Immune-adjuvant loaded Bi2Se3 nanocage for photothermal-improved PD-L1 checkpoint blockade immune-tumor metastasis therapy

Checkpoint blockade based immune therapy has shown to be effective but benefit only the minority of patients whose tumors have been pre-infiltrated by T cells. To overcome this obstacles, a PEG-modified Bi2Se3 nanocage (NC) loaded with imiquimod (R848), which could efficiently destroy the tumors thus producing enough tumor-associated antigens (TAA) and with the existence of R848, a toll-like-receptor-7 agonist, could generate strong anti-cancer immune responses is reported in this study. Moreover, immunogenic Bi2Se3 NC-PEG/R848 mediated photothermal therapy (PTT) sensitizes tumors to checkpoint inhibition mediated by a PD-L1 antibody, not only ablating cancer cells upon NIR laser but also causing strong anti-cancer immunity to suppress distant tumor growth post PTT. Both in vitro and in vivo experiments demonstrate that the Bi2Se3 NC-PEG/R848 could effectively activate a PTT-induced immune response as well as silence immune resistance based on PD-L1 checkpoint blockade to ablate the primary tumor and further inhibit the tumor metastasis. Bi2Se3 NC reported here exhibits high photothermal conversion efficiency and stability, as well as competent drug loading capacity with large hollow structures and high surface area. Our study not only provides a facial way to synthesize Bi2Se3 NC, but also offers an alternative strategy for tumor metastasis.