Overcoming CXCR4-mediated T cell exclusion potentiates antitumor cytotoxicity in fibrolamellar carcinoma

Fibrolamellar carcinoma (FLC) is a rare liver cancer affecting young adults without underlying liver disease and is characterized by the DNAJB1-PRKACA fusion oncogene. Despite its immunogenicity, FLC shows limited response to immunotherapy. To investigate the mechanisms of immune resistance, we performed single-nucleus RNA sequencing on human FLC and matched adjacent non-tumor liver samples. Our analyses revealed dysregulated stromal-immune interactions, including CXCL12+ myofibroblast signaling that restricted T cell infiltration. Using complementary approaches, we found that CXCR4 inhibition enabled T cell entry into tumors, while PD-1 blockade enhanced T cell effector function. Combination treatment synergistically increased tumor cell death in a human tumor slice culture system. These results define mechanisms of immune evasion in FLC and provide preclinical support for combined CXCR4 and PD-1 blockade as a potential therapeutic strategy.