Abstract C021: Cryo-Immune Vaccination (CIV): A locoregional device/multidrug immunotherapeutic approach that can bypass toxicity yet systemically eradicate metastatic cancers

Abstract A major challenge to further development of immune checkpoint therapies (ICT) for advanced cancer is the inherent toxicity of higher-order multidrug combinations likely needed to eradicate metastatic disease. Recently, early clinical studies have investigated a new general approach to address this challenge, which we have termed cryo-immune vaccination (CIV). The CIV approach involves monthly cycles of local cryolysis of different solid tumors in a metastatic patient, creating multiple personalized neoantigen vaccines, followed by infusion of the cyrolysed tumors with low-dose multi-API formulation. A recent Phase I clinical study of SYNC-T therapy, the first clinical iteration of the CIV approach to be studied in patients, has demonstrated safety and efficacy in producing a striking systemic clearance of both treated and non-treated tumors in patients with metastatic prostate cancer. As trials of SYNC-T therapy proceed, we have modeled CIV in preclinical models to help illuminate its mechanistic foundations – particularly to understand how CIV manages to achieve systemic responses by invoking host-mediated eradication of untreated metastatic lesions. We developed a conceptual framework for CIV study in the orthotopic 4T1 model of metastatic breast cancer. When primary tumors reach ∼5-7 mm, a time when occult pulmonary metastases have already seeded, primary tumors are exposed surgically on skin flaps, contacted with a liquid nitrogen-cooled pointed steel rod for 15-30 sec, thawed briefly, and then injected with an ICT multidrug cocktail or negative control murine IgG. The founding drug cocktail modeled the SYNC-T combination therapy SV-102, currently under study in the LEGION-100 trial in patients with metastatic prostate cancer (Syncromune, Inc.), included murine-reactive antibodies against CTLA4, PD-1 or OX40 (agonist), CD40 (agonist), and CpG oligonucleotide. Our work has revealed several insights into CIV efficacy in the 4T1 model. First, while the therapy is inefficacious in WT subjects it is curative in Ido1–/– hosts, suggesting that Ido1 blockade may can improve systemic efficacy against untreated metastatic lesions. Second, drug omission experiments suggest that ICT antibodies are critical to drive survival, with the CD40 antibody less important. In anti-CD40 substitution experiments, Lag3 antibody was identified as a potent in contributing to efficacy. Third, CD8+ T cells harvested from cured 4T1-bearing subjects were sufficient for exerting antitumor activity in naïve 4T1-bearing subjects. Lastly, mice cured of metastatic 4T1 tumors were not only resistant to rechallenge with 4T1 cells but also to challenge by EMT6, a different breast cancer model, as well as CT-26, a model of colon cancer, suggesting robust neoantigen spreading and a large number of metastasis-fighting T cell clones unleashed by CIV therapy (as observed clinically with SYNC-T therapy). Ongoing T cell clonal analysis is being pursued to explain the unusual finding of multi-histological tumor resistance in subjects cured of the original 4T1 breast cancer. Citation Format: James B. DuHadaway, Alexander J. Muller, Lisa D. Laury-Kleintop, U. M. Wallon, Marie Webster, Jason Williams, Gabriela R. Rossi, Mario R. Mautino, Charles J. Link, George C. Prendergast. Cryo-Immune Vaccination (CIV): A locoregional device/multidrug immunotherapeutic approach that can bypass toxicity yet systemically eradicate metastatic cancers [abstract]. In: Proceedings of the AACR Immuno-Oncology Conference (AACR IO): Discovery and Innovation in Cancer Immunology: Revolutionizing Treatment through Immunotherapy; 2026 Feb 18-21; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Immunol Res 2026;14(2 Suppl):Abstract nr C021.