Sanofi-Aventis and partner Regeneron Pharmaceuticals have decided not to submit data from a mid-stage study of their investigational cancer drug aflibercept.

The companies have taken this decision despite unveiling Phase II data showing that advanced ovarian cancer patients receiving aflibercept experienced a statistically significant improvement in the primary study endpoint. That was mean time to first repeat paracentesis, ie removal of fluid from the abdominal cavity) versus placebo.

George Yancopoulos, president of Regeneron Research Laboratories, noted that while the results demonstrate that aflibercept, a fusion protein targeting vascular endothelial growth factor is a clinically active agent, the data is not compelling enough. He said that “given the small number of patients enrolled in this study and the fragile health status of these advanced ovarian cancer patients, who had a median survival of only about three to four months, it is difficult to definitively assess the overall clinical benefit that might be derived from treatment in the real-world clinical practice setting”.

As a result, the companies will not submit these Phase II data for approval in symptomatic malignant ascites and Dr Yancopoulos said that “we will focus our efforts on completing the current Phase III programme which combines aflibercept with standard chemotherapy regimens”. The drug will now be investigated as a treatment of earlier-stage metastatic colorectal, non-small cell lung, pancreatic and prostate cancers, “which should begin delivering data in 2010”.