Phase III data shows improved response rate of Xilonix (monoclonal antibody) in colorectal cancer- XBiotech

XBiotech has presented positive results from a pivotal Phase III trial of Xilonix, monoclonal (IgG1k) antibody immunotherapy for the treatment of advanced colorectal cancer (CRC). In the study, Xilonix-treated patients with advanced disease and multiple symptoms known to inversely correlate with overall survival experienced a 76% relative increase in clinical response rate (CRR), a novel measure of anti-cancer activity, after 8 weeks of therapy compared to placebo (33% vs. 19%, respectively).

In addition, clinical response correlated with improved overall survival. Among responders (in both treatment and placebo arms), clinical response was associated with a 2.7-fold increase in overall survival (11.5 versus 4.2 months in responders vs. non-responders, respectively). Overall survival was not compared between treatment arms because after 8 weeks, all patients were eligible to receive study drug. Treatment with Xilonix was well tolerated, with an adverse event profile comparable to placebo. In addition to increased overall survival, responders gained more lean body mass compared to non-responders, had reduced fatigue and pain and improved appetite. Control of thrombocytosis and systemic inflammation (IL-6), which are known prognosticators of overall survival, were also significantly improved in responders vs. non-responders.

There was a notable lack of toxicity associated with Xilonix treatment in the study. The most common adverse events (AEs) reported were abdominal pain, peripheral edema, fatigue, anemia, constipation, decrease in weight, asthenia, decreased appetite and nausea. The data were presented at the 18th European Society of Medical Oncology (ESMO) World Congress on Gastrointestinal Cancer.