Current Insights of Post-Infusion CAR T Expansion and Persistence for Large B-Cell Lymphoma

CD19 directed chimeric antigen receptor (CAR) T-cell therapy is standard of care for relapsed or refractory large B-cell lymphoma. CAR T-cell persistence and activity are associated with outcomes for patients with relapsed B-acute lymphoblastic leukaemia (B-ALL), but the association between expansion kinetics and outcome is less clear in the setting of large B-cell lymphoma. CAR T-cell expansion and persistence have been measured in both clinical trials and real-world settings, but the clinical relevance and applicability of these measurements remain unclear. There is increasing evidence that the in vivo kinetics of CAR T-cells post-infusion do offer important predictive insights into patient outcomes; despite this, limitations remain given the heterogeneity in methodology and timing of measurement. This review will summarise methodologies utilised to measure CD19 directed CAR T-cell expansion and persistence in vivo, in addition to the clinical implications of these measurements as currently described.