Clinical Pharmacology of Lisocabtagene Maraleucel in B-cell Malignancies.

Chimeric antigen receptor (CAR) T-cell therapies represent a distinct therapeutic modality whose clinical activity is governed by in vivo cellular kinetics. Lisocabtagene maraleucel (liso-cel) is an autologous CD19-directed, 4-1BB CAR T-cell product in which in vivo expansion plays an important role in clinical pharmacology assessments. Across B-cell malignancies, characterization of liso-cel cellular kinetics demonstrates substantial interindividual variability in expansion, with no single evaluated clinical covariate exerting a clinically meaningful effect. Higher in vivo expansion has been associated with both efficacy and safety outcomes; however, interpretation of these relationships requires careful consideration of end point selection, baseline confounding, and outcome-specific biological context. Particularly, expansion-efficacy relationships are associative rather than causal and are influenced by baseline clinical characteristics and how efficacy end points are defined and assessed. Expansion-safety relationships are end point-dependent, reflecting dynamic immune interactions in the setting of cytokine release syndrome and predominantly downstream toxicity for neurological events. Other clinical pharmacology considerations, including retreatment, persistence, B-cell aplasia, and immunogenicity, further inform the interpretation of liso‑cel expansion within a broader clinical and biological framework. Collectively, these findings indicate that assessing in vivo liso-cel expansion provides important contextual clinical pharmacology information but does not establish it as an independent or deterministic driver of clinical outcomes.