Clovis Oncology reported disappointing results from its LEAP (Low hENT1 and Adenocarcinoma of the Pancreas) study of CO-101 versus gemcitabine in metastatic pancreatic cancer. There was no difference in overall survival between the two arms in either the primary analysis of the hENT1-low patient population, or in the overall intent-to-treat population. Median survival in each arm was approximately six. Toxicities were comparable between the two arms, and no differences were observed in any subgroup analyses. Key prognostic variables, including performance status and age, were balanced between the hENT1-low and -high groups.
The study also demonstrated that, contrary to the results of numerous published retrospective studies, hENT1 status had no impact on survival for patients on gemcitabine.
CO-101 is a lipid-conjugated form of gemcitabine. It was designed to enter cancer cells regardless of hENT1 expression. CO-101 was targeted at patients with pancreatic cancer whose tumors express low amounts of hENT1 and, therefore, were expected to be resistant to standard gemcitabine therapy.
As part of the LEAP study, Clovis established a collaboration with Ventana Medical Systems to develop an in vitro diagnostic to measure tissue hENT1 expression and enable prospective classification of patients as either hENT1-high or hENT1-low. Clovis utilized this IVD to establish the definition of hENT1-high and hENT1-low patients from a number of clinical studies of gemcitabine, which allowed outcome data to guide an optimized definition of “hENT1-low” that identified patients who were expected to derive little benefit from gemcitabine therapy.
“We are obviously disappointed with these results, which are unambiguous,” said Patrick J. Mahaffy, president and CEO of Clovis Oncology. As a consequence of these results, Clovis will suspend all development of CO-101, pending further evaluation of the LEAP data.