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Do Antibiotics Impact the Efficacy of Pembrolizumab in Metastatic Urothelial Carcinoma?

By: Julia Fiederlein
Posted: Friday, October 8, 2021

According to Kazunari Tanabe, MD, PhD, of Tokyo Women’s Medical University, and colleagues, antibiotic use has been found to impact the efficacy of immune therapies. A retrospective analysis, which was published in the journal Urologic Oncology: Seminars and Original Investigations, revealed that the use of antibiotics seemed to be negatively associated with outcomes in patients with metastatic urothelial carcinoma who were administered the immune checkpoint inhibitor pembrolizumab.

“Antibiotics were associated with a decreased progression-free and overall survival,” the investigators commented. “[They] were also associated with disease progression.”

The investigators focused on 67 patients with chemotherapy-resistant metastatic urothelial carcinoma who were treated with pembrolizumab. They were classified into groups based on whether they were treated with (22%) or without (78%) antibiotics. The administered antibiotics included penicillin, cephalosporin, quinolone, and carbapenem.

The median durations of progression-free (1.1 vs. 8.9 months; P < .001) and overall (2.3 vs. 19.5 months; P < .001) survival seemed to be significantly shorter in those given antibiotics than in those who were not. Patients treated with antibiotics appeared to have significantly higher Eastern Cooperative Oncology Group performance status scores (P = .042). Based on multivariable analyses, antibiotic use seemed to be an independent predictor of progression-free (P < .001) and overall (P = .002) survival. No complete responses were observed in patients treated with antibiotics. The objective response rates with and without antibiotics were 13.3% and 34.6%, respectively; however, the difference did not seem to be statistically significant (P = .093). The disease control rate was 20.0% with antibiotics and 57.7% without antibiotics (P = .008).

“As the role of immune checkpoint inhibitors in the treatment of metastatic urothelial carcinoma continues to grow, an understanding of the factors that positively or negatively affect treatment efficacy is clinically important,” the investigators explained.

Disclosure: For full disclosures of the study authors, visit

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