CD19 and CD20 B-Cell Depletion in MG

This episode, titled ‘CD19 and CD20 B-Cell Depletion in MG,’ features panelists examining clinical evidence for inebilizumab and rituximab and the implications of targeting different B-cell populations. The discussion begins with the phase 3 MINT study of CD19-directed therapy with inebilizumab. Expert faculty highlight the inclusion of both acetylcholine receptor antibody–positive and MuSK-positive patients and the study's protocol-defined corticosteroid taper.

The panel considers the clinical significance of demonstrating improvement while corticosteroid doses were being reduced. They also discuss the continued separation in outcomes during longer follow-up and note that the onset of effect with B-cell depletion may be slower than that observed with FcRn or complement inhibition.

The conversation then turns to CD20-directed depletion with rituximab. Faculty reviewed the phase 2 BeatMG study, which did not demonstrate the anticipated corticosteroid-sparing benefit in its studied population, while also considering potential limitations related to disease severity and trial design. The panel contrasts those findings with subsequent data evaluating earlier rituximab use and discusses the broader international experience with the therapy.

Particular attention is given to MuSK-positive MG, in which panelists describe substantial and sometimes prolonged clinical responses to rituximab and an association between antibody reduction and clinical improvement. The experts emphasize that the clinical effects of CD20 depletion may differ according to antibody subtype and underlying B-cell biology.

In the next episode, ‘Understanding the Limits of B-Cell Depletion in MG,’ panelists will examine which B-cell populations remain after depletion, the clinical consequences of persistent long-lived plasma cells, and the safety considerations associated with broader immune suppression.