Neuromuscular and cardiac adverse events associated with immune checkpoint inhibitors: pooled analysis of individual cases from multiple institutions and literature

Background: Immune checkpoint inhibitors (ICIs) have revolutionized the management of multiple tumors, due to improved efficacy, quality of life, and safety. While most immune-related adverse events (irAEs) are mild and easily managed, in rare cases such events may be life-threatening, especially those affecting the neuromuscular and cardiac system. The management of neuromuscular/cardiac irAEs is not clear due to the lack of consistent data. Therefore, we carried out a pooled analysis of collected cases from selected Italian centers and individual data from published case reports and case series, in order to improve our understanding of these irAEs. Patients and methods: We collected retrospective data from patients treated in six Italian centers with ICIs (programmed cell death protein 1 or programmed death-ligand 1 and/or cytotoxic T-lymphocyte antigen 4 inhibitor) for any solid tumor who experienced neuromuscular and/or cardiovascular toxicity. Then, we carried out a search of case reports and series of neuromuscular/cardiac irAEs from ICIs with any solid tumor. Results: This analysis includes cases from Italian institutions (n = 18) and the case reports identified in our systematic literature search (n = 120), for a total of 138 patients. Among these patients, 50 (36.2%) had complete resolution of their neuromuscular/cardiac irAEs, in 21 (15.2%) cases there was a clinical improvement with mild sequelae, and 53 (38.4%) patients died as a result of the irAEs. Factors significantly associated with worse outcomes were early irAE onset, within the first two cycles of ICI (Fisher P < 0.0001), clinical manifestation of both myositis and myocarditis when compared with patients who developed only myositis or myocarditis (chi-square P = 0.0045), and the development of arrhythmia (Fisher P = 0.0070). Conclusions: To the best of our knowledge, this is the largest collection of individual cases of immune-related myocarditis/myositis. Early irAE onset, concurrent development of myositis and myocarditis, as well as occurrence of arrhythmias are associated with worse outcomes and should encourage an aggressive immunomodulatory treatment.