Antihistamines for cancer immunotherapy: More than just treating allergies.

Summary In this issue of Cancer Cell, Li et al. show that histamine released in allergic reactions and from tumor cells attenuates immunotherapy response. Histamine H1-receptor (H1R) signaling induces an M2-like phenotype in tumor-associated macrophages and increases VISTA expression, suppressing CD8+ T cell function. Antihistamines reverse these effects and improve the efficacy of immunotherapy.