NP-101 in combination with nivolumab and ipilimumab in metastatic extrapulmonary neuroendocrine carcinomas (EP-NECs): A pilot study

Extrapulmonary neuroendocrine carcinomas (EP-NECs) are a heterogeneous group of rare tumors with poor clinical outcomes. These patients have limited treatment options after progressing on first-line platinum-based chemotherapy. Although dual immune checkpoint inhibitors (ICIs) with anti-CTLA-4 and anti-PD-1 blockade have significantly improved outcomes for several solid tumors, they demonstrated modest activity for EP-NECs with 9-26% response rates and low survival rates. Preliminary data demonstrated that NP-101 (Nigella sativa formulation) enhances T-cell infiltration and is synergistic with dual ICPIs in NECs' cellular models. This pilot study evaluated the tolerability and efficacy of NP-101 plus nivolumab and ipilimumab in patients with metastatic EP-NECs refractory to first-line platinum-based chemotherapy. This is a single-arm pilot study (NCTNCT05262556) in which patients with metastatic EP-NECs received NP-101 (oral capsules), 3,000 mg daily, plus ICPIs (intravenous nivolumab 3 mg/kg and ipilimumab 1 mg/kg) every 3 weeks for four cycles. Nonprogressors received NP-101 (3,000 mg daily), plus biweekly maintenance of nivolumab (240 mg), and then completed 24 weeks of treatment. Treatment-related adverse events (TR-AEs) were characterized according to CTCAE v4.03. The response rate was estimated according to Response Evaluation Criteria in Solid Tumors (RECIST), version 1.1. The Kaplan-Meir method was used to estimate median PFS and OS. Twelve patients received ≥1 dose of NP-101 and nivolumab plus ipilimumab. There were no dose-limiting toxicities (DLTs). Grade 1/2 TR-AEs occurred in 100% (12/12) of patients. The most common G1/2 TR-AEs included the following: fatigue (75%), nausea (41.7%), pruritus (41.7%), muscle weakness (33.3%), vomiting (25%), rash (25%), and abdominal pain (25%). Eight patients (66%) experienced grade 3/4 TR-AEs, including rash (33.3%), nausea (16.7%), vomiting (16.7%), and transaminitis (16.7%). No treatment-related grade 5 toxicities or deaths were recorded. The objective response rate was 41.7% (2/12 (16%) complete response (CR) + 3/12 (25%) partial response (PR); 95% CI: 15.2-72.3%) for all patients and 50% (2/8 CR + 2/8 PR, 95% CI: 0.16-0.84) for patients with NEC of gastrointestinal origin. The median duration of response was 7.5 months. As for the median progression-free survival, it was 5.7 months, and the median overall survival (OS) was 10.5 months with a median follow-up of 10.4 months. The combination of NP-101 plus dual ICPIs (nivolumab and ipilimumab) was safe and well tolerated with preliminary evidence of antineoplastic activity. Currently, a randomized phase II clinical trial evaluating the combination is under development.