Initial Therapeutic Approach with Pembrolizumab in Synchronous Multiple Cancers, Including Non-Small Cell Lung Cancer, Highly Positive for Programmed Death-Ligand 1 Expression

Abstract

Treatment of synchronous multiple primary cancers is clinically difficult. We report four cases of synchronous primary cancers, including advanced and metastatic non-small cell lung cancer (NSCLCs) highly positive for programmed death-ligand 1 (PD-L1) expression and initially treated with pembrolizumab. Pembrolizumab was efficacious in two patients with NSCLC lesions, followed by chemoradiotherapy for esophageal cancer (case 1) and chemotherapy for gastric cancer (case 2). Both cancers in case 1 showed a complete response for 3 years, while progression of the accompanying gastric cancer resulted in mortality at 20 months in case 2. Both NSCLC and gastric cancer in case 3 failed to respond to pembrolizumab, but the accompanying laryngeal cancer in case 4 showed a complete response, and cytotoxic chemotherapy for NSCLC was continued for 18.0 months. Our clinical experience suggests that pembrolizumab is a useful therapeutic approach for patients with synchronous cancers, including NSCLC that highly expresses PD-L1.