Tumor Microenvironment in Adrenocortical Carcinoma: Barrier to Immunotherapy Success?

Simple Summary Adrenocortical carcinoma is a rare but aggressive malignancy with poor outcomes even for patients with early-stage disease. Several immunotherapy clinical trials, many of which are still in progress, have yielded modest results so far. In-depth understanding of the tumor microenvironment in other cancer types has helped the scientific community to identify novel therapeutic targets and gain a better insight of cancer biology. The present review aims to provide an update of the current knowledge regarding adrenocortical carcinoma tumor microenvironment and describe how the latter potentially affects patient response to immunotherapy. Following the paradigm of other cancer types, exploiting tumor microenvironment could open new therapeutic avenues. Abstract Adrenocortical carcinoma is a rare malignancy with aggressive behavior, with up to 40% of patients presenting with metastases at the time of diagnosis. Both conventional chemotherapeutic regimens and novel immunotherapeutic agents, many of which are currently being tested in ongoing clinical trials, have yielded modest results so far, bringing the need for a deeper understanding of adrenal cancer behavior to the forefront. In the recent years, the tumor microenvironment has emerged as a major determinant of cancer response to immunotherapy and an increasing number of studies on other solid tumors have focused on manipulating the microenvironment in the favor of the host and discovering new potential target molecules. In the present review we aim to explore the characteristics of adrenocortical cancer’s microenvironment, highlighting the mechanisms of immune evasion responsible for the modest immunotherapeutic results, and identify novel potential strategies.