Monoclonal antibodies targeting IL-5/5R or IL-4/13 pathways in eosinophilic myocarditis: a single-center experience and systematic literature review

AIMS: Eosinophilic myocarditis (EM) is a rare inflammatory heart disease often associated with eosinophilic granulomatosis with polyangiitis or hypereosinophilic syndrome. While anti-IL-5/5R and anti-IL-4/13 monoclonal antibodies (mAbs) efficacy in systemic eosinophilic diseases is established, data on EM are lacking. We aimed to: (1) characterize a single-center cohort of EM patients treated with mepolizumab, benralizumab, or dupilumab in combination with glucocorticoids and/or immunosuppressants; (2) systematically review published cases, comparing them with a contemporary cohort; (3) evaluate myocardial response and safety of mAbs in EM, in comparison with a historical cohort treated without mAbs at our center. METHODS AND RESULTS: Thirty-seven EM patients were included (19 from a contemporary cohort, 18 from the literature; 51% male; median age 47 years). Biologic treatments were mepolizumab (81%), benralizumab (14%), and dupilumab (5%). Median time to mAb initiation was 2.5 months; treatment duration 24 months. No EM relapses, deaths, or heart transplantations occurred. Glucocorticoids were tapered and withdrawn in 89% of cases, with no mAb discontinuations due to adverse events. In the contemporary cohort, mAb therapy was associated with improved LVEF (47% to 55%, p = 0.004), TnI normalization (95% to 12%, p < 0.001), and eosinophil reduction (95% to 11%, p < 0.001). Compared to EM patients managed with conventional immunosuppressants alone, the mAb group had no myocarditis relapses (0% vs. 25%) and lower follow-up eosinophil counts (0.04 ×109/L vs 0.85 ×109/L). CONCLUSION: In EM within eosinophilic disease, anti-IL-5/5R and anti-IL-4/13 mAbs showed steroid-sparing effects and favorable safety, suggesting potential benefit for disease control.