Relapse after glofitamab has a poor prognosis and rates of CD20 loss are high.

Summary: We reviewed cases with aggressive B‐cell non‐Hodgkin lymphoma who relapsed or progressed following glofitamab. The prognosis was poor, with low rates of response to subsequent salvage therapies, and a median overall survival of 4.1 months from the time of progression. There were high rates of CD20 loss (59%) at the time of relapse. In a field where CD20 × CD3 bispecific antibodies are entering routine clinical use, our experience highlights a potential means of resistance. It illustrates both the need to further characterise mechanisms of CD20 loss, and to pursue clinical trials of novel non‐CD20‐directed treatments in this cohort. [ABSTRACT FROM AUTHOR]