Developing Lisocabtagene Maraleucel Chimeric Antigen Receptor T-cell Manufacturing for Improved Process, Product Quality and Consistency Across CD19 Hematologic Indications

Background Aims: Autologous chimeric antigen receptor (CAR) T-cell therapies have demonstrated substantial clinical benefit across several hematologic malignancies. However, patient-to-patient variability and heterogeneity of starting cellular material across patient populations and disease indications pose challenges to manufacturing consistency. Lisocabtagene maraleucel (liso-cel) is an autologous, CD19-directed, defined-composition, 4-1BB CAR T-cell product administered at equal target doses of CD8 and CD4 CAR T cells. Here the authors describe the optimization of the liso-cel manufacturing platform for product quality and consistency.

Methods: Leukapheresis starting materials were collected from patients with large B-cell lymphoma, mantle cell lymphoma or chronic lymphocytic leukemia treated with liso-cel in clinical trials (NCT02631044 and NCT03331198). The liso-cel manufacturing process involves selection of CD8 and CD4 T cells from leukapheresis material followed by independent CD8 and CD4 T-cell activation, transduction, expansion, formulation and cryopreservation. Multivariate design of experimental approaches was utilized to optimize process conditions at both specific unit operations and across the process. Flow cytometry methods were used to assess cellular composition, memory phenotypes and cell proliferation. Antigen-specific functions, including cytokine secretion, cytolytic activity and proliferation, were assessed using endpoint assays after independent stimulation of CD8 and CD4 CAR T-cell product components.

Results: Reductions in process duration time, optimization of drug product container and formulation and activation signal optimization led to significantly increased CAR T-cell product viability. The heterogeneity of patient-derived starting material, including low absolute lymphocyte counts in some samples, was reduced through early T-cell purification, leading to median T-cell frequencies >95% in selected materials across disease indications and limited non-T-cell impurities. These changes further increased lineage purity in CD8 and CD4 CAR T-cell drug products. CD8 and CD4 CAR T-cell component lot functional profiles demonstrated multifunctional mechanisms of action, including differential cytokine release, differential cytolytic kinetics and high frequencies of proliferating cells. Correlative analyses demonstrated strong underlying associations between starting material attributes and final CAR T-cell product phenotype.

Conclusions: Despite substantial heterogeneity of starting leukapheresis material quality/composition between individual patients and across disease indications/histologies, the liso-cel manufacturing platform is robust and capable of generating a consistent drug product from diverse starting materials with a single manufacturing platform.