Immune Biomarker Predicts Risk of Heart Damage from Cancer Drugs

Recent research has identified immune system changes in cancer patients that could serve as predictive markers for heart-related side effects caused by immune checkpoint inhibitors. These groundbreaking findings suggest that measuring specific immune biomarkers before starting treatment could help identify patients at higher risk of cardiovascular complications, such as myocarditis, a serious and potentially fatal inflammation of the heart muscle.

The study, led by Assistant Professor Pilar Martín from the Spanish National Center for Cardiovascular Research (CNIC), focused on immune cell level alterations in patients undergoing cancer therapy with immune checkpoint inhibitors. These drugs, which boost the body's immune response against tumors, have been revolutionary in cancer treatment. However, they can also unintendedly damage the heart in some patients.

Martín explained that a notable early change observed was the rapid decline in regulatory T cells—immune cells that normally protect the heart from immune-mediated damage—after treatment initiation. This sudden decrease creates a vulnerable window during which the heart is more susceptible to inflammation and injury.

Researchers analyzed blood samples from 215 cancer patients with various types of cancer, including lung, breast, and skin cancers, prior to and over the course of treatment spanning up to a year. They discovered that patients with lower levels of a specific biomarker called CD69—found in protective immune cells—experienced more significant reductions in these cells and a corresponding increase in pro-inflammatory immune cells. This imbalance has been associated with a higher likelihood of developing cardiovascular problems.

Using these insights, patients were categorized based on their initial CD69 levels. Those with lower baseline levels showed a greater immune response decline and a heightened risk of heart damage. This indicates that simple blood tests measuring CD69 could enable healthcare providers to pinpoint high-risk patients early, allowing for closer monitoring or preventive interventions.

While further validation is needed, this research highlights the potential of immune biomarkers to personalize cancer treatment and reduce adverse effects. Monitoring immune cell levels could become an essential aspect of managing patients on immune checkpoint inhibitors, ultimately safeguarding heart health while fighting cancer.

This study was presented at the European Cardio-Oncology 2025 congress of the European Society of Cardiology, emphasizing the importance of integrating cardiology and oncology to improve patient outcomes.