Scientists found why cancer immunotherapy sometimes turns on the patient — and a high-fibre diet calmed it in mice

Immunotherapy can melt cancers, but in up to 40% of patients the same immune surge attacks healthy tissue, and there is no approved treatment for the side effects themselves. A University of Pittsburgh team, publishing in Cell, built a first-of-its-kind mouse model fed a human-like Western diet — low fibre, high fat — and traced the problem to 'fragile' regulatory T cells, the immune system's peacekeepers; the same fragility showed up in patients with severe side effects. Steadying those cells — by blocking a signalling protein, switching to a high-fibre diet, or adding a gut metabolite — reduced the damage in mice. Human treatments are still to come, but the target now has a name.

SDG 3 · Good health and well-being — Mechanism: tech innovation