A study presented at the American Society of Clinical Oncology (ASCO) Genitourinary Cancers Symposium, held February 16–18 in Orlando, USA, suggests that antibiotics administered less than a month before starting PD-1 or PD-L1 immune checkpoint inhibitor therapy for patients with advanced kidney cancer might impair control of tumour growth.

“Recent use of antibiotics prior to immune checkpoint inhibitor therapy negatively influences outcomes,” noted lead study author Dr Lisa Derosa of the Gustave Roussy Cancer Institute, Paris-Sud University in Villejuif, France. “These early findings show that doctors prescribing cancer immunotherapy should pay closer attention to antibiotic use.”

The effect of recent antibiotic use might be due to specific microbes (bacteria) in the gut. Research has suggested that gut bacteria can interact with immune system cells in mice to improve the anti-tumour activity of  immune checkpoint inhibitors. The researchers are now investigating the biological mechanisms underlying the association between antibiotics and immune checkpoint inhibitors and further studies are needed to better understand how alteration of gut microbes affects immunotherapy outcomes.

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