Background

People with antibodies to myelin oligodendrocyte glycoprotein (MOG) using reliable cell-based assays have heterogeneous course. Best management practices and outcome predictors are still uncertain.

Objectives

This study aimed to assess the treatment experience in a relapsing MOG positive cohort and the impact on disability accrual.

Methods

Retrospective chart review of (aquaporin4 negative) MOG antibody positive patients at University of British Columbia Multiple Sclerosis Clinic with relapsing disease, and minimum 1year follow-up.

Results

Of 49 MOG positive patients, 37(64.8% female) met inclusion criteria. Median age was 26 years (range 3-62; 10 pediatric cases) with median follow-up of 6years(range 1-36). Median time to second disease episode from first was 12 months (range 1-228); and to third (n=27) was 25 months (range 3-312). Median number total disease episodes was 3 (range 2-10).

For some, management decisions were initiated prior to MOG diagnosis. At first disease presentation 35/37 patients received acute therapy but only 1 started chronic therapy. First-line chronic therapies were later started in another 30 patients; in 35%(13/37) after second disease episode, and at the third in 27%(10/37). Most common were azathioprine(61%) and rituximab(19%). Sixteen patients(52%) required second line therapy, mostly due to adverse effects(62.5%) or disease activity(31%). Most common second line therapies were mycophenolate mofetil (MMF) or rituximab. Three patients required third line therapy.

17/37 patients had good outcome (EDSS<2) at last follow-up despite relapsing course, whilst 20(54%) had residual disability. Onset clinical phenotype distribution was similar between these two outcomes. 5% had persistent disability from disease onset, but mostly this developed from the second(19%) or third(16%) episode. 4/6 untreated patients had good outcome. Only 30% of the pediatric cohort vs 63% of the adult cohort had EDSS ≥2.0.

Conclusions

Chronic therapy was not typically started at disease onset, mostly due to initial absence of diagnosis. Azathioprine, MMF and rituximab were all effective therapies. Azathioprine was associated with high proportion of intolerance. Approximately half of patients recovered well from the initial episode; the rest accrued disability, typically from second or third disease episode, independent of clinical phenotype at onset. Further studies are required to identify factors influencing disability accrual, to enable earlier effective treatment in those at highest risk.