Effect of concomitant medications on overall survival in patients with cancer undergoing immunotherapy.
94 Background: The response to Immunotherapy (IO) is known to be affected by concomitant medications including corticosteroids and antibiotics. We evaluated the medication history of patients undergoing IO to explore other medications that affect overall survival and to estimate the relative impact of each medication when given in combination. Methods: A retrospective review of patients with advanced cancer who received IO from 2011 to 2017 at the Ohio State University was performed with IRB approval. Data were extracted from the medical record, including medication history 180 days around the start of IO therapy. Data were collected in a REDCap database. Overall Survival (OS) was calculated from the initiation of IO. Cox Proportional-Hazards models were used and evaluated by log-rank test at alpha = 0.05. All calculations were performed using the survival and survminer packages in R. Results: Patients who received antibiotics or corticosteroids had decreased OS (p = 0.019 and p = 0.043, respectively) across several cancer types. Medications that were not significantly associated with OS included statins (p = 0.38), proton pump inhibitors (p = 0.94), H2 blockers (p = 0.27) and NSAIDS (p = 0.46). A total of 159 patients had complete data for all medications suitable for modeling relative effects. 149 (94%) of patients received antibiotics within 180 days of IO and 19 (12%) received both corticosteroids and antibiotics. The combination of corticosteroids and antibiotics had lower median OS than antibiotics alone or neither medication (p < 0.0018). A Cox Proportional Hazards model of antibiotics and corticosteroids, controlling for age, BMI and ECOG performance status, showed antibiotics, age and BMI to be significant predictors. Conclusions: Antibiotics and corticosteroids near the start of IO reduced overall survival, and the combination reduced the median overall survival further. However, a combined model that controlled for age, BMI and ECOG showed antibiotics, age and BMI to have a significant effect on OS. Though preliminary, these results suggest that antibiotics and corticosteroids may be affecting OS in the context of IO through overlapping pathways.