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.