GFRAL-Fc disarms GDF15 to reprogram tumor immunity and amplify PD-1 efficacy in hepatocellular carcinoma.

[BACKGROUND] Checkpoint inhibitors have revolutionized hepatocellular carcinoma (HCC) treatment, yet their efficacy remains limited in advanced stages, with suboptimal objective response rates. Growth differentiation factor 15 (GDF15), a dual-functional cytokine implicated in tumor progression and immunosuppression, represents a promising therapeutic target. This study aims to develop a novel GDF15-targeted strategy to improve HCC management and synergize with PD-1 blockade.

[METHODS] GFRAL-Fc fusion proteins were generated by fusing the extracellular domain of GFRAL with IgG1 Fc. The anti-tumor efficacy and the anti-cachexia ability of GFRAL-Fc was evaluated in a spontaneous HCC model on GDF15 humanized mice. Additionally, the half-life and drug safety were evaluated in mice. To investigate the underlying mechanisms, a CyTOF analysis was utilized to analysis the immunoregulation effects of GFRAL-Fc within HCC. Finally, the anti-tumor effects of GFRAL-Fc in combination with Programmed Death-1 (PD-1) inhibitors were assessed.

[RESULTS] GFRAL-Fc targets GDF15 to simultaneously prevent GDF15-CD48 interaction-driven ERK activation and block GDF15-GFRAL binding. Treatment with GFRAL-Fc achieved dual antitumor effects: reducing tumor progression and attenuating cancer-associated cachexia. Combination with PD-1 blockade further enhanced antitumor efficacy, resulting in a substantial decrease in tumor nodules. Mechanistic studies revealed that GFRAL-Fc reprograms the immunosuppressive tumor microenvironment by suppressing Treg activation while enhancing CD8 T cell cytotoxicity.

[CONCLUSIONS] Our findings validate GDF15 targeting as a viable strategy to overcome checkpoint inhibitor resistance in HCC. The GFRAL-Fc fusion protein demonstrates multimodal therapeutic benefits through metabolic regulation and immune remodeling, providing a clinically translatable approach to optimize PD-1-based regimens. This study addresses critical gaps in current HCC management and warrants further clinical validation.