Antibiotic Exposure Prior to First-Line Immune Checkpoint Blockade Negatively Impacted Survival Outcomes Among Patients With Melanoma

According to results from a retrospective cohort study, antibiotic exposure within 60 days prior to initiation of immune checkpoint blockade was associated with worse progression-free survival (PFS) and overall survival (OS) results among patients with treatment-naïve cutaneous or mucosal melanoma when compared with antibiotic exposure after initiation of immune checkpoint blockade. 

“The interaction of gut microbiome and immune system is being studied with increasing interest,” stated Eleftheria Chorti, West German Cancer Center, Essen/Düsseldorf, Germany, and coauthors. “Disturbing factors, such as antibiotics may impact the immune system via gut and interfere with tumor response to immune checkpoint blockade.” 

This multicenter study enrolled 578 patients with treatment-naïve, non-resectable advanced cutaneous or mucosal melanoma who had received either no antibiotics or antibiotics within 60 days before or after initiation of treatment with a first-line anti-PD-1 based immune checkpoint blockade. The primary end points were PFS and OS according to antibiotic exposure. Data was analyzed separately in the time periods before and after the start of antibiotics to account for immortal time bias.

At analysis, 7% of patients received antibiotics before initiation of immune checkpoint blockade while 19% received antibiotics after initiation of immune checkpoint blockade. According to multivariate analysis, antibiotic exposure prior to immune checkpoint blockade was associated with worse PFS (adjusted hazard ratio [HR], 1.75; 95% confidence interval [CI], 1.22 to 2.52) and OS (adjusted HR, 1.64; 95% CI, 1.04 to 2.58). The use of antibiotics after the start of immune checkpoint blockade had no effect on PFS (adjusted HR, 1.19; 95% CI, 0.89 to 1.60 or OS (adjusted HR, 1.08; 95% CI, 0.75 to 1.57).

Study results demonstrated “that [prior antibiotic treatment] has a negative impact on PFS in melanoma patients,” stated Dr Chorti et al. “The latter observation allows us to consider antibiotic use for suspected bacterial infections during [immune checkpoint blockade] as a safe decision in terms of PFS and OS.”

Source: 

Chorti E, Kowall B, Hassle JC, et al. Association of antibiotic treatment with survival outcomes in treatment-naïve melanoma patients receiving immune checkpoint blockade. Eur J Cancer. Published online: January 18, 2024. doi:10.1016/j.ejca.2024.113536