Impact of intestinal dysbiosis-related drugs on the efficacy of immune checkpoint inhibitors in clinical practice

[Purpose]: Intestinal dysbiosis has emerged as a biomarker of response to immune checkpoint inhibitors (ICIs). It can be caused by antibiotics, although it may also result from the use of other drugs that have been studied to a lesser extent. The objective of our study was to analyze the association between the use of potentially dysbiosis-related drugs and survival in patients treated with ICIs in the clinical practice.[Materials and methods]: A retrospective, multicenter, cohort study was conducted. Clinicopathological variables were collected and the concomitant use of drugs was analyzed. A descriptive analysis of variables and overall survival, estimated by the Kaplan–Meier method, was performed, and association with various independent variables was assessed using Cox regression.[Results]: We included 253 patients, mainly with non-small cell lung cancer and melanoma. The most commonly used drugs were acid reducers, prescribed to 55.3% of patients, followed by corticosteroids (37.9%), anxiolytic drugs (35.6%), and antibiotics (20.5%). The use of acid reducers (9 vs. 18 months, P < .0001), antibiotics (7 vs. 15 months, P < .017), anxiolytic drugs (8 vs. 16 months, P < .015), and corticosteroids (6 vs. 19 months, P < .00001) was associated with poorer overall survival. Furthermore, the greater the number of drugs used concomitantly with ICIs, the higher the risk of death (1 drug: hazard ratio, 1.88; CI 95%, 1.07–3.30; 4 drugs: hazard ratio, 4.19; CI9 5%, 1.77–9.92; P < .001).[Conclusion]: Response to ICIs may be influenced by the use of drugs that lead to intestinal dysbiosis. Although a confirmatory prospective controlled study is required, our findings should be taken into account when analyzing ICI efficacy