Xencor’s lead drug fails a PhII test for lupus, shares slide

Shares of Xencor tumbled Friday as the biotech tried to explain — largely unsuccessfully — why the failure of its Phase II lupus drug study was really an overall plus.

The mid-stage study of XmAb5871 enrolled 104 patients. But researchers said that the placebo effect was magnified after 10 patients dropped out of the control arm, compared to 2 in the drug arm. 

Bassil Dahiyat

Measuring the continued improvement in patients after 225 days, the company said that the drug arm hit 42% compared to a 28.2% response in the placebo arm. That qualified for a failed p value of 0.18 on the primary endpoint.

The drug did hit on a secondary for time to loss of improvement and safety and tolerability of XmAb5871. 

The study’s coordinating investigator, Joan Merrill, called the results “encouraging.”

That wasn’t what investors were looking for, though. The stock $XNCR dropped 15% on the failure.

Perhaps a partner would like to take the lupus drug from here?

“By year end, we plan to initiate a Phase III study of XmAb5871 in IgG4-RD, and we are exploring further development in SLE in the context of partnering,” noted CEO Bassil Dahiyat. “With six internal programs in autoimmune disease and cancer advancing in the clinic, we anticipate additional data readouts over the next two years.”

The best place to read Endpoints News? In your inbox.

Comprehensive daily news report for those who discover, develop, and market drugs. Join 47,500+ biopharma pros who read Endpoints News by email every day.

Free Subscription

Research Scientist - Immunology
Recursion Pharmaceuticals Salt Lake City, UT
Director of Operations
Atlas Venture Cambridge, MA

Visit Endpoints Careers ->