The European Medicines Agency’s Human Medicines Committee (CHMP) on Friday issued a negative opinion for Omeros Corp.’s (NASDAQ:OMER) narsoplimab.
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The company was seeking approval for Yartemlea (narsoplimab) for adults and children from two years of age with hematopoietic stem cell transplant-associated thrombotic microangiopathy (TA-TMA).
Thrombotic microangiopathy is a serious and potentially life-threatening complication following HSCT, a procedure in which the patient’s bone marrow is replaced by stem cells from a donor to form new bone marrow that produces healthy cells.
EMA Cites Study Design Concerns And Limited Pediatric Data
The EMA panel said the company failed to provide sufficient evidence to demonstrate Yartemlea’s effectiveness.
The pivotal study did not include a placebo or active comparator arm, and patients received other medications alongside Yartemlea, making it difficult to determine whether any observed benefits were attributable to Yartemlea.
Regulators also raised concerns over the study design, limiting the interpretability of the results.
Published studies showed that other treatments for thrombotic microangiopathy produced similar outcomes, while comparisons of survival data from Yartemlea-treated patients with external untreated patients were considered unreliable for confirming the drug’s benefit.
For pediatric use, regulators said available data were insufficient to support the proposed dose or adequately assess safety and efficacy.
Omeros intends to request re-examination of the CHMP opinion.
US Approval and Reimbursement Progress Continue
In December 2025, the U.S. Food and Drug Administration (FDA) approved Yartemlea for the same indication.
In January 2026, the company launched the drug in the U.S. market. During the quarter, gross product sales were $11.1 million, and associated net sales were $9.9 million.
In April, the U.S. Centers for Medicare & Medicaid Services (CMS) assigned a permanent Healthcare Common Procedure Coding System J-code specific to Yartemlea. The J-code becomes effective on July 1, 2026.
The update simplifies billing and reimbursement across payors.
Also in April, CMS, in its Inpatient Prospective Payment System proposed rule, recommended approval of the New Technology Add-On Payment (NTAP) for Yartemlea.
NTAP provides additional payments to hospitals for certain high-cost, innovative technologies, helping bridge the gap until standard payment systems incorporate them.
The final rule is expected in August, with NTAP expected to be effective Oct. 1, 2026.
OMER Stock Price Activity: Omeros shares were down 18.56% at $8.73 at the time of publication on Friday, according to Benzinga Pro data.
Image via Shutterstock/ Anusorn Nakdee
