High-dose immunosuppressive therapy followed by haematopoietic stem cell transplantation as a method for the treatment of refractory forms of neuromyelitis optica spectrum disorder in children

Neuromyelitis optica spectrum disorders (NMOSD) is a general term for immune-mediated diseases of the central nervous system whose phenotype includes affection of the optic nerve, brainstem encephalitis and myelitis. NMOSD is most commonly associated with class G antibodies against aquaporin-4 (aquaporin-4 immunoglobulin G, AQP4-IgG), less commonly with class G antibodies against the glycoprotein of myelin oligodendrocytes. There are also seronegative variants of NMOSD. The article describes our own experience in treating two boys with resistant NMOSD with AQP4-IgG positivity with high-dose immunosuppressive therapy (HIST) followed by haematopoietic stem cell transplantation (HSCT). In the first clinical observation, a case of resistant NMOSD in a 13-year-old boy is presented. Over the course of 6 months, the child’s neurological deficit progressed to 9.5 points on the Expanded Disability Status Scale (EDSS). After mobilization of peripheral stem cells (PSC), HIST was performed, followed by autologous HSCT (autoHSCT). During the 18-month follow-up, no NMOSD activity and the decrease in EDSS to 7.0 points were maintained. In the second clinical observation, the experience with the treatment of a child with resistant high-activity NMOSD is presented. A 10-year-old boy had two exacerbations within four months against the background of two lines of immunosuppressive therapy. PSCs were collected before auto-HSCT, but due to a further exacerbation and lack of clinical response to the mobilization dose of cyclophosphamide, it was decided to perform an allogeneic HSCT from a haploidentical donor. The follow-up period was 9 months. The EDSS score decreased from 6.5 to 3.5. AQP4-IgG was not detected in the blood of either patient. Both patients received satralizumab as part of consolidation therapy. No significant complications were observed after transplantation. Thus, HIST followed by HSCT can be considered a promising method for the treatment of resistant forms of NMOSD. The choice of HSCT type may depend on the severity of the patient’s somatic and neurological condition as well as the clinical response to immunosuppressive therapy.