Evaluating the Impact of Adjunctive Partial Cryoablation on Dual Checkpoint Inhibitor Immunotherapy Response in a Murine Model.

Purpose To evaluate the impact of adjunctive partial cryoablation on checkpoint inhibitor (CPI) immunotherapy response. Materials and Methods One hundred fifty-six mice (equal number of male and female animals) with dual-implanted tumor models were treated with dual CPI or a vehicle and randomized to treatment of a single tumor with partial cryoablation. Tumors were followed for 60 days following cryoablation for response assessment. In additional groups, the tumor microenvironment was characterized via flow cytometry, cytokine analysis, and immunohistochemistry. Statistical comparison was made between the different treatment groups regarding T-cell infiltration and activation characteristics within the noncryoablated tumor and cytokine levels within the partially ablated tumor. Additionally, qualitative assessment of T-cell activation within the cryoablated and noncryoablated tumors at immunofluorescence was carried out. Results At 60 days following treatment, CPI and adjunctive cryoablation-treated MC-38 mice had a significantly increased survival rate (79%) compared with mice treated with CPI alone (61%;