Rapt Therapeutics had been holding out hopes that its immunology drug zelnecirnon still had a future despite facing a clinical hold, but the latest feedback from the FDA has persuaded the biotech to give up on the program.
Trials of the CCR4 antagonist were placed on hold by the agency back in February after a patient in a phase 2b atopic dermatitis study suffered liver failure and required a transplant. While the cause was unknown, Rapt said at the time that it could potentially have been related to the drug. By May, the company confirmed it was winding down both the AD trial and a mid-stage study in asthma.
Despite these setbacks, CEO Brian Wong, M.D., Ph.D., said in May that the company still expected to have enough data to chart the drug’s path forward, even if they weren’t statistically significant.
Rapt pointed out again today that no cases of liver toxicity or any other treatment-related serious adverse event were reported in any participants from the phase 2b study of zelnecirnon. But the company also confirmed it has now moved to terminate the zelnecirnon program following fresh feedback from the FDA.
“In light of the agency’s feedback, we do not see a viable path forward for zelnecirnon, although we continue to believe that CCR4 remains an exciting target with the potential to provide a safe, oral therapeutic option across a number of inflammatory diseases,” Wong said in this morning’s release.
Rapt’s stock had been riding high around the $25 mark in the opening weeks of the year before the clinical hold brought it crashing down. This morning’s announcement did further damage, wiping 50% of the share price in pre-market trading to bring it down to $1.48 per share from a Friday closing price of $2.89.
Removing zelnecirnon means the biotech’s sole remaining clinical-stage asset is tivumecirnon, a phase 2 oncology med being tested alone and in combination with Merck & Co.'s megablockbuster cancer therapy Keytruda.
“We plan to continue advancing our next-generation CCR4 compounds with improved safety margins for inflammatory disease and expect to identify a new candidate in the first half of 2025,” Wong said. “Additionally, we continue to actively pursue in-licensing opportunities for clinical-stage assets.”