Cryoablation Plus Immune Checkpoint Inhibitors Enhanced Dendritic Cell and T Cell Activation in TNBC Murine Model

Purpose: Cryoablation eradicates tumors through repeated freeze-thaw cycles and preserves tumor-associated antigens, triggering inflammatory signals capable of priming anti-tumor immunity, yet its therapeutic potential in triple-negative breast cancer (TNBC) remains largely unexplored. Immune checkpoint inhibitors (ICIs) have shown clinical benefit in TNBC but come with significant immune-related toxicities. Combining cryoablation with ICIs in TNBC may amplify the efficacy of cryoablation, which is significantly less toxic than ICIs, thereby providing opportunities for lowering the doses of ICIs in clinical practice. Here, we investigated the therapeutic impact of cryoablation with ICIs in an orthotopic bilateral murine TNBC model. Methods: Two weeks after tumor induction, primary tumors were cryoablated while the abscopal tumors were not manipulated and represented distant tumors. Twenty-four hours pre- and post-cryoablation, mice received an intra-peritoneal injection of PBS or ICIs (anti-CTLA-4, PD-1, or PD-L1). Tumors, tumor-draining lymph nodes (TdLNs), spleen, and peripheral blood were assessed for immune profiling a week later. Results: Preliminary analyses demonstrated that combining cryoablation with anti-CTLA-4 enhanced T cell activation systemically compared to cryoablation alone or in combination with PD-1/PD-L1 blockade. Notably, relative to cryoablation monotherapy, combination with anti-CTLA-4 increased the frequencies of activated CD4⁺ and CD8⁺ T cells in the abscopal tumors, while also inducing a higher frequency and activation of conventional dendritic cells in the abscopal TdLNs. Conclusion: These results suggest combination of cryoablation with anti-CTLA-4 therapy enhances systemic antitumor immunity by boosting antigen presentation. Our results support further investigation into this combination strategy to prevent tumor recurrence and metastasis while minimizing toxicity of treatment.