Interventional radiology for local immunotherapy in oncology.

Human intratumoral immunotherapy (HIT-IT) is under rapid development with promising preliminary results and high expectations for current phase 3 trials. While outcomes remain paramount for patients and the referring oncologists, the technical aspects of drug injection are critical to the interventional radiologist in order to ensure optimal and reproducible outcomes. The technical considerations for HIT-IT impact the safety, efficacy and further development of this treatment option. Image-guided access to the tumor allows to enhance the therapeutic index of a treatment by increasing the intra-tumoral drug concentration while minimizing its systemic exposure and associated on-target off-tumor adverse events. Direct access to the tumor also enables the acquisition of cancer tissue for sequential sampling in order to better understand the pharmacodynamics of the injected immunotherapy and its efficacy through correlation of immune responses, pathological responses and imaging tumor response. The aim of this review is to share the technical insights of HIT-IT, with particular consideration for patient selection, lesion assessment, image-guidance, and technical injection options. In addition, the organization of a standard patient workflow is discussed, so as to optimize HIT-IT outcome and the patient experience.