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The following is a summary of “Antibiotics use decreases survival in cutaneous squamous cell carcinoma patients receiving immune checkpoint inhibitors,” published in the January 2025 issue of Oncology by Bonnefin et al.

Immune checkpoint inhibitors are now the first-line treatment for patients with advanced cutaneous squamous cell carcinoma (cSCC). Although prior studies have shown that antibiotics may impair the efficacy of ICIs in various cancers, their influence on cSCC has not been extensively investigated. This single-center retrospective study aimed to evaluate the impact of ATB exposure at the onset of ICI treatment in patients with cSCC and its correlation with clinical outcomes. The study included 104 patients who initiated anti-PD-1 therapy between March 2019 and July 2023. ATB exposure was assessed within 3 months before and after ICI initiation (ATB 3-3), and within 1 month before and after (ATB 1-1). Patient outcomes, including DCR, progression-free survival, OS, and disease-specific survival, were compared between ATB-exposed and unexposed groups. 

ATB exposure was common, with 45% and 20% of patients classified into the ATB 3-3 and ATB 1-1 subgroups, respectively. DCR at 3 months was significantly lower in both ATB 3-3 and ATB 1-1 subgroups compared to their respective control groups (p=0.02 and p=0.03). Furthermore, patients in the ATB 1-1 subgroup had significantly shorter OS and DSS (p=0.04 and p=0.01, respectively). Median PFS was markedly reduced in the ATB 1-1 group, at 127 days, compared to the control group, where the median was not reached (p=0.005). These findings underscore the potential detrimental effect of ATB use on ICI efficacy in patients with cSCC, particularly when administered within 1 month before or after ICI initiation. Given the high frequency of ATB exposure in this population, these results highlight the need for judicious use of antibiotics and further research to optimize treatment strategies. This study provides valuable insights into the interaction between ATBs and ICIs, emphasizing the importance of minimizing factors that could compromise therapeutic outcomes in cSCC management.

Source: sciencedirect.com/science/article/abs/pii/S0959804925000048