On December 1, 2025 Omeros Corporation (Nasdaq: OMER) reported 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.
Schedule your 30 min Free 1stOncology Demo!
Discover why more than 1,500 members use 1stOncology™ to excel in:
Early/Late Stage Pipeline Development - Target Scouting - Clinical Biomarkers - Indication Selection & Expansion - BD&L Contacts - Conference Reports - Combinatorial Drug Settings - Companion Diagnostics - Drug Repositioning - First-in-class Analysis - Competitive Analysis - Deals & Licensing
Schedule Your 30 min Free Demo!
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.
(Press release, Omeros, DEC 1, 2025, View Source [SID1234661026])