CD19xCD3 T cell engager blinatumomab effective in refractory generalized myasthenic syndromes.

In this case series, we report the first off-label use of the CD19xCD3 T cell engager blinatumomab in two patients with generalized myasthenia gravis (MG). Refractory MG remains a major therapeutic challenge, with patients experiencing severe disability and potentially life-threatening crises despite intensive immunotherapy. This study evaluates the clinical efficacy and safety of short-term blinatumomab treatment in two patients with severe, refractory generalized MG. Both individuals had been experiencing persistent disease burden with myasthenic crises leading to severe disability, despite multimodal immunotherapy. Following treatment with blinatumomab, both patients showed rapid and sustained clinical improvements, reflected in significant reductions in MG-specific scores (MG Activities of Daily Living scale, Quantitative MG score, and revised MG Quality of Life-15), further patient-reported outcomes, digital activity markers, and gait analyses. Laboratory findings revealed persistent B cell depletion in patient 1, whereas patient 2 demonstrated clinical improvement and autoantibody reduction despite B cell repopulation by day 106. Both patients experienced grade 1 cytokine release syndrome during initial treatment phases, but no neurotoxicity or severe adverse events were observed. This report underscores the potential of CD19xCD3 T cell engagers as a promising therapeutic approach in severe autoimmune neuroimmunological disorders, warranting further investigation in clinical trials and mechanistic studies.