CTLA4 and acute myeloid leukemia: Finally, as our protocol was designed to study a cohort of AML patients who may be considered as candidates for maintenance immunotherapies to prevent relapse, we sought to assess expression of cell surface immune checkpoint markers, namely, PD-1, TIM3, CTLA4, and 4-1BB in AML at baseline and in healthy donors on various CD8+ T-cell populations.