Novo Nordisk has entered into a licensing agreement with Omeros Corporation for the rights to develop and commercialize zaltenibart, Omeros’ MASP-3 inhibitor, in a deal worth up to $2.1 billion. The agreement grants Novo Nordisk exclusive global rights to the experimental therapy, which is being developed for rare blood and kidney disorders.
The deal includes $340 million in upfront and near-term milestone payments to Omeros, with the remainder tied to future development and commercialization milestones. Omeros will also receive royalties if the drug reaches the market, according to the companies’ joint announcement.
Zaltenibart targets MASP-3, a protein that activates the alternative pathway of the complement system—a group of blood proteins that supports the immune system. The drug has been studied for the treatment of paroxysmal nocturnal hemoglobinuria (PNH), a rare blood disorder in which the immune system attacks and destroys red blood cells and platelets.
Omeros had spent the early months of 2025 preparing for a phase 3 trial of zaltenibart in PNH, after earlier phase 2 results presented at the 2024 American Society of Hematology meeting showed “sustained clinically meaningful improvements in both hemoglobin and absolute reticulocyte count and prevented both intravascular and extravascular hemolysis.” However, in May, the company announced a temporary pause in the program due to the need to manage its available capital and prioritize spending.
At the time, Omeros stated it was “working with our vendors and investigators to ensure that the program is ready to be restarted with as little disruption to the timeline as possible after securing capital.” The company later confirmed that it was seeking potential partners across its portfolio to continue advancing its clinical pipeline.
Novo Nordisk now plans to initiate a global phase 3 program for zaltenibart in PNH and explore additional development opportunities in other rare blood and kidney conditions. The Danish drugmaker also emphasized the therapeutic potential of the MASP-3 inhibitor in complement-mediated diseases. Martin Holst Lange, Novo Nordisk’s chief scientific officer, said the drug has a “novel mode of action that could offer several advantages over other treatments for complement-mediated diseases.”
He added that Novo Nordisk is well-positioned to build on Omeros’ prior work and develop zaltenibart “into a differentiated and potentially best-in-class treatment approach for a number of rare blood and kidney disorders.” The company expects the transaction to close in the fourth quarter of 2025.
The agreement comes amid organizational changes at Novo Nordisk, which is reducing its workforce and scaling back certain research programs, including those in cell therapy, while continuing to expand in areas such as liver disease and obesity.
For Omeros, the deal marks a significant development following recent regulatory challenges. Two months earlier, the FDA had declined to approve Omeros’ anti-MASP-2 antibody narsoplimab for transplant-associated thrombotic microangiopathy.
“With Novo Nordisk driving the success of zaltenibart, Omeros remains focused on securing approval and commercialisation of narsoplimab this quarter and continuing to advance its robust development pipeline,” said Omeros CEO Gregory Demopulos, M.D.
Under the terms of the agreement, Omeros will retain certain rights to its preclinical MASP-3 programs unrelated to zaltenibart, including the option to develop and commercialize small-molecule MASP-3 inhibitors for limited indications.
Novo Acquires Global Rights to Omeros’ Rare Disease Drug Zaltenibart in $2.1 Billion Deal
In a major move to strengthen its rare disease portfolio, Novo Nordisk has announced a landmark agreement to acquire the global rights to Zaltenibart, a late-stage experimental therapy developed by Omeros Corporation. The deal, valued at up to $2.1 billion, underscores Novo’s growing interest in complement-based therapies and its strategic push into specialized treatments for rare blood and kidney disorders.
Under the terms of the agreement, Novo Nordisk will make an upfront payment of $340 million, with the remainder tied to regulatory and commercial milestones. Zaltenibart, a MASP-3 inhibitor, is designed to block a key component of the complement system’s alternative pathway — a mechanism involved in inflammation and tissue damage in several rare and severe diseases.
Omeros has been developing Zaltenibart to treat conditions such as atypical hemolytic uremic syndrome (aHUS) and other complement-driven disorders that currently have limited treatment options. Novo Nordisk’s global reach and expertise in clinical development are expected to accelerate the program’s path toward commercialization, expanding access to patients worldwide.
The acquisition also highlights Novo Nordisk’s broader ambition to diversify beyond diabetes and obesity into high-value therapeutic areas like rare diseases and immunology. Analysts suggest that Zaltenibart could represent a multibillion-dollar opportunity if successful in late-stage clinical trials, positioning Novo as a key competitor in the emerging complement-inhibition market.
