Inclusion Criteria:

          1. Written informed consent must be obtained prior to any screening procedures

          2. Male or female patients ≥ 18 years of age who present with one of the following:

             Arms 1-3:

               -  Refractory/relapsed AML following ≥1 prior therapies and are deemed by the
                  investigator not to be candidates for standard therapy, including re-induction
                  with cytarabine or other established chemotherapy regimens for patients with AML
                  (patients who are suitable for standard re-induction chemotherapy or
                  hematopoietic stem cell transplantation and willing to receive it are excluded)

               -  Newly diagnosed AML patients who are suitable for treatment with decitabine
                  (patients who are suitable for standard induction chemotherapy or hematopoietic
                  stem cell transplantation and willing to receive it are excluded)

               -  Intermediate or high risk MDS or MDS/MPN including CMML (patients who are
                  suitable for standard re-induction chemotherapy or hematopoietic stem cell
                  transplantation and willing to receive it are excluded)

             Arms 4-5:

               -  Refractory / relapsed AML following ≥1 prior therapies (Arms 4a & 5a)

               -  Intermediate or high risk MDS or MDS/MPN including CMML who have failed
                  hypomethylating agent therapy (Arms 4b & 5b) (Note: hypomethylating agent failure
                  is defined as progressive disease on hypomethylating agent therapy or lack of
                  clinically meaningful response as deemed by investigator after at least 4 cycles
                  of hypomethylating agent therapy.)

             Arm 6:

               -  Newly diagnosed AML patients who are suitable for treatment with azacitidine
                  (patients who are suitable for standard induction chemotherapy or hematopoietic
                  stem cell transplantation and willing to receive it are excluded) (Arm 6a)

               -  Intermediate or high-risk MDS or MDS/MPN including CMML (patients who are
                  suitable for standard induction chemotherapy or hematopoietic stem cell
                  transplantation and willing to receive it are excluded) (Arm 6b)

          3. Patient has an Eastern Cooperative Oncology Group (ECOG) performance status ≤ 2

          4. Patient must be a candidate for serial bone marrow aspirate and/or biopsy according to
             the institutions guidelines and be willing to undergo a bone marrow aspirate
             and/biopsy at screening, during and at the end of therapy on this study. Exceptions
             may be considered after documented discussion with Novartis.

          5. Arms 1-3: Patients must be fit for standard treatment with decitabine as determined by
             the investigator and as per local decitabine package insert.

          6. Arm 6: Patients must be fit for standard treatment with azacitidine as determined by
             the investigator and as per the local azacitidine package insert.

        Exclusion Criteria:

          1. Arms 1-3 or Arm 6: Patients who have received prior hypomethylating agent treatment
             for AML or MDS.

          2. Patients with active, known or suspected autoimmune disease. Patients with vitiligo,
             type I diabetes, residual hypothyroidism only requiring hormone replacement, psoriasis
             not requiring systemic treatment or conditions not expected to recur should not be
             excluded.

          3. History of, or current drug-induced interstitial lung disease or pneumonitis grade ≥
             2.

          4. Patients who discontinued prior PD-1 or PD-L1 directed therapy due to a treatment
             related toxicity should not be included in the PDR001 containing arms of the study.
             Patients previously exposed to anti-PD-1/PD-L1 treatment who are adequately treated
             for skin rash or with replacement therapy for endocrinopathies should not be excluded.

          5. Systemic antineoplastic therapy (including cytotoxic chemotherapy, alphainterferon,
             kinase inhibitors or other targeted small molecules, and toxinimmunoconjugates) or any
             experimental therapy within 14 days or 5 half-lives, whichever is shorter, before the
             first dose of study treatment.

          6. Systemic chronic corticosteroid therapy (>10 mg/day prednisone or equivalent) or any
             immunosuppressive therapy within 7 days of first dose of study treatment. Topical,
             inhaled, nasal and ophthalmic steroids are allowed.

        Other protocol-defined inclusion/exclusion criteria may apply.