Immune checkpoint inhibitor related adverse effects and imaging findings

ABSTRACT

Learning Objectives: To educate the general radiologist about imaging findings related to common and important irAEs they may encounter as the treatment of cancers with ICIs becomes more common. Background: Over the past decade or so, there has been a growth in the treatment of a variety of cancers with immunotherapy, in particular immune checkpoint inhibitors (ICIs). ICIs work by inhibiting the signal pathways responsible for the suppression of T-cell mediated tumor destruction, which leads to increased activation of the immune system (1). This is responsible for the therapeutic effect of these agents, but also the reason for adverse events related to autoimmunity referred to as immune-related adverse events (irAEs) (1-3). Due to the increased utilization of ICIs and the integral role of imaging in cancer care, radiologists must be aware of these types of treatments, their treatment response patterns and their adverse side effects, which may differ from conventional chemotherapies. This is particularly pertinent given increased utilization of telehealth related to the covid-19 pandemic, which has seen a shift towards performing more oncologic imaging in the community rather than in tertiary referral centres. Imaging Findings OR Procedure Details The timely identification and management of irAEs is important as they can be potentially life threatening, and the radiologist may be the first to identify irAEs based on the imaging appearances (2). The clinical presentation is often nonspecific, and imaging plays a key role in distinguishing between irAEs and progression of metastatic disease. Imaging findings may also precede symptoms. This educational presentation describes and illustrates the imaging findings of some of the most common and most important irAEs such as pneumonitis, colitis, hypophysitis, hepatitis and sarcoid like reaction, using imaging examples from our tertiary referral centre and a multi-modality approach. Conclusion: Imaging plays an integral role in cancer care and the use of ICIs is increasing. It is important for the radiologist to be aware of the imaging findings of irAEs, in order to distinguish these from disease progression and prompt timely clinical management.