Abstract

Introduction Anti-EGFR agents are standard treatments for patients with EGFR-mutant advanced NSCLC. The feasibility of combining erlotinib or gefitinib with the anti–programmed death 1 immunotherapy pembrolizumab was evaluated in the phase 1/2 KEYNOTE-021 study (NCT02039674).

Methods Adults with previously untreated stage IIIB/IV EGFR-mutant NSCLC were treated with pembrolizumab 2 mg/kg intravenously every 3 weeks plus oral erlotinib 150 mg daily in cohort E or oral gefitinib 250 mg daily in cohort F, using a 3 + 3 design with cohort expansion. rTumor response was evaluated per Response Evaluation Criteria in Solid Tumors version 1.1 by blinded independent central review. The primary objective was determination of a recommended phase 2 dose.

Results Twelve patients enrolled to receive pembrolizumab plus erlotinib and seven to receive pembrolizumab plus gefitinib. No dose-limiting toxicities or grade 5 events occurred. Pembrolizumab plus erlotinib was feasible, with adverse events similar to those expected for monotherapy. However, pembrolizumab plus gefitinib was not feasible due to grade 3/4 liver toxicity in five of seven patients (71.4%), leading to permanent treatment discontinuation in four patients. The most frequently occurring treatment-related adverse events with pembrolizumab plus erlotinib were rash (50.0%), dermatitis acneiform, diarrhea, hypothyroidism, and pruritus (33.3% each). The objective response rate was 41.7%, including response in all four patients with programmed death ligand 1 expression 50% or greater.