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Efficacy of Checkpoint Inhibitors in Neuroendocrine Neoplasms: Mayo Clinic Experience
Jennifer J Gile1, Alex J Liu2, Patrick W McGarrah1
1From the Division of Oncology, Department of Medicine, Mayo Clinic, Rochester, MN.
Objectives:
Checkpoint inhibitors (CPIs) for low- and intermediate-grade neuroendocrine tumors (NETs) have been associated with limited efficacy; recent studies suggest CPIs may represent promising treatment for high-grade neuroendocrine neoplasms (NENs).
Methods:
We examined 57 patients with NENs who were treated with CPIs to determine if NETs and neuroendocrine carcinomas (NECs) respond to immunotherapy.
Results:
Patients with poorly differentiated NECs on CPI monotherapy had an objective response rate (ORR) of 0% and median progression-free survival (PFS) of 2.1 months (95% confidence interval [CI], 0.5-4.6). Patients with poorly differentiated NECs on dual CPI therapy had an ORR of 13% and PFS of 3.5 months (95% CI, 1.4-not reached [NR]). Patients with poorly differentiated NECs on CPI and cytotoxic therapy had an ORR of 36% with PFS of 4.2 months (95% CI, 1.6-NR). Well-differentiated grade 1 and 2 NETs on CPI monotherapy had an ORR of 25% with PFS NR. Well-differentiated grade 3 NETs had 0% ORR with a PFS of 2.9 months (95% CI, 1.4-4.2) on CPI monotherapy.
Conclusions:
Checkpoint inhibitor therapy shows limited activity in patients with NENs. Future studies should identify biomarkers that can help identify patients who are likely responders to immunotherapy.
