Abstract 4144219: Safety and Efficacy of Rechallenging Immune Checkpoint Inhibitors After Discontinuation Due to Immune-Associated Myocarditis in Cancer Patients

Background: Immune checkpoint inhibitor-associated myocarditis (ICIAM), a highly fatal immune-related adverse event (irAE) in cancer patients receiving immune checkpoint blockade (ICB) therapy, necessitates immediate termination of ICB once diagnosed. Research Questions: However, no studies have yet explored how to safely and effectively rechallenge ICB for long-term tumor control. Aims: To investigate the clinical course, treatment, and prognosis of patients with ICIAM undergoing ICB rechallenge (ICBR). Methods: This study retrospectively evaluated consecutive patients admitted to Zhongshan Hospital with clinically diagnosed ICIAM according to the 2022 European Society of Cardiology (ESC) guidelines from January 2020 to April 2022. Clinical, biological, imaging, treatment, and prognostic data were collected. Patients were grouped based on the recurrence of irAE following ICBR. Results: A total of 23 ICIAM patients (64.39 ± 9.40 years) who underwent ICBR were included. According to the Common Terminology Criteria for Adverse Events (CTCAE), myocarditis grades were: 11 patients (47.83%) with grade 1, 5 patients (21.74%) with grade 2, and 7 patients (30.43%) with grade 3. The median initial cardiac troponin T (cTnT) was 0.072 ng/ml (IQR, 0.037-0.096). Fourteen patients (60.87%) were administered glucocorticosteroids (GC). Twelve patients (52.17%) reported a recurrence of irAE following ICBR, including elevated cTnT (58.33%), pneumonia (16.67%), enteritis (8.33%), thyroiditis (8.33%), hypocortisolism (8.33%), and hemophagocytic syndrome (8.33%). A higher proportion of patients who developed irAEs following ICBR were administered GC (75% vs. 45.45%, p<0.001). The median progression-free survival (mPFS) was 8.5 months (95% CI: 6, NA) after ICBR. Conclusions: Rechallenging immunotherapy for patients with ICIAM was relatively safe and controllable, despite the potential recurrence of non-fatal irAEs. Additionally, patients often achieved better tumor control after ICBR, indicating that ICBR can be a viable option for maintaining long-term tumor management.