Improving anti-PD-L1 therapy in triple negative breast cancer by polymer-enhanced immunogenic cell death and CXCR4 blockade

Triple negative breast cancer (TNBC) with highly metastatic features generally does not respond to anti-programmed cell death 1 ligand 1 (PD-L1) therapy due to multiple immunosuppressive mechanisms to exclude and disable T cells. Here, we develop a polymer-based combinatory approach consisting of both immunogenic cell death (ICD)-inducing and CXCR4-inhibiting function to prime tumor microenvironment and improve antiPD-L1 therapy in TNBC. Our findings revealed that the combination therapy was able to spur the T cell response in primary tumors by increasing the tumor immunogenicity to recruit T cells, removing the physiological barriers of intratumoral fibrosis and collagen to increase T cell infiltration, and reducing the immunosuppressive cells to revive T cells. Meanwhile, such approach efficiently inhibited the formation of pre-metastatic niche in abscopal lung. Because of the significant promotion of anti-tumor and anti-metastasis immunity, the non-responding TNBC gained robust responsiveness to anti-PD-L1 therapy which resulted in complete eradication of orthotopic tumors, inhibition of pulmonary metastasis, and durable memory effects against tumor recurrence. Our work provided a generalizable approach of simultaneous ICD induction and CXCR4 blockade to apply anti-PD-L1 therapy in TNBC.