An unscheduled interim analysis halted a fast-tracked phase III study of monoclonal antibody therapy Xilonix in advanced colorectal cancer patients with cachexia.
The primary endpoint of the study is overall survival, comparing survival in Xilonix treated patients to a control population provided only palliative therapy for cachexia.
Over half of the 40 patients enrolled in the trial have succumbed to disease. At the time of analysis, patients receiving Xilonix had a hazard ratio for risk of death of 0.33 (p=0.11) compared with controls. The strong hazard ratio reveals a marked trend for improved survival in the Xilonix treated group compared to controls, according to XBiotech, the drug’s sponsor.
The unscheduled analysis was enabled due to a halt in the study for protocol amendments, which XBiotech says are intended to correct what are believed to be barriers to patient enrollment. The company says is currently collaborating with the FDA on revisions that will ensure the protocol remains suitable for biological licensing applications.
The new protocol is said to permit recruitment of all advanced refractory colorectal cancer patients and will be randomized 2:1 against placebo. XBiotech is expecting patients to be enrolled under the revised protocol as early as October.
XBiotech used the interim overall survival data in a model to predict the statistical significance of the survival benefit over the projected complete course of the study.
Key pharmacodynamic measures were also reported to be consistent with the intended biological activity of the therapy; as well, secondary endpoints evaluating quality of life were consistent with the observed survival benefit in Xilonix patients.
