Although an early study conducted by Motoyoshi et al. indicated that low dose administration of CTX to tumor-free C3H/HeN mice resulted in a notable decrease of these cells [33], it is worth mentioning that in clinical settings, metronomic cyclophosphamide treatment for three months caused a short-term Tregs reduction in the peripheral blood of breast cancer patients, along with an enhanced expansion of CD4+ and CD8+ T effector cells [34]. This evidence concerns the gene CD8A and breast cancer.