Note 1 - Organization and Basis of Presentation	3 Months Ended
Mar. 31, 2026
Notes to Financial Statements
Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]	Note 1—Organization and Basis of Presentation General Omeros Corporation (“Omeros,” the “Company” or “we”) is an innovative, commercial-stage biotechnology company that discovers and develops first-in-class protein and small-molecule therapeutics for large-market and orphan indications, with particular emphasis on complement-mediated diseases, cancers, and addictive or compulsive disorders. Our clinical-stage development programs include: narsoplimab, our antibody targeting mannan-binding lectin-associated serine protease 2 (“MASP-2”), the effector enzyme of the lectin pathway of complement; OMS1029, our long-acting antibody targeting MASP-2; and OMS527, our phosphodiesterase 7 (“PDE7”) inhibitor program. During 2025, we entered into an Asset Purchase and License Agreement (“APLA”) with Novo Nordisk Health Care AG (“Novo Nordisk”) for exclusive global rights in all indications to develop and commercialize zaltenibart, also known as OMS906, our lead antibody targeting mannan-binding lectin-associated serine protease-3 (“MASP-3”), the key activator of the alternative pathway of complement. We retain rights to our MASP-3 small-molecule program, including the ability to develop and commercialize small-molecule MASP-3 inhibitors across a range of therapeutic areas, including, but not limited to, ophthalmology, neurology, gastrointestinal disorders, dermatology, musculoskeletal diseases, and oncology. We also retain rights to develop our “grandfathered” MASP-3 antibodies, with temporal and indication restrictions on commercialization, and for use in advancing our small-molecule therapeutics. FDA Approval of YARTEMLEA^® On December 23, 2025, FDA approved YARTEMLEA^® (narsoplimab-wuug) for the treatment of hematopoietic stem cell transplant-associated thrombotic microangiopathy (“TA-TMA”). TA-TMA is a severe and often-fatal complication of hematopoietic stem cell transplantation in adults and children, driven by systemic endothelial injury triggered by conditioning regimens, immunosuppressants, infection, graft-versus-host disease, and other transplant-related factors. Activation of the lectin pathway of complement plays a central role in disease pathogenesis. YARTEMLEA selectively inhibits MASP-2, blocking pathway activation while preserving classical and alternative complement pathway functions important for host defense. In TA-TMA, MASP-2 inhibition prevents lectin pathway-mediated cellular injury, including endothelial damage in small blood vessels, and thrombus formation. YARTEMLEA is the first and only approved inhibitor of the lectin pathway of complement. YARTEMLEA is approved for the treatment of TA-TMA in adults and in children ages two years and older. Commercial distribution and sales of YARTEMLEA commenced in January 2026. A marketing authorization application (“MAA”) for YARTEMLEA in TA-TMA has been submitted to the European Medicines Agency (“EMA”) and is being reviewed under EMA’s centralized review procedure, which allows review of a single marketing authorization application. If the MAA is approved, it would authorize the product to be marketed in all European Union (“EU”) member states and European Economic Area countries. The European Commission has granted narsoplimab designation as an orphan medicinal product for treatment in hematopoietic stem cell transplantation. For commercialization of YARTEMLEA outside the U.S., we are evaluating potential partnerships, including broad ex-U.S. and regional collaborations. Sale of Zaltenibart On November 25, 2025, we completed a transaction (the “Transaction”) pursuant to the APLA between Omeros and Novo Nordisk, dated October 10, 2025, in which Novo Nordisk received exclusive global rights in all indications to develop and commercialize our lead investigational MASP-3 inhibitor, zaltenibart (formerly OMS906), and certain related compounds and products. Zaltenibart is a first-in-class, late-stage clinical humanized monoclonal antibody targeting MASP-3, the most upstream and key activator of the alternative pathway of the complement system. Zaltenibart has shown multiple potential advantages over other alternative pathway inhibitors in development and on the market. At the closing of the Transaction, we received an upfront cash payment of $240.0 million. In addition, we are eligible to receive (i) up to $510.0 million in one-time milestone payments upon the first achievement by Novo Nordisk or its affiliates or sublicensees of each of the development and approval milestone events as set forth in the APLA and (ii) up to $1.3 billion in one-time milestone payments upon the first achievement by Novo Nordisk or its affiliates or sublicensees of certain sales-based milestone events as set forth in the APLA. We are also eligible under the APLA to receive tiered royalties on annual net sales of products at percentage rates ranging from high single digit to high teens, subject to reduction in certain circumstances, as set forth in the APLA. In total, we are eligible to receive up to an additional $1.8 billion in potential development and commercial milestones, plus tiered royalties on net sales. Pursuant to the APLA, we sold and transferred, and Novo Nordisk purchased, zaltenibart and certain related assets, and the parties agreed to grant and receive certain intellectual property licenses to facilitate the continued development and commercialization activities of both companies. We retain rights to our MASP-3 small-molecule program unrelated to zaltenibart, including the ability to develop and commercialize small-molecule MASP-3 inhibitors, across a range of therapeutic areas, including, but not limited to, ophthalmology, neurology, gastrointestinal disorders, dermatology, musculoskeletal diseases and oncology. We also retain rights to our “grandfathered” MASP-3 antibodies, with temporal and indication restrictions on commercialization and for use in advancing our small-molecule therapeutics. In accordance with the APLA, at the closing of the Transaction, Omeros and Novo Nordisk entered into a transition services agreement (the “Transition Services Agreement”) pursuant to which we are providing certain transition services to Novo Nordisk to facilitate the transfer of the acquired assets and liabilities under the APLA and to provide for the continued operation of relevant studies and program activities during the applicable term. Subject to certain exceptions and limitations, Novo Nordisk reimburses us for costs and expenses we incur under the Transition Services Agreement, including third-party costs and expenses, costs associated with delivery of transition services by Omeros personnel on an hourly basis at rates specified in the Transition Services Agreement, and for our inventories of zaltenibart drug substance and product. Other Development Programs Our lectin pathway program also includes OMS1029, our long-acting antibody targeting MASP-2. We have completed Phase 1 clinical trials evaluating both single-ascending and multiple ascending doses of OMS1029. Results of these studies support once-quarterly dosing administered either intravenously or subcutaneously. OMS1029 has been well tolerated to date with no safety concerns identified. We are working to finalize selection of an indication and initiate Phase 2 clinical development of OMS1029. In addition, we have selected a development candidate for our MASP-2 small molecule program, which is advancing to Investigational New Drug (“IND”)-enabling studies targeting once-daily oral administration. Our PDE7 inhibitor program, which we refer to as OMS527, comprises multiple PDE7 inhibitor compounds and is based on our discoveries of previously unknown links between PDE7 and any addiction or compulsive disorder, and between PDE7 and any movement disorder. In April 2023, we were awarded a grant from the National Institute on Drug Abuse (“NIDA”), to develop an orally administered PDE7 inhibitor compound for the treatment of cocaine use disorder. NIDA awarded the grant to us for a total of $6.24 million over three years, of which we have claimed and received $2.3 million of funding to date. FDA subsequently requested additional nonclinical information prior to initiating the clinical in-patient study. Following a meeting with FDA to discuss that request, we are working with FDA to streamline the path to initiate the in-patient clinical trial, which is targeted for initiation by year-end 2026. We also have various programs in preclinical research and development. We continue to progress preclinical studies within our novel oncology program, which is focused on developing novel, proprietary large molecule therapeutics designed to selectively target and kill dividing cancer cells. We have completed selection of a drug development candidate, and IND-enabling studies are underway for this program, which we refer to as OncotoX-AML. Acute myeloid leukemia (“AML”), an aggressive and highly fatal bone marrow and blood cancer, is the lead indication for development. We are also advancing our targeted complement activating therapy (“T-CAT”) platform: a new class of recombinant antibodies intended for broad action against pathogens, including bacteria, fungi, viruses, and parasites. T-CAT is designed to harness complement activation to kill pathogens directly, which represents a novel approach to infectious disease treatment. Our initial focus is on T-CAT’s potential against multidrug-resistant organisms. Basis of Presentation Our condensed consolidated financial statements include the financial position and results of operations of Omeros and our wholly owned subsidiaries. All inter-company transactions have been eliminated. The accompanying condensed consolidated financial statements reflect all adjustments, consisting of normal recurring adjustments and non-recurring adjustments, considered necessary for the fair presentation of such information. Our financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”). Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Significant items subject to such estimates include revenue recognition and the valuations of the OMIDRIA contract royalty asset, the OMIDRIA royalty obligation, and the embedded derivatives associated with our debt. We base our estimates on historical experience and on various other factors that we believe are reasonable under the circumstances; however, actual results could differ from these estimates.

Note 1 - Organization and Basis of Presentation

3 Months Ended

Mar. 31, 2026

Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]

Note 1—Organization and Basis of Presentation

General

Omeros Corporation (“Omeros,” the “Company” or “we”) is an innovative, commercial-stage biotechnology company that discovers and develops first-in-class protein and small-molecule therapeutics for large-market and orphan indications, with particular emphasis on complement-mediated diseases, cancers, and addictive or compulsive disorders.

Our clinical-stage development programs include: narsoplimab, our antibody targeting mannan-binding lectin-associated serine protease 2 (“MASP-2”), the effector enzyme of the lectin pathway of complement; OMS1029, our long-acting antibody targeting MASP-2; and OMS527, our phosphodiesterase 7 (“PDE7”) inhibitor program. During 2025, we entered into an Asset Purchase and License Agreement (“APLA”) with Novo Nordisk Health Care AG (“Novo Nordisk”) for exclusive global rights in all indications to develop and commercialize zaltenibart, also known as OMS906, our lead antibody targeting mannan-binding lectin-associated serine protease-3 (“MASP-3”), the key activator of the alternative pathway of complement. We retain rights to our MASP-3 small-molecule program, including the ability to develop and commercialize small-molecule MASP-3 inhibitors across a range of therapeutic areas, including, but not limited to, ophthalmology, neurology, gastrointestinal disorders, dermatology, musculoskeletal diseases, and oncology. We also retain rights to develop our “grandfathered” MASP-3 antibodies, with temporal and indication restrictions on commercialization, and for use in advancing our small-molecule therapeutics.

FDA Approval of YARTEMLEA^®

On December 23, 2025, FDA approved YARTEMLEA^® (narsoplimab-wuug) for the treatment of hematopoietic stem cell transplant-associated thrombotic microangiopathy (“TA-TMA”). TA-TMA is a severe and often-fatal complication of hematopoietic stem cell transplantation in adults and children, driven by systemic endothelial injury triggered by conditioning regimens, immunosuppressants, infection, graft-versus-host disease, and other transplant-related factors. Activation of the lectin pathway of complement plays a central role in disease pathogenesis. YARTEMLEA selectively inhibits MASP-2, blocking pathway activation while preserving classical and alternative complement pathway functions important for host defense. In TA-TMA, MASP-2 inhibition prevents lectin pathway-mediated cellular injury, including endothelial damage in small blood vessels, and thrombus formation.

YARTEMLEA is the first and only approved inhibitor of the lectin pathway of complement. YARTEMLEA is approved for the treatment of TA-TMA in adults and in children ages two years and older.

Commercial distribution and sales of YARTEMLEA commenced in January 2026.

A marketing authorization application (“MAA”) for YARTEMLEA in TA-TMA has been submitted to the European Medicines Agency (“EMA”) and is being reviewed under EMA’s centralized review procedure, which allows review of a single marketing authorization application. If the MAA is approved, it would authorize the product to be marketed in all European Union (“EU”) member states and European Economic Area countries. The European Commission has granted narsoplimab designation as an orphan medicinal product for treatment in hematopoietic stem cell transplantation. For commercialization of YARTEMLEA outside the U.S., we are evaluating potential partnerships, including broad ex-U.S. and regional collaborations.

Sale of Zaltenibart

On November 25, 2025, we completed a transaction (the “Transaction”) pursuant to the APLA between Omeros and Novo Nordisk, dated October 10, 2025, in which Novo Nordisk received exclusive global rights in all indications to develop and commercialize our lead investigational MASP-3 inhibitor, zaltenibart (formerly OMS906), and certain related compounds and products. Zaltenibart is a first-in-class, late-stage clinical humanized monoclonal antibody targeting MASP-3, the most upstream and key activator of the alternative pathway of the complement system. Zaltenibart has shown multiple potential advantages over other alternative pathway inhibitors in development and on the market.

At the closing of the Transaction, we received an upfront cash payment of $240.0 million. In addition, we are eligible to receive (i) up to $510.0 million in one-time milestone payments upon the first achievement by Novo Nordisk or its affiliates or sublicensees of each of the development and approval milestone events as set forth in the APLA and (ii) up to $1.3 billion in one-time milestone payments upon the first achievement by Novo Nordisk or its affiliates or sublicensees of certain sales-based milestone events as set forth in the APLA. We are also eligible under the APLA to receive tiered royalties on annual net sales of products at percentage rates ranging from high single digit to high teens, subject to reduction in certain circumstances, as set forth in the APLA. In total, we are eligible to receive up to an additional $1.8 billion in potential development and commercial milestones, plus tiered royalties on net sales.

Pursuant to the APLA, we sold and transferred, and Novo Nordisk purchased, zaltenibart and certain related assets, and the parties agreed to grant and receive certain intellectual property licenses to facilitate the continued development and commercialization activities of both companies. We retain rights to our MASP-3 small-molecule program unrelated to zaltenibart, including the ability to develop and commercialize small-molecule MASP-3 inhibitors, across a range of therapeutic areas, including, but not limited to, ophthalmology, neurology, gastrointestinal disorders, dermatology, musculoskeletal diseases and oncology. We also retain rights to our “grandfathered” MASP-3 antibodies, with temporal and indication restrictions on commercialization and for use in advancing our small-molecule therapeutics.

In accordance with the APLA, at the closing of the Transaction, Omeros and Novo Nordisk entered into a transition services agreement (the “Transition Services Agreement”) pursuant to which we are providing certain transition services to Novo Nordisk to facilitate the transfer of the acquired assets and liabilities under the APLA and to provide for the continued operation of relevant studies and program activities during the applicable term. Subject to certain exceptions and limitations, Novo Nordisk reimburses us for costs and expenses we incur under the Transition Services Agreement, including third-party costs and expenses, costs associated with delivery of transition services by Omeros personnel on an hourly basis at rates specified in the Transition Services Agreement, and for our inventories of zaltenibart drug substance and product.

Other Development Programs

Our lectin pathway program also includes OMS1029, our long-acting antibody targeting MASP-2. We have completed Phase 1 clinical trials evaluating both single-ascending and multiple ascending doses of OMS1029. Results of these studies support once-quarterly dosing administered either intravenously or subcutaneously. OMS1029 has been well tolerated to date with no safety concerns identified. We are working to finalize selection of an indication and initiate Phase 2 clinical development of OMS1029. In addition, we have selected a development candidate for our MASP-2 small molecule program, which is advancing to Investigational New Drug (“IND”)-enabling studies targeting once-daily oral administration.

Our PDE7 inhibitor program, which we refer to as OMS527, comprises multiple PDE7 inhibitor compounds and is based on our discoveries of previously unknown links between PDE7 and any addiction or compulsive disorder, and between PDE7 and any movement disorder. In April 2023, we were awarded a grant from the National Institute on Drug Abuse (“NIDA”), to develop an orally administered PDE7 inhibitor compound for the treatment of cocaine use disorder. NIDA awarded the grant to us for a total of $6.24 million over three years, of which we have claimed and received $2.3 million of funding to date. FDA subsequently requested additional nonclinical information prior to initiating the clinical in-patient study. Following a meeting with FDA to discuss that request, we are working with FDA to streamline the path to initiate the in-patient clinical trial, which is targeted for initiation by year-end 2026.

We also have various programs in preclinical research and development. We continue to progress preclinical studies within our novel oncology program, which is focused on developing novel, proprietary large molecule therapeutics designed to selectively target and kill dividing cancer cells. We have completed selection of a drug development candidate, and IND-enabling studies are underway for this program, which we refer to as OncotoX-AML. Acute myeloid leukemia (“AML”), an aggressive and highly fatal bone marrow and blood cancer, is the lead indication for development.

We are also advancing our targeted complement activating therapy (“T-CAT”) platform: a new class of recombinant antibodies intended for broad action against pathogens, including bacteria, fungi, viruses, and parasites. T-CAT is designed to harness complement activation to kill pathogens directly, which represents a novel approach to infectious disease treatment. Our initial focus is on T-CAT’s potential against multidrug-resistant organisms.

Basis of Presentation

Our condensed consolidated financial statements include the financial position and results of operations of Omeros and our wholly owned subsidiaries. All inter-company transactions have been eliminated. The accompanying condensed consolidated financial statements reflect all adjustments, consisting of normal recurring adjustments and non-recurring adjustments, considered necessary for the fair presentation of such information. Our financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”).

Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Significant items subject to such estimates include revenue recognition and the valuations of the OMIDRIA contract royalty asset, the OMIDRIA royalty obligation, and the embedded derivatives associated with our debt. We base our estimates on historical experience and on various other factors that we believe are reasonable under the circumstances; however, actual results could differ from these estimates.