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FDA Wants Deficiencies in Application Addressed Before Approving Omeros HSCT-TMA Therapy

October 1, 2021

The U.S. Food and Drug Administration notified Omeros that before it would approve narsoplimab, the company’s experimental for the treatment of hematopoietic stem cell transplant-associated thrombotic microangiopathy, it would need to address deficiencies in its application.

The company said the agency did not provide specific details of the deficiencies in its notification, but in a meeting held on September 30, 2021, FDA expressed its intention to work with Omeros to resolve any issues as expeditiously as possible.

The company said it does not expect resolution to occur by the October 17, 2021 target action date under the Prescription Drug User Fee Act. That sent shares of Omeros down more than 40 percent to a new 52-week low of $7.51 in early trading.

Hematopoietic stem cell transplant-associated thrombotic microangiopathy (HSCT-TMA) is a rare and potentially deadly condition that occurs in up to 30 percent of patients who have received a hematopoietic stem cell transplant (HSCT).

Narsoplimab is a human monoclonal antibody targeting mannan-binding lectin-associated serine protease-2 (MASP-2), the effector enzyme of the lectin pathway of the complement system. The lectin pathway is one of the principal pathways of complement and is activated primarily by tissue damage and microbial infection. Importantly, inhibition of MASP-2 does not appear to interfere with the classical complement pathway, a critical component of the acquired immune response to infection. This drug is designed to prevent complement-mediated inflammation and endothelial damage while leaving intact the respective functions of the other pathways of innate immunity.

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. The BLA for narsoplimab in HSCT-TMA was accepted for filing in January 2021 under FDA’s Priority Review program.

Omeros is evaluating potential next steps as it awaits additional information from FDA and plans to obtain FDA approval for narsoplimab in HSCT-TMA, a frequently lethal complication of HSCT for which there is no FDA-approved treatment, as quickly as possible.

Author: Rare Daily Staff

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