Cost-Utility of All-Oral Direct-Acting Antiviral Regimens for the Treatment of Genotype 1 Chronic Hepatitis C Virus-Infected Patients in Hong Kong.

BACKGROUND: Direct-acting antivirals (DAAs) are entering the hepatitis C virus (HCV) treatment landscape in Hong Kong, prompting the need for cost-effectiveness evaluations of these interventions to enable optimal use of healthcare resources. AIMS: This study aimed to compare the cost-effectiveness of DAAs to standard-of-care pegylated interferon plus ribavirin (RBV) in treatment-naïve patients without significant liver fibrosis and to compare different DAAs in patients who are treatment-experienced and/or have advanced liver disease. METHODS: A Markov model was constructed to evaluate cost-effectiveness over a lifetime time horizon from the payer perspective. The target population was treatment-naïve and treatment-experienced HCV genotype 1 patients, stratified by degree of liver fibrosis. The model consists of 16 health states encompassing METAVIR fibrosis score (F0-F4), treatment success or failure, decompensated cirrhosis, hepatocellular carcinoma, liver transplant, and liver-related death. The proportions of patients achieving sustained virologic response were obtained from clinical trials. Other inputs were obtained from published and local data. The primary outcome was incremental cost-utility ratio for each DAA versus pegylated interferon + ribavirin and among different DAAs. RESULTS: In treatment-naïve F0-2 HCV patients, all DAAs were cost-effective in genotype 1a and daclatasvir + asunaprevir, elbasvir/grazoprevir, ledipasvir/sofosbuvir, and glecaprevir/pibrentasvir were cost-effective compared to pegylated interferon + ribavirin in genotype 1b. In genotypes 1a and 1b, treatment-experienced patients, and F3-4 patients, elbasvir/grazoprevir was the least costly DAA and economically dominant over most other DAAs. CONCLUSIONS: DAAs can be a cost-effective option for the treatment of genotype 1 HCV patients in Hong Kong, and elbasvir/grazoprevir is cost-effective.

Cost-effectiveness analysis of pembrolizumab compared to standard of care as first line treatment for patients with advanced melanoma in Hong Kong.

BACKGROUND: Pembrolizumab has been shown to improve overall survival (OS) and progression free survival (PFS) compared to ipilimumab in patients with ipilimumab-naïve advanced melanoma; however, there are no published data on the cost-effectiveness for pembrolizumab compared to standard-of-care treatments currently used in Hong Kong for advanced melanoma. METHODS: A partitioned-survival model based on data from a recent randomized phase 3 study (KEYNOTE-006) and meta-analysis was used to derive time in PFS, OS, and post-progression survival for pembrolizumab and chemotherapy, such as dacarbazine (DTIC), temozolomide (TMZ), and the paclitaxel-carboplatin combination (PC). A combination of clinical trial data, published data, results of meta-analysis, and melanoma registry data was used to extrapolate PFS and OS curves. The base-case time horizon for the model was 30 years with costs and health outcomes discounted at a rate of 5% per year. Individual patient level data on utilities and frequencies of adverse events were obtained from the final analysis of KEYNOTE-006 (cut-off date: 3-Dec-15) for pembrolizumab. Cost data included drug acquisition, treatment administration, adverse event management, and clinical management of advanced melanoma. The distribution of patient weight from the Hong Kong population was applied to calculate the drug costs. Analyses were performed from a payer's perspective. The incremental cost effectiveness ratio (ICER) expressed as cost in US Dollars (USD) per quality-adjusted life years (QALYs) was the main outcome. RESULTS: In base-case scenario, the ICER for pembrolizumab as a first-line treatment for advanced melanoma was USD49,232 compared to DTIC, with the ICER values lower than cost-effectiveness threshold in Hong Kong. Results comparing pembrolizumab to TMZ and to PC were similar to that when compared to DTIC. Probability sensitivity analyses showed that 99% of the simulated ICERs were below three times the Gross Domestic Product (GDP) per capita for Hong Kong (currently at $119,274//QALY threshold). In a scenario analysis comparing pembrolizumab with ipilimumab, the estimated ICER was USD8,904. CONCLUSIONS: Pembrolizumab is cost-effective relative to chemotherapy (DTIC, TMZ and PC), and highly-cost-effective compared to ipilimumab, for the first-line treatment of advanced melanoma in Hong Kong.

Cost Effectiveness of PD-L1-Based Test-and-Treat Strategy with Pembrolizumab as the First-Line Treatment for Metastatic NSCLC in Hong Kong.

BACKGROUND: Pembrolizumab, a monoclonal antibody against programmed death ligand 1 (PD-L1), is approved by several regulatory agencies for first-line treatment of metastatic non-small-cell lung cancer (NSCLC) with a PD-L1 tumor proportion score (TPS) ≥ 50% and no epidermal growth factor receptor (EGFR) or anaplastic lymphoma kinase genomic tumor aberrations. This study was conducted from the perspective of the Hospital Authority in Hong Kong and aimed to evaluate the cost effectiveness of a biomarker (PD-L1) test-and-treat strategy (BTS), in which patients with a TPS ≥ 50% received pembrolizumab and other patients received platinum doublet chemotherapy versus all patients receiving platinum doublet chemotherapy. METHODS: The model used a partitioned survival approach to estimate the incremental cost-effectiveness ratio (ICER) expressed as the cost per quality-adjusted life-year (QALY) gained. The clinical efficacy, utility and safety data were derived from the KN024 trial. Costs and health outcomes were projected over a 10-year time horizon and discounted at 3% per year. Costs for drug acquisition, PD-L1 testing, drug administration and disease management were used. Sensitivity analyses were conducted to evaluate the robustness of results. RESULTS: The BTS approach led to an increase of 0.29 QALYs at an additional cost of Hong Kong dollars (HK$) 249,077 (US$31,933) compared with platinum doublet chemotherapy, resulting in an ICER of HK$865,189 (US$110,922) per QALY gained. This is lower than the World Health Organization cost-effectiveness threshold of three times the 2016 gross domestic product (GDP) per capita for Hong Kong of HK$1017,819 (US$130,490). Probabilistic sensitivity analyses showed a 59.4% chance that the ICER would be below this threshold. CONCLUSION: First-line treatment with pembrolizumab in a BTS to identify patients with NSCLC with PD-L1 TPS ≥ 50% can be considered cost effective in Hong Kong compared with platinum doublet chemotherapy based on a three-times GDP per capita threshold. However, local data on clinical efficacy and safety were not available to estimate overall survival (OS) and progression-free survival (PFS) specific to patients with NSCLC in Hong Kong. Further, uncertainty is inherent in the survival projections/extrapolation of PFS and OS beyond the trial period, and future research may help to further inform these parameters.

Low but not high frequency of intermittent hypoxia suppresses endothelium-dependent, oxidative stress-mediated contractions in carotid arteries of obese mice.

Obstructive sleep apnea is characterized by intermittent hypoxia (IH) during sleep and predisposes to endothelial dysfunction. Obesity is a major risk factor for the occurrence of sleep apnea. The present study compared the functional impact of low- (IH10; 10 hypoxic events/h) and high-frequency (IH60; 60 hypoxic events/h) IH for 4 wk on endothelial function in male C57BL/6 mice with or without high-fat (HF) diet-induced obesity. Mean arterial blood pressure (tail cuff method) was increased in obese mice after IH60 exposure, i.e., HF + IH60 group. The serum levels of the oxidative stress marker malondialdehyde were augmented in lean IH60 and HF groups, with a further increase in HF + IH60 but a reduction in HF + IH10 mice compared with the HF group. Vascular responsiveness was assessed as changes in isometric tension in isolated arteries. Relaxations to the endothelium-dependent vasodilator acetylcholine were impaired in HF + IH60 aortae. Endothelium-dependent contractions (EDC; response to acetylcholine in the presence of the nitric oxide synthase inhibitor l-NAME) in carotid arteries were augmented in the HF group, but this HF-induced augmentation was suppressed by low-frequency IH exposure. The addition of apocynin (antioxidant) reduced EDC in HF and HF + IH60 groups but not in HF + IH10 group. In conclusion, these findings suggest that exposure of obese mice to mild IH exerts preconditioning-like suppression of endothelium-dependent and oxidative stress-mediated contractions. When IH severity increases, this suppression diminishes and endothelial dysfunction accelerates. NEW & NOTEWORTHY The present study demonstrates, for the first time, that low-frequency intermittent hypoxia may exert a preconditioning-like suppression of oxidative stress-induced endothelium-dependent contractions in mice with diet-induced obesity. This relative suppression was diminished as intermittent hypoxia became more severe, and a deleterious effect on endothelial function emerged.

Low-Frequency Intermittent Hypoxia Promotes Subcutaneous Adipogenic Differentiation.

Obstructive sleep apnea (OSA), characterized by intermittent hypoxia (IH), is associated with obesity and metabolic disorders. The mass and function of adipose tissue are largely dependent on adipogenesis. The impact of low-frequency IH on adipogenesis is unknown. Sprague-Dawley rats were subjected to IH (4 min for 10% O2 and 2 min for 21% O2) or intermittent normoxia (IN) for 6 weeks. The degree of adipogenic differentiation was evaluated by adipogenic transcriptional factors, adipocyte-specific proteins, and oily droplet production in both subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT). Upregulation of proadipogenic markers (CEBPα, PPARγ, and FABP4) and downregulation of antiadipogenic markers CHOP in line with smaller size of adipocytes were found in IH-exposed SAT. In vitro experiments using human preadipocytes (HPAs) of subcutaneous lineage during differentiation phase, subjected to IH (1% O2 for 10 min and 21% O2 for 5 min; 5% CO2) or IN treatment, were done to investigate the insulin-like growth factor 1 receptor (IGF-1R)/Akt pathway in adipogenesis. IH promoted the accumulation of oily droplets and adipogenesis-associated markers. IGF-1R kinase inhibitor NVP-AEW541 attenuated the proadipogenic role in IH-exposed HPAs. In summary, relatively low frequency of IH may enhance adipogenesis preferentially in SAT.

Intermittent hypoxia induces NF-κB-dependent endothelial activation via adipocyte-derived mediators.

Aberrant release of adipocytokines from adipose tissues dysregulates cardiometabolic functions. The present study hypothesizes that chronic intermittent hypoxia (IH) present in obstructive sleep apnea leads to adipose tissue dysfunction, which in turn contributes to vascular pathogenesis. The effect of IH was evaluated in adipose depots and aortic tissues in lean rats in vivo. Furthermore, the cellular and molecular mechanisms underlying pathophysiological interactions between adipocytes and endothelial cells were investigated in vitro. The in vivo results showed that IH induced upregulation of IL-6 and monocyte chemoattractant protein-1 (MCP-1) in subcutaneous and periaortic adipose tissues and downregulated phosphorylation of endothelial nitric oxide synthase [eNOS (ser1177)] in the aorta with activation of Erk and p38 MAPK. In support, cultured adipocytes demonstrated IH-induced elevations of NADPH oxidase 4, phosphorylation of Erk, NF-κBp65, and inducible NOS (iNOS) and increased expression of IL-6 and MCP-1. Likewise, endothelial EA.hy926 (EA) cells exposed to IH showed eNOS (ser1177) and intracellular cGMP reduction, whereas MCP-1 and iNOS expression were upregulated. Treatment of EA cells with conditioned media derived from IH-exposed cultured adipocytes caused nuclear translocation of NF-κBp65 and elevation of MCP-1, which were prevented by addition of neutralizing IL-6 antibodies to the conditioned media. Recombinant IL-6 in addition to IH induced further MCP-1 release and iNOS protein expression in EA cells, which were prevented by pharmacological inhibition of Erk, p38, and NF-κB. These findings suggest that IH could induce adipose tissue inflammation, which may cross talk with endothelial cells via adipocyte-derived mediators such as IL-6, and promote NF-κB-dependent endothelial dysfunction.

A-FABP and oxidative stress underlie the impairment of endothelium-dependent relaxations to serotonin and the intima-medial thickening in the porcine coronary artery with regenerated endothelium.

Experiments were designed to determine the cause of the selective dysfunction of G(i) proteins, characterized by a reduced endothelium-dependent relaxation to serotonin (5-hydroxytryptamine), in coronary arteries lined with regenerated endothelial cells. Part of the endothelium of the left anterior descending coronary artery of female pigs was removed in vivo to induce regeneration. The animals were treated chronically with vehicle (control), apocynin (antioxidant), or BMS309403 (A-FABP inhibitor) for 28 days before functional examination and histological analysis of segments of coronary arteries with native or regenerated endothelium of the same hearts. Isometric tension was recorded in organ chambers and cumulative concentration-relaxation curves obtained in response to endothelium-dependent [serotonin (G(i) protein mediated activation of eNOS) and bradykinin (G(q) protein mediated activation of eNOS)] and independent [detaNONOate (cGMP-mediated), isoproterenol (cAMP-mediated)] vasodilators. The two inhibitors tested did not acutely affect relaxations of preparations with either native or regenerated endothelium. In the chronically treated groups, however, both apocynin and BMS309403 abolished the reduction in relaxation to serotonin in segments covered with regenerated endothelium and prevented the intima-medial thickening caused by endothelial regeneration, without affecting responses to bradykinin or endothelium-independent agonists (detaNONOate and isoproterenol). Thus, inhibition of either oxidative stress or A-FABP likely prevents both the selective dysfunction of G(i) protein mediated relaxation to serotonin and the neointimal thickening resulting from endothelial regeneration.

Cyclin-dependent kinase 5-mediated hyperphosphorylation of sirtuin-1 contributes to the development of endothelial senescence and atherosclerosis.

BACKGROUND: Endothelial senescence represents one of the major characteristics of vascular aging and promotes the development of atherosclerosis. Sirtuin-1 (SIRT1) is an NAD-dependent deacetylase possessing antiaging activities. During the occurrence of endothelial senescence, both the expression and activity of SIRT1 are downregulated. The present study was designed to investigate the molecular mechanisms contributing to the loss-of-SIRT1 function in senescent endothelial cells. METHODS AND RESULTS: After repetitive passages, primary cultures of porcine aortic endothelial cells exhibited a severe senescence phenotype. Western blotting revealed that phosphorylation of SIRT1 at serine 47 (S47) was significantly enhanced in senescent endothelial cells. S47 phosphorylation was stimulated by agents promoting senescence and attenuated by drugs with antisenescence properties. Mutation of S47 to nonphosphorable alanine (S47A) enhanced whereas replacing S47 with phospho-mimicking aspartic acid (S47D) abolished the antisenescent, growth-promoting, and LKB1-downregulating actions of SIRT1. Phosphorylation at S47 was critically involved in the nuclear retention of SIRT1 but abolished its association with the telomeric repeat-binding factor 2-interacting protein 1. Cyclin-dependent kinase 5 (CDK5) was identified as an SIRT1 kinase modulating S47 phosphorylation. Knockdown or inhibition of CDK5 reduced the number of senescent endothelial cells, promoted nuclear exportation of SIRT1, and attenuated the expression of inflammatory genes in porcine aortic endothelial cells. The truncated regulatory subunit of CDK5, P25, accumulated in senescent porcine aortic endothelial cells and atherosclerotic aortas. Long-term treatment with roscovitine, a CDK5 inhibitor, blocked the development of cellular senescence and atherosclerosis in aortas of hypercholesterolemic apolipoprotein E-deficient mice. CONCLUSION: CDK5-mediated hyperphosphorylation of SIRT1 facilitates the development of endothelial senescence and atherosclerosis.

Differential genomic changes caused by cholesterol- and PUFA-rich diets in regenerated porcine coronary endothelial cells.

Endothelial regeneration and dyslipidemia impair endothelium-dependent relaxation, while supplementation with fish oil (FO) prevents it. The genomic impact of different diets was compared in primary cultures derived from native and regenerated endothelial cells. Pigs were fed with high-cholesterol (CHL) or FO-rich diet. Partial in vivo removal of endothelium was performed to induce endothelial regeneration. Native and regenerated cells were harvested, cultured, and prepared for genomic (microarray experiments, real-time PCR) and proteomic (Western blotting) analysis. The analysis identified genomic changes induced by chronic CHL diet in native cultures resembling those induced by in vivo regeneration, as well as those that could be prevented by FO diet. At the protein level, the reduced and increased presences of endothelial nitric oxide synthase and F2, respectively, observed after regeneration combined with CHL diet were alleviated by FO. The comparison of the differential changes induced by regeneration in vivo in endothelial cells from both diet groups revealed a limited number of genes as the most likely contributors to reduction in endothelium-dependent relaxations in porcine coronary arteries lined with regenerated endothelium.

SIRT1 promotes proliferation and prevents senescence through targeting LKB1 in primary porcine aortic endothelial cells.

RATIONALE: Endothelial senescence causes endothelial dysfunction, promotes atherogenesis and contributes to age-related vascular disorders. SIRT1 is a conserved NAD(+)-dependent deacetylase possessing beneficial effects against aging-related diseases, despite that the detailed functional mechanisms are largely uncharacterized. OBJECTIVE: The present study is designed to evaluate the protective effects of SIRT1 on endothelial senescence and to elucidate the underlying mechanisms. METHODS AND RESULTS: An in vitro senescence model was established by prolonged culture of primary endothelial cells isolated from porcine aorta. The freshly isolated "young" cells gradually underwent senescence during 1 month of repetitive passages. Both mRNA and protein expressions of SIRT1 were progressively decreased. In contrast, the protein levels of LKB1, a serine/threonine kinase and tumor suppressor, and the phosphorylation of its downstream target AMPK(Thr172) were dramatically increased in senescent cells. Overexpression of LKB1 promoted cellular senescence and retarded endothelial proliferation, which could be blocked by increasing SIRT1 levels. Knocking down of SIRT1 induced senescence and elevated the protein levels of LKB1 and phosphorylated AMPK(Thr172). Regardless of the nutritional status, hyperactivation of AMPK was able to induce endothelial senescence. SIRT1 antagonized LKB1-dependent AMPK activation through promoting the deacetylation, ubiquitination and proteasome-mediated degradation of LKB1. The survival signaling of Akt was also found to be modulated by SIRT1 and LKB1, and could cross-regulate AMPK activity. CONCLUSIONS: SIRT1 and LKB1/AMPK are the 2 key sensor systems for regulating endothelial cell survival, proliferation and senescence. The protective activities of SIRT1 may be achieved at least in part by fine tuning the acetylation/deacetylation status and stabilities of LKB1 protein.

Senescence of cultured porcine coronary arterial endothelial cells is associated with accelerated oxidative stress and activation of NFkB.

AIMS: Endothelial dysfunction occurs following multiple passaging in vitro,but the molecular mechanisms involved remain unidentified. The present study defined the genomic changes related to dysfunction in cultured senescent endothelial cells. METHODS AND RESULTS: Senescent cells were produced by multiple passaging of porcine coronary arterial endothelial cells for up to 4 weeks. Genomic and proteomic studies on cultured cells at the first passage (P1) and the fourth passage (P4) were performed. Senescence and decreased NO production were observed in cells and several signaling pathways - such as IFN/STAT, IGF, TGF-beta, cytoskeleton rearrangement and lipid metabolism - were altered at P4, as judged from the microarray analysis. The basal and stimulated (by TNF-alpha) levels of NFkappaB were augmented in senescent cells in electrophoretic mobility shift assays in association with increased oxidative stress, increased p53 protein stability, and activated apoptotic pathways. The increased oxidative stress was alleviated by treatment with the superoxide dismutase mimetic MnTMPyP. CONCLUSIONS: After multiple passaging in vitro, porcine coronary endothelial cells exhibited dysfunction and senescence associated with reduced proliferative capacity, increased oxidative stress, and activation of the NFkappaB and p53 signaling pathways.

The presence and activity of SP-D in porcine coronary endothelial cells depend on Akt/PI3K, Erk and nitric oxide and decrease after multiple passaging.

Surfactant protein D (SP-D) mediates clearance of microorganisms and modulates inflammation in response to cytotoxic stimulation. It is present in various epithelia, but also in vascular smooth muscle and endothelial cells. Experiments were designed to determine whether or not SP-D is present in porcine coronary arterial endothelial cells and if so, to investigate the molecular mechanisms underlying this presence. The expression of SP-D, NO synthase, Akt 1/2 and Erk 1/2 proteins was determined in cultures at passages 1 (#1) and 4 (#4). SP-D in primary cells existed in three isoforms (37-38 kDa and 50 kDa). The 37-38 kDa SP-D forms were the dominant isoforms in the porcine endothelium and were prominent at #1 but partially lost at #4. Tumor necrosis factor-alpha (TNF-alpha) significantly augmented the level of SP-D expression at #1 but not at #4. The basal level of 37-38 kDa SP-D isoforms at #1 was reduced by L-NAME, wortmannin and PD 98059. The low basal expression at #4 could be increased by DETA NONOate (donor of NO) or insulin (activator of PI(3)K/Akt). The presence of nitric oxide synthase was reduced while that of Akt 1/2 and Erk 1/2 was increased at #4. In cells both at passages 1 and 4, TNF-alpha downregulated NO synthase and up-regulated p-Erk 1/2 protein. The present findings demonstrate the presence of SP-D in endothelial cells which is NO-, PI(3)K/Akt- and Erk-dependent. They suggest a protective role of SP-D in these cells.

Genomic changes in regenerated porcine coronary arterial endothelial cells.

OBJECTIVE: Genomic changes were defined in cultures of regenerated porcine coronary endothelial cells to explain the alterations that underlie their dysfunction. METHODS AND RESULTS: Regeneration of the endothelium was triggered in vivo by endothelial balloon denudation. After 28 days, both left circumflex (native cells) and left anterior descending (regenerated cells) coronary arteries were dissected, their endothelial cells harvested, and primary cultures established. The basal cyclic GMP production was reduced in regenerated cells without significant reduction in the response to bradykinin and A23187. The mRNA expression levels in both native and regenerated cells were measured by microarray and RT-PCR. The comparison revealed genomic changes related to vasomotor control (cyclooxygenase-1, angiotensin II receptor), coagulation (F2 and TFPI), oxidative stress (Mn SOD, GPX3, and GSR), lipid metabolism (PLA2 and HPGD), and extracellular matrix (MMPs). A-FABP and MMP7 were induced by regeneration. RT-PCR revealed upregulation of A-FABP and downregulation of eNOS and TR. The differential gene expression profiles were confirmed at the protein level by Western blotting for eNOS, F2, Mn SOD, MMP7, and TR. CONCLUSIONS: Cultures from regenerated coronary endothelial cells exhibit genomic changes explaining endothelial dysfunction and suggesting facilitation of coagulation, lipid peroxidation, and extracellular matrix remodeling.

Genistein reduces agonist-induced contractions of porcine coronary arterial smooth muscle in a cyclic AMP-dependent manner.

Low concentrations of genistein enhance the vasodilatation induced by endothelium-independent vasodilators. The present study examined whether or not low concentrations of genistein modulate contractions in isolated porcine coronary arteries. The role of second messengers in the response to genistein was also assessed. Arterial rings were studied in organ baths and contracted with KCl, U-46619 (9,11-dideoxy-9alpha, 11alpha-methanoepoxy prostaglandin F2alpha), 5-hydroxytryptamine (5-HT) or endothelin-1 in the absence or presence of genistein (< or =3 microM). Genistein significantly reduced agonist-induced but not KCl-induced contraction. Inhibition of endothelial nitric oxide synthase and disruption of endothelial function by Triton-X100 did not affect the modulation of contraction by genistein. The genistein-induced attenuation of contraction could be mimicked by both cAMP and cGMP analogs. However, only the cAMP-dependent protein kinase inhibitor, Rp-8-Br-cAMPS, abolished the effect of genistein. These results suggest that genistein reduces agonist-induced contraction by an endothelium-independent manner. This action is mediated via the cAMP-dependent signal transduction pathway.

The phytoestrogen genistein enhances endothelium-independent relaxation in the porcine coronary artery.

Genistein, a phytoestrogen, possesses cardioprotective effects. Responses to genistein (0.1-100 microM) were assessed in 9,11-dideoxy-9 alpha, 11 alpha-methanoepoxy prostaglandin F(2 alpha) (U46619)-contracted porcine coronary arterial rings, with significant relaxations at high concentrations. At concentrations with little relaxation, genistein (0.3-3 microM) did not affect relaxation produced by bradykinin and the calcium ionophore, A23187. In contrast, sodium nitroprusside- and cromakalim-induced relaxations were enhanced by genistein (3 microM). N(omega)-nitro-L-arginine methyl ester (L-NAME) (300 microM) or Triton X-100 (0.5%) did not affect the enhancement of relaxation by genistein. The tyrosine kinase inhibitor, tyrphostin 23 (30 microM), had no effect on sodium nitroprusside-elicited relaxation. In summary, genistein relaxed porcine coronary artery at relatively high concentrations. At a physiologically relevant concentration (3 microM), it is devoid of significant vascular effect, but enhanced endothelium-independent relaxations. This effect of genistein does not involve the nitric oxide synthase (NOS) pathway and the endothelium, and is mediated through a mechanism different from tyrosine kinase inhibition.