First-line Everolimus and Cisplatin in Patients with Advanced Extrapulmonary Neuroendocrine Carcinoma: a Nationwide Phase 2 Single-Arm Clinical Trial

Background: Extrapulmonary neuroendocrine carcinoma (EP-NEC) are an aggressive subgroup of neuroendocrine neoplasms (NEN). Advanced EP-NEC is generally treated with platinum-based cytotoxic regimens, but progressive disease occurs rapidly, resulting in a poor prognosis. Genetic alterations in the mammalian target for rapamycin (mTOR) pathway have been identified in NEN, providing a rationale for treatment with the mTOR-inhibitor everolimus. Methods: A prospective phase 2 single-arm study included patients with advanced EP-NEC from three Dutch NEN expertise centres between March 2016 and January 2020. Treatment consisted of cisplatin 75 mg/m 2 every 3 weeks in combination with daily everolimus 7.5 mg for a maximum of six cycles, followed by maintenance everolimus until disease progression. Primary endpoint was disease control rate (DCR), defined as the sum of overall response rate (ORR) plus the rate of stable disease according to RECIST 1.1, assessed at 9-week intervals. Toxicity was evaluated according to CTCAE version 5.0. Results: Thirty-nine patients, with a median age of 64 years (range: 28–74), of whom 20 (51%) were male, were enrolled. DCR was 82.1% (95% confidence interval (CI): 66.4–92.4), with an ORR of 58.9% (CI: 42.1–74.4). Median duration of response was 6.4 (CI: 5.8–7.0) months and median progression-free survival was 6.0 (CI: 4.3–7.8) months. Three patients (8%) had durable responses lasting > 12 months. Median overall survival was 8.7 (CI: 7.8–9.6) months. Most common grade 3/4 toxicities were haematological (36%) and renal (21%). Conclusion: Everolimus in combination with cisplatin is an effective first-line treatment option for advanced EP-NEC, especially in highly selected patients. Trial registration: Clinicaltrials.gov, NCT02695459, https://clinicaltrials.gov/ct2/show/NCT02695459 .