Intratumoral Immunotherapy and Tumor Ablation: A Local Approach with Broad Potential

SIMPLE SUMMARY: The goal of immuno-oncology is to potentiate a durable antitumor immune response. The immunosuppressive tumor microenvironment (TME) presents a substantial challenge to current systemic therapies due in part to a lack of available tumor antigen, dense stroma, an abundance of immunosuppressive cells and cytokines, and poor antigen presentation. A multimodal approach that combines intratumoral immunotherapy with tumor ablation addresses several of these challenges. In this review, we evaluate the current data regarding this promising therapeutic approach. ABSTRACT: Several intratumoral immunotherapeutic agents have shown efficacy in controlling local disease; however, their ability to induce a durable systemic immune response is limited. Likewise, tumor ablation is well-established due to its role in local disease control but generally produces only a modest immunogenic effect. It has recently been recognized, however, that there is potential synergy between these two modalities and their distinct mechanisms of immune modulation. The aim of this review is to evaluate the existing data regarding multimodality therapy with intratumoral immunotherapy and tumor ablation. We discuss the rationale for this therapeutic approach, highlight novel combinations, and address the challenges to their clinical utility. There is substantial evidence that combination therapy with intratumoral immunotherapy and tumor ablation can potentiate durable systemic immune responses and should be further evaluated in the clinical setting.