Inflammatory and Infectious Syndromes Associated With Cancer Immunotherapies

Immunotherapy using antibodies to immune checkpoint molecules or targeted chimeric antigen receptor-modified T cells (CAR-T cells) represent dramatic advances in cancer treatment. These therapies mediate immune-related adverse events that may mimic or amplify infectious presentations. Checkpoint inhibitor therapy may be associated with diverse irAEs including mild skin, endocrine, and autoimmune manifestations or severe inflammatory processes including colitis, pneumonitis, myocarditis, and shock. CAR-T-cell therapies may induce toxicities including cytokine-release syndrome with fevers and multiorgan dysfunction, CAR-T-cell-related encephalopathy syndrome with altered mental status and neurologic dysfunction, or hemophagocytic lymphohistiocytosis-macrophage-activation syndrome. Infectious risks may relate to prior cancer therapies or to treatments of inflammatory dysregulation, including corticosteroids and inhibitors of tumor necrosis factor-α and interleukin-6. Immune activation may unmask subclinical infections. Clinical approaches must attempt to identify infections in the face of immunotherapy-associated inflammatory processes. Empirical antimicrobial therapies should not be delayed based on the presumption of noninfectious syndromes.