Bortezomib is efficacious in the treatment of severe childhood-onset neuropsychiatric systemic lupus erythematosus with psychosis: a case series and mini-review of B-cell immunomodulation in antibody-mediated diseases.

Childhood-onset neuropsychiatric systemic lupus erythematosus (cNPSLE) with psychosis is a challenging manifestation of SLE. Pathogenic long-lived plasma cells (LLPCs) are not specifically targeted by standard immunosuppression and their persistence contributes to chronic autoimmunity. Bortezomib is approved for the treatment of multiple myeloma and has shown benefits in a variety of other antibody-mediated diseases. Bortezomib may be efficacious for severe or treatment-refractory cNPSLE through eradication of LLPCs, decreasing autoantibody production. We describe the first pediatric case series of five patients with unrelenting cNPSLE with psychosis who were treated safely and effectively with bortezomib between 2011 and 2017. Most patients had persistent cNPSLE with psychosis despite aggressive immunosuppression with methylprednisolone, cyclophosphamide, rituximab, and usually plasmapheresis. All patients demonstrated rapid clinical improvement in their psychotic manifestations with the ability to quickly taper immunosuppression after the introduction of bortezomib. No patient had a recurrence of overt psychosis during a follow-up period of 1-10 years. Secondary hypogammaglobulinemia developed in all five patients and required immunoglobulin replacement. No other severe side effects or adverse events were observed. Bortezomib-mediated LLPC depletion is a promising therapy for severe recalcitrant cNPSLE with psychosis when used as adjunctive therapy to conventional immunosuppression, B-cell, and antibody-depleting therapies. After initiation of bortezomib, patients had rapid, demonstrable improvement in psychosis as well as reduction in glucocorticoids and antipsychotics. Further investigation is needed to determine the therapeutic role of bortezomib in severe cNPSLE and cSLE. We present a mini-review of the rationale for bortezomib use and novel B-cell immunomodulation in rheumatic disease.