INCB000928 Administered as a Monotherapy or in Combination With Ruxolitinib in Participants With Anemia Due to Myeloproliferative Disorders

Inclusion Criteria:

• Participants with MF who are transfusion-dependent or present with symptomaticanemia, defined as follows:

1. Anemia: An Hgb value < 10 g/dL demonstrated during screening recorded on 3separate occasions with at least 7 days between measurements (Note: RBCtransfusion must be at least 2 weeks before the Hgb measurement duringscreening).

2. Transfusion-dependent: Participant has received at least 4 units of RBCtransfusions during the 28 days immediately preceding Cycle 1 Day 1 OR hasreceived an average of at least 4 units of RBC transfusions in the 8 weeksimmediately preceding Cycle 1 Day 1, for an Hgb level of < 8.5 g/dL, in theabsence of bleeding or treatment-induced anemia. In addition, the most recenttransfusion episode must have occurred in the 28 days before Cycle 1 Day 1.

• ECOG performance status score of the following:

1. 0 or 1 for the dose-escalation stages.

2. 0, 1, or 2 for the dose-expansion stage.

• Life expectancy is greater than 6 months

• Agreement to avoid pregnancy or fathering children.

• Ineligible to receive or have not responded to available therapies for anemia suchas ESAs.

• For TGA:

• Participants previously treated with JAK inhibitors for at least 12 weeks.

• Participants with intermediate-2 or high DIPSS MF according to IWG-MRT criteria.

• For TGB:

• Participants must have been on a therapeutic and stable regimen of ruxolitinib forat least 12 consecutive weeks immediately preceding the first dose of studytreatment.

• Participants with intermediate-1, intermediate-2, or high DIPSS MF according toIWG-MRT criteria.

• For TGC:

• Participants must be JAK inhibitor treatment naive (no prior treatment with any JAKinhibitor) and have an indication for initiation of ruxolitinib treatment.

• Participants with intermediate-1, intermediate-2, or high DIPSS MF according toIWG-MRT criteria.

Exclusion Criteria:

• Undergone any prior allogenic or autologous stem cell transplantation or a candidatefor such transplantation.

• Any prior chemotherapy, immunomodulatory drug therapy, immunosuppressive therapy,biological therapy, endocrine therapy, targeted therapy, antibody or hypomethylatingagent to treat the participant's disease, with the exception of ruxolitinib for TGBonly, within 5 half-lives or 28 days (whichever is shorter) before the first dose ofstudy treatment.

• Laboratory Values outside of protocol defined range at screening.