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

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

Overview

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

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

Zumilokibart (APG777) – anti-IL13 antibody

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

Phase 1 Trial in Healthy Volunteers

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

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

APEX Phase 2 Trial for Patients with AD

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

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

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

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

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

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

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

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

Phase 1b Trial in Patients with Asthma

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

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

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

Expansion Opportunities in Other Indications

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

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

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

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

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

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

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

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

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

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

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

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

APG808 – anti-IL4Rα antibody

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

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

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

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

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Recent Developments

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

Equity Offerings

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

ATM Facility

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

Net Loss

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

Macroeconomic Conditions

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

Collaboration, License and Service Agreements

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

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Overview of Financial Results

Revenue

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

Operating Expenses

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

Research and Development

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

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

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

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

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

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

General and Administrative

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

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

Other Income (Expense), Net

Interest Income

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

Income Taxes

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

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

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

Results of Operations

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

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

Results of Operations

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

Research and Development Expense

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

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

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

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

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

General and Administrative Expense

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