W170 - Fate Mapping of Human T Cell Subsets During Expansion for T Cell Therapy

Abstract Text: Adoptive T cell therapies represent a major advance for patients with otherwise-refractory blood cancers. Yet patient responses can vary widely, due in part to the inherent heterogeneity of the manufactured T cell product. Certain T cell subsets/phenotypes in the infusion product can predict clinical efficacy, but it is unclear how and where these desirable cells arise during therapeutic T cell expansion. We investigated the contribution and fate of multiple T cell subsets (naive, central-memory, effector-memory) expanded alone versus together in a pool towards the final T cell product. We used lentivirus-based proteomic barcodes and mass cytometry to follow these populations over time. When expanded together in a pool, all three subsets displayed a greater degree of terminal differentiation and effector cytokine production than when expanded alone. However, only naive CD8 T cells expanded in the pool showed enhanced cytotoxic potential. Meanwhile, pooled naive and effector-memory T cells, but not central-memory T cells, exhibited greater glycolytic activity and oxidative phosphorylation as measured by single-cell metabolic regulome profiling. This coincided with a restoration of their cell cycle progression by the end of an 11-day expansion, compared to their counterparts expanded alone which gradually returned to G0/G1 over time. Overall, these results suggest that pooled expansion may only be beneficial for certain subsets for T cell therapies.