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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

FORM 10-Q

(Mark One)

☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the quarterly period ended March 31, 2026

☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from to

Commission File Number: 001-41740

Apogee Therapeutics, Inc.

(Exact name of registrant as specified in its charter)



Delaware	93-4958665
(State or other jurisdiction of incorporation or organization)	(I.R.S. Employer Identification Number)

221 Crescent St., Building 17, Suite 102b

Waltham, MA 02453

(650) 394‑5230

(Address including zip code, and telephone number including area code, of registrant’s principal executive offices)

Former name, former address and former fiscal year, if changed since last report: N/A

Securities registered pursuant to Section 12(b) of the Exchange Act:


Title of each class	Trading Symbol(s)	Name of each exchange on which registered
Common Stock, par value $0.00001 per share	APGE	The Nasdaq Global Market

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ☒ No ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§ 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes ☒ No ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b‑2 of the Exchange Act.


Large accelerated filer	☒	Accelerated filer	☐
Non-accelerated filer	☐	Smaller reporting company	☐
		Emerging growth company	☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b‑2 of the Exchange Act). Yes ☐ No ☒

As of May 4, 2026, the registrant had 75,389,375 shares of common stock, $0.00001 par value per share, outstanding, comprising 61,902,733 shares of voting common stock, $0.00001 par value per share, and 13,486,642 shares of non-voting common stock, $0.00001 par value per share.

Table of Contents

APOGEE THERAPEUTICS, INC.

TABLE OF CONTENTS



		Page
PART I	FINANCIAL INFORMATION	1
Item 1.	Condensed Consolidated Financial Statements (Unaudited)	1
	Condensed Consolidated Balance Sheets as of March 31, 2026 and December 31, 2025	1
	Condensed Consolidated Statement of Operations for the Three Months Ended March 31, 2026 and 2025	2
	Condensed Consolidated Statement of Comprehensive Loss for the Three Months Ended March 31, 2026 and 2025	3
	Condensed Consolidated Statement of Stockholders’ Equity for the Three Months Ended March 31, 2026 and 2025	4
	Condensed Consolidated Statement of Cash Flows for the Three Months Ended March 31, 2026 and 2025	6
	Notes to the Unaudited Interim Condensed Consolidated Financial Statements	7
Item 2.	Management’s Discussion and Analysis of Financial Condition and Results of Operations	24
Item 3.	Quantitative and Qualitative Disclosures About Market Risk	37
Item 4.	Controls and Procedures	37
PART II	OTHER INFORMATION	38
Item 1.	Legal Proceedings	38
Item 1A.	Risk Factors	38
Item 2.	Unregistered Sales of Equity Securities and Use of Proceeds	69
Item 3.	Defaults Upon Senior Securities	70
Item 4.	Mine Safety Disclosures	70
Item 5.	Other Information	70
Item 6.	Exhibits	71
	Signatures	72

Table of Contents

SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

This Quarterly Report on Form 10-Q (this “Quarterly Report”) contains “forward-looking statements” within the meaning of the federal securities laws, which statements are subject to substantial risks and uncertainties and are based on current expectations, estimates, forecasts and assumptions. All statements other than statements of historical fact included in this Quarterly Report, including statements concerning our plans, objectives, goals, strategies, future events, future revenues or performance, capital requirements or financing needs, capital expenditures, commitments, preclinical studies, clinical trials, plans or intentions relating to product candidates, expected markets and business trends, and other statements, including without limitation, those discussed under the sections titled “Risk Factors” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations”, are forward-looking statements. In some cases, you can identify forward-looking statements by terms such as “may,” “might,” “will,” “would,” “shall,” “objective,” “intend,” “target,” “should,” “could,” “can,” “expect,” “anticipate,” “believe,” “design,” “estimate,” “forecast,” “predict,” “potential,” “plan,” “seek,” or “continue” or the negative of these terms and similar expressions intended to identify forward-looking statements. Forward-looking statements reflect our current views with respect to future events. Given the significant risks and uncertainties, you should not place undue reliance on these forward-looking statements.

There are a number of risks, uncertainties and other factors that could cause our actual results to differ materially from the forward-looking statements expressed or implied in this Quarterly Report. Such risks, uncertainties and other factors include, among others, the following:

•

our plans to develop and commercialize our programs for the treatment of atopic dermatitis, asthma, eosinophilic esophagitis, chronic obstructive pulmonary disease, and related inflammatory and immunology indications with high unmet need;

•

our ability to obtain funding for our operations, including funding necessary to complete the development and potential commercialization of our programs;

•

the timing and focus of our ongoing and future preclinical studies and clinical trials and the reporting of data from those studies and trials;

•

the beneficial characteristics, safety, efficacy and therapeutic effects of our programs;

•

our plans relating to the further development of our programs, including additional indications we may pursue;

•

the size of the market opportunity for our programs, including our estimates of the number of patients who suffer from the diseases we are targeting;

•

our continued reliance on third parties to conduct additional preclinical studies and clinical trials of our programs and for the manufacture of our product candidates for preclinical studies and clinical trials;

•

the success, cost and timing of our preclinical and clinical development activities and planned clinical trials;

•

the continuation of our existing collaborations and licensing and other arrangements and entry into new collaborations and licensing and other arrangements that may be necessary or desirable to develop, manufacture or commercialize our product candidates;

•

the timing of and our ability to obtain and maintain regulatory approvals for our programs, as well as potential future programs;

•

the rate and degree of market acceptance of our programs;

•

the success of competing treatments that are or may become available;

•

our ability to attract and retain key management and technical personnel;

•

our expectations regarding our ability to obtain, maintain and enforce intellectual property protection for our programs;

•

our financial performance;

•

global macroeconomic conditions;

•

the period over which we estimate our existing cash and cash equivalents, marketable securities and long-term marketable securities will be sufficient to fund our future operating expenses and capital expenditure requirements; and

•

our anticipated use of our existing resources.

Table of Contents

These and other risks and uncertainties and other factors, including those discussed under the section titled “Risk Factors” of this Quarterly Report, may cause our actual results and outcomes, or timing of our results or outcomes, to differ materially and adversely from the forward-looking statements expressed or implied in this Quarterly Report, including factors disclosed in the sections titled “Risk Factors” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations.” You should evaluate all forward-looking statements made in this Quarterly Report in the context of these risks and uncertainties.

We caution you that the risks, uncertainties and other factors referred to above and elsewhere in this Quarterly Report may not contain all of the risks, uncertainties and other factors that may affect us, our future results or our operations. Moreover, new risks may emerge from time to time. It is not possible for us to predict all risks. In addition, we cannot assure you that we will realize the results, benefits or developments that we expect or anticipate or, even if substantially realized, that they will result in the consequences or affect us or our business in the way expected.

All forward-looking statements in this Quarterly Report apply only as of the date made and are expressly qualified in their entirety by this and other cautionary statements included in this Quarterly Report. Except as required by law, we undertake no obligation to publicly update or revise any forward-looking statements, whether as a result of new information, subsequent events, changes in assumptions or circumstances or otherwise.

In addition, statements such as “we believe” and similar statements reflect our beliefs and opinions on the relevant subject. These statements are based upon information available to us as of the date of this Quarterly Report, and while we believe we have a reasonable basis for such statements, our information may be limited or incomplete, and our statements should not be read to indicate that we have conducted an exhaustive inquiry into, or review of, all potentially available relevant information. These statements are inherently uncertain and you are cautioned not to unduly rely upon these statements.

The Apogee name and logo are our registered trademarks. This Quarterly Report contains references to our trademarks and to trademarks and service marks belonging to other entities. Solely for convenience, trademarks, service marks and trade names referred to in this Quarterly Report, including logos, artwork and other visual displays, may appear without the ®, SM, or ™ symbols, but such references are not intended to indicate in any way that we will not assert, to the fullest extent under applicable law, our rights or the rights of the applicable licensor to these trademarks and trade names. We do not intend our use or display of other entities’ trade names, trademarks or service marks to imply a relationship with, or endorsement or sponsorship of us by, any other entity.

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PART I – FINANCIAL INFORMATION

APOGEE THERAPEUTICS, INC.

CONDENSED CONSOLIDATED BALANCE SHEETS

(UNAUDITED)

(In thousands, except share data)


	MARCH 31, 2026			DECEMBER 31, 2025
Assets
Current assets:
Cash and cash equivalents	$	451,797		$	131,549
Marketable securities		608,088			598,643
Prepaid expenses and other current assets		13,912			11,166
Total current assets		1,073,797			741,358
Long-term marketable securities		198,354			172,730
Property and equipment, net		5,280			5,688
Right-of-use asset, net		7,707			8,687
Other non-current assets		8,516			8,671
Total assets	$	1,293,654		$	937,134
Liabilities and stockholders' equity
Current liabilities:
Accounts payable	$	1,237		$	1,221
Lease liability		3,138			3,504
Accrued expenses and other current liabilities		28,577			23,181
Total current liabilities		32,952			27,906
Long-term liabilities:
Lease liability, net of current		4,909			5,345
Total liabilities		37,861			33,251
Commitments and contingencies (Note 9)
Stockholders' equity:
Common Stock; $0.00001 par value, 400,000,000 authorized, 75,323,726 issued and 74,882,396 outstanding as of March 31, 2026; 400,000,000 authorized, 69,038,943 issued and 68,401,349 outstanding as of December 31, 2025		1			1
Additional paid-in capital		1,892,411			1,464,561
Accumulated other comprehensive income (loss)		(749	)		1,080
Accumulated deficit		(635,870	)		(561,759	)
Total stockholders’ equity		1,255,793			903,883
Total liabilities and stockholders’ equity	$	1,293,654		$	937,134

The accompanying notes are an integral part of these condensed consolidated financial statements.

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APOGEE THERAPEUTICS, INC.

CONDENSED CONSOLIDATED STATEMENT OF OPERATIONS

(UNAUDITED)

(In thousands, except share and per share data)


	THREE MONTHS ENDED MARCH 31,
	2026			2025
Operating expenses:
Research and development (1)	$	60,819		$	46,387
General and administrative		21,953			16,709
Total operating expenses		82,772			63,096
Loss from operations		(82,772	)		(63,096	)
Other income, net:
Interest income, net		8,740			7,840
Total other income, net		8,740			7,840
Net loss before taxes		(74,032	)		(55,256	)
Provision for income taxes		(79	)		(83	)
Net loss after taxes	$	(74,111	)	$	(55,339	)
Net loss per share, basic and diluted	$	(1.06	)	$	(0.95	)
Weighted-average common shares outstanding, basic and diluted		69,668,439			58,195,272

(1)

Includes related party amounts of $640 and $32 for the three months ended March 31, 2026 and 2025, respectively.

The accompanying notes are an integral part of these condensed consolidated financial statements.

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APOGEE THERAPEUTICS, INC.

CONDENSED CONSOLIDATED STATEMENT OF COMPREHENSIVE LOSS

(UNAUDITED)

(In thousands)


	THREE MONTHS ENDED MARCH 31,
	2026			2025
Net loss	$	(74,111	)	$	(55,339	)
Unrealized (loss) gain on marketable securities, net of tax		(1,829	)		159
Comprehensive loss	$	(75,940	)	$	(55,180	)

The accompanying notes are an integral part of these condensed consolidated financial statements.

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APOGEE THERAPEUTICS, INC.

CONDENSED CONSOLIDATED STATEMENT OF STOCKHOLDERS’ EQUITY

(UNAUDITED)

(In thousands, except share data)


	COMMON STOCK				ADDITIONAL PAID-IN CAPITAL		ACCUMULATED DEFICIT			ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)			TOTAL STOCKHOLDERS' EQUITY
	SHARES		AMOUNT		AMOUNT		AMOUNT			AMOUNT			AMOUNT
Balance at December 31, 2025		68,401,349	$	1	$	1,464,561	$	(561,759	)	$	1,080		$	903,883
Common stock issued, net of issuance costs of $25,059		5,750,000		—		377,441		—			—			377,441
Common stock issued, net of issuance costs of $769, under at the market equity offering program (“ATM Facility”)		369,220		—		28,934		—			—			28,934
Vesting of restricted stock		222,013		—		—		—			—			—
Issuance of common stock upon exercise of stock options		139,814		—		4,320		—			—			4,320
Equity-based compensation expense		—		—		17,155		—			—			17,155
Unrealized loss on marketable securities, net of tax		—		—		—		—			(1,829	)		(1,829	)
Net loss		—		—		—		(74,111	)		—			(74,111	)
Balance at March 31, 2026		74,882,396	$	1	$	1,892,411	$	(635,870	)	$	(749	)	$	1,255,793

The accompanying notes are an integral part of these condensed consolidated financial statements.

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APOGEE THERAPEUTICS, INC.

CONDENSED CONSOLIDATED STATEMENT OF STOCKHOLDERS’ EQUITY

(UNAUDITED)

(In thousands, except share data)


	COMMON STOCK				ADDITIONAL PAID-IN CAPITAL		ACCUMULATED DEFICIT			ACCUMULATED OTHER COMPREHENSIVE INCOME		TOTAL STOCKHOLDERS' EQUITY
	SHARES		AMOUNT		AMOUNT		AMOUNT			AMOUNT		AMOUNT
Balance at December 31, 2024		58,062,898	$	1	$	1,021,794	$	(305,916	)	$	915	$	716,794
Vesting of restricted stock		213,104		—		—		—			—		—
Issuance of common stock upon exercise of stock options		28,799		—		622		—			—		622
Equity-based compensation expense		—		—		11,126		—			—		11,126
Unrealized gain on marketable securities, net of tax		—		—		—		—			159		159
Net loss		—		—		—		(55,339	)		—		(55,339	)
Balance at March 31, 2025		58,304,801	$	1	$	1,033,542	$	(361,255	)	$	1,074	$	673,362

The accompanying notes are an integral part of these condensed consolidated financial statements.

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APOGEE THERAPEUTICS, INC.

CONDENSED CONSOLIDATED STATEMENT OF CASH FLOWS

(UNAUDITED)

(In thousands)


	THREE MONTHS ENDED MARCH 31,
	2026			2025
Cash flows from operating activities:
Net loss	$	(74,111	)	$	(55,339	)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation expense		408			207
Equity-based compensation expense		17,155			11,126
Amortization of discounts on marketable securities		(1,549	)		(2,379	)
Non-cash lease expense		980			857
Changes in operating assets and liabilities:
Prepaid expenses and other current assets		(2,490	)		895
Other non-current assets		155			(6,841	)
Accounts payable		16			1,374
Operating lease liability		(802	)		(1,014	)
Accrued expenses		4,668			2,637
Net cash used in operating activities		(55,570	)		(48,477	)
Cash flows from investing activities:
Purchases of marketable securities		(183,244	)		(98,201	)
Maturities of marketable securities		147,895			115,500
Purchases of property and equipment		—			(4,317	)
Net cash (used in) provided by investing activities		(35,349	)		12,982
Cash flows from financing activities:
Proceeds from issuance of common stock, net of issuance costs		378,169			—
Proceeds from issuance of common stock under the ATM Facility, net of issuance costs		28,934			—
Proceeds from exercise of options		4,064			622
Net cash provided by financing activities		411,167			622
Increase (decrease) in cash, cash equivalents and restricted cash		320,248			(34,873	)
Cash, cash equivalents and restricted cash, beginning of period		131,549			142,083
Cash, cash equivalents and restricted cash, end of period	$	451,797		$	107,210
Supplemental disclosures of non-cash activities:
Operating lease right-of-use asset obtained in exchange for operating lease liability	$	—		$	999
Property and equipment in accounts payable	$	—		$	229
Unpaid financing cost in accrued liability	$	728		$	37
Issuance of common stock upon exercise of stock options for which proceeds had not yet been received	$	256		$	—
Reconciliation of cash, cash equivalents and restricted cash:
Cash and cash equivalents	$	451,797		$	106,916
Restricted cash		—			294
Total	$	451,797		$	107,210

The accompanying notes are an integral part of these condensed consolidated financial statements.

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APOGEE THERAPEUTICS, INC.

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(UNAUDITED)

Nature of the Business

Apogee Therapeutics, Inc., together with its consolidated subsidiary (collectively, “Apogee” or the “Company”), is a clinical stage biotechnology company advancing optimized, novel biologics with the potential for differentiated efficacy and dosing in the largest inflammatory and immunology (“I&I”) markets, including for the treatment of atopic dermatitis (“AD”), asthma, eosinophilic esophagitis (“EoE”), chronic obstructive pulmonary disease (“COPD”), and other I&I indications. Apogee's antibody programs are designed to overcome limitations of existing therapies by targeting well-established mechanisms of action and incorporating advanced antibody engineering to optimize half-life and other properties.

The Company is subject to risks and uncertainties common to early stage companies in the biotechnology industry, including, but not limited to, completing preclinical studies and clinical trials, obtaining regulatory approval for its programs, market acceptance of products, development by competitors of new technological innovations, dependence on key personnel, the ability to attract and retain qualified employees, reliance on third-party organizations, protection of proprietary technology, compliance with government regulations, and the ability to raise additional capital to fund operations. The Company’s programs currently under development, zumilokibart (APG777), APG279 (zumilokibart + APG990), APG273 (zumilokibart + APG333), and APG808, will require significant additional research and development efforts, including extensive preclinical and clinical testing and regulatory approval prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel and infrastructure, and extensive compliance reporting capabilities. Even if the Company’s development efforts are successful, it is uncertain when, if ever, the Company will realize revenue from product sales. The Company has primarily funded its operations with proceeds from the sales of preferred units and common stock and has not generated any revenue since inception.

As a result, the Company will need substantial additional funding to support its continued operations and growth strategy. Until such a time as the Company can generate significant revenue from product sales, if ever, the Company expects to finance its operations through the sale of equity, debt financings or other capital sources, including collaborations with other companies or other strategic transactions. The Company may be unable to raise additional funds or enter into such other agreements on favorable terms, or at all. If the Company fails to raise capital or enter into such agreements as, and when, needed, the Company may have to significantly delay, scale back or discontinue the development and commercialization of one or more of its programs.

Company Liquidity

The Company has evaluated whether there are conditions and events, considered in the aggregate, that raise substantial doubt about its ability to continue as a going concern within one year after the date that the accompanying consolidated financial statements are issued. The Company had an accumulated deficit of $635.9 million as of March 31, 2026. Further, the Company incurred a net loss of $74.1 million and experienced negative cash flows from operations of $55.6 million for the three months ended March 31, 2026. Based on the Company’s current operating plan, it estimates that its existing cash and cash equivalents of $451.8 million, marketable securities of $608.1 million and long-term marketable securities of $198.4 million as of March 31, 2026, will be sufficient to enable the Company to fund its operating expenses and capital requirements through at least the next 12 months from the issuance of these consolidated financial statements.

The Company is subject to those risks associated with any biotechnology company that has substantial expenditures for research and development. There can be no assurance that the Company’s research and development projects will be successful, that products developed will obtain necessary regulatory approval, or that any approved product will be commercially viable. In addition, the Company operates in an environment of rapid technological change and is largely dependent on the services of its employees and consultants. If the Company fails to become profitable or is unable to sustain profitability on a continuing basis, then it may be unable to continue its operations at planned levels and be forced to reduce its operations.

This Quarterly Report contains references to the Company’s programs, which are used interchangeably to refer to the Company’s clinical programs within its pipeline and its products under development.

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Summary of Significant Accounting Policies

There have been no material changes to the significant accounting policies as disclosed in Note 2 to the consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2025.

Basis of Presentation

The condensed consolidated financial statements include the accounts of Apogee Therapeutics, Inc. and its wholly-owned subsidiary, Apogee Therapeutics Securities Corporation, formed as a Massachusetts security corporation in September 2024.

These condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). 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”). In the Company’s management opinion, the information furnished in these unaudited condensed consolidated financial statements reflects all adjustments, all of which are of a normal and recurring nature, necessary for a fair presentation of the financial position and results of operations for the interim reported periods. The Company considers events or transactions that occur after the balance sheet date but before the financial statements are issued to provide additional evidence relative to certain estimates or to identify matters that require additional disclosure. The results of operations for interim periods are not necessarily indicative of results to be expected for the full year or any other interim period.

Principles of Consolidation

The accompanying consolidated financial statements include the accounts of Apogee Therapeutics, Inc. and its wholly-owned subsidiary. All intercompany balances and transactions have been eliminated in consolidation.

Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts in the financial statements and accompanying notes. Actual results could materially differ from those estimates. Management considers many factors in selecting appropriate financial accounting policies and controls, and in developing the estimates and assumptions that are used in the preparation of these financial statements. Management must apply significant judgment in this process. In addition, other factors may affect estimates, including: expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates, and whether historical trends are expected to be representative of future trends. The estimation process often may yield a range of potentially reasonable estimates of the ultimate future outcomes and management must select an amount that falls within that range of reasonable estimates. Significant estimates relied upon in preparing the accompanying consolidated financial statements include, among others: research and development expenses and related prepaid or accrued costs, the valuation of equity-based compensation awards and related expense.

Segments

The Company has one operating segment and one reporting unit. The Company’s chief operating decision maker, its Chief Executive Officer, manages the Company’s operations on a consolidated basis for the purposes of assessing performance and allocating resources. All of the Company’s assets are located in the United States.

Fair Value of Financial Instruments

The Company is required to disclose information on all assets and liabilities reported at fair value that enables an assessment of the inputs used in determining the reported fair values. FASB ASC Topic 820, Fair Value Measurements and Disclosures (“ASC 820”), establishes a hierarchy of inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that the observable inputs be used when available. Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about the inputs that market participants would use in pricing the asset or liability and are developed based on the best information available in the circumstances. The fair value hierarchy applies only to the valuation inputs used in determining the reported fair value of the investments and is not a measure of the investment credit quality. The three levels of the fair value hierarchy are described below:

Level 1—Valuations based on quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date.

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Level 2—Valuations based on quoted prices for similar assets or liabilities in markets that are not active or for which all significant inputs are observable, either directly or indirectly.

Level 3—Valuations that require inputs that reflect the Company’s own assumptions that are both significant to the fair value measurement and unobservable.

To the extent that valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement.

Items measured at fair value on a recurring basis as of March 31, 2026 include cash equivalents and marketable securities (Notes 3 and 4). The carrying amounts reflected in the accompanying consolidated balance sheets for prepaid expenses and other current assets, accounts payable and accrued expenses approximate their fair values due to their short-term nature.

Property and Equipment, net

Property and equipment are recorded at cost. Depreciation is calculated using the straight-line method over the following estimated useful lives of the assets:


		ESTIMATED USEFUL LIFE
Furniture and fixtures		5 years
Lab equipment		5 years
IT equipment		3 years
Leasehold improvements		Shorter of the lease term or useful life

Upon disposal, retirement or sale, the cost of assets disposed of and the related accumulated depreciation are removed from the accounts and any resulting gain or loss is included in the results of operations. Expenditures for repairs and maintenance that do not improve or extend the lives of the respective assets are charged to expense as incurred.

Research and Development Expense

Research and development costs are expensed as incurred. Research and development expenses consist of costs incurred in performing research and development activities, including salaries and bonuses, overhead costs, contract services and other related costs. The value of goods and services received from contract research organizations and contract manufacturing organizations in the reporting period are estimated based on the level of services performed, and progress in the period in cases when the Company has not received an invoice from the supplier. In circumstances where amounts have been paid in excess of costs incurred, the Company records a prepaid expense. When billing terms under these contracts do not coincide with the timing of when the work is performed, the Company is required to make estimates of outstanding obligations to those third parties as of period end. Any accrual estimates are based on a number of factors, including the Company’s knowledge of the progress towards completion of the specific tasks to be performed, invoicing to date under the contracts, communication from the vendors of any actual costs incurred during the period that have not yet been invoiced and the costs included in the contracts. Significant judgments and estimates may be made in determining the accrued balances at the end of any reporting period. Actual results could differ from the estimates made by the Company.

Income Taxes

Income taxes are recorded in accordance with FASB ASC Topic 740, Income Taxes (“ASC 740”), which provides for deferred taxes using an asset and liability approach. The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements or tax returns. Deferred tax assets and liabilities are determined based on the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse.

Valuation allowances are provided if, based upon the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. In making such a determination, management considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies, and results of recent operations. If management determines that the Company would be able to realize its deferred tax assets in the future

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in excess of their net recorded amount, management would make an adjustment to the deferred tax asset valuation allowance, which would reduce the provision for income taxes.

The Company accounts for uncertain tax positions in accordance with the provisions of ASC 740. When uncertain tax positions exist, the Company recognizes the tax benefit to the extent that the position is more likely than not to be sustained on examination by the taxing authorities based on the technical merits of the position as well as consideration of the available facts and circumstances. The Company records interest and penalties related to uncertain tax positions, if applicable, as a component of income tax expense.

Cash and Cash Equivalents

The Company considers all highly liquid investments purchased with original final maturities of three months or less from the date of purchase to be cash equivalents. Cash and cash equivalents include cash held in banks and amounts held in interest-bearing money market funds, U.S. treasury securities, U.S. Government agency securities, and commercial paper.

Marketable Securities

The Company’s investments are comprised of U.S. government agency securities, U.S. treasury securities, commercial paper and corporate debt securities. Investments are classified at the time of purchase, based on management’s intent, as held-to-maturity, available-for-sale, or trading. All of the Company’s marketable security investments are classified as available-for-sale securities and are reported at fair market value using quoted prices in active markets for similar securities. The cost of securities sold is determined on a specific identification basis, and realized gains and losses are included as a component of other income within the condensed consolidated statements of operations and comprehensive loss. Unrealized gains and losses are included within the condensed consolidated statements of comprehensive loss.

The Company assesses its available-for-sale securities under the available-for-sale security impairment model in ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Statements as of each reporting date in order to determine if a portion of any decline in fair value below carrying value is the result of a credit loss for its available-for-sale securities. The Company records credit losses for its available-for-sale securities in the condensed consolidated statements of operations and comprehensive loss as credit loss expense, which is limited to the difference between the fair value and the amortized cost of the security. To date, the Company has not recorded any credit losses on its available-for-sale securities. Declines in fair value below carrying value attributable to non-credit related factors are recorded as accumulated other comprehensive loss, which is a separate component of stockholders’ equity.

The Company classifies its available-for-sale securities that mature within one year from the balance sheet date as current assets on the condensed consolidated balance sheets. Available-for-sale securities that mature more than one year from the balance sheet date are classified as non-current assets on the condensed consolidated balance sheets.

Leases

The Company determines the initial classification and measurement of its right-of-use assets and lease liabilities at the lease commencement date and thereafter if modified. The lease term includes any renewal options and termination options that the Company is reasonably assured to exercise. The present value of lease payments is determined by using the interest rate implicit in the lease, if that rate is readily determinable; otherwise, the Company uses its incremental borrowing rate. The incremental borrowing rate is determined by using the rate of interest that the Company would pay to borrow on a collateralized basis an amount equal to the lease payments for a similar term and in a similar economic environment.

Fixed lease expense for operating leases is recognized on a straight-line basis, unless the right-of-use assets have been impaired, over the reasonably assured lease term based on the total lease payments and is included in operating expenses in the statements of operations and comprehensive loss.

Pre-funded Warrants

The Company evaluates pre-funded warrants under FASB ASC Topic 480, Distinguishing Liabilities from Equity and FASB ASC Topic 815, Derivatives and Hedging (“ASC 815”) to determine whether the warrants should be classified as liabilities or equity. Pre-funded warrants are classified as stockholders’ equity when they are (i) indexed to the Company’s own stock and (ii) meet all equity‑classification conditions in ASC 815‑40. Proceeds received upon issuance of pre-funded warrants are recorded to additional paid‑in capital. Upon exercise, the Company records proceeds to common stock and additional paid‑in capital. Because the exercise

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price is nominal, equity‑classified pre‑funded warrants are included in basic and diluted weighted‑average shares outstanding beginning on the issuance date but are not reflected as legally outstanding shares until exercised.

Equity-Based Compensation

The Company issues equity-based awards to employees, managers, executives, non-employees and service providers in the form of restricted common stock, restricted stock units, and stock options. The Company accounts for equity-based compensation awards in accordance with FASB ASC Topic 718, Compensation-Stock Compensation.

The fair value of the Company’s common stock underlying its equity awards is based on the quoted market price of the Company’s common stock on the grant date. The Company estimates the fair value of its stock options using the Black-Scholes option pricing model, which uses as inputs the fair value of the Company’s common stock, and certain management estimates, including the expected stock price volatility, the expected term of the award, the risk-free rate, and expected dividends. Expected volatility is estimated using a combination of the Company’s historical stock price volatility and historical volatility data from a representative group of comparable publicly traded companies. The Company computes historical volatility using daily closing prices over a period that approximates the expected term of the equity-based awards. The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant commensurate with the expected term assumption. The Company uses the simplified method, under which the expected term is presumed to be the midpoint between the vesting date and the end of the contractual term. The Company utilizes this method due to lack of historical exercise data. The expected dividend yield is assumed to be zero as the Company has no current plans to pay any dividends on common stock. The fair value of the restricted stock units are based on the Company’s stock price on the date of the grant.

The Company generally issues equity awards that are subject to either service-based vesting conditions and in limited instances, service-based and performance-based vesting conditions. Compensation expense for awards issued to grantees with service-based vesting conditions are recognized on a straight-line basis based on the grant date fair value over the associated requisite service period of the award, which is generally the vesting term. Compensation expense for awards to grantees with service-based and performance-based vesting conditions are recognized based on the grant-date fair value over the requisite service period using the accelerated attribution method to the extent achievement of the performance condition is probable. As of each reporting date, the Company estimates the probability that specified performance criteria will be met and does not recognize compensation expense until it is probable that the performance-based vesting condition will be achieved.

The Company evaluates whether an equity award should be classified and accounted for as a liability award or equity award for all equity-based compensation awards granted. As of March 31, 2026, all of the Company’s equity-based awards were equity classified. Forfeitures are recognized as they occur. The Company classifies equity-based compensation expense in the accompanying consolidated statements of operations and comprehensive loss in the same manner in which the award recipient’s salary and related costs are classified or in which the award recipient’s service payments are classified, as applicable.

Concentrations of Credit Risk and Significant Suppliers

Financial instruments that potentially expose the Company to credit risk primarily consist of cash, cash equivalents and marketable securities. The Company’s investment portfolio is comprised of money market funds, debt securities issued by U.S. government and corporate debt securities. The Company maintains its deposits with accredited financial institutions and, consequently, the Company does not believe it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships. Bank accounts in the United States are insured by the Federal Deposit Insurance Corporation (“FDIC”) up to $250,000. As of March 31, 2026 and December 31, 2025, predominantly all of the Company’s primary operating accounts significantly exceeded the FDIC limits.

The Company is dependent on third-party organizations to research, develop, manufacture and process its product candidates for its development programs. In particular, the Company currently relies on a limited number of third-party manufacturers for preclinical, clinical, and future commercial manufacturing activities. The Company expects to continue to be dependent on a small number of manufacturers to supply it with its requirements for all products. The Company’s research and development programs could be adversely affected by a significant interruption in the supply of the necessary materials.

Off-Balance Sheet Arrangements

As of March 31, 2026 and December 31, 2025, the Company had no off-balance sheet risks such as foreign exchange contracts, option contracts or other foreign hedging arrangements.

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Comprehensive Loss

Comprehensive loss includes net loss as well as other changes in stockholders' equity that result from transactions and events other than those with stockholders. The Company’s unrealized gains and losses on marketable securities represent the only component of other comprehensive loss that are excluded from the reported net loss and that are presented in the condensed consolidated statements of comprehensive loss.

Net Loss Per Share

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

The Company calculates basic net loss per common share by dividing net loss by the weighted-average number of common shares outstanding for the period, which includes pre-funded warrants to purchase common stock. The Company has generated a net loss in the periods presented so the basic and diluted net loss per share are the same as the inclusion of the potentially dilutive securities would be anti-dilutive.

Recently Issued Accounting Pronouncements

In November 2024, the FASB issued ASU 2024‑03, Disaggregation of Income Statement Expenses, which requires additional disclosures related to specified income statement expense categories on an annual and interim basis. The guidance is effective for annual periods beginning after December 15, 2026, and interim periods beginning after December 15, 2027, with early adoption permitted. The guidance may be applied prospectively or retrospectively. The Company is currently evaluating the impact of this guidance on its disclosures.

Marketable Securities

The following is a summary of the Company’s investing portfolio (in thousands):


	AS OF MARCH 31, 2026
			UNREALIZED
	COST		GAINS		LOSSES			FAIR VALUE
Marketable securities:
Maturities within one year:
U.S. treasury securities	$	274,711	$	133	$	(104	)	$	274,740
Debt securities issued by U.S. government agencies		107,724		92		(26	)		107,790
Commercial paper		19,288		—		(6	)		19,282
Corporate debt securities		206,461		31		(216	)		206,276
Total maturities within one year		608,184		256		(352	)		608,088
Maturities between one and two years:
U.S. treasury securities	$	155,403	$	12	$	(528	)	$	154,887
Debt securities issued by U.S. government agencies		8,557		—		(21	)		8,536
Corporate debt securities		35,047		3		(119	)		34,931
Total maturities between one and two years		199,007		15		(668	)		198,354
Total marketable securities	$	807,191	$	271	$	(1,020	)	$	806,442

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	AS OF DECEMBER 31, 2025
			UNREALIZED
	COST		GAINS		LOSSES			FAIR VALUE
Marketable securities:
Maturities within one year:
U.S. treasury securities	$	221,182	$	430	$	—		$	221,612
Debt securities issued by U.S. government agencies		127,796		324		—			128,120
Commercial paper		69,534		22		—			69,556
Corporate debt securities		179,230		136		(11	)		179,355
Total maturities within one year		597,742		912		(11	)		598,643
Maturities between one and two years:
U.S. treasury securities	$	128,396	$	149	$	—		$	128,545
Debt securities issued by U.S. government agencies		14,580		16		—			14,596
Corporate debt securities		29,583		16		(10	)		29,589
Total maturities between one and two years		172,559		181		(10	)		172,730
Total marketable securities	$	770,301	$	1,093	$	(21	)	$	771,373

As of March 31, 2026, the Company had 172 securities with a total fair market value of $527.7 million in an unrealized loss position. The Company does not intend to sell its investments before recovery of the amortized cost basis of its debt securities at maturity and no allowance for credit losses was recorded as of March 31, 2026 and December 31, 2025. Securities are evaluated at the end of each reporting period. The Company did not record any impairment related to its marketable securities during the three months ended March 31, 2026 and 2025.

Fair Value Measurements

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


	AS OF MARCH 31, 2026
	LEVEL 1		LEVEL 2		LEVEL 3		TOTAL
Cash equivalents:
Money market funds	$	441,502	$	—	$	—	$	441,502
U.S. treasury securities		3,190		—		—		3,190
Marketable securities:
U.S. treasury securities		429,627		—		—		429,627
Debt securities issued by U.S. government agencies		—		116,326		—		116,326
Commercial paper		—		19,282		—		19,282
Corporate debt securities		—		241,207		—		241,207
Total	$	874,319	$	376,815	$	—	$	1,251,134


	AS OF DECEMBER 31, 2025
	LEVEL 1		LEVEL 2		LEVEL 3		TOTAL
Cash equivalents:
Money market funds	$	86,669	$	—	$	—	$	86,669
U.S. treasury securities		5,903		—		—		5,903
Commercial paper		—		26,428		—		26,428
Marketable securities:
U.S. treasury securities		350,157		—		—		350,157
Debt securities issued by U.S. government agencies		—		142,716		—		142,716
Commercial paper		—		69,556		—		69,556
Corporate debt securities		—		208,944		—		208,944
Total	$	442,729	$	447,644	$	—	$	890,373

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Prepaids and Other Assets

Prepaid expenses and other current assets consisted of the following (in thousands):


	MARCH 31, 2026		DECEMBER 31, 2025
Prepaid manufacturing	$	1,560	$	1,090
Prepaid clinical		524		637
Prepaid other		3,367		2,873
Interest receivable		7,281		5,961
Other current assets		1,180		605
Total	$	13,912	$	11,166

As of March 31, 2026 and December 31, 2025, the Company had $8.3 million and $8.5 million, respectively, in long-term prepayments, made in conjunction with the Company's research and development activities, classified within other non-current assets.

Property and Equipment, net

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


	MARCH 31, 2026			DECEMBER 31, 2025
Leasehold improvements	$	3,075		$	3,075
Furniture and fixtures		1,760			1,760
Lab equipment		1,469			1,469
IT equipment		992			992
Less: Accumulated depreciation		(2,016	)		(1,608	)
Total	$	5,280		$	5,688

The Company recognized $0.4 million and $0.2 million of depreciation expense for the three months ended March 31, 2026 and 2025, respectively.

Accrued Expenses

Accrued expenses consisted of the following (in thousands):


	MARCH 31, 2026		DECEMBER 31, 2025
Accrued clinical expenses	$	9,062	$	9,178
Accrued manufacturing expenses		8,159		5,889
Accrued external research and development expenses		2,501		3,231
Accrued employee compensation		6,254		3,658
Accrued other		2,601		1,225
Total	$	28,577	$	23,181

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Other Significant Agreements

Paragon Option and License Agreements

No research and development expense related to services provided by Paragon Therapeutics, Inc. (“Paragon”) under the Option and License Agreements (as defined below) was recognized for the three months ended March 31, 2026. For the three months ended March 31, 2025, the Company recognized an immaterial amount of research and development expense in connection with services provided by Paragon under the Option and License Agreements (as defined below).

Option Agreements

In February 2022, the Company entered into an antibody discovery and option agreement with Paragon, which was subsequently amended in November 2022 (as amended, the “2022 Option Agreement”). Under the terms of the 2022 Option Agreement, Paragon identifies, evaluates and develops antibodies directed against certain mutually agreed therapeutic targets of interest to the Company. The 2022 Option Agreement initially included two selected targets, IL-13 and IL-4Rα, and was subsequently amended in November 2022 to include an additional selected target, OX40L. Under the 2022 Option Agreement, the Company has the exclusive option to, on a research program-by-research program basis, be granted an exclusive, worldwide license to all of Paragon’s right, title and interest in and to the intellectual property resulting from the applicable research program to develop, manufacture and commercialize the antibodies and products directed to the selected targets (each, an “Option”). From time to time, the Company can choose to add additional targets to the collaboration by mutual agreement with Paragon.

Pursuant to the terms of the 2022 Option Agreement, the parties initiated certain research programs that generally focused on a particular target (each, a “Research Program”). Each Research Program is aimed at discovering, generating, identifying and/or characterizing antibodies directed to the respective target. For each Research Program, the parties established a research plan that sets forth the activities that will be conducted, and the associated research budget (each, a “Research Plan”). Upon execution of the 2022 Option Agreement, the Company agreed with Paragon on an initial Research Plan that outlined the services that will be performed commencing at inception of the arrangement related to IL-13 and IL-4Rα. The Research Plan for OX40L was agreed to prior to December 31, 2022. The Company's exclusive option with respect to any future Research Program is exercisable at the Company's sole discretion at any time during the period beginning on the initiation of activities under the associated Research Program and ending a specified number of days following the delivery of the data package from Paragon related to the results of the Research Plan activities (the “Option Period”). There is no payment due upon exercise of an Option pursuant to the 2022 Option Agreement.

In consideration for the exclusive options granted under the 2022 Option Agreement, the Company paid an upfront cash amount of $1.3 million and issued 1,250,000 common units to Paragon. Paragon was also entitled to up to an additional 3,750,000 of common units in exchange for the rights granted under the 2022 Option Agreement, which were issued in connection with the closings of the additional tranches of the Series A preferred unit financing. Under the 2022 Option Agreement, on a Research Program-by-Research Program basis following the finalization of the Research Plan for each respective Research Program, the Company is required to pay Paragon a nonrefundable fee in cash of $0.5 million. The Company is also obligated to compensate Paragon on a quarterly basis for its services performed under each Research Program based on the actual costs incurred.

In November 2023, the Company entered into an additional antibody discovery and option agreement with Paragon (the “2023 Option Agreement” and together with the 2022 Option Agreement, collectively, the “Option Agreements”). Under the terms of the 2023 Option Agreement, Paragon identifies, evaluates and develops antibodies directed against certain mutually agreed therapeutic targets of interest to the Company. The 2023 Option Agreement initially includes one target, TSLP. Under the 2023 Option Agreement, the Company has the exclusive option to, on a research program-by-research program basis, be granted an exclusive, worldwide license to all of Paragon’s right, title and interest in and to the intellectual property resulting from the applicable research program to develop, manufacture and commercialize the antibodies and products directed to the selected targets. From time to time, the Company can choose to add additional targets to the collaboration by mutual agreement with Paragon.

Pursuant to the terms of the 2023 Option Agreement, the parties may initiate Research Programs. Each Research Program will be aimed at discovering, generating, identifying and/or characterizing antibodies directed to the respective target. For each Research Program, the parties must establish a Research Plan. In January 2024, the Company and Paragon agreed on an initial Research Plan that outlined the services that will be performed commencing at inception of the arrangement related to TSLP. The Company's exclusive option with respect to each Research Program is exercisable at the Company's sole discretion at any time during the period beginning on the initiation of activities under the associated Research Program and ending a specified number of days following the delivery of

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the data package from Paragon related to the results of the Research Plan activities. There is no payment due upon exercise of an Option pursuant to the 2023 Option Agreement.

Under the 2023 Option Agreement, on a Research Program-by-Research Program basis following the finalization of the Research Plan for each respective Research Program, the Company is required to pay Paragon a nonrefundable fee in cash of $2.0 million. The Company is also obligated to compensate Paragon on a quarterly basis for its services performed under each Research Program based on the actual costs incurred. The Company expenses the service fees as the associated costs are incurred when the underlying services are rendered. In January 2024, the Company finalized the Research Plan with Paragon related to the TSLP target. As such, the Company made a one-time non-refundable payment of $2.0 million to Paragon in the first quarter of 2024.

Unless terminated earlier, the Option Agreements shall continue in force on a Research Program-by-Research Program basis until the earlier of: (i) the end of the Option Period for such Research Program, as applicable, if such Option is not exercised by the Company; and (ii) the effective date of the license agreement for such Research Program if the Company exercises its Option with respect to such Research Program (the “Term”). Upon the expiration of the Term for all then-existing Research Programs, the applicable Option Agreement, will automatically expire in its entirety. The Company may terminate either Option Agreement or any Research Program at any time for any or no reason upon 30 days’ prior written notice to Paragon, provided that the Company must pay certain unpaid fees due to Paragon upon such termination, as well as any non-cancellable obligations reasonably incurred by Paragon in connection with its activities under any terminated Research Program. Each party has the right to terminate either Option Agreement or any Research Program upon (i) 30 days’ prior written notice of the other party’s material breach that remains uncured for the 30-day period and (ii) the other party’s bankruptcy.

License Agreements

In November 2022, the Company exercised its option available under the 2022 Option Agreement with respect to the IL-13 Research Program. Upon such exercise, the parties entered into an associated license agreement (the “IL-13 License Agreement”). In April 2023, the Company exercised its option available under the 2022 Option Agreement with respect to the IL- 4Rα Research Program and the OX40L Research Program. Upon such exercise, the parties entered into associated license agreements (the “IL-4Rα License Agreement” and the “OX40L License Agreement,” respectively). In August 2024, the Company exercised its option available under the 2023 Option Agreement with respect to the TSLP Research Program and entered into the associated license agreement (the “TSLP License Agreement” and collectively with the IL-13 License Agreement, the IL-4Rα License Agreement and the OX40L License Agreement, the “License Agreements”). Under the terms of the License Agreements, Paragon granted to the Company an exclusive, worldwide, royalty-bearing, sublicensable right and license with respect to certain information, patent rights and sequence information related to antibodies directed at the respective target to use, make, sell, import, export and otherwise exploit the antibodies directed at the respective target. Pursuant to the License Agreements, the Company granted to Paragon a similar license (except that such license the Company granted to Paragon is non-exclusive) to the respective licenses with respect to multispecific antibodies that are directed at the respective targets and one or more other antibodies. The Company was also granted a right of first negotiation with Paragon concerning the development, license and grant of rights to certain multispecific antibodies associated with each respective license. The Company is solely responsible for the continued development, manufacture and commercialization of products at its own cost and expense for each licensed target.

Under the IL-13 License Agreement, the IL-4Rα License Agreement and the OX40L License Agreement, the Company is obligated to pay Paragon up to $3.0 million upon the achievement of specific development and clinical milestones for the first product under each of the License Agreements that achieves such specified milestones, including a payment of $1.0 million upon the nomination of a development candidate and $2.0 million upon the first dosing of a human patient in a Phase 1 trial. Under the TSLP License Agreement, the Company is obligated to pay Paragon up to $28.0 million upon the achievement of specific development and clinical milestones for the first product, including a payment of $3.0 million upon the nomination of a development candidate and $5.0 million upon the first dosing of a human patient in a Phase 1 trial.

Upon execution of the IL‑13 License Agreement, the Company paid Paragon a $1.0 million fee for the nomination of a development candidate. In August 2023, the Company announced the dosing of its first participant in the Phase 1 trial of zumilokibart (APG777) and made a milestone payment of $2.0 million in the fourth quarter of 2023. In November 2023, the Company finalized the nomination of a development candidate under the IL‑4Rα License Agreement and made a milestone payment of $1.0 million to Paragon in the fourth quarter of 2023. In March 2024, the Company announced the dosing of its first participant in a Phase 1 trial of APG808 and made a milestone payment of $2.0 million to Paragon in the first quarter of 2024. In May 2024, the Company finalized the nomination of a development candidate under the OX40L License Agreement and made a milestone payment of $1.0 million to Paragon in the second quarter of 2024. In August 2024, the Company announced the dosing of its first participant in the Phase 1 trial of APG990 and made a milestone payment of $2.0 million to Paragon in the third quarter of 2024. In October 2024, the Company finalized the nomination of a development candidate under the TSLP License Agreement and made a milestone payment of $3.0 million to Paragon

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in the fourth quarter of 2024. In December 2024, the Company announced the dosing of its first participant in the Phase 1 trial of APG333 and made a milestone payment of $5.0 million in the fourth quarter of 2024.

The Company is also obligated to pay royalties to Paragon equal to a low-single digit percentage of net sales of any products under each of the respective License Agreements, and Paragon has a similar obligation to pay royalties to the Company with respect to each of the multispecific licenses. Royalties are due on a product-by-product and country-by-country basis beginning upon the first commercial sale of each product and ending on the later of (i) 12 years after the first commercial sale of such product in such country and (ii) expiration of the last valid claim of a patent covering such product in such country (the “Royalty Term”).

Unless earlier terminated, the License Agreements remain in effect until the expiration of the last-to-expire Royalty Term for any and all products associated with the respective license. The Company may terminate the agreement in its entirety or on a country-by-country or product-by-product at any time for any or no reason upon 60 days’ advance written notice to Paragon, and either party may terminate for (i) the other party’s material breach that remains uncured for 90 days (or 30 days with respect to any failure to make payments) following notice of such breach and (ii) the other party’s bankruptcy. Upon any termination prior to the expiration of a License Agreement, all licenses and rights granted pursuant to such License Agreement will automatically terminate and revert to the granting party and all other rights and obligations of the parties will terminate.

Biologics Master Services Agreement — WuXi Biologics (Hong Kong) Limited

In June 2022, Paragon and WuXi Biologics (Hong Kong) Limited (“WuXi Biologics”) entered into a biologics master services agreement (the “WuXi Biologics MSA”), which was subsequently novated to the Company by Paragon in the second quarter of 2023. The WuXi Biologics MSA governs all development activities and GMP manufacturing and testing for zumilokibart (APG777), APG990, APG333 and APG808, as well as potential future product candidates, on a work order basis. Under the WuXi Biologics MSA, the Company is obligated to pay WuXi Biologics a service fee and all non-cancellable obligations in the amount specified in each work order associated with the agreement for the provision of services.

The WuXi Biologics MSA terminates on the later of (i) June 20, 2027 or (ii) the completion of services under all work orders executed by the parties prior to June 20, 2027, unless terminated earlier. The term of each work order terminates upon completion of the services under such work order, unless terminated earlier. The Company can terminate the WuXi Biologics MSA or any work order at any time upon 30 days’ prior written notice and immediately upon written notice if WuXi Biologics fails to obtain or maintain required material governmental licenses or approvals. Either party may terminate a work order (i) at any time upon six months’ prior notice with reasonable cause, provided however that if WuXi Biologics terminates a work order in such manner, no termination or cancellation fees shall be paid by the Company and (ii) immediately for cause upon (a) the other party’s material breach that remains uncured for 30 days after notice of such breach, (b) the other party’s bankruptcy or (c) a force majeure event that prevents performance for a period of at least 90 days.

For the three months ended March 31, 2026 and March 31, 2025, the Company recognized $5.2 million and $1.2 million, respectively, of research and development expense in connection with the WuXi Biologics MSA.

Cell Line License Agreement — WuXi Biologics (Hong Kong) Limited

In June 2022, Paragon and WuXi Biologics entered into a cell line license agreement (the “Cell Line License Agreement”), which was subsequently novated to the Company by Paragon in the second quarter of 2023. Under the Cell Line License Agreement, the Company received a non-exclusive, worldwide, sublicensable license to certain of WuXi Biologics’ know-how, cell line, biological materials (the “WuXi Biologics Licensed Technology”) and media and feeds to make, have made, use, sell and import certain therapeutic products produced through the use of the cell line licensed by WuXi Biologics under the Cell Line License Agreement (the “WuXi Biologics Licensed Products”). Specifically, the WuXi Biologics Licensed Technology is used to manufacture zumilokibart (APG777), APG990, APG333 and APG808.

In consideration for the license, the Company has paid WuXi Biologics a non-refundable license fee of $150,000. Additionally, if the Company manufactures all of its commercial supplies of bulk drug product with a manufacturer other than WuXi Biologics or its affiliates, the Company is required to make royalty payments to WuXi Biologics in an amount equal to a fraction of a single digit percentage of global net sales of WuXi Biologics Licensed Products manufactured by a third-party manufacturer (the “Royalty”). If the Company manufactures part of its commercial supplies of the WuXi Biologics Licensed Products with WuXi Biologics or its affiliates, then the Royalty will be reduced accordingly on a pro rata basis.

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The Cell Line License Agreement will continue indefinitely unless terminated (i) by the Company upon six months’ prior written notice and the payment of all undisputed amounts due to WuXi Biologics through the effective date of termination, (ii) by WuXi Biologics for a material breach by the Company that remains uncured for 60 days after written notice, (iii) by WuXi Biologics if the Company fails to make a payment and such failure continues for 30 days after receiving notice of such failure, or (iv) by either party upon the other party’s bankruptcy.

Master Services Agreement and Project Specific Agreements — Samsung Biologics Limited

In March 2025, the Company entered into a Master Services Agreement (the “Samsung Biologics MSA”), made effective as of February 28, 2025, with Samsung Biologics Co., Ltd. (“Samsung Biologics”), pursuant to which Samsung Biologics will manufacture and supply the Company with zumilokibart (APG777) drug substance (the “Samsung Biologics Product”) for clinical development and commercial sale, if approved. The Company is obligated to pay Samsung Biologics service fees for each manufactured batch, as well as the costs of materials purchased by Samsung Biologics and expenses including testing and storage, which such costs and fees will be specified in Project Specific Agreements (each a “PSA”).

Also in March 2025, the Company entered into a PSA (the “Initial PSA”) with Samsung Biologics, made effective as of February 28, 2025, pursuant to which Samsung Biologics will produce clinical batches of the Samsung Biologics Product at its facility in Incheon, South Korea, perform process characterization and validation, and manufacture process performance qualification lots of the Samsung Biologics Product. Under the Initial PSA, the Company must purchase certain minimum quantities of the Samsung Biologics Product and has agreed to pay Samsung Biologics as determined pursuant to the terms of the Initial PSA.

The Samsung Biologics MSA will terminate in February 2035, or, if a PSA is still in effect, when such PSA terminates, and may be extended upon mutual agreement of the parties. The Initial PSA will terminate in December 2034. Either the Company or Samsung Biologics may terminate the Samsung Biologics MSA or the Initial PSA in the event of an uncured material breach by, insolvency of or inability to perform due to a force majeure event by the other party. In the event all applicable PSAs have been terminated, Samsung Biologics has agreed to provide assistance with certain technology transfer matters, subject to exceptions. If the Company terminates the Samsung Biologics MSA or Initial PSA without cause, the Company will generally be responsible for paying the purchase price for the Company’s aggregate product commitment for the remainder of the term, less any amounts the Company has already paid.

In February 2026, the Company entered into a separate PSA with Samsung that would provide for the commercial manufacture of zumilokibart (APG777) drug substance should the program eventually receive regulatory approval. If specific circumstances render Apogee unable to proceed with commercial distribution, the PSA provides for Samsung to receive compensation, including for contractually obligated expenses, and an exit fee in the high single-digit millions.

For the three months ended March 31, 2026 and 2025, the Company recognized $0.4 million and $1.7 million, respectively, of research and development expense in connection with the Samsung Biologics MSA.

Commitments and Contingencies

Other Contracts

Currently, all of the Company’s preclinical, clinical and commercial drug manufacturing, storage, distribution or quality testing are outsourced to third-party manufacturers. As development programs progress and new process efficiencies are built, the Company expects to continually evaluate this strategy with the objective of satisfying demand for registration trials and, if approved, the manufacture, sale and distribution of commercial products. Under such agreements, the Company is contractually obligated to make certain payments to vendors upon early termination, including to reimburse them for their unrecoverable outlays incurred prior to cancellation as well as any amounts owed by the Company prior to early termination. The actual amounts the Company could pay in the future to the vendors under such agreements may differ from the purchase order amounts due to cancellation provisions.

Indemnification Agreements

The Company enters into standard indemnification agreements and/or indemnification sections in other agreements in the ordinary course of business. Pursuant to the agreements, the Company indemnifies, holds harmless, and agrees to reimburse the indemnified party for losses suffered or incurred by the indemnified party, generally the Company’s business partners. The term of these indemnification agreements is generally perpetual any time after execution of the agreement. There is no limit to the maximum potential amount of future payments the Company could be required to make under these indemnification agreements. As of March 31, 2026, the

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Company has not incurred costs to defend lawsuits or settle claims related to these indemnification agreements. The Company was not aware of any claims under these indemnification arrangements as of March 31, 2026 and December 31, 2025.

Legal Proceedings

The Company is not currently party to any material legal proceedings. At each reporting date, the Company evaluates whether or not a potential loss amount or a potential range of loss is probable and reasonably estimable under the provisions of FASB ASC Topic 450, Contingencies (“ASC 450”). The Company expenses as incurred the costs related to its legal proceedings.

10.

Stockholders' Equity

Common Stock

In July 2023, the Company completed its initial public offering (“IPO”), selling an aggregate of 20,297,500 shares of common stock. Net proceeds were $315.4 million, after deducting underwriting discounts and commissions and other offering expenses. All outstanding preferred units were exchanged into 24,987,750 shares of common stock in connection with the IPO. Following the IPO, the Company is authorized to issue up to 400,000,000 shares of common stock, par value $0.00001.

In March 2024, the Company issued and sold an aggregate of 7,790,321 shares of its common stock in an underwritten public offering. Net proceeds were $450.0 million, after deducting underwriting discounts and commissions and other offering expenses.

In August 2024, the Company entered into an Open Market Sale Agreement (the “Sale Agreement”) with Jefferies LLC (the “Sales Agent”), pursuant to which the Company may offer and sell shares of common stock up to a maximum aggregate offering price of $300.0 million through an at-the-market offering program. In December 2024, the Company sold 926,049 shares of common stock under the ATM Facility for gross proceeds of $44.9 million, less commissions and other offering expenses of $1.4 million. During the year ended December 31, 2025, the Company sold 1,175,701 shares of common stock under the ATM Facility for gross proceeds of $67.6 million, less commissions and other offering expenses of $2.0 million. During the three months ended March 31, 2026, the Company sold 369,220 shares of common stock under the ATM Facility for gross proceeds of $29.7 million, less commissions and other offering expenses of $0.8 million. As of March 31, 2026, $157.8 million remained available for sale under the Sale Agreement.

In October 2025, the Company issued and sold an aggregate of 8,048,782 shares of its common stock and in lieu of common stock to certain investors, pre-funded warrants to purchase up to 365,853 shares of common stock in an underwritten public offering. Net proceeds were $324.1 million, after deducting underwriting discounts and commissions and other offering expenses.

In March 2026, the Company issued and sold an aggregate of 5,750,000 shares of its common stock in an underwritten public offering. Net proceeds were $377.4 million, after deducting underwriting discounts and commissions and other offering expenses.

As of March 31, 2026, 75,323,726 and 74,882,396 shares of common stock were issued and outstanding, respectively. The 75,323,726 shares of common stock issued are comprised of 61,395,754 shares of voting common stock, 13,486,642 shares of non-voting common stock and 441,330 shares of unvested restricted common stock.

As of December 31, 2025, 69,038,943 and 68,401,349 shares of common stock were issued and outstanding, respectively. The 69,038,943 shares of common stock issued are comprised of 54,914,707 shares of voting common stock, 13,486,642 shares of non-voting common stock and 637,594 shares of unvested restricted common stock.

Shares underlying pre‑funded warrants are excluded from shares of common stock issued and outstanding for all periods presented.

Warrants

In October 2025, the Company issued pre‑funded warrants to purchase up to 365,853 shares of common stock at an exercise price of $0.00001 per share. The pre‑funded warrants were exercisable immediately and are not subject to expiration. As of March 31, 2026, none of the pre-funded warrants have been exercised.

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11.

Equity-Based Compensation

Restricted Common Stock

The following table provides a summary of the unvested restricted common stock award activity during the three months ended March 31, 2026:


	NUMBER OF SHARES			WEIGHTED- AVERAGE GRANT DATE FAIR VALUE PER SHARE
Unvested restricted common stock as of December 31, 2025		637,594		$	5.69
Vested		(194,060	)		4.98
Forfeited		(2,204	)		7.62
Unvested restricted common stock as of March 31, 2026		441,330		$	5.99

The fair value of restricted common stock awards vested during the three months ended March 31, 2026 was $1.0 million.

Stock Options and Restricted Stock Units

In July 2023, in connection with the IPO, the Company’s Board of Directors (the “Board”) and stockholders approved the 2023 Equity Incentive Plan (the “2023 Plan”), which became effective on July 13, 2023. The 2023 Plan provides for the grant of incentive stock options, non-qualified stock options, stock appreciation rights, awards of restricted stock, restricted stock units and other stock-based awards. As of March 31, 2026, 7,804,838 shares of common stock were available for future grant under the 2023 Plan. The number of shares available for grant and issuance under the 2023 Plan is automatically increased on January 1 of each year by a number of shares equal to up to 5% of the outstanding shares of common stock on such date.

The Company uses the Black-Scholes option pricing model to estimate the fair value of stock options granted with the following assumptions:


		THREE MONTHS ENDED MARCH 31,
		2026
Risk-free interest rate		3.6% - 4.0%
Expected dividend yield		0.0%
Expected term (in years)		6.0 - 6.25
Expected volatility		74.4% - 75.2%

The following table provides a summary of stock option activity during the three months ended March 31, 2026:


	OPTIONS			WEIGHTED- AVERAGE EXERCISE PRICE		WEIGHTED- AVERAGE REMAINING CONTRACTUAL TERM (IN YEARS)		AGGREGATE INTRINSIC VALUE (IN THOUSANDS)
Outstanding as of December 31, 2025		5,610,444		$	36.95		8.56	$	216,170
Granted		1,395,882			75.84		—		—
Exercised		(139,814	)		30.90		—		—
Forfeited		(25,076	)		46.47		—		—
Outstanding as of March 31, 2026		6,841,436		$	44.97		8.62	$	268,156
Exercisable as of March 31, 2026		2,165,555		$	34.06		8.10	$	108,508

The total intrinsic value of options exercised during the three months ended March 31, 2026 was $6.3 million.

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The following table provides a summary of the unvested restricted stock unit activity under the 2023 Plan during the three months ended March 31, 2026:


	NUMBER OF SHARES			WEIGHTED- AVERAGE GRANT DATE FAIR VALUE PER SHARE
Unvested restricted stock units as of December 31, 2025		177,615		$	39.36
Granted		213,851			76.98
Vested		(27,953	)		51.81
Forfeited		(4,879	)		51.54
Unvested restricted stock units as of March 31, 2026		358,634		$	60.66

The fair value of restricted stock units vested during the three months ended March 31, 2026 was $1.4 million.

2023 Employee Stock Purchase Plan

In July 2023, the Board adopted and the Company’s stockholders approved the 2023 Employee Stock Purchase Plan (the “ESPP”), which became effective on July 13, 2023. The ESPP provides that eligible employees may contribute up to 15% of their eligible earnings toward the semi-annual purchase of the Company's common stock, subject to any plan limitations. The purchase period under the ESPP has a duration of six months, and the purchase price with respect to each purchase period is equal to 85% of the lesser of (i) the fair market value of the Company's common stock at the commencement of the applicable six-month purchase period or (ii) the fair market value of the Company's common stock on the exercise date. As of March 31, 2026, 69,405 shares have been issued under the ESPP and 2,157,626 shares remain available for issuance.

The following table presents the classification of equity-based compensation expense related to equity awards granted to employees, executives, and service providers (in thousands):


	THREE MONTHS ENDED MARCH 31,
	2026		2025
Research and development expense	$	8,527	$	5,372
General and administrative expense		8,628		5,754
Total	$	17,155	$	11,126

As of March 31, 2026, the total unrecognized compensation expense related to the Company’s stock options, unvested restricted stock and ESPP was $180.7 million, which the Company expects to recognize over a weighted-average period of approximately 2.6 years.

12.

Related Parties

The Company considers Paragon to be a related party because Fairmount Funds Management LLC, which beneficially owns more than 5% of Paragon, beneficially owns more than 5% of the Company’s capital stock and, as of the date of this Quarterly Report, has one seat on the Board. Under the Option Agreements and the License Agreements, Paragon, received upfront consideration in the form of common units, is entitled to receive milestone and royalty payments upon specific conditions and receives payments from the Company for providing ongoing services under the agreements (see Note 8). As of March 31, 2026 and December 31, 2025, $0.6 million and $2.1 million were due to Paragon, respectively. For the three months ended March 31, 2026, the Company incurred research and development expenses of $0.6 million with Paragon. For the three months ended March 31, 2025, the Company incurred immaterial research and development expenses with Paragon.

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13.

Net Loss Per Share

Basic and diluted net loss per share attributable to common stockholders was calculated as follows (in thousands, except share and per share data):


	THREE MONTHS ENDED MARCH 31,
	2026			2025
Numerator:
Net loss	$	(74,111	)	$	(55,339	)
Net loss attributable to common stockholders, basic and diluted	$	(74,111	)	$	(55,339	)
Denominator:
Weighted average shares of common stock outstanding, basic and diluted		69,668,439			58,195,272
Net loss per share attributable to common stockholders, basic and diluted	$	(1.06	)	$	(0.95	)

The following potential common shares, presented based on amounts outstanding at period end, were excluded from the calculation of diluted net loss per share attributable to common stockholders for the period indicated because including them would have been anti-dilutive:


	THREE MONTHS ENDED MARCH 31,
	2026		2025
Stock options		6,841,436		5,355,989
Unvested restricted common stock		441,330		1,221,369
Unvested restricted stock units		358,634		245,244
Potential shares issuable under the ESPP		10,043		13,825
Total		7,651,443		6,836,427

14.

Operating Leases

In November 2023, the Company entered into a lease agreement for lab space. In June 2024, the agreement was amended to expand the space and extend the lease term through November 2026, with the option to extend for one year. In January 2025, the agreement was amended to further expand the space. As of March 31, 2026, the remaining lease term was 0.7 years and the weighted average incremental borrowing rate used to determine the operating lease liability was 9.1%.

In September 2024, the Company entered into a lease agreement for office space. The lease term is five years with two one-year options to extend. As of March 31, 2026, the remaining lease term was 3.5 years and the incremental borrowing rate used to determine the operating lease liability was 6.0%.

As of March 31, 2026, total current and non-current operating lease liabilities were $3.1 million and $4.9 million, respectively. The Company incurred lease expense of $1.1 million and $1.1 million for the three months ended March 31, 2026 and 2025, respectively.

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15.

Segment Information

The Company has one operating segment and one reporting unit. The Company’s chief operating decision maker (“CODM”), its Chief Executive Officer, manages the Company’s operations on a consolidated basis for the purposes of assessing performance and allocating resources. All of the Company’s assets are located in the United States.

The following table summarizes the Company’s segment information for the periods presented (in thousands):


	THREE MONTHS ENDED MARCH 31,
	2026			2025
Operating expenses(1):
Research and development personnel-related (excluding equity-based compensation)	$	18,542		$	15,296
External research and development costs - zumilokibart (APG777)		19,542			14,571
External research and development costs - APG990 / APG279		5,444			3,213
External research and development costs - APG333 / APG273		254			2,434
External-discovery related costs and other (2)		8,433			5,437
General and administrative personnel-related (excluding equity-based compensation)		7,985			5,707
General and administrative operations(3)		5,009			5,105
Equity-based compensation		17,155			11,126
Depreciation expense		408			207
Interest income, net		(8,740	)		(7,840	)
Provision for income taxes		79			83
Consolidated net loss	$	74,111		$	55,339

(1)

The significant expense categories and amounts align with the segment-level information that is regularly provided to the CODM.

(2)

External-discovery related costs and other include expenses related to APG808.

(3)

General and administrative operations are comprised of finance, investor relations, business development, human resources, legal, facilities & IT, and certain overhead expenses.

16.

Subsequent Events

The Company evaluated subsequent events through the date on which these financial statements were issued to ensure that these condensed consolidated financial statements include appropriate disclosure of events both recognized in the financial statements as of March 31, 2026 and events which occurred subsequently but not recognized in the financial statements. No subsequent events have occurred that require disclosure.

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Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations

You should read the following discussion of our financial condition and results of operations in conjunction with the condensed consolidated financial statements and related notes included elsewhere in this Quarterly Report, as well as our audited consolidated financial statements and the related notes included in our Annual Report on Form 10-K filed with the Securities and Exchange Commission (“SEC”). The following discussion contains forward-looking statements that reflect our current plans, forecasts, estimates and beliefs and involve risks and uncertainties. Our historical results are not necessarily indicative of the results that may be expected for any period in the future. Our actual results, outcomes and the timing of events could differ materially from those discussed in the forward-looking statements. Factors that could cause or contribute to these differences include those discussed below and elsewhere in this Quarterly Report, particularly in the section titled “Special Note Regarding Forward Looking Statements” and “Risk Factors.” We urge you to consider these factors carefully in evaluating the forward-looking statements contained in this Quarterly Report. Forward-looking statements are not historical facts, reflect our current views with respect to future events, and apply only as of the date made. We do not intend, and undertake no obligation, to update these forward-looking statements, except as required by law. Unless the context requires otherwise, references to “we,” “us,” “our,” “Apogee” or “the Company” refer to Apogee Therapeutics, Inc. and its subsidiaries.

This Quarterly Report contains references to our programs, which are used interchangeably to refer to our clinical programs within our pipeline and our products under development.

Overview

We are a clinical stage biotechnology company advancing optimized, novel biologics with the potential for differentiated efficacy and dosing in the largest inflammatory and immunology (“I&I”) markets, including for the treatment of atopic dermatitis (“AD”), asthma, eosinophilic esophagitis (“EoE”), chronic obstructive pulmonary disease (“COPD”), and other I&I indications. Our antibody programs are designed to overcome limitations of existing therapies by targeting well-established mechanisms of action and incorporating advanced antibody engineering to optimize half-life and other properties.

Our pipeline comprises multiple antibody programs being developed initially for the treatment of I&I indications as monotherapies and combinations, including zumilokibart (APG777), APG279 (zumilokibart + APG990), APG273 (zumilokibart + APG333), and APG808 (each a “program” or “product candidate”). With four validated targets in our portfolio, we are seeking to achieve best-in-class efficacy and dosing through monotherapies and combinations of our novel antibodies. Based on a broad pipeline and depth of expertise, we believe we can deliver value and meaningful benefit to patients underserved by today’s standard of care. We believe each of our product candidates has potential for broad application across multiple I&I indications.

Zumilokibart (APG777) – anti-IL13 antibody

Zumilokibart is a subcutaneous (“SQ”) extended half-life monoclonal antibody (“mAb”) targeting IL-13.

Phase 1 Trial in Healthy Volunteers

In August 2023, we initiated a Phase 1 trial of zumilokibart in healthy volunteers. The zumilokibart Phase 1 trial was a double-blind, placebo-controlled study in healthy volunteers and consisted of a single-ascending dose (“SAD”) component and a multiple ascending dose component. Eight healthy volunteers, six treated with zumilokibart and two treated with placebo, were enrolled in each cohort, and we enrolled a total of 40 healthy adult subjects in the trial.

In March 2024, we announced positive interim safety and pharmacokinetic (“PK”) data from this trial with zumilokibart demonstrating a potential best-in-class PK profile, including a half-life of 77 days, supporting the potential for every three- to six- month maintenance dosing in AD. Single doses of zumilokibart demonstrated a deep and sustained effect on pharmacodynamic (“PD”) markers out to approximately 12 months. Zumilokibart was well-tolerated across all dose groups.

APEX Phase 2 Trial for Patients with AD

In May 2024, we announced dosing of our first patient in the APEX Phase 2 clinical trial, which is a randomized, placebo-controlled study evaluating zumilokibart in patients with moderate-to-severe AD.

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In July 2025, we announced positive 16-week data from the Part A portion of the APEX Phase 2 clinical trial. Part A of the trial enrolled 123 adult patients who were randomized 2:1 to zumilokibart versus placebo and received an induction regimen dosing of 720mg at Weeks 0 and 2, followed by 360mg at Weeks 4 and 12. The primary endpoint for the induction arm of Part A was percentage change in Eczema Area Severity Index (“EASI”) score from baseline at Week 16. Secondary endpoints included EASI-75, EASI-90, Validated Investigator Global Assessment (“vIGA”) 0/1 and Itch Numeric Rating Scale (“Itch NRS”) at Week 16. In non-head-to-head trial comparisons, the initial 16-week findings from Part A included efficacy results, which compared favorably versus standard of care across endpoints, as well as rapid onset of itch relief and lesion reduction, and a favorable safety profile consistent with its class.

The Part A trial met its primary endpoint, with zumilokibart showing significantly greater least squares mean percent change from baseline at Week 16 with an EASI reduction of 71.0% compared to placebo of 33.8% (p < 0.001). Zumilokibart showed the highest absolute and placebo-adjusted EASI-75 of any biologic in a 16-week global study with 66.9% of patients treated with zumilokibart achieving EASI-75 compared to 24.6% on placebo (p < 0.001). Pre-specified sensitivity analysis showed consistent results in both moderate and severe patients based on baseline EASI score. The results demonstrated a vIGA 0/1 of 34.9% compared to placebo of 17.3% (p < 0.05) and an EASI-90 of 33.9% compared to placebo of 14.7% (p < 0.05). Treatment of patients with zumilokibart led to rapid and deep onset of itch relief and achieved a statistically significant reduction by Week 1, with a 50.7% reduction of Itch NRS from baseline compared to placebo of 23.2% (p < 0.01) at Week 16. Zumilokibart was well-tolerated, with 56.1% of zumilokibart -exposed patients experiencing treatment-emergent adverse events (“TEAEs”) (vs. 63.4% in placebo). The most common TEAEs, occurring in more than 5% of patients, were non-infective conjunctivitis (14.6% vs. 2.4% in placebo), upper respiratory tract infection (8.5% vs 12.2% in placebo), nasopharyngitis (4.9% vs. 12.2% in placebo), and pain in extremity (0.0% vs. 7.3% in placebo) with the latter three being numerically lower in zumilokibart treated patients compared to placebo. Serious TEAEs were rare for zumilokibart -exposed patients (1.2% vs. 2.4% in placebo). The discontinuation rate due to adverse events was low for zumilokibart -exposed patients (2.4%). There were no injection site reactions in the zumilokibart treated group. In addition, improvement in asthma and sinusitis, as measured by improvements in the Asthma Control Questionnaire and Sinonasal Outcome Test in patients with comorbid asthma or sinusitis, was observed, which reflect zumilokibart’s potential to broadly impact Type 2 inflammatory disease.

All Part A patients that benefited from treatment in the induction arm received the opportunity to continue to zumilokibart maintenance treatment, which evaluated three and six-month dosing intervals. Patients in the placebo arm for the first 16 weeks also received the opportunity to receive an induction regimen of zumilokibart followed by three-month dosing of zumilokibart.

In March 2026, we announced positive 52‑week maintenance data from the Part A portion of the APEX Phase 2 clinical trial. The 52‑week maintenance portion of the trial evaluated 360mg of zumilokibart administered at three‑month and six‑month maintenance dosing intervals. Results focused on two analysis populations: the Week 16 zumilokibart responder population and the full 52-week zumilokibart-treated population. At Week 52, zumilokibart demonstrated strong maintenance of response among Week 16 responders, with deepening of efficacy across the full treated population for all lesion and itch endpoints. Among Week 16 responders, 75% and 85% of patients receiving three‑month and six‑month maintenance dosing, respectively, maintained EASI‑75. In addition, 86% and 78% of patients receiving three‑month and six‑month maintenance dosing, respectively, maintained a vIGA 0/1 at Week 52. Across the entire population treated with zumilokibart, responses improved through Week 52 for both every three - and six -month dosing regimens. vIGA 0/1 response of 72% and 52% was achieved at Week 52 for patients receiving three-month and six-month maintenance dosing, respectively, an improvement of 35% and 14% from Week 16 for the three-month and six-month dosing regimens, respectively. In addition, EASI-90 of 75% and 48% was achieved at Week 52 for patients receiving three-month and six-month maintenance dosing regimens, respectively, an improvement of 36% and 10% from Week 16 for the three-month and six-month regimens, respectively. EASI-100 of 41% and 19% was achieved at Week 52 for patients receiving three-month and six-month maintenance dosing regimens, respectively, an improvement of 33% and 11% from Week 16 for the three-month and six-month dosing regimens, respectively. Of patients who achieved EASI-90 at Week 16, 88% of patients with every 3-month dosing and 72% of patients with every 6-month dosing maintained such response at Week 52.

Zumilokibart was generally well tolerated over the 52‑week treatment period, with a safety profile consistent with other agents in its class. The most commonly reported TEAEs included non-infective conjunctivitis, upper respiratory tract infection, and nasopharyngitis.

In February 2025, we announced that we had commenced dosing of the Part B portion of the APEX Phase 2 trial. Part B is testing low, medium (Part A dose), and high dose regimens against placebo. In January 2026, we announced that we completed Part B enrollment ahead of schedule and exceeded target enrollment with a total of 347 patients. We expect to report 16-week topline induction data from Part B in the second quarter of 2026. Subject to positive results and regulatory alignment with the U.S. Food and Drug Administration (the “FDA”), we plan to initiate Phase 3 trials in AD in the second half of 2026, enabling a potential launch of zumilokibart for the treatment of AD in 2029.

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The APEX Part A induction regimen was designed to exceed EBGLYSS exposures by approximately 30% to 40% with potential for improved clinical outcomes and a maintenance regimen designed to equal lebrikizumab’s exposures. The results at Week 16 of the Part A study showed that patients in the highest zumilokibart exposure quartile (n=19) achieved the highest clinical response of any quartile in a post hoc exposure-response analysis. These patients had a mean 84.0% reduction in EASI from baseline, 89.5% of patients reaching EASI-75, 63.2% achieving IGA0/1, and 63.2% achieving EASI-90, demonstrating a robust response at the highest exposure level. The highest zumilokibart Part B dose was designed to exceed EBGLYSS exposures by approximately 90 to 100% which is similar to the exposure obtained in the highest quartile of the Part A results.

Phase 1b Trial in Patients with Asthma

In April 2025, we initiated a Phase 1b trial of zumilokibart (APG777) in patients with mild-to-moderate asthma, and in January 2026, we announced positive interim data from the trial. The trial is a double-blind, placebo-controlled trial evaluating the safety and tolerability of zumilokibart in patients with mild-to-moderate asthma. The trial is designed to also evaluate fractional exhaled nitric oxide (“FeNO”) suppression, a biomarker of Type 2 inflammation that has shown the strongest correlation with exacerbations in asthma. The trial enrolled 31 adult patients who were randomized 3:1 to zumilokibart versus placebo and participants received a single dose of 720 mg of zumilokibart or placebo on day 1. Nineteen of the patients with mild-to-moderate asthma had a FeNO baseline ≥25 ppb, representative of asthma with Type 2 inflammation, and as a result met the pre-specified criteria for the analysis population.

In the trial, zumilokibart demonstrated a favorable safety profile and was well-tolerated in all patients. In the 14 patients treated with zumilokibart in the analysis population, the only TEAEs observed in more than one patient was gastroesophageal reflux disease (“GERD”), which was observed in 2 patients. In the analysis population, there were no Grade 3 or higher TEAEs or serious adverse events observed and no conjunctivitis, injection site reactions, or anti-drug antibodies were observed. In the full safety population (n=31) that were on treatment (n=23), TEAEs occurring in more than one patient on zumilokibart were upper respiratory tract infection (n=3), nasopharyngitis (n=2), GERD (n=2), and arthralgia (n=2); there were no Grade 3 or higher TEAEs or serious adverse events.

Zumilokibart demonstrated robust and durable suppression of FeNO following a single dose in the analysis population. A maximum absolute mean FeNO reduction of 45 ppb (60% decrease from baseline) after a single dose was observed in the analysis population. Durable FeNO suppression through 16 weeks was observed for all patients in the analysis population. Zumilokibart also demonstrated suppression of FeNO through 32 weeks for those patients in the analysis population with follow up available at the time of the data cut (n=3), supporting the potential for three- or six- month dosing. In the trial, positive trends were observed in forced expiratory volume in one second (“FEV1”) and across Type 2 biomarkers for all available data in the analysis population. FEV1 is a PD measure of lung function. Based on these results, we anticipate sharing our plans in the second half of 2026 to further evaluate zumilokibart in the ASPIRE Phase 2 asthma trial.

Expansion Opportunities in Other Indications

We expect that results from the Phase 1b trial of zumilokibart for the treatment of asthma, in addition to topline induction data from the Part B portion of the APEX Phase 2 trial in AD, will allow us to determine dose selections for further expansion indications in 2027 and beyond, including but not limited to asthma and EoE. We expect to announce plans for the Phase 2 ASPIRE trial for the treatment of asthma and the Phase 2 ELEVATE trial for the treatment of EoE in the second half of 2026. Based on our clinical data, we expect to further evaluate additional opportunities to develop zumilokibart for other I&I indications, including alopecia areata, chronic rhinosinusitis with nasal polyps, chronic spontaneous urticaria, and prurigo nodularis.

In addition, we plan to evaluate zumilokibart in combination with other investigational therapies within our pipeline to potentially enable greater efficacy for I&I conditions. The first of these combinations is APG279, which combines zumilokibart with APG990, our novel, SQ, half-life extended mAb targeting OX40L. We are also evaluating APG273, which combines zumilokibart with APG333, our novel, SQ, half-life extended mAb targeting thymic stromal lymphopoietin (“TSLP”).

APG279 – Combination of zumilokibart (APG777) and APG990 – anti-OX40L antibody

We are developing zumilokibart and APG990 together as APG279, a potential first-in-class coformulation for the treatment of AD by combining deep and sustained inhibition of Type 2 inflammation via zumilokibart’s inhibition of IL-13 with broader inhibition of Type 1-3 inflammation through APG990’s inhibition of OX40L. APG990 is an SQ extended half-life mAb that utilizes advanced antibody engineering to target OX40L.

In August 2024, we initiated a Phase 1 clinical trial of APG990, which was designed as a double-blind, placebo-controlled, first-in-human, SAD trial designed to evaluate the safety and PK of APG990 in 40 healthy adult participants across five cohorts. Doses of

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SQ APG990 evaluated in the study included 75mg, 150mg, 300mg, 600mg and 1,200mg. In March 2025, we announced positive interim safety and PK data from the trial. PK data showed a half-life of approximately 60 days across doses tested. APG990, in single doses up to 1,200mg, was well-tolerated and showed a favorable safety profile, consistent with other assets targeting OX40L. The most common (≥10%) TEAEs were headache. 53% of participants observed at least one TEAE and there were no Grade 3 TEAEs related to study drug or severe adverse events. No adverse events led to study discontinuation. There were no cases of pyrexia or chills.

In July 2025, we commenced dosing in the Phase 1b trial of APG279 against DUPIXENT in patients with moderate-to-severe AD. Enrollment was completed with 86 patients, and we expect a data readout in the second half of 2026. The initial clinical trial of APG279 is being conducted as a coadministration of zumilokibart and APG990. We plan to advance the development of APG279 in future studies as a coformulation. The PK data for APG990, when considered together with APG279 coformulation data, provides the potential for dosing the combination two to four times per year with a single 2 mL coformulated injection.

APG273 – Combination of zumilokibart (APG777) and APG333 - anti-TSLP antibody

We are developing zumilokibart and APG333 together as APG273, a potential quarterly or less frequently dosed co-formulation for the treatment of asthma and COPD. APG333 is a fully-human mAb against TSLP, an epithelial cell-derived cytokine that has emerged as an attractive validated target for the treatment of people living with asthma and COPD, with the potential for extended half-life and to be used in combination with other mAbs for potentially greater efficacy in broader populations.

In December 2024, we initiated a Phase 1 clinical trial of APG333 in healthy volunteers, and in November 2025, we announced positive interim safety, PK and PD results from the clinical trial. APG333 demonstrated a half-life of approximately 55 days, supporting the potential for every three- and six-month dosing. In addition, key biomarkers of eosinophils and IL-5 showed depth of suppression in line with TSLP analogs and durability out to 6 months (limit of available follow-up).

APG333, with single doses of up to 1,000 mg, was well-tolerated across the four cohorts. The most common TEAEs occurring in ≥10% of APG333 treated participants were headache and upper respiratory tract infection. TEAEs were generally mild and self-limited and there were no dose dependent trends in TEAEs seen. There were no Grade 3 TEAEs or severe adverse events; and no adverse events led to study discontinuation.

We plan to announce additional clinical plans for APG273 in 2026 to support advancement into future combination trials in asthma and COPD.

APG808 – anti-IL4Rα antibody

APG808 is an SQ extended half-life mAb targeting IL-4Rα, a target with clinical validation across eight different Type 2 allergic diseases. In March 2024, we commenced dosing of the first healthy volunteers in the APG808 Phase 1 trial, and in September 2024, we commenced dosing of the first asthma patients as a cohort in that Phase 1 trial. In December 2024, we announced positive interim safety, PK and PD data from the Phase 1 trial. APG808 demonstrated a potential best-in-class PK profile, including a half-life of approximately 55 days at projected, clinically relevant steady state exposures, supporting the potential for every two- to three-month maintenance dosing. Single doses of APG808 demonstrated a deep and sustained effect on PD markers out to approximately three months (longest follow-up available at time of data cut). APG808 was well-tolerated across all dose groups.

In May 2025, we announced positive interim results from the Phase 1b trial of APG808 in patients with mild-to-moderate asthma. The trial was a double-blind, placebo-controlled, multiple-dose trial, which evaluated the safety and tolerability of APG808 in 22 adult patients with mild-to-moderate asthma. The trial also evaluated FeNO, thymus and activation-regulated chemokine (“TARC”), and pSTAT6. Participants were randomized 3:1, receiving 600mg of APG808 or placebo on day 1 and day 29.

The results demonstrated that APG808 was well-tolerated, with multiple doses of APG808 resulting in rapid suppression of FeNO, with a maximal robust FeNO decrease from baseline of 53% and sustained FeNO decrease from baseline of 50% at 12 weeks. APG808 also demonstrated sustained and near-complete reduction in pSTAT6 as well as deep reduction of TARC maintained through 12 weeks. The most common TEAEs observed were headache, injection site erythema, and upper respiratory tract infections. There were no Grade 3 TEAEs or severe adverse events, and no adverse events led to study discontinuation.

APG808’s optimized PK profile coupled with FeNO suppression out to 12-weeks reinforces the potential for 2-months or longer maintenance dosing, offering a significant advantage compared to the current bi-weekly standard of care.

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Recent Developments

The following summarizes key business developments for the three months ended March 31, 2026, excluding program updates discussed in the “Overview” section above.

Equity Offerings

On March 26, 2026, pursuant to our Registration Statement on Form S-3, which became effective in August 2024 (File No 333-281503), we issued and sold an aggregate of 5,750,000 shares of common stock (inclusive of 750,000 shares of common stock pursuant to the exercise in full of the underwriters’ option to purchase additional shares) at a public offering price of $70.00 per share (the “March 2026 Offering”). The aggregate net proceeds from the offering were $377.4 million after deducting underwriting discounts and commissions, and estimated offering expenses payable by us.

ATM Facility

During the three months ended March 31, 2026, we sold 369,220 shares of common stock under our at the market offering program (“ATM Facility”) for gross proceeds of $29.7 million, less commissions and other offering expenses of $0.8 million.

Net Loss

We have incurred significant operating losses since inception. Our ability to generate product revenue sufficient to achieve profitability will depend heavily on the successful development and eventual commercialization of any programs we may develop. We generated a net loss of $74.1 million for the three months ended March 31, 2026. As of March 31, 2026, we had an accumulated deficit of $635.9 million. We expect to continue to incur significantly increased expenses for the foreseeable future if and as we continue to operate our business.

Macroeconomic Conditions

The global macroeconomic environment is uncertain, and could be negatively affected by, among other things, financial market volatility and uncertainty, inflation, interest rate fluctuations, changing tariff policies and trade restrictions, uncertainty with respect to the federal budget and debt ceiling and potential government shutdowns related thereto, instability in the global banking system, cybersecurity events, the impact of war or military conflict, including regional conflicts around the world, and public health pandemics. We closely monitor the impact of these factors on all aspects of our business, including the potential impacts on our clinical trials, supply chain, regulatory interactions, employees, third-party partners, suppliers, and vendors. The ultimate impact of global and domestic economic conditions on our business remains highly uncertain and will depend on future developments and factors that continue to evolve. As a result, we are subject to continuing risks and uncertainties and continue to closely monitor the impact of the current conditions on our business. For more information regarding these risks and uncertainties, see the section titled “Risk Factors” in this Quarterly Report.

Collaboration, License and Service Agreements

For information regarding our collaboration, license and service agreements, see Note 8—Other Significant Agreements to our condensed consolidated financial statements included in this Quarterly Report.

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Overview of Financial Results

Revenue

We have not generated any revenue from product sales and do not expect to generate any revenue from the sale of products for several years, if at all. If our development efforts for our programs are successful and result in regulatory approval or collaboration or license agreements with third parties, we may generate revenue in the future from product sales or payments from collaboration or license agreements that we may enter into with third parties, or any combination thereof.

Operating Expenses

Our operating expenses consist of (i) research and development expenses and (ii) general and administrative expenses.

Research and Development

Research and development expenses consist primarily of costs incurred in connection with the development and research of our programs. These expenses include:

•

the cost of developing and validating our manufacturing process for use in our preclinical studies and current and future clinical trials;

•

expenses incurred in connection with continuing our current research programs and preclinical development of any programs we may identify, including under agreements with third parties, such as consultants and contractors;

•

costs of funding research performed by third parties, including Paragon, that conduct research and development and preclinical or clinical activities on our behalf;

•

the cost to acquire in-process research and development, with no alternative future use associated with asset acquisitions, such as the Option Agreements, and License Agreements;

•

expenses incurred under agreements with clinical trial sites and clinical research organizations (“CROs”) that conduct research and development activities on our behalf, including clinical trial execution, project management, data management and related outsourced services;

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costs related to production of clinical supplies and preclinical materials, including fees paid to contract manufacturers; and

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personnel-related expenses, including salaries, bonuses and equity-based compensation expense.

We measure and recognize asset acquisitions or licenses to intellectual property that are not deemed to be business combinations based on the cost to acquire or license the asset or group of assets, which includes transaction costs. In an asset acquisition or license to intellectual property, the cost allocated to acquired in-process research and development, with no alternative future use is recognized as research and development expense on the acquisition date.

We expense research and development costs as incurred. Non-refundable advance payments that we make for goods or services to be received in the future for use in research and development activities are recorded as prepaid expenses. The prepaid amounts are expensed as the related goods are delivered or the services are performed, or when it is no longer expected that the goods will be delivered or the services rendered.

Our primary focus since inception has been the identification and development of our pipeline programs. Our research and development costs primarily consist of external costs, including CRO fees and fees paid to Paragon under the Option Agreements and the License Agreements. We do not separately track or segregate the amount of costs incurred under the Option Agreements due to the early-stage and discovery nature of the services. We do not allocate personnel-related costs by program because these resources are used and these costs are deployed across multiple programs under development, and, as such, are not separately classified.

We expect that our research and development expenses will increase substantially for the foreseeable future as we continue to invest in research and development activities for our programs, and any potential future programs, including investments in clinical trials and manufacturing. The success of programs we may identify and develop will depend on many factors, including the following:

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timely and successful completion of preclinical studies;

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effective Investigational New Drug applications (“INDs”) or comparable foreign applications that allow commencement of our planned clinical trials or future clinical trials for any programs we may develop;

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successful enrollment and completion of clinical trials;

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positive results from our future clinical trials that support a finding of safety and effectiveness, acceptable PK profile, and an acceptable risk-benefit profile in the intended populations;

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receipt of marketing approvals from applicable regulatory authorities;

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establishment of arrangements through our own facilities or with third-party manufacturers for clinical supply and, where applicable, commercial manufacturing capabilities;

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establishment, maintenance, defense and enforcement of patent, trademark, trade secret and other intellectual property protection or regulatory exclusivity for any products we may develop; and

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maintenance of a continued acceptable safety, tolerability and efficacy profile of any programs we may develop following approval.

Any changes in the outcome of any of these variables with respect to the development of programs that we may identify could mean a significant change in the costs and timing associated with the development of such programs. For example, if the U.S. Food and Drug Administration (“FDA”) or another regulatory authority were to require us to conduct clinical trials beyond those that we currently anticipate will be required for the completion of clinical development of a program, or if we experience significant delays in our clinical trials due to patient enrollment, macroeconomic events or other reasons, we would be required to expend significant additional financial resources and time on the completion of clinical development. We may never obtain regulatory approval for any of our programs.

General and Administrative

General and administrative expenses consist primarily of personnel-related expenses, including salaries, bonuses, and equity-based compensation, for individuals in our executive, finance, legal, IT operations, human resources, business development, commercial and other administrative functions. Other significant general and administrative expenses include legal fees relating to corporate matters, professional fees for accounting, auditing, tax and administrative consulting services, insurance costs and recruiting costs. These costs relate to the operation of the business, unrelated to the research and development function, or any individual program.

We expect that our general and administrative expenses will increase substantially for the foreseeable future as we increase our headcount to support the expected growth in our research and development activities and the potential commercialization of our product candidates, if approved. We also expect to continue incurring expenses associated with being a public company, including increased costs of accounting, audit, legal, regulatory and tax-related services associated with maintaining compliance with exchange listing and SEC requirements, director and officer insurance costs, and investor and public relations costs.

Other Income (Expense), Net

Interest Income

Interest income consists of interest income earned from our cash, cash equivalents, and marketable securities and amortization of investment discounts.

Income Taxes

Since our inception, we have not recorded any income tax benefits for the net losses we have incurred or for the research and development tax credits generated in each period as we believe, based upon the weight of available evidence, that it is more likely than not that all of our net operating loss (“NOL”) carryforwards and the vast majority of our tax credit carryforwards will not be realized.

As of December 31, 2025, we had U.S. federal NOL carryforwards of approximately $250.7 million, which may be available to reduce future taxable income and have an indefinite carryforward period but are limited in their usage to an annual deduction equal to 80% of annual taxable income. We also had state net operating loss carryforwards of approximately $94.3 million, which will begin to expire in 2043 for state tax purposes. As of December 31, 2025, we also had U.S. federal and research and development tax credit carryforwards of approximately $16.7 million, which may be available to reduce future tax liabilities. We also had California research and development credit carryforwards of approximately $2.9 million. Additionally, we had Massachusetts research and development credit carryforwards of approximately $1.7 million. The U.S. federal and Massachusetts research and development tax credit carryforwards expire at various dates beginning in 2042 and the California research and development tax credit carryforwards do not expire. We have recorded a full valuation allowance against our net deferred tax assets at the balance sheet date.

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Our provision for state income taxes was $0.1 million and $0.1 million for the three months ended March 31, 2026 and 2025, respectively.

Results of Operations

A discussion regarding our financial condition and results of operations for the three months ended March 31, 2026 compared to the three months ended March 31, 2025 is presented below.

Comparison of the Three Months Ended March 31, 2026 and 2025

Results of Operations

The following table summarizes our consolidated statements of operations for the periods presented (in thousands):


	THREE MONTHS ENDED MARCH 31,
	2026			2025			$ CHANGE
Operating expenses:
Research and development	$	60,819		$	46,387		$	14,432
General and administrative		21,953			16,709			5,244
Total operating expenses		82,772			63,096			19,676
Loss from operations		(82,772	)		(63,096	)		(19,676	)
Other income, net:
Interest income, net		8,740			7,840			900
Total other income, net		8,740			7,840			900
Net loss before taxes	$	(74,032	)	$	(55,256	)	$	(18,776	)
Provision for income taxes		(79	)		(83	)		4
Net loss after taxes	$	(74,111	)	$	(55,339	)	$	(18,772	)

Research and Development Expense

The following table summarizes our research and development expenses incurred for the periods presented (in thousands):


	THREE MONTHS ENDED MARCH 31,
	2026		2025
External research and development costs by program:
Zumilokibart (APG777)	$	19,542	$	14,571
APG990/APG279		5,444		3,213
APG333/APG273		254		2,434
Unallocated research and development costs:
External-discovery related costs and other(1)		8,433		5,437
Personnel-related (excluding equity-based compensation)		18,542		15,296
Equity-based compensation		8,527		5,372
Depreciation expense		77		64
Total research and development expenses	$	60,819	$	46,387

(1)

Includes research and development expenses related to APG808

Research and development expenses for the three months ended March 31, 2026 and 2025 were $60.8 million and $46.4 million, respectively. The increase of $14.4 million was primarily driven by the continued development of our zumilokibart (APG777) and APG990/APG279 programs, increased external-discovery related costs, and higher personnel and equity-based compensation expenses associated with the growth in our research and development team, partially offset by decreases in expenses related to the APG333/APG273 program.

Research and development expense related to the zumilokibart (APG777) program increased by $5.0 million in the three months ended March 31, 2026, compared to the three months ended March 31, 2025, primarily driven by an increase in clinical trial-related expenses associated with our APEX Phase 2 clinical trial. Research and development expense related to the APG990/APG279 program increased by $2.2 million in the three months ended March 31, 2026, compared to the three months ended March 31, 2025, primarily

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due to an increase in clinical manufacturing activities and clinical trial expenses. Research and development expense related to the APG333/APG273 program decreased by $2.2 million in the three months ended March 31, 2026, compared to the three months ended March 31, 2025, primarily due to a reduction in clinical manufacturing activities and decreases in preclinical research and development and clinical trial related expenses.

External-discovery related costs and other expenses increased by $3.0 million in the three months ended March 31, 2026, compared to the three months ended March 31, 2025, primarily driven by an increase in professional service fees. Additionally, personnel-related expenses and equity-based compensation both increased by $3.2 million in the three months ended March 31, 2026, compared to the three months ended March 31, 2025, primarily due to increased headcount and an increase in the fair value of equity awards granted.

General and Administrative Expense

The following table summarizes our general and administrative expenses for the periods presented (in thousands):


	THREE MONTHS ENDED MARCH 31,
	2026		2025
Personnel-related (excluding equity-based compensation)	$	7,985	$	5,707
Equity-based compensation		8,628		5,754
Legal and professional fees		1,232		1,395
Depreciation expense		331		143
Other		3,777		3,710
Total general and administrative expenses	$	21,953	$	16,709

General and administrative expenses for the three months ended March 31, 2026 were $22.0 million, compared to $16.7 million for the three months ended March 31, 2025. The increase of $5.3 million was primarily due to increases in equity-based compensation and personnel-related expenses of $2.9 million and $2.3 million, respectively, primarily driven by increased headcount and an increase in the fair value of equity awards granted. The increase in total general and administrative expense was the result of the expansion of our operations to support the growth in our business.

Other Income, Net

Interest income increased $0.9 million for t

Apogee Therapeutics, Inc. 10-Q