Research conducted by Davids demonstrated that CTLA-4-specific antibody ipilimumab in treating AML patients who relapsed following allo-HSCT can promote the infiltration of cytotoxic CD8+ T lymphocytes and the expansion of Teff subsets, suggesting that ipilimumab is feasible for managing drug-resistant relapsed patients [40]. Here, CTLA4 is linked to acute myeloid leukemia.