An Australian study provides additional support for the use of the B-cell depleting therapy rituximab as a first line treatment of neuromyelitis optica spectrum disorder (NMOSD).
The retrospective, unblinded observational study comprised 75 patients who met the International Panel for NMO Diagnosis (IPND) criteria for NMOSD. Of these, 68 were AQP4 antibody positive and complete relapse and treatment data was available for 43 patients.
Sixteen patients were treated with rituximab and 27 with other therapies including traditional immunosuppressive therapies of azathioprine, cyclophosphamide, methotrexate, and mycophenolate, or β-interferon.
The study, published in Multiple Sclerosis and Related Disorders, found treatment with rituximab was associated with a 35% reduction in the annualised relapse rate (ARR) compared to pre-treatment, although this was not statistically significant.
“The other therapies analysed showed no significant reductions in ARR before and after commencing therapy,” the study said.
“Time to event analysis suggested a benefit for rituximab compared with no treatment, beta-interferon and traditional immunosuppressive therapy, but these differences were not statistically significant.”
All three treatments increased time to first relapse, but the benefit was most marked for rituximab (median time to first relapse = 29.4 months versus 11.5 for no treatment, p= 0.0051).
Disability outcomes as assessed by EDSS were significantly better for patients treated with immunosuppressive therapy and rituximab when compared to β-interferon.
“The data presented suggest a beneficial effect of rituximab in terms of change in pre- and post-treatment ARR, time to first relapse and final disability level,” the study said.
“Of the four traditional immunosuppressive therapies used in this cohort, cyclophosphamide was least beneficial and may have been associated with an increased risk of relapse. Outcomes for β-interferon for both ARR and EDSS were not as good as traditional immunosuppressive therapies and rituximab, and a trend towards increased ARR was seen on treatment.”
The investigators, from the ANZ NMO Collaboration, said their findings were consistent with increasing evidence that anti-B cell therapy has a therapeutic effect in NMOSD.
They said it suggests that dysregulation of early B cell tolerance was integral to the pathogenesis of NMOSD and that B cell therapy should be considered as first line therapy.