OBJECTIVES: Previous studies suggest worse outcomes for patients with cancer exposed to antibiotics who are treated with ICI. This study investigates the association between antibiotic exposure and survival among patients diagnosed with advanced melanoma or NSCLC receiving ICI therapy in an electronic health records (EHR)-claims linked dataset.

METHODS: Patients with advanced melanoma or advanced NSCLC diagnosed between 2013 and 2021 treated with ICI from the EHR-derived de-identified Flatiron Health Research Database linked with Komodo Health’s claims database were selected. The exposure group included patients with any antibiotic use from 42 days before to 28 days after ICI initiation. Antibiotic use was identified in claims through relevant NDC, ICD, or HCPCS codes. Patient characteristics, ICI treatment, and outcomes were identified through EHR. Cox proportional hazards models were used to compare real-world overall survival (rwOS) and real-world progression-free survival (rwPFS) across exposure groups.

RESULTS: A total of 3,271 patients were included, 521 (16%) with melanoma and 2,750 (84%) with NSCLC, of whom 1,350 (41%) had antibiotic exposure within the window of interest. Most common ICI treatments were pembrolizumab (59%) and nivolumab (26%). Median age at advanced diagnosis was 65 years (IQR: 59, 73); 53% were men (1,739); 65% were white (2,215), and 9.3% were Black (303). The unadjusted hazard of rwPFS for exposed patients was 1.13 (95%CI: 1.05 to 1.23, p<0.01), and 1.12 after adjustment (95%CI 1.03 to 1.22, p<0.01). Unadjusted and adjusted estimates of HR of rwOS were 1.31 (95%CI: 1.20 to 1.43, p<0.01) and 1.25 (95%CI: 1.14 to 1.37, p<0.01), respectively. Propensity score-weighted analysis revealed similar hazards of rwPFS and rwOS.

CONCLUSIONS: Antibiotic exposure around ICI initiation is associated with worse rwOS and rwPFS among patients with advanced melanoma or advanced NSCLC. Integrated claims and oncology EHR data enable investigation of associations between non-oncology drug exposure and oncology outcomes.