Scientists in the U.K., Switzerland, and Italy have shown how a type of immunotherapy that is undergoing trials for treating psoriasis also renders advanced prostate cancer responsive to hormone therapy. The researchers’ studies in human tissue and in a mouse model found that castration-resistant prostate cancer (CRCP) is driven by interleukin-23 (IL-23) produced by immune cells called myeloid-derived suppressor cells (MDSCs). Treating mice with androgen deprivation therapy (ADT)-resistant prostate tumors using an antibody that blocked IL-23 reactivated the tumors’ responsiveness to the androgen receptor antagonist (AR), enzalutamide (ENZA). Tumors shrank in mice receiving both the anti-IL-23 and enzalutamide therapy, and the animals also lived longer than control mice. “Our study found an important interaction between hormone signaling and the immune system,” comments Johann de Bono, M.D. Regius Professor of Cancer Research at the Institute for Cancer Research (ICR) in London, which headed the studies in collaboration with colleagues ...