Sensitization of ovarian tumor to immune checkpoint blockade by boosting senescence-associated secretory phenotype.

Therapy-induced senescence-associated secretory phenotype (SASP) correlates with overcoming resistance to immune checkpoint blockade (ICB). Intrinsic resistance to ICB is a major clinical challenge. For example, ovarian cancer is largely resistant to ICB. Here we show that adoptive transfer of SASP-boosted therapy-induced senescent cells sensitizes ovarian tumor to ICB. Topoisomerase 1 (TOP1) inhibitors such as irinotecan enhance cisplatin-induced SASP, which depends on the TOP1 cleavage complex-regulated cGAS pathway. Significantly, intraperitoneal transfer of cisplatin-induced, SASP-boosted senescent cells with irinotecan sensitizes ovarian tumor to anti-PD-1 antibody and improves the survival of tumor-bearing mice in an immunocompetent, syngeneic model. This correlates with the infiltration of transferred senescent cells in the established orthotopic tumors and an increase in the infiltration of activated CD8 T cells and dendritic cells in the tumor bed. Our findings indicate that adoptive transfer of SASP-boosted therapy-induced senescent cells represents a potential therapeutic strategy to sensitize tumors to ICB.