Tumor cryoablation: Preclinical models and methods to explore immunological effects

Cryotherapy is a device-based modality used to treat certain localized cancers, including cancers of the breast, prostate, liver and skin. This therapeutic approach is based on image-guided placement into a tumor of a needle-like probe that generates ultra-cold conditions at the probe tip to destroy tumor tissue and grossly inflame the local tissue microenvironment. Necrotic and osmotic cell deaths triggered by this local freeze-thaw process enable immune exposure of non-denatured tumor neoantigens released as a result of the tumor ablation. Notably, there is evidence that cryotherapy can exert vaccine-like effects, triggering antitumor immune signals beyond the locally treated tumor that are analogous to the abscopal effects of cancer radiotherapy. Accordingly, there is growing interest in device/drug studies to capture and leverage cryotherapy in combination with immune checkpoint antibodies and/or other immunostimulatory agents for cancer immunotherapy. Here we describe the development of a preclinical mouse model and methods to help elucidate the immunogenic effects of tumor cryoablation, based on an adaptation of the orthotopic metastatic breast cancer model 4T1 to focus on mechanisms of cryo-immunology and their potential implications for treating localized or systemic malignancy.