44 research outputs found

    Synergistic cytotoxicity of fludarabine, clofarabine, busulfan, vorinostat and olaparib in AML cells

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    Combinations of nucleoside analog(s) and DNA alkylating agent(s) are used for cancer treatment as components of pre-transplant regimens used in hematopoietic stem cell transplantation. Their efficacies are enhanced by combining drugs with different mechanisms of action, which also allows a reduction in the individual drug dosages and thus potentially in toxicity to the patient. We hypothesized that addition of SAHA and olaparib, an HDAC- and a PARP-inhibitor, respectively, to the established combination of fludarabine, clofarabine and busulfan would enhance AML cell cytotoxicity. Exposure of the AML cell lines KBM3/Bu2506, MV4-11, MOLM14 and OCI-AML3 to the 5-drug combination resulted in synergistic cytotoxicity with combination indexes < 1. Increased protein acetylation and decreased poly(ADP-ribosyl)ation were observed, as expected. Activation of apoptosis was suggested by cleavage of Caspase 3 and PARP1, DNA fragmentation, increased reactive oxygen species, and decreased mitochondrial membrane potential. The reduction in poly(ADP-ribosyl)ation was independent of caspase activation. Several proteins involved in DNA damage response and repair were downregulated, which may be contributing factors for the observed synergism. The increased phosphorylation of DNAPKcs suggests inhibition of its kinase activity and diminution of its role in DNA repair. A similar synergism was observed in patient-derived cell samples. These findings will be important in designing clinical trials using these drug combinations as pre-transplant conditioning regimens for AML patients

    Nonsteroidal Anti-inflammatory Drug Induced Thrombotic Thrombocytopenic Purpura

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    A 21-year-old male presented to the emergency department after a 5-day history of recurrent vomiting and decreased urine output. History revealed ingestion of ibuprofen. During the diagnostic workup, the following was identified: white blood cell count 13.4 (x10(3)/mcL), hemoglobin 11.9 (x10(6)/mcL) with an MCV of 73 fL, hematocrit 34% and platelets were 31,000/mcL, sodium of 130 mmol/L, potassium of 5.1 mmol/L, chloride of 83 mmol/L, bicarbonate of 21 mmol/L, blood urea nitrogen of 184 mg/dL and creatinine of 19.1 mg/dL. He was later diagnosed with thrombotic thrombocytopenic purpura (TTP) based on the fact that he presented with most components of the TTP pentad (except for fever), which included altered mental status, acute kidney injury, thrombocytopenia, and evidence of red cell fragmentation and his ADAMTS13 level was found to be less than 10% prior to therapy. The patient then received plasma exchange, oral corticosteroids, and hemodialysis, which led to a full recovery of platelet count and renal function

    The Role of Anti-Thymocyte Globulin or Alemtuzumab-Based Serotherapy in the Prophylaxis and Management of Graft-Versus-Host Disease

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    Allogeneic hematopoietic stem cell transplant is an established treatment modality for hematologic and non-hematologic diseases. However, it is associated with acute and long-term sequelae which can translate into mortality. Graft-versus-host disease (GVHD) remains a glaring obstacle, especially with the advent of reduced-intensity conditioning. Serotherapy capitalizes on antibodies which target T cells and other immune cells to mitigate this effect. This article focuses on the utility of two such agents: anti-thymocyte globulin (ATG) and alemtuzumab. ATG has demonstrated benefit in prophylaxis against GVHD, especially in the chronic presentation. However, there is limited impact of ATG on overall survival and it has little utility in the treatment context. There may be an initial improvement, particularly in skin manifestations, but no substantial benefit has been elicited. Alemtuzumab has shown benefit in both prophylaxis and treatment of GVHD, but at the consequence of a more profound immunosuppressive phase, mandating aggressive viral prophylaxis. There remains heterogeneity in the doses and regimens of the agents, with no standardized protocol in place. Furthermore, it seems that once steroid-refractory GVHD has been established, there is little that can be offered to offset the ultimately dismal outcome. Here we present a systematic overview of ATG- or alemtuzumab-based serotherapy in the prophylaxis and management of GVHD
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