Omeros is a commercial-stage biotechnology company focused on therapeutics that target the complement system, a group of immune proteins whose dysregulation drives serious diseases. Omeros' lead product is YARTEMLEA (narsoplimab), a monoclonal antibody that inhibits MASP-2, the key enzyme of the lectin pathway of complement. YARTEMLEA received FDA approval in December 2025 as the first and only approved treatment for hematopoietic stem cell transplant-associated thrombotic microangiopathy (TA-TMA), a life-threatening complication following stem cell transplantation. Because YARTEMLEA selectively blocks the lectin pathway rather than the full complement system, it preserves patients' ability to fight infection — a key advantage over the off-label C5 inhibitors historically used for TA-TMA. Omeros is commercializing YARTEMLEA directly in the U.S. through a targeted sales force, focusing on the roughly 175 stem cell transplant centers in the U.S. Beyond YARTEMLEA, Omeros has a pipeline of complement-targeted programs, including OMS1029, a next-generation long-acting MASP-2 antibody for chronic indications, and narsoplimab in planned Phase 2 trials for ARDS. In November 2025, Omeros sold global rights to zaltenibart, a MASP-3 inhibitor in Phase 3 development for a rare blood disorder, to Novo Nordisk for $240M upfront plus up to $1.8B in milestones and royalties. Omeros also has early-stage oncology and infectious disease programs in development. Omeros outsources drug manufacturing to contract manufacturers.