Autologous Hematopoietic Stem Cell Transplantation In Neuromyelitis Optica: A Retrospective Study Of The EBMT Autoimmune Diseases Working Party In Collaboration With The University Of Sao Paulo, Ribeirao Preto, Brazil

Neuromyelitis optica (NMO) is an inflammatory and demyelinating disorder of the central nervous system. Recently NMO has been recognized as an autoimmune astrocytopathy, distinct from multiple sclerosis and hallmarked by pathogenic anti-aquaporin 4 (AQP4) antibodies (Kim et al, Mult Scler, 2013). Currently NMO carries a poorer prognosis than multiple sclerosis (MS) and its response to various immunosuppressive treatments remains largely unsatisfactory. Use of Autologous stem cell transplantation (ASCT) has been reported worldwide as a tool for inducing prolonged restoration of self-tolerance in MS and other severe autoimmune diseases (AD), refractory to conventional treatments. In this context, NMO treatment resistant cases were considered for ASCT on a ‘Clinical Option’ basis, according to EBMT guidelines (Snowden et al, Bone Marrow Transplant, 2012). Only 2 isolated NMO cases with contradictory results (Matiello et al, Arch Neurol, 2011; Peng et al, Neurologist, 2010) and a Chinese report of 21 opticospinal multiple sclerosis patients treated by ASCT (Xu et al, Ann Hematol, 2011) are reported in the literature. Therefore, the EBMT Autoimmune Diseases Working Party (ADWP) conducted a survey to address NMO disease response following ASCT.

This retrospective study followed the EBMT study guidelines. All centers were invited to participate. Sixteen patients with aggressive forms of NMO refractory to standard treatments treated by ASCT between 2001 and 2011 had been reported to the EBMT registry. For each case, a specific questionnaire was sent to complete information by referring haematologist and neurologist about NMO, ASCT and outcome including disease response, relapse and progression. Results are reported as median.

Patients (13 females and 3 males) had a median age of 37 years at transplant. Previous treatments had included high-dose steroids (12/16), immunoglobulins (5/16), iv cyclophosphamide (Cy, in 8/16), rituximab (5/16), mitoxantrone (2/16), plasma exchanges (8/16), azathioprine (5/16) and methotrexate (1/16). Median time between NMO diagnosis and transplant was 24 months. Before ASCT, the median EDSS (the Kurtzke Expanded Disability Status Scale) was of 6.5, 10/16 patients were positive for AQP4 antibodies and 11/16 had active lesions on magnetic resonance imaging (MRI). Peripheral blood stem cells mobilization, high-dose alkylating agent such as Cy (14/16) or monoclonal antibodies as Rituximab (2/16), followed by granulocyte colony stimulating factor (G-CSF), was successfully achieved in all cases (16/16). The conditioning regimen consisted of BEAM plus anti-thymocyte globulin (9/16) or Thiotepa-Cy (3/16) or Cy and anti-thymocyte globulin (4/16). Hematopoietic recovery was documented in all patients within 10 days (range 3-25) after ASCT, both for neutrophils and platelets, with a median number of 4 red blood cells and 5 platelet units transfusions. Infectious complications required specific treatment in 9 patients (6 febrile neutropenia, 5 CMV and 2 VZV reactivations, 1 aspergillosis). All patients responded initially. Relapse, necessitating further treatments, occurred in 13/16 at a median of 7 months after ASCT, presenting a median EDSS of 7 (range 3-8.5) and a worsening of MRI (11 cases). NMO progression was observed in 9/16 patients at a median of 10 months after ASCT. In the eight patients evaluable for AQP4 antibodies in the follow-up phase, the pathogenic autoantibodies remained positive after ASCT. Disease-free survival at 3 and 5 years were 31% and 10%, respectively, while progression-free survival at 3 and 5 years were 48%. No secondary malignancy was documented. All patients, but one patient who died from disease progression, are alive at a median follow up of 47 months after ASCT.

This EBMT retrospective study further demonstrates the potential of ASCT to reduce the highly inflammatory picture typical of NMO, at least in the short term, together with a low incidence of toxicities. Despite transient response after ASCT in the majority of cases, NMO relapsed at later time points underlying the need to investigate maintenance strategies to improve disease outcome in the long term after ASCT.

No relevant conflicts of interest to declare.