The outcome remain somewhat poor for patients with relapsed/refractory acute myeloid leukemia (AML). Here, Joshua Zeidner, MD, of the UNC Lineberger Comprehensive Cancer Center, Chapel Hill, NC, introduces the Phase II trial (NCT02768792) aiming to stimulate a T-cell mediated anti-leukemic immune response using pembrolizumab, a monoclonal antibody that targets the programmed death-1 (PD-1) protein, after high-dose cytarabine (HiDAC) salvage chemotherapy. Dr Zeider discusses how pembrolizumab is well tolerated after HiDAC, with an encouraging response rate observed in a high-risk patient population without apparent additive toxicity.