A Phase II Feasibility Study Combining Pembrolizumab and Metformin in Patients with Metastatic Head and Neck Cancer
Abstract
Purpose: Survival for recurrent/metastatic head and neck squamous cell carcinoma (R/M HNSCC) remains low with <20% immunotherapy response. Metformin increases tumor-infiltrating CD8+ T and natural killer (NK) cells, which harbor PD-1. In this phase II clinical trial (NCT04414540), we combined metformin and pembrolizumab to evaluate the overall response rate (ORR) in R/M HNSCC and assess NK-cell activity.
Patients and methods: Eligible patients were randomized 1:1 into two arms: (i) metformin extended-release (ER) dose escalation to 2,000 mg over 14 days followed by combination with pembrolizumab 200 mg every 3 weeks or (ii) pembrolizumab 200 mg every 3 weeks followed by combination with metformin ER 2,000 mg daily. The primary endpoint was ORR per RECIST 1.1. Nineteen evaluable patients were planned to estimate the proportion of approximately 32% ORR. Safety was evaluated according to Common Terminology Criteria for Adverse Events v5.0. The distribution, activation, and cytotoxic function of NK cells were analyzed via flow cytometry.
Results: Twenty-one patients were enrolled; 76% were male, 52% were smokers, and the median age was 64 years. Ten patients had oropharyngeal tumors, of which nine were p16+. Eighteen patients were evaluable for response, including four complete and five partial responses for an ORR of 50% [95% confidence interval (29-71)]. Combination therapy was well tolerated with no unexpected adverse events (AE). Five grade 3 AEs occurred: nausea, diarrhea,…
How strong is the evidence?
Evidence Hub reads this as a randomized trial, done in people. Its evidence level is 2 of 5 (High · randomized trial). Randomized trials of a reasonable size are the strongest single-study design.
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