Blinatumomab in dermatomyositis and refractory ANCA-associated vasculitis: a 2-patient exploratory study

This study aims to explore the safety and efficacy of blinatumomab for the treatment of autoimmune diseases.

Two patients, 1 with dermatomyositis (DM) and 1 with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), were treated with blinatumomab (CD19 × CD3 bispecific T-cell engager antibody) administered by continuous intravenous infusion for 2 cycles. Evaluations were conducted every 2 weeks until week 12, and then once every 4 weeks during continued follow-up through week 24, as well as on week 56. Immune cell dynamics were assessed by flow cytometry and single-cell RNA sequencing.

During the 14-month follow-up, we observed rapid T-cell activation and B-cell depletion in peripheral blood, together with clinical improvement in both patients, without cytokine release syndrome or other serious adverse events. Moreover, 12 weeks after treatment, both T cells and B cells returned towards a state of homeostasis, accompanied by reduced B-cell activation and downregulation of proinflammatory genes in myeloid compartments. Low-dose blinatumomab treatment was followed by sustained clinical improvement over the 14-month follow-up period, together with marked peripheral B-cell depletion and an acceptable safety and tolerability profile.

This study provides longitudinal clinical and immunological observations of blinatumomab treatment in anti-Mi-2-positive DM and refractory AAV. These exploratory findings support further evaluation of blinatumomab in autoimmune diseases.