Current Allogeneic Hematopoietic Stem Cell Transplantation for Pediatric Acute Lymphocytic Leukemia: Success,Failure and Future Perspectives—A Single-Center Experience, 2008 to 2016

Hematopoietic stem cell transplantation (HSCT) is the only curative option for a subset of patients with high-risk or relapsed acute lymphoblastic leukemia (ALL). Given evolving practices, it is important to continually evaluate outcomes for pediatric ALL following HSCT. Outcomes after HSCT are influenced by the type of donor used as this determines the degree and method of T cell depletion used and, consequently, specific transplant-related morbidities. We retrospectively analyzed HSCT data from our center for transplants performed between January 2008 and May 2016, comparing outcomes among different donor types. One hundred and twenty-four pediatric patients underwent HSCT from a matched sibling donor (MSD; n?=?48), an unrelated matched donor (UMD; n?=?56), or a haploidentical donor (n?=?20). We observed a similar 3-year event-free survival (EFS) for MSD recipients (of .64) and for UMD recipients (.62), but a significantly lower EFS for recipients of haploidentical transplants (.35; P?=?.01). Relapse was the main cause of HSCT failure and was significantly higher in the haploidentical donor group (.47 versus .19 for MSD and .24 for UMD; P?=?.02). Treatment-related mortality was evenly distributed among the donor groups (.17, .16, and .15 for the MSD, UMD, and haploidentical groups, respectively). Rates of infection-related mortality were lower than previously reported. Relapse is the main obstacle for successful HSCT in the contemporary era, and this effect is most evident in recipients of haploidentical donor grafts. Newer methods to improve graft-versus-leukemia effect are being evaluated and will need to be incorporated into the management of high-risk patients.     

Comparison of the expression of a mutant dihydrofolate reductase under control of different internal promoters in retroviral vectors.

To determine the effect of different promoters on the expression of an altered dihydrofolate reductase (DHFR) gene conferring methotrexate (MTX) resistance in different cell types, double-copy retroviral vectors were constructed carrying a murine mutant DHFR under the control of five different promoters, i.e., human adenosine deaminase (ADA), simian virus 40 (SV40), thymidine kinase (TK), human beta-actin, and cytomegalovirus (CMV). Their expression was compared in NIH-3T3 cells, three human leukemia cell lines, and mouse bone marrow. The variant DHFR is readily expressed from these various promoters in retroviral vectors at a selectable level. In 3T3 cells, the DHFR constructs containing the SV40 promoter conferred the highest levels of resistance to MTX. In K562 and Raji cells, the construct with the TK promoter produced the highest level of resistance. However granulocyte-macrophage colony-forming unit (CFU-GM) colonies from mouse marrow were more resistant to MTX when infected with vectors containing the SV40 promoter and ADA promoter as compared to the other promoter constructs. These studies show that mouse fibroblast cell lines such as NIH-3T3 do not predict the effectiveness of retroviral-mediated gene transfer for marrow progenitor cells, and that the activity of retroviral vector-encoded promoters vary in an unpredictable manner from cell type to cell type. Possible implications for basic gene transfer studies and clinical applications are discussed.     

The handwriting performance of children with NF1

The objective of this study was to analyze the process and product of handwriting among children with Neurofibromatosis Type 1 (NF1) in comparison to those of Typically Developing (TD) children. Children with NF1 are at risk for some cognitive deficits, a wide range of deficits in perceptual skills and, motor and visual-motor integration skills which may interfere with handwriting competency, which is an essential ingredient for success at school. Participants were 30 NF1 children and 30 age and gender matched TD children, between the ages 8 and 16.08. The handwriting performance of children with NF1 was evaluated with the Beery–Buktenica Developmental Test of Visual-Motor Integration (VMI), for copying text and free style writing tasks, using: (1) Computerized Penmanship Evaluation Tool (ComPET) to assess mechanical aspects of the writing process. (2) The Hebrew Handwriting Evaluation (HHE) to examine product legibility. (3) The Six-Trait Writing Model to judge the quality of the written product. Significant differences between the NF1 children and the control group were found in the process and product measures. Significant correlations were found between the VMI, the ComPET, the HHE and the Six-Trait Writing Model variables for both groups. We suggest a possible relationship between executive dysfunction and poor performance in handwriting.