Predictors of Early Thrombotic Events in Adult Patients with Acute Myeloid Leukemia: A Real-World Experience.

Information regarding the incidence and the prognostic impact of thrombotic events (TE) in non-promyelocytic acute myeloid leukemia (AML) is sparse. Although several risk factors associated with an increased risk of TE development have been recognized, we still lack universally approved guidelines for identification and management of these complications. We retrospectively analyzed 300 consecutive patients with newly diagnosed AML. Reporting the incidence of venous TE (VTE) and arterial TE (ATE) was the primary endpoint. Secondarily, we evaluated baseline patient- and disease-related characteristics with a possible influence of VTE-occurrence probability. Finally, we evaluated the impact of TE on survival. Overall, the VTE incidence was 12.3% and ATE incidence was 2.3%. We identified three independent predictors associated with early-VTE: comorbidities (p = 0.006), platelets count >50 × 109/L (p = 0.006), and a previous history of VTE (p = 0.003). Assigning 1 point to each variable, we observed an overall cumulative incidence of VTE of 18.4% in the high-risk group (≥2 points) versus 6.4% in the low-risk group (0−1 point), log-rank = 0.002. Overall, ATE, but not VTE, was associated with poor prognosis (p < 0.001). In conclusion, TE incidence in AML patients is not negligible. We proposed an early-VTE risk score that could be useful for a proper management of VTE prophylaxis.

In BCR-ABL1 Positive B-Cell Acute Lymphoblastic Leukemia, Steroid Therapy Induces Hypofibrinogenemia.

Hypofibrinogenemia (HF) in adult acute lymphoblastic leukemia (ALL) of B lineage is uncommon and mostly associated with asparaginase (ASP) delivery. Since we noticed a significant reduction in fibrinogen (FBG) plasma levels even before the first ASP dose, we aim to assess the levels of FBG during induction treatment and explore if the FBG fall correlated with therapies other than asparaginase and/or specific leukemia biological features. We retrospectively analyzed FBG levels in 115 patients with B-ALL. In 74 (64%) out of 115 patients FBG decline occurred during the steroid prephase. In univariate analysis, such a steroid-related HF was significantly associated with BCR-ABL1 rearrangement (p = 0.00158). None of those experiencing HF had significant modifications of liver function tests during induction treatment. Our retrospective study suggests that in B-ALL, steroid therapy can also induce HF and that such an event is preferentially observed in patients carrying BCR-ABL1 rearrangements. The pathogenesis of this phenomenon is still unclear. We attempt to explain it by applying the International Society of Thrombosis and Hemostasis-Disseminated Intravascular Coagulation score (ISTH-DIC score); nonetheless additional studies are needed to clarify further the mechanisms of HF in this subset of patients.

Could MicroRNA polymorphisms influence warfarin dosing? A pharmacogenetics study on mir133 genes.

MicroRNAs are small single stranded molecules that play a crucial role in regulation of physiological and pathological processes. Recent studies showed that VKORC1 gene contains an highly evolutionary conserved binding site for mir-133. Moreover, in human hepatocytes mir-133 is constitutively co-expressed with VKORC1. Since VKORC1 protein is the target of warfarin treatment, the aim of this study was to verify if genetic variations in MIR133A1, MIR133A2 and MIR133B could contribute to warfarin dose variability. By direct sequencing, we identified 4 SNPs in MIR133A2 gene and 1 SNP in MIR133B gene. Three SNPs in MIR133A2 were in complete linkage disequilibrium and correlated with warfarin dose: indeed, for each SNP, patients carrying the GA or AA genotype required a MWWD significantly higher than the wildtype genotype (P=0.019). We also inferred the haplotypes in MIR133A2 gene. The GC haplotype required a MWWD significantly lower than AT haplotype (P=0.012). The multiple linear regression analysis confirmed that rs45547937 (as tag SNP) in MIR133A2 could be involved in warfarin dosing variability, (P=0.016). These results seem to suggest that also polymorphisms in miRNA precursors may potentially affects drug response variability.

Resequencing of VKORC1, CYP2C9 and CYP4F2 genes in Italian patients requiring extreme low and high warfarin doses.

PURPOSE: The aim of the present study was to investigate the genetic variability of VKORC1, CYP2C9 and CYP4F2 genes in patients who required a very low and high warfarin dose, in order to identify novel variants that could help to explain the particular extreme dose requirements. METHODS: Among patients followed and treated with warfarin at the Center of Haemostasis and Thrombosis of the PTV, we selected twelve patients showing a high divergence from warfarin standard doses required to achieve the therapeutic effect. All VKORC1, CYP2C9 and CYP4F2 coding regions, 3' and 5' UTR and exon/intron boundaries were analyzed by direct sequencing. RESULTS: The 1173T and -1639A allele variants in VKORC1 gene, associated with warfarin sensitivity, were present, as expected, mostly in low dose patients while 3730A allele, linked to warfarin resistance, has been found only in high dose patients. Interestingly, we found that three out of six low dose subjects presented CYP2C9*3/*3 homozygous genotype, very rare in Caucasians. Besides these common polymorphisms, we identified 5 SNPs in CYP2C9 gene and 19 SNPs in CYP4F2 gene. Among these, all polymorphisms identified in CYP2C9 gene were present only in low dose patients and three of them resulted in linkage with CYP2C9*2 and CYP2C9*3. Regarding CYP4F2 SNPs, we did not observe differences between the high and low dose patients. At the end, the whole sequencing did not reveal any novel polymorphism/mutation. CONCLUSION: Further studies are required to identify other genetic factors contributing to extreme warfarin requirement.

Characterization of a novel CYP2C9 gene mutation and structural bioinformatic protein analysis in a warfarin hypersensitive patient.

Warfarin (coumadin) is a worldwide-prescribed anticoagulant for the long-term treatment and prevention of thromboembolic events, presenting a great interindividual variability in the required dose. It is known that both environmental and genetic factors influence the dose necessary for the therapeutic effect. Herein we describe a pharmacogenetic study conducted on an Italian patient with warfarin hypersensitivity, who required a very low dosage to achieve therapeutic anticoagulation effect. We genotyped common polymorphisms in VKORC1, CYP2C9, and CYP4F2 genes, known to be involved in warfarin dosing. As the patient resulted in a mixture of low-dosing and high-dosing polymorphic variants, we searched for rare mutations by direct sequencing of the same genes. We identified in the CYP2C9 gene, a novel mutation in heterozygote status, c.374G>T, which produces the Arg125Leu substitution. We have observed, through an electrostatic analysis, that the new mutation produces an electrostatic alteration on the cytochrome surface.

CYP4F2 genetic variant (rs2108622) significantly contributes to warfarin dosing variability in the Italian population.

INTRODUCTION: It is known that warfarin treatment is problematic, due to its narrow therapeutic range and to the great interindividual variability. Numerous papers have shown the important contribution of CYP2C9 and VKORC1 genetic variants to this variability. Recently, a new SNP within the CYP4F2 gene was found associated with warfarin dose in the USA. AIMS: The aim of our work was to replicate this study in the Italian population and to assess the new CYP4F2 variant relative contribution in explaining warfarin dose variability with respect to CYP2C9 and VKORC1 genetic variants together with age and weight. MATERIALS & METHODS: CYP4F2 rs2108622 genotyping was performed by allelic discrimination assay by TaqMan technology. Analysis of variance and multiple linear regression analyses were carried out to examine the contribution of genetic and nongenetic factors. RESULTS: Our TT patients require 5.49 mg/day versus 2.93 mg/day of our CC patients. Analysis of variance indicates that about 7% of mean weekly warfarin dose variance is explained by CYP4F2 genotype. Our linear regression model including CYP4F2, CYP2C9 and VKORC1 genetic variants, age and weight, explains 60.5% of the interindividual variability. CONCLUSION: Our data confirm and strengthen the role of this variant.

Thrombin-activatable fibrinolysis inhibitor polymorphisms and recurrent pregnancy loss.

OBJECTIVE: To investigate the possible association between selected thrombin-activatable fibrinolysis inhibitor (TAFI) single nucleotide polymorphisms (SNPs) and recurrent pregnancy loss (RPL). DESIGN: Case-control study. SETTING: University hospital. PATIENT(S): One hundred fifty-eight women (86 cases and 72 controls). INTERVENTION(S): Determination of TAFI SNPs -438A/G, +505A/G, +1040T/C, +1542C/G, and +1583A/T by polymerase chain reaction (PCR) reactions and sequencing analysis performed on peripheral blood samples. MAIN OUTCOME MEASURE(S): Analysis of the genotype and allele frequencies of TAFI SNPs -438A/G, +505A/G, +1040T/C, +1542C/G, and +1583A/T in women with and without RPL. RESULT(S): Genotype and allele frequencies of TAFI +505 and +1583 SNPs were significantly different in women with RPL compared with control women. The frequencies of the +505A/A and +505G/G genotypes were 1.2% and 61.6% in women with RPL and 13.9% and 43.1% in control women, respectively. The frequencies of the +1583A/A and +1583T/T genotypes were 1.2% and 61.6% in women with RPL and 13.9% and 45.8% in control women, respectively. The genotype and allele frequencies at TAFI position -438, +1040, and +1542 were not significantly different between RPL and control women. CONCLUSION(S): The SNPs leading to increased TAFI levels are associated with a reduced risk of RPL. It is possible that TAFI is involved in RPL.

Allelic variants in the CYP2C9 and VKORC1 loci and interindividual variability in the anticoagulant dose effect of warfarin in Italians.

INTRODUCTION: Warfarin is currently considered to be the anticoagulant of choice in the long-term treatment and prevention of thromboembolic events. However, it presents a narrow therapeutic range and a great interindividual dose variability. We investigated the influence of variants of the VKORC1 and CYP2C9 loci on the mean weekly warfarin dose (MWWD) required to reach stabilized therapeutic international normalized ratio, in order to confirm and to estimate the contribution of common genetic variability of these two genes in an Italian population and to search for novel rare VKORC1 alleles. METHODS: A total of 148 patients were followed for 6 months and analyzed for VKORC1 and CYP2C9 gene variants. Analysis of variance and multiple linear regression analysis were used to study the contribution of each genetic factor to MWWD requirement. RESULTS: The complete sequencing of the VKORC1 coding region did not reveal the presence of exonic variants, while two common noncoding SNPs were highly associated: the T allele of VKORC1 1173C>T SNP (tag-SNP of H1-H2 haplotypes) is highly associated with low MWWD (p < 0.0001), while the A allele of VKORC1 3730G>A SNP (tag-SNP of H9 haplotype) is associated with high MWWD (p = 0.001). Also, CYP2C9*2 (Arg144Cys) and CYP2C9*3 (Ile359Leu) variant alleles were significantly associated with low MWWD (p = 0.003 and 0.027, respectively). According to a multiple linear regression model including, besides VKORC1 and CYP2C9 SNPs, also age and weight, this percentage reaches 56% (gender is not significant). DISCUSSION: Our results clearly indicate VKORC1 as the gene with the largest contribution to MWWD. Analyzing only one tag SNP of VKORC1 gene (1173C>T), it is possible to foresee 20% of the total variability. Our results may contribute to give useful indications for clinicians especially in the initiation of therapy so as to avoid the risk of adverse events.

Multidimensional flow cytometry for detection of minimal residual disease in acute myeloid leukemia.

The term minimal residual disease (MRD) describes the situation in which, after chemotherapy for acute leukemia (AL), a morphologically normal bone marrow (BM) can still harbor a relevant amount of residual malignant cells. Several techniques are now amenable to investigate MRD, and all together they have designated a new era in which a re-definition of the current criteria of complete remission (CR) is required. Depending upon the measured level of MRD we can distinguish a variety of clinical situations ranging from a potentially cured disease to short-term remission. In the context of this spectrum of conditions there would be room for different therapeutic strategies ranging from no further therapy to pre-emptive therapy to treat early relapses (immunologic and/or molecular relapses). This review will focus on the state of art of MRD detection in acute myeloid leukemia (AML) using multidimensional flow cytometry (MFC), and will cover the laboratory and clinical aspects of this approach.