Brief report: High incidence of peridiagnosis thromboembolic events in patients with BRAF-mutant lung cancer.

INTRODUCTION: We aimed to determine if advanced BRAF-mutant NSCLC has a higher thromboembolic events (TEE) rate than the expected. METHODS: Between 2008 and 2021, 182 patients with BRAF-mutant advanced NSCLC (BRAF V600E, n = 70; BRAF non-V600E, n = 112) were retrospectively identified from 18 centers in Spain. Patients received chemotherapy (n = 147), immunotherapy (n = 69), targeted therapy (n = 42), and immunotherapy + chemotherapy (n = 26). RESULTS: Incidence rate of TEE was 26.4 % (95%CI: 19.9 %-32.9 %). A total of 72 TEE were documented among 48 patients, as 18 patients (37.5 %) developed more than one event. Median time to TEE onset was 2 months, 69 % of TEE occurred in the peridiagnostic period (+/- 90 days from cancer diagnosis), and in 16 pts. (33 %) TEE was the form of lung cancer presentation. Although most TEE were only venous (82 %; PE, n = 33; DVT, n = 16), arterial events were reported in 31 % and occurred earlier, or TEE presented in atypical locations (13.9 %). TEE were related to high hospitalization rate (59 %), recurrence (23 %), and mortality (10.4 %) despite appropriate anticoagulant/antiaggregant treatment. Median OS in patients without-TEE was 19.4 months (95%CI: 4.6-34.1), and significantly shorter in patients with arterial-TEE vs venous-TEE vs both of them: 9.9 months (95%CI: 0-23.5) vs 41.7 months (95%CI: 11.3-72.2 m) vs 2.7 months (95%CI: 2.1-3.3), p = 0.001. Neither clinical or molecular features (BRAF V600E/non-V600E), nor cancer treatment was associated to TEE occurrence. Khorana score underperformed to predict thrombosis at cancer diagnosis, as only 19.2 % of patients were classified as high-risk. CONCLUSIONS: Thrombotic events represent a new clinical feature of BRAF-mutant lung cancer. Patients with almost a 30 % incidence of TEE should be offered systematic anticoagulation.

Evaluation of acquired and hereditary risk factors for the development of thromboembolism in patients with systemic lupus erythematosus.

Although the contribution of antiphospholipid antibodies (aPL) to thrombolembolism in systemic lupus erythematosus (SLE) is well known, there is not enough data on the contribution of various hereditary thrombophilic factors. In this study, we aimed to determine acquired and hereditary thrombophilic factors in adult patients with SLE. A total of 93 SLE patients (87 women and 6 men) were included. Data on clinical, demographic and laboratory characteristics, and disease activity scores (SLEDAI) of the patients were evaluated. The patients were analyzed with a screen, including lupus anticoagulant, anticardiolipin antibodies (aCL), antithrombin III, protein C, protein S, and homocysteine levels; factor V Leiden ( FVL ), methylenetetrahydrofolate reductase ( MTHFR ) and prothrombin G20210A gene mutations. A total of 23 thromboembolic events were reported in 17 (18.3%) of the patients. The frequency of pregnancy complications and SLEDAI scores were significantly higher in SLE patients who had a thromboembolism event ( P  < 0.05). Thromboembolism was detected in 12 (32.4%) of 37 patients with positive aPL antibody and 5 (8.9%) of 56 patients with negative aPL antibody ( P  = 0.006). In addition, thromboembolism developed in 11 (32.3%) of 34 lupus anticoagulant-positive patients and 6 (10.1%) of 59 lupus anticoagulant-negative patients ( P  = 0.012). Moreover, protein C levels were significantly lower in patients who developed thromboembolism ( P  < 0.05). Patients with and without thromboembolism were similar in terms of genetic thrombophilia factors ( MTHFR A1298C, MTHFR C677T, FVL and Prothrombin G20210A ) ( P  > 0.05). In conclusion, in the current study, some acquired (aPL, lupus anticoagulant and cCL IGG) and hereditary (protein C deficiency) thrombophilic factors were shown to be associated with the development of thrombosis in SLE patients. However, the effect of other hereditary factors on the development of thromboembolism could not be demonstrated. According to the data of this study, genetic screening seems inappropriate in terms of the risk of thromboembolism in patients with SLE.

Cumulative Incidence of Thromboembolism and Prognostic Impact of Stroke in BRAF V600E-mutant Non-small-cell Lung Cancer.

BACKGROUND/AIM: Cancer and ischemic stroke are closely associated. Thromboembolism susceptibility in lung cancer may differ depending on oncogenic alterations. However, the clinical characteristics of thromboembolism in patients with BRAF-mutant non-small-cell lung cancer remain unknown. Thus, this study aimed to evaluate the cumulative incidence of thromboembolism in this population and describe such cases in detail. PATIENTS AND METHODS: We retrospectively investigated consecutive patients with BRAF V600E-mutant non-small-cell lung cancer. Cumulative incidence was calculated using a competing risk analysis. RESULTS: Of 10 patients with BRAF-V600E mutant lung cancer, five developed a total of seven thromboembolic events, showing a 1-year cumulative incidence of 43% (95% confidence interval=11-72%). These events consisted of four cancer-related stroke (CRS) events and three venous events including deep vein thrombosis or pulmonary embolism. Of note, most of the early thrombotic events were CRS. Two patients with CRS had multiple brain infarctions during anticancer drug therapy, characterized by high D-dimer levels, resulting in short-term mortality (13 and 22 days after stroke onset). CONCLUSION: A substantial proportion of patients with BRAF V600E-mutant lung cancer experienced thromboembolism during their disease course. CRS of undetermined source may predict a worse prognosis in this population.

Risk of thromboembolism in non-small-cell lung cancers patients with different oncogenic drivers, including ROS1, ALK, and EGFR mutations.

BACKGROUND: Anaplastic lymphoma kinase-positive (ALK+) and ROS proto-oncogene 1 (ROS1)-positive (ROS1+) lung cancers have been reported to be associated with an elevated risk of thromboembolic events. This study aimed to assess the long-term risk of developing thromboembolism (TE) in ROS1+ lung cancer and to compare it with other oncogenic drivers in the Asian population. MATERIALS AND METHODS: We retrospectively enrolled a cohort of ROS1+ lung adenocarcinoma in a medical center in Taiwan and a comparison cohort of ALK+ and epidermal growth factor receptor-positive (EGFR+) lung cancers. Venous and arterial TEs were identified throughout the cancer course, and the incidence rate was calculated. RESULTS: We enrolled 44 ROS1+, 98 ALK+, and 168 EGFR+ non-small-cell lung cancer (NSCLC) patients. A total of 11 (25%), 36 (36.7%), and 38 (22.6%) patients in the ROS1, ALK, and EGFR cohorts, respectively, were diagnosed with thromboembolic events throughout the follow-up course of the disease (P = 0.042). The incidence rates were 99.0, 91.9, and 82.5 events per 1000 person-years for the ROS1, ALK, and EGFR cohorts, respectively. The majority of thrombosis events in the ROS1 (91.6%) and ALK (85.4%) cohorts were venous. On the contrary, 43.2% of thromboembolic events were arterial in the EGFR cohort. A higher proportion of thromboembolic events were noted during cancer diagnosis in the ROS1 cohort (36.3%) than in the ALK (16.7%) and EGFR (10.5%) cohorts. The stage was the only clinical variable associated with thromboembolic risk. There was a significant difference in survival between patients with and without TE in the EGFR cohort, but not in the ALK and ROS1 cohorts. CONCLUSIONS: Although ROS1+ and ALK+ NSCLCs had a higher cumulative incidence of TE than EGFR+ NSCLC, the person-year incidence rates were similar among the three groups. EGFR-mutated NSCLC had more arterial events. Nevertheless, ALK+ lung cancer had higher venous events than EGFR-mutated lung cancer.

Common genetic driver mutation in NSCLC and their association with thromboembolic events: A retrospective study.

This retrospective study aimed to estimate the incidence, risk factors of thromboembolism events (TEs) in non-small cell lung cancer patients harboring common gene mutation, and evaluate a genetic link between oncogenes and the risk of TEs in Asian patients with NSCLC. METHODS: Univariate and multivariate Cox's proportional hazards regression models were used to identify the strongest predictors of TE development and evaluate the risk of TE in patients with different gene statuses of NSCLC patients. RESULTS: In univariate and multivariate COX analysis, patient with squamous cell carcinoma (HR 3.01, 95% CI: [1.06,8.56]; p = 0.039), multi-site metastases (HR: 2.72; 95% CI: [1.08,6.92]; p = 0.032) or high white blood cell (WBC) (HR 3.24, 95% CI: [1.46,7.22]; p = 0.004), less hemoglobin (HGB) (HR 4.89, 95% CI: [1.90,12.64]; p = 0.001), are at higher risk of thrombosis. At the molecular level, ROS and ALK rearrangement is highly associated with TE development, with HR of 4.04 (95%CI: [1.54,10.58]; p = 0.005) and HR of 3.57 (95% CI: [1.01,12.66]; p = 0.049) in univariate analysis, and even higher in multivariate analysis. EGFR mutations seem to be a protective factor against TE in univariate analyses (HR:0.28, 95%CI [0.12,0.65], p = 0.003) but are not statistically significant in the multivariate model. No correlation between KRAS mutations and TE events in both models. Besides, a numerically higher cumulative incidence of thrombosis event was observed in patients who used TKI (HR 1.473; 95% CI: [0.682, 3.181]; p = 0.32). CONCLUSION: Our study demonstrated that driver gene mutation may increase the risk of thrombosis in non-small cell lung cancer patients. The presence of ALK/ROS rearrangements in our study is associated with an approximately threefold to fourfold increase in thrombosis risk in NSCLC patients. For advanced-stage patients who used TKI, an increased incidence of thrombosis risk and shorter follow-up were observed.

Incidence, characteristics and risk factors of thromboembolic events in East Asian patients with BCR-ABL1 negative myeloproliferative neoplasms.

The vascular complications have been a major cause of morbidity and mortality among all subtypes of BCR-ABL1 negative myeloproliferative neoplasms (MPN), but the ethnicity-specific data was limited. We therefore conducted a multi-center retrospective, longitudinal cohort study to evaluate the incidence, characteristics and risk factors of thromboembolic events of MPN patients. Of 256 patients, 27.3% experienced thromboembolic events, majority of which occurred before or within 12 months of MPN diagnosis. The multivariable Cox proportional analyses identified leukocytosis (HR 2.67, 95% CI 1.36-5.24, q = 0.004) and history of thrombosis (HR 9.68, 95% CI 2.00-46.88, q = 0.005) as the risk factors for thromboembolism. In subgroup analysis of polycythemia vera and hemoglobin concentration (HR 1.97, 95% CI 1.28-3.04, q = 0.002) appeared to be a significant risk factor of thrombosis, along with age and thrombosis history. In essential thrombocythemia, severity of the established IPSET score was closely correlated with the frequency of thromboembolic events. In primary myelofibrosis, history of thrombosis was associated with thrombosis events (HR 13.85, 95% CI 1.2-159.5, q = 0.035). Overall survival was worse in patients who experienced thromboembolic events. Our study highlighted the importance of recognizing high risk patients and implementing personalized intervention.

Extensive Thromboembolism in a Young Male with Asymptomatic COVID-19 Infection and Heterozygous Factor V Leiden Mutation.

In this case report we present a previously healthy 21-year-old male with extensive thromboembolism in the setting of asymptomatic COVID-19 infection and heterozygous factor V Leiden mutation with no additional thrombophilic risk factors.

Clinical Impact of Heritable Thrombophilia on Neonatal-Onset Thromboembolism: A Nationwide Study in Japan.

OBJECTIVE: To clarify the incidence and genetic risk of neonatal-thromboembolism, we conducted a nationwide study exploring the impact of thrombophilia on neonatal-thromboembolism in Japan. STUDY DESIGN: A questionnaire survey was conducted for perinatal centers in Japan, focusing on the clinical expression, genotype, treatment, and outcome of patients who developed thromboembolism within 28 days of birth from 2014 to 2018. RESULTS: The estimated incidence of neonatal-thromboembolism was 0.39 cases per 10 000 live births. Intracranial lesions and purpura fulminans occurred in 66 and 5 of 77 patients, respectively. Fifty-eight (75.3%) infants presented within 3 days after birth. Four (5.2%) died, and 14 (18.2%) survived with disability. At the diagnosis, <20% plasma activity of protein C was noted in 16 infants, protein S (in 2), and antithrombin (in 1). Thirteen genetic tests identified 4 biallelic and 5 monoallelic protein C-variants but no protein S- or antithrombin-variants. Protein C-variants had purpura fulminans (P < .01), ocular bleeding (P < .01), positive-family history (P = .01), and death or disability (P = .03) more frequently than others. Protein C-variants were independently associated with disability (OR 5.74, 95% CI 1.16-28.4, P = .03) but not death. Four biallelic variants had serious thrombotic complications of neurologic disability, blindness, and/or amputation. Three monoallelic variants survived without complications. The only protein C-variant death was an extremely preterm heterozygote infant. CONCLUSIONS: Monoallelic protein C-variants had a higher incidence of neonatal-thromboembolism than biallelic variants. Thrombophilia genetic testing should be performed in the setting of neonatal-thromboembolism and low protein C to identify the underlying genetic defect.

Cell landscape atlas for patients with chronic thromboembolic pulmonary hypertension after pulmonary endarterectomy constructed using single-cell RNA sequencing.

This study aimed to construct an atlas of the cell landscape and comprehensively characterize the cellular repertoire of the pulmonary endarterectomized tissues of patients with chronic thromboembolic pulmonary hypertension (CTEPH). Five pulmonary endarterectomized tissues were collected. 10× Genomics single-cell RNA sequencing was performed, followed by the identification of cluster marker genes and cell types. Gene Ontology (GO) enrichment analysis was conducted. Seventeen cell clusters were characterized, corresponding to 10,518 marker genes, and then classified into eight cell types, including fibroblast/smooth muscle cell, endothelial cell, T cell/NK cell, macrophage, mast cell, cysteine rich secretory protein LCCL domain containing 2 (CRISPLD2)+ cell, cancer stem cell, and undefined. The specific marker genes of fibroblast/smooth muscle cell, endothelial cell, T cell/NK cell, macrophage, mast cell, and cancer stem cell were significantly enriched for multiple functions associated with muscle cell migration, endothelial cell migration, T cell activation, neutrophil activation, erythrocyte homeostasis, and tissue remodeling, respectively. No functions were significantly enriched for the marker gene of CRISPLD2+ cell. Our study, for the first time, provides an atlas of the cell landscape of the pulmonary endarterectomized tissues of CTEPH patients at single-cell resolution, which may serve as a valuable resource for further elucidation of disease pathophysiology.

Pharmacogenetics of Bleeding and Thromboembolic Events in Direct Oral Anticoagulant Users.

This study aimed to analyze associations between genetic variants and the occurrence of clinical outcomes in dabigatran, apixaban, and rivaroxaban users. This was a retrospective real-world study linking genotype data of three Finnish biobanks with national register data on drug dispensations and healthcare encounters. We investigated several single-nucleotide variants (SNVs) in the ABCG2, ABCB1, CES1, and CYP3A5 genes potentially associated with bleeding or thromboembolic events in direct oral anticoagulant (DOAC) users based on earlier research. We used Cox regression models to compare the incidence of clinical outcomes between carriers and noncarriers of the SNVs or haplotypes. In total, 1,806 patients on apixaban, dabigatran, or rivaroxaban were studied. The ABCB1 c.3435C>T (p.Ile1145=, rs1045642) SNV (hazard ratio (HR) 0.42, 95% confidence interval (CI), 0.18-0.98, P = 0.044) and 1236T-2677T-3435T (rs1128503-rs2032582-rs1045642) haplotype (HR 0.44, 95% CI, 0.20-0.95, P = 0.036) were associated with a reduced risk for thromboembolic outcomes, and the 1236C-2677G-3435C (HR 2.55, 95% CI, 1.03-6.36, P = 0.044) and 1236T-2677G-3435C (HR 5.88, 95% CI, 2.35-14.72, P < 0.001) haplotypes with an increased risk for thromboembolic outcomes in rivaroxaban users. The ABCB1 c.2482-2236G>A (rs4148738) SNV associated with a lower risk for bleeding events (HR 0.37, 95% CI, 0.16-0.89, P = 0.025) in apixaban users. ABCB1 variants are potential factors affecting thromboembolic events in rivaroxaban users and bleeding events in apixaban users. Studies with larger numbers of patients are warranted for comprehensive assessment of the pharmacogenetic associations of DOACs and their relevance for clinical practice.

Expression of miR-93-5p as a Potential Predictor of the Severity of Chronic Thromboembolic Pulmonary Hypertension.

BACKGROUND: MicroRNAs (miRNAs) play an important role in the pathogenesis of chronic thromboembolic pulmonary hypertension (CTEPH). However, the potential correlation between miRNA expression and the severity of CTEPH remains unclear. Our previous study indicated that miRNAs hsa-let-7b-3p, hsa-miR-17-5p, hsa-miR-106b-5p, hsa-miR-3202, hsa-miR-665, and hsa-miR-93-5p are closely involved in CTEPH. This study assessed the associations between the expression levels of these miRNAs and clinical parameters in CTEPH patients. METHODS: A total of eight CTEPH patients and eight healthy adults as a reference group were included, and clinical data including total protein (TP), albumin (Alb), lactate dehydrogenase (LDH), hydroxybutyrate dehydrogenase (HBDH), uric acid (UA), and N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels were collected. Right heart catheterization was conducted to obtain hemodynamic data including cardiac index (CI). The expression levels of let-7b-3p, miR-17-5p, miR-106b-5p, miR-3202, miR-665, and miR-93-5p were measured by quantitative real-time PCR (qPCR). Correlation analysis was applied to estimate the associations between miRNA expression levels and clinical parameters in CTEPH patients. RESULTS: Serum TP and Alb levels were decreased, while LDH, HBDH, and UA levels were increased in CTEPH patients compared with the reference group (P < 0.05). miR-3202 and miR-665 were upregulated, whereas let-7b-3p, miR-17-5p, miR-106b-5p, and miR-93-5p were downregulated in CTEPH patients relative to the reference group (P < 0.05). miR-93-5p expression was positively correlated with NT-proBNP level and negatively correlated with CI (P < 0.05). Moreover, let-7b-3p tended to be positively correlated with mean pulmonary arterial pressure. CONCLUSIONS: miR-93-5p expression was associated with the severity of CTEPH and could act as a potential predictor of high-risk CTEPH.

The Inflammatory Profile of CTEPH-Derived Endothelial Cells Is a Possible Driver of Disease Progression.

Chronic thromboembolic pulmonary hypertension (CTEPH) is a form of pulmonary hypertension characterized by the presence of fibrotic intraluminal thrombi and causing obliteration of the pulmonary arteries. Although both endothelial cell (EC) dysfunction and inflammation are linked to CTEPH pathogenesis, regulation of the basal inflammatory response of ECs in CTEPH is not fully understood. Therefore, in the present study, we investigated the role of the nuclear factor (NF)-κB pro-inflammatory signaling pathway in ECs in CTEPH under basal conditions. Basal mRNA levels of interleukin (IL)-8, IL-1ß, monocyte chemoattractant protein-1 (MCP-1), C-C motif chemokine ligand 5 (CCL5), and vascular cell adhesion molecule-1 (VCAM-1) were upregulated in CTEPH-ECs compared to the control cells. To assess the involvement of NF-κB signaling in basal inflammatory activation, CTEPH-ECs were incubated with the NF-κB inhibitor Bay 11-7085. The increase in pro-inflammatory cytokines was abolished when cells were incubated with the NF-κB inhibitor. To determine if NF-κB was indeed activated, we stained pulmonary endarterectomy (PEA) specimens from CTEPH patients and ECs isolated from PEA specimens for phospho-NF-κB-P65 and found that especially the vessels within the thrombus and CTEPH-ECs are positive for phospho-NF-κB-P65. In summary, we show that CTEPH-ECs have a pro-inflammatory status under basal conditions, and blocking NF-κB signaling reduces the production of inflammatory factors in CTEPH-ECs. Therefore, our results show that the increased basal pro-inflammatory status of CTEPH-ECs is, at least partially, regulated through activation of NF-κB signaling and potentially contributes to the pathophysiology and progression of CTEPH.

Association of Genetically Predicted Serum Estradiol With Risk of Thromboembolism in Men: A Mendelian Randomization Study.

CONTEXT: An association was recently reported between genetic markers related to high testosterone and increased risk of thromboembolism in men, but a possible causal role of estradiol for risk of thromboembolism in men remains unknown. OBJECTIVE: This work aimed to determine whether endogenous estradiol has a causal role in thromboembolism in men. METHODS: A 2-sample mendelian randomization study using gene-based genetic instruments assessed the association between endogenous estradiol genetically predicted by 22 variants in the aromatase CYP19A1 gene region and the risk of thromboembolism (5815 cases) in 170 593 unrelated men of White ancestry in the UK Biobank. The main outcome measure included thromboembolism based on self-reports, hospital episodes, and death. RESULTS: Endogenous estradiol genetically predicted by variants in the CYP19A1 gene region was inversely associated with the risk of thromboembolism (odds ratio per SD increase in estradiol 0.74; 95% CI, 0.62-0.90). In contrast, genetic variants in the JMJD1C gene, used as a predictor of high endogenous testosterone, were associated with an increased risk of thromboembolism (odds ratio per SD increase in testosterone 1.39; 95% CI, 1.12-1.72). Subsequent explorative analyses evaluating potential repercussions of thromboembolism revealed that endogenous estradiol genetically predicted by variants in the CYP19A1 gene region was inversely associated with the risk of ischemic stroke (0.68; 95% CI, 0.49-0.95) but not myocardial infarction (0.97; 95% CI, 0.84-1.13). CONCLUSION: Genetically predicted estradiol was inversely associated with the risk of thromboembolism and ischemic stroke in men. The ratio between testosterone and estradiol, determined by CYP19A1 activity, may contribute to the overall impact of sex steroids on thromboembolism in men.

Prevalence and Effect of Genetic Risk of Thromboembolic Disease in Inflammatory Bowel Disease.

BACKGROUND AND AIMS: The largest cause of mortality in patients with inflammatory bowel disease (IBD) remains thromboembolic disease (TED). Recent reports have demonstrated that both monogenic and polygenic factors contribute to TED and 10% of healthy subjects are genetically at high risk for TED. Our aim was to utilize whole-exome sequencing and genome-wide genotyping to determine the proportion of IBD patients genetically at risk for TED and investigate the effect of genetic risk of TED in IBD. METHODS: The TED polygenic risk score was calculated from genome-wide genotyping. Thrombophilia pathogenic variants were extracted from whole-exome sequencing. In total, 792 IBD patients had both whole-exome sequencing and genotyping data. We defined patients at genetically high risk for TED if they had a high TED polygenic risk score or carried at least 1 thrombophilia pathogenic variant. RESULTS: We identified 122 of 792 IBD patients (15.4%) as genetically high risk for TED. Among 715 of 792 subjects whose documented TED status were available, 63 of the 715 patients (8.8%) had TED events. Genetic TED risk was significantly associated with increased TED event (odds ratio, 2.5; P = .0036). In addition, we confirmed an additive effect of monogenic and polygenic risk on TED (P = .0048). Patients with high TED genetic risk more frequently had thrombosis at multiple sites (78% vs 42%, odds ratio, 3.96; P = .048). CONCLUSIONS: Genetic risk (both poly- and monogenic) was significantly associated with TED history. Our results suggest that genetic traits identify approximately 1 in 7 patients with IBD who will experience 2.5-fold or greater risk for TED.

High risk of thrombosis in patients with advanced lung cancer harboring rearrangements in ROS1.

INTRODUCTION: Based on the high incidence of thromboembolic events (TEs) observed in lung adenocarcinomas with ALK translocations and taking into account the biological proximity of ROS1 and ALK, we conducted a retrospective analysis of patients with advanced lung carcinoma carrying rearrangements in ROS1 from 23 centres in Spain and one centre in Portugal. METHODS: The main objective of the study was to analyse the incidence of TE in this population, looking for predictive risk factors, and its impact on overall survival. RESULTS: A total of 58 patients were included. The incidence of TEs throughout the disease was 46.6% (n = 27) with a median follow-up of 19 months (range: 1-78 months) and a median overall survival of 52 months in the total population and 50 months for the patients presenting TEs, with a hazards ratio of 1.12 (95% confidence interval: 0.47-2.65) p = 0.78. The majority of the events were venous (n = 24; 89%) and occurred in the ambulatory setting (n = 18; 67%). Almost half of the patients (n = 13; 48%) presented the TE in the peri-diagnostic period. CONCLUSIONS: The high incidence of thrombosis, especially during the cancer diagnosis process, requires special attention from a clinician. Despite the limitations of such a small descriptive study, its results are in accordance with previously reported data. It would be important to design prospective studies of antithrombotic prophylaxis in this population because of their possible impact in reducing the risk of TEs.

PROC Promoter Single Nucleotide Polymorphisms Associated With Low Protein C Activity But Not Increased Risk of Thromboembolism in Pediatric Population.

Protein C (PC) deficiency, caused by mutations of the PROC gene, is a common inherited risk factor of thromboembolism (TE) among Thai people. This study aimed to investigate the association of 3 single nucleotide polymorphisms (SNPs; -1654 C/T, -1641 A/G, -1461A/T) at the PROC promoter region with PC activity and the risk of developing TE. A total of 216 patient s with TE, diagnosed at aged 0 to 20 years, and 102 healthy adults were enrolled. The SNPs were identified by Sanger sequencing. Protein C activity was measured using an automated functional clotting assay. Linear and logistic regression analyses were used to determine the association of SNPs with PC activity and the risk of TE. Patients and controls with homozygous TAA (119.6% ± 26.1%) and CGT haplotypes (102.7% ± 22.6%) had significantly lower PC activity than those with a homozygous CAA haplotype (140.4% ± 44.9%); P = .027 and .016, respectively. However, none of these haplotypes increased the risk of TE. This study suggested that the 3 PROC promoter SNPs were shown to be associated with lower PC activity but did not increase the risk of TE.

Effect of ABO Blood Groups on the Response to Warfarin.

BACKGROUND: Numerous studies have demonstrated that patients with non-O blood groups have a higher risk for venous thromboembolism than those with the O blood group. However, the effect of ABO blood groups on warfarin dose requirements in patients receiving anticoagulation in the Chinese Han population remains unknown. This study aimed to investigate the influence of ABO blood groups on warfarin dose requirements in a Chinese Han population. MATERIAL AND METHODS: A retrospective study was conducted in the First Affiliated Hospital of Shantou University Medical College in South China. Three hundred and fifty-eight patients with a confirmed diagnosis of deep vein thrombosis or atrial fibrillation were included. The frequency of blood groups and warfarin dose requirements were determined. RESULTS: Of 358 patients with deep vein thrombosis or atrial fibrillation, 111 patients had blood group A (31.01%), 104 patients had blood group B (29.05%), 20 patients had blood group AB (5.59%) and 123 patients had blood group O (34.36%). The patients in the O blood group had lower warfarin dose requirements than those in the A, B and AB blood groups. CONCLUSIONS: Our study showed that patients with non-O blood groups require higher doses of warfarin.

Genotype-guided warfarin therapy: Still of only questionable value two decades on.

WHAT IS KNOWN AND OBJECTIVE: Despite an apparently sound pharmacological basis, clinical studies of genotype-guided warfarin dosing have yielded mixed and conflicting results, leading to reluctance in its clinical implementation. The objective of this critique is to re-evaluate key warfarin pharmacogenetic studies with a view to explaining why this may be so. METHODS: Major widely-cited warfarin pharmacogenetic studies as well as recent meta-analyses were identified and a critical analysis of these was undertaken to identify factors that may account for poor clinical implementation of pre-treatment genotyping. RESULTS AND DISCUSSION: Critical examination of major warfarin pharmacogenetic studies identified a number of methodological concerns such as marked variations in study designs with different variously-defined measures of outcome. Genotype testing involved only a limited number of CYP2C9/VKORC1 alleles. Claims of benefits of genotyping are based almost exclusively on INR-related parameters which are known to be highly time-labile and of limited value in predicting clinical risk or benefit. This is evidenced by lack of any significant effect of genotyping on rates of bleeding or thromboembolic events. Neither have the effects of potential phenoconversion or medication non-adherence in study populations been adequately investigated. Although the effect of ethnicity/race is now better characterised, studies lack the power to determine whether any benefits claimed are indication-sensitive. WHAT IS NEW AND CONCLUSION: Since 60% of inter-individual variability in warfarin dose/response is due to other factors (many of which are non-genetic), expectations of eliminating this variability simply by CYP2C9/VKORC1 genotyping are over-optimistic and efforts cost-ineffective. Real-world studies have not always corroborated trials-based claims of clinical benefit. It is time to consider redirecting scarce resources away from the study of warfarin pharmacogenetics to pharmacogenetic research of potentially greater clinical relevance.