To Assess the Safety and Tolerability of INCB000928 in Participants With Myelodysplastic Syndromes or Multiple Myeloma.

Inclusion Criteria:

   - Agreement to avoid pregnancy or fathering children.

   - Participants who are transfusion-dependent or present with symptomatic anemia

For MDS participants:

   - Ineligible to receive or have not responded to available therapies for anemia such as
   ESAs or lenalidomide.

   - Not requiring cytoreductive therapy other than hydroxyurea.

   - BM and peripheral blood myeloblast count < 10%.

   - Histologically confirmed diagnosis of the MDS, CMML and unclassifiable MDS/MPN overlap
   syndromes.

For MM participants:

   - Histologically confirmed diagnosis of MM.

   - After failure of available standard treatments such as alkylating agents,
   glucocorticoids, immunomodulatory drugs (lenalidomide,pomalidomide, or thalidomide),
   proteasome inhibitors (bortezomib or carfilzomib), and daratumumab.

Exclusion Criteria:

   - Any prior allogeneic stem cell transplantation or a candidate for such
   transplantation.

   - Any major surgery within 28 days before the first dose of study drug.

   - Any prior chemotherapy, immunomodulatory drug therapy, immunosuppressive therapy,
   biological therapy, endocrine therapy, targeted therapy, or antibody or
   hypomethylating agent to treat the participant's disease within 5 half-lives or 28
   days (whichever is shorter) before the first dose of study drug.

   - Undergoing treatment with another investigational medication or having been treated
   with an investigational medication within 28 days before the first dose of study drug.
   -Undergoing treatment with ESAs, granulocyte colony-stimulating factor or
   granulocyte/macrophage colony-stimulating factor, romiplostin, or eltrombopag at any
   time within 28 days before the first dose of study drug.

   - Undergoing treatment with a strong or potent inhibitor or inducer of CYP3A4/5 within
   28 days or 5 half-lives (whichever is longer) before the first dose of study drug or
   expected to receive such treatment during the study.

   - History of clinically significant or uncontrolled cardiac disease.

   - History or presence of an abnormal ECG that, in the investigator's opinion, is
   clinically Meaningful.

   - Presence of chronic or current active infectious disease requiring systemic
   antibiotic, antifungal, or antiviral treatment.

   - Diagnosis of chronic liver disease.