ANAPTYSBIO, INC. (ANAB)

In December 2025, Vanda announced the submission of a BLA to the FDA for imsidolimab in GPP. The FDA accepted the BLA filing for imsidolimab in GPP in February 2026 with a target action date of December 12, 2026. Pursuant to the terms of the Vanda License Agreement, we received an upfront payment of $10.0 million and a $5.0 million payment for existing drug supply. We are also eligible to receive a 10% royalty on net sales under the Vanda License Agreement: The Separation and Distribution Agreement provides that any and all rights to receive milestone payments under the Vanda License Agreement will be allocated to First Tracks Biotherapeutics. For more information about these collaborations, see Note 4 — Collaborative Research and Development Agreements in the accompanying notes to the consolidated financial statements.

Cash Flows The following table summarizes our cash flows for the three months ended March 31, 2026 and 2025: Three Months Ended March 31, (in thousands) 2026 2025 Net cash provided by (used in): Operating activities $ (25,919 ) $ (10,700 ) Investing activities 34,983 14,847 Financing activities 1,209 (28,590 ) Net increase (decrease) in cash and cash equivalents $ 10,273 $ (24,443 ) 26 Operating Activities Net cash used in operating activities during the three months ended March 31, 2026 was $25.9 million, primarily due to our net loss of $52.9 million, adjusted for addbacks for non-cash items of $35.7 million which includes stock-based compensation, amortization of operating right-of-use assets, non-cash interest expense, income from marketable securities, and depreciation, offset by decreases in working capital of $8.7 million, which includes decreases related to accounts payable and other liabilities, and […]

Factors that could cause or contribute to such differences include, but are not limited to, those identified below and those discussed in the section entitled “Risk Factors” included in Part II, Item 1A of this Quarterly Report. You should also carefully read “Special Note Regarding Forward-Looking Statements”. Overview Prior to the separation described below, we were a clinical-stage biotechnology company focused on delivering innovative immunology therapeutics for autoimmune and inflammatory diseases. Our clinical-stage pipeline included rosnilimab, a selective pathogenic T cell depleter, for which we completed a Phase 2b trial for the treatment of moderate-to-severe rheumatoid arthritis (“RA”), ANB033, a CD122 antagonist, in a Phase 1b trial for celiac disease (“CeD”) and eosinophilic esophagitis (“EoE”), and ANB101, a BDCA2 modulator, in a Phase 1a trial.

We also discovered and out-licensed, in financial collaborations, multiple therapeutic antibodies, including a PD-1 antagonist ( Jemperli (dostarlimab-gxly) or “ Jemperli ”) to GSK and an IL-36R antagonist (imsidolimab) to Vanda Pharmaceuticals Inc. (“Vanda”). We recognize revenue from milestones and royalties achieved under our immuno-oncology collaboration with GSK and license and transition services revenue from our collaboration with Vanda. First Tracks Biotherapeutics Separation In September 2025, we announced that our board of directors (“Board of Directors”) approved plans to explore separating our business into two independent, publicly traded companies. We would hold and continue to manage the financial collaboration for Jemperli with GSK and for imsidolimab with Vanda, with a focus on protecting and returning value of the royalties to its stockholders.

The spun-out company would be a clinical-stage biotechnology company focused on the development and potential commercialization of innovative therapeutics for autoimmune and inflammatory diseases, including rosnilimab, ANB033 and ANB101. This separation was completed on April 20, 2026. In connection with the separation, we entered into a separation and distribution agreement (the “Separation and Distribution Agreement”) with First Tracks Biotherapeutics, Inc. (“First Tracks Biotherapeutics”). The Separation and Distribution Agreement identifies the assets transferred to (including contracts assigned) or retained by, and the liabilities assumed or retained by, each of us and First Tracks Biotherapeutics. As the separation occurred after March 31, 2026, the results of First Tracks Biotherapeutics are included in our consolidated financial statements.

Collaborative Programs GSK Collaboration Multiple company-discovered antibody programs have been advanced to preclinical and clinical milestones under our collaborations. Our collaborations include an immuno-oncology-focused collaboration with GSK. Under the GSK Agreement, a Biologics License Application (“BLA”) for Jemperli (dostarlimab), a PD-1 antagonist antibody, was approved by the FDA in April 2021 for the treatment of advanced or recurrent deficient mismatch repair endometrial cancer (“dMMREC”). In February 2023, the FDA granted full approval for this indication. In addition, in April 2021, the European Medicines Agency (“EMA”) granted conditional marketing authorization in the European Union (“EU”) for Jemperli for use in women with mismatch repair deficient (“dMMR”)/microsatellite instability-high (“MSI-H”) recurrent or advanced endometrial cancer who have progressed on or following prior treatment with a platinum containing regimen.

A second FDA approval was received in August 2021 for Jemperli in pan-deficient mismatch repair tumors (PdMMRT). In July 2023, the FDA approved Jemperli in combination with chemotherapy for the treatment of adult patients with dMMR MSI-H primary advanced or recurrent endometrial cancer. In December 2023, the EMA approved Jemperli plus chemotherapy for dMMR/MSI-H primary advanced or recurrent 22 endometrial cancer. In August 2024, the FDA approved Jemperli plus chemotherapy for all adult patients with primary advanced or recurrent endometrial cancer. In January 2025, the EMA approved Jemperli plus chemotherapy for this same indication. […]

• We and/or our collaborators may be unable to obtain, or may be delayed in obtaining, required regulatory approvals in the United States or in foreign jurisdictions, which would materially impair our ability to commercialize and generate revenue from our product candidates. • Even if our product candidates receive regulatory approval, they will be subject to significant post-marketing regulatory requirements. • We may not be successful in our efforts to expand our pipeline of product candidates and develop marketable products. • We are assessing advancement to Phase 3 of clinical development of rosnilimab for RA, and have no history of commercializing biotechnology products, which may make it difficult to evaluate the prospects for our future viability.

• We face significant competition, and if our competitors develop and market products that are more effective, safer or less expensive than our product candidates, our commercial opportunities will be negatively impacted. • Our product candidates may not achieve adequate market acceptance among physicians, patients, health care payors and others in the medical community necessary for commercial success. • We currently have no marketing and sales force. If we are unable to establish effective sales or marketing capabilities or enter into agreements with third parties to sell or market our product candidates, we may not be able to effectively sell or market our product candidates, if approved, or generate product revenue.

• The manufacture of biologics is complex, and our third party manufacturers may encounter difficulties in production. If any of our third party manufacturers encounter such difficulties, our ability to provide supply of our product candidates for clinical trials, our ability to obtain marketing approval, or our ability to provide supply of our products for patients, if approved, could be delayed or stopped. • Political, economic or public health events may have a material impact on the U.S. and global economies and could have a material adverse impact on our employees, contractors and patients, which could adversely and materially impact our business, financial condition and results of operations. • We have limited operating revenue and a history of operational losses and may not achieve or sustain profitability.

• We have no products approved for commercial sale, and to date we have not generated any revenue or profit from sales of our product candidates. 23 • We will require additional capital to finance our operations, which may not be available to us on acceptable terms, or at all. As a result, we may not complete the development and commercialization of our product candidates or develop new product candidates. • The proposed separation of our business into two independent, publicly traded companies is subject to various risks and uncertainties and may not be completed on the terms or timeline currently contemplated, if at all. • Our existing collaboration with GSK and other collaborations are important to our business, and other future collaborations may also be important to us.

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• We are heavily dependent on GSK for the successful commercialization and development of Jemperli under the GSK Agreement. If GSK does not devote sufficient resources to the commercialization or development of Jemperli , is unsuccessful in its efforts, or chooses to reprioritize its commercial programs, our business would be materially harmed. • Jemperli faces substantial competition for its intended uses in the targeted markets from products discovered, developed and commercialized both by GSK and by other pharmaceutical companies, which could cause the royalties payable to us pursuant to the GSK Agreement to be less than expected, which in turn would harm our business and cause the price of our securities to fall.

• The recent separation of our business into two independent, publicly traded companies is subject to continued risks and uncertainties, and completion of the tasks relating to the separation will continue to involve time, effort and expense, which could harm our business, results of operations and financial condition. • If we are unable to obtain or protect intellectual property rights, we may not be able to compete effectively in our market. 29 • We currently have a limited number of employees, and our future success depends on our ability to retain our key executives and to attract, retain and motivate qualified personnel. • The market price of our stock has been and may continue to be volatile, and you could lose all or part of your investment.

Risks Related to Continued Commercialization Success of Jemperli We derive substantially all of our revenues from GSK’s commercialization of Jemperli . As a result, our business and financial results and prospects heavily depend on GSK’s ability to successfully develop and commercialize Jemperli . We derive substantially all of our revenues from GSK’s commercialization of Jemperli . Royalty revenues from Jemperli have represented and are expected to represent substantially all of our future revenues. The amount and timing of revenue from such royalties are unknown and highly uncertain. Pursuant to the GSK Agreement, GSK is responsible for the development and commercialization of Jemperli .

As a result, our business and financial results and prospects depend upon the performance by GSK of its commercial obligations under the GSK Agreement and the commercial success of Jemperli . We have no control over GSK’s marketing and sales efforts, and GSK might not be successful, which would harm our business and cause the price of our securities to fall. Our quarterly royalty revenues may fluctuate due to a variety of factors, many of which are outside of our control. The amount of royalties and milestone payments, if any, we receive will depend on many factors, including but not limited to the following: • the extent and effectiveness of the sales and marketing and distribution support GSK provides to Jemperli ; […]

Management’s Discussion and Analysi s of Financial Condition and Results of Operations You should read the following discussion and analysis of our financial condition and results of operations together with the historical consolidated financial statements and the notes thereto included in Part II, Item 8—Consolidated Financial Statements and Supplementary Data of this Annual Report on Form 10-K. This discussion and other sections of this Annual Report contain forward-looking statements that involve risks and uncertainties, such as our plans, objectives, expectations, intentions, and beliefs. Our actual results could differ materially from those discussed in these forward-looking statements. Factors that could cause or contribute to such differences include, but are not limited to, those identified below and those discussed in the section entitled “Risk Factors” included in Part I, Item 1A of this Annual Report.

You should also carefully read “Special Note Regarding Forward-Looking Statements”. Overview We are a clinical-stage biotechnology company focused on delivering innovative immunology therapeutics for autoimmune and inflammatory diseases. Our clinical-stage pipeline includes rosnilimab, a selective pathogenic T cell depleter, for which we completed a Phase 2b trial for the treatment of moderate-to-severe rheumatoid arthritis (“RA”), ANB033, a CD122 antagonist, in a Phase 1b trial for celiac disease (“CeD”) and eosinophilic esophagitis (“EoE”), and ANB101, a BDCA2 modulator, in a Phase 1a trial. We also discovered and out-licensed, in financial collaborations, multiple therapeutic antibodies, including a PD-1 antagonist (Jemperli (dostarlimab-gxly) or “Jemperli”) to GSK and an IL-36R antagonist (imsidolimab) to Vanda Pharmaceuticals Inc.

(“Vanda”). We currently recognize revenue from milestones and royalties achieved under our immuno-oncology collaboration with GSK and license and transition services revenue from our collaboration with Vanda. Intention to Separate Company In September 2025, we announced that our board of directors (“Board of Directors”) approved plans to explore separating our business into two independent, publicly traded companies. One company is expected to hold and continue to manage the financial collaboration for Jemperli from GSK and for imsidolimab from Vanda, with a focus on protecting and returning value of the royalties to its shareholders. The other company is expected to be a clinical-stage biotechnology company focused on the development and potential commercialization of innovative therapeutics for autoimmune and inflammatory diseases, including rosnilimab, ANB033 and ANB101.

Upon completion of the proposed separation, which we expect to complete in the second quarter of 2026, we intend to launch the clinical-stage biotechnology company with adequate capital to fund operations for at least twelve months after the date the proposed separation is completed. While the proposed separation is anticipated to be a taxable event, we are focused on minimizing overall corporate and shareholder-level taxes across the entire transaction. Completion of the proposed separation is subject to final approval by our Board of Directors and other customary conditions, including the effectiveness of a registration statement with the Securities and Exchange Commission (the “SEC”). Our Wholly Owned Clinical-Stage Pipeline Our antibodies are in development to treat inflammatory diseases.

We believe these molecules have potential applicability across a broad range of autoimmune and inflammatory diseases, including in gastroenterology, rheumatology, dermatology, respiratory, and other therapeutic areas. Rosnilimab Rosnilimab is an IgG1 antibody that directly targets pathogenic T cells, such as activated Tph/Tfh and T effector cells, in the periphery or inflamed tissue. These T cells, when activated, proliferate and migrate, and secrete the inflammatory cytokines that are the drivers of autoimmune and inflammatory diseases. Rosnilimab is designed to selectively deplete pathogenic T cells in both inflamed tissue and the periphery while sparing non-pathogenic T cells, including naïve T cells, to preserve overall immune function and restore immune homeostasis. This drives specific immunological outcomes, such as a reduction in T cell proliferation, migration and cytokine secretion, and a reduction of plasma cell generation and autoantibody levels.

We announced top-line data from a healthy volunteer Phase 1 trial of rosnilimab in November 2021 that supported advancement of rosnilimab into subsequent patient trials. A total of 144 subjects were enrolled in the randomized, double-blind, placebo-controlled healthy volunteer Phase 1 trial, where single ascending dose (“SAD”) cohorts received subcutaneous (“SC”) or intravenous (“IV”) single doses of rosnilimab up to 600mg or placebo, while multiple ascending dose (“MAD”) cohorts received four weekly subcutaneous doses of rosnilimab ranging up to 400mg or placebo. Rosnilimab was generally well-tolerated and no dose-limiting toxicities were observed. Rosnilimab demonstrated a sustained systemic exposure and dose-proportionality with an estimated two-week half-life for subcutaneous and IV routes of administration.

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