Nivolumab With Chemotherapy in Refractory MDS

Inclusion Criteria: * Patients with myelodysplastic syndrome (MDS) (up to 20% blasts) of any risk. Patients with lower risk MDS (low and int-1 by IPSS) should have failed prior non-hypomethylating agent therapy (ie growth factors or lenalidomide). Patients with higher risk MDS (int-2 or high by IPSS) should have failed prior at least one therapy with a hypomethylating agent or Ara-C. * Age 18 years or older. * No severe organ dysfunction: creatinine \<=2.5 x ULN; serum bilirubin \<=2.5 x ULN; AST and ALT \<=5 x ULN. * Karnofsky index \>=70% * Females of childbearing potential must have a negative serum or urine beta human chorionic gonadotrophin (beta-hCG) pregnancy test result within 24 hours prior to the first dose of treatment and must agree to use an effective contraception to avoid pregnancy for 24 weeks * Males who have partners of childbearing potential must agree to use an effective contraceptive method during the study and for 24 weeks after the last dose of nivolumab. Exclusion Criteria: * Another malignancy requiring treatment at the time of inclusion * History of interstitial lung disease or pneumonitis * Patients with any other known concurrent severe and/or uncontrolled medical condition (e.g. uncontrolled diabetes; cardiovascular disease including congestive heart failure NYHA Class III or IV, myocardial infarction within 6 months, and poorly controlled hypertension; chronic renal failure; or active uncontrolled infection) which, in the opinion of the investigator could compromise participation in the study * Active, known or suspected autoimmune disease requiring treatment at the time of inclusion * Pregnancy or breastfeeding * Patients unwilling or unable to comply with the protocol * Somatic or psychiatric disorder making the patient unable to sign informed consent * Prior treatment with anti-PD-1, anti-PD-L1, or anti-CTLA4 therapy