Not all T cells are created equally. T cells play a central role in immune response, moving through multiple stages of growth and maturation before they become the killer T cells, or T effector cells, that attack foreign pathogens and cancer cells. While these T effector cells can be engineered to efficiently kill cancer cells, they are short-lived — lasting only days to weeks. This means patients receiving today’s CAR-T therapies, which are largely comprised of modified T effector cells, are likely to relapse unless their initial dose is capable of quickly eliminating every cancer cell in the body.
Poseida has developed a differentiated CAR-T product composed primarily of the earliest-stage T cells, known as stem memory T cells (TSCM cells). TSCM cells are long-lived, self-renewing and multipotent, with the capacity to reconstitute the entire spectrum of T cell subsets, including TEFF cells. They also survive for decades, and potentially for entire lifespans, providing lifelong T cell immunity against some infectious agents.