The gut wall’s potential as a partner for precision oncology in immune checkpoint treatment

•Gut microbiota impacts tumor response to immune checkpoint inhibitors (ICI).•The potential role of the gut wall regarding the tumor response to ICI has received little attention.•Selective markers can define gut wall integrity and the intestinal immune system.•Clinical interventions are available that modify key components of the gut wall.•The gut wall’s potential to improve ICI efficacy should be further explored.