CTLA4 and neoplasm: In addition, the clinical efficacy of the monoclonal antibody ipilimumab (anti‐CTLA‐4) in patients with clinical melanoma is associated with selective depletion of Treg cells based on the FcγR‐dependent mechanism and an increase in the tumor‐infiltrating CD8+ T/Treg cell and Teff/Treg ratios.275