FDA Halts RAPT Therapeutics Trials for Lead Drug

RAPT Therapeutics, a pharmaceutical company, has recently faced a setback as the FDA has imposed a clinical hold on two of its drug trials. The first trial, a Phase IIb study, was investigating the use of zelnecirnon for atopic dermatitis, while the second, a Phase IIa trial, was exploring its efficacy in treating asthma. This decision by the FDA followed an incident where a participant in the atopic dermatitis study experienced liver failure, the cause of which remains undetermined.

The company has reported a significant drop in its stock value, with a decline exceeding 67%. RAPT has clarified that approximately 350 patients were involved in the trials for zelnecirnon, and no other cases of liver toxicity were observed. The trials in question have halted dosing and enrollment, but the hold does not impact another ongoing trial for a different drug, tivumecirnon, which is being studied in oncology.

RAPT's CEO, Brian Wong, emphasized the company's commitment to patient safety and its intention to work closely with the FDA to resolve the issue. He stated that the company is awaiting a formal letter from the FDA that will provide more details and guide their investigation. Wong highlighted the patient's complex medical background, which included an autoimmune condition and a history of taking a supplement linked to liver issues, as well as an active COVID-19 infection at the time of the incident. The patient has since undergone a liver transplant and is reportedly recovering.

Prior to this clinical hold, RAPT was viewed favorably by analysts. Wolfe Research and Evercore ISI had both initiated coverage with an "outperform" rating, anticipating positive outcomes from the Phase IIb trial results. The Phase Ia/Ib results of zelnecirnon for atopic dermatitis had shown promising results, with the drug being well-tolerated and no serious adverse events reported.

The company continues to investigate the matter and is working diligently to lift the clinical hold imposed by the FDA. The outcome of this investigation and the FDA's feedback will be crucial in determining the future direction of the trials and the drug's development.