Satralizumab as an add-on treatment in refractory pediatric AQP4-antibody-positive neuromyelitis optica spectrum disorder: a case report

Abstract

Neuromyelitis optica spectrum disorder (NMOSD) is a rare autoimmune disease of the central nervous system. Relapse and incomplete recovery from relapse are common in NMOSD. Most patients with NMOSD have IgG to aquaporin-4 (AQP4-IgG). New biological agents for AQP4-IgG-seropositive NMOSD, such as satralizumab, have become available for maintenance therapy. Satralizumab is an anti-interleukin-6 receptor monoclonal antibody. To date, few studies have evaluated satralizumab as an add-on treatment in pediatric NMOSD patients. Here, we report an 11-year-old girl with NMOSD who frequently relapsed under long-term treatment, including oral prednisone, rituximab, mycophenolate mofetil (MMF), and maintenance intravenous immunoglobulin treatment even with B-cell depletion. For the poor treatment response and to improve the efficacy of relapse prevention further, the patient received satralizumab treatment as an add-on therapy to MMF plus oral prednisone, with a dose of 120 mg administered subcutaneously at weeks 0, 2, and 4 and every 4 weeks after that. After initiating satralizumab, the patient remained relapse-free for 14 months at the last follow-up. Satralizumab might be effective and safe as an add-on treatment in refractory pediatric AQP4-IgG-seropositive NMOSD under B-cell depletion.

Keywords: AQP4; NMOSD; pediatric; relapse; satralizumab.

Figure 1

Timeline depicting visual acuity change, immunotherapy, and serum AQP4 IgG. VA, visual acuity; AQP4, aquaporin-4; IA, immunoadsorption; IVIG, intravenous immunoglobulin; IVMP, intravenous methylprednisolone; MMF, mycophenolate mofetil; RTX, rituximab.

Figure 2

MRI at onset and follow-up. Axial cranial T2-weighted images showing T2-hyperintense lesions in pons (A), midbrain (B), posterior limb of internal capsule (C), and subcortical white matter of the frontal and parietal lobe (D). Axial orbital T2-weighted image showing longitudinally extensive T2-hyperintense lesions in the bilateral optic nerve (E) with gadolinium enhancement in the T1-weighted gadolinium-enhanced image (F). Axial cranial T2-weighted images showing new T2-hyperintense lesions in subcortical and deep white matter of the frontal, parietal, and occipital lobes after treatment with IVMP and IVIG at onset attack (G). Axial orbital T2-weighted image showing that lesions in the left optic nerve disappeared, whereas in the right optic nerve they became smaller without gadolinium enhancement in T1-weighted gadolinium-enhanced image at follow-up after immunosorbent therapy (H, I). Sagittal spinal T2 weighted image showing T2-hyperintense lesions at onset (J) and resolution of lesions at follow-up after immunosorbent therapy (K).

Figure 3

MRI at relapse and follow-up. Axial orbital T2-weighted image showing lesions in bilateral optic nerve with gadolinium enhancement in the T1-weighted gadolinium-enhanced image at relapse in April 2021 (A, B). Axial orbital T2-weighted image showing lesions in the left optic nerve with gadolinium enhancement in the T1-weighted gadolinium-enhanced image at relapse in December 2021 (C, D). Axial orbital T2-weighted image showing that lesions disappeared in the bilateral optic nerve at the last follow-up in April 2023 (E, F).