FDA rejects Omeros transplant drug

Oct. 18, 2021

Omeros Corporation revealed that the company received a Complete Response Letter (CRL) from the U.S. FDA regarding its Biologics License Application (BLA) for its lead candidate, narsoplimab, for treatment of transplant complications.

In the CRL, FDA expressed difficulty in estimating the treatment effect of narsoplimab in hematopoietic stem cell transplant-associated thrombotic microangiopathy (HSCT-TMA) and asserted that additional information will be needed to support regulatory approval. There were no chemistry, manufacturing and controls (CMC), safety, or non-clinical issues precluding approval raised in the CRL.

This likely comes as no surprise to the Seattle, Washington-based biopharma. Earlier this month, Omeros revealed that the FDA had found deficiencies in its filing for approval of narsoplimab that "preclude discussion of labeling and post-marketing requirements/commitments at this time." The agency had expressed its intention to work with Omeros to resolve any issues as expeditiously as possible, but the company didn't expect that resolution to come by the October 17 PDUFA date — and it seems they were correct.

The drug — a MASP-2 inhibitor — is being tested in transplant-associated thrombotic microangiopathy, a fatal complication of stem cell transplants. Narsoplimab is the first drug candidate submitted to FDA for approval in HSCT-TMA. It has Breakthrough Therapy and Orphan designations in both HSCT-TMA and IgA nephropathy.

Omeros said it plans to request a Type A meeting as soon as possible with FDA to discuss the CRL and determine the most expeditious path forward for the approval of narsoplimab in the treatment of HSCT-TMA.