CD8 and Treg changes should not be interpreted too linearly as individual markers. Bex is not a direct T-cell activator, but an upstream myeloid checkpoint therapy that affects the entire tumor immune microenvironment through macrophages. It can reduce immunosuppression, help the immune system recognize cancer cells better, and improve the function of T and NK cells.
It is therefore more about reprogramming the entire immune network than boosting a single cell type.
That point about the differences between cancer types is important. Different tumors emphasize different suppression mechanisms.