We have previously demonstrated that for various small tumors, Ipilimumab, HL12 and HL32 are comparable in their efficacy in inducing tumor rejection.29 Given the better efficacy of Treg depletion by HL12 and HL32, and given the critical role of Treg in suppressing anti-tumor T cell responses, we re-evaluated the efficacy of different anti-CTLA-4 antibodies in a more challenging setting, i.e., in mice that bare large tumors and thus with a well-established microenvironment. Here, CTLA4 is linked to neoplasm.