Immune checkpoint inhibitors in neuroendocrine tumors: A single institution experience with review of literature

This unique case series and review of literature suggests that immune checkpoint inhibitors may have clinical activity in neuroendocrine tumors. OBJECTIVE: Summarize advances of immuno-oncology in neuroendocrine tumors with the help of a case series. DESIGN: Case series and review of literature. INTERVENTION OR EXPOSURE: The patients were treated with immune checkpoint inhibitors (pembrolizumab or nivolumab). MAIN OUTCOME(S) AND MEASURES(S): Life expectancy, quality of life, disease progression. RESULTS: Maximum durable response of 16 months in one of the patients so far. All patients showed improvement in quality of life before disease progression. Two out of four are still on therapy. None of the patients experienced immune checkpoint inhibitor associated side-effects. All patients had failed standard of care therapy prior to the initiation of immune checkpoint inhibitors and were on the verge of hospice. CONCLUSIONS: Immune checkpoint inhibitors have revolutionized cancer management and the last 5 years have seen a rapid expansion in the indications for this class of drug. Neuroendocrine tumors, unfortunately, have been slow to catch on to the immuno-oncology, partly due to difficulties in establishing relevant preclinical neuroendocrine tumors models for immune-oncology studies. In this manuscript, we review the current status of immunotherapy in neuroendocrine tumors.