Exploratory analysis of clinical trials in various tumor types have demonstrated potential improvements in overall response rate (ORR) to chemotherapy after exposure to vaccine-based immunotherapy. The objective of this retrospective study was to determine if single-agent chemotherapy (3rd-line or beyond) would yield improved ORR when given after exposure to programmed death-(ligand)1 inhibitors (anti-PD1) in metastatic non-small cell lung cancer (NSCLC).

We queried the Thoracic GEMINI database of MD Anderson Cancer Center for patients treated between 06/12 and 11/16 who received at least one single-agent chemotherapy as 3rd-line or beyond, following progression after platinum-based chemotherapy and anti-PD1. We evaluated efficacy outcomes to each therapy, including ORR by RECIST version 1.1, progression-free survival (PFS), and overall survival (OS).

Out of 306 anti-PD1-treated patients registered in the database, 28 met eligibility criteria - 54% were male, median age was 66 years, 82% had adenocarcinoma, and 71% were former/current smokers. The anti-PD1 and single-agent chemotherapy most commonly used were nivolumab (86%) and docetaxel (50%), respectively. ORR to single-agent chemotherapy after exposure to anti-PD1 was 39% (11/28 patients, 8 confirmed). In contrast, ORR to first-line chemotherapy in this cohort was 37%. Liver metastasis was the only factor associated with response to single-agent chemotherapy on univariate analysis (p<0.05).

In NSCLC patients, the confirmed ORR to single-agent chemotherapy after immunotherapy exposure was higher as compared to historical data from the pre-anti-PD1 era, and approached ORR to first-line platinum-based chemotherapy. Further investigation of a possible immunotherapy-induced chemosensitization effect is warranted.