Intratumoural immunotherapy plus focal thermal ablation for localized prostate cancer

Major advances have been made in the use of immunotherapy for the treatment of solid tumours, including the use of intratumourally injected immunotherapy instead of systemically delivered immunotherapy. The success of immunotherapy in prostate cancer treatment has been limited to specific populations with advanced disease, which is thought to be a result of prostate cancer being an immunologically 'cold' cancer. Accordingly, combining intratumoural immunotherapy with other treatments that would increase the immunological heat of prostate cancer is of interest. Thermal ablation therapy is currently one of the main strategies used for the treatment of localized prostate cancer and it causes immunological activation against prostate tissue. The use of intratumoural immunotherapy as an adjunct to thermal ablation offers the potential to elicit a systemic and lasting adaptive immune response to cancer-specific antigens, leading to a synergistic effect of combination therapy. The combination of thermal ablation and immunotherapy is currently in the early stages of investigation for the treatment of multiple solid tumour types, and the potential for this combination therapy to also offer benefit to prostate cancer patients is exciting. In this Review, the authors examine the potential synergy between thermal ablation and intratumoural immunotherapy in treating localized prostate cancer. This combination could transform the traditionally cold immunological landscape of prostate cancer into a hot one, enhancing treatment efficacy. Intratumourally delivered immunotherapy has less systemic adverse effects than systemically delivered immunotherapy. The structure of the prostate seems well-suited to the intratumoural delivery of immunotherapy.Prostate cancer is typically an immunologically cold tumour, but thermal ablation treatment could make prostate cancer an immunologically hot tumour.The combination of intratumoural immunotherapy with thermal ablation therapy for the treatment of prostate cancer could work synergistically because ablation therapy reveals prostate cancer-specific antigens to the immune system.Animal models and early clinical trials have been used to investigate the combination of immunotherapy and thermal ablation for solid tumours, but further investigation is needed for the treatment of prostate cancer.