Omeros tanks as narsoplimab BLA as HSCT-TMA therapy rejected

Seattle, USA-based biotech Omeros Corporation (Nasdaq: OMER) saw its shares plummet 38% to $8.54 on Friday, as it revealed that the US Food and Drug Administration notified the company that its marketing application for narsoplimab could not be approved.

As part of the FDA’s ongoing review of the company’s Biologics License Application (BLA) for narsoplimab in the treatment of hematopoietic stem cell transplant-associated thrombotic microangiopathy (HSCT-TMA), the regulator has identified deficiencies that preclude discussion of labeling and post-marketing requirements/commitments at this time. The FDA stated that the notification does not reflect a final decision on the information under review.

If approved, Narsoplimab had been expected to be a strong competitor to Alexion Pharmaceuticals’ Soliris (eculizumab) as the current off-label standard of care (SOC) for HSCT-TMA, as it has demonstrated a superior response rate in patients. GlobalData had previously forecast narsoplimab sales to reach $575 million globally in HCST-TMA by 2027.