Antibiotics May Interfere with Nivolumab Efficacy in Patients with Head and Neck Squamous Cell Carcinoma.

INTRODUCTION: Patients with the head and neck squamous cell carcinoma (SCC) are often treated with immune checkpoint inhibitors (ICIs). Recently, antibiotic intake was reported to lower the efficacy of ICIs in patients with several types of cancers. However, it is unclear if antibiotics affect the efficacy of ICIs in patients with head and neck SCC. We retrospectively assessed the influence of antibiotics on the treatment efficacy of nivolumab, an ICI, in patients with head and neck SCC. METHODS: We reviewed the medical records of patients with head and neck SCC treated with nivolumab at the Department of Medical Oncology, Tohoku University Hospital, between 2017 and 2021. Patients who received oral or intravenous antibiotics from a month before the day of nivolumab initiation to the day of the first imaging evaluation of ICI efficacy were assigned to the antibiotic-treated group. The remaining patients were assigned to the antibiotic-untreated group. The response rate (RR), progression-free survival (PFS), and overall survival time (OS) of both groups were compared. RESULTS: Forty-five patients were assigned to the antibiotic-treated group and 19 to the antibiotic-untreated group. The RR, median PFS, and median OS of the antibiotic-treated group were 23.7%, 3.2 months (95% confidential interval [CI]: 2.0-4.1), and 8.4 months (95% CI: 5.3-15.1) and those of the antibiotic-untreated group were 42.1%, 5.8 months (95% CI: 2.3-16.7), and 18.4 months (95% CI: 6.2-23.1), respectively. The PFS of the antibiotic-untreated group was significantly longer than that of the antibiotic-treated group. CONCLUSION: Our findings indicate that antibiotic treatment significantly shortens the PFS with nivolumab therapy in patients with head and neck SCC.

Antibiotic Treatment Improves the Efficacy of Oxaliplatin-Based Therapy as First-Line Chemotherapy for Patients with Advanced Gastric Cancer: A Retrospective Study.

Purpose: One of the first-line treatment for gastric cancer patients is oxaliplatin, and the efficacy of this chemotherapeutic can be attenuated by the microbiome. In this study, we retrospectively evaluated whether treatment with antibiotics improved the efficacy of oxaliplatin-based chemotherapy in patients with advanced gastric cancer. Patients and Methods: Fifty-four patients were assigned to the antibiotic-treated group and 35 to the antibiotic-untreated group. Results: The response rate of oxaliplatin-based chemotherapy in the antibiotic-treated and antibiotic-untreated groups was 66.7% and 41.4%, respectively (p = 0.038). The median progression-free survival after oxaliplatin-based chemotherapy in the antibiotic-treated and antibiotic-untreated groups was 8.8 and 5.2 months, respectively (hazard ratio = 0.456, 95% confidence interval = 0.254-0.819; p = 0.007, Log rank test). Univariate and multivariate analyses revealed that antibiotic treatment was the only clinical parameter that correlated with the response to oxaliplatin. Conclusion: Antibiotic treatment could be used therapeutically to enhance the efficacy of oxaliplatin-based chemotherapy in patients with advanced gastric cancer.