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.

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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].”


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.