Clinical Outcomes and Safety of Anakinra in the Treatment of Multisystem Inflammatory Syndrome in Children: a Single Center Prospective Observational Study

Abstract Background and objective: Evidence for the treatment of multisystem inflammatory syndrome in children (MIS-C) is lacking. Anakinra, which targets IL-1-mediated inflammation, is reserved for refractory cases of MIS-C; however, its use in the treatment of MIS-C is not clearly established. Patients and Methods: To examine a role for anakinra in MIS-C, we performed a single center prospective observational cohort study of all MIS-C patients diagnosed at our children’s hospital from May 15 to November 15, 2020. Demographics, clinical features, diagnostic testing, and cardiac function parameters were compared between MIS-C patients treated with intravenous immunoglobulin (IVIG) monotherapy and IVIG with anakinra (IVIG+anakinra). Results: Among 46 patients with confirmed MIS-C, 32 (70%) were in the IVIG+anakinra group, of which 9 of these patients (28%) were also given corticosteroids (CS). No patients were treated with anakinra alone. MIS-C patients in the IVIG+anakinra group were enriched in a CV shock phenotype (p=0.02), and those with CV shock were treated with higher doses of anakinra for a longer duration. Furthermore, MIS-C patients in the IVIG+anakinra group exhibited improvements in fever and cardiac function with and without CS. No significant adverse events were observed, and no differences in IL-1β levels were found among MIS-C patients in the IVIG+anakinra group. Conclusions: Anakinra treatment, which was co-administered with IVIG and primarily in patients with severe MIS-C, was associated with improvements in fever and cardiac function, and demonstrated a favorable side-effect profile. These findings suggest a role for adjunctive anakinra in the treatment of MIS-C.