Pivotal trial of OMS 721 shows efficacy in hematopoietic stem cell transplant-associated thrombotic microangiopathy.- Omeros

Omeros reports an update on clinical data from its pivotal trial of OMS 721 (narsoplimab) in the treatment of hematopoietic stem cell transplant-associated thrombotic microangiopathy (HSCT-TMA), markedly exceeding the FDA-agreed threshold for the primary efficacy endpoint. While an overview of preliminary data submitted to FDA was made public on December 4, 2019, all patients have now completed treatment and trial enrollment has been closed. The efficacy threshold agreed with FDA, the updated results from the 28-patient trial, and highlights of the recent FDA meetings are the following: 15% is the FDA-agreed efficacy threshold for the primary endpoint (i.e. the complete response rate [CRR]) in the clinical trial. The CRR for the study population, and the lower limit of the 95 percent confidence interval (95% CI), significantly exceed the efficacy threshold. 54 percent CRR (95% CI = 34 percent to 72 percent, p-value < 0.0001) in patients who received at least one dose of narsoplimab. 65 percent CRR (95% CI = 43 percent to 84, p-value < 0.0001) in patients who received the protocol-specified narsoplimab treatment of at least 4 weeks of dosing. The most commonly reported adverse events in the trial were diarrhea, nausea, vomiting, hypokalemia, neutropenia and fever – all common in stem-cell transplant patients. Six deaths occurred during the trial. These were due to sepsis, progression of the underlying disease, and graft-versus-host disease, all common causes of death in this patient population. In recent meetings with FDA focused on clinical as well as chemistry, manufacturing and controls (CMC) data, FDA confirmed important aspects of Omeros’ rolling Biologics License Application (BLA) for narsoplimab in HSCT-TMA. The BLA continues on its clear path to completion.