Influence of functional polymorphisms of the MDR1 gene on vincristine pharmacokinetics in childhood acute lymphoblastic leukemia

OBJECTIVE: Our objective was to investigate the effect of single nucleotide polymorphisms (SNPs) in the P-glycoprotein MDR1 gene on vincristine pharmacokinetics and side effects in childhood acute lymphoblastic leukemia. METHODS: From 52 of 70 children who participated in a previous study on vincristine pharmacokinetics, patient material was available for investigation of the MDR1 genetic variants. The SNPs C3435T and G2677T were determined by use of polymerase chain reaction-restriction fragment length polymorphism. Vincristine side effects were scored retrospectively from patient records. RESULTS: No association was observed between C3435T or G2677T and vincristine pharmacokinetic variables. When haplotypes were assigned, haplotype 1/1 carriers (3435C/2677G) showed a longer elimination half-life than noncarriers (1156 versus 805 minutes, P =.038). In contrast, haplotype 1/2 carriers (3435T/2677G) had a shorter elimination half-life than noncarriers (805 versus 1180 minutes, P =.044). However, this significance was lost after Bonferroni correction for multiple testing. The haplotypes did not affect the other pharmacokinetic parameters, such as clearance and area under the concentration-time curve, suggesting that the observed effect on elimination half-life is of very limited relevance. Moreover, SNPs in the MDR1 gene did not identify patients with an increased risk for vincristine-induced constipation. CONCLUSION: The genetic variants in the MDR1 gene alone cannot explain the large variability in vincristine pharmacokinetics.     

The putative factor IX gene promoter in hemophilia B Leyden

Hemophilia B Leyden is characterized by low levels of factor IX antigen and activity before the age of 15, whereas after puberty factor IX levels rise at a rate of about 5% per year. A single base substitution (-A----T) at position -20 was identified in the putative promoter of the gene cloned from a patient with hemophilia B Leyden. This nucleotide change was confirmed in a second patient from the same pedigree and was also found in a patient from a second Dutch pedigree with the same hemophilic phenotype. The results indicate that the two Dutch kindreds are related and point to the functional significance of the -20 position for the expression of the human factor IX gene.     

The negative impact of being underweight and weight loss on survival of children with acute lymphoblastic leukemia

Body mass index and change in body mass index during treatment may influence treatment outcome of pediatric patients with acute lymphoblastic leukemia. However, previous studies in pediatric acute lymphoblastic leukemia reported contradictory results. We prospectively collected data on body composition from a cohort of newly diagnosed Dutch pediatric patients with acute lymphoblastic leukemia (n=762, age 2–17 years). Patients were treated from 1997–2004 and the median follow-up was 9 years (range, 0–10). Body mass index at diagnosis was expressed as age- and gender-matched standard deviation scores and on the basis of these scores the patients were categorized as being underweight, of normal weight or overweight. Multivariate analyses showed that patients who were underweight (8%) had a higher risk of relapse [hazard ratio: 1.88, 95% confidence interval (1.13–3.13)], but similar overall survival and event-free survival as patients who had a normal weight or who were overweight. Patients with loss of body mass index during the first 32 weeks of treatment had a similar risk of relapse and event-free survival, but decreased overall survival [hazard ratio: 2.10, 95% confidence interval (1.14–3.87)] compared to patients without a loss of body mass index. In addition, dual X-ray absorptiometry scans were performed in a nested, single-center cohort. Data from these scans revealed that a loss of body mass consisted mainly of a loss of lean body mass, while there was a gain in the percentage of fat. In conclusion, being underweight at diagnosis is a risk factor for relapse, and a decrease in body mass index early during treatment is associated with decreased survival. In addition, loss of body mass during treatment seems to consist mainly of a loss of lean body mass. This study was approved by the Medical Ethical Committee in 1996 (trial number NTR460/SNWLK-ALL-9).     

Long term survivors of childhood cancer: cure and care. The Erice statement

The number of subjects that have successfully completed treatment for a cancer diagnosed during childhood and are entering adulthood is increasing over time. Members of the International Berlin-Frankfurt-Munster (I-BFM) Early and Late Toxicity Educational Committee (ELTEC) invited 45 paediatric cancer experts (representing oncologists, psychologists, nurses, epidemiologists, parents, and survivors) from 13 European countries (with five additional experts from North America) to Erice, Sicily (from October 27 to 29, 2006) to discuss the circumstances in which the word 'cure' should be used when speaking about children with cancer, and when and why continuing follow-up and care may be required. The objective of the gathering was to generate from the personal and professional experience of the participants an overview statement of the group's philosophy of cure and care of survivors of childhood cancer. The ten points reflect what the group considers essential in the survivors' cure and care.     

Comparison of antibiotic resistant and sensitive strains ofHaemophilus influenzae type b in The Netherlands by outer-membrane protein subtyping

The percentage of-lactamase producingHaemophilus influenzae strains from patients with meningitis in The Netherlands increased from 0% in 1975/1976 to 4.6 % in 1985/1986 (n=1559). Twenty-three isolates resistant to ampicillin, penicillin, chloramphenicol, rifampicin and/or tetracycline were subtyped to determine if one resistant strain was spreading. (Sub)typing was performed by capsular typing, analysis of the major outer membrane protein patterns on sodium dodecylsulfate gels (SDS-PAGE subtypes), lipopolysaccharide serotyping and biotyping. The (sub)types of the resistant strains were similar to those of sensitive strains, thus indicating that antibiotic resistant strains develop at random.