Characterization of in vitro and in vivo hypomethylating effects of decitabine in acute myeloid leukemia by a rapid, specific and sensitive LC-MS/MS method

DNA hypermethylation is a common finding in malignant cells and has been explored as a therapeutic target for hypomethylating agents (e.g., decitabine). Detection of changes in DNA methylation might serve as a pharmacodynamic endpoint to establish the biological activity of these agents and predict clinical response. We developed and validated a rapid, sensitive and specific LC-MS/MS method for determination of global DNA methylation (GDM) in vitro and in vivo. Ratios of 5-methyl-2′-deoxycytidine (5mdC) to the internal standard 2-deoxyguanosine (2dG) in mass signal were used to quantify GDM levels. The assay was validated in a linear range from 40 fmol to 200 pmol 5mdC. The intra-day precision values ranged from 2.8 to 9.9% and the inter-day values from 1.1 to 15.0%. The accuracy of the assay varied between 96.7 and 109.5%. This method was initially applied for characterization of decitabine-induced GDM changes in in-vitro-treated leukemia cells. Following exposure to 2.5 μM decitabine, GDM decreased to ∼50% of the baseline value. The clinical applicability of this method was then demonstrated in bone marrow samples from patients with acute myeloid leukemia treated with decitabine. Our data support the use of our LC-MS/MS method for clinical pharmacodynamic determination of changes in GDM in vivo

Improved Nonrelapse Mortality and Infection Rate with Lower Dose of Antithymocyte Globulin in Patients Undergoing Reduced-Intensity Conditioning Allogeneic Transplantation for Hematologic Malignancies

We sought to reduce the risk of infectious complications and nonrelapse mortality (NRM) associated with the use of antithymocyte globulin (ATG) without compromising control of acute graft-versus-host disease (aGVHD) in patients undergoing reduced-intensity conditioning (RIC) transplantation. As part of an ongoing quality improvement effort, we lowered the dose of rabbit ATG from 7.5 mg/kg of ATG (R-ATG) (n = 39) to 6.0 mg/kg of ATG (r-ATG) (n = 33) in association with fludarabine (Flu) and busulfan (BU) RIC transplantation and then monitored patients for adverse events, relapse, and survival. Of the 72 mostly high risk (82%) patients studied, 89% received unrelated donor allografts, 25% of which were HLA-mismatched. No differences in posttransplantation full donor-cell chimerism rates were observed between the 2 ATG-dose groups (P > .05). When R-ATG versus r-ATG patients were compared, we observed no significant difference in the cumulative incidence of grade II-IV aGVHD (32% versus 27%; P = .73) or grade III-IV aGVHD (23% versus 11%; P = .28). However, the r-ATG group had significantly less cytomegalovirus (CMV) reactivation (64% versus 30%; P = .005) and bacterial infections (56% versus 18%; P = .001), a better 1-year cumulative incidence of NRM (18% versus 3%; P = .03), and a trend for better 1-year overall survival (OS) (64% versus 84%; P = .07) compared to R-ATG patients. A seemingly modest reduction in the dose of rabbit ATG did not compromise control of aGVHD or achievement of donor chimerism, but led to a significant decrease in the risk of serious infections and NRM in high-risk RIC allograft recipients

The tumor suppressor PP2A is functionally inactivated in blast crisis CML through the inhibitory activity of the BCR/ABL-regulated SET protein

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Addition of Infliximab to Standard Acute Graft-versus-Host Disease Prophylaxis following Allogeneic Peripheral Blood Cell Transplantation

Infliximab, a chimeric monoclonal antibody (mAb) against tumor necrosis factor (TNF)-α, has shown activity against steroid refractory acute graft-versus-host disease (aGVHD). We conducted a prospective trial of infliximab for the prophylaxis of aGVHD. Patients older than 20 years undergoing myeloablative allogeneic stem cell transplantation (SCT) for hematologic malignancies were eligible. GVHD prophylaxis consisted of infliximab given 1 day prior to conditioning and then on days 0, +7, +14, +28, and +42, together with standard cyclosporine (CSA) and methotrexate (MTX). Nineteen patients with a median age of 53 years were enrolled. All patients received peripheral blood allografts from matched sibling (n = 14) or unrelated donors (n = 5). Results were compared with a matched historic control group (n = 30) treated contemporaneously at our institution. The cumulative incidences of grades II-IV aGVHD in the infliximab and control groups were 36.8% and 36.6%, respectively (P = .77). Rates of chronic GVHD were 78% and 61%, respectively (P = .22). Significantly more bacterial and invasive fungal infections were observed in the infliximab group (P = .01 and P = .02, respectively). Kaplan-Meier estimates of 2-year overall survival (OS) and progression free survival (PFS) for patients receiving infliximab were 42% and 36%, respectively. The corresponding numbers for patients in the control group were 46% and 43%, respectively. The addition of infliximab to standard GVHD prophylaxis did not lower the risk of GVHD and was associated with an increased risk of bacterial and invasive fungal infections