This article originally appeared in Cancer Therapy Advisor.

Antibiotics may indirectly improve progression-free survival (PFS) among patients with metastatic renal cell carcinoma (RCC) receiving a first-line VEGF–tyrosine kinase inhibitor (TKI), according to research being presented at the 2018 Genitourinary Cancers Symposium in San Francisco, California.

Patients receiving VEGF-TKIs are likely to have treatment dose reductions, delays, or interruptions because of diarrhea, which occurs in approximately 50% of cases. Diarrhea is, furthermore, directly linked to stool bacteroides levels.

For this retrospective study, researchers evaluated whether incidentally prescribed antibiotics would reduce the likelihood of treatment delays, interruptions, and dose reductions, indirectly improving PFS among patients with metastatic RCC receiving a first-line VEGF-TKI.

One hundred and forty-five patients were included; each had intermediate- (123 patients) or poor-risk (22 patients) disease. Eighteen patients were incidentally prescribed antibiotics targeting bacteroides; 13 had high sensitivity for bactericides.

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Among patients prescribed antibiotics with bacteroides sensitivity, the median PFS was 18 months. Patients prescribed antibiotics without bacteroides sensitivity had a median PFS of 9 months, and patients not prescribed antibiotics had a median PFS of 8 months.

The authors concluded that while validation is needed, in “these hypothesis generating data, incidental targeting of stool bacteroides with [incidental antibiotics] correlated with improved PFS in [metastatic] RCC patients on [first-line VEGF-TKIs].”

Reference

VanAlstine S, Froerer C, Hahn AW, et al. Targeting bacteroides in the stool microbiome and response to treatment (Rx) with first-line VEGFTKI in metastatic renal cell carcinoma (mRCC). Oral presentation at: 2018 Genitourinary Cancers Symposium; February 8-10, 2018; San Francisco, CA.