Rapt Therapeutics (RAPT.O) announced on Tuesday that the U.S. FDA had placed two mid-stage trials of the company’s drug for treating eczema and asthma on hold, following the observation of liver failure in one of the patients.
Shares of the San Francisco-based company plummeted to a record low of $8.5 in early trading.
Rapt stated it was scrutinising the patient’s medical history and described the liver toxicity incident as an “isolated event”.
During a conference call, CEO Brian Wong disclosed that the patient had a drug allergy to Dupixent, a medication for the conditions manufactured by Regeneron (REGN.O) and Sanofi (SASY.PA), and had also undergone thyroid hormone replacement therapy for Hashimoto’s disease, an autoimmune condition.
The patient was reported to have contracted COVID-19 at the time of the event and was using ashwagandha, a herbal supplement associated with liver failure, according to the company.
Analyst Alex Thompson from Stifel remarked that the clinical hold “represents a major setback” for Rapt and could lead to “a meaningful delay in trial timelines”.
Rapt had enrolled approximately 350 patients across the two mid-stage trials and a preceding early-stage study of the drug, zelnecirnon, but no instances of liver toxicity were noted in any other patient.
In November, the company had indicated it anticipated reporting trial results for patients with atopic dermatitis (eczema) by mid-2024, while also progressing with enrollment for its asthma study.
Subsequent to the hold, Rapt will cease dosing existing patients and suspend enrollment of new participants while undertaking a thorough investigation into the case.