No abstract

We investigated the possibility of using a pharmacologic agent to modulate viral gene expression in order to target radiotherapy to tumor tissue. In a murine xenograft model, we had previously shown targeting of [125I]2'-fluoro-2'-deoxy-beta-D-5-iodouracilarabinofuranoside ([125I]FIAU) to tumors engineered to express the Epstein-Barr virus (EBV)-thymidine kinase (TK). Here we extend those results to targeting of a therapeutic radiopharmaceutical [131I]FIAU to slow or stop tumor growth or to achieve tumor regression. These outcomes were achieved in xenografts with tumors that constitutively expressed the EBV-TK, as well as with naturally-infected EBV tumor cell lines. Burkitt's lymphoma and gastric carcinoma required activation of viral gene expression by pretreatment with bortezomib. Marked changes in tumor growth could also be achieved in naturally-infected Kaposi's sarcoma herpesvirus (KSHV) tumors following bortezomib activation. Bortezomib-induced enzyme-targeted radiation (BETR) therapy illustrates the possibility of pharmacologically modulating tumor gene expression to effect targeted radiotherapy.

The presence of Epstein-Barr virus (EBV) in the tumor cells of some EBV-associated malignancies may facilitate selective killing of these tumor cells. We show that treatment of an EBV ؉ Burkitt's lymphoma cell line with 5-azacytidine led to a dose-dependent induction of EBV lytic antigen expression, including expression of the viral thymidine kinase (TK) and phosphotransferase (PT). Azacytidine treatment for 24 h modestly sensitized the cell line to all nucleosides tested. To better characterize EBV TK with regard to various nucleoside analogues, we expressed EBV TK in stable cell clones. Two EBV TK-expressing clones were moderately sensitive to high doses of acyclovir and penciclovir (PCV) (62.5 to 500 M) and to lower doses of ganciclovir (GCV) and bromovinyldeoxyuridine (BVdU) (10 to 100 M) compared to a control clone and were shown to phosphorylate GCV. Similar experiments in a transient overexpression system showed more killing of cells transfected with the EBV TK expression vector than of cells transfected with the control mutant vector (50 M GCV for 4 days). A putative PT was also studied in the transient transfection system and appeared similar to the TK in phosphorylating GCV and conferring sensitivity to GCV, but not in BVdU-or PCVmediated cell killing. Induction of EBV kinases in combination with agents such as GCV merits further evaluation as an alternative strategy to gene therapy for selective killing of EBV-infected cells.

Purpose: EBV and other herpesviruses are associated with a variety of malignancies. The EBV thymidine kinase (TK) is either not expressed or is expressed at very low levels in EBV-associated tumors. However, EBV-TK expression can be induced in vitro with several chemotherapeutic agents that promote viral lytic induction. The goal of this study is to image EBV-associated tumors by induction of viral TK expression with radiolabeled 2 ¶-fluoro-2 ¶-deoxy-h-D-5-iodouracil-arabinofuranoside (FIAU). Experimental Design: Immunoblot, luciferase reporter assay, and in vitro assay with [

The introduction of plerixafor as a peripheral blood stem cell mobilization agent has allowed more patients with multiple myeloma, non-Hodgkin's lymphoma, and Hodgkin's disease to mobilize sufficient hematopoietic progenitor cells (HPCs) to proceed to autologous transplantation. Because of the high cost of plerixafor, it is not routinely used in all patients undergoing HPC mobilization. If cost were not an issue, an argument could be made that plerixafor could be added to every mobilization regimen, but cost is an issue so in an attempt to be more cost-effective, many centers have limited plerixafor use to patients who have failed or who are predicted to fail collection of adequate numbers of cells by other methods. Additionally, plerixafor is now under investigation both for HPC collection of healthy donors for allogeneic stem cell transplantation and as an adjunct therapy (i.e., chemosensitizing agent) for acute leukemias. This article briefly reviews the role of plerixafor in autologous and allogeneic transplantation as well as its emerging role in the treatment of acute leukemias. Emphasis is placed on the choice of appropriate patients for plerixafor use to assure an adequate stem cell yield while maximizing the cost effectiveness of using plerixafor. The role of prophylactic collections and future areas of research are also presented.

To ensure optimal clinical outcomes for patients while retaining adequate protection for donors, the National Marrow Donor Program developed guidelines specifying that up to 20 mL/kg of bone marrow can be harvested from donors. These guidelines, originally developed for unrelated adult donors, are followed in children as well. We studied the impact of granulocyte colony-stimulating factor (G-CSF) priming on the cellular composition of harvested bone marrow, sought to develop an algorithm to optimize bone marrow harvest volume from pediatric matched sibling donors, and studied the impact of CD34 cell dose on clinical outcomes. We analyzed data from 92 bone marrow harvests and clinical outcomes for 69 sibling recipient-donor duos, The mean age of recipients was 9.85 ± 5.90 years, and that of donors was 11.85 ± 6.36 years. G-CSF priming was not associated with higher yield of CD34 cells/µL. The median CD34 cell count obtained from donors was 700 cells/µL (range, 400-1700 cells/µL) in donors age <6 years, 360 cells/µL (range, 100-1100 cells/µL) in donors age 6 to 12 years, and 300 cells/µL (range, 80-800 cells/µL) in donors age >12 years (P < .001). The number of CD34 cells infused had no impact on traditional clinical outcomes; however, it was significantly related to graft-versus-host disease/relapse/rejection-free survival. Our investigation revealed that ultimately, a CD34 cell count of approximately 3 to 5 × 10/kg was a threshold beyond which increasing CD34 cell dose did not impact outcome. In this study, we addressed the broad question of whether harvesting up to 20 mL/kg of bone marrow from a child donor is truly necessary for optimal outcomes in every pediatric case.

Prior to the introduction of recombinant human erythropoietin (EPO), red blood cell (RBC) transfusions were frequently required when iron and anabolic steroids failed to improve the clinical symptoms of anemia associated with hemoglobin (Hb) levels that were commonly less than 7 g/dL. After the approval of EPO in the US in 1989, the Hb levels of patients on hemodialysis dramatically improved and the need for RBC transfusions decreased significantly. The need for RBC transfusion remains for patients who require an immediate increase in their RBC mass due to symptomatic anemia and is likely to increase due to changes in the management of anemia in dialysis patients resulting from clinical trials data, regulatory changes, and new reimbursement policies for EPO. The safety of the blood supply has greatly improved over the last few decades and the risk of transfusion-transmitted diseases has now been dramatically reduced. Non-infectious complications of transfusion currently cause the majority of morbidity and mortality associated with transfusion in the US. Transfusion also brings a risk of alloimmunization, a particular concern for dialysis patients waiting for kidney transplantation. Knowledge of the risks of RBC transfusions will help clinicians better assess the risks and benefits of transfusing patients with ESRD. This article reviews the modern day infectious and non-infectious risks of allogeneic RBC transfusions.

Introduction: Obtaining vascular access (VA) is a critical part of the therapeutic apheresis (TA) treatment plan. Currently, there are no guidelines for VA decisionmaking and maintenance related to TA procedures. Materials and Methods: A 28-question survey to gather qualitative information