XBiotech sinks on Phase III colorectal data

XBiotech Inc. (NASDAQ:XBIT) fell $8.10 (33%) to $16.80 on Tuesday after reporting results from a Phase III trial of its Xilonix human mAb against IL-1 alpha to treat advanced colorectal cancer. On the primary endpoint of clinical response rate, which assessed lean body mass and patient-reported fatigue, pain and appetite, the company said 33% of Xilonix-treated patients responded versus 19% for placebo (p=0.0045). XBiotech said those results were for "patients with advanced disease and multiple symptoms known to inversely correlate with overall survival," but did not respond to inquiries whether such patients were the entirety of those enrolled in the 309-patient study.

The company also said it did not compare overall survival between treatment arms because all patients were eligible to receive Xilonix after eight weeks. Instead, XBiotech pooled responders from treatment and placebo arms and compared OS versus non-responders from both arms. On that measure, OS was 11.5 months among responders compared with 4.2 months in non-responders. ...