements are issued by the FASB or other standard setting bodies and adopted by the Company as of the specified effective date. The Company qualifies as an “emerging growth company” as defined in the Jumpstart Our Business Startups Act of 2012 and has elected not to “opt out” of the extended transition related to complying with new or revised accounting standards, which means that when a standard is issued or revised and it has different application dates for public and non-public companies, the Company can adopt the new or revised standard at the time non-public companies adopt the new or revised standard and can do so until such time that the Company either (i) irrevocably elects to “opt out” of such extended transition period or (ii) no longer qualifies as an emerging growth company. The Company may choose to adopt any new or revised accounting standards early whenever such early adoption is permitted for non-public companies.

In November 2024, the FASB issued ASU No. 2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses (“ASU 2024-03”). ASU 2024-03 requires disclosure of disaggregated information about certain income statement expense line items on an annual and interim basis, including purchases of inventory, employee compensation, depreciation, intangible asset amortization and depletion for each income statement line item that contains those expenses. ASU 2024-03 also requires certain amounts already disclosed under existing GAAP to also be disclosed as a separate category in disaggregated expense tables, if those amounts are recognized in the relevant expense line item. The amendments in ASU 2024-03 will be effective for the Company in annual reporting periods beginning after December 15, 2026, and interim reporting periods within annual reporting periods beginning after December 15, 2027, with early adoption permitted. The standard may be applied prospectively or retrospectively. The Company is currently evaluating the impact of adopting ASU 2024-03.

Recently Adopted Accounting Pronouncements

In May 2025, the FASB issued ASU No. 2025-04, Compensation—Stock Compensation (Topic 718) and Revenue from Contracts with Customers (Topic 606): Clarifications to Share-Based Consideration Payable to a Customer (“ASU 2025-04”), which requires that a grantor apply the guidance in ASC Topic 718, Compensation—Stock Compensation (“ASC 718”) to measure and classify share-based consideration payable to a customer. The amended guidance also requires a reporting entity to assess if share-based consideration payable to a customer contains vesting conditions, including whether or not those vesting conditions represent service conditions or performance conditions. During the three months ended June 30, 2026, the Company early adopted this standard on a modified retrospective basis effective January 1, 2026. The adoption of ASU 2025-04 did not have a material impact on the condensed consolidated financial statements.

Accrued Expenses and Other Current Liabilities (Tables)

6 Months Ended

Jun. 30, 2026

Other Liabilities Disclosure [Abstract]

Schedule of Accrued Expenses and Other Current Liabilities

The following table summarizes accrued expenses and other current liabilities (in thousands):


	June 30,		December 31,
	2026		2025
Accrued employee compensation and benefits	$	5,459	$	9,079
Accrued research and development expenses		8,888		8,334
Accrued offering costs		1,399		491
Other		4,226		726
Total	$	19,972	$	18,630

Condensed Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (unaudited) - USD ($) $ in Thousands	Total	Common Stock [Member]	Non-Voting Common Stock [Member]	Convertible Preferred Stock [Member]	Additional Paid-in Capital [Member]	AOCI Attributable to Parent [Member]	Retained Earnings [Member]	Series E Preferred Stock [Member] Convertible Preferred Stock [Member]	Series F Preferred Stock [Member] Convertible Preferred Stock [Member]
Beginning Balance Shares at Dec. 31, 2024		2,017,588	0	42,459,887
Beginning Balance Value at Dec. 31, 2024	$ (383,936)	$ 0	$ 0	$ 440,375	$ 11,658	$ 21	$ (395,615)
Stock based compensation expense	852				852
Change in unrealized gains (losses) on marketable securities	(16)					(16)
Stock Issued During Period, Shares, New Issues								10,836,539
Stock Issued During Period, Value, New Issues								$ 69,596
Net loss	(38,326)						(38,326)
Ending Balance Shares at Mar. 31, 2025		2,017,588	0	53,296,426
Ending Balance Value at Mar. 31, 2025	(421,426)	$ 0	$ 0	$ 509,971	12,510	5	(433,941)
Beginning Balance Shares at Dec. 31, 2024		2,017,588	0	42,459,887
Beginning Balance Value at Dec. 31, 2024	(383,936)	$ 0	$ 0	$ 440,375	11,658	21	(395,615)
Net loss	(73,136)
Ending Balance Shares at Jun. 30, 2025		2,023,379	0	53,296,426
Ending Balance Value at Jun. 30, 2025	(455,409)	$ 0	$ 0	$ 509,971	13,342	0	(468,751)
Beginning Balance Shares at Mar. 31, 2025		2,017,588	0	53,296,426
Beginning Balance Value at Mar. 31, 2025	(421,426)	$ 0	$ 0	$ 509,971	12,510	5	(433,941)
Issuance of common stock upon exercise of stock options shares		5,791
Issuance of common stock upon exercise of stock options	9				9
Stock based compensation expense	823				823
Change in unrealized gains (losses) on marketable securities	(5)					(5)
Net loss	(34,810)						(34,810)
Ending Balance Shares at Jun. 30, 2025		2,023,379	0	53,296,426
Ending Balance Value at Jun. 30, 2025	(455,409)	$ 0	$ 0	$ 509,971	13,342	0	(468,751)
Beginning Balance Shares at Dec. 31, 2025		2,035,357	0	53,296,426
Beginning Balance Value at Dec. 31, 2025	(526,495)	$ 0	$ 0	$ 509,971	15,009	0	(541,504)
Issuance of common stock upon exercise of stock options shares		92,699
Issuance of common stock upon exercise of stock options	187				187
Stock based compensation expense	1,304				1,304
Stock Issued During Period, Shares, New Issues									49,518,175
Stock Issued During Period, Value, New Issues									$ 304,569
Net loss	(45,316)						(45,316)
Ending Balance Shares at Mar. 31, 2026		2,128,056		102,814,601
Ending Balance Value at Mar. 31, 2026	(570,320)			$ 814,540	16,500		(586,820)
Beginning Balance Shares at Dec. 31, 2025		2,035,357	0	53,296,426
Beginning Balance Value at Dec. 31, 2025	$ (526,495)	$ 0	$ 0	$ 509,971	15,009	0	(541,504)
Issuance of common stock upon exercise of stock options shares	421,313
Net loss	$ (97,779)
Ending Balance Shares at Jun. 30, 2026		121,938,652	1,581,210,000
Ending Balance Value at Jun. 30, 2026	1,047,734	$ 12			1,687,023	(18)	(639,283)
Beginning Balance Shares at Mar. 31, 2026		2,128,056		102,814,601
Beginning Balance Value at Mar. 31, 2026	(570,320)			$ 814,540	16,500		(586,820)
Issuance of common stock upon exercise of stock options shares		328,614
Issuance of common stock upon exercise of stock options	584				584
Stock based compensation expense	3,634				3,634
Change in unrealized gains (losses) on marketable securities	(18)					(18)
Issuance of common stock in initial public offering		38,525,000
Issuance of common stock in initial public offering, Value	712,888	$ 4			712,884
Conversion of convertible preferred stock into common stock and non-voting common stock		73,992,071		(102,814,601)
Conversion of convertible preferred stock into common stock and non-voting common stock	814,540	$ 8	$ 1,581,210	$ (814,540)	814,532
Issuance of common stock in concurrent private placement,Shares		4,166,666
Issuance of common stock in concurrent private placement	83,333				83,333
Conversion of simple agreement for future equity into common stock, shares		2,777,777
Conversion of simple agreement for future equity into common stock, value	55,556				55,556
Net exercise of warrants to purchase common stock shares		20,468
Net loss	(52,463)						(52,463)
Ending Balance Shares at Jun. 30, 2026		121,938,652	1,581,210,000
Ending Balance Value at Jun. 30, 2026	$ 1,047,734	$ 12			$ 1,687,023	$ (18)	$ (639,283)

Condensed Consolidated Balance Sheets (unaudited) (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2026	Dec. 31, 2025
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	0
Preferred stock, shares outstanding	0	0
Preferred stock, shares issued	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	600,000,000	81,000,000
Common stock, shares outstanding	121,938,652	2,035,357
Common stock, shares issued	121,938,652	2,035,357
Convertible Preferred Stock [Member]
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	0	53,296,426
Preferred stock, shares outstanding	0	53,296,426
Preferred stock, shares issued	0	53,296,426
Preferred stock, liquidation preference value	$ 0	$ 658,972
Nonvoting Common Stock [Member]
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	200,000,000	0
Common stock, shares outstanding	1,581,210	0
Common stock, shares issued	1,581,210	0

Stock-Based Compensation - Schedule of stock option activity (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2026	Dec. 31, 2025
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of Shares, Outstanding, Beginning Balance	9,098,233
Granted	7,435,819
Exercised	(421,313)
Canceled or forfeited	(424,184)
Number of Shares, Outstanding, Ending Balance	15,688,555	9,098,233
Vested and expected to vest	15,688,555
Vested and exercisable	5,935,504
Weighted Average Exercise Price per Share, Outstanding, Beginning Balance	$ 2.64
Weighted Average Exercise Price per Share, Granted	3.82
Weighted Average Exercise Price per Share, Exercised	1.83
Weighted Average Exercise Price per Share, Cancel or forfeited	2.18
Weighted Average Exercise Price per Share, Outstanding, Ending Balance	3.23	$ 2.64
Vested and expected to vest	3.23
Vested and exercisable	$ 2.93
Weighted Average Remaining Contractual Term, Outstanding	8 years 4 months 9 days	7 years 8 months 19 days
Weighted Average Remaining Contractual Term, Vested and expected to vest	8 years 4 months 9 days
Weighted Average Remaining Contractual Term, Vested and exercisable	7 years 1 month 13 days
Aggregate Intrinsic Value, Outstanding	$ 378,796	$ 3,386
Aggregate Intrinsic Value, Vested and expected to vest	378,796
Aggregate Intrinsic Value, Vested and exercisable	$ 145,130

Stockholders' Equity (Deficit)

6 Months Ended

Jun. 30, 2026

Equity [Abstract]

Stockholders' Equity (Deficit)

7. Stockholders’ Equity (Deficit)

Common Stock Warrants

The Company issued common stock warrants as part of the Loan Agreement (refer to Note 9, Term Loan) which were determined to be a freestanding instrument and met the criteria for equity classification as they are indexed to the Company’s own common stock and settled in a fixed number of shares for a fixed exercise price, with no cash settlement feature. As of December 31, 2025, warrants to purchase 24,152 shares of common stock with an exercise price of $4.82 per share were outstanding. In June 2026, the warrants were net exercised resulting in the issuance of 20,468 shares of common stock and no cash proceeds to the Company.

Common Stock and Non-Voting Common Stock

As of June 30, 2026, the Company’s certificate of incorporation authorized the issuance of 600,000,000 shares of common stock, 200,000,000 shares of non-voting common stock, and 10,000,000 shares of undesignated preferred stock, each with a par value of $0.0001 per share. As of June 30, 2026, 121,938,652 shares of common stock and 1,581,210 shares of non-voting common stock were outstanding.

In June 2026, the Company completed its IPO. In connection with the IPO, the Company issued and sold 38,525,000 shares of its common stock at a public offering price of $20.00 per share, including 5,025,000 shares of common stock sold pursuant to the underwriters’ full exercise of their option to purchase additional shares of common stock. As a result, the Company received $712.9 million in net proceeds, after deducting underwriting discounts and commissions and offering expenses of $57.6 million.

In connection with the IPO, the Company issued and sold 4,166,666 shares of its common stock in a concurrent private placement to Regeneron at a price per share of $18.00, or 90% of the public offering price, and received proceeds of $75.0 million (see Note 12, Collaboration Agreements).

In connection with the IPO, the SAFE automatically converted into 2,777,777 shares of common stock at a price per share of $18.00, or 90% of the public offering price (see Note 10, Simple Agreement for Future Equity).

The voting, dividend and liquidation rights of the holders of common stock and non-voting common stock are subject to and qualified by the rights, powers, and preferences of the holders of any outstanding preferred stock. Each share of common stock entitles the holder to one vote on all matters submitted to a vote of the Company’s stockholders. Holders of non-voting common stock are not entitled to any votes per share of non-voting common stock. Holders of common stock and non-voting common stock are entitled to receive dividends, as may be declared by the Board of Directors, if any, subject to the preferential dividend rights of holders of all series of any outstanding preferred stock. As of June 30, 2026, the Company has neither declared nor paid any dividends. Each share of non-voting common stock may be converted into one share of voting common stock at any time at the option of the holder, subject to certain beneficial ownership limitations.

The Company has reserved shares of common stock for the conversion or exercise of the following securities:


	June 30,		December 31,
	2026		2025
Series A Preferred Stock		—		1,002,805
Series B Preferred Stock		—		4,069,102
Series C Preferred Stock		—		6,540,022
Series D Preferred Stock		—		12,669,755
Series E Preferred Stock		—		15,128,745
Common stock warrants		—		24,152
Outstanding stock options		15,688,555		9,098,233
Unissued stock-based awards under the 2016 Employee, Director and Consultant Equity Incentive Plan		—		1,097,518
Unissued stock-based awards under the 2026 Stock Option and Incentive Plan		10,895,110		—
Unissued stock-based awards under the 2026 Employee Stock Purchase Plan		1,110,000		—
Total		27,693,665		49,630,332

The entire disclosure for equity.

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-Paragraph 1
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-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 22: http://www.xbrl.org/2003/role/disclosureRef
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Reference 23: http://www.xbrl.org/2003/role/disclosureRef
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Reference 24: http://www.xbrl.org/2003/role/disclosureRef
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Reference 25: http://www.xbrl.org/2003/role/disclosureRef
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Reference 26: http://www.xbrl.org/2003/role/disclosureRef
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Reference 27: http://www.xbrl.org/2003/role/disclosureRef
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Reference 28: http://www.xbrl.org/2003/role/disclosureRef
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Reference 29: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 30: http://www.xbrl.org/2003/role/disclosureRef
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Reference 31: http://www.xbrl.org/2003/role/disclosureRef
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Reference 34: http://www.xbrl.org/2003/role/disclosureRef
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Reference 35: http://www.xbrl.org/2003/role/disclosureRef
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Convertible Preferred Stock (Additional Information) (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended	6 Months Ended
	Jan. 06, 2026	Jun. 30, 2026	Jun. 30, 2026	Jun. 30, 2025	Dec. 31, 2025
Class of Stock [Line Items]
Preferred stock, shares issued		0	0		0
Price per share		$ 0.0001	$ 0.0001		$ 0.0001
Proceeds from issuance of convertible preferred stock		$ 811,800
Stock issuance cost			$ 680	$ 62
Dividend Income			$ 7,900
Preferred stock, shares outstanding		0	0		0
Series F Preferred Stock [Member]
Class of Stock [Line Items]
Price per share	$ 6.16
Convertible Preferred Stock, Shares Issued	49,518,175
Proceeds from issuance of convertible preferred stock	$ 305,200
Stock issuance cost	$ 700

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Amount of operating dividend income on securities.

Number of shares issued for nonredeemable preferred shares and preferred shares redeemable solely at option of issuer. Includes, but is not limited to, preferred shares issued, repurchased, and held as treasury shares. Excludes preferred shares classified as debt.

Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 11: http://www.xbrl.org/2009/role/commonPracticeRef
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Summary of Significant Accounting Policies - Schedule of Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Dec. 31, 2025	Jun. 30, 2025
Accounting Policies [Abstract]
Cash and cash equivalents	$ 1,087,060	$ 27,711	$ 80,394
Restricted cash - long-term	2,855	$ 2,855	2,855
Total cash, cash equivalents and restricted cash	$ 1,089,915		$ 83,249

Amount of cash restricted as to withdrawal or usage. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits.

Amount of cash and cash equivalent restricted as to withdrawal or usage. Cash includes, but is not limited to, currency on hand, demand deposit with financial institution, and account with general characteristic of demand deposit. Cash equivalent includes, but is not limited to, short-term, highly liquid investment that is both readily convertible to known amount of cash and so near maturity that it presents insignificant risk of change in value because of change in interest rate.

Property, Plant, and Equipment [Abstract]

Property and Equipment, Net (Tables)

6 Months Ended

Jun. 30, 2026

Schedule of Property And Equipment Net

Property and equipment, net consisted of the following (in thousands):


	June 30,			December 31,
	2026			2025
Laboratory equipment	$	14,348		$	13,830
Leasehold improvements		4,692			4,563
Computer equipment		609			307
Furniture and fixtures		745			697
Assets not yet in service		289			131
Property and equipment		20,683			19,528
Less: accumulated depreciation and amortization		(13,965	)		(12,813	)
Property and equipment, net	$	6,718		$	6,715

Summary of Significant Accounting Policies (Additional Information) (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Dec. 31, 2025	Jun. 30, 2025
Accounting Policies [Abstract]
Restricted cash - long-term	$ 2,855	$ 2,855	$ 2,855
Deferred offering costs	5,400	$ 600
Deferred Costs Current	$ 0

Net Loss Per Share

6 Months Ended

Jun. 30, 2026

Earnings Per Share [Abstract]

Net Loss Per Share

14. Net Loss Per Share

The following table sets forth the outstanding shares of common stock equivalents, presented based on amounts outstanding at each period end, which were excluded from the calculation of diluted net loss per share allocable to common stockholders for the periods indicated because including them would have been anti-dilutive:


	Three Months Ended June 30,				Six Months Ended June 30,
	2026		2025		2026		2025
Series A Preferred Stock		—		1,002,805		—		1,002,805
Series B Preferred Stock		—		4,069,102		—		4,069,102
Series C Preferred Stock		—		6,540,022		—		6,540,022
Series D Preferred Stock		—		12,669,755		—		12,669,755
Series E Preferred Stock		—		15,128,745		—		15,128,745
Common stock warrants		—		24,152		—		24,152
Outstanding stock options		15,269,049		8,607,087		15,269,049		8,607,087
Total		15,269,049		48,041,668		15,269,049		48,041,668

The amounts of outstanding stock options in the table above for the three and six months ended June 30, 2026 and 2025 exclude 419,506 potentially dilutive securities as these outstanding stock options relate to contingently issuable shares for which the market condition was not satisfied as of the respective period end.

Term Loan (Additional Information) (Details) - USD ($) $ in Millions	1 Months Ended	6 Months Ended
	Nov. 22, 2024	Jun. 30, 2026	Jun. 30, 2025	Dec. 31, 2025	Nov. 01, 2025	Sep. 21, 2021
Debt Instrument [Line Items]
Aggregate term loan		$ 0.1			$ 1.3	$ 15.0
Debt Instrument, Maturity Date		Oct. 01, 2026
Effective interest rate of the term loan		8.8	8.9
Debt instrument description		The term loan calls for an additional final payment equal to 4.5% of the aggregate principal amount borrowed, as well as a fee of approximately $0.1 million, due upon (a) the term loan maturity date, (b) the repayment of the term loan in full, (c) as required pursuant to permitted prepayment or mandatory prepayment upon an acceleration, or (d) the termination of the Loan Agreement.
Debt Instrument, Covenant Description	original debt agreement and the terms immediately after the amendment was less than 10%.
Line of credit facility maximum borrowing capacity	$ 60.0
Line of credit description	50.00%
Long Term Debt Noncurrent		$ 0.7		$ 0.6
Maximum [Member]
Debt Instrument [Line Items]
Debt Interest rate		6.75%
Percenatge of outstanding principal amount		3.00%
Minimum [Member]
Debt Instrument [Line Items]
Percenatge of outstanding principal amount		0.00%

Fair Value Measurements

6 Months Ended

Jun. 30, 2026

Fair Value Disclosures [Abstract]

Fair Value Measurements

The carrying values of cash, prepaid expenses and other current assets, accounts payable, due to related party and accrued expenses and other current liabilities approximate their fair values due to their short-term nature. The carrying value of the Company’s term debt (refer to Note 9, Term Loan) approximates its fair value due to its time to maturity.

The following tables present information about the Company’s financial assets measured at fair value on a recurring basis and indicate the level of the fair value hierarchy utilized to determine such fair values (in thousands):


	Fair Value Measurements as of June 30, 2026:
	Level 1		Level 2		Level 3		Total
Assets
Cash equivalents:
Money market funds	$	1,075,747	$	—	$	—	$	1,075,747
U.S. Treasury bills		—		9,999		—		9,999
Marketable securities:
U.S. Treasury bills		—		33,637		—		33,637
Total assets	$	1,075,747	$	43,636	$	—	$	1,119,383


	Fair Value Measurements as of December 31, 2025:
	Level 1		Level 2		Level 3		Total
Assets
Cash equivalents:
Money market funds	$	27,133	$	—	$	—	$	27,133
Total assets	$	27,133	$	—	$	—	$	27,133

During the six months ended June 30, 2026 and 2025, there were no transfers among the Level 1, Level 2 and Level 3 categories.

Money market funds are classified within Level 1 of the fair value hierarchy as they are highly liquid investments based on a quoted price with a net asset value of $1 per share.

The fair values of the Company’s marketable securities are based on prices obtained from independent pricing sources. Marketable securities with validated quotes from pricing services are reflected within Level 2 of the fair value hierarchy as they are primarily based on observable pricing for similar assets or other market observable inputs. Typical inputs used by these pricing services include, but are not limited to, reported trades, benchmark yields, issuer spreads, bids, offers or estimates of cash flow, prepayment spreads and default rates.

The following table summarizes the gross unrealized gains and losses of the Company’s marketable securities (in thousands):


	June 30, 2026
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Marketable securities:
U.S. Treasury bills	$	33,655	$	—	$	(18	)	$	33,637

As of June 30, 2026, all of the Company’s marketable securities had remaining contractual maturities of less than one year. As of June 30, 2026, the Company held three securities that were in an unrealized loss position for less than 12 months with an aggregate fair value of $33.6 million. The Company does not intend to sell such securities and it is not more likely than not that it will be required to sell them before recovery of their amortized cost basis. The Company held no marketable securities as of December 31, 2025.

As of June 30, 2026 and December 31, 2025, there was no allowance for credit losses recorded on the Company’s condensed consolidated balance sheets.

Valuation of Preferred Stock Tranche Right Liability

The preferred stock tranche right liability represented the fair value of an obligation to issue shares of Series E convertible preferred stock. The fair value of the preferred stock tranche right liability was determined based on significant inputs not observable in the market, which represented a Level 3 measurement within the fair value hierarchy.

The Company estimated the fair value of the preferred stock tranche right liability at the time of issuance and subsequently remeasured its fair value at each reporting period and prior to settlement.

As of December 31, 2024, in light of the near-term completion of the Series E convertible preferred stock second closing in January 2025, the fair value of the preferred stock tranche right liability was determined based on the difference between the estimated fair value of the Series E convertible preferred stock, or $6.43 per share, and its contractual purchase price, or $6.23 per share. The Company estimated the fair value per share of the underlying Series E convertible preferred stock by taking into consideration the results obtained from third-party valuations which included the most recent sales of its preferred stock, market conditions and trends since the last preferred stock issuance.

The following table presents changes in the aggregate fair value of the Company’s Series E preferred stock tranche right liability (in thousands):


	Amount
Balance as of December 31, 2024	$	2,167
Settlement of Series E preferred stock tranche right liability		(2,167	)
Balance as of June 30, 2025	$	—

Valuation of Simple Agreement for Future Equity

On March 27, 2026, the Company issued a SAFE to an investor (refer to Note 10, Simple Agreement for Future Equity). The SAFE was accounted for as a liability and represented a Level 3 measurement within the fair value hierarchy.

The fair value of the SAFE upon issuance was determined to be equal to the proceeds received of $50.0 million. In connection with the IPO, the SAFE automatically converted into 2,777,777 shares of common stock based on the IPO Discount Price (see Note 10, Simple Agreement for Future Equity) of $18.00 per share. The fair value of the SAFE upon conversion was determined to be $55.6 million based on the fair value of the common stock issued upon conversion.

The following table presents changes in the aggregate fair value of the SAFE (in thousands):


	Amount
Balance as of December 31, 2025	$	—
Fair value of SAFE at issuance		50,000
Change in fair value of SAFE		5,556
Conversion of SAFE into common stock		(55,556	)
Balance as of June 30, 2026	$	—

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/exampleRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Stockholders' Equity Note [Abstract]

Convertible Preferred Stock (Tables)

6 Months Ended

Jun. 30, 2026

Summary of Convertible Preferred Stock Except Share and Per Share Amounts

Convertible preferred stock consisted of the following at December 31, 2025 (in thousands, except share and per share amounts):


	Shares of Preferred Stock Authorized		Original Issuance Price Per Share		Shares of Preferred Stock Issued and Outstanding		Carrying Value		Liquidation Preference		Shares of Common Stock Issuable Upon Conversion
Series A		1,434,062	$	7.75		1,434,062	$	14,914	$	19,477		1,002,805
Series B		4,658,112	$	14.06		4,658,112		65,388		106,351		4,069,102
Series C		7,384,710	$	14.49		7,384,710		106,674		152,175		6,540,022
Series D		16,537,979	$	10.76		16,537,979		177,581		225,956		12,669,755
Series E		23,281,563	$	6.23		23,281,563		145,414		155,013		15,128,745
		53,296,426				53,296,426	$	509,971	$	658,972		39,410,429

Summary of the significant Level 3 Unobservable Inputs

The following table summarizes the significant Level 3 unobservable inputs used to estimate the fair value of the Series A Preferred Stock, Series B Preferred Stock, Series C Preferred Stock, Series D Preferred Stock and Series E Preferred Stock at the Series F Preferred Stock issuance date:


		January 6, 2026
Expected volatility		78.0%
Expected dividend yield		—
Expected term (in years)		0.85 - 2.5
Risk-free interest rate		3.6%

Summary of Convertible Preferred Stock Shares Conversation Table Text Block

Upon the closing of the IPO, each series of convertible preferred stock was converted into common stock and non-voting common stock, as follows:


	Shares of Common Stock Issued Upon Conversion		Shares of Non-Voting Common Stock Issued Upon Conversion
Series A		1,062,074	—
Series B		4,839,338	—
Series C		7,811,705	—
Series D		14,493,574	—
Series E		15,188,963	—
Series F		30,596,417		1,581,210
		73,992,071		1,581,210

Related Party Transactions (Additional Information) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Related Party Transaction [Line Items]
Related Party Transaction, Description of Transaction			In December 2019, the Company entered into a non-cancelable sublease arrangement with a related party to sublease approximately 50% of the Company’s leased space at 30 Acorn Park Drive in Cambridge, Massachusetts through February 2025
Percentage of Related Party to Sublease			50.00%
Sublease income - related party	$ 0	$ 1,057	$ 0	$ 2,114
Proceeds from Related Party Debt		500		1,100
Research and development cost	39,377	30,126	77,130	64,031
General and administrative	$ 11,657	6,394	$ 21,357	12,730
Related Party [Member]
Related Party Transaction [Line Items]
Research and development cost		500		1,000
General and administrative		$ 100		$ 100

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Organization, Consolidation and Presentation of Financial Statements [Abstract]

Collaboration Agreements

6 Months Ended

Jun. 30, 2026

Collaboration Agreements

12. Collaboration Agreements

Research Collaboration Agreement with ARTBIO, Inc.

In May 2024, the Company entered into a research collaboration agreement with ARTBIO, Inc. (“ARTBIO”) to co-develop multiple Helicon-enabled alpha particle radioligand therapies (HEARTs) for the treatment of cancer. Under the terms of this agreement, the Company is responsible for equally participating on joint committees and carrying out at least four research programs with respect to each collaboration target. The Company and ARTBIO share in the costs of the research programs equally, with ARTBIO responsible for funding the first $10.0 million of development costs incurred by both parties and the Company responsible for funding the next $10.0 million of development costs. Any further development costs beyond these initial funding amounts will also be shared equally by both parties. Under certain circumstances, either party can terminate the agreement, or opt out of further participation in any research programs, and the Company may be obligated to refund, to ARTBIO, amounts received during the initial funding periods, such that the total costs incurred through the effective date of termination would be shared equally.

Upon later regulatory approval and commercialization of related product(s), the parties will share equally in all net profits or losses. The agreement expires upon (1) the date on which products arising from the collaboration are no longer commercialized or developed for commercialization, or (2) termination by one or both parties.

The Company determined the agreement was a collaboration arrangement under ASC Topic 808, Collaborative Arrangements. The agreement provides for the parties to jointly oversee and actively participate in the research and development activities under the agreement. In addition, both parties are exposed to the significant risks and potential rewards under the agreement.

No costs were incurred by the Company during the three and six months ended June 30, 2026. During the three and six months ended June 30, 2025, the Company incurred $0.8 million and $2.4 million, respectively, in costs related to the research programs within the scope of the agreement, which have been fully reimbursed by ARTBIO. Pursuant to the contract termination and funding provisions noted above, and based on the current development plan, the Company recorded a liability representing its portion of the research and development expense incurred to date. No increase in the liability balance was recorded during the three and six months ended June 30, 2026. During the three and six months ended June 30, 2025, the Company recorded increases to the liability of $0.5 million and $1.4 million, respectively. The Company recorded the remaining amount of $0.3 million and $1.0 million as a reduction of research and development expenses within the condensed consolidated statements of operations and comprehensive loss for the three and six months ended June 30, 2025, respectively. As of June 30, 2026 and December 31, 2025, the liability balance totaled $2.7 million and is classified in accrued expenses and other current liabilities and other liabilities, respectively, on the condensed consolidated balance sheets.

On April 16, 2026, ARTBIO sent notice of its intent to opt out of all the research programs under the research collaboration agreement. On May 26, 2026, the Company sent a notice of termination of the research collaboration agreement to ARTBIO. No eligible costs were incurred by the Company or ARTBIO during the six months ended June 30, 2026.

License and Collaboration Agreement with Regeneron

On May 15, 2026, the Company entered into the Regeneron Agreement with Regeneron to discover, develop, and commercialize Helicons, with a particular focus on Antibody-Helicon Conjugates (“AHCs”), directed to a set of specified targets (each, a “Collaboration Target”).

Under the terms of the Regeneron Agreement and during the research term for each Collaboration Target, the Company will perform certain research and preclinical development activities, including screening, generating, testing and evaluating new Helicons and AHCs directed to such Collaboration Target (each, a “Product”). Under the Regeneron Agreement, there are five initial Collaboration Targets, with Regeneron having the right to replace up to two targets for no additional consideration and the option to nominate up to five additional Collaboration Targets, subject to an additional option payment from Regeneron. For one initial

Collaboration Target, Regeneron may add one or more additional programs with respect to such Collaboration Target, subject to payment of additional program fees. Following Regeneron’s nomination of a Product to be a “Licensed Product” during the research term for the applicable Collaboration Target (including additional Collaboration Targets), Regeneron has the sole right to advance through development, manufacturing and worldwide commercialization of Licensed Products, including clinical and regulatory strategy, pricing, and promotion.

Under the terms of the Regeneron Agreement, Regeneron agreed to make a $50.0 million upfront payment, which the Company received in June 2026, and invest $75.0 million in the Company's next equity financing if such financing occurred prior to the second anniversary of the execution of the Regeneron Agreement (the “Regeneron Equity Commitment”). The IPO triggered Regeneron’s $75.0 million equity investment whereby Regeneron purchased 4,166,666 shares of common stock in a concurrent private placement at a per share price equal to 90% of the public offering price, or $18.00 per share. For the initial Collaboration Targets, the Company is eligible to receive: (i) up to $470.0 million in development milestone payments; (ii) up to $575.0 million in regulatory milestone payments; (iii) up to $1.15 billion in commercial milestone payments; and (iv) tiered royalty payments, ranging in the high single digits to low double digits during the period commencing upon the first commercial sale of such Licensed Product in a given country and expiring on the latest of: (a) expiration of the last valid claim of a royalty term-extending patent right of such Licensed Product in such country, (b) 12 years after the first commercial sale of such Licensed Product in such country, and (c) loss of regulatory exclusivity for such Licensed Product in such country, subject to customary reductions.

Under the terms of the Regeneron Agreement, the Company is subject to an exclusivity obligation for each Collaboration Target until the last to expire royalty term for Licensed Products directed to such Collaboration Target. Unless earlier terminated pursuant to its terms, the Regeneron Agreement will remain in effect until the expiration of the last royalty term for the last Licensed Product under the Regeneron Agreement. Regeneron has the right to terminate the Regeneron Agreement for convenience and for certain violations of the Company’s exclusivity covenants.

The Company determined that the Regeneron Agreement represents a contract with a customer within the scope of ASC 606. ASC 606 requires that share based consideration granted to a customer in connection with a revenue transaction be accounted for under ASC 718. More specifically, the discount associated with the Regeneron Equity Commitment of $8.3 million was accounted for in accordance with the guidance in ASC 718 and was recognized as a reduction of the ASC 606 transaction price upon the completion of the Company’s IPO. The Company recorded the common stock issued in conjunction with the Regeneron Equity Commitment at its fair value of $83.3 million.

The Company identified the following promises under the agreement: (i) exclusive licenses granted to Regeneron for each Collaboration Target (the “Exclusive License”) and (ii) preclinical research and development services for each Collaboration Target (the “Research Services”). In addition, the Company concluded that Regeneron’s right to replace up to two Collaboration Targets (each, a “Replacement Collaboration Target”) for no additional consideration represents material rights under the agreement.

The Company concluded that the Exclusive License and Research Services for each Collaboration Target should be combined into one performance obligation as the licenses are not capable of being distinct. Regeneron can only benefit from the license with the services to be provided by the Company which are specialized in nature. Further, the specialized services, which include the Company’s expertise using its Helicon platform to identify potential binding sites and Helicons that are capable of binding to such sites, further modify and enhance the exclusive license such that the exclusive license is not distinct in the context of the contract. As such, the Company has identified five performance obligations related to each of the five Collaboration Targets that include the combined obligation to provide an exclusive license and research services and two performance obligations related to the material right to replace two Collaboration Targets.

The transaction price, which subsequent to the recognition of the Regeneron Equity Commitment is $41.7 million, was allocated to the performance obligations on a relative selling price basis. As of June 30, 2026, the aggregate amount of the transaction price allocated to unsatisfied or partially unsatisfied performance obligations was $41.5 million. The Company expects to recognize this amount as collaboration revenue through at least 2029, although the timing of recognition will depend on the performance of the research services and the exercise or expiration of the replacement-target rights.

The Company determined the estimated standalone selling price for each Exclusive License and Research Services performance obligation using a discounted cash flow model that determined the present value of the probability weighted cash inflows and outflows associated with each Collaboration Target. The Company determined the estimated standalone selling price for material rights by estimating the incremental costs to perform the additional services and estimating the probability the replacement right will be exercised. For sales-based milestones and royalties, the Company will recognize revenue when the underlying product revenue is recognized by Regeneron. All other contingent payments are fully constrained as of June 30, 2026, as the achievement of the milestones underlying such contingent payments is based on either the Company or Regeneron’s ability to execute under the research plans, which is not certain at contract inception.

Revenue associated with the Exclusive License and Research Services performance obligations is recognized as the underlying services are provided as control is transferred over time. The Company measures progress based on the amount of costs incurred relative to the total costs expected to fulfill the combined performance obligation. In management’s judgment, this input method is the

best measure of progress towards satisfying the combined performance obligation and reflects a faithful depiction of the transfer of goods and services. Revenue associated with the material rights will be recognized upon expiry if the option is not exercised. The amounts allocated to the material rights, if exercised, will be recognized over the period of performance of the underlying performance obligations.

During the three and six months ended June 30, 2026, the Company recognized revenue of $0.1 million. Deferred revenue as of June 30, 2026 was $41.5 million, of which $10.4 million was recorded as a current liability on the condensed consolidated balance sheet.

Fair Value Measurements - Schedule of Changes in the Aggregate Fair Value (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Abstract]
Beginning Balance	$ 0	$ 2,167
Settlement of Series E preferred stock tranche right liability	0	(2,167)
Fair value of SAFE at issuance	50,000
Change in fair value of SAFE	5,556
Conversion of SAFE into common stock	(55,556)
Ending Balance	$ 0	$ 0

Convertible Preferred Stock

6 Months Ended

Jun. 30, 2026

Stockholders' Equity Note [Abstract]

Convertible Preferred Stock

6. Convertible Preferred Stock

On January 6, 2026, the Company entered into the Series F Preferred Stock Purchase Agreement (the “Series F Agreement”) and issued to certain investors an aggregate of 49,518,175 shares of Series F convertible preferred stock (the “Series F Preferred Stock”) at a purchase price of $6.16 per share for gross proceeds of $305.2 million. The gross proceeds were offset by $0.7 million of issuance costs.

In accordance with the terms of the Company’s certificate of incorporation, the issuance of the Series F Preferred Stock triggered adjustments to the respective conversion prices of the Series A convertible preferred stock (the “Series A Preferred Stock”), the Series B convertible preferred stock (the “Series B Preferred Stock”), the Series C convertible preferred stock (the “Series C Preferred Stock”), the Series D convertible preferred stock (the “Series D Preferred Stock”) and the Series E convertible preferred stock (the “Series E Preferred Stock”) (as described further below). As a result, the Company recorded an increase to additional paid-in capital and a deemed dividend of $7.9 million which is equal to the change in fair value of the Series A Preferred Stock, Series B Preferred Stock, Series C Preferred Stock, Series D Preferred Stock and Series E Preferred Stock due to the triggering of the down-round feature. As the Company did not have retained earnings at the time the Series F Preferred Stock was issued, the deemed dividend was charged against additional paid-in capital resulting in no net impact to additional paid-in capital. The fair value of each preferred share class was determined using a “with-and-without” model under which the equity value of the Company was allocated using a hybrid method, whereby the equity value in the IPO scenario was allocated to each class of shares using the fully-diluted shares outstanding and whereby the equity value in the non-IPO scenario was allocated using an option-pricing model to reflect the full distribution of possible non-IPO outcomes, both before and after the adjustment to the respective conversion price. The following table summarizes the significant Level 3 unobservable inputs used to estimate the fair value of the Series A Preferred Stock, Series B Preferred Stock, Series C Preferred Stock, Series D Preferred Stock and Series E Preferred Stock at the Series F Preferred Stock issuance date:


		January 6, 2026
Expected volatility		78.0%
Expected dividend yield		—
Expected term (in years)		0.85 - 2.5
Risk-free interest rate		3.6%

Upon the issuance of each series of convertible preferred stock, the Company assessed the embedded conversion and liquidation features of the securities and determined that the Company was not required to separately account for these features.

Convertible preferred stock consisted of the following at December 31, 2025 (in thousands, except share and per share amounts):


	Shares of Preferred Stock Authorized		Original Issuance Price Per Share		Shares of Preferred Stock Issued and Outstanding		Carrying Value		Liquidation Preference		Shares of Common Stock Issuable Upon Conversion
Series A		1,434,062	$	7.75		1,434,062	$	14,914	$	19,477		1,002,805
Series B		4,658,112	$	14.06		4,658,112		65,388		106,351		4,069,102
Series C		7,384,710	$	14.49		7,384,710		106,674		152,175		6,540,022
Series D		16,537,979	$	10.76		16,537,979		177,581		225,956		12,669,755
Series E		23,281,563	$	6.23		23,281,563		145,414		155,013		15,128,745
		53,296,426				53,296,426	$	509,971	$	658,972		39,410,429

Upon the closing of the IPO, each series of convertible preferred stock was converted into common stock and non-voting common stock, as follows:


	Shares of Common Stock Issued Upon Conversion		Shares of Non-Voting Common Stock Issued Upon Conversion
Series A		1,062,074	—
Series B		4,839,338	—
Series C		7,811,705	—
Series D		14,493,574	—
Series E		15,188,963	—
Series F		30,596,417		1,581,210
		73,992,071		1,581,210

Simple Agreement for Future Equity

6 Months Ended

Jun. 30, 2026

Equity [Abstract]

Simple Agreement for Future Equity

10. Simple Agreement for Future Equity

On March 27, 2026, the Company issued a SAFE to an investor for gross proceeds of $50.0 million. The SAFE had no interest rate or maturity date. The SAFE investor had no voting rights prior to conversion, and if the Company paid a dividend on outstanding shares of its common stock while the SAFE was outstanding, the investor would have also received a dividend.

The SAFE was automatically convertible into the number of shares of common stock obtained by dividing (i) $50.0 million by (ii) the IPO Discount Price upon the closing of an IPO. The “IPO Discount Price” in connection with an IPO was the offering price in the IPO (the “IPO Price”) multiplied by 90% (such product, the “Initial IPO Discount Price”), provided that (i) if the IPO Price was greater than or equal to $9.4864 per share, and (ii) the Initial IPO Discount Price was equal to or less than $9.4864 per share, then the IPO Discount Price would have equaled $9.4864 per share; and provided further that if the IPO Price was less than $9.4864, the IPO Discount Price would have equaled the IPO Price. The SAFE was also automatically convertible into preferred stock or common stock upon an equity financing other than an IPO based on similar conversion terms and discount rate.

The Company concluded the SAFE was a freestanding financial instrument that required liability classification pursuant to the guidance in ASC Topic 480, Distinguishing Liabilities from Equity, as it embodied a conditional obligation to issue a variable number of shares based predominantly on a fixed monetary amount known at inception. The SAFE was initially recorded at fair value upon the issuance date, with subsequent changes in fair value recorded in the condensed consolidated statements of operations and comprehensive loss at each reporting date. The fair value of the SAFE at issuance was $50.0 million. In connection with the IPO, the SAFE automatically converted into 2,777,777 shares of common stock based on the IPO Discount Price of $18.00 per share. The fair value of the SAFE upon conversion was determined to be $55.6 million based on the fair value of the common stock issued upon conversion.

Commitments and Contingencies

6 Months Ended

Jun. 30, 2026

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

11. Commitments and Contingencies

Harvard Agreement

In August 2017, the Company entered into a license agreement, as amended (the “Harvard Agreement”), with the President and Fellows of Harvard College (“Harvard”), to obtain a worldwide, exclusive, royalty-bearing license to certain intellectual property which was developed by the Company’s founder.

Under the terms of the Harvard Agreement, the Company is required to make payments to Harvard upon the achievement of certain development, regulatory and sales milestones up to an aggregate of $18.3 million, as well as future royalty payments, based on a percentage of aggregate net sales ranging in the low single digits. In addition, the Company is required to make payments to Harvard for non-royalty income received under sublicenses or strategic partnerships with third parties, with the applicable payment based on the stage of development of the first licensed product at the time the Company enters into such agreement (before or after enrollment of the first patient in a Phase 2 clinical study of a licensed product), ranging from a single-digit percentage to a mid-teens percentage. During the year ended December 31, 2025, the Company met one milestone of $0.2 million which is included in accounts payable on the condensed consolidated balance sheet as of December 31, 2025 and which the Company paid during the six months ended June 30, 2026. As of June 30, 2026, the Company has achieved milestones totaling $0.3 million under the Harvard Agreement. None of the remaining milestones were deemed probable of achievement as of June 30, 2026.

The Company is also required to pay a low six-digit annual maintenance fee for the duration of the Harvard Agreement, which can be credited against future royalty payments.

Legal Proceedings

From time to time, the Company may become involved in legal proceedings or other litigation relating to claims arising in the ordinary course of business. The Company accrues a liability for such matters when it is probable that future expenditures will be made and that such expenditures can be reasonably estimated. Legal fees and other costs associated with such proceedings are expensed as incurred. As of June 30, 2026 and December 31, 2025, the Company was not a party to any material legal proceedings or claims.

Indemnification Agreements

In the ordinary course of business, the Company may provide indemnification of varying scope and terms to vendors, lessors, business partners and other parties with respect to certain matters including, but not limited to, losses arising out of breach of such agreements or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with members of its Board of Directors that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is, in many cases, unlimited. To date, the Company has not incurred any material costs as a result of such indemnifications. The Company is not aware of any indemnification arrangements that could have a material effect on its financial position, results of operations or cash flows, and it has not accrued any liabilities related to such obligations in its condensed consolidated financial statements as of June 30, 2026 and December 31, 2025.

Retirement Plan (Additional Information) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Retirement Benefits [Abstract]
Matching contributions amount	$ 0.3	$ 0.3	$ 0.8	$ 0.7

Segment Reporting (Tables)

6 Months Ended

Jun. 30, 2026

Segment Reporting [Abstract]

Schedule of Segment Information

The following table presents selected financial information with respect to the Company’s single operating segment (in thousands):


	Three Months Ended June 30,						Six Months Ended June 30,
	2026			2025			2026			2025
Collaboration revenue	$	148		$	—		$	148		$	—
Operating expenses:
External research and development expense - Zolucatetide		12,673			9,379			25,767			22,524
External research and development expense - ß-Catenin Degrader		799			193			1,215			912
External research and development expense - ERG		1,970			1,842			4,882			3,482
External research and development expense - ARON		1,959			751			3,365			1,616
External research and development expense - Early discovery and other programs		1,021			1,245			2,015			2,239
Other research and development expenses		8,319			7,462			15,969			14,034
Personnel-related research and development expenses (excluding stock-based compensation expense)		11,362			8,471			21,594			17,609
Personnel-related general and administrative expenses (excluding stock-based compensation expense)		2,487			2,252			5,596			4,663
Other general and administrative expenses		6,217			3,484			11,947			6,735
Depreciation and amortization expense		593			618			1,199			1,272
Stock-based compensation expense		3,634			823			4,938			1,675
Other segment items(1)		1,577			(1,710	)		(560	)		(3,625	)
Consolidated net loss	$	(52,463	)	$	(34,810	)	$	(97,779	)	$	(73,136	)

Notes

(1)

Other segment items consist of interest income, interest expense, sublease income – related party, and change in fair value of simple agreement for future equity.

Tabular disclosure of segment reporting. Includes, but is not limited to, reconciliation of reportable segment amount to corresponding consolidated total.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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-SubTopic 10
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Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 7: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef
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Schedule of Calculation of Diluted Net Loss Per Share Allocable to Common Stockholders

Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Dec. 31, 2025
Other Liabilities Disclosure [Abstract]
Accrued employee compensation and benefits	$ 5,459	$ 9,079
Accrued research and development expenses	8,888	8,334
Accrued offering costs	1,399	491
Other	4,226	726
Total	$ 19,972	$ 18,630

Commitments and Contingencies (Additional Information) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2026	Dec. 31, 2025
Long-Term Purchase Commitment [Line Items]
Material legal proceedings	$ 0.0	$ 0.0
Harvard Agreement [Member]
Long-Term Purchase Commitment [Line Items]
Payments to achievement of certain development	18.3
Accounts Payable		0.2
Achieved milestones	0.3
Indemnification Agreements [Member]
Long-Term Purchase Commitment [Line Items]
Accrued Liabilities	$ 0.0	$ 0.0

Fair Value Measurements - Schedule of Gross Unrealized Gains and Losses of Marketable Securities (Details) - U.S. Treasury bills $ in Thousands	Jun. 30, 2026 USD ($)
Marketable Security, Gain (Loss) [Abstract]
Amortized Cost	$ 33,655
Unrealized Gains	0
Unrealized Losses	(18)
Marketable Securities	$ 33,637

Net Loss Per Share (Tables)

6 Months Ended

Jun. 30, 2026

Earnings Per Share [Abstract]


	Three Months Ended June 30,				Six Months Ended June 30,
	2026		2025		2026		2025
Series A Preferred Stock		—		1,002,805		—		1,002,805
Series B Preferred Stock		—		4,069,102		—		4,069,102
Series C Preferred Stock		—		6,540,022		—		6,540,022
Series D Preferred Stock		—		12,669,755		—		12,669,755
Series E Preferred Stock		—		15,128,745		—		15,128,745
Common stock warrants		—		24,152		—		24,152
Outstanding stock options		15,269,049		8,607,087		15,269,049		8,607,087
Total		15,269,049		48,041,668		15,269,049		48,041,668

Segment Reporting

6 Months Ended

Jun. 30, 2026

Segment Reporting [Abstract]

Segment Reporting

16. Segment Reporting

The Company manages its operations as a single operating and reportable segment that is focused on developing Helicon medicines targeting historically undruggable proteins. The CODM manages the Company’s operations on a consolidated basis and uses consolidated net loss to assess financial performance and allocate resources. Consolidated net loss is used by the CODM to make key operating decisions, such as the determination of the rate at which the Company seeks to grow its research and development initiatives and the allocation of capital between research and development and general and administrative expenses. The CODM does not review assets in evaluating the results of the segment, and therefore, such information is not presented.

The following table presents selected financial information with respect to the Company’s single operating segment (in thousands):


	Three Months Ended June 30,						Six Months Ended June 30,
	2026			2025			2026			2025
Collaboration revenue	$	148		$	—		$	148		$	—
Operating expenses:
External research and development expense - Zolucatetide		12,673			9,379			25,767			22,524
External research and development expense - ß-Catenin Degrader		799			193			1,215			912
External research and development expense - ERG		1,970			1,842			4,882			3,482
External research and development expense - ARON		1,959			751			3,365			1,616
External research and development expense - Early discovery and other programs		1,021			1,245			2,015			2,239
Other research and development expenses		8,319			7,462			15,969			14,034
Personnel-related research and development expenses (excluding stock-based compensation expense)		11,362			8,471			21,594			17,609
Personnel-related general and administrative expenses (excluding stock-based compensation expense)		2,487			2,252			5,596			4,663
Other general and administrative expenses		6,217			3,484			11,947			6,735
Depreciation and amortization expense		593			618			1,199			1,272
Stock-based compensation expense		3,634			823			4,938			1,675
Other segment items(1)		1,577			(1,710	)		(560	)		(3,625	)
Consolidated net loss	$	(52,463	)	$	(34,810	)	$	(97,779	)	$	(73,136	)

Notes

(1)

Other segment items consist of interest income, interest expense, sublease income – related party, and change in fair value of simple agreement for future equity.

The entire disclosure for segment reporting.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 24: http://www.xbrl.org/2003/role/disclosureRef
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Summary of Significant Accounting Policies

6 Months Ended

Jun. 30, 2026

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

The Company’s significant accounting policies are disclosed in Note 2 of the “Notes to Consolidated Financial Statements” in the audited annual financial statements included in the Company’s final prospectus filed with the Securities and Exchange Commission (the “SEC”) pursuant to Rule 424(b)(4) on June 10, 2026. During the six months ended June 30, 2026, there were no material changes to the Company’s significant accounting policies, except as discussed below.

Use of Estimates

Cash and Cash Equivalents


	June 30,
	2026		2025
Cash and cash equivalents	$	1,087,060	$	80,394
Restricted cash – long-term		2,855		2,855
Total cash, cash equivalents and restricted cash	$	1,089,915	$	83,249

Restricted Cash

As of June 30, 2026 and December 31, 2025, restricted cash consists of $2.9 million serving as collateral for a letter of credit required under the Company’s facility lease arrangement.

Concentration of Risk

Stock-Based Compensation

Revenue Recognition

Deferred Offering Costs

Net Loss Per Share

Segment Information

Recently Issued Accounting Pronouncements Not Yet Adopted

Recently Adopted Accounting Pronouncements

Stock-Based Compensation (Additional Information) (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	6 Months Ended
	May 31, 2026	Jun. 30, 2026	Jun. 30, 2025	Jan. 06, 2026	Dec. 31, 2025
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common stock, shares authorized		600,000,000			81,000,000
Common Stock Shares, Reserved		27,693,665			49,630,332
Weighted average grant date fair value per share		$ 2.92	$ 1.89
Intrinsic value		$ 2,500	$ 100
Proceeds from exercise of stock options		771	$ 9
Total unrecognized compensation expense related to unvested stock options		$ 22,300
Recognize compensation over a weighted-average period		3 years 1 month 6 days
Common Stock [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common stock, shares authorized		600,000,000
2016 Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common stock, shares authorized					10,826,224
Common Stock Shares, Reserved					10,826,224
2026 Stock Option and Grant Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common stock, shares authorized				8,873,223
Common Stock Shares, Reserved				8,873,223
2026 Stock Option and Incentive Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common stock, shares authorized	11,070,000
Common Stock Shares, Reserved	11,070,000	10,895,110
Shares increase	5.00%
2026 Employee Stock Purchase Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common Stock Shares, Reserved	1,110,000	1,110,000
Shares increase	1.00%
2026 Employee Stock Purchase Plan [Member] \| Common Stock [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of Shares	1,110,000
Stock Option Valuation [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Granted fair value adjustment		$ 500
Total unrecognized compensation expense related to unvested stock options		$ 200
Recognize compensation over a weighted-average period		8 months 12 days
Stock-based compensation expense	$ 1,100
Number of shares option to purchase	71,479

Property and Equipment, Net - Schedule of Property And Equipment Net (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Dec. 31, 2025
Property, Plant, and Equipment, after Accumulated Depreciation, Depletion, and Amortization [Abstract]
Laboratory equipment	$ 14,348	$ 13,830
Leasehold improvements	4,692	4,563
Computer equipment	609	307
Furniture and fixtures	745	697
Assets not yet in service	289	131
Property and equipment	20,683	19,528
Less: accumulated depreciation and amortization	(13,965)	(12,813)
Property and equipment, net	$ 6,718	$ 6,715

Amount of accumulated depreciation, depletion, and amortization of property, plant, and equipment. Includes, but is not limited to, land and land improvement; building; machinery and equipment; furniture and fixture; and work of art, historical treasure, or similar asset classified as collection.

Amount, after accumulated depreciation, depletion, and amortization, of property, plant, and equipment. Includes, but is not limited to, land and land improvement; building; machinery and equipment; furniture and fixture; and work of art, historical treasure, or similar asset classified as collection.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Share-Based Payment Arrangement [Abstract]

Convertible Preferred Stock - Convertible Preferred Stock was Converted into Common Stock and Non-Voting Common Stock (Details) - shares	Jun. 30, 2026	Jan. 06, 2026
Common Stock [Member]
Class of Stock [Line Items]
Convertible Preferred Stock, Shares Issued	73,992,071
Non-Voting Common Stock [Member]
Class of Stock [Line Items]
Convertible Preferred Stock, Shares Issued	1,581,210
Series A Preferred Stock [Member] \| Common Stock [Member]
Class of Stock [Line Items]
Convertible Preferred Stock, Shares Issued	1,062,074
Series A Preferred Stock [Member] \| Non-Voting Common Stock [Member]
Class of Stock [Line Items]
Convertible Preferred Stock, Shares Issued	0
Series B Preferred Stock [Member] \| Common Stock [Member]
Class of Stock [Line Items]
Convertible Preferred Stock, Shares Issued	4,839,338
Series B Preferred Stock [Member] \| Non-Voting Common Stock [Member]
Class of Stock [Line Items]
Convertible Preferred Stock, Shares Issued	0
Series C Preferred Stock [Member] \| Common Stock [Member]
Class of Stock [Line Items]
Convertible Preferred Stock, Shares Issued	7,811,705
Series C Preferred Stock [Member] \| Non-Voting Common Stock [Member]
Class of Stock [Line Items]
Convertible Preferred Stock, Shares Issued	0
Series D Preferred Stock [Member] \| Common Stock [Member]
Class of Stock [Line Items]
Convertible Preferred Stock, Shares Issued	14,493,574
Series D Preferred Stock [Member] \| Non-Voting Common Stock [Member]
Class of Stock [Line Items]
Convertible Preferred Stock, Shares Issued	0
Series E Preferred Stock [Member] \| Common Stock [Member]
Class of Stock [Line Items]
Convertible Preferred Stock, Shares Issued	15,188,963
Series E Preferred Stock [Member] \| Non-Voting Common Stock [Member]
Class of Stock [Line Items]
Convertible Preferred Stock, Shares Issued	0
Series F Preferred Stock [Member]
Class of Stock [Line Items]
Convertible Preferred Stock, Shares Issued		49,518,175
Series F Preferred Stock [Member] \| Common Stock [Member]
Class of Stock [Line Items]
Convertible Preferred Stock, Shares Issued	30,596,417
Series F Preferred Stock [Member] \| Non-Voting Common Stock [Member]
Class of Stock [Line Items]
Convertible Preferred Stock, Shares Issued	1,581,210

Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2026

Schedule of stock option granted using the Black-Scholes option-pricing mode and assumptions

The fair value of each stock option granted was estimated on the date of grant using the Black-Scholes option-pricing model and the assumptions summarized in the following table:


	Three Months Ended June 30,		Six Months Ended June 30,
	2026	2025	2026	2025
Expected volatility	89.70% - 90.12%	92.88%	89.70% - 90.15%	92.88% - 93.00%
Expected dividend yield	—	—	—	—
Expected term (in years)	5.50 - 6.25	6.25	5.50 - 6.25	6.25
Risk-free interest rate	3.98% - 4.29%	4.04%	3.70% - 4.29%	4.04%
Fair value of common stock	$4.09 - $20.00	$2.42	$3.14 - $20.00	$2.42

Schedule of stock option activity

The following table presents a summary of all stock option activity:


	Shares			Weighted- Average Exercise Price per Share		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2025		9,098,233		$	2.64		7.72	$	3,386
Granted		7,435,819			3.82
Exercised		(421,313	)		1.83
Canceled or forfeited		(424,184	)		2.18
Outstanding at June 30, 2026		15,688,555		$	3.23		8.36	$	378,796
Vested and expected to vest at June 30, 2026		15,688,555		$	3.23		8.36	$	378,796
Vested and exercisable at June 30, 2026		5,935,504		$	2.93		7.12	$	145,130

Schedule Of Stock-Based Compensation Expense

The following table presents the classification of stock-based compensation expense included in the Company’s condensed consolidated statements of operations and comprehensive loss (in thousands):


	Three Months Ended June 30,				Six Months Ended June 30,
	2026		2025		2026		2025
Research and development	$	719	$	192	$	1,188	$	404
General and administrative		2,915		631		3,750		1,271
Total	$	3,634	$	823	$	4,938	$	1,675

Condensed Consolidated Statements of Operations and Comprehensive Loss (unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Collaboration revenue	$ 148	$ 0	$ 148	$ 0
Operating expenses:
Research and development cost	39,377	30,126	77,130	64,031
General and administrative	11,657	6,394	21,357	12,730
Total operating expenses	51,034	36,520	98,487	76,761
Loss from operations	(50,886)	(36,520)	(98,339)	(76,761)
Other income (expense):
Interest income	4,189	1,049	6,618	2,306
Interest expense	(210)	(396)	(502)	(795)
Sublease income - related party	0	1,057	0	2,114
Change in fair value of simple agreement for future equity	(5,556)	0	(5,556)	0
Total other (expense) income, net	(1,577)	1,710	560	3,625
Net loss	(52,463)	(34,810)	(97,779)	(73,136)
Cumulative dividends on convertible preferred stock	(14,492)	(10,184)	(32,181)	(19,965)
Deemed dividend upon down-round of convertible preferred stock	0	0	(7,875)	0
Net loss allocable to common stockholders	$ (66,955)	$ (44,994)	$ (137,835)	$ (93,101)
Net loss per share allocable to common stockholders, basic	$ (2.32)	$ (22.28)	$ (8.86)	$ (46.13)
Net loss per share allocable to common stockholders, diluted	$ (2.32)	$ (22.28)	$ (8.86)	$ (46.13)
Weighted average common shares outstanding, basic	28,908,277	2,019,111	15,553,335	2,018,354
Weighted average common shares outstanding, diluted	28,908,277	2,019,111	15,553,335	2,018,354
Comprehensive loss:
Net loss	$ (52,463)	$ (34,810)	$ (97,779)	$ (73,136)
Change in unrealized gains (losses) on marketable securities	(18)	(5)	(18)	(21)
Comprehensive loss	$ (52,481)	$ (34,815)	$ (97,797)	$ (73,157)

Property and Equipment, Net (Additional Information) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025	Dec. 31, 2025
Property, Plant, and Equipment [Abstract]
Finance lease right-of-use assets	$ 2.9		$ 2.9		$ 2.9
Accumulated amortization expense	0.9		0.9		$ 0.7
Depreciation and amortization expense	$ 0.6	$ 0.2	1.2	$ 1.3
Finance lease right-of-use asset amortization			$ 0.3	$ 0.3

Net Loss Per Share (Additional Information) (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Earnings Per Share [Abstract]
Incremental Common Shares Attributable to Dilutive Effect of Contingently Issuable Shares	419,506	419,506	419,506	419,506

Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of contingently issuable shares. Contingently issuable shares are those shares that are issuable for little or no cash contingent on certain conditions being met.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482662/260-10-50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 23
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482689/260-10-45-23

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 26
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482689/260-10-45-26

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 44
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482689/260-10-45-44

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 51
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482689/260-10-45-51

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 52
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482689/260-10-45-52

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 53
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482689/260-10-45-53

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
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-Name Accounting Standards Codification
-Section 45
-Paragraph 54
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482689/260-10-45-54

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 48
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482689/260-10-45-48

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 48
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482689/260-10-45-48

Other Liabilities Disclosure [Abstract]

Accrued Expenses and Other Current Liabilities

6 Months Ended

Jun. 30, 2026

Accrued Expenses and Other Current Liabilities

5. Accrued Expenses and Other Current Liabilities

The following table summarizes accrued expenses and other current liabilities (in thousands):


	June 30,		December 31,
	2026		2025
Accrued employee compensation and benefits	$	5,459	$	9,079
Accrued research and development expenses		8,888		8,334
Accrued offering costs		1,399		491
Other		4,226		726
Total	$	19,972	$	18,630

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Jun. 30, 2026
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Net Loss Per Share - Schedule of Calculation of Diluted Net Loss Per Share Allocable to Common Stockholders (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	15,269,049	48,041,668	15,269,049	48,041,668
Series A Preferred Stock
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0	1,002,805	0	1,002,805
Series B Preferred Stock
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0	4,069,102	0	4,069,102
Series C Preferred Stock
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0	6,540,022	0	6,540,022
Series D Preferred Stock
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0	12,669,755	0	12,669,755
Series E Preferred Stock
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0	15,128,745	0	15,128,745
Common Stock Warrants
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0	24,152	0	24,152
Outstanding stock options
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	15,269,049	8,607,087	15,269,049	8,607,087

Term Loan

6 Months Ended

Jun. 30, 2026

Debt Disclosure [Abstract]

Term Loan

9. Term Loan

On September 21, 2021, the Company entered into a Loan and Security Agreement with Silicon Valley Bank (the “Lender”), which was subsequently amended (the “Loan Agreement”), which provided for aggregate term loans of $15.0 million. In connection with the Loan Agreement, the Company also issued common stock warrants to the Lender (refer to Note 7, Stockholders’ Equity (Deficit)).

On November 22, 2024, the Company and the Lender executed an amendment to the Loan Agreement under which the Lender extended the term loan amortization date to April 1, 2025 and added two interest-only extension events that could further extend the term loan amortization date. The amendment also required the Company to maintain the lesser of $60.0 million or 50% of the Company’s consolidated cash within the Company’s primary operating account with the Lender. The amendment was accounted for as a debt modification, rather than an extinguishment, as the difference in the present value of the cash flows under the terms of the original debt agreement and the terms immediately after the amendment was less than 10%. As a result, issuance costs paid to the Lender in connection with the amendment, which were not significant, were recorded as a reduction of the carrying amount of the debt liability. Unamortized issuance costs as of the date of the modification are amortized to interest expense using the effective interest method through the loan maturity date.

Term loan balances, including final payments, are summarized as follows (in thousands):


	June 30,			December 31,
	2026			2025
Total term loan principal	$	5,000		$	12,500
Final payments		726			647
Unamortized debt discount and issuance costs		(16	)		(70	)
Term loan, net of discount	$	5,710		$	13,077

The term loan matures on October 1, 2026. After triggering an interest-only extension upon the issuance of the Series E Preferred Stock in January 2025, which extended the interest-only period on the term loan, the Company began paying principal in 12 equal monthly payments of approximately $1.3 million each on November 1, 2025. The term loan bears interest at a floating rate equal to the greater of (i) 6.75% and (ii) the prime rate plus a margin; provided that the interest rate will not exceed 6.75%. The term loan calls for an additional final payment equal to 4.5% of the aggregate principal amount borrowed, as well as a fee of approximately $0.1 million, due upon (a) the term loan maturity date, (b) the repayment of the term loan in full, (c) as required pursuant to permitted prepayment or mandatory prepayment upon an acceleration, or (d) the termination of the Loan Agreement. The Company may, at its option, prepay the term loan in full or in part at any time prior to maturity, subject to a prepayment fee ranging between 0% and 3% of the outstanding principal amount of the term loan. The prepayment fee would also be due and payable in the event of an acceleration of the principal amount of the loan due to an event of default. The Loan Agreement contains affirmative covenants and certain restrictive covenants. The Company was in compliance with all financial and nonfinancial covenants as of June 30, 2026.

In addition, the Company is accreting the final payments over the term of the Loan Agreement as interest expense using the effective interest method. As of June 30, 2026 and December 31, 2025, the Company accreted a cumulative final payment of $0.7 million and $0.6 million, respectively, which is presented within term loan, net of discount on its condensed consolidated balance sheets.

For the six months ended June 30, 2026 and 2025, the effective interest rate of the term loan was 8.8% and 8.9%, respectively.

The term loan includes an embedded derivative related to the payment of interest upon an event of default. The Company determined the estimated fair value of the embedded derivative was not material to the condensed consolidated financial statements. Additionally, the term loan includes contingent payment features which also represent an embedded derivative which requires bifurcation from the debt host. As of June 30, 2026 and December 31, 2025, the Company determined the estimated fair value of the contingent payment features embedded derivative was not material to the condensed consolidated financial statements. The Company will reassess the probability of these contingent payment events and the estimated fair value of the related embedded derivatives at

each reporting period and revise the estimated fair value of the derivative in the Company’s condensed consolidated financial statements.

Stockholders' Equity (Deficit) - Schedule of Reserved Shares of Common Stock for the Conversion or Exercise (Details) - shares	Jun. 30, 2026	Dec. 31, 2025
Class of Stock [Line Items]
Common Stock Shares, Reserved	27,693,665	49,630,332
Series A Preferred Stock
Class of Stock [Line Items]
Common Stock Shares, Reserved	0	1,002,805
Series B Preferred Stock
Class of Stock [Line Items]
Common Stock Shares, Reserved	0	4,069,102
Series C Preferred Stock
Class of Stock [Line Items]
Common Stock Shares, Reserved	0	6,540,022
Series D Preferred Stock
Class of Stock [Line Items]
Common Stock Shares, Reserved	0	12,669,755
Series E Preferred Stock
Class of Stock [Line Items]
Common Stock Shares, Reserved	0	15,128,745
Common Stock Warrants
Class of Stock [Line Items]
Common Stock Shares, Reserved	0	24,152
Outstanding stock options
Class of Stock [Line Items]
Common Stock Shares, Reserved	15,688,555	9,098,233
Unissued stock-based awards under the 2016 Employee, Director and Consultant Equity Incentive Plan
Class of Stock [Line Items]
Common Stock Shares, Reserved	0	1,097,518
Unissued stock-based awards under the 2026 Stock Option and Incentive Plan
Class of Stock [Line Items]
Common Stock Shares, Reserved	10,895,110	0
Unissued stock-based awards under the 2026 Employee Stock Purchase Plan
Class of Stock [Line Items]
Common Stock Shares, Reserved	1,110,000	0

Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2026

Fair Value Disclosures [Abstract]

Schedule of Financial Assets Measured at Fair Value on a Recurring Basis and Indicate the Level of the Fair Value Hierarchy


	Fair Value Measurements as of June 30, 2026:
	Level 1		Level 2		Level 3		Total
Assets
Cash equivalents:
Money market funds	$	1,075,747	$	—	$	—	$	1,075,747
U.S. Treasury bills		—		9,999		—		9,999
Marketable securities:
U.S. Treasury bills		—		33,637		—		33,637
Total assets	$	1,075,747	$	43,636	$	—	$	1,119,383


	Fair Value Measurements as of December 31, 2025:
	Level 1		Level 2		Level 3		Total
Assets
Cash equivalents:
Money market funds	$	27,133	$	—	$	—	$	27,133
Total assets	$	27,133	$	—	$	—	$	27,133

Schedule of Gross Unrealized Gains and Losses of Marketable Securities

The following table summarizes the gross unrealized gains and losses of the Company’s marketable securities (in thousands):


	June 30, 2026
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Marketable securities:
U.S. Treasury bills	$	33,655	$	—	$	(18	)	$	33,637

As of June 30, 2026, all of the Company’s marketable securities had remaining contractual maturities of less than one year.

Schedule of Changes in the Aggregate Fair Value

The following table presents changes in the aggregate fair value of the Company’s Series E preferred stock tranche right liability (in thousands):


	Amount
Balance as of December 31, 2024	$	2,167
Settlement of Series E preferred stock tranche right liability		(2,167	)
Balance as of June 30, 2025	$	—

The following table presents changes in the aggregate fair value of the SAFE (in thousands):


	Amount
Balance as of December 31, 2025	$	—
Fair value of SAFE at issuance		50,000
Change in fair value of SAFE		5,556
Conversion of SAFE into common stock		(55,556	)
Balance as of June 30, 2026	$	—

Stockholders' Equity (Deficit) (Tables)

6 Months Ended

Jun. 30, 2026

Equity [Abstract]

Schedule of Reserved Shares of Common Stock for the Conversion or Exercise

The Company has reserved shares of common stock for the conversion or exercise of the following securities:


	June 30,		December 31,
	2026		2025
Series A Preferred Stock		—		1,002,805
Series B Preferred Stock		—		4,069,102
Series C Preferred Stock		—		6,540,022
Series D Preferred Stock		—		12,669,755
Series E Preferred Stock		—		15,128,745
Common stock warrants		—		24,152
Outstanding stock options		15,688,555		9,098,233
Unissued stock-based awards under the 2016 Employee, Director and Consultant Equity Incentive Plan		—		1,097,518
Unissued stock-based awards under the 2026 Stock Option and Incentive Plan		10,895,110		—
Unissued stock-based awards under the 2026 Employee Stock Purchase Plan		1,110,000		—
Total		27,693,665		49,630,332

Simple Agreement for Future Equity (Additional Information) (Details) - USD ($) $ / shares in Units, $ in Thousands		6 Months Ended
	Mar. 27, 2026	Jun. 30, 2026	Jun. 30, 2025
Class of Stock [Line Items]
Conversion of Stock, Amount Converted		$ 814,540	$ 0
Common Stock, Conversion Basis	The SAFE was automatically convertible into the number of shares of common stock obtained by dividing (i) $50.0 million by (ii) the IPO Discount Price upon the closing of an IPO.
Converted shares		2,777,777
Simple Agreement for Future Equity [Member]
Class of Stock [Line Items]
Gross Proceeds	$ 50,000
Fair Value of Agreement	50,000
Simple Agreement for Future Equity [Member] \| Common Stock [Member]
Class of Stock [Line Items]
Fair Value of Agreement Upon Conversion	55,600
Simple Agreement for Future Equity [Member] \| IPO [Member]
Class of Stock [Line Items]
Conversion of Stock, Amount Converted	$ 50,000
Equity Agreement Description	if the IPO Price was greater than or equal to $9.4864 per share, and (ii) the Initial IPO Discount Price was equal to or less than $9.4864 per share, then the IPO Discount Price would have equaled $9.4864 per share; and provided further that if the IPO Price was less than $9.4864, the IPO Discount Price would have equaled the IPO Price
Equity Conversion Rate	90.00%
Price Per Share	$ 9.4864
Discount Price Per Share	$ 18
Simple Agreement for Future Equity [Member] \| IPO [Member] \| Common Stock [Member]
Class of Stock [Line Items]
Converted shares	2,777,777

Document and Entity Information - shares	6 Months Ended
Document and Entity Information - shares	Jun. 30, 2026	Aug. 10, 2026
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Jun. 30, 2026
Document Fiscal Year Focus	2026
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--12-31
Securities Act File Number	001-43331
Entity Registrant Name	Parabilis Medicines, Inc.
Entity Central Index Key	0001657677
Entity Current Reporting Status	No
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	PBLS
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	47-4505725
Entity Address, Address Line One	30 Acorn Park Drive
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02140
City Area Code	617
Local Phone Number	945-9510
Voting Common Stock [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		121,952,030
Nonvoting Common Stock [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		1,581,210

Nature of the Business and Basis of Presentation (Additional Information) (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended	3 Months Ended			6 Months Ended
	Jun. 03, 2026	Jun. 30, 2026	Jun. 30, 2026	Mar. 31, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025	Dec. 31, 2025
Class of Stock [Line Items]
Incorporation date						Jul. 10, 2015
Reverse stock split	1-for-1.5389
Issuance of common stock upon exercise of stock options shares						421,313
Proceeds from Issuance of Common Stock		$ 712,900
Gross proceeds		50,000
Proceeds From Issuance Of Long Term Debt		15,000
Proceeds from Issuance of Convertible Preferred Stock		811,800
Payments of Stock Issuance Costs						$ 680	$ 62
Commissions and offering costs		57,600
Accumulated deficit		(639,283)	$ (639,283)			(639,283)		$ (541,504)
Proceeds from concurrent private placement of common stock		787,900				$ 83,333	$ 0
Share Price Per Share, Percentage						90.00%
License and Collaboration Agreement with Regeneron [Member]
Class of Stock [Line Items]
Stock Issued During Period, Shares, New Issues						4,166,666
Proceeds from Issuance of Common Stock		75,000				$ 75,000
Upfront Payment		$ 50,000				$ 50,000
Sale of stock price per share		$ 18	$ 18			$ 18
Share Price Per Share, Percentage						90.00%
Common Stock [Member]
Class of Stock [Line Items]
Stock Issued During Period, Shares, New Issues		5,025,000
Issuance of common stock upon exercise of stock options shares		5,025,000	328,614	92,699	5,791
Number of share issued and sold		4,166,666
Payments of Stock Issuance Costs		$ 57,600
Sale of stock price per share		$ 18	$ 18			$ 18
Common Stock [Member] \| IPO [Member]
Class of Stock [Line Items]
Stock Issued During Period, Shares, New Issues		38,525,000
Sale of stock price per share		$ 20	$ 20			$ 20

Fair Value Measurements (Additional Information) (Details) - USD ($) $ / shares in Units, $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2026	Dec. 31, 2024
Net asset value per share	$ 1
Unrealized loss on aggregate fair value	$ 33.6
convertible preferred stock per share		$ 6.43
Contractual Purchase Price		$ 6.23
Fair Value Proceeds Received	$ 50.0
Converted shares	2,777,777
Discount Price	$ 18
Common stock issued upon conversion	$ 55.6

Net asset value per share or per unit of investments in certain entities that calculate net asset value per share. Includes, but is not limited to, by unit, membership interest, or other ownership interest. Investment includes, but is not limited to, investment in certain hedge funds, venture capital funds, private equity funds, real estate partnerships or funds. Excludes fair value disclosure.