European Medicines Agency issued a negative opinion on Omeros’ Yartemlea, citing insufficient data, lack of comparator, study design flaws and unclear pediatric dosing for its TA-TMA indication. OMER stock slid 18%, on track for a seven-month low, after the regulator granted 15 days to request a re-examination.
The EMA’s Committee for Medicinal Products for Human Use refused marketing approval for Yartemlea (narsoplimab) in hematopoietic stem cell transplant-associated thrombotic microangiopathy, citing insufficient evidence of efficacy, absence of a placebo or active comparator and unclear pediatric dosing data.
Regulators flagged mid-study protocol changes, questioned the measurement of therapeutic benefit given patients’ concurrent medications, and noted that the main trial did not isolate Yartemlea’s effect from other treatments, undermining the reliability of efficacy claims.
Shares of Omeros dropped 18% on the news, heading toward their lowest level since November, as investors reassessed the commercial prospects of Yartemlea in the European market and the potential revenue impact of a delayed or denied approval.
Omeros has 15 days to request a re-examination of the EMA’s opinion or submit additional data; Yartemlea remains approved by the FDA for the same indication in adults and children as young as two years old.
