CTLA4 and neoplasm: Taken together, the observed synergy is based on the combination of three mechanisms: 1) RIT off target killing of tumor cells via “bystander” effect (20); 2) RIT directly killing CCR8+ Tregs which allows anti-CTLA4 immunotherapy to become more effective; 3) RIT re-modelling TME by inviting NK cells and anti-tumor macrophages into TME.