Abstract A28: Concomitant use of antibiotics and immune checkpoint inhibitors in patients with solid neoplasms: Retrospective data from real-world settings

Abstract

Abstract Background: The use of antibiotics is known to alter the gut microbiome and it is hypothesized that use of antibiotics may also alter the response to checkpoint inhibitors (CPI). As data are limited from real-world settings, we performed a retrospective audit of patients who received CPI along with concomitant antibiotics. Patients and Methods: This study is a retrospective audit of prospectively collected database of patients who received CPI for advanced solid tumors in any line between August 2015 and November 2018 at Tata Memorial Hospital, Mumbai, India. Antibiotic use was recorded from two weeks before the start of CPI and concomitantly with CPI. All statistical calculations were performed using SPSS statistical software for Windows version 20.0. Results: A total of 155 patients were identified to have received CPI during the study period, of which 70 (44%) patients received antibiotics. Median PFS in patients who received antibiotics was 1.7 months (95% CI: 1.1-2.3) against 3.6 months (95% CI: 2.3-4.8) for patients who did not receive antibiotics (p=0.912). Median OS in the patients who received antibiotics was 3.9 months (95% CI: 1.8-11.4) as compared to 9.2 months (95% CI: 4.2-12.3) for patients who did not receive antibiotics with a trend to significance with p=0.053 (HR-1.023; 95%CI: 1.00-1.04). Among the patients who received antibiotics, median OS for patients who received ≤10 days of antibiotics was 8.8 months (95% CI: 4.2-11.2) while for patients receiving >10 days of antibiotics, it was 2.8 months (95% CI: 1.2-4.4), p=0.025 (HR 2.0, 95% CI: 1.1-3.7). Conclusions: This study shows that judicious use of antibiotics is required in patients on CPI or scheduled to be started on CPI. Note: This abstract was not presented at the conference. Citation Format: Akhil Kapoor, Vanita Noronha, Vijay M. Patil, Amit Joshi, Nandini Menon, Amit Janu, Kumar Prabhash. Concomitant use of antibiotics and immune checkpoint inhibitors in patients with solid neoplasms: Retrospective data from real-world settings [abstract]. In: Proceedings of the AACR Special Conference on the Microbiome, Viruses, and Cancer; 2020 Feb 21-24; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2020;80(8 Suppl):Abstract nr A28.