Researchers report the results of a new analysis from a phase III trial of patients with neuroendocrine tumors that begin in the gastrointestinal (GI) tract or have an unknown origin. Compared to placebo, everolimus was associated with a six- to eight-month longer time period before the cancer worsened. The study was presented at ASCO's 2016 Gastrointestinal Cancers Symposium in San Francisco.

"Everolimus has the potential to stop the cancer from growing for a prolonged period of time," said lead study author Simron Singh, M.D., MPH, FRCP(C), a medical oncologist at Sunnybrook's Odette Cancer Centre in Toronto, Canada.

The analysis included 175 patients with previously treated, advanced GI neuroendocrine tumors and 36 patients with neuroendocrine tumors of an unknown site of origin. All patients had non-functional tumors, meaning that the tumor caused few or no symptoms initially.

"In consultation with their oncologist, patients with neuroendocrine tumors may consider this as one of the new standard treatment options," said Dr. Singh.

Study patients were randomly assigned to receive everolimus plus best supportive care, or placebo plus best supportive care. All patients had tumors that progressed on other therapies, which included somatostatin analog (a standard hormone therapy for neuroendocrine tumors), surgery, or chemotherapy.

Overall, everolimus reduced the risk of disease progression by about 40% compared to placebo. Among patients with GI neuroendocrine tumors, the median progression-free survival was 13.1 months with everolimus vs. 5.4 months with placebo. In the group of patients with tumor of unknown origin, the median progression-free survival with everolimus and placebo was 13.6 and 7.5 months, respectively.

The most common adverse events in the everolimus arm were stomatitis, infections, diarrhea, peripheral edema, and fatigue.

"While everolimus is already approved to treat pancreatic neuroendocrine tumors, these results demonstrate that it may also be effective for a broader group of patients with neuroendocrine cancer," said Smitha Krishnamurthi, M.D., ASCO Spokesperson. "The findings may add a new treatment option for patients whose tumors have worsened despite other treatments."

While they are rare overall, the incidence of neuroendocrine tumors is on the rise.
"Currently there are limited treatment options for patients with GI neuroendocrine tumors, so this study is a welcome advancement in the field, opening the door to a new exciting treatment," say Dr. Singh. Everolimus has previously been approved for the treatment of pancreatic neuroendocrine cancer.

This study received funding from Novartis Pharmaceuticals.