Danish pharmaceutical giant Novo Nordisk has dramatically expanded its footprint in the rare disease sector with a landmark asset purchase and licensing agreement worth up to $2.1 billion for Omeros Corporation’s experimental drug, zalteni bart. This strategic move, centered on a promising MASP-3 inhibitor for rare blood and kidney disorders, not only strengthens Novo Nordisk’s pipeline but also injects significant capital into Omeros, setting the stage for profound long-term impacts on both companies and the broader biopharmaceutical investment landscape.
In a significant move reshaping the rare disease biopharmaceutical landscape, Novo Nordisk announced a definitive asset purchase and license agreement with Omeros Corporation for the clinical-stage drug candidate zalteni bart (formerly OMS 906). This landmark deal, valued at up to $2.1 billion, grants Novo Nordisk exclusive global rights to develop and commercialize zalteni bart for all indications, specifically targeting rare blood and kidney disorders. The announcement, made on October 15, 2025, underscores Novo Nordisk’s strategic commitment to diversifying its portfolio beyond its dominant diabetes and obesity franchises, while providing Omeros with substantial financial resources to propel its other pipeline assets. This transaction is anticipated to close in the fourth quarter of 2025, pending customary regulatory approvals.
The Asset: Zalteni Bart – A New Hope for Complement-Mediated Disorders
At the heart of this billion-dollar acquisition is zalteni bart, an investigational humanized monoclonal antibody designed to selectively inhibit mannan-binding lectin-associated serine protease-3 (MASP-3). MASP-3 is recognized as the key and most upstream activator of the alternative pathway of the complement system, a crucial part of the innate immune system involved in host defense and immune regulation. Dysregulation of this pathway is implicated in a multitude of rare diseases.
What makes zalteni bart particularly compelling for investors and patients alike is its novel mode of action and best-in-class potential. Unlike inhibitors of C3 or C5, MASP-3 inhibition preserves the classical pathway function, which is vital for vaccine-induced immunity and defense against infections. Furthermore, MASP-3 is not believed to be an acute-phase reactant, offering a potential advantage over other alternative pathway inhibitors. Clinical development has shown positive Phase 2 data in paroxysmal nocturnal hemoglobinuria (PNH), a rare acquired blood disorder, with zalteni bart demonstrating an acceptable safety profile and being well tolerated across trials, as detailed in a joint press release by the companies (Novo Nordisk official statement).
The potential applications of zalteni bart extend beyond PNH to a broad range of therapeutic areas, including various renal diseases:
- Immunoglobulin A Nephropathy (IgAN)
- C3 Glomerulopathy
- Atypical Hemolytic Uremic Syndrome (aHUS)
This wide scope positions zalteni bart as a significant long-term growth driver for Novo Nordisk in the rare disease space.
Novo Nordisk’s Vision: Expanding Beyond Diabetes Dominance
For Novo Nordisk, this deal represents a clear signal of its strategic intent to expand its leadership in serious chronic diseases beyond its established dominance in diabetes and more recently, obesity. The company’s heritage in pioneering scientific breakthroughs is now being leveraged to address unmet needs in rare blood and kidney disorders. Martin Holst Lange, Chief Scientific Officer and Executive Vice President of Research & Development at Novo Nordisk, highlighted the drug’s potential: “Zalteni bart has a novel mode of action that could offer several advantages over other treatments for complement-mediated diseases. Novo Nordisk is in a strong position to build on the work done by Omeros to maximise the value of this asset and develop zalteni bart into a differentiated and potentially best-in-class treatment approach for a number of rare blood and kidney disorders,” as reported by Reuters.
This acquisition aligns perfectly with Novo Nordisk’s ambition to become a leader in rare diseases, enhancing its existing portfolio and driving additional growth in this critical business area. The company plans to initiate a global Phase 3 program for zalteni bart in PNH immediately after the transaction closes, further exploring its development in other rare blood and kidney disorders.
Omeros’s Future: Fueling a Diverse Pipeline
For Omeros Corporation, a clinical-stage biopharmaceutical company focused on complement-mediated diseases, cancers, and addictive disorders, the agreement is a substantial financial boost. The deal includes an upfront payment and near-term milestones totaling $340 million, with Omeros eligible to receive up to $2.1 billion in total, encompassing potential development and commercial milestones, plus tiered royalties on net sales.
This infusion of capital provides Omeros with greater flexibility to advance its robust development pipeline. Gregory A. Demopulos, M.D., Chairman and Chief Executive Officer of Omeros, expressed enthusiasm for the partnership: “We look forward to Novo Nordisk leveraging its extensive expertise and global reach to unlock the potential of zalteni bart across alternative pathway indications. With Novo Nordisk driving the success of zalteni bart, Omeros remains focused on securing approval and commercialization of narsoplimab this quarter and continuing to advance its robust development pipeline,” according to the joint press release.
Omeros’s pipeline includes several promising candidates:
- Narsoplimab (MASP-2 inhibitor), currently under regulatory review by the U.S. FDA and European Medicines Agency for hematopoietic stem cell transplant-associated thrombotic microangiopathy.
- OMS 1029, a long-acting MASP-2 inhibitor that has completed Phase 1 trials.
- OMS 527, a phosphodiesterase 7 inhibitor in clinical development for cocaine use disorder, fully funded by the National Institute on Drug Abuse.
Crucially, Omeros retains certain rights to its preclinical MASP-3 programs unrelated to zalteni bart, allowing it to develop and commercialize small-molecule MASP-3 inhibitors with limited indication restrictions. This strategic carve-out ensures Omeros can continue to explore other avenues within the MASP-3 target space.
Investor Outlook: What This Means for Shareholders
From an investment perspective, this deal presents a compelling narrative for shareholders of both companies. For Novo Nordisk, it represents a calculated expansion into a high-growth, high-margin therapeutic area, reducing reliance on its current blockbuster drugs and potentially de-risking its long-term revenue streams. The acquisition of a late-stage, potentially best-in-class asset with a novel mechanism of action aligns with its stated leadership ambitions in rare diseases. Investors will be keenly watching the Phase 3 trial initiation and subsequent development progress of zalteni bart.
For Omeros, the deal provides immediate non-dilutive capital, significantly bolstering its balance sheet and offering validation for its complement-focused research platform. The potential for substantial milestone payments and royalties on net sales offers a long-term revenue stream while allowing the company to concentrate its resources on bringing narsoplimab to market and advancing its diverse preclinical and clinical pipeline. This strategic move could transform Omeros into a more financially stable and focused entity, potentially unlocking greater value for its shareholders as its remaining assets progress.
