Tethered IL-15 augments antitumor activity and promotes a stem-cell memory subset in tumor-specific T cells

LV Hurton, H Singh, AM Najjar… - Proceedings of the …, 2016 - National Acad Sciences
LV Hurton, H Singh, AM Najjar, KC Switzer, T Mi, S Maiti, S Olivares, B Rabinovich, H Huls…
Proceedings of the National Academy of Sciences, 2016National Acad Sciences
Adoptive immunotherapy retargeting T cells to CD19 via a chimeric antigen receptor (CAR)
is an investigational treatment capable of inducing complete tumor regression of B-cell
malignancies when there is sustained survival of infused cells. T-memory stem cells (TSCM)
retain superior potential for long-lived persistence, but challenges exist in manufacturing this
T-cell subset because they are rare among circulating lymphocytes. We report a clinically
relevant approach to generating CAR+ T cells with preserved TSCM potential using the …
Adoptive immunotherapy retargeting T cells to CD19 via a chimeric antigen receptor (CAR) is an investigational treatment capable of inducing complete tumor regression of B-cell malignancies when there is sustained survival of infused cells. T-memory stem cells (TSCM) retain superior potential for long-lived persistence, but challenges exist in manufacturing this T-cell subset because they are rare among circulating lymphocytes. We report a clinically relevant approach to generating CAR+ T cells with preserved TSCM potential using the Sleeping Beauty platform. Because IL-15 is fundamental to T-cell memory, we incorporated its costimulatory properties by coexpressing CAR with a membrane-bound chimeric IL-15 (mbIL15). The mbIL15-CAR T cells signaled through signal transducer and activator of transcription 5 to yield improved T-cell persistence independent of CAR signaling, without apparent autonomous growth or transformation, and achieved potent rejection of CD19+ leukemia. Long-lived T cells were CD45ROnegCCR7+CD95+, phenotypically most similar to TSCM, and possessed a memory-like transcriptional profile. Overall, these results demonstrate that CAR+ T cells can develop long-term persistence with a memory stem-cell phenotype sustained by signaling through mbIL15. This observation warrants evaluation in clinical trials.
National Acad Sciences