FDA Clinical Hold on RAPT Therapeutics

Shares of RAPT Therapeutics took a major hit, dropping over 65% in premarket trading following a serious adverse event that led the U.S. Food and Drug Administration to halt two studies conducted by the biopharmaceutical company.

The Situation

• The clinical hold affects a Phase 2b study of zelnecirnon in atopic dermatitis, where one patient experienced liver failure.
• Additionally, a Phase 2a study of zelnecirnon in asthma has also been put on hold.
• While the cause of the adverse event is not yet determined, it is possibly linked to zelnecirnon.

Serious Adverse Event

• Specific details regarding the serious adverse event have not been released.
• As per the FDA, serious adverse events can lead to disability, be life-threatening, result in hospitalization or death, or cause birth defects.

Response and Investigation

• RAPT was informed about the hold verbally by the FDA and is awaiting an official clinical-hold letter.
• The company is conducting a thorough investigation into the incident.
• The patient involved had a complicated medical history, including the use of an herbal supplement associated with liver failure and a documented Covid-19 infection during that time.

Market Impact

• With shares closing at $25.97 on Friday, they dropped to $9 in premarket trading post the news.

RAPT Therapeutics seeks to navigate this challenging period as they work diligently to address the situation under FDA scrutiny.