Over the past 10–15 years, immunotherapy—drugs that reactivate the immune system against cancer—has revolutionized the treatment of many malignancies, including kidney cancer. However, a substantial proportion of patients either fail to respond, or obtain only limited benefit. Growing evidence suggests that the intestinal microbiota plays a crucial role in both cancer development and in the response to immunotherapy.

“The gut microbiota is known to influence the immune system, and in kidney cancer several factors—such as marked angiogenesis and inflammatory mediators like IL-6—can reduce the effectiveness of immunotherapy,” explains Professor Giampaolo Tortora, Full Professor of Medical Oncology at Università Cattolica del Sacro Cuore and Director of the Comprehensive Cancer Center at Fondazione Policlinico Gemelli IRCCS.