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Omeros Halts Pursuit of Approval in Rare Kidney Disease After Interim Analysis Shows Drug Fails to Best Placebo

October 16, 2023

Rare Daily Staff

Omeros said topline results from a phase 3 study of its experimental therapy narsoplimab failed to achieve statistically significant improvement over placebo.

Based on the absence of statistical significance and as previously agreed with FDA, Omeros will not submit an application for approval of narsoplimab in this indication and will discontinue the ARTEMIS-IGAN clinical trial.

Shares of Omeros fell nearly 40 percent to $1.39 in early trading following the news.

The primary endpoint in the study is reduction in proteinuria assessed by 24-hour urine protein excretion (UPE) at 36 weeks compared to placebo in the intent-to-treat population of nephropathy patients with high baseline proteinuria.

Omeros said the UPE reduction in the placebo group was markedly greater than that reported in trials of other agents in IgA nephropathy.

IgA nephropathy is the most common form of primary glomerulonephritis globally and is responsible for 10 percent of all dialysis patients worldwide. Up to 50 percent of IgA nephropathy patients develop end-stage renal disease and require dialysis within 20 years of diagnosis. Given the deleterious effects of steroids, there remains an unmet need for an alternative treatment option for IgA nephropathy.

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.

“We will conduct more detailed analyses of the data to understand better the outsized placebo effect and the overall trial results and to try to identify useful biomarkers,” said Gregory Demopulos, chairman and CEO of Omeros. The funds earmarked for commercialization in IgAN and continuation of the ARTEMIS-IGAN trial will be redirected to our other later-stage programs, including our ongoing phase 2 and upcoming phase 3 programs for our alternative pathway inhibitor OMS906.”

Demopulos said the company will also continue to focus on its near-term goal to resubmitting its application to the FDA seeking approval for narsoplimab in hematopoietic stem-cell transplant-associated thrombotic microangiopathy. In 2021, the FDA told the company it would not consider approval until it addressed deficiencies in the application.

Photo: Gregory Demopulos, chairman and CEO of Omeros

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