Distinguishing between help and harm: Helper T cell subsets and immune-related adverse events.

The precise conditions by which cytokines drive cancer is relevant to improving immune checkpoint inhibition (ICI) responses while decreasing toxicity. In this issue of the JCI, Kao et al. investigated T helper cell pathways in patients with solid tumors receiving ICI. The authors evaluated T cell populations, cytokine signatures, immune related adverse events (irAEs), and survival outcomes. Patients with a history of autoimmune disorders were more likely to develop irAEs. Notably, blood samples from patients on treatment showed that elevations in IL-5, IL-6, IL-17f, and TNF-α were associated with an increased risk for grade 2 or higher irAEs. Moreover, IL-6 was associated with decreased objective response rate and worse cancer-specific and all-cause mortality. These findings may help guide decisions for optimizing ICI efficacy while minimizing toxicity and suggest that IL-6 blockade may improve response and decrease toxicity in solid tumors.