Azacitidine Maintenance after Allogeneic Stem Cell Transplantation Is Feasible in Patients with Acute Myeloid Leukemia and Myelodysplasia

Background: 5-Azacidine (5-AZA) is a DNA hypomethylating agent with proven clinical activity in myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). A recent non-randomized study reported promising results with the use of lower doses of 5-AZA as maintenance therapy after hematopoietic stem cell transplantation (HSCT). It is important to note that 5-AZA has an immunomodulatory effect and might enhance the graft-versus-leukemia (GVL) effect. Here, we report the successful use of 5-AZA maintenance following allogeneic HSCT in patients with high risk AML and MDS.

Patients and methods: Nine patients (M=6, F=3; median age=49 (36-65) years ) with high-risk AML (n=6 including 2 abnormal karyotypes) or MDS (n=3 including 1 abnormal karyotype) received 5-AZA as post-transplant maintenance at a dose of 32mg/m2 daily for 5 days every 4 weeks starting at a median time of 100 (30-210) days post-transplant. All patients were in complete remission at initiation of 5-AZA. A median of 12 cycles (1-18) were delivered. Patients’ characteristics, treatment details, response and side effects are summarized in Table I.

Results: After a median follow-up of 19 months post HSCT and 15 months after starting 5-AZA treatment, five patients with normal karyotype are still in CR. Conversely, all three patients with abnormal karyotype rapidly developed disease recurrence while they were receiving 5-AZA after a median of 3 months. Overall, the actuarial 1-year progression free and overall survival rates were 65% and 90%, respectively. 5-AZA was generally well tolerated with only mild thrombocytopenia observed in 2 patients. No clinically evident graft-versus-host disease exacerbation was observed.

Conclusion: These results suggest that Low-dose 5-AZA is an effective maintenance therapy post- allogeneic SCT in high-risk AML and MDS particularly when a normal diploid karyotype is present. The relative lack of efficacy in the presence of an abnormal karyotype is intriguing and questions whether these subjects might benefit from higher doses of 5-AZA or other novel therapies within the context of a well-designed clinical trial. Prospective clinical trials and longer follow-up are needed to confirm these observations.

Stem cell source for all patients: peripheral blood; CR: complete remission; PR: partial remission; CSA: cyclosporine A; MRD: matched related donor; MUD: matched unrelated donor; PBSC: peripheral blood stem cell; CCR: continuous complete remission; FB4: 5 days fludarabine plus 4 days busulfan (130 mg/m2/day); FB3: 5 days fludarabine plus 3 days busulfan (130 mg/m2/day); FB2: 5 days fludarabine plus 2 days busulfan (130 mg/m2/day) ATG: anti-thymoglobuline; DLI: donor lymphocyte infusion.