XBiotech's Colorectal Cancer Drug Claims Fall Apart, Shares Plummet

XBiotech’s Colorectal Cancer Drug Claims Fall Apart, Shares Plummet July 5, 2016
By Alex Keown, BioSpace.com Breaking News Staff

AUSTIN, Texas – XBiotech said its experimental colorectal cancer drug Xilonix demonstrated an increase in overall survivability among patients, however those figures appear to fall apart under close scrutiny, which is driving the company’s shares down more than 46 percent this morning.

On Sunday, Texas-based XBiotech said Xilonix produced a 2.7-fold increase in overall survival in patients, or about 11.5 months. However, in the same breath the company noted the same response was also seen in the placebo arms of patients as well. This was enough to send The Street’s Adam Feuerstein into a tizzy. Feuerstein called XBiotech’s claims “clinically meaningless sleight of hand.”

He said the company’s claims show it does not care if colon cancer patients in the late-stage clinical trial were treated with the company’s drug or a placebo.

Shares of XBiotech had fallen to $13.34 as of 11 a.m. The shares closed Friday at $24.90 per share. XBiotech calls Xilonix the first monoclonal antibody to “specifically target and neutralize interleukin-1 alpha (IL-1a), one of the most potent inflammatory signaling molecules.” The IL-1 pathway is believed to be a desirable target for anti-cancer therapy due to its potential role in both local and systemic effects of cancer.

Another claim by the company that enraged Feuerstein was XBiotech’s statement that “overall survival was not compared between treatment arms because after 8 weeks, all patients were eligible to receive study drug."

“In other words, XBiotech claims a credible survival analysis—Xilonix vs. placebo—was impossible to assess because patients randomized to placebo at the start of the trial crossed over to Xilonix after eight weeks,” Feuerstein said.

In a statement released by the company, Tamas Hickish, chairman of the Xilonix European Phase III Study and Consultant Medical Oncologist at Dorset Cancer Centre, said the late-stage study of Xilonix “has the potential to meet the real and urgent need for more effective, less toxic therapies for patients with advanced colorectal cancer.”

“In addition, this study provides evidence that novel endpoints based on symptom recovery can serve as a predictor of overall survival benefit and thus may be used to evaluate an anti-tumor agent in this disease,” Hickish said in a statement. One missing element to the study, Feuerstein noted, was a lack of mention if Xilonix was able to shrink tumors or delay tumor growth.

The lack of clear data in the late-stage study could jeopardize the company’s possible approval of Xilonix later this year by the European Medicines Agency. With a market cap of about $800 million, Feuerstein said the company could not afford any missteps with the drug.

“XBiotech expects European regulators to approve Xilonix for colon cancer patients in the fourth quarter, based on the phase III study results submitted earlier this year. But if the messy, confused clinical data disclosed Saturday are any indication, a Xilonix approval in Europe is far from a sure thing,” Feuerstein said.

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