Impact of antibiotics and proton pump inhibitors on clinical outcomes of immune check point blockers in advanced non-small cell lung cancers and metastatic renal cell cancer.

Abstract

e20520 Background: Studies have suggested that antibiotics can negatively influence efficacy of immune check-point blockers (ICB) but the results are inconsistent. The impact of concomitant proton pump inhibitors (PPI) is not known. We evaluated whether antibiotic and PPI use in patients with advanced non-small-cell lung cancer (NSCLC) and metastatic renal cell cancer (RCC) affects ICB efficacy. Methods: We identified advanced NSCLC and RCC patients treated with anti-PD1/PD-L1 at our institution between 5/2015 to 1/2019. Data regarding systemic antibiotics and PPI use < 1 month or during ICB treatment were collected. The primary outcome was progression free survival (PFS) per response evaluation criteria in solid tumors (RECIST 1.1). Secondary outcomes were overall survival (OS) and objective response rate (ORR). Logistic regression and cox proportional hazards model were used for statistical analysis. Results: 87/148 (58%) and 40/55 (72%) patients received antibiotics and 57/148 (39%) and 17/55 (31%) received PPI < 1 month or during ICI therapy in NSCLC and RCC respectively. In RCC, antibiotic use was associated with inferior PFS (2.9 v 5.0 months, HR = 2.3 95%CI 1.0-5.0; p = 0.04) but OS and ORR were not affected. In NSCLC, antibiotic exposure was associated with superior PFS (5.0 v 2.5 months, HR = 0.5, 95% CI 0.3-0.7; p < 0.01), OS (13.0 v 8.0 months, HR = 0.5, 95% CI 0.3-0.8; p < 0.01) and ORR (33% v 11%, OR = 4.6, p < 0.01). On univariate analysis, there was trend towards inferior OS in NSCLC (9.0 v 13.0 months, p = 0.05) with PPI use. PPI use was not associated with other primary or secondary outcomes in both the cohorts. The antibiotic effect remained significant for PFS in NSCLC and RCC in multivariate analysis. Conclusions: Antibiotic use significantly affected PFS in both NSCLC and RCC. PPI use did not affect outcomes. In contrast to previous studies, this is the first study to show that antibiotic use was associated with favorable outcomes in NSCLC. More studies are needed to explain this association. Future clinical trials with ICB should consider stratification of patients based on antibiotic exposure.