Focal therapeutic conditions matter: How energy affects antigen presentation and T cell activation

Energy-based minimally invasive cancer focal therapies (FTs), including thermal ablation (Heat), cryoablation (Cryo), and irreversible electroporation (IRE), can induce immunomodulatory effects and can synergize with immunotherapy to engage the immune system for systemic and long-term antitumor response. However, the immunogenicity of each FT can vary based on treatment specifics, and the mechanisms underlying these differences are not fully understood. We employed a model antigen (ovalbumin, OVA) and an in vitro platform to investigate the upstream processing steps that initiate immune priming. This platform enabled quantitative assessment of antigen release, antigen presentation, dendritic cell (DC) activation, antigen-specific T cell proliferation and the generation of damage-associated molecular patterns (DAMPs), cytokines and chemokines. Both antigen-specific signaling and T cell response are highly dependent on the focal therapeutic conditions applied to the cancer cells. Cryo resulted in the highest release of protein, OVA antigen, ATP, and HMGB1, followed by IRE and Heat. Despite not yielding the most antigen, IRE-treated B16-OVA elicited the most DC activation and OVA-specific T cell proliferation. Dose-response analysis using OVA protein and SIINFEKL peptide confirmed a positive correlation between antigen availability and T cell response. We also observed substantial adjuvant effects that enhance the immune processing and T cell response by stimulus in cell lysates independently of antigen quantity. Specifically, IRE-treated B16 cell lysates induced the most significant improvement in dendritic cell (DC) activation and T cell proliferation compared to Heat and Cryo when paired with equal amounts of antigen. Our findings position IRE as the most immunogenic FT condition in our system. This study highlights the critical interplay between antigen release, adjuvant signals, and immune processing in shaping FT-driven antitumor immunity.