Autoimmune drug flops late-stage trial

Sept. 10, 2021

A drug that Sanofi picked up in its $3.68 billion buyout of Principa Biopharma has failed to hit its primary endpoint in a phase 3 trial. 

The drug, rilzabrutinib, was being tested on patients with pemphigus, a rare but debilitating autoimmune disease that causes painful blisters on the skin. In the trial, the companies had hoped to show that the drug led to complete remission at 29 to 37 weeks, but ultimately, rilzabrutinib did not fare better than a placebo.

Although the trial failure cast a cloud of skepticism over Sanofi’s major deal with Principa, the companies said that there are still a number of potential indications for rilzabrutinib. Because the drug inhibits the BTK enzyme, which is involved in a variety of immune-related processes, the drug is soon entering phase 2 trials for a number of autoimmune diseases including asthma, atopic dermatitis, and more.