Importance of pharmacogenetic markers in the methylenetetrahydrofolate reductase gene during methotrexate treatment in pediatric patients with acute lymphoblastic leukemia

Despite remarkable progress in survival of children with acute lymphoblastic leukemia (ALL) which has reached about 85%, early toxicity and relapse rate remain issues that need to to be resolved. Genetic variants are important factors influencing the metabolism of cytotoxic drugs in ALL treatment. Variants in genes coding for methotrexate (MTX)-metabolizing enzymes are under constant scientific interest due to their potential impact on drug toxicity and relapse rate. We investigated methylenetetrahydrofolate reductase (MTHFR) c.677C gt T and MTHFR c.1298A gt C variants as pharmacogenetic markers of MTX toxicity and predictors of relapse. The study enrolled 161 children with ALL, treated according to the current International Berlin-Frankfurt-Munster group (BFM) for diagnostics and treatment of leukemia and lymphoma protocols. Genotyping was performed using PCR-RFLP and allele-specific PCR assays. Our results revealed similar distributions of MTHFR c.677C gt T and MTHFR c.1298A gt C genotypes among 104 healthy individuals as compared to pediatric ALL patients. A lower incidence of early MTX toxicity was noted in the MTHFR c.677TT genotype (p=0.017), while MTHFR c.1298A gt C genotypes were not associated with MTX toxicity. Carriers of any MTHFR c.677C gt T and MTHFR c.1298A gt C genotypes did not experience decreased overall survival (OAS) or higher relapse rates. Genetic variants in the MTHFR gene are not involved in leukemogenesis in pediatric ALL. The presence of the MTHFR c.677TT genotype was recognized as a predictive factor for decreased MTX toxicity during the intensification phase of therapy. Neither MTHFR c.677C gt T nor MTHFR c.1298A gt C genotypes correlated with an increased number of toxic deaths or relapse rate. Our study emphasizes the importance of implementing pharmacogenetic markers in order to optimize pediatric ALL therapy

Comparison of standard fibrinogen measurement methods with fibrin clot firmness assessed by thromboelastometry in patients with cirrhosis

Background: The Clauss fibrinogen method and thrombin clotting time (TCT) are still routinely used in patients with cirrhosis to define fibrinogen concentration and clotting potential. The thromboelastometric functional fibrinogen FIBTEM assay evaluates the strength of fibrin-based clots in whole blood, providing information on both quantitative deficit and fibrin polymerization disorders. Objective: To compare these three methods of assessing fibrinogen in patients with cirrhosis of different aetiologies, characterized by impairment in fibrinogen concentration as well as functional aberrance. Methods: Sixty patients with alcoholic and 24 patients with cholestatic cirrhosis were included (Child-Pugh score (CPs) A, n = 24; B, n = 32; C, n = 28). All parameters were compared with those from a control group. Maximum clot firmness (MCF) in the FIBTEM test was assessed in regard to its relevance in detection of qualitative fibrinogen disorders in comparison with results obtained by standard measurement methods, i.e. the Clauss fibrinogen method and TCT. Results: With increased cirrhosis severity, fibrinogen and FIBTEM-MCF levels significantly declined (p = 0.002), while TCT was significantly prolonged (p = 0.002). In all CPs groups, fibrinogen strongly correlated with FIBTEM-MCF (r = 0.77, r = 0.72, r = 0.74; p lt 0.001), while cross-correlations of other assays were highly variable. The prevalence of decreased FIBTEM-MCF values ( lt 9 mm) was significantly higher in advanced CPs categories (p = 0.027), whereby the highest prevalence was detected in patients with CPsC (10/16; 62.5%). Nine of the 16 patients with decreased FIBTEM-MCF values had also decreased fibrinogen levels, while in the remaining 7 patients fibrinogen levels were within the reference range, indicating the possible presence of qualitatively altered fibrinogen that could be detected by FIBTEM-MCF. Conclusions: FIBTEM-MCF may be considered as a reliable alternative to standard plasma fibrinogen measurement in cirrhotic patients, especially in evaluating fibrin polymerization disorders in these patients. Further studies are needed to evaluate the usefulness of this assay in predicting bleeding complications in cirrhotic patients as well as monitoring replacement treatment