High-dose ascorbate and arsenic trioxide selectively kill acute myeloid leukemia and acute promyelocytic leukemia blasts in vitro.

The use of high-dose ascorbate (ASC) for the treatment of human cancer has been attempted several decades ago and has been recently revived by several in vitro and in vivo studies in solid tumors. We tested the cytotoxic effects of ASC, alone or in combination with arsenic trioxide (ATO) in acute myeloid leukemia (AML) and acute promyelocytic leukemia (APL). Leukemic cell lines and primary blasts from AML and APL patients were treated with graded concentrations of ASC, alone or in association with standard concentration (1 µM) of ATO. The ASC/ATO combination killed myeloid blasts, including leukemic CD34+ cells, while sparing CD34+ progenitors obtained from normal cord blood and bone marrow. Actually, approximately one-third (11/36) of primary AML cases were highly sensitive to the ASC/ATO combination. The mechanism of cell killing appeared to be related to increased oxidative stress and overproduction of ROS in a non-quantitative fashion, which resulted in induction of apoptosis. These effects were reverted by the addition of the antioxidant N-Acetyl-Cysteine (NAC). In the APL NB4 model, ASC induced direct degradation of the PML and PML/RARA proteins via caspase activation, while the transcriptional repressor DAXX was recruited in re-constituted PML nuclear bodies. Our findings encourage the design of pilot studies to explore the potential clinical benefit of ASC alone or in combination with ATO in advanced AML and APL.

The Management of Membranous Glomerulopathy in Allogeneic Stem Cells Transplantation: Updated Literature

BACKGROUND: membranous glomerulopathy (MG) is an immunomediated disorder which accounts for the most common cause of nephrotic syndrome (NS) following allogeneic hematopoietic stem cell transplantation (HSCT). OBJECTIVE AND METHODS: to provide an update on the issue by reviewing pertinent literature on the MEDLINE database. RESULTS: sixty-nine post allogenic HSCT patients (42 male) with MG were identified. The median age was 43 (5 to 68) years. Time interval from allogenic HSCT to MG diagnosis ranged from 3 to 134 months (median 17). Most MG patients had a history of acute (70%) or chronic (84%) graft versus host disease (GVHD). Corticosteroids and cyclosporine were the most common therapeutic agents used in this setting; alternative therapies, including rituximab, were given to a lower number of patients. Outcome data were available in 64 out of 69 MG patients; 38 (59%) and 18 (28%) patients achieved a complete and a partial response respectively, whereas treatment failure was recorded in the remaining 8 (13%). CONCLUSION: MG after allogenic HSCT appears to be associated with a sub clinical or overt cGVHD, which follows the discontinuation of immunosuppressive prophylaxis. Although a standard therapeutic approach has not been established, the application of available measures can induce favorable response in more than 80% of affected patients, but treatment-failure and progressive deterioration of the renal function may occur in about one fifth of cases.