Novo Nordisk Acquires Omeros' PNH Drug Zaltenibart in $2.1B Deal

Novo Nordisk has entered into a $2.1 billion agreement with Omeros Corporation to acquire zaltenibart, a MASP-3 inhibitor being developed for the treatment of paroxysmal nocturnal hemoglobinuria (PNH) and other rare blood and kidney disorders. The deal, announced on October 15, 2025, marks a significant development in the rare disease drug market and showcases Novo Nordisk's strategic expansion into specialized therapeutic areas.

Deal Structure and Financial Details

Under the terms of the agreement, Novo Nordisk will make upfront and near-term milestone payments totaling $340 million to Omeros. The Seattle-based biopharma company stands to receive up to $2.1 billion in total, including royalties on potential future sales of zaltenibart. This acquisition comes at a crucial time for Omeros, following recent setbacks in its pipeline, including an FDA rejection of its anti-MASP-2 antibody narsoplimab.

Zaltenibart's Potential and Development Plans

Zaltenibart, an investigational MASP-3 inhibitor, has shown promise in the treatment of PNH, a rare blood disorder. In phase 2 trials, the drug demonstrated "sustained clinically meaningful improvements in both hemoglobin and absolute reticulocyte count and prevented both intravascular and extravascular hemolysis." Novo Nordisk plans to initiate a global phase 3 program for zaltenibart in PNH and explore its potential in other rare blood and kidney disorders.

Martin Holst Lange, Novo Nordisk's chief scientific officer, highlighted zaltenibart's "novel mode of action that could offer several advantages over other treatments for complement-mediated diseases." The Danish pharmaceutical company aims to leverage its resources and expertise to position zaltenibart as a potentially best-in-class treatment approach in this therapeutic area.

Market Implications and Competitive Landscape

The PNH market has been dominated by AstraZeneca's C5 inhibitors, Ultomiris and Soliris, acquired through the Alexion takeover in 2020. Zaltenibart's development under Novo Nordisk could potentially challenge this market dominance, offering patients an alternative treatment option with a different mechanism of action and comparable dosing schedule to Ultomiris.

This acquisition aligns with Novo Nordisk's broader strategy of diversifying its portfolio beyond its core areas of diabetes and obesity. The company has recently undergone significant restructuring, including layoffs and the termination of its cell therapy R&D efforts, while simultaneously seeking new opportunities in liver disease and obesity treatment.

For Omeros, the deal provides a much-needed boost following recent setbacks. CEO Gregory Demopulos stated that the company will now focus on "securing approval and commercialization of narsoplimab this quarter and continuing to advance its robust development pipeline."