Rapt Therapeutics said it will close and unblind two mid-stage trials in atopic dermatitis and asthma after they were put on clinical hold earlier this year due to a case of liver failure.
The company is now working to clean the atopic dermatitis data and anticipates completing its analysis in the third quarter. It is also continuing to investigate the serious adverse event that triggered the clinical holds.
“Although there were a significant number of patients who were unable to complete the [atopic dermatitis] trial due to the hold, we believe we will have sufficient data, even if not statistically significant, to inform our path forward and support our discussions with the FDA,” CEO Brian Wong said in a release.
The biotech’s shares $RAPT dropped 32% on Thursday morning to around $5.40.
The two studies were evaluating the company’s lead candidate, a small molecule CCR4 antagonist named zelnecirnon. The atopic dermatitis program was in Phase 2b and the asthma program in Phase 2a.
In February, the FDA put both trials on hold after an atopic dermatitis patient experienced liver failure that was deemed “potentially related to zelnecirnon.” The patient had to undergo a liver transplant.
At the time, 229 patients were enrolled in the Phase 2b atopic dermatitis trial, and 110 had completed the 16-week dosing period, the company said Thursday. The Phase 2a asthma test — initiated in March 2023 — had aimed to recruit around 100 patients. The company didn’t share any additional information about the asthma trial.
“We think there remains a credible case that the [liver] event was idiosyncratic (underlying autoimmune disease and viral infection), though there are limited details for us to vet here,” Stifel analysts said Thursday.