Omeros Corporation Shares Surge 73%

Shares of Omeros (NASDAQ:OMER) Corporation surged 73% early Thursday following the announcement of positive survival data from an independent statistical analysis for its treatment, narsoplimab, in patients with hematopoietic stem cell transplant-associated thrombotic microangiopathy (TA-TMA). The analysis demonstrated a significant over 3-fold reduction in the risk of mortality for patients treated with narsoplimab compared to a control group.

The pivotal trial, OMS721-TMA-001, compared overall survival in 28 TA-TMA patients treated with narsoplimab to more than 100 high-risk TA-TMA patients in an external control registry who did not receive the treatment. The results showed a hazard ratio of 0.32, indicating a 68% lower risk of death for the narsoplimab-treated group, with a p-value less than 0.00001, which is considered statistically significant.

Omeros is now preparing to resubmit a Biologics License Application (BLA) to the FDA for narsoplimab, aiming to make it the first approved therapeutic for TA-TMA, a life-threatening complication of stem cell transplantation. The company received FDA recommendations on the statistical analysis plan last month and, following the positive outcome, plans to file the corresponding European marketing authorization application in the second quarter of 2025.

The analysis was conducted by an independent external statistical group and agreed upon with the FDA. It adjusted for immortal time bias and took into account demographics, diagnostic criteria, baseline characteristics, underlying diseases, conditioning regimens, and transplant procedures. The two cohorts were deemed to have similar risk profiles for death as defined by an international expert panel.

Dr. Alessandro Rambaldi, Professor of Hematology at the University of Milan, highlighted the impressive benefits of narsoplimab in high-risk patients, noting the substantial need for an approved therapeutic in this area. Additional analyses, including a comparison of survival data from the global narsoplimab expanded access program to the registry, are underway and are expected to support the primary analysis.

Narsoplimab, which targets the lectin pathway’s effector enzyme MASP-2, has been well tolerated across various clinical trials with no safety concerns raised. The results from the primary analysis have encouraged Omeros to expedite the process of making narsoplimab widely available to patients and physicians, with manuscripts for peer-reviewed publication planned for the coming year.

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