Wedoany.com Report-Dec.25, Omeros Corporation announced on Wednesday that the U.S. Food and Drug Administration has approved its drug narsoplimab-wuug, branded as Yartemlea, for the treatment of transplant-associated thrombotic microangiopathy (TA-TMA) in adults and children two years of age and older.

This marks the first FDA-approved therapy specifically indicated for TA-TMA, a serious complication that can occur after stem cell transplants, especially those using donor cells.

TA-TMA develops when damaged blood vessels and an overactive immune response lead to inflammation and small blood clots. These clots can affect organs, particularly the kidneys, and in severe cases cause life-threatening damage.

Omeros shares rose nearly 70% in morning trading following the approval announcement.

Yartemlea is a monoclonal antibody that targets and blocks the MASP-2 protein, a key component of the immune system's complement pathway involved in the condition.

The approval is based on data from a 28-patient clinical trial in individuals with high-risk TA-TMA receiving the drug as first-line treatment. The trial showed a 61% survival rate among participants.

The FDA had previously issued a complete response letter in 2021, indicating that additional evidence was needed to establish clear treatment benefit. Omeros provided further data to address those concerns.

H.C. Wainwright analyst Brandon Folkes noted that prior to this decision, Omeros had been viewed as a "show-me" story due to the long review process. The approval removes that uncertainty and allows attention to shift toward the commercial potential of Yartemlea and the company's wider pipeline.

Omeros expects Yartemlea to become available for patients in January 2026. The company did not immediately respond to requests for information on the drug's pricing.

A decision from the European Medicines Agency is anticipated in mid-2026, which would support potential availability in European markets.

Currently, no other treatment carries specific approval for TA-TMA. Some physicians use AstraZeneca's Soliris, approved for a related condition called atypical hemolytic uremic syndrome, on an off-label basis for TA-TMA cases.

This approval provides a targeted option for patients and healthcare providers managing this transplant complication. It addresses an unmet medical need in both pediatric and adult populations undergoing stem cell transplantation.

Omeros continues to advance its research in complement-mediated disorders, with Yartemlea representing an important milestone in delivering specialized therapies for rare and severe conditions.

The development highlights progress in addressing challenges associated with stem cell transplantation and improving outcomes for patients at risk of organ damage from immune-related complications.