Adoptive T cell therapies face a fundamental limitation: the stem-like memory T cells that provide lasting immunity are notoriously difficult to generate in laboratory conditions. This technical barrier has constrained the durability of cancer immunotherapies and limited their broader clinical application across oncology and infectious diseases.
Researchers have identified a novel pathway for generating stem cell-like memory CD8+ T cells (Tscm) that bypasses conventional CD3/TCR receptor stimulation entirely. Instead of the standard CD3/CD28 co-stimulation approach, this method relies solely on CD28 signaling to drive T cell expansion while preserving stemness characteristics. The technique produces cells with enhanced self-renewal capacity and multipotent differentiation potential compared to conventionally stimulated T cells.
This finding challenges the established immunology paradigm that effective T cell activation requires dual CD3 and CD28 signals. The CD28-only approach appears to maintain cells in a less differentiated state, potentially solving the long-standing problem of T cell exhaustion that plagued earlier therapeutic approaches. The mechanism likely involves differential metabolic programming that favors stemness over immediate effector function.
For cancer immunotherapy, this could represent a significant advance in CAR-T and tumor-infiltrating lymphocyte therapies, where persistence and memory formation determine long-term treatment success. The ability to generate Tscm cells ex vivo may also enhance vaccine responses and provide new tools for treating chronic infections. However, the practical implications remain to be validated in clinical trials, and questions persist about the functional capacity of these CD28-only activated cells in actual disease settings.