In addition to demonstrating the specificity of PD-1+CD8+ TSTs sorted in freshly extracted TILs, a study analyzed the dynamic changes of tumor-specific CD8+ T cells in patients who received CD8+ TIL-transfer therapy and were observed for up to 1 year, and the investigators found that the persisting T cell subpopulations after tumor-specific CD8+ TIL treatment were mostly multifunctional, with a stable partially differentiated phenotype and high expression levels of PD-1 (29). This evidence concerns the gene PDCD1 and neoplasm.