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-centre 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; and (3) evaluate myocardial response and safety of mAbs in EM, in comparison with a historical cohort treated without mAbs at our centre. 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 Glucocorticoids were tapered and withdrawn in 89% of cases, with no mAb discontinuations due to adverse events.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%-55%, P = 0.004), TnI normalization (95%-12%, P < 0.001), and eosinophil reduction (95%-11%, P < 0.001). Compared with 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 favourable safety, suggesting potential benefit for disease control.