Imaging of Adverse Events Related to Checkpoint Inhibitor Therapy

Abstract

Immunotherapy with checkpoint inhibitors (ICIs) is becoming standard of practice for an increasing number of cancer types. ICIs enhance T-cell action against the cancer cells. By unbalancing the immune system ICIs may cause dysimmune toxicities, a series of disorders broadly defined immune-related adverse events (irAEs). IrAEs may affect any organ or apparatus and most frequently involve skin, colon, endocrine organs, liver, and lungs. Early identification and appropriate treatment of irAEs can improve patient outcome. The paper aims at reviewing mechanisms of the occurrence of irAEs, the importance of a proper diagnosis and the main pillars of therapy. To provide effective guidance to the comprehension of major irAEs imaging findings will be reviewed.

Adverse Effects of Immune-Checkpoint Inhibitors: A Comprehensive Imaging-Oriented Review

“…Differential diagnosis includes idiopathic autoimmune hepatitis, viral hepatitis, and alcoholic liver disease [45].…”

Immune Checkpoint Inhibitor–Related Adverse Effects and18F-FDG PET/CT Findings

“…These medications are called immune checkpoint inhibitors (ICIs). Currently approved ICI medications block cytotoxic T-lymphocyteassociated protein 4 (ipilimumab), programmed death receptor 1 (pembrolizumab, nivolumab), or its ligand (atezolizumab, avelumab, durvalumab, and cemiplimab) (4,6). These medications are approved to be used in the treatment of various cancers such as melanoma (ipilimumab, nivolumab, pembrolizumab), non-small cell lung cancer (pembrolizumab, nivolumab), renal cancer (nivolumab, ipilimumab), and bladder cancer (atezolizumab) (4,6).…”

“…On unenhanced CT as a part of PET/CT, colonic wall thickening and pericolic fat stranding may be seen in association with diffuse or segmental increased 18 F-FDG uptake. 18 F-FDG PET/CT imaging was reported to be more sensitive than CT in the early detection of colitis as a result of ICI treatment (6,17,18). However, 18 F-FDG PET has a low specificity for colitis due to physiologic mucosal, muscular, and luminal activity.…”

Current Immunotherapy Approaches in Non-Hodgkin Lymphomas

“…As there are no established diagnostic tests, diagnosis is usually made by exclusion of other possible causes of organ involvement. Comprehensive guidelines for organ toxicity management associated with checkpoint inhibitor therapy are available [ 205 , 206 ]. In general, immune checkpoint inhibitors may be continued in most cases of grade 1 organ toxicities, except for some neurologic, hematologic and cardiac side-effects.…”