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 III trials. While outcomes remain paramount for patients and the referring oncologists, the technical aspects of drug injection are critical to the interventional radiologist to ensure optimal and reproducible outcomes. The technical considerations for HIT-IT affect the safety, efficacy, and further development of this treatment option. Image-guided access to the tumor allows the therapeutic index of a treatment to be enhanced by increasing the intratumoral 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 to better understand the pharmacodynamics of the injected immunotherapy and its efficacy through correlation of immune responses, pathologic responses, and imaging tumor response. The aim of this article 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.