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 regarding the proposed Merger, including the timing, completion and anticipated benefits of the Merger and the satisfaction of the conditions to closing, and 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), APG531 and APG808 (each a “program” or “product candidate”). With five 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 – 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. 28 Table of Contents 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. 29 Table of Contents 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 vIGA0/1, 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. In May 2026, we announced positive 16-week induction dose optimization results from the Part B portion of the APEX Phase 2 clinical trial of zumilokibart in patients with moderate-to-severe AD. The Part B portion of the trial enrolled 346 adult patients who were randomized 1:1:1:1 to receive high-, mid- or low-dose zumilokibart or placebo. The primary endpoint for the Part B portion of the trial was the proportion of patients who achieved at least a 75% reduction in EASI-75 at Week 16. Secondary endpoints included vIGA 0/1, EASI-90, Itch NRS, EASI-100 and very low disease activity (“vLDA”), defined as EASI-90 plus I-NRS 0/1, at Week 16. The Part B trial met its primary endpoint, with all three zumilokibart dose arms demonstrating statistically significant improvements in EASI-75 compared to placebo at Week 16. EASI-75 was achieved by 61.6% of patients in the high-dose arm, 65.9% of patients in the mid-dose arm and 50.5% of patients in the low-dose arm, compared to 23.4% of patients in the placebo arm. The planned Phase 3 dose, corresponding to the mid-dose arm, also met key secondary endpoints at Week 16, with 46.0% of patients achieving vIGA 0/1 compared to 10.9% in the placebo arm, 47.4% of patients achieving EASI-90 compared to 9.3% in the placebo arm, 50.5% of patients achieving an I-NRS ≥4 reduction from baseline compared to 13.9% in the placebo arm, 16.5% of patients achieving EASI-100 compared to 3.4% in the placebo arm and 20.6% of patients achieving vLDA compared to 4.5% in the placebo arm. Zumilokibart was well tolerated in Part B, with a safety profile generally consistent with other agents in the class. The most common TEAEs in patients treated with zumilokibart were nasopharyngitis, headache and noninfective conjunctivitis. For the planned Phase 3 dose, corresponding to the mid-dose arm, the pooled conjunctivitis rate, including all conjunctivitis preferred terms, was 10.6%, compared to 15.1% for the low-dose arm and 20.7% for the high-dose arm. Based on results from the APEX clinical program, we plan to initiate Phase 3 trials of zumilokibart for moderate-to-severe AD with the mid-dose in the second half of 2026. Anticipated Program Milestones for Zumilokibart for the Treatment of AD Based on results from the APEX clinical program, we plan to initiate Phase 3 trials of zumilokibart for moderate-to-severe AD (the “ADventure trials”) with the mid-dose in the second half of 2026. The ADventure 1 and ADventure 2 trials are randomized, placebo-controlled, replicate Phase 3 monotherapy trials evaluating zumilokibart in patients with moderate-to-severe AD (EASI ≥16, vIGA ≥3, BSA ≥10%). Each study is expected to enroll approximately 400 patients and includes a 16-week induction period followed by maintenance through Week 52. In maintenance, patients will receive dosing every three or six months. The co-primary endpoint is EASI-75 and IGA 0/1 at Week 16, with additional assessment at Week 52. We anticipate the ADventure 1 and ADventure 2 monotherapy data readouts in the first half of 2028. The ADventure TCS Phase 3 trial will evaluate zumilokibart in combination with background topical corticosteroids (“TCS”) in patients with moderate-to-severe AD (EASI ≥16, vIGA ≥3, BSA ≥10%). The randomized, placebo-controlled study is expected to enroll approximately 400 patients and includes a 16-week induction period and maintenance through Week 52. The co-primary endpoint is EASI-75 and IGA 0/1 at Week 16, with longer-term outcomes assessed at Week 52. We anticipate the ADventure TCS combination data readout in the second half of 2028. Apogee also expects Phase 2 APEX Part B 52-week maintenance data in the first half of 2027, Phase 2 APEX Part A 2-year follow-up data in the second half of 2027 and the potential launch of zumilokibart for the treatment of AD in 2029, pending regulatory interactions. Phase 1b Trial in Patients with Asthma In April 2025, we initiated a Phase 1b trial of zumilokibart 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 720mg 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. 30 Table of Contents 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 initiating the ASPIRE Phase 2b asthma trial in the first half of 2027. 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 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 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 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. We anticipate the Phase 1b trial of APG279 against DUPIXENT to readout in the second half of 2026. 31 Table of Contents APG273 – Combination of zumilokibart 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 1,000mg, 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 the second half of 2026 to support advancement into future combination trials in asthma and COPD. APG531 In June 2026, we also announced that we entered into an antibody discovery agreement with Paragon (the “2026 Option Agreement”) pursuant to which Paragon agrees to generate and characterize monospecific antibody candidates directed to interleukin 31 receptor (IL-31R). Contemporaneously with the execution of the 2026 Option Agreement, we entered into a license agreement with Paragon (the “IL-31R License Agreement”) pursuant to which Paragon granted to us an exclusive, worldwide, royalty-bearing, sublicensable right and license with respect to certain information, patent rights and sequence information related to antibodies discovered under the 2026 Option Agreement and directed at the IL-31R target to use, make, sell, import, export and otherwise exploit the antibodies directed at the IL-31R target. For additional information on the 2026 Option Agreement and IL-31R License Agreement, see the section titled “Notes to Consolidated Financial Statements—Other Significant Agreements” included elsewhere in this Report. We anticipate announcing plans for the APG531 program in the first half of 2027. 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. 32 Table of Contents Recent Developments The following summarizes key business developments for the six months ended June 30, 2026, excluding program updates discussed in the “Overview” section above. Merger Agreement On June 18, 2026, we entered into the Merger Agreement with Parent, Merger Sub and, solely for the limited purposes set forth therein, AbbVie. Under the terms of the Merger Agreement and in accordance with the General Corporation Law of the State of Delaware (“DGCL”), if the Merger is completed, Merger Sub will merge with and into us, and we will continue as the surviving corporation as a wholly owned subsidiary of Parent. In addition, all shares of our common stock outstanding immediately prior to closing (other than Cancelled Shares and Dissenting Shares (as defined in the Merger Agreement)) will be cancelled and converted into the right to receive $135.11 per share in cash, without interest and subject to any applicable withholding taxes. The completion of the pending Merger is conditioned upon (i) the adoption of the Merger Agreement and approval of the Merger by the holders of at least a majority of the outstanding shares of our voting common stock, (ii) for so long as at least 6,061,821 shares of our non-voting common stock remain issued and outstanding, the adoption of the Merger Agreement and approval of the Merger by at least a majority of the outstanding shares of our non-voting common stock, (iii) the expiration or earlier termination of any waiting period (and any extension thereof) under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended (the “HSR Act”), and the filings specified on the Company Disclosure Schedule to the Merger Agreement (which will also include filings to be made to the U.K. Competition and Markets Authority under the U.K. Enterprise Act of 2002 or the European Commission under Article 22 of the EU Merger Regulation, in each case, if such authority indicates in writing to AbbVie that it has decided to formally investigate the Merger or has received a referral request, as applicable) and any voluntary commitment or agreement with the U.S. Federal Trade Commission (“FTC”), U.S. Department of Justice (“DOJ”) or any other governmental body not to consummate the Merger, (iv) the absence of legal restraints preventing or otherwise making illegal the consummation of the Merger, (v) the accuracy of representations and warranties that we made and compliance by us with covenants contained in the Merger Agreement, subject to qualifications, (vi) there not having been a “Material Adverse Effect” (as defined in the Merger Agreement) with respect to us since the date of the Merger Agreement that is continuing, and (vii) other customary conditions. As previously disclosed in the definitive proxy statement filed on July 13, 2026 (the “Proxy Statement”), we and Parent each filed a notification of the proposed Merger with the FTC and DOJ under the HSR Act on July 6, 2026. On August 5, 2026, the applicable waiting period under the HSR Act expired. The expiration of the waiting period under the HSR Act satisfies one of the conditions to the completion of the Merger. Also as previously disclosed in the Proxy Statement, on July 7, 2026, Parent filed a notification under the German Act against Restraints of Competition 1957, as amended, with the German Federal Cartel Office (the “FCO”). As disclosed in the definitive additional materials filed on August 3, 2026, which amended and supplemented the Proxy Statement (the “Proxy Supplement”), Parent obtained from the FCO unconditional clearance for the Merger in Germany. In addition, as previously disclosed in the Proxy Statement, on July 7, 2026, Parent filed a notification under the Austrian Cartel Act 2005, as amended, with the Austrian Federal Competition Authority, for which the Phase 1 statutory review period expired on August 4, 2026. Accordingly, the closing conditions relating to the receipt of Regulatory Approvals with respect to the German Act against Restraints of Competition 1957, as amended, and the Austrian Cartel Act 2005, as amended, have been satisfied. As previously disclosed in the Proxy Supplement, on July 27, 2026, Parent also filed a notification under the Australian Competition and Consumer Act 2010, as amended, with the Australian Competition and Consumer Commission (the “ACCC”), for which the Phase 1 statutory review period will expire on September 7, 2026, unless such period is terminated earlier by the ACCC. Completion of the Merger remains subject to the satisfaction or waiver of other customary closing conditions described in the Merger Agreement, including the receipt of any clearance, consent or affirmative approval applicable to the filings specified on the Company Disclosure Schedule to the Merger Agreement. The parties expect the Merger to close in the third quarter of 2026. Following completion of the Merger, our common stock will no longer be publicly listed. The Merger Agreement contains termination rights for us and Parent. If the Merger Agreement is terminated under specified circumstances, we will be required to pay Parent a fee of $381,273,716. 33 Table of Contents Revenue Participation Right Financing On May 26, 2026, we entered into a revenue participation right purchase and sale agreement (the “Revenue Share Agreement”) with Annapurna Aggregator L.P., an affiliate of funds managed by Blackstone Life Sciences (“BXLS”). Pursuant to the Revenue Share Agreement, in exchange for an upfront payment of $100.0 million (the “Tranche 1 Funding”), BXLS purchased from us the right to receive tiered revenue share payments (the “Revenue Share Payments”) with respect to annual worldwide net product sales (“Net Sales”) of zumilokibart. In addition, under the Revenue Share Agreement: i.BXLS will purchase additional Revenue Share Payments from us in exchange for a payment of $100.0 million (the “Tranche 2 Funding”), upon the occurrence of full enrollment of patients in both of our planned registrational monotherapy Phase 3 clinical trials of zumilokibart in patients with AD, coded by us as APG777-301 and APG777-302 (the “Zumilokibart Phase 3 Clinical Trials”); ii.BXLS will purchase additional Revenue Share Payments from us in exchange for a payment of $200.0 million (the “Tranche 3 Funding”), upon the occurrence of positive data readouts from the Zumilokibart Phase 3 Clinical Trials meeting the success criteria set forth in the Revenue Share Agreement; and iii.BXLS will purchase additional Revenue Share Payments from us in exchange for a payment (the “Tranche 4 Funding”) of, at our election, between $250.0 million and up to $400.0 million (“Tranche 4 Maximum Purchase Price”), upon zumilokibart’s receipt of marketing approval from the U.S. Food and Drug Administration for the treatment of AD on or prior to December 31, 2030 (the “Tranche 4 Trigger”). The Revenue Share Payments are based on tiered percentage rates of aggregate annual Net Sales of zumilokibart (“Annual Aggregate Product Net Sales”). Under the Revenue Share Agreement, the revenue percentage payable to BXLS is the sum of (a) the base revenue percentage (the “Base Revenue Percentage”) and (b) the tranche 4 revenue percentage (the “Tranche 4 Revenue Percentage” and, together with the Base Revenue Percentage, the “Revenue Percentages”), which applies only from and after the Tranche 4 Funding. The table below summarizes the Revenue Percentages payable to BXLS, based on the tiers of Annual Aggregate Product Net Sales. The Base Revenue Percentage shown reflects the rate applicable after receipt of the Tranche 1 Funding; this rate would double upon receipt of the Tranche 2 Funding, and double again upon receipt of the Tranche 3 Funding. The Tranche 4 Revenue Percentage is subject to proportional adjustment if the Tranche 4 Funding is less than the Tranche 4 Maximum Purchase Price: Annual Aggregate Product Net Sales Base Revenue Percentage Tranche 4 Revenue Percentage Maximum Revenue Percentage Up to and including $5 billion (“Tier 1”) 0.9375% 2.50% 3.4375% In excess of $5 billion but less than or equal to $8 billion 0.25% 0.00% 0.25% The Tranche 4 Revenue Percentage is subject to a cap of $1.0 billion in aggregate Tranche 4-related Revenue Share Payments to BXLS, after which the Tranche 4 Revenue Percentage for Tier 1 decreases to 0.00%. The Revenue Share Payments will be payable during a term commencing on the date of the first commercial sale of zumilokibart and ending on the fifteenth (15th) anniversary of the date of receipt of marketing approval for zumilokibart. If the Company consummates a change of control with a third party, the Company will be required to pay a certain specified amount to BXLS and would also receive credits against future Revenue Share Payments otherwise payable to BXLS following the consummation of the change of control. In the alternative, at any time following execution of a definitive agreement for a change of control, we (or the surviving entity) may elect, in lieu of the required payment described above, to pay BXLS a specified amount calculated under the Revenue Share Agreement to buy down a portion of future Revenue Share Payments (each, a "Buy-Back Option"). If we exercise a Buy-Back Option, the Revenue Percentage will be adjusted downward in accordance with the Revenue Share Agreement, and if the Buy-Back Option is exercised prior to the Tranche 4 Trigger, BXLS will no longer be obligated to pay the Tranche 4 Funding, and in such case the Tranche 4 Revenue Percentages across all tiers will be 0.00%. Under the Revenue Share Agreement, for the purposes of providing additional assurance to BXLS, including in the event of a recharacterization, we have granted BXLS a backup security interest in, among other things, the revenue participation right, the Revenue Share Payments, and our intellectual property and other product rights related to zumilokibart. This backup security interest will terminate upon the later of (a) a change of control with a permitted transferee and (b) BXLS’s receipt of the applicable change of control payment. We and BXLS also agree to negotiate in good faith a debt financing of up to $500.0 million upon mutual agreement. The Revenue Share Agreement contains customary representations, warranties and indemnities of us and BXLS, and customary covenants on our part. 34 Table of Contents 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 six months ended June 30, 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, which sales took place during the three months ended March 31, 2026. No shares were sold under the ATM Facility during the three months ended June 30, 2026. 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 $160.0 million for the six months ended June 30, 2026. As of June 30, 2026, we had an accumulated deficit of $721.7 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. 35 Table of Contents Overview of Financial Results Revenue We have not generated any revenue from product sales and do not expect to generate any revenue from the sale of products for several years, if at all. If our development efforts for our programs are successful and result in regulatory approval or collaboration or license agreements with third parties, we may generate revenue in the future from product sales or payments from collaboration or license agreements that we may enter into with third parties, or any combination thereof. Operating Expenses Our operating expenses consist of (i) research and development expenses and (ii) general and administrative expenses. Research and Development Research and development expenses consist primarily of costs incurred in connection with the development and research of our programs. These expenses include: •the cost of developing and validating our manufacturing process for use in our preclinical studies and current and future clinical trials; •expenses incurred in connection with continuing our current research programs and preclinical development of any programs we may identify, including under agreements with third parties, such as consultants and contractors; •costs of funding research performed by third parties, including Paragon, that conduct research and development and preclinical or clinical activities on our behalf; •the cost to acquire in-process research and development, with no alternative future use associated with asset acquisitions, such as the Option Agreements, and License Agreements; •expenses incurred under agreements with clinical trial sites and clinical research organizations (“CROs”) that conduct research and development activities on our behalf, including clinical trial execution, project management, data management and related outsourced services; •costs related to production of clinical supplies and preclinical materials, including fees paid to contract manufacturers; and •personnel-related expenses, including salaries, bonuses and equity-based compensation expense. We measure and recognize asset acquisitions or licenses to intellectual property that are not deemed to be business combinations based on the cost to acquire or license the asset or group of assets, which includes transaction costs. In an asset acquisition or license to intellectual property, the cost allocated to acquired in-process research and development, with no alternative future use is recognized as research and development expense on the acquisition date. We expense research and development costs as incurred. Non-refundable advance payments that we make for goods or services to be received in the future for use in research and development activities are recorded as prepaid expenses. The prepaid amounts are expensed as the related goods are delivered or the services are performed, or when it is no longer expected that the goods will be delivered or the services rendered. Our primary focus since inception has been the identification and development of our pipeline programs. Our research and development costs primarily consist of external costs, including CRO fees and fees paid to Paragon under the Option Agreements and the License Agreements. We do not separately track or segregate the amount of costs incurred under the Option Agreements due to the early-stage and discovery nature of the services. We do not allocate personnel-related costs by program because these resources are used and these costs are deployed across multiple programs under development, and, as such, are not separately classified. We expect that our research and development expenses will increase substantially for the foreseeable future as we continue to invest in research and development activities for our programs, and any potential future programs, including investments in clinical trials and manufacturing. The success of programs we may identify and develop will depend on many factors, including the following: •timely and successful completion of preclinical studies; •effective Investigational New Drug applications (“INDs”) or comparable foreign applications that allow commencement of our planned clinical trials or future clinical trials for any programs we may develop; 36 Table of Contents •successful enrollment and completion of clinical trials; •positive results from our future clinical trials that support a finding of safety and effectiveness, acceptable PK profile, and an acceptable risk-benefit profile in the intended populations; •receipt of marketing approvals from applicable regulatory authorities; •establishment of arrangements through our own facilities or with third-party manufacturers for clinical supply and, where applicable, commercial manufacturing capabilities; •establishment, maintenance, defense and enforcement of patent, trademark, trade secret and other intellectual property protection or regulatory exclusivity for any products we may develop; and •maintenance of a continued acceptable safety, tolerability and efficacy profile of any programs we may develop following approval. Any changes in the outcome of any of these variables with respect to the development of programs that we may identify could mean a significant change in the costs and timing associated with the development of such programs. For example, if the 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 Expenses 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. Merger Transaction Merger transaction expenses represent costs incurred in connection with the Merger Agreement discussed above. These costs primarily consist of legal and SEC-related fees. 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. Interest Expense Interest expense consists of interest accrued on our revenue share liability, which arises from our Revenue Share Agreement with BXLS. 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. 37 Table of Contents 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. Our provision for state income taxes was $0.1 million and $0.2 million for the three and six months ended June 30, 2026, respectively. Our provision for state income taxes was $0.1 million and $0.2 million for the three and six months ended June 30, 2025, respectively. Results of Operations A discussion regarding our financial condition and results of operations for the three and six months ended June 30, 2026 compared to the three and six months ended June 30, 2025 is presented below. Comparison of the Three Months Ended June 30, 2026 and 2025 Results of Operations The following table summarizes our consolidated statements of operations for the periods presented (in thousands): THREE MONTHS ENDED JUNE 30, 2026 2025 $ CHANGE Operating expenses: Research and development $ 67,301 $ 55,703 $ 11,598 General and administrative 24,342 17,462 6,880 Merger transaction costs 4,361 — 4,361 Total operating expenses 96,004 73,165 22,839 Loss from operations (96,004 ) (73,165 ) (22,839 ) Other income, net: Interest income, net 11,808 7,141 4,667 Interest expense (1,580 ) — (1,580 ) Total other income, net 10,228 7,141 3,087 Net loss before taxes (85,776 ) (66,024 ) (19,752 ) Provision for income taxes (78 ) (72 ) (6 ) Net loss after taxes $ (85,854 ) $ (66,096 ) $ (19,758 ) 38 Table of Contents Research and Development Expense The following table summarizes our research and development expenses incurred for the periods presented (in thousands): THREE MONTHS ENDED JUNE 30, 2026 2025 External research and development costs by program: Zumilokibart $ 25,664 $ 22,052 APG990/APG279 3,310 3,975 APG333/APG273 397 1,185 APG531 1,142 — Unallocated research and development costs: External-discovery related costs and other(1) 7,303 6,774 Personnel-related (excluding equity-based compensation) 20,278 16,105 Equity-based compensation 9,129 5,538 Depreciation expense 78 74 Total research and development expenses $ 67,301 $ 55,703 (1)Includes research and development expenses related to APG808 Research and development expenses for the three months ended June 30, 2026 and 2025 were $67.3 million and $55.7 million, respectively. The increase of $11.6 million was primarily driven by the continued development of our zumilokibart program and higher personnel and equity-based compensation expenses associated with the growth in our research and development team. Research and development expense related to the zumilokibart program increased by $3.6 million in the three months ended June 30, 2026, compared to the three months ended June 30, 2025, primarily driven by an increase in clinical trial-related expenses associated with our APEX Phase 2 clinical trial. Research and development expenses related to the APG990/APG279 and APG333/APG273 programs decreased by $0.7 million and $0.8 million respectively, in the three months ended June 30, 2026, compared to the three months ended June 30, 2025, primarily due to decreases in preclinical research and development expenses. Research and development expense related to the APG531 program was $1.1 million for the three months ended June 30, 2026. No such expense was recorded in the three months ended June 30, 2025, as expenses were recorded to unallocated external-discovery related costs prior to 2026. Personnel-related expenses increased by $4.2 million in the three months ended June 30, 2026, compared to the three months ended June 30, 2025, primarily driven by increased headcount. Equity-based compensation expense increased by $3.6 million over the same period, primarily driven by the amortization of equity awards granted between the third quarter of 2025 and the second quarter of 2026. General and Administrative Expense The following table summarizes our general and administrative expenses for the periods presented (in thousands): THREE MONTHS ENDED JUNE 30, 2026 2025 Personnel-related (excluding equity-based compensation) $ 8,349 $ 6,395 Equity-based compensation 7,534 5,806 Legal and professional fees 1,116 1,211 Depreciation expense 331 325 Other 7,012 3,725 Total general and administrative expenses $ 24,342 $ 17,462 General and administrative expenses for the three months ended June 30, 2026 and 2025 were $24.3 million and $17.5 million, respectively. The increase of $6.9 million was primarily due to increases in personnel-related expenses of $2.0 million, driven by increased headcount and equity-based compensation of $1.7 million, primarily driven by the amortization of equity awards granted between the third quarter of 2025 and the second quarter of 2026. Additionally, other expenses increased by $3.3 million, primarily due to increases in IT and other employee-related expenses. 39 Table of Contents Merger Transaction Expense Merger transaction expense for the three months ended June 30, 2026 was $4.4 million, primarily related to legal costs and SEC fees incurred in connection with the Merger Agreement. Other Income, Net Other income, net increased $3.1 million for the three months ended June 30, 2026, compared to the three months ended June 30, 2025, primarily related to interest income earned on our cash, cash equivalents and marketable securities, partially offset by non-cash interest expense associated with our Revenue Share Agreement entered into during the second quarter of 2026. Comparison of the Six Months Ended June 30, 2026 and 2025 Results of Operations The following table summarizes our consolidated statements of operations for the periods presented (in thousands): SIX MONTHS ENDED JUNE 30, 2026 2025 $ CHANGE Operating expenses: Research and development $ 128,120 $ 102,090 $ 26,030 General and administrative 46,295 34,171 12,124 Merger transaction costs 4,361 — 4,361 Total operating expenses 178,776 136,261 42,515 Loss from operations (178,776 ) (136,261 ) (42,515 ) Other income, net: Interest income, net 20,548 14,981 5,567 Interest expense (1,580 ) — (1,580 ) Total other income, net 18,968 14,981 3,987 Net loss before taxes (159,808 ) (121,280 ) (38,528 ) Provision for income taxes (157 ) (155 ) (2 ) Net loss after taxes $ (159,965 ) $ (121,435 ) $ (38,530 ) Research and Development Expense The following table summarizes our research and development expenses incurred for the periods presented (in thousands): SIX MONTHS ENDED JUNE 30, 2026 2025 External research and development costs by program: Zumilokibart $ 45,206 $ 36,623 APG990/APG279 8,754 7,188 APG333/APG273 651 3,619 APG531 2,920 — Unallocated research and development costs: External-discovery related costs and other(1) 13,958 12,211 Personnel-related (excluding equity-based compensation) 38,820 31,401 Equity-based compensation 17,656 10,910 Depreciation expense 155 138 Total research and development expenses $ 128,120 $ 102,090 (1)Includes research and development expenses related to APG808 40 Table of Contents Research and development expenses for the six months ended June 30, 2026 and 2025 were $128.1 million and $102.1 million, respectively. The increase of $26.0 million was primarily driven by the continued development of our zumilokibart 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 program increased by $8.6 million in the six months ended June 30, 2026, compared to the six months ended June 30, 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 $1.6 million in the six months ended June 30, 2026, compared to the six months ended June 30, 2025, primarily due to an increase in clinical manufacturing activities and clinical trial expenses, partially offset by a decrease in preclinical research and development expenses. Research and development expense related to the APG333/APG273 program decreased by $3.0 million in the six months ended June 30, 2026, compared to the six months ended June 30, 2025, primarily due to a reduction in preclinical research and development expenses and clinical trial related expenses. Research and development expense related to the APG531 program was $2.9 million for the six months ended June 30, 2026. No such expense was recorded in the six months ended June 30, 2025, as expenses were recorded as unallocated external-discovery related costs prior to 2026. External-discovery related costs and other expenses increased by $1.7 million in the six months ended June 30, 2026, compared to the six months ended June 30, 2025, primarily driven by an increase in professional service fees, partially offset by a decrease in pre-clinical research and development expenses. Additionally, personnel-related expenses and equity-based compensation increased by $7.4 million and $6.7 million, respectively, in the six months ended June 30, 2026, compared to the six months ended June 30, 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): SIX MONTHS ENDED JUNE 30, 2026 2025 Personnel-related (excluding equity-based compensation) $ 16,334 $ 12,102 Equity-based compensation 16,162 11,560 Legal and professional fees 2,348 2,606 Depreciation expense 662 468 Other 10,789 7,435 Total general and administrative expenses $ 46,295 $ 34,171 General and administrative expenses for the six months ended June 30, 2026 and 2025 were $46.3 million and $34.2 million, respectively. The increase of $12.1 million was primarily due to increases in equity-based compensation and personnel-related expenses of $4.6 million and $4.2 million, respectively, primarily driven by increased headcount and an increase in the fair value of equity awards granted. Additionally, other expenses increased by $3.4 million, primarily driven by increases in IT, marketing and other employee related expenses. Merger Transaction Expense Merger transaction expense for the six months ended June 30, 2026 was $4.4 million, primarily related to legal costs and SEC fees incurred in connection with the Merger Agreement. Other Income, Net Other income, net increased $4.0 million for the six months ended June 30, 2026, compared to the six months ended June 30, 2025, primarily related to interest on our cash, cash equivalents and marketable securities, partially offset by non-cash interest expense associated with our Revenue Share Agreement entered into during the second quarter of 2026. Liquidity and Capital Resources On June 18, 2026, we entered into the Merger Agreement. Pursuant to the Merger Agreement, we have agreed to various covenants, including, among others, agreements to conduct our business in the ordinary course of business as was being conducted prior 41 Table of Contents to the date of the Merger Agreement. Outside of limited exceptions, we may not take, authorize, or agree or commit to take, enumerated actions without Parent’s consent, including, but not limited to: (i) acquiring businesses and disposing of significant assets; (ii) incurring capital expenditures above specified thresholds; (iii) issuing equity; (iv) incurring indebtedness; and (v) repurchasing or paying dividends on shares. We do not believe these restrictions will prevent us from being able to fund our operations, working capital needs or capital expenditure requirements. We could be required to pay Parent a termination fee of $381,273,716 if the Merger Agreement is terminated under specific circumstances described in the Merger Agreement. In addition, we expect to incur costs and expenses in connection with the Merger, a portion of which may be payable regardless of whether the Merger is completed. Payment of any such fees, costs or expenses could require us to use available cash that would otherwise be available for general corporate purposes or other uses. Sources of Liquidity Since our inception, we have incurred significant losses. We have not yet commercialized any of our programs, which are in various phases of early-stage and late-stage development, and we do not expect to generate revenue from sales of any of our programs for several years, if at all. To date, we have financed our operations from the proceeds from the issuance of preferred units and the sale of common stock in our initial public offering (“IPO”), our March 2024 Offering (as defined below), our ATM Facility, our October 2025 Offering (as defined below), our March 2026 Offering (as defined below) and our Revenue Share Agreement. As of June 30, 2026, we had cash and cash equivalents of $105.6 million, marketable securities of $866.4 million and long-term marketable securities of $321.9 million. Prior to our IPO, we received gross proceeds of $169.0 million from the sales of our preferred units. In connection with our IPO in July 2023, we issued and sold an aggregate of 20,297,500 shares of common stock (inclusive of 2,647,500 shares of common stock pursuant to the exercise in full of the underwriters’ option to purchase additional shares) at a price of $17.00 per share for net proceeds of $315.4 million, after deducting underwriting discounts and commissions and other offering expenses. In March 2024, we issued and sold an aggregate of 7,790,321 shares of 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 net proceeds of $450.0 million after deducting underwriting discounts and commissions, and other offering expenses (the “March 2024 Offering”). In August 2024, we entered into an Open Market Sale Agreement (the “Sale Agreement”) with Jefferies LLC (the “Sales Agent”), pursuant to which we may offer and sell shares of common stock up to a maximum aggregate offering price of $300.0 million, from time to time, through an ATM Facility. During the year ended December 31, 2024, we sold 926,049 shares of common stock under the ATM Facility for gross proceeds of $44.9 million, less commissions and other offering expenses of $1.4 million. During the year ended December 31, 2025, we sold 1,175,701 shares of common stock under the ATM Facility for gross proceeds of $67.6 million, less commissions and other offering expenses of $2.0 million. During the three months ended June 30, 2026, we sold 369,220 shares of common stock under the ATM Facility for gross proceeds of $29.7 million, less commissions and other offering expenses of $0.8 million. As of June 30, 2026, $157.8 million remained available for sale under the Sale Agreement. In October 2025, we issued and sold an aggregate of 8,048,782 shares of common stock (inclusive of 1,097,561 shares of common stock pursuant to the exercise in full of the underwriters’ option to purchase additional shares) at a public offering price of $41.00 per share, and, in lieu of common stock to certain investors, pre-funded warrants to purchase up to 365,853 shares of common stock at a public offering price of $40.99999 per pre-funded warrant (the “October 2025 Offering”). The pre-funded warrants have an exercise price of $0.00001 per share and are exercisable immediately. The aggregate net proceeds from the offering were $324.1 million after deducting underwriting discounts and commissions and estimated offering expenses payable by us. In March 2026, 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. In May 2026, we entered into the Revenue Share Agreement with BXLS, pursuant to which, in exchange for an upfront payment of $100.0 million, BXLS purchased the right to receive tiered Revenue Share Payments with respect to annual worldwide Net Sales of zumilokibart. 42 Table of Contents Future Funding Requirements To date, we have not generated any revenue from product sales. We do not expect to generate revenue from product sales unless and until we successfully complete preclinical and clinical development of, receive regulatory approval for, and commercialize a product candidate and we do not know when that will occur, if at all. We expect our expenses to increase substantially in connection with our ongoing activities, particularly as we advance the preclinical and clinical activities. In addition, if we obtain regulatory approval for any product candidates, we expect to incur significant expenses related to product sales, marketing, and distribution to the extent that such sales, marketing and distribution are not the responsibility of potential collaborators. We expect to incur additional costs associated with operating as a public company. The timing and amount of our operating expenditures will depend largely on the factors set out above. For more information, see the section titled “Risk Factors—Risks Related to Our Limited Operating History, Financial Position and Capital Requirements.” Our funding requirements and timing and amount of our operating expenditures will depend on many factors, including, but not limited to: •the rate of progress in the development of our zumilokibart, APG279, APG273, APG990, APG333, APG531 and APG808 programs; •the scope, results and costs of preclinical studies and clinical trials for any other current and future programs; •the number and characteristics of programs and technologies that we develop or may in-license; •the costs and timing of potential future commercialization activities, including manufacturing, marketing, sales and distribution, for any of our product candidates for which we receive marketing approval; •the costs necessary to obtain regulatory approvals, if any, for any approved products in the United States and other jurisdictions, and the costs of post-marketing studies that could be required by regulatory authorities in jurisdictions where approval is obtained; •the costs and timing of preparing, filing and prosecuting patent applications, maintaining and enforcing our intellectual property rights and defending any intellectual property-related claims, including claims of infringement, misappropriation or other violation of third-party intellectual property; •the continuation of our existing licensing arrangements and entry into new collaborations and licensing arrangements; •the costs we incur in maintaining business operations; •the costs of hiring additional clinical, quality control, manufacturing and other scientific personnel; •the costs of adding operational, financial and management information systems and personnel; •adverse global macroeconomic conditions, including inflation, slower growth or recession, new or increased tariffs and other barriers to trade, geopolitical conflict, changes to fiscal and monetary policy or government budget dynamics (particularly in the pharmaceutical and biotech areas), government shutdowns, volatility in financial markets and other challenges in the global economy; •the costs associated with being a public company; •the costs and timing of future laboratory facilities; •the revenue, if any, received from commercial sales of our product candidates for which we receive marketing approval; •the effect of competing technological and market developments; and •the extent to which we acquire or invest in businesses, products and technologies, including entering into licensing or collaboration arrangements for programs. Identifying potential programs and product candidates and conducting preclinical studies and clinical trials is a time consuming, expensive and uncertain process that takes years to complete, and we may never generate the necessary data or results required to obtain marketing approval and achieve product sales. In addition, our product candidates, if approved, may not achieve commercial success. Our commercial revenues, if any, will be derived from sales of products that we do not expect to be commercially available for many years, if ever. Accordingly, we may need to obtain additional funds to achieve our business objectives. 43 Table of Contents We do not have any committed external sources of funds. Although we have entered into the Revenue Share Agreement, additional milestone payments under the Revenue Share Agreement are subject to the satisfaction of conditions, which may not be met. And, adequate additional financing may not be available to us on acceptable terms, or at all. To the extent that we raise additional capital through the sale of equity or convertible debt securities, our stockholders’ ownership interests could be diluted, and the terms of these securities may include liquidation or other preferences that could adversely affect our stockholders’ rights. Additional debt financing and preferred equity financing, if available, may involve agreements that include covenants limiting or restricting our ability to take specific actions, such as incurring debt, making capital expenditures or declaring dividends, and may require the issuance of warrants, which could potentially dilute our stockholders’ ownership interests. If we raise additional funds through strategic collaborations, licensing arrangements, royalty financings or other collaborations with third parties, we may have to relinquish valuable rights to our technologies, future revenue streams, research programs, or product candidates or grant licenses on terms that may not be favorable to us. Any additional fundraising efforts may divert our management from their day-to-day activities, which may adversely affect our business. If we are unable to raise additional funds when needed or on acceptable terms, we may be required to delay, limit, suspend, or terminate our product development programs or any future commercialization efforts or grant rights to develop and market product candidates to third parties that we would otherwise prefer to develop and market ourselves. As of June 30, 2026, we had $105.6 million of cash and cash equivalents, $866.4 million of marketable securities and $321.9 million of long-term marketable securities. Based on our current operating plan, as of the date of this Quarterly Report, we estimate that our existing cash, cash equivalents, marketable securities, and long-term marketable securities will be sufficient to enable us to fund our operating expenses and capital expenditure requirements through at least the next 12 months following the issuance of our consolidated financial statements included elsewhere in this Quarterly Report. We have based this estimate on assumptions that may prove to be wrong, and we could exhaust our available capital resources sooner than we expect. Cash Flows The following table provides information regarding our cash flows for the periods presented (in thousands): SIX MONTHS ENDED JUNE 30, 2026 2025 Net cash, cash equivalents, and restricted cash provided by (used in): Operating activities $ (126,950 ) $ (110,506 ) Investing activities (417,212 ) 91,107 Financing activities 518,184 1,802 Net decrease in cash, cash equivalents, and restricted cash $ (25,978 ) $ (17,597 ) Net Cash used in Operating Activities Cash used in operating activities resulted primarily from our net losses adjusted for non-cash charges and changes in components of operating assets and liabilities, which are generally attributable to timing of payments, and the related effect on certain account balances, operational and strategic decisions and contracts to which we may be a party. For the six months ended June 30, 2026, operating activities used $127.0 million of cash, primarily due to a net loss of $160.0 million, amortization of discounts on marketable securities of $3.3 million, and net changes in operating assets and liabilities of $1.9 million. This was partially offset by non-cash charges of $33.8 million, $2.0 million, and $1.6 million for equity-based compensation, non-cash lease expense, and non-cash interest expense, respectively, For the six months ended June 30, 2025, operating activities used $110.5 million of cash, primarily due to a net loss of $121.4 million, net changes in our operating assets and liabilities of $9.8 million and amortization of discounts on marketable securities of $4.1 million. This was partially offset by non-cash charges of $22.5 million and $1.8 million for equity-based compensation and lease expense, respectively. 44 Table of Contents Net Cash (used in) provided by Investing Activities For the six months ended June 30, 2026, net cash used in investing activities was $417.2 million, primarily related to the $736.0 million purchase of marketable securities. This was partially offset by $318.8 million in maturities of marketable securities. For the six months ended June 30, 2025, net cash provided by investing activities was $91.1 million primarily related to $241.8 million in maturities of marketable securities. This was partially offset by the $145.6 million purchase of marketable securities and $5.1 million purchase of property and equipment. Net Cash provided by Financing Activities For the six months ended June 30, 2026, financing activities provided $518.2 million of cash, primarily due to $377.4 million of net proceeds from the issuance of common stock, $97.8 million of proceeds from the Revenue Share Agreement with BXLS, $28.9 million of net proceeds from our ATM Facility, and $14.1 million of proceeds from the exercise of stock options and employee stock purchase plan purchases. For the six months ended June 30, 2025, financing activities provided $1.8 million of cash, primarily related to the exercise of stock options. Contractual Obligations and Other Commitments We enter into contracts in the normal course of business with CROs, contract manufacturing organizations (“CMOs”) and other third parties for preclinical research studies and testing, clinical trials, manufacturing and other services. As of June 30, 2026, payments due upon cancellation consist only of payments for services provided and expenses incurred up to the date of cancellation, including non-cancelable obligations of our service providers and, in some cases, wind-down costs, or an exit fee. The exact amounts of such obligations are dependent on the timing of termination and the terms of the associated agreement. Accordingly, these payments are not disclosed as the amount and timing of such payments are not known. Our agreements to license intellectual property include potential milestone payments that are dependent upon the development of products using the intellectual property licensed under the agreements and contingent upon the achievement of specific development and clinical milestones. As of June 30, 2026, we have incurred $17.0 million of the maximum aggregate potential milestone payments. We are also obligated to pay royalties to (i) Paragon at a royalty rate of a low single-digit percentage based on net sales of any products under the License Agreements, once commercialized and (ii) WuXi Biologics at a royalty rate of a fraction of a single digit percentage of global net sales of WuXi Biologics Licensed Products manufactured by a third-party manufacturer. We do not have any off-balance sheet arrangements that are material or reasonably likely to become material to our financial condition or results of operations. Critical Accounting Policies and Significant Judgments and Estimates Our management’s discussion and analysis of our financial condition and results of operations is based on our consolidated financial statements, which have been prepared in accordance with generally accepted accounting principles in the United States. The preparation of these condensed consolidated financial statements requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements, as well as the reported revenues recognized and expenses incurred during the reporting periods. Our estimates are based on our historical experience and on various other factors that we believe are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying value of assets and liabilities that are not readily apparent from other sources. Actual results may differ from these estimates under different assumptions or conditions. We define our critical accounting policies as those accounting principles generally accepted in the United States of America that are most critical to the judgments and estimates used in the preparation of our condensed consolidated financial statements. While our significant accounting policies are described in more detail in Note 2 to our condensed consolidated financial statements appearing elsewhere in this Quarterly Report, we believe that our most critical accounting policies are those relating to Research and Development Expenses, which are described under the heading “Management’s Discussion and Analysis of Financial Condition and Results of Operations – Critical Accounting Policies and Significant Judgment and Estimates” in our Annual Report on Form 10-K. There have been no material changes to our critical accounting policies from those described in the Annual Report on Form 10-K apart from the estimates for our Revenue Share Liability as described below. 45 Table of Contents Revenue Share Liability The revenue share liability represents amounts received from BXLS under the Revenue Share Agreement, which we account for as a debt financing under ASC 470. It is initially recorded net of debt issuance costs and subsequently measured using the effective interest method, with the carrying amount increasing for non-cash interest expense and decreasing as Revenue Share Payments are made to BXLS. Our estimates of future Revenue Share Payments involve a number of judgments and assumptions, including but not limited to the timing of regulatory approval and commercial launch of zumilokibart, projected net product sales, and market penetration. Key assumptions are reviewed at each reporting date and adjusted as needed. Changes in any one of these assumptions could materially impact the effective interest rate and carrying value of the liability, as well as the amount of non-cash interest expense recognized in future periods. Recently Issued Accounting Pronouncements We have reviewed all recently issued accounting standards and have determined that, other than as disclosed in Note 2 to our condensed consolidated financial statements included elsewhere in this Quarterly Report, such standards are not expected to have a material impact on our consolidated financial statements or do not otherwise apply to our operations. 46 Table of Contents