Early Prediction of Subsequent Molecular Response to Nilotinib in Patients with Chronic Myeloid Leukemia: Comparison of the Quantification of BCR-ABL1 Ratios Using ABL1 or GUSB Control Genes.

Molecular monitoring of BCR-ABL1 transcripts is a critical prognostic indicator of treatment response in chronic myeloid leukemia (CML). Quantification of BCR-ABL1 transcripts using ABL1 or GUSB as control genes on the early molecular response (MR) to frontline nilotinib was studied using data from 60 patients with chronic-phase CML from the Evaluating Nilotinib Efficacy and Safety in Clinical Trials as First-Line Treatment (ENEST1st) substudy. Effects of BCR-ABL1/ABL1 and BCR-ABL1/GUSB ratios at early time points as independent variables on subsequent MR were determined by logistic regression analyses and predictive cut-off values determined by receiver operating curve analyses. From day 45, concordance was found for both control genes' early transcript kinetics and ability to predict subsequent deep MR at 18 months. From baseline to 3 months, transcripts descended linearly with both control genes. Use of ABL1 allowed for an earlier prediction (2 months) of subsequent MR than with GUSB (3 months), with cut-off values of 1.5% and 0.19%, respectively. The dynamic determination of BCR-ABL1 transcripts using either internal control gene is valid and predictive of subsequent MR. The use of GUSB to predict an earlier and more accurate response than ABL1 is not supported in the results. Accurate early indicators of MR are essential to identify patients likely to have inferior outcomes who may benefit from treatment with an alternative tyrosine kinase inhibitor.

von Willebrand disease R1374C: type 2A or 2M? A challenge to the revised classification. High frequency in the northwest of Spain (Galicia).

Patients initially diagnosed with type 1 von Willebrand disease (VWD) have been reclassified as type 2 after a more exhaustive analysis in several studies. Our study's objectives were (1) to reanalyze patients that were previously diagnosed as type 1 to achieve a more accurate diagnosis and (2) to compare the von Willebrand factor (VWF) ristocetin cofactor assay (VWF:RCo) and the VWF collagen binding assay (VWF:CB) in order to evaluate the possibility of replacing the former assay with the latter in the diagnosis of VWD. Twenty-one patients from two large unrelated families and 104 normal controls were studied. VWF:Ag, VWF:RCo, FVIII coagulant activity (FVIII:C), bleeding time (BT), PFA(100), and multimeric analysis of VWF were tested. Genetic analysis by sequencing exon 28 on the VWF gene was also carried out. Patients presented lower levels of VWF:Ag and VWF:RCo, a dissociation between VWF:RCo/VWF:Ag, and the presence of all sizes of multimers in plasma VWF. The results for VWF:CB varied depending on the type of collagen used. The genetic analysis showed that the mutation R1374C is responsible for type 2M VWD. A high frequency of the R1374C mutation is observed in northwestern Spain (Galicia). Some types of 2M VWD are misdiagnosed as type 1 VWD. The VWF:CB (with type I collagen) assay was unable to discriminate defective platelet binding of the R1374C VWF. This confirms that VWF:CB cannot substitute for VWF:RCo, and both should be tested when diagnosing VWD.