Introduction and Context
Immune checkpoint inhibitors (ICIs) — drugs that unleash T-cell responses against tumors — have transformed outcomes across many cancers. Yet their immune-activating mechanism also produces immune-related adverse events (irAEs). Among those, cardiovascular (CV) toxic effects have emerged as a high-stakes problem because they can be sudden, severe, and sometimes fatal. The International Cardio-Oncology Society (ICOS) convened cardiologists, oncologists, hematologists, and allied specialists to issue a comprehensive position statement on ICI-associated cardiovascular toxic effects, published in JAMA Oncology (Herrmann et al., 2025). This statement synthesizes recent evidence and expert consensus to guide diagnosis, grading, treatment, monitoring, and decisions about continuing or rechallenging ICI therapy.
The ICOS document matters now because: 1) ICIs are used in more indications and in combination regimens, increasing exposure; 2) clinical recognition has broadened beyond fulminant myocarditis to a spectrum that includes subclinical troponin elevations, pericardial disease, arrhythmias, and accelerated atherosclerotic events; and 3) emerging immunomodulatory strategies (e.g., abatacept) offer new treatment options but lack randomized evidence.
