These observations suggest that therapeutic effect of anti-GITR-based immunotherapy depends on ablation of an initial pool of tumor-infiltrating Tregs which can be later replaced by a more diverse but minor population of Tregs bearing TCRs able to compete with Teffs for recognition of tumor-associated antigens and thus be responsible for a failure to eradicate the tumor completely. This evidence concerns the gene TNFRSF18 and neoplasm.