Novo Nordisk announced it will acquire exclusive global rights to develop and commercialize zaltenibart, an investigational monoclonal antibody for rare blood and kidney disorders, from Seattle-based biopharmaceutical company Omeros Corporation. The asset purchase and license agreement is valued at up to $2.1 billion, with Omeros eligible for $340 million in upfront and near-term milestone payments, plus additional development and commercial milestones and tiered royalties on net sales.
The announcement sent Omeros shares soaring more than double on Wednesday, while Novo Nordisk shares gained 0.8%. The transaction is expected to close in the fourth quarter of 2025, subject to regulatory approvals and other customary closing conditions.
Zaltenibart Shows Promise in Rare Blood Disorders
The agreement follows positive trial data for zaltenibart in paroxysmal nocturnal hemoglobinuria (PNH), a rare, acquired blood disorder. Zaltenibart (OMS906) is a 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.
"Novo Nordisk is in a strong position to build on the work done by Omeros to maximize the value of this asset and develop zaltenibart into a differentiated and potentially best-in-class treatment approach for a number of rare blood and kidney disorders," said Martin Holst Lange, chief scientific officer and executive vice president of research and development at Novo Nordisk.
MASP-3 is responsible for converting complement pro-factor D to its active form, factor D. With low systemic circulation compared to other alternative pathway proteins and slow circulation clearance, MASP-3 is considered a highly attractive therapeutic target. Unlike inhibitors of C3 or C5, MASP-3 inhibition preserves the classical pathway function, which is critical to vaccine-induced immunity and defense against infections.
Broad Therapeutic Potential Across Multiple Indications
Zaltenibart has potential applications across a broad range of therapeutic areas and indications beyond PNH, including renal diseases such as immunoglobulin A nephropathy (IgAN), C3 glomerulopathy and atypical hemolytic uremic syndrome, and other immune and complement-driven disorders.
Following the transaction closure, Novo Nordisk aims to initiate a global phase 3 program for zaltenibart in PNH and explore further development in a range of other rare blood and kidney disorders. The Danish pharmaceutical giant plans to launch a late-stage phase 3 study for zaltenibart in paroxysmal nocturnal hemoglobinuria once the deal is complete.
Strategic Expansion in Rare Disease Portfolio
The acquisition aligns with Novo Nordisk's strategic commitment to broaden its pipeline of rare-disease drugs. The company previously announced plans to invest $1.2 billion in new production facilities in Denmark late last year.
"With zaltenibart, we have a compelling opportunity to help a significant number of people living with rare blood and kidney disorders in the future and support our leadership ambition in this space," said Ludovic Helfgott, executive vice president of Product and Portfolio Strategy at Novo Nordisk. "This agreement will build on Novo Nordisk's heritage and enhance our existing Rare Disease portfolio with potential to drive additional growth in this business area."
Under the agreement, Omeros retains certain rights to its preclinical MASP-3 programs unrelated to zaltenibart, including the ability to develop and commercialize small-molecule MASP-3 inhibitors with limited indication restrictions. The deal represents a significant validation of Omeros' complement-focused drug development approach and provides substantial financial resources for the company's continued operations and pipeline development.
