Breaking the storm: canakinumab as salvage therapy for refractory macrophage activation syndrome in pediatric systemic lupus erythematosus-a case report.

BACKGROUND

Macrophage activation syndrome (MAS) complicating pediatric systemic lupus erythematosus (cSLE) is a life-threatening hyperinflammatory state driven by dysregulated cytokine release. A recent systematic literature review identified only a limited number of cSLE-MAS cases treated with IL-1 inhibitors, with variable efficacy, underscoring the need for evidence-based salvage strategies when first-line biologic therapy fails. We report a 17-year-old female with cSLE who developed secondary hemophagocytic lymphohistiocytosis/MAS fulfilling HLH-2004 criteria approximately 17 months after initial diagnosis, in the setting of medication nonadherence and nutritional failure. The MAS course was refractory to intravenous immunoglobulin, pulse methylprednisolone, dexamethasone, cyclosporine, and intravenous anakinra, and was further complicated by a secondary Clostridioides difficile superinfection precipitating a MAS flare with ferritin peaking at > 10,000 ng/mL. Following transfer to our institution, subcutaneous canakinumab at standard weight-based dosing produced prompt defervescence, sustained ferritin normalization, and clinical stabilization permitting transition to outpatient immunomodulation.

CONCLUSIONS

This case highlights canakinumab as a viable salvage therapeutic option for patients with biologic-refractory cSLE-MAS. Emerging evidence supports an expanding role for selective IL-1β blockade in pediatric lupus-associated hyperinflammatory syndromes; prospective studies are needed to define optimal dosing, sequencing, and treatment duration.