T cell factor 1 (TCF-1), a Wnt pathway transcription factor, maintains CD8+ T cell stemness in the tumor microenvironment and during alloimmunity.36,37 Combination therapy significantly increased intratumoral TCF-1+ T cell fractions versus oHSV alone in a 4T1 breast cancer model (Fig. S11a–c). This evidence concerns the gene CD8A and breast cancer.