Autologous nonmyeloablative hematopoietic stem cell transplantation for neuromyelitis optica

Abstract

Objective: To determine if autologous nonmyeloablative hematopoietic stem cell transplantation (HSCT) could be a salvage therapy for neuromyelitis optica spectrum disorder (NMOSD).

Methods: Thirteen patients were enrolled in a prospective open-label cohort study (11 NMOSD aquaporin-4-immunoglobulin G [AQP4-IgG]-positive, 1 NMOSD without AQP4, and 1 NMOSD AQP4-IgG-positive with neuropsychiatric systemic lupus erythematosus [SLE]). Following stem cell mobilization with cyclophosphamide (2 g/m2) and filgrastim, patients were treated with cyclophosphamide (200 mg/kg) divided as 50 mg/kg IV on day -5 to day -2, rATG (thymoglobulin) given IV at 0.5 mg/kg on day -5, 1 mg/kg on day -4, and 1.5 mg/kg on days -3, -2, and -1 (total dose 6 mg/kg), and rituximab 500 mg IV on days -6 and +1. Unselected peripheral blood stem cells were infused on day 0. AQP4-IgG antibody status was determined by Clinical Laboratory Improvement Amendments-validated ELISA or flow cytometry assays. Cell-killing activity was measured using a flow cytometry-based complement assay.

Results: Median follow-up was 57 months. The patient with coexistent SLE died of complications of active lupus 10 months after HSCT. For the 12 patients with NMOSD without other active coexisting autoimmune diseases, 11 patients are more than 5 years post-transplant, and 80% are relapse-free off all immunosuppression (p < 0.001). At 1 and 5 years after HSCT, Expanded Disability Status Scale score improved from a baseline mean of 4.4 to 3.3 (p < 0.01) at 5 years. The Neurologic Rating Scale score improved after HSCT from a baseline mean of 69.5 to 85.7 at 5 years (p < 0.01). The Short Form-36 health survey for quality of life total score improved from mean 34.2 to 62.1 (p = 0.001) at 5 years. In the 11 patients whose baseline AQP4-IgG serostatus was positive, 9 patients became seronegative by the immunofluorescence or cell-binding assays available at the time; complement activating and cell-killing ability of patient serum was switched off in 6 of 7 patients with before and after HSCT testing. Two patients remained AQP4-IgG-seropositive (with persistent complement activating and cell-killing ability) and relapsed within 2 years of HSCT. No patient with seronegative conversion relapsed.

Conclusion: Prolonged drug-free remission with AQP4-IgG seroconversion to negative following nonmyeloablative autologous HSCT warrants further investigation.

© 2019 American Academy of Neurology.

Figures

Figure 1. Neurologic outcome after hematopoietic stem cell transplantation (HSCT) for neuromyelitis optica spectrum disorder

(A–D) EDSS = Expanded Disability Status Scale (range 0–10 in 0.5 increments from none [0] to worst [10] neurologic disability). NRS = neurologic rating scale (range 0 [worse]–100 [best] in 1-point increments).

Figure 2. Device assistance for ambulation before and after hematopoietic stem cell transplantation (HSCT)

The number of patients who required no assistance for ambulation went from 6 of 12 pre-HSCT to 9, 10, 9, 8, 8, and 9 at 6 months, 1, 2, 3, 4, and 5 years post transplantation, respectively. AFO = ankle and foot orthoses.

Figure 3. Aquaporin-4 (AQP4) titer by AQP4 flow cytometry assay (fluorescence-activated cell sorting [FACS]) pre and post hematopoietic stem cell transplantation (HSCT) from stored serum samples

The color lines represent AQP4–immunoglobulin G (IgG) titers of each patient by FACS assay on stored serum samples. Patients 4 and 8 relapsed after transplantation. Patient 5 was negative pre and post HSCT for both AQP4-IgG index and complement.

Figure 4. Complement activation titers from pre and post hematopoietic stem cell transplantation (HSCT) stored serum samples

The color lines represent aquaporin-4 (AQP4)–immunoglobulin G (IgG) complement activation titers of each patient by fluorescence-activated cell sorting assay on stored serum samples. Patients 4 and 8 relapsed after transplantation. Patient 5 was negative pre and post HSCT for both AQP4-IgG index and complement.