0001558370-24-007861 | 10-Q | XBRL Viewer

Fair Value Measurements - Measured at fair value on reoccurring basis (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	$ 330,739	$ 277,143
Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	808,050	387,798
Fair Value, Recurring \| Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	628,516	234,629
Fair Value, Recurring \| Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	179,534	153,169
Fair Value, Recurring \| Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	407,755	110,655
Fair Value, Recurring \| Money Market Funds \| Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	407,755	110,655
Fair Value, Recurring \| U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	69,556
Marketable securities	151,205	123,974
Fair Value, Recurring \| U.S. treasury securities \| Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	69,556
Marketable securities	151,205	123,974
Fair Value, Recurring \| US Treasury and Government
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	179,534	153,169
Fair Value, Recurring \| US Treasury and Government \| Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	$ 179,534	$ 153,169

Equity-Based Compensation - Summary of classification of equity-based compensation expense related to incentive units (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
Aug. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Equity-based compensation expense	$ 0	$ 4,186	$ 1,274
Research and development expense
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Equity-based compensation expense		1,930	133
General and administrative expense
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Equity-based compensation expense		$ 2,256	$ 1,141

Equity-Based Compensation - Summary of stock option activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
OPTIONS
Outstanding as of beginning	2,506,017
Granted	110,259
Exercised	(1,047)
Outstanding as of ending	2,615,229	2,506,017
Vested and expected to vest	2,615,229
Exercisable	99,955
WEIGHTED-AVERAGE EXERCISE PRICE
Outstanding as of beginning (in dollars per share)	$ 21.49
Granted (in dollars per share)	38.53
Exercised (in dollars per share)	22.86
Outstanding as of ending (in dollars per share)	22.21	$ 21.49
Vested and expected to vest (in dollars per share)	22.21
Exercisable (in dollars per share)	$ 22.93
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Additional Disclosures [Abstract]
Outstanding weighted-average remaining contractual term (in years)	9 years 7 months 9 days	9 years 9 months 18 days
Vested and expected to vest weighted-average remaining contractual term (in years)	9 years 7 months 9 days
Exercisable weighted-average remaining contractual term	9 years 4 months 17 days
Outstanding aggregate intrinsic value	$ 115,694	$ 16,154
Vested and expected to vest aggregate intrinsic value	115,694
Exercisable aggregate intrinsic value	4,350
Fair value units vested	$ 1,800

Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2024

Fair Value Measurements

Schedule of financial assets and liabilities measured at fair value on a reoccurring basis

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


	AS OF MARCH 31, 2024
	LEVEL 1		LEVEL 2		LEVEL 3		TOTAL
Cash equivalents:
Money market funds	$	407,755	$	—	$	—	$	407,755
U.S. treasury securities		69,556		—		—		69,556
Marketable securities:
U.S. treasury securities		151,205		—		—		151,205
Debt securities issued by U.S. government agencies		—		179,534		—		179,534
	$	628,516	$	179,534	$	—	$	808,050


	AS OF DECEMBER 31, 2023
	LEVEL 1		LEVEL 2		LEVEL 3		TOTAL
Cash equivalents:
Money market funds	$	110,655	$	—	$	—	$	110,655
Marketable securities:
U.S. treasury securities		123,974		—		—		123,974
Debt securities issued by U.S. government agencies		—		153,169		—		153,169
	$	234,629	$	153,169	$	—	$	387,798

CONDENSED CONSOLIDATED STATEMENT OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Cash flows from operating activities:
Net loss	$ (32,094)	$ (12,525)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation expense	29
Equity-based compensation expense	4,186	1,274
Amortization of discounts on marketable securities	(2,710)
Non-cash lease expense	266
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(1,462)	(44)
Accounts payable	2,159	477
Operating lease liability	(263)
Accrued expenses	(1,747)	261
Net cash used in operating activities	(31,636)	(10,557)
Cash flows from investing activities:
Purchases of marketable securities	(125,892)
Maturities of marketable securities	74,500
Purchases of property and equipment	(351)
Net cash used in investing activities	(51,743)
Cash flows from financing activities:
Proceeds from issuance of common stock, net of issuance costs	450,496
Proceeds from exercise of options	24
Net cash provided by financing activities	450,520
Increase (decrease) in cash, cash equivalents and restricted cash	367,141	(10,557)
Cash, cash equivalents and restricted cash, beginning of period	118,610	151,890
Cash, cash equivalents and restricted cash, end of period	485,751	141,333
Supplemental disclosures of non-cash activities:
Unpaid financing cost in accrued liability	541
Deferred financing issuance costs in accrued liability		406
Deferred financing issuance costs in accounts payable		70
Reconciliation of cash, cash equivalents and restricted cash:
Cash and cash equivalents	485,457	141,333
Restricted cash	294
Total	$ 485,751	$ 141,333

Summary of Significant Accounting Policies (Policies)

3 Months Ended

Mar. 31, 2024

Summary of Significant Accounting Policies

Basis of Presentation

The condensed consolidated financial statements prior to the Reorganization include the accounts of Apogee Therapeutics, LLC and its wholly-owned subsidiary. The condensed consolidated financial statements subsequent to the Reorganization include the accounts of Apogee Therapeutics, Inc. and its wholly-owned subsidiary.

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 of the Financial Accounting Standards Board (“FASB”). In the Company’s management opinion, the information furnished in these unaudited condensed consolidated financial statements reflect 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 reported interim 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, Apogee Biologics, Inc. 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.

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, 2024, 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
Laboratory equipment		5 years

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.

Preferred Units

The Company has classified the preferred units as temporary equity because the units could become effectively settled for cash or other assets due to certain contingent event clauses that are outside of the Company’s control. The preferred units are not currently settleable, but are entitled to a distribution of available proceeds upon a change of control or a sale event which is a bona fide, negotiated transaction in which the Company has determined to affect a change of control. Because the occurrence of a change of control and a sale event is not currently probable, the carrying values of the preferred units are not being accreted to their redemption values. Subsequent adjustments to the carrying values of the preferred units would be made only when the change of control or sale event becomes probable.

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. The Company makes estimates and judgments about future taxable income based on assumptions that are consistent with the Company’s plans and estimates. Should the actual amounts differ from these estimates, the amount of the Company’s valuation allowance could be materially impacted. Changes in these estimates may result in significant increases or decreases to the tax provision in a period in which such estimates are changed, which in turn would affect net income or loss.

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 and U.S. treasury securities.

Marketable Securities

The Company’s investments are comprised of U.S. government agency securities and U.S. treasury 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.

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 as current assets on the condensed consolidated balance sheets as they mature within one year from the balance sheet date.

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.

Equity-Based Compensation

Prior to the Reorganization, the Company issued equity-based awards to employees, managers, executives, non-employees and service providers in the form of common units and incentive units. Subsequent to the Reorganization, the Company issued equity-based awards to employees, managers, executives, non-employees and service providers in the form of restricted common units and stock options. The Company accounts for equity-based compensation awards in accordance with FASB ASC Topic 718, Compensation-Stock Compensation (“ASC 718”).

Due to the absence of an active market for the Company’s common units or incentive units prior to the completion of the IPO, the Company utilized methodologies in accordance with the framework of the American Institute of Certified Public Accountants Accounting and Valuation Guide, Valuation of Privately-Held Company Equity Securities Issued as Compensation, to estimate the fair value of its common units and incentive units. The estimated fair value of the common units and incentive units was determined at each grant date based upon a variety of factors, including the illiquid nature of the common units, arm’s-length sales of the Company’s equity units (including preferred units), the effect of the rights and preferences of the preferred unit unitholders, and the prospects of a liquidity event. Among other factors are the Company’s financial position and historical financial performance, the status of technological developments within the Company’s research, the composition and ability of the current research and management team, an evaluation or benchmark of the Company’s competition, and the current business climate in the marketplace. Significant changes to the key assumptions underlying the factors used could have resulted in different fair values of the common units and incentive units at each valuation date.

Subsequent to the completion of the IPO, 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 calculated based on reported volatility data for a representative group of publicly traded companies for which historical information is available. The Company selects companies with comparable characteristics with historical share price information that approximates the expected term of the equity-based awards. The Company computes the historical volatility data using the daily closing prices for the selected companies’ shares during the equivalent period that approximates the calculated expected term of the stock options. The Company will continue to apply this method until a sufficient amount of historical information regarding the volatility of its stock price becomes available. 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, 2024, 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 and debt securities issued by U.S. government. 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, 2024 and December 31, 2023, 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 relies on one third-party contract manufacturer to produce and process its two most advanced programs, APG777 and APG808, for preclinical and clinical 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. A significant amount of the Company’s research and development activities are performed under its agreements with Paragon (see Note 7).

Off-Balance Sheet Arrangements

As March 31, 2024 and December 31, 2023, the Company had no off-balance sheet risks such as foreign exchange contracts, option contracts or other foreign hedging arrangements.

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 follows the two-class method when computing net loss per share. Prior to the Reorganization, the Company issued units that met the definition of participating securities, including the Company’s Series A Preferred Units, the Series B Preferred Units, and vested incentive units (each a participating security), and subsequent to the Reorganization, 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. The two-class method determines net loss per unit and net loss per share for each class of common and participating securities according to dividends declared or accumulated and participation rights in undistributed earnings. The two-class method requires income for the period to be allocated between common and participating securities based upon their respective rights to share in the income as if all income for the period had been distributed. Prior to the Reorganization, during periods of loss, there was no allocation required under the two-class method since the participating securities did not have a contractual obligation to fund the losses of the Company. Subsequent to the Reorganization, 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.

Prior to the Reorganization, the Company calculated basic net loss per common share by dividing net loss by the weighted-average number of common units outstanding for the period. Subsequent to the Reorganization, 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. The Company has generated a net loss in the periods presented so the basic and diluted net loss per unit and net loss per share are the same as the inclusion of the potentially dilutive securities would be anti-dilutive.

For periods presented that include the Reorganization, including the three months ended March 31, 2023, the weighted-average shares of common stock outstanding include the weighted average number of common units outstanding prior to the Reorganization.

Equity-Based Compensation - Determining fair value of stock options (Details) - 2023 Equity Incentive Plan - Employee Stock Option	3 Months Ended
	Mar. 31, 2024 $ / shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Risk free interest rate, Minimum	3.90%
Risk free interest rate, Maximum	4.30%
Expected dividend yield	0.00%
Expected term	6 years 3 months
Expected volatility, Minimum	95.00%
Expected volatility, Maximum	96.40%
Minimum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common stock fair value (in dollars per share)	$ 33.50
Maximum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common stock fair value (in dollars per share)	$ 66.45

Fair Value Measurements

3 Months Ended

Mar. 31, 2024

Fair Value Measurements

Fair Value Measurements

4.Fair Value Measurements

The Company estimated the fair value of the Tranche Options, as defined below (see Note 10), at the time of issuance and subsequently remeasured them at each reporting period and prior to settlement, which occurred prior to December 31, 2022. The fair value of the Tranche Options was determined using a contingent forward model, which considered as inputs the estimated fair value of the preferred units as of each valuation date, the risk-free interest rate, probability of achievement, salvage value and estimated time to each tranche closing. The most significant assumptions in the contingent forward model impacting the fair value of the Tranche Options is the fair value of the Company’s Series A Preferred Unit, probability of achievement and time to the tranche closing as of each measurement date. The Company determined the fair value per share of the underlying preferred unit by taking into consideration the most recent sales of its preferred units, results obtained from third-party valuations and additional factors the Company deems relevant.


	AS OF MARCH 31, 2024
	LEVEL 1		LEVEL 2		LEVEL 3		TOTAL
Cash equivalents:
Money market funds	$	407,755	$	—	$	—	$	407,755
U.S. treasury securities		69,556		—		—		69,556
Marketable securities:
U.S. treasury securities		151,205		—		—		151,205
Debt securities issued by U.S. government agencies		—		179,534		—		179,534
	$	628,516	$	179,534	$	—	$	808,050


	AS OF DECEMBER 31, 2023
	LEVEL 1		LEVEL 2		LEVEL 3		TOTAL
Cash equivalents:
Money market funds	$	110,655	$	—	$	—	$	110,655
Marketable securities:
U.S. treasury securities		123,974		—		—		123,974
Debt securities issued by U.S. government agencies		—		153,169		—		153,169
	$	234,629	$	153,169	$	—	$	387,798

- Definition

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

+ References + Details

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Mar. 31, 2024	Mar. 31, 2023
Pay vs Performance Disclosure
Net Income (Loss)	$ (32,094)	$ (12,525)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(g)(1)(ii))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 323
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481687/323-10-50-3

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 825
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 28
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482907/825-10-50-28

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
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+ Details

Equity-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2024

Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]

Schedule of stock option activity


				WEIGHTED-
		WEIGHTED-		AVERAGE		AGGREGATE
		AVERAGE		REMAINING		INTRINSIC
		EXERCISE		CONTRACTUAL TERM		VALUE
	OPTIONS	PRICE		(IN YEARS)		(IN THOUSANDS)
Outstanding as of December 31, 2023	2,506,017	$	21.49		9.80		16,154
Granted	110,259	$	38.53		—		—
Exercised	(1,047)	$	22.86		—		—
Forfeited	—	$	—		—		—
Outstanding as of March 31, 2024	2,615,229	$	22.21		9.61		115,694
Vested and expected to vest as of March 31, 2024	2,615,229	$	22.21		9.61		115,694
Exercisable as of March 31, 2024	99,955	$	22.93		9.38		4,350

Schedule of restricted stock unit activity


		WEIGHTED-
		AVERAGE
	NUMBER OF	GRANT DATE FAIR
	SHARES	VALUE PER SHARE
Unvested restricted stock units as of December 31, 2023	144,090	$	22.86
Vested	(8,988)		22.86
Unvested restricted stock units as of March 31, 2024	135,102	$	22.86

Schedule of equity-based compensation expense

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



	THREE MONTHS		THREE MONTHS
	ENDED MARCH 31,		ENDED MARCH 31,
	2024		2023
Research and development expense	$	1,930	$	133
General and administrative expense		2,256		1,141
Total	$	4,186	$	1,274

Incentive Units

Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]

Schedule of fair value assumptions of share based payment


		THREE MONTHS ENDED
		MARCH 31,
		2023
Risk free interest rate		4.3%
Expected dividend yield		0.0%
Expected term (in years)		0.71-2.25
Expected volatility		77.0%

Unvested restricted common stock

Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]

Schedule of activity of equity instrument other than option


		WEIGHTED-
		AVERAGE
	NUMBER OF	GRANT DATE FAIR
	SHARES	VALUE PER SHARE
Unvested restricted common stock as of December 31, 2023	2,316,902	$	5.31
Vested	(228,677)	$	4.12
Unvested restricted common stock as of March 31, 2024	2,088,225	$	5.44

2023 Equity Incentive Plan | Employee Stock Option

Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]

Schedule of fair value assumptions of share based payment


		THREE MONTHS ENDED
		MARCH 31,
		2024
Common stock fair value		$33.50 - $66.45
Risk free interest rate		3.9% - 4.3%
Expected dividend yield		0.0%
Expected term (in years)		6.25
Expected volatility		95.0% - 96.4%

CONDENSED CONSOLIDATED STATEMENT OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
CONDENSED CONSOLIDATED STATEMENT OF COMPREHENSIVE LOSS
Net loss	$ (32,094)	$ (12,525)
Change in unrealized losses on marketable securities, net of tax	(506)
Comprehensive loss	$ (32,600)	$ (12,525)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

+ Details

Nature of the Business

3 Months Ended

Mar. 31, 2024

Nature of the Business

Nature of the Business

1.Nature of the Business

Apogee Therapeutics, Inc., together with its consolidated subsidiary (collectively, “Apogee” or the “Company”), a successor to Apogee Therapeutics, LLC, is a biotechnology company seeking to develop differentiated biologics for the treatment of atopic dermatitis, asthma, chronic obstructive pulmonary disease and related inflammatory and immunology indications with high unmet need. The Company’s antibody programs are designed to overcome limitations of existing therapies by leveraging clinically validated mechanisms and incorporating advanced antibody engineering to optimize half-life and other properties designed.

The Company commenced its operations in February 2022 as a Delaware limited liability company named Apogee Therapeutics, LLC. The Company was founded by leading healthcare investors, Fairmount Funds and Venrock Healthcare Capital Partners and has since assembled a management team of drug developers with significant experience in clinical development. As a result of the Reorganization (as defined below) and in connection with the Company’s initial public offering (“IPO”) in July 2023, the Company directly wholly owns the assets of Apogee Therapeutics, LLC, including the stock of its subsidiary. In addition, the Company engages third parties, including Paragon Therapeutics, Inc. (“Paragon”), who is also a related party, to perform ongoing research and development and other services on its behalf.

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 rights, 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. 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.

In November 2022, the Company exercised its option available under the 2022 Option Agreement with respect to the IL-13 Research Program (as defined below) and, in April 2023, the Company exercised its options available under the 2022 Option Agreement with respect to the IL-4Rα Research Program and the OX40L Research Program. Upon such exercises, the parties entered into associated license agreements for each target. Under the terms of each license agreement, 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. The Company is solely responsible for the development, manufacture and commercialization of IL-13, IL-4Rα and OX40L product candidates and products at its own cost and expense.

On July 13, 2023, the Company completed a reorganization, pursuant to which the members of Apogee Therapeutics, LLC contributed their units in Apogee Therapeutics, LLC to Apogee Therapeutics, Inc. in exchange for shares of common stock or non-voting common stock of Apogee Therapeutics, Inc. and Apogee Therapeutics, LLC became a wholly-owned subsidiary of Apogee Therapeutics, Inc. (the “Reorganization”), as follows:

●

holders of Series A Preferred Units of Apogee Therapeutics, LLC received 7,678,000 shares of non-voting common stock of Apogee Therapeutics, Inc.;

●

holders of Series B Preferred Units of Apogee Therapeutics, LLC received 11,501,108 shares of common stock and 5,808,642 shares of non-voting common stock of Apogee Therapeutics, Inc.;

●

holders of common units of Apogee Therapeutics, LLC received 1,919,500 shares of common stock of Apogee Therapeutics, Inc.;

●

holders of vested incentive units of Apogee Therapeutics, LLC received 690,188 shares of common stock of Apogee Therapeutics, Inc.; and

●

holders of unvested incentive units of Apogee Therapeutics, LLC received 2,779,358 shares of restricted common stock of Apogee Therapeutics, Inc.

On July 18, 2023, the Company completed its IPO, pursuant to which it issued and sold an aggregate of 20,297,500 shares of its common stock (inclusive of 2,647,500 shares pursuant to the exercise of the underwriters’ overallotment option in full) at the IPO price of $17.00 per share for net cash proceeds of $315.4 million, after deducting underwriting discounts and commissions and other offering expenses. The shares of Apogee Therapeutics, Inc. began trading on the Nasdaq Global Market on July 14, 2023 under the symbol APGE. On March 12, 2024, the Company issued and sold an aggregate of 7,790,321 shares of its common stock (inclusive of 1,016,128 shares pursuant to the exercise in full of the underwriters’ option to purchase additional shares) at a public offering price of $62.00 per share, for aggregate net proceeds of $450.0 million after deducting underwriting discounts and commissions and other offering expenses.

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 two most advanced programs currently under development, APG777 and APG808, as well as other programs, 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 $155.9 million as of March 31, 2024. Further, the Company incurred a net loss of $32.1 million and experienced negative cash flows from operations of $31.6 million for the three months ended March 31, 2024. Based on the Company’s current operating plan, it estimates that its existing cash and cash equivalents of $485.5 million, and marketable securities of $330.7 million as of March 31, 2024, 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.

Preferred Shares (Details) - USD ($) $ / shares in Units, $ in Millions	Jul. 18, 2023	Nov. 15, 2022	Feb. 24, 2022	Mar. 31, 2023
Preferred Shares
Preferred Units, units issued				65,089,212
Preferred Units, units outstanding				65,089,212
Preferred Units, units authorized				65,089,212
Preferred Units, units converted	24,987,750
Series A Preferred Units
Preferred Shares
Preferred Units, units authorized				20,000,000
Series A Preferred Units \| Tranche Option
Preferred Shares
Initial proceeds of issuance of preferred units			$ 1.1
Series A Preferred Units \| Series A Agreement
Preferred Shares
Preferred Units, units issued			5,000,000
Maximum number of issue and sell of preferred shares			20,000,000
Preferred units purchase price (in dollars per share)			$ 1.00
Gross cash proceeds			$ 5.0
Net issuance cost			$ 0.2
Series A Preferred Units \| Series A Agreement \| Tranche Option
Preferred Shares
Preferred Units, units issued			5,000,000
Gross cash proceeds			$ 20.0
Series B Preferred Units
Preferred Shares
Preferred Units, units authorized				45,089,212
Series B Preferred Units \| Series B Agreement
Preferred Shares
Maximum number of issue and sell of preferred shares		45,089,212
Gross cash proceeds		$ 149.0
Net issuance cost		$ 0.5
Temporary equity preferred shares purchase price (in dollars per share)		$ 3.30456

Nature of the Business (Details) $ / shares in Units, $ in Thousands			1 Months Ended	3 Months Ended
	Mar. 12, 2024 USD ($) $ / shares shares	Jul. 18, 2023 USD ($) $ / shares shares	Nov. 30, 2022 item	Mar. 31, 2024 USD ($) shares	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)	Jul. 13, 2023 shares
Nature of the Business
Net proceeds from IPO \| $	$ 450,000	$ 315,400
Accumulated deficit \| $				$ (155,864)		$ (123,770)
Net Income (Loss) \| $				(32,094)	$ (12,525)
Negative cash flows from operations \| $				(31,636)	(10,557)
Cash and cash equivalents \| $				485,457	$ 141,333
Marketable securities \| $				$ 330,739		$ 277,143
IPO
Nature of the Business
Shares issued	7,790,321	20,297,500
Share price \| $ / shares	$ 62.00	$ 17.00
Overallotment option
Nature of the Business
Shares issued	1,016,128	2,647,500		7,790,321
Apogee Therapeutics, LLC \| Common Units
Nature of the Business
Common stock shares issued							1,919,500
Apogee Therapeutics, LLC \| Vested incentive units
Nature of the Business
Common stock shares issued							690,188
Apogee Therapeutics, LLC \| Unvested incentive units
Nature of the Business
Common stock shares issued							2,779,358
Apogee Therapeutics, LLC \| Series A Preferred Units
Nature of the Business
Nonvoting common stock shares issued							7,678,000
Apogee Therapeutics, LLC \| Series B Preferred Units
Nature of the Business
Nonvoting common stock shares issued							5,808,642
Common stock shares issued							11,501,108
Option Agreement \| Related party \| Paragon Therapeutics, Inc
Nature of the Business
Number of selected targets initially included under the agreement \| item			2

Marketable Securities

3 Months Ended

Mar. 31, 2024

Marketable Securities

Marketable Securities

3.Marketable Securities

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


	AS OF MARCH 31, 2024
			UNREALIZED
	COST		GAINS		LOSSES		FAIR VALUE
Marketable securities:
U.S. treasury securities	$	151,251	$	13	$	(59)	$	151,205
Debt securities issued by U.S. government agencies		179,665		24		(155)		179,534
	$	330,916	$	37	$	(214)	$	330,739


	AS OF DECEMBER 31, 2023
			UNREALIZED
	COST		GAINS		LOSSES		FAIR VALUE
Marketable securities:
U.S. treasury securities	$	123,836	$	140	$	(2)	$	123,974
Debt securities issued by U.S. government agencies		152,978		199		(8)		153,169
	$	276,814	$	339	$	(10)	$	277,143

As of March 31, 2024, the Company had 21 securities with a total fair market value of $193.9 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, 2024 and December 31, 2023. All securities held by the Company have a maturity date of one year or less. 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, 2024 and 2023.

Other Significant Agreements - Paragon Agreement (Details)
$ in Thousands

1 Months Ended

3 Months Ended

12 Months Ended

Nov. 30, 2023

USD ($)

Nov. 30, 2022

USD ($)

item

Mar. 31, 2024

USD ($)

Dec. 31, 2023

USD ($)

Sep. 30, 2023

USD ($)

Mar. 31, 2023

USD ($)

Dec. 31, 2023

USD ($)

Other Significant Agreements Paragon Option Agreement

Research and development

^[1]

$ 28,716

$ 8,455

Issued total common units (in shares) | shares

58,456,027

50,655,671

Option Agreement

Other Significant Agreements Paragon Option Agreement

Aggregate acquisition cost

$ 3,500

Paragon Therapeutics, Inc | Related party

Other Significant Agreements Paragon Option Agreement

Research and development

$ 6,500

$ 7,500

Paragon Therapeutics, Inc | Option Agreement

Other Significant Agreements Paragon Option Agreement

Payments due upon exercise of option

$ 0

Termination period of agreement

30 days

Period of material breach

30 days

Threshold number of days for termination upon failure to make payment and such failure persists even after the notice

30 days

Payment of non-refundable fees

2,000

Paragon Therapeutics, Inc | Option Agreement | Related party

Other Significant Agreements Paragon Option Agreement

Number of selected targets initially included under the agreement | item

Upfront cash amount paid

$ 1,300

Issued common units (in shares) | shares

1,250,000

Issued total common units (in shares) | shares

5,000,000

Aggregate fair value on grant date

$ 2,200

Non-refundable fee

$ 2,000

$ 500

Paragon Therapeutics, Inc | Option Agreement | Maximum | Related party

Other Significant Agreements Paragon Option Agreement

Issued total common units (in shares) | shares

3,750,000

Paragon Therapeutics, Inc | Paragon IL13 License Agreement

Other Significant Agreements Paragon Option Agreement

Expiration period of commercial sale

12 years

Termination period of agreement

60 days

Period of material breach

90 days

Threshold number of days for termination upon failure to make payment and such failure persists even after the notice

30 days

Paragon Therapeutics, Inc | Paragon IL13 License Agreement | Related party

Other Significant Agreements Paragon Option Agreement

Maximum amount of achievement of development and clinical mile stones

$ 3,000

Nomination fee paid

1,000

2,000

$ 1,000

$ 2,000

Milestone payment of trial payable

$ 2,000

[1]	Includes related-party amounts of $6,457 for the three months ended March 31, 2024, and $7,527 for the three months ended March 31, 2023.

CONDENSED CONSOLIDATED STATEMENT OF OPERATIONS - USD ($)
$ in Thousands

3 Months Ended

Mar. 31, 2024

Mar. 31, 2023

Operating expenses:

Research and development

^[1]

$ 28,716

$ 8,455

General and administrative

^[2]

9,465

4,203

Total operating expenses

38,181

12,658

Loss from operations

(38,181)

(12,658)

Other income, net:

Interest income, net

6,087

133

Total other income (expense), net

6,087

133

Net loss

$ (32,094)

$ (12,525)

Net loss per share, basic

$ (0.64)

$ (2.51)

Net loss per share, diluted

$ (0.64)

$ (2.51)

Weighted-average common shares outstanding, basic

50,189,808

5,000,000

Weighted-average common shares outstanding, diluted

50,189,808

5,000,000

[1]	Includes related-party amounts of $6,457 for the three months ended March 31, 2024, and $7,527 for the three months ended March 31, 2023.
[2]	No related-party amounts for the three months ended March 31, 2024, and $19 for the three months ended March 31, 2023.

Equity-Based Compensation

3 Months Ended

Mar. 31, 2024

Equity-Based Compensation

Equity-Based Compensation

12.Equity-Based Compensation

Incentive Units

Prior to the Reorganization, the Company periodically granted incentive units to employees, managers and executives, as well as to consultants and service providers of the Company. The incentive units represent a separate substantive class of members’ equity with defined rights. The incentive units represent profits interest in the increase in the value of the entity over a threshold value, or strike price, as determined at the time of grant. The strike price is established for tax compliance purposes related to Internal Revenue Service Revenue Procedure 93-27 and 2001-43 where the Company allocates equity value to separate classes of equity in a hypothetical liquidation transaction as of the date of grant. Each incentive unit issued includes a strike price determined by the Board of Managers. The strike price is based on an estimate of the amount a common unit would receive on the date of issuance of such incentive units in a hypothetical liquidation of the Company in which the Company sold its assets for their fair market value, satisfied its liabilities, and distributed the net proceeds to the holders of units in liquidation of the Company.

The Company accounts for equity-based compensation in accordance with ASC 718. In accordance with ASC 718, compensation cost is measured at estimated fair value and is included as compensation expense over the vesting period during which service is provided in exchange for the award. The service-based incentive unit grants generally vest over a four-year service period, with the first 25% vesting on the 12-month anniversary of the vesting start date and the remaining vesting in equal monthly installments over the following 36 months. The service-based and performance-based incentive unit grant, which the Company has one such award, vests in the same manner as the service-based award upon the achievement of the performance condition. The Company had one incentive unit grant which vested immediately upon issuance. The holders of vested incentive units are entitled to distributions and are not required to purchase or “exercise” their incentive units in order to receive such distributions. However, distributions to incentive unit holders began only after the cumulative amount distributed to common unit holders exceeds the strike price with respect to such incentive unit.

The Company determined that incentive units issued to employees, managers, executives, non-employees and service providers are equity-based service payments and, as such, the Company measures and recognizes the related compensation expense in a manner consistent with its accounting policy for equity-based awards.

The fair value of each incentive unit grant was estimated on the grant date using either an option pricing method (“OPM”), or a hybrid method, both of which used market approaches to estimate the Company’s enterprise value. The OPM treats common units, incentive units and preferred units as call options on the total equity value of a company, with exercise prices based on the value thresholds at which the allocation among the various holders of a company’s securities changes. Under this method, the incentive units have value only if the funds available for distribution to unitholders exceed the value of the preferred and common unit distribution preferences and the strike price with respect to such incentive unit at the time of the liquidity event. The hybrid method is a probability-weighted expected return method (“PWERM”), where the equity value is allocated in one or more of the scenarios using an OPM. The PWERM is a scenario-based methodology that estimates the fair value of each unit based upon an analysis of future values, assuming various outcomes. The incentive unit value is based on the probability-weighted value across the scenarios, considering the OPM to estimate the value within each scenario given the rights of each class of unit. A discount for lack of marketability of the incentive unit is then applied to arrive at an indication of fair value for the incentive unit.

The following assumptions were used in determining the fair value of incentive units granted during the period:


		THREE MONTHS ENDED
		MARCH 31,
		2023
Risk free interest rate		4.3%
Expected dividend yield		0.0%
Expected term (in years)		0.71-2.25
Expected volatility		77.0%

Restricted Common Stock

Concurrent with the Reorganization, all of the outstanding incentive units were exchanged into 3,469,546 shares of common stock, of which 2,779,358 were unvested restricted common stock. The following table provides a summary of the unvested restricted common stock award activity during the three months ended March 31, 2024:


		WEIGHTED-
		AVERAGE
	NUMBER OF	GRANT DATE FAIR
	SHARES	VALUE PER SHARE
Unvested restricted common stock as of December 31, 2023	2,316,902	$	5.31
Vested	(228,677)	$	4.12
Unvested restricted common stock as of March 31, 2024	2,088,225	$	5.44

The fair value of restricted stock vested during the three months ended March 31, 2024 was $0.9 million.

2023 Equity Incentive Plan

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 the date of the effectiveness of the registration statement for the IPO. 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, 2024, the number of shares of common stock reserved for issuance under the 2023 Plan is equal to 9,122,975 shares of common stock. The number of shares available for grant and issuance under the 2023 Plan will be 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,
		2024
Common stock fair value		$33.50 - $66.45
Risk free interest rate		3.9% - 4.3%
Expected dividend yield		0.0%
Expected term (in years)		6.25
Expected volatility		95.0% - 96.4%

The following table provides a summary of stock option activity under the 2023 Plan during the three months ended March 31, 2024:


				WEIGHTED-
		WEIGHTED-		AVERAGE		AGGREGATE
		AVERAGE		REMAINING		INTRINSIC
		EXERCISE		CONTRACTUAL TERM		VALUE
	OPTIONS	PRICE		(IN YEARS)		(IN THOUSANDS)
Outstanding as of December 31, 2023	2,506,017	$	21.49		9.80		16,154
Granted	110,259	$	38.53		—		—
Exercised	(1,047)	$	22.86		—		—
Forfeited	—	$	—		—		—
Outstanding as of March 31, 2024	2,615,229	$	22.21		9.61		115,694
Vested and expected to vest as of March 31, 2024	2,615,229	$	22.21		9.61		115,694
Exercisable as of March 31, 2024	99,955	$	22.93		9.38		4,350

The fair value of options vested during the three months ended March 31, 2024 was $1.8 million.

The following table provides a summary of the unvested restricted stock unit activity under the 2023 Plan during the three months ended March 31, 2024:


		WEIGHTED-
		AVERAGE
	NUMBER OF	GRANT DATE FAIR
	SHARES	VALUE PER SHARE
Unvested restricted stock units as of December 31, 2023	144,090	$	22.86
Vested	(8,988)		22.86
Unvested restricted stock units as of March 31, 2024	135,102	$	22.86

The fair value of restricted stock units vested during the three months ended March 31, 2024 was $0.2 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. The first purchase period commenced in January 2024. As of March 31, 2024, no shares have been issued under the ESPP and 962,390 shares remain available for issuance.

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



	THREE MONTHS		THREE MONTHS
	ENDED MARCH 31,		ENDED MARCH 31,
	2024		2023
Research and development expense	$	1,930	$	133
General and administrative expense		2,256		1,141
Total	$	4,186	$	1,274

As of March 31, 2024, the total unrecognized compensation expense related to the Company’s stock options, unvested restricted stock and ESPP was $55.5 million, which the Company expects to recognize over a weighted-average period of approximately 3.4 years.

In August 2023, the Board approved two option grants to the new Chairman of the Board, (1) to purchase 50,000 shares of the Company’s common stock under the 2023 Plan (“first option”), and (2) to purchase 100,000 shares of the Company’s common stock outside of the 2023 Plan (“second option”), in which the shares underlying both options will vest and become exercisable in equal monthly installments over a three-year period from August 2023. The second option is contingent upon approval of the shares underlying the award by the Company’s stockholders at the 2024 Annual Meeting of Stockholders and failure to obtain stockholder approval will result in the forfeiture of the award. Prior to receiving stockholder approval for the second option, neither a grant date nor a service inception date will occur, and no compensation cost is recognized for the award. Should stockholder approval be received at the 2024 Annual Meeting of Stockholders, a cumulative catch-up in equity-based compensation for the second option will be recognized on the date of stockholder approval.

Summary of Significant Accounting Policies

3 Months Ended

Mar. 31, 2024

Summary of Significant Accounting Policies

Summary of Significant Accounting Policies

2.Summary of Significant Accounting Policies

There have been no material changes to the significant accounting policies as disclosed in Note 2 to the Company consolidated financial statements for the year ended December 31, 2023 included in the Company’s Annual Report on Form 10-K filed with the SEC on March 5, 2024, except as noted below.

Basis of Presentation

Principles of Consolidation

Use of Estimates

Segments

Fair Value of Financial Instruments

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.

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.

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
Laboratory equipment		5 years

Preferred Units

Research and Development Expense

Income Taxes

Cash and Cash Equivalents

Marketable Securities

The Company classifies its available-for-sale securities as current assets on the condensed consolidated balance sheets as they mature within one year from the balance sheet date.

Leases

Equity-Based Compensation

Concentrations of Credit Risk and Significant Suppliers

Off-Balance Sheet Arrangements

As March 31, 2024 and December 31, 2023, the Company had no off-balance sheet risks such as foreign exchange contracts, option contracts or other foreign hedging arrangements.

Comprehensive Loss

Net Loss Per Share

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 485,457	$ 118,316
Marketable securities	330,739	277,143
Prepaid expenses and other current assets	4,412	2,950
Total current assets	820,608	398,409
Property and equipment, net	699	377
Right-of-use asset, net	1,951	2,217
Other non-current assets	401	401
Total assets	823,659	401,404
Current liabilities:
Accounts payable	4,302	2,143
Lease liability	1,141	1,101
Accrued expenses	16,108	17,314
Total current liabilities	21,551	20,558
Long-term liabilities:
Lease liability, net of current	630	933
Total liabilities	22,181	21,491
Stockholders' equity/members' deficit:
Common Stock; $0.00001 par value, 400,000,000 authorized, 58,456,027 issued and 56,367,802 outstanding as of March 31, 2024; 400,000,000 authorized, 50,655,671 issued and 48,338,769 outstanding as of December 31, 2023	1
Additional paid-in capital	957,518	503,354
Accumulated other comprehensive (loss) income	(177)	329
Accumulated deficit	(155,864)	(123,770)
Total stockholders' equity	801,478	379,913
Total liabilities and stockholders' equity	$ 823,659	$ 401,404

Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2024	May 06, 2024
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2024
Document Transition Report	false
Entity File Number	001-41740
Entity Registrant Name	Apogee Therapeutics, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	93-4958665
Entity Address, Address Line One	221 Crescent St.
Entity Address, Address Line Two	Building 17
Entity Address, Address Line Three	Suite 102b
Entity Address, City or Town	Waltham
Entity Address State Or Province	MA
Entity Address, Postal Zip Code	02453
City Area Code	650
Local Phone Number	394-5230
Title of 12(b) Security	Common Stock, par value $0.00001 per share
Trading Symbol	APGE
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Central Index Key	0001974640
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q1
Amendment Flag	false
Voting Common Stock
Entity Common Stock, Shares Outstanding		44,969,385
Nonvoting Common Stock
Entity Common Stock, Shares Outstanding		13,486,642

Net Loss Per Share - Basic and diluted net loss per unit attributable to common unitholders (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Numerator:
Net loss	$ (32,094)	$ (12,525)
Net loss attributable to common stockholders, basic	(32,094)	(12,525)
Net loss attributable to common stockholders, diluted	$ (32,094)	$ (12,525)
Denominator:
Weighted average shares of common stock outstanding, basic	50,189,808	5,000,000
Weighted average shares of common stock outstanding, diluted	50,189,808	5,000,000
Net loss per share attributable to common stockholders, basic	$ (0.64)	$ (2.51)
Net loss per share attributable to common stockholders, diluted	$ (0.64)	$ (2.51)

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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+ Details

- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

+ Details

- Definition

Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities; of income (loss) available to common shareholders.

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Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities, and addition from assumption of issuance of common shares for dilutive potential common shares; of income (loss) available to common shareholders.

+ References + Details

Equity-Based Compensation - Determining fair value of incentive units (Details) - Incentive Units	3 Months Ended
	Mar. 31, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Risk free interest rate	4.30%
Expected dividend yield	0.00%
Expected volatility	77.00%
Minimum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Expected term	8 months 15 days
Maximum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Expected term	2 years 3 months

- Definition

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

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+ Details

Marketable Securities (Tables)

3 Months Ended

Mar. 31, 2024

Marketable Securities

Schedule of Company's investing portfolio

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


	AS OF MARCH 31, 2024
			UNREALIZED
	COST		GAINS		LOSSES		FAIR VALUE
Marketable securities:
U.S. treasury securities	$	151,251	$	13	$	(59)	$	151,205
Debt securities issued by U.S. government agencies		179,665		24		(155)		179,534
	$	330,916	$	37	$	(214)	$	330,739


	AS OF DECEMBER 31, 2023
			UNREALIZED
	COST		GAINS		LOSSES		FAIR VALUE
Marketable securities:
U.S. treasury securities	$	123,836	$	140	$	(2)	$	123,974
Debt securities issued by U.S. government agencies		152,978		199		(8)		153,169
	$	276,814	$	339	$	(10)	$	277,143

- Definition

Tabular disclosure of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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+ Details

Common Stock - Additional Information (Details) - $ / shares			3 Months Ended		12 Months Ended
	Mar. 12, 2024	Jul. 18, 2023	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Common Stock
Preferred Units, units converted		24,987,750
Common stock, shares authorized		400,000,000	400,000,000		400,000,000
Common stock, par value		$ 0.00001	$ 0.00001		$ 0.00001
Common stock, shares, issued			58,456,027		50,655,671
Common stock, shares outstanding			56,367,802		48,338,769
Antidilutive units			4,846,619	76,140,113
Voting Common Stock
Common Stock
Common stock, shares, issued			44,969,385		37,169,029
Nonvoting Common Stock
Common Stock
Common stock, shares, issued			13,486,642		13,486,642
Unvested restricted common stock
Common Stock
Antidilutive units			2,088,225		2,316,902
IPO
Common Stock
Shares issued	7,790,321	20,297,500
Overallotment option
Common Stock
Shares issued	1,016,128	2,647,500	7,790,321

Equity-Based Compensation - Additional Information (Details) $ in Thousands		1 Months Ended		3 Months Ended
	Feb. 04, 2022 shares	Aug. 31, 2023 USD ($) Option shares	Jul. 31, 2023	Mar. 31, 2024 USD ($) shares	Mar. 31, 2023 USD ($)
Equity-Based Compensation
Vesting period (in years)		3 years
Shares converted	3,469,546
Granted				110,259
Number of stock option grants \| Option		2
Equity-based compensation expense \| $		$ 0		$ 4,186	$ 1,274
Granted (in shares)		100,000
Incentive Units
Equity-Based Compensation
Vesting period (in years)				4 years
Incentive Units \| Tranche One [Member]
Equity-Based Compensation
Vesting period (in years)				12 months
Vesting (as percentage)				25.00%
Incentive Units \| Tranche Two [Member]
Equity-Based Compensation
Vesting period (in years)				36 months
Vesting (as percentage)				75.00%
Unvested restricted common stock
Equity-Based Compensation
Exchange of incentive units	2,779,358
2023 Equity Incentive Plan
Equity-Based Compensation
Common stock reserved for issuance				9,122,975
Increase in shares available for grand (as percentage)			5.00%
Granted		50,000
2023 Employee Stock Purchase Plan
Equity-Based Compensation
Common stock reserved for issuance				962,390
Unrecognized compensation expense \| $				$ 55,500
Share based compensation recognition period				3 years 4 months 24 days
Granted (in shares)				0
Maximum percentage of eligible employees contribution			15.00%
Purchase Period			6 months
Purchase price percentage			85.00%

Other Significant Agreements

3 Months Ended

Mar. 31, 2024

Other Significant Agreements

Other Significant Agreements

8.Other Significant Agreements

Paragon Option and License Agreements

For the three months ended March 31, 2024 and 2023, the Company recognized $6.5 million and $7.5 million, respectively, of research and development expense in connection with services provided by Paragon under the Option and License Agreements.

Option Agreements

In February 2022, the Company entered into 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 focus 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 and Paragon agreed 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 each Research Program is exercisable at its 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.

Unless terminated earlier, the 2022 Option Agreement 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 “2022 Term”). Upon the expiration of the 2022 Term for all then-existing Research Programs, under the 2022 Option Agreement, the 2022 Option Agreement will automatically expire in its entirety. The Company may terminate the 2022 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 the 2022 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.

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 Tranche Options of the Series A Preferred Unit financing (see Note 10). Through March 31, 2024, the Company had issued a total of 5,000,000 common units to Paragon with an aggregate fair value of $2.2 million on the grant date. 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. The Company expenses the service fees as the associated costs are incurred when the underlying services are rendered. Such amounts are classified within research and development expenses in the accompanying condensed consolidated statement of operations and comprehensive loss.

The Company concluded that the rights obtained under the 2022 Option Agreement represent an asset acquisition whereby the underlying assets comprise in-process research and development assets with no alternative future use. The 2022 Option Agreement did not qualify as a business combination because substantially all of the fair value of the assets acquired was concentrated in the exclusive license options, which represent a group of similar identifiable assets. Therefore, the aggregate acquisition cost of $3.5 million, related to the upfront cash and equity payments, was recognized as acquired in-process research and development expense, which is reported as a component of research and development expense during the period from February 4, 2022 (inception) to December 31, 2022. Amounts paid as on-going development cost reimbursements associated with services being rendered under the related Research Programs is recognized as research and development expense when incurred.

In November 2023, the Company entered the 2023 Option Agreement. 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 undisclosed target. 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 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 2023 Option Agreement, the parties may initiate Research Programs. Each Research Program is 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 outlines the services that will be performed commencing at inception of the arrangement related to the undisclosed target. The Company’s exclusive option with respect to each Research Program is exercisable at its 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. There is no payment due upon exercise of an Option pursuant to the 2023 Option Agreement. Following entry into the 2023 Option Agreement, the Company and Paragon will negotiate a form of License Agreement to be entered into in the event that the Company exercises its exclusive option with respect to each Research Program, which License Agreement will include certain pre-agreed economic and other business terms.

Unless terminated earlier, the 2023 Option Agreement 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 “2023 Term”). Upon the expiration of the 2023 Term for all then-existing Research Programs, under the 2023 Option Agreement, the 2023 Option Agreement will automatically expire in its entirety. The Company may terminate the 2023 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 the 2023 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.

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 undisclosed target. As such, the Company made a one-time non-refundable payment of $2.0 million to Paragon in the first quarter of 2024.

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, and collectively with the IL-13 License Agreement, the “License Agreements”). Under the terms of each 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 target 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 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.

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. 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 APG777 and incurred a

milestone payment of $2.0 million to Paragon in the third 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 first dosing of a human patient in a Phase 1 trial of APG808 in healthy volunteers and made a milestone payment of $2.0 million to Paragon in the first 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 License Agreements, and Paragon has a similar obligation to pay royalties to the Company with respect to the 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.

The Company concluded that each of the License Agreements constitutes an asset acquisition of in-process research and development assets with no alternative future use. Each of the arrangements did not qualify as a business combination because substantially all of the fair value of the assets acquired was concentrated in the license which comprises a single identifiable asset. Therefore, the aggregate acquisition cost for each license was recognized as research and development expense.

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 APG777, APG808 and APG990 programs, as well as the Company’s other programs, 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 busy 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, 2024, the Company recognized $4.4 million of research and development expense in connection with the WuXi Biologics MSA subsequent to novation.

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’s 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 a component of the APG777 and APG808 programs.

In consideration for the license, the Company agreed to pay 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, it 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.

The Cell Line License Agreement will continue indefinitely unless terminated (i) by the Company upon six months’ prior written notice and its 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.

CONDENSED CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Series A Preferred Units	Series B Preferred Units	Common Units	Incentive Units	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income	Total
Beginning balance at Dec. 31, 2022	$ 28,971	$ 148,496
Beginning balance (in shares) at Dec. 31, 2022	20,000,000	45,089,212
Ending balance at Mar. 31, 2023	$ 28,971	$ 148,496
Ending balance (in shares) at Mar. 31, 2023	20,000,000	45,089,212							65,089,212
Beginning balance at Dec. 31, 2022			$ 2,251	$ 2,142			$ (39,785)		$ (35,392)
Beginning balance (in shares) at Dec. 31, 2022			5,000,000	1,625,086
MEMBERS' DEFICIT
Equity Based Compensation Expense				$ 1,274					1,274
Net loss							(12,525)		(12,525)
Ending balance at Mar. 31, 2023			$ 2,251	$ 3,416			(52,310)		(46,643)
Ending balance (in shares) at Mar. 31, 2023			5,000,000	1,625,086
Beginning balance at Dec. 31, 2023						$ 503,354	(123,770)	$ 329	379,913
Beginning balance (in shares) at Dec. 31, 2023					48,338,769
MEMBERS' DEFICIT
Common stock issued, net of issuance costs of $32,985					$ 1	449,954			449,955
Common stock issued, net of issuance costs of $32,985 (in shares)					7,790,321
Vesting of restricted stock (in shares)					237,665
Issuance of common stock upon exercise of stock options						24			$ 24
Issuance of common stock upon exercise of stock options (in shares)					1,047				1,047
Equity Based Compensation Expense						4,186			$ 4,186
Change in unrealized loss on marketable securities, net of tax								(506)	(506)
Net loss							(32,094)		(32,094)
Ending balance at Mar. 31, 2024					$ 1	$ 957,518	$ (155,864)	$ (177)	$ 801,478
Ending balance (in shares) at Mar. 31, 2024					56,367,802

CONDENSED CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY (Parenthetical) $ in Thousands	3 Months Ended
	Mar. 31, 2024 USD ($)
CONDENSED CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY
Stock issuance costs	$ 33,045

Prepaids and Other Assets - Restricted cash (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Prepaids and Other Assets
Restricted cash	$ 0.3	$ 0.3

Equity-Based Compensation - Summary of Company's Unvested Restricted Common Stock Award Activity (Details) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2024 USD ($) $ / shares shares
WEIGHTED-AVERAGE GRANT DATE FAIR VALUE PER SHARE
Fair value units vested \| $	$ 1.8
Unvested restricted common stock
NUMBER OF SHARES
Beginning balance \| shares	2,316,902
Vested \| shares	(228,677)
Ending balance \| shares	2,088,225
WEIGHTED-AVERAGE GRANT DATE FAIR VALUE PER SHARE
Beginning balance (in dollars per share) \| $ / shares	$ 5.31
Vested (in dollars per share) \| $ / shares	4.12
Ending balance (in dollars per share) \| $ / shares	$ 5.44
Fair value units vested \| $	$ 0.9

Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Accrued Expenses
Accrued external research and development expenses	$ 4,946	$ 6,685
Accrued manufacturing expenses	6,734	9,219
Accrued other	2,136	1,243
Accrued employee compensation	2,292	167
Total	$ 16,108	$ 17,314

Subsequent Events (Details) $ in Millions	2 Months Ended
Subsequent Events (Details) $ in Millions	May 31, 2024 USD ($)
Subsequent Events \| Paragon Therapeutics, Inc \| Related party \| OX40L License Agreement
Subsequent Events
Non-refundable payments	$ 1.0

Net Loss Per Share - Potential common units excluded from calculation of diluted net loss per unit attributable to common unitholders (Details) - shares	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Net Loss Per Share
Antidilutive units	4,846,619	76,140,113
Series A Preferred Units
Net Loss Per Share
Antidilutive units		20,000,000
Series B Preferred Units
Net Loss Per Share
Antidilutive units		45,089,212
Vested incentive units
Net Loss Per Share
Antidilutive units		1,625,086
Unvested incentive units
Net Loss Per Share
Antidilutive units		9,425,815
Stock options
Net Loss Per Share
Antidilutive units	2,615,229
Unvested restricted common stock
Net Loss Per Share
Antidilutive units	2,088,225
Unvested restricted stock units
Net Loss Per Share
Antidilutive units	135,102
Potential shares issuable under the ESPP
Net Loss Per Share
Antidilutive units	8,063

Operating Leases (Details) - USD ($) $ in Thousands	3 Months Ended
Operating Leases (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Operating Leases
Lease liability, current	$ 1,141	$ 1,101
Lease liability, Non-current	$ 630	$ 933
Operating lease, remaining lease term	1 year 8 months 12 days
Incremental borrowing rate used to determine the operating lease liabilities	10.00%
Lease expense	$ 266

Summary of Significant Accounting Policies (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024 USD ($) segment	Dec. 31, 2023 USD ($)
Summary of Significant Accounting Policies
Number of Operating Segments	1
Number of Reportable Segments	1
Concentration Risk, Credit Risk, Financial Instrument, Maximum Exposure \| $	$ 0	$ 0

Prepaids and Other Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Prepaids and Other Assets
Prepaid expenses	$ 1,692	$ 1,736
Other current assets	2,720	1,214
Total	$ 4,412	$ 2,950

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Mar. 31, 2024
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Property and Equipment, net (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Property and Equipment, net
Property and equipment, net	$ 699	$ 377
Laboratory equipment
Property and Equipment, net
Property and equipment, net	$ 700	$ 400

Marketable Securities - Schedule of Company's investing portfolio (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Marketable Securities
COST	$ 330,916	$ 276,814
UNREALIZED GAINS	37	339
UNREALIZED LOSSES	(214)	(10)
FAIR VALUE	330,739	277,143
U.S. treasury securities \| Marketable securities
Marketable Securities
COST	151,251	123,836
UNREALIZED GAINS	13	140
UNREALIZED LOSSES	(59)	(2)
FAIR VALUE	151,205	123,974
Debt securities issued by U.S. government agencies \| Marketable securities
Marketable Securities
COST	179,665	152,978
UNREALIZED GAINS	24	199
UNREALIZED LOSSES	(155)	(8)
FAIR VALUE	$ 179,534	$ 153,169

Summary of Significant Accounting Policies - Property and Equipment (Details)	Mar. 31, 2024
Laboratory equipment
Property and Equipment, net
Property and equipment useful Life	5 years

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2024	Dec. 31, 2023	Jul. 18, 2023
CONDENSED CONSOLIDATED BALANCE SHEETS
Common stock, par value	$ 0.00001	$ 0.00001	$ 0.00001
Common stock, shares authorized	400,000,000	400,000,000	400,000,000
Common stock, shares, issued	58,456,027	50,655,671
Common stock, shares outstanding	56,367,802	48,338,769

Marketable Securities (Details) $ in Thousands	Mar. 31, 2024 USD ($) security	Dec. 31, 2023 USD ($)
Marketable Securities
Number of securities in unrealized loss position, less than 12 months \| security	21
Value of securities in unrealized loss position, less than 12 months	$ 193,900
Allowance for credit loss	$ 0	$ 0