Inhibiting B cells enhances the efficacy of STING agonism or immune checkpoint blockade in hepatocellular carcinoma

Most patients with hepatocellular carcinoma (HCC) develop resistance to immune checkpoint blockade (ICB) or STING agonists despite their immune-stimulating activities. Here, we identify increased intratumoral B-cell infiltration as a mediator of acquired resistance. In HCC models with liver fibrosis in male mice, anti-PD-1 ICB or the STING agonist BMS-986301 increase intratumoral B-cell infiltration, circulating IL-10, and TIM-1+ B-cells, promoting tertiary lymphoid structure formation. B-cell depletion combined with ICB or STING agonism improves survival, and STING agonism inhibits distant metastasis. In addition, co-targeting STING and TIM-1 enhances B-cell differentiation and antigen presentation, reduces intratumoral TIM-1+ B-cells, and increases CD86 and MHC class II expression, thereby augmenting CD8+ T-cell-mediated anti-tumor immunity. These findings reveal that B-cells contribute to ICB and STING therapy resistance in HCC, and that B-cell depletion or TIM-1 blockade can overcome acquired resistance to these immunotherapies. B cell subsets expanding during tumor progression have been associated with impaired anti-tumor responses and resistance to immunotherapy. Here the authors report that STING agonism or anti-PD-1 induce intratumoral B cell infiltration, and that depleting B-cells improves response to immunotherapies in preclinical models of hepatocellular carcinoma.