A multipronged Tα1 reset of CD8<sup>+</sup> T cell cytotoxicity against breast cancer.

This study investigated whether Thymosin α1 (Tα1), an endogenous thymic peptide known to modulate immune function, could enhance CD8+ T cell-mediated killing of breast cancer cells. Researchers isolated CD8+ T cells from peripheral blood of ten healthy donors and tested them under four conditions: unstimulated, CD3/CD28-stimulated, Tα1-treated, or exhaustion-rescue. Cytotoxic activity was assessed against MDA-MB-231 breast cancer cells and CD44+ cancer stem-like cells. The study reported that Tα1 treatment significantly increased cancer cell apoptosis, suppressed tumor cell proliferation, and boosted granzyme B secretion compared to CD3/CD28 stimulation alone. In artificially exhausted T cells, Tα1 partially restored effector function and reduced expression of exhaustion markers PD-1, TIM-3, and LAG-3. Complementary bioinformatic analysis of TCGA-BRCA data (n=1,112) using a four-gene Tα1 Response Index correlated with antigen presentation and cytotoxic gene programs. Key limitations include the small donor sample (n=10), use of healthy donor rather than patient-derived T cells, an in vitro experimental design, and the exploratory nature of the transcriptomic index. Results may not directly translate to in vivo or clinical settings.

Why this grade: Despite using human-derived cells (n=10 donors), all functional experiments were conducted in vitro with no in vivo or clinical trial component, limiting direct translation to human outcomes.