Pembrolizumab and Decitabine for Refractory or Relapsed Acute Myeloid Leukemia

Background: Acute myeloid leukemia (AML) is a cancer of the white blood cells. It is fatal if not treated. Treatment for AML that has not responded to treatment (refractory) or has returned after treatment (relapsed) often do not work. Researchers want to see if an immunotherapy drug, combined with a less intense chemotherapy, may be able to help. Objective: To test if pembrolizumab, in combination with decitabine, is a possible treatment for people with relapsed or refractory AML. Eligibility: Adults 18 years of age and older with refractory AML or relapsed AML. Design: Participants will be first screened for eligibility. The study is counted in 21-day cycles. The initial phase of the study consists of 8 cycles. Participants may be in the study for up to 2 years if they are responding to the treatment. The first 3 weeks of treatment is usually done in the hospital. The rest may be done as an outpatient. Participants will get pembrolizumab at the beginning of each cycle through an IV. Participants will usually get decitabine by IV on days 8 12 and days 15 19 of every other cycle. Participants will give blood samples. Participants will have bone marrow exams. A needle will be inserted into the hip to extract cells from the bone marrow. Some participants may give a sample of saliva from the inside of their cheek. Some participants may give a small skin sample. The top layer of the skin is removed. Some patients may require leukapheresis before starting treatment. This is a procedure to remove leukemia cells in the blood stream.