There is a significant association between antibiotic use and unfavorable clinical outcomes in cancer patients receiving immune checkpoint inhibitors (ICI), according to a meta-analysis presented at IDWeek, held virtually October 21 to 25, 2020.

Investigators reviewed 41 studies evaluating the association between antibiotic use and clinical outcomes in cancer patients treated with ICI. These studies included 10,857 patients, and the most common malignancies were lung cancer (59.7%), melanoma (23.1%), and renal cell and urothelial carcinomas (8.1%). Primary outcomes measured were overall survival (OS), progression-free survival (PFS), response rate (RR), and progressive disease (PD) rate.

In patients receiving antibiotics, OS (adjusted hazard ratio [aHR], 1.87; 95% CI, 1.55-2.25; P <.001) and PFS (aHR, 1.52; 95% CI, 1.36-1.70; P <.001)) were shorter, RR (odds ratio [OR], 0.54; 95% CI, 0.34-0.86; P <.001) was lower, and PD rate (OR, 2.00; 95% CI, 1.27-3.14; P =.001) was higher, even after adjustments for other confounders. Antibiotic use was associated with worse OS (aHR, 1.88; 95% CI, 1.59-2.22; P =.002) and PFS (aHR, 1.93; 95% CI, 1.59-2.36; P =.006) after pooling hazard ratios and adjusted hazard ratios. While heterogeneity was significant for all outcomes, it was less significant for adjusted OS and PFS.

Subgroup analyses found a strong association between antibiotics with progression free survival in patients with renal cell carcinoma or melanoma compared to lung cancer patients. Study results revealed that only when patients were receiving antibiotics more than 1 month after ICI administration was it associated with increased disease progression.


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“To our knowledge, this is the largest meta-analysis on associations between antibiotic use and the efficacy of ICI, and the only one to address RR and PD to date,” according to investigators. They conclude that this patient group may be an important target for antibiotic stewardship interventions and that the high heterogeneity across all outcomes “underscores the need for more detailed, patient-level studies with stratification by host, antibacterial, and cancer treatment factors.”

Reference

Tsikala-Vafea M, Belani N, Vieira K, Farmakiotis D. The impact of antibiotic use on clinical outcomes in cancer patients treated with immune checkpoint inhibitors: a systematic review and meta-analysis. Presented at: IDWeek 2020; October 21-25, 2020. Poster 191.