An international study has demonstrated that the microbiota and the intestinal cell death triggered by chemotherapy stimulate the efficacy of the immune response in patients with colorectal cancer. The results of the study, conducted in France by scientists from Gustave Roussy, Inserm, Université Paris-Saclay, the Institut Pasteur, IHU Méditerranée Infection and INRAE, were published in the journal Nature Medicine. The scientists offer new insights that shed light on the mechanisms governing positive or negative responses to cancer treatments.