Cryoablation could be used to augment the effect of immune checkpoint inhibition (ICI) in prostate cancer, according to a preclinical study.

ICI has shown only moderate efficacy in prostate cancer, despite FDA approval in other malignancies. However, an abscopal effect has been proposed. Benzon and colleagues studied this potential effect using a combination of cryoablation and ICI. After establishing synchronous grafts in FVB/NJ mice, the mice received anti-PD1 (10 mg/kg), anti-CTLA4 (1 mg/kg), or a control antibody with or without adjuvant cryoablation of the larger tumour graft and with or without neoadjuvant degarelix. Although cryoablation of the larger tumour delayed growth acceleration in the untreated graft, with a nearly eightfold reduction in mortality, the combination of PD1 blockade and cryoablation did not have a synergistic effect compared with cryoablation alone. However, cryoablation did seem to synergize with anti-CTLA4, delaying growth acceleration and decreasing mortality fourfold compared with cryoablation alone. Depletion of CD3+ or CD8+ cells completely neutralized the beneficial effects of the combination, suggesting that the effect is T cell-dependent. Trimodal therapy using degarelix, PD1 blockade, and cryoablation almost doubled tumour growth delay and survival in 25% of treated mice compared with bimodal therapy with degarelix and cryoablation, also in a T cell-dependent manner.

Further studies will determine whether trimodal therapy (androgen ablation, cryoablation, and PD1 blockade), or combined cryoablation and low-dose anti-CTLA4, could have a role in prostate cancer treatment.