IRF4 promotes immune evasion and shapes the tumor microenvironment in Follicular Lymphoma.

Twenty percent of follicular lymphoma (FL) patients relapse early with poor outcomes; however, the molecular mechanisms underlying this aggressive behavior are unknown. Using a multi-omics approach, we show that FL patients with elevated IRF4 expression (IRF4hi) have increased transformation risk, dysregulated immune signaling, and a suppressive tumor microenvironment. Loss- and gain-of-function experiments in IRF4hi lymphoma cells, along with chromatin profiling, demonstrate that IRF4 impairs their interaction with T cells by repressing antigen presentation and co-receptor gene modules, while promoting the expression of cytokines that antagonize TFH and Treg functions. Additionally, IRF4 rewires tumor metabolism which restricts glucose availability to immune cells. Silencing of IRF4 inhibits tumor cell growth and restores immune surveillance mechanisms, thus representing a promising target for therapy. Our data suggest that IRF4hi lymphoma cells co-opt a developmental mechanism used to exit the germinal center response in promoting a more aggressive cancer via engagement of multiple immune-evasive mechanisms.