RAPT Therapeutics, Inc. (NASDAQ: RAPT) shares descended Tuesday. The clinical-stage, immunology-based biopharmaceutical company focused on discovering, developing and commercializing oral small molecule therapies for patients with significant unmet needs in inflammatory diseases and oncology, today announced that the U.S. Food and Drug Administration (FDA) has verbally notified the company that a clinical hold has been placed on the company’s Phase 2b trial of zelnecirnon (RPT193) in atopic dermatitis and its Phase 2a trial in asthma.
The company expects to receive a formal clinical hold letter from the FDA. The clinical hold determination was based on a serious adverse event of liver failure in one patient in the atopic dermatitis trial, the cause of which is currently unknown but which has been characterized as potentially related to zelnecirnon. Dosing of zelnecirnon has been halted in both clinical trials, as has enrollment of new trial participants. The clinical hold does not apply to RAPT’s ongoing trial of tivumecirnon (FLX475) in oncology.
A total of approximately 350 patients have been enrolled across three trials evaluating zelnecirnon - the two Phase 2 trials and an earlier Phase 1a/1b study. No evidence of liver toxicity has been observed with any other trial participant. Additionally, no evidence of liver toxicity was observed in nonclinical studies.
RAPT shares lost $16.78, or 64.8%, to $9.15.
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