Exhibit 99.1

Omeros Corporation Announces Closing of Asset Purchase and License Agreement with Novo Nordisk for Omeros’ Clinical-Stage MASP-3 Inhibitor Zaltenibart (OMS906)

SEATTLE, WA – December 1, 2025 – Omeros Corporation (Nasdaq: OMER) today announced the closing of the asset sale and licensing transaction between Omeros and Novo Nordisk for the candidate drug zaltenibart (formerly OMS906). 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 – and has shown multiple potential advantages over other alternative pathway inhibitors in development or on the market. The transaction was completed pursuant to an asset purchase and license agreement that was announced on October 15, 2025.

Omeros is eligible to receive upfront and near-term milestone payments up to $340.0 million, of which the upfront amount of $240.0 million was paid in cash at closing. In total, Omeros is eligible to receive up to $2.1 billion including potential development and commercial milestones, plus tiered royalties on net sales.

Novo Nordisk is strongly positioned to develop zaltenibart into a differentiated and potentially best-in-class treatment approach for a number of rare blood and kidney disorders, maximizing the opportunity to help people living with these diseases in the future and supporting the company’s leadership ambition in this space. Omeros retains rights to its MASP-3 small-molecule program unrelated to zaltenibart, including the ability to develop and commercialize small-molecule MASP-3 inhibitors with limited restrictions on indications.

At the closing, Omeros prepaid the entire $67.1 million principal amount outstanding under its senior secured term loan, along with a related pre-payment premium, accrued and unpaid interest, and expenses. The prepayment resulted in the termination of the senior secured credit agreement between Omeros and the term loan lenders and the release in full of all liens and covenants thereunder, including the $25.0 million minimum liquidity covenant. Omeros expects that the remaining proceeds from the closing payment will be sufficient to repay at or prior to maturity the remaining $17.1 million principal balance on its 2026 Convertible Notes and fund more than 12 months of operations, including the anticipated U.S. launch of narsoplimab for the treatment of transplant-associated thrombotic microangiopathy (TA-TMA).

About zaltenibart

Zaltenibart (OMS906) is an investigational humanized monoclonal antibody that selectively targets mannan-binding lectin-associated serine protease-3 (MASP-3), the key and most upstream activator of the alternative pathway of the complement system and a critical component of innate immunity involved in host defense and immune regulation. By inhibiting MASP-3, zaltenibart is designed to address complement-mediated diseases driven by alternative pathway dysregulation.

MASP-3 is responsible for converting complement pro-factor D to its active form, factor D. With low systemic levels compared to other alternative pathway proteins and slow clearance from circulation, MASP-3 is considered a highly attractive therapeutic target. Unlike inhibitors of C3 or C5, MASP-3 inhibition preserves classical pathway activity, which is critical to vaccine-induced immunity and defense against infections. Moreover, MASP-3 is not believed to be an acute-phase reactant, potentially offering another significant advantage for MASP-3 inhibitors like zaltenibart.

Zaltenibart has potential applications across a broad range of therapeutic areas and indications, including paroxysmal nocturnal hemoglobinuria (PNH), renal diseases such as immunoglobulin A nephropathy (IgAN), C3 glomerulopathy and atypical hemolytic uremic syndrome, and other immune and complement-driven disorders.

About Omeros Corporation

Omeros is a clinical-stage biopharmaceutical company focused on discovering, developing, and commercializing first-in-class small-molecule and protein therapeutics for both large-market and orphan diseases, with a particular emphasis on complement-mediated diseases, cancers, and addictive or compulsive disorders. Omeros’ lead MASP-2 inhibitor narsoplimab targets the lectin pathway of complement and is under regulatory review by both the U.S. Food and Drug Administration and the European Medicines Agency for the treatment of hematopoietic stem cell transplant-associated thrombotic microangiopathy. OMS1029, a long-acting MASP-2 inhibitor, has successfully completed Phase 1 clinical trials. Pursuant to a recently announced agreement, Novo Nordisk acquired global rights to zaltenibart (formerly OMS906), a MASP-3 inhibitor in clinical development for paroxysmal nocturnal hemoglobinuria and other alternative pathway indications, including associated intellectual property and related assets. Omeros is entitled to receive cash milestone payments upon Novo Nordisk’s achievement of certain development, approval, and sales-based milestones related to zaltenibart and certain related therapeutic antibodies, as well as royalties on net sales of commercialized products. Omeros’ pipeline also includes OMS527, a phosphodiesterase 7 inhibitor in clinical development for cocaine use disorder, fully funded by the National Institute on Drug Abuse, as well as a growing portfolio of novel molecular and cellular therapeutic programs for oncology. For more information about Omeros and its programs, visit www.omeros.com.

Forward-Looking Statements

This press release contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934, which are subject to the “safe harbor” created by those sections for such statements. All statements other than statements of historical fact are forward-looking statements, which are often indicated by terms such as “anticipate,” “believe,” “could,” “estimate,” “expect,” “goal,” “intend,” “likely,” “look forward to,” “may,” “objective,” “plan,” “potential,” “predict,” “project,” “should,” “slate,” “target,” “will,” “would,” and similar expressions and variations thereof. Forward-looking statements, including statements regarding the anticipated review process and timing of regulatory action on our BLA for narsoplimab in the United States and/or the marketing authorization application for narsoplimab in Europe, prospects for obtaining FDA or EMA approval of narsoplimab in any indication and for successful commercial launch following any such approval, plans and expectations regarding the initiation, resumption and conduct of preclinical and clinical studies, including the availability of data therefrom, our ability to consummate licensing, partnering or other transactions and the benefits, if any, we would receive from any such transactions, expectations regarding the sufficiency and availability of our capital resources to fund current and planned operations, including the potential commercialization of narsoplimab if it is approved by FDA or the EMA, plans for development of zaltenibart or other products under the asset purchase and license agreement, and the potential therapeutic benefits of zaltenibart and its commercial prospects, are based on management’s beliefs and assumptions and on information available to management only as of the date of this press release. Omeros’ actual results could differ materially from those anticipated in these forward-looking statements for many reasons, including, without limitation, unfavorable or unexpected regulatory conclusions or interpretations related to the clinical data, external registry data, statistical analyses or other information and data included in the narsoplimab BLA, inability to respond satisfactorily to information requests during regulatory review of the narsoplimab BLA or MAA, potential differences between the diagnostic criteria used in our pivotal trial and in the external registry, and whether FDA and the EMA determine the registry used in our statistical analysis is sufficiently representative of TA-TMA patients, unanticipated or unexpected outcomes or requirements of regulatory processes in relevant jurisdictions, our financial condition and results of operations, including our ability to raise additional capital for our operations or complete other transactions on favorable terms or at all, regulatory processes and oversight, challenges associated with manufacture or supply of our products to support clinical trials, regulatory inspections and/or commercial sale following any marketing approval, changes in reimbursement and payment policies by government and commercial payers or the application of such policies, intellectual property claims, competitive developments, litigation, and the risks, uncertainties, and other factors described under the heading “Risk Factors” in our Annual Report on Form 10-K filed with the Securities and Exchange Commission on March 31, 2025 and in subsequently-filed Quarterly Reports on Form 10-Q. Given these risks, uncertainties, and other factors, you should not place undue reliance on these forward-looking statements, and we assume no obligation to update these forward-looking statements, whether as a result of new information, future events or otherwise, except as required by applicable law.

Jennifer Cook Williams
Cook Williams Communications, Inc.
Investor and Media Relations
IR@omeros.com

Exhibit 99.2

Omeros Corporation 

Unaudited Pro Forma Condensed Consolidated Financial Statements

On November 25, 2025, Omeros Corporation (“Omeros” or the “Company”) completed the closing of the previously announced transaction under the Asset Purchase and License Agreement, dated October 10, 2025 (the “APLA”) with Novo Nordisk Health Care AG (“Novo Nordisk”), pursuant to which Novo Nordisk received exclusive global rights in all indications to develop and commercialize zaltenibart (OMS906), Omeros’ lead human monoclonal antibody targeting mannan-binding lectin-associated serine protease-3 (“MASP-3”), certain related monoclonal antibodies and antigen-binding fragments (collectively, the “Compounds”), and related pharmaceutical products (the “Products”). Under the APLA, Omeros sold and transferred, and Novo Nordisk purchased and assumed, certain assets related to the Compounds and Products, including key patents and other intellectual property.  The parties also granted and received certain intellectual property licenses in order to facilitate the continued development and commercialization activities of both companies (the “Transaction”). 

At the closing of the Transaction (the “Closing”), Omeros received an upfront cash payment of $240.0 million. As contemplated by the Credit and Guarantee Agreement, dated June 3, 2024 (the “Credit Agreement”), among the Company, the various lenders party thereto, and Wilmington Savings Fund Society, FSB, as Administrative Agent and Collateral Agent, a portion of the upfront cash payment was applied to fully repay the $67.1 million outstanding term loan under the Credit Agreement (the “Term Loan Repayment”), a $3.4 million mandatory prepayment premium, incurred interest of $2.0 million and approximately $0.1 million of transaction related expenses. The Term Loan Repayment resulted in the termination of the Credit Agreement and release in full of all liens and covenants thereunder including the covenant requiring the Company to maintain at all times a minimum of $25.0 million of unrestricted cash, cash equivalents and short-term investments. Upon the occurrence of such events, the Credit Agreement was terminated.

The unaudited pro forma condensed consolidated balance sheet as of September 30, 2025 gives effect to the Transaction and Term Loan Repayment as if they had occurred on September 30, 2025. The unaudited pro forma consolidated financial statements of operations and comprehensive income (loss) for the year ended December 31, 2024 and nine months ended September 30, 2025 give effect to the Transaction and Term Loan Repayment as if they had occurred on January 1, 2024.

The unaudited pro forma condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements as of December 31, 2024 and the notes thereto contained in the Company’s Annual Report on Form 10-K filed on March 31, 2025, as amended, and the unaudited condensed consolidated financial statements as of September 30, 2025 contained in the Company’s Quarterly Report on Form 10-Q filed on November 13, 2025.

The unaudited pro forma condensed consolidated financial statements are presented based on information currently available and are provided for informational purposes only. They are not intended to represent what the Company’s condensed consolidated statements of operations and comprehensive income (loss) and balance sheet actually would have been had the Transaction and Term Loan Repayment occurred on the applicable date indicated above, nor do they reflect all actions that may be undertaken by the Company following Closing. In addition, these unaudited pro forma condensed consolidated financial statements are not necessarily indicative of the Company’s results of operations and financial position for any future period.

The “Historical Omeros (as reported)” column in the unaudited pro forma condensed consolidated financial statements reflects the Company’s historical condensed consolidated financial statements for the periods presented and does not reflect any adjustments related to the Transaction or the Term Loan Repayment.

The “Asset Sale and License Adjustments” column in the unaudited pro forma condensed consolidated financial statements was based on available information and assumptions that reflects the impacts of events directly attributable to the Transaction which management believes are reasonable and factually supportable.

Likewise, the “Term Loan Repayment” column in the unaudited pro forma condensed consolidated financial statements was based on available information and assumptions that reflects the impacts of events directly attributable to the Term Loan Repayment which management believes are reasonable and factually supportable.

Basis of Pro Forma Presentation

The accompanying unaudited pro forma condensed consolidated financial statements of Omeros were prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) and Article 11 of Regulation S-X and are based on the historical consolidated financial information of the Company. The condensed consolidated financial information has been adjusted in the accompanying pro forma condensed consolidated financial statements to give effect to both the disposition of the Company’s clinical-stage complement-targeted therapeutic candidate, zaltenibart, and the Term Loan Repayment under the Credit Agreement.

Adjustments to the Pro Forma Condensed Consolidated Financial Statements

Explanations of the adjustments to the unaudited pro forma condensed consolidated financial statements are as follows:

a.    Net proceeds from the Transaction reflects gross consideration of $240.0 million after deducting estimated transaction fees of $2.3 million.

b.    Derecognition of the transaction costs which were captured through accounts payable and accrueds as of September 30, 2025, which are paid from gross proceeds of the Transaction. The Company currently does not anticipate any income tax expense as it has sufficient net operating losses and other tax attributes for which valuation allowances were previously established that can be utilized to cover the net gain on the sale.

c.     Repayment of principal outstanding under the Credit Agreement of $67.1 million, a prepayment premium of $3.4 million, incurred interest of $2.0 million and approximately $0.1 million of transaction related expenses as of the Closing.

d.    Unwinding of accrued interest on the balance sheet as of September 30, 2025 of $0.7 million which was paid at Closing. 

e.     Comprised of the following: (1) repayment of principal outstanding under the Credit Agreement of $67.1 million, (2) derecognition of the unamortized premium of approximately $18.8 million related to marking-to-market the term debt to fair market value at the acquisition date, net of issuance costs and (3) derecognition of the associated embedded derivative liability of $1.6 million.

f.     Non-recurring estimated net gain on extinguishment of the term debt is comprised of eliminating the following: $18.8 million of unamortized debt premium and issuance costs and $1.6 million of the term debt embedded derivative liability reflected on our September 30, 2025 balance sheet, partially offset by a prepayment penalty expense of $3.4 million, additional interest expense incurred after September 30, 2025 of $1.3 million, which is net of what was accrued and previously expensed as of September 30, 2025, and transaction related expenses of approximately $0.1 million.

g.    Derecognition of OMS906 program costs which otherwise would not have been incurred if the Closing occurred on January 1, 2024. 

h.    Non-recurring upfront proceeds from the sale of zaltenibart to Novo Nordisk of $240.0 million less estimated transaction costs of approximately $1.2 million, which is net of what was accrued and previously expensed as of September 30, 2025.

i.     To reflect the elimination of the term debt interest expense, including amortization of debt premium and capitalized debt issuance costs, which otherwise would not have been incurred if the Closing occurred on January 1, 2024.

j.     Derecognition of a $1.8 million loss on the fair value remeasurement of the term debt embedded derivative.