Decitabine And Modified CAG Regimen Plus Haplotype Identical Donor Lymphocyte Infusion As Induction Chemotherapy For Elderly Patients With Newly Diagnosed Acute Myeloid Leukemia

Objective: The elderly patients with acute myeloid leukemia (AML), accounting forabout55%of all AML patients, often have a high chemotherapy-related mortality and alow survival. An effective and less toxic induction therapy is required for the treatmentof elderly patients with AML. We conducted a prospective single-arm open-labelclinical trial of decitabine and modified CAG (cytarabine, aclacinomycin and G-CSF)chemotherapy plus haplotype identical donor lymphocyte infusion regimen as inductionchemotherapy in elderly patients with AML. The efficacy and safety of the regimenwere evaluated. The effects of decitabine and G-CSF in combination in human myeloidleukemia cell lines were explored.Methods: A total of20elderly patients with newly diagnosed AML from April,2012toMarch,2013were enrolled. Clinical characteristics, response to the regimen,treatment-related adverse events and graft-versus-host disease (GVHD) were analyzed.Four myeloid leukemia cell lines (Kasumi-1、SKNO-1、THP-1and U937) were treatedwith no drugs, G-CSF alone, decitabine alone, decitabine and G-CSF, respectively. Aftertwo days of treatments, cell apoptosis and differentiation of the leukemia cell lines werequantified by flow cytometry. Cell viability was measured at24h,48h and72h aftertreatments by Cell Counting Kit-8. Colony formation assay was conducted in Kasumi-1and THP-1cells. Real-time quantitative RT-PCR and flow cytometry were used toobserve the changes of gene CSF3R (G-CSF receptor) in the mRNA and protein levels.Bisulfite sequencing was performed to study the methylation status in the5’UTR ofCSF3R.Results: The average age of all patients was65years (range57-77years). Seventeenpatients (85%) had at least one poor prognostic factor. After the first cycle of theregimen,14patients (70%) achieved CR,5patients (25%) achived partial remission(PR), and the overall response rate was95%(19/20). After the second cycle of theregimen, a total of17patients achieved CR, CR rate was85%. The most common adverse event was grade3or4myelosuppression. The median recovery time ofneutrophils and platelets were11days and15days, respectively, after the first cycle ofthe regimen. The median WBC and PLT at sixteen different time points of the first cycleof the regimen were above1.0×109/L and above20×109/L, respectively. No patient wastransferred to the intensive care unit and no treatment-related death occured. Themedian mononuclear cells and CD3+T cells infused in the first cylce were1.230×108/kgand0.949×108/kg, respectively. No acute or chronic GVHD was observed in any of thepatients during the entire treatment. Decitabine significantly inhibited the proliferationand colony formation of myeloid leukemia cell lines, and induced cell differentiationwithout causing obvious apoptosis. G-CSF did not affect the effect of decitabine in theinhibition of cell proliferation and colony formation in myeloid leukemia cell lines, butmarkedly increased the induced cell differentiation of decitabine. Decitabineup-regulated the expression of CSF3R in mRNA level, but did not increase the level ofexpression of the protein. The5’UTR of CSF3R was hypomethylated in the myeloidleukemia cell lines.Conclusion: For elderly patients with AML, DAC and modified CAG regimen plushaplotype identical donor lymphocyte infusion can result in a high CR rate, a shortduration of pancytopenia and no GVHD. The regimen is an effective and safe inductiontherapy for elderly patients with AML. G-CSF markedly increase the induced celldifferentiation of decitabine in the myeloid leukemia cell lines, which may be a reasonof the good effect of the clinic regimen.