Omeros Antibody Improves Overall Survival In Rare Complication After Stem Cell Transplant, Stock Surges

On Thursday, Omeros Corporation OMER announced that an independent statistical group has completed the primary statistical analysis agreed with the FDA for narsoplimab.

Omeros is a first-in-class monoclonal antibody that inhibits the lectin pathway of complement in hematopoietic stem cell transplant-associated thrombotic microangiopathy (TA-TMA).

TA-TMA is a complication in adult and pediatric hematopoietic stem cell transplantation (HSCT).

The analysis compared overall survival in the 28 TA-TMA patients in OMS721-TMA-001, Omeros’ previously conducted pivotal trial for narsoplimab in TA-TMA, to that of more than 100 similarly high-risk TA-TMA patients in an external control registry of HSCT patients who did not receive narsoplimab treatment.

Narsoplimab met its primary endpoint, with OMS721-TMA-001 patients demonstrating clinically meaningful and statistically significant superiority in overall survival – a hazard ratio of 0.32 compared to the TA-TMA registry patients.

Late last month, Omeros announced that it had received FDA’s recommendations on the statistical analysis plan (SAP) for the primary analysis comparing overall survival from the time of first dosing in the 28 narsoplimab-treated TA-TMA patients in the pivotal trial OMS721-TMA-001 to overall survival, adjusted for immortal time bias, of the more than 100 TA-TMA patients in the external control registry, none of whom received narsoplimab.

To date, narsoplimab has been well tolerated and has shown no safety signal of concern across all its clinical trials in various indications.

Given the primary analysis results, we will resubmit the narsoplimab BLA for TA-TMA as quickly as possible, followed by our planned submission of the corresponding European marketing authorization application in the second quarter of 2025.

Additional sensitivity and other analyses are pending and should be available over the next few weeks.

Price Action: OMER stock is up 54.8% at $11.55 at last check Thursday.

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