Safety Study of Oral Azacitidine (CC-486) as Maintenance Therapy After Allogeneic Hematopoietic Stem Cell Transplantation (HSCT) in Participants With Acute Myeloid Leukemia (AML) or Myelodysplastic Syndromes (MDS).

The purpose of the study is to determine the maximal tolerated dose and schedule of CC-486, known as oral azacitidine, in patients with AML or MDS after allogeneic hematopoetic stem cell transplant (HSCT). HSCT is more frequently used in AML or MDS as a potential curative therapy. However, disease recurrence/relapse and graft-versus-host disease (GVHD) remain the principal causes of fatal complications after transplantation. Oral azacitidine has significant activity in MDS and AML. Oral azacitidine has also demonstrated immunomodulatory activity in AML patients after allogeneic HSCT. An oral formulation of oral azacitidine provides a convenient route of administration and an opportunity to deliver the drug over a prolonged schedule.

This is an open-label, multicenter study of oral azacitidine in MDS or AML patients who have undergone allogeneic HSCT. The study consists of three phases: Screening, Treatment and Follow-up. During the Screening phase, the study doctor will do tests to see if the patient is suitable for this study. The patients meeting protocol-specified entry criteria will enter the treatment phase and be assigned to receive one of the oral azacitidine cohorts. The dosing group of 200 mg QD on Days 1 to 7 will be evaluated first (ie, Cohort 1). In the event that unacceptable toxicity occurs in Cohort 1, then oral azacitidine may be evaluated at lower dose levels (eg, 150 mg). If the dosing regimen is confirmed to be safe in Cohort 1, other cohorts will be evaluated sequentially. During the treatment phase, patients will be monitored closely for safety and tolerability. Dosing interruption or delay, dose or schedule reduction, intra-subject dose/schedule escalation or re-escalation may occur on the basis of protocol-specified dosing adjustment guidelines. Safety will be monitored throughout the study at predetermined intervals and as clinically indicated by vital signs, physical examination, performance status, laboratory tests and evaluation of adverse events. The patient can continue to receive the study treatment for up to 12 months provided that they benefit from the study treatment and all protocol-specified criteria are met. However, the patient may receive the study treatment for less than 12 months due to adverse event, disease recurrence or progression. When the study treatment is discontinued, all patients who have received at least one dose of oral azacitidine will be asked to see the study doctor for the treatment discontinuation visit. Thereafter, all patients discontinued from the study treatment will enter the Follow-up phase for safety and survival follow up.