Early treatment with rituximab may be associated with improved outcomes in patients with new-onset generalised myasthenia gravis (MG), according to a study published in JAMA Neurology.
The Swedish study of 72 patients, identified through the country’s MG registry, suggests the B-cell–depleting monoclonal antibody might be more effective than conventional immunosuppressants and could be used earlier than in the refractory disease setting.
The study included patients treated with at least one dose of rituximab of variable doses and excluded patients with muscle-specific tyrosine kinase (MuSK+) antibodies. The mean baseline Quantitative Myasthenia Gravis (QMG) score ranged from 6-8.
Almost half the patients (47.2%) had refractory disease and had started rituximab after previous exposure to at least one other conventional immunosuppressant and one third of patients (33%) had new onset disease and started rituximab within months of diagnosis. A further 19% of patients had untreated MG for more than 12 months before starting rituximab.
A control cohort included 26 patients with new onset disease on conventional immunosuppressants.
The study found 76% of patients fulfilled criteria for remission during the study period – with time to remission shorter in the new-onset group compared with therapy-refractory patients (7 vs 16 months; HR 2.53).
Patients in the new onset disease group receiving rituximab also achieved remission faster than the control group on conventional immunosuppressants (7 v 11 months; HR 2.97).
“Furthermore, in a post hoc analysis, the proportions of patients in clinical remission at 12 and 24 months were larger with rituximab than conventional immunotherapies (12 months: 20/23 [87%] rituximab-treated vs 15/26 [58%] controls; OR, 14.04; 95% CI, 1.82-108.59; P = .01 after adjustment and 24 months: 22/23 [96%] rituximab-treated vs 16/26 [62%] controls; OR, 21.34; 95% CI, 1.14-401.12; P = .004 after adjustment).”
In addition, rituximab-treated patients required fewer rescue therapies during the first 24 months of observation compared with the control group (0.38 v 1.31).
Rituximab-treated patients had more sustained remission, were tapered off immunomodulatory drugs faster and had lower rates of drug discontinuation due to adverse events than other patients.
“The two main findings of this study are that treatment outcomes were more favourable with rituximab started early after disease onset of non-MuSK+ gMG, and rituximab in this patient group performed better than conventional immunosuppressants,” the study authors said.
“Together, these findings suggest consideration for placing rituximab earlier in the treatment algorithm because it is now considered a possible third-line option.”
They noted however that conclusions about the clinical effectiveness of rituximab in new-onset gMG must wait for results from an ongoing randomised clinical trial which are expected in 2021.