Identification and preclinical characterization of AZ-23, a novel, selective, and orally bioavailable inhibitor of the Trk kinase pathway

Tropomyosin-related kinases (TrkA, TrkB, and TrkC) are receptor tyrosine kinases that, along with their ligands, the neurotrophins, are involved in neuronal cell growth, development, and survival. The Trk-neurotrophin pathway may also play a role in tumorigenesis through oncogenic fusions, mutations, and autocrine signaling, prompting the development of novel Trk inhibitors as agents for cancer therapy. This report describes the identification of AZ-23, a novel, potent, and selective Trk kinase inhibitor. In vitro studies with AZ-23 showed improved selectivity over previous compounds and inhibition of Trk kinase activity in cells at low nanomolar concentrations. AZ-23 showed in vivo TrkA kinase inhibition and efficacy in mice following oral administration in a TrkA-driven allograft model and significant tumor growth inhibition in a Trk-expressing xenograft model of neuroblastoma. AZ-23 represents a potent and selective Trk kinase inhibitor from a novel series with the potential for use as a treatment for cancer.

Carotid intimal-media thickness and endothelial function in young patients with history of myocardial infarction

AIM

The aim of the study was to evaluate the prevalence of carotid atherosclerosis and endothelial dysfunction in 45 young patients (38 mens and 7 females) with myocardial infarction (MI), age 29-45, mean age 42+/-3 years, to verify its possible role as a marker of coronary atherosclerosis.

METHODS

Vascular echography was performed to verify the presence of carotid atherosclerosis and/or endothelial dysfunction in 45 young patients with MI and in 45 healthy control subjects well matched for age and sex.

RESULTS

We observed a normal intima media thickness (IMT) only in 30% of patients with juvenile myocardial infarction (JMI) compared with 66% in the control group (P<0.0001) and 34% of patients showed an increased IMT compared with 24% of healthy subjects (P<0.0001). Compared with control subjects, patients with JMI had lower flow-mediated reactivity of the brachial arteries (P<0.05). There was a negative linear relationship between flow-mediated dilation and IMT (P<0.001). The severity of coronary artery disease (CAD) was correlated with increased IMT and with a lower flow-mediated dilation. Finally, multiple regression analysis, demonstrated that both brachial-artery reactivity and carotid IMT were significantly and independently correlated with severity of CAD.

CONCLUSIONS

Structural (carotid atherosclerosis) and functional changes (endothelial dysfunction) were present at an early age in the arteries of persons with history of JMI.

Short term prognostic role of NT-proBNP in patients after myocardial infarction

AIM

The clinical and prognostic role of cardiac natriuretic peptides (CNP) in patients with heart failure is well known; recently, several studies have evaluated the possibility of using CNP to evaluate their potential prognostic role in patients with acute coronary syndromes (ACS). The aim of this study was to evaluate the short term prognostic value of NT-proBNP in 70 patients admitted for ACS.

METHODS

The authors studied 70 patients with ACS, evaluating, at admission, clinical-anamnestic, instrumental and laboratory characteristics including NT-proBNP plasma levels. Patients were monitored in a 6-month-follow-up to record adverse fatal events and their possible correlation with baseline characteristics.

RESULTS

The incidence of adverse events during the follow-up period was 28% (10 patients). In patients with adverse events, the authors observed lower left ventricle ejection fraction (P=0.01), higher prevalence of ST elevation myocardial infarction (P=0.03) and higher NT-proBNP levels (P=0.03), compared to those without adverse events. Moreover, the logistic regression analysis underlined how ST elevation myocardial infarction (P=0.05) and higher NT-proBNP levels (P=0.05) were the only predictive variables for adverse events during the follow up period.

CONCLUSIONS

This study demonstrates the short term prognostic role of NT-pro BNP in patients admitted for ACS.

Prognostic role of endothelial dysfunction and carotid intima-media thickness in patients undergoing coronary stent implantation

AIM

Impaired endothelial function and increased carotid intima-media thickness are key events in the atherosclerotic process and predict future cardiovascular events in subjects with and without coronary artery disease. The purpose of this study was to investigate whether the vasodilator response to increased flow in the brachial artery and the presence of carotid lesions may have a prognostic significance for in-stent restenosis in patients undergoing coronary angioplasty.

METHODS

The study population included 58 patients undergoing percutaneous coronary intervention (PCI) with stenting and at least 10 months of follow-up. All patients underwent ultrasound detection of brachial artery reactivity 30 days after PCI. Flow mediated dilatation (FMD) was investigated after 5 minutes of occlusion of the artery and nitroglycerin mediated dilation (NMD) was investigated after administration of sublingual nitrates. Vascular echography was performed to measure intima media thickness (IMT) of carotid arteries. At baseline we evaluated all the established traditional cardiovascular risk factors. We also subdivided our study cohort according to values of FMD in patients with FMD above and patients below the median value.

RESULTS

Patients with FMD above the median value showed higher prevalence of hypertension (P=0.002), diabetes (P=0.02) and carotid IMT (P=0.006) than those below the median. Brachial FMD was inversely correlated (P=0.001) to carotid IMT. At the end of follow-up clinical events occurred in nine patients. In a multivariate analysis, including all the variables evaluated at baseline, carotid IMT (P=0.02), level of glycemia (P=0.001), a lower FMD (P=0.005) and presence of carotid plaque remained the only variables predictive of restenosis.

CONCLUSIONS

Evaluation of FMD and carotid IMT may provide important prognostic information in patients undergoing PCI.

Clinical significance of macrophage colony stimulating factor levels in acute coronary syndrome

AIM

The aim of this paper was to ascertain whether macrophage colony stimulating factor (MCSF) serum levels, measured during the acute phase of coronary syndromes (ACS), are useful to predict short term outcomes.

METHODS

Seventy-four consecutive patients (mean age: 66+/-12), admitted to the Intensive Coronary Care Unit of Palermo University Hospital (Italy) affected by ACS were observed; 39 patients showed a non ST elevation (NSTEMI) and 35 showed a ST elevation myocardial infarction (STEMI). During the hospital stay, all patients underwent echocardiography and 84% of patients received coronary angiography. Peripheral venous blood samples were collected for the determination of serum levels of MCSF, C-reactive protein (CRP), fibrinogen, I troponin and complete lipid pattern.

RESULTS

There was no significant difference in MCSF concentrations for STEMI versus NSTEMI patients (326.65+/-143.87 vs 297.15+/-110.43 pg/mL, P=NS). Higher levels of MCSF (363.00+/-147.61 vs 251.00+/-186.69, P=0.03) and CRP (1.04+/-0.40 vs 0.97+/-0.50 mg/L, P=0.03) were found in patients with a worst in hospital stay (recurrence of angina, re-infarction, death) and with a more severe coronary artery disease (330.03+/-241.51 vs 223.61+/-128.29 pg/mL, P=0.04 and 1.14+/-0.50 vs 0.60+/-0.22 mg/L, P=0.05).

CONCLUSIONS

MCSF levels are useful in the prediction of short term prognosis in ACS patients.

The G67E mutation in hMLH1 is associated with an unusual presentation of Lynch syndrome

Germline mutations in the mismatch repair (MMR) genes are associated with Lynch syndrome, also known as hereditary non-polyposis colorectal cancer (HNPCC) syndrome. Here, we characterise a variant of hMLH1 that confers a loss-of-function MMR phenotype. The mutation changes the highly conserved Gly67 residue to a glutamate (G67E) and is reminiscent of the hMLH1-p.Gly67Arg mutation, which is present in several Lynch syndrome cohorts. hMLH1-Gly67Arg has previously been shown to confer loss-of-function (Shimodaira et al, 1998), and two functional assays suggest that the hMLH1-Gly67Glu protein fails to sustain normal MMR functions. In the first assay, hMLH1-Gly67Glu abolishes the protein's ability to interfere with MMR in yeast. In the second assay, mutation of the analogous residue in yMLH1 (yMLH1-Gly64Glu) causes a loss-of-function mutator phenotype similar to yMLH1-Gly64Arg. Despite these molecular similarities, an unusual spectrum of tumours is associated with hMLH1-Gly67Glu, which is not typical of those associated with Lynch syndrome and differs from those found in families carrying the hMLH1-Gly67Arg allele. This suggests that hMLH1 may have different functions in certain tissues and/or that additional factors may modify the influence of hMLH1 mutations in causing Lynch syndrome.

Identification of 4-aminopyrazolylpyrimidines as potent inhibitors of Trk kinases

The design, synthesis and biological evaluation of a series of 4-aminopyrazolylpyrimidines as potent Trk kinase inhibitors is reported. High-throughput screening identified a promising hit in the 4-aminopyrazolylpyrimidine chemotype. Initial optimization of the series led to more potent Trk inhibitors. Further optimization using two strategies resulted in significant improvement of physical properties and led to the discovery of 10z (AZ-23), a potent, orally bioavailable Trk A/B inhibitor. The compound offers the potential to test the hypothesis that modulation of Trk activity will be of benefit in the treatment of cancer and other indications in vivo.

The role of the N-terminal caspase cleavage site in the nucleoprotein of influenza A virus in vitro and in vivo

The N-terminal caspase cleavage in the nucleoprotein (NP) of influenza A virus is correlated with the host origin of the virus, thus could be a molecular determinant for host range. We studied how mutations targeting the NP cleavage motif of human and avian influenza viruses affect virus replication in vitro and in vivo. The "avian-like" D16-->G substitution in the NP, which makes this protein resistant to cleavage, did not significantly affect the human A/Puerto Rico/8/34 (H1N1) virus replication in vitro but decreased the lethality of this virus in mice by 68-fold. Gene incompatibility contributed to the attenuated phenotype of the reassortant A/Puerto Rico/8/34 virus with avian NP derived from A/Teal/Hong Kong/w312/97 (H6N1) virus in vitro and in vivo. Insertion of the "human-like" G16-->D mutation into avian NP, which resulted in susceptibility to caspase cleavage, did not rescue virulence, but made the reassortant virus even more attenuated. Introducing the human-like G16-->D substitution into the NP of highly pathogenic A/Vietnam/1203/04 (H5N1) virus decreased lethality in mice. We confirmed that position 16, which associated with the N-terminal caspase cleavage of the NP, is important for optimal virus fitness in vitro and in vivo. An avian-like mutation at position 16 in the NP of human virus as well as a human-like substitution at this residue in avian NP both resulted in virus attenuation.

Extracoronary atherosclerosis in patients with chronic ischemic heart disease: relationship with risk factors and the severity of coronary artery disease

AIM

The aim of the present study was to investigate the prevalence of carotid and/or peripheral atherosclerotic lesions in patients with chronic ischemic heart disease (previous acute myocardial infarction [AMI] or stable angina).

METHODS

We studied 248 patients (168 male and 80 female), mean age 63+/-10 years, which were investigated for traditional risk factors. Systolic blood pressure, body mass index, lipid profile, fasting glucose and plasma fibrinogen were also measured. We assessed the prevalence of atherosclerotic lesions in carotid and lower limb arteries, by ultrasound duplex scanning (UDS).

RESULTS

Angina was present in 33% of the patients, a previous AMI in 67%, a previous transient ischemic attack in 4% and a previous ischemic stroke in 6% of patients. A total of 195 patients underwent coronary angiography: 1 vessel was involved in 48% of patients, 2 vessels in 33%, and 3 vessels in 19%. Detecting peripheral atherosclerotic lesions by UDS, increased intima-media thickness (IMT) or plaques in carotid arteries were found in 232 patients (94%) and carotid stenosis >70% in 13 patients (5%). In lower limb arteries, IMT or plaques were present in 202 patients (82%) and a stenosis >70% in 18 patients (7%). Severity of coronary artery disease (CAD) was correlated to extracoronary atherosclerosis: carotid and lower limb arterial atherosclerosis was detected in 73% of patients with 1 vessel, in 83% of patients with 2 vessel, in 87% of those with 3 vessel CAD.

CONCLUSION

Our study suggests that in patients with CAD, it is useful to screen the peripheral circulation by non-invasive tests, such as UDS. Patients with the diagnosis of ischemic heart disease and combined extracoronary atherosclerosis need a careful follow-up and a more aggressive therapy for secondary prevention.

Lungenembolie

In the population the annual incidence of pulmonary embolism amounts to 1.3-2.8 per 1000 at the age of 65-89 years. Mortality reaches about 17% within the first 3 months. Acute pulmonary embolism is characterized by an increase in pulmonary arterial pressure and an impairment of the pulmonary gas exchange. Elevation of the right cardiac pressure up to right heart decompensation may follow. In addition, hypoxemia, hyperventilation, dead space ventilation, right to left shunting, bronchoconstriction, and vasoconstriction may occur. Clinical examination, ECG, laboratory findings such as elevated D-dimer, blood gas analysis, ultrasound examination of the veins of the lower extremities, and transthoracic echocardiography are acutely available diagnostic methods of an emergency department. In addition, extensive diagnostic procedures like pulmonary scintigraphy and pulmonary angiography may be required. The aim is to get a definite diagnosis as quickly as possible to direct therapy. In acute pulmonary embolism with cardiac shock, monitoring and stabilization of the circulatory function as well as an appropriate anticoagulant therapy are essential. In some cases surgery or a local fibrinolytic intervention is indicated.

Molecular changes in the polymerase genes (PA and PB1) associated with high pathogenicity of H5N1 influenza virus in mallard ducks

The highly pathogenic (HP) influenza viruses H5 and H7 are usually nonpathogenic in mallard ducks. However, the currently circulating HP H5N1 viruses acquired a different phenotype and are able to cause mortality in mallards. To establish the molecular basis of this phenotype, we cloned the human A/Vietnam/1203/04 (H5N1) influenza virus isolate that is highly pathogenic in ferrets, mice, and mallards and found it to be a heterogeneous mixture. Large-plaque isolates were highly pathogenic to ducks, mice, and ferrets, whereas small-plaque isolates were nonpathogenic in these species. Sequence analysis of the entire genome revealed that the small-plaque and the large-plaque isolates differed in the coding of five amino acids. There were two differences in the hemagglutinin (HA) gene (K52T and A544V), one in the PA gene (T515A), and two in the PB1 gene (K207R and Y436H). We inserted the amino acid changes into the wild-type reverse genetic virus construct to assess their effects on pathogenicity in vivo. The HA gene mutations and the PB1 gene K207R mutation did not alter the HP phenotype of the large-plaque virus, whereas constructs with the PA (T515A) and PB1 (Y436H) gene mutations were nonpathogenic in orally inoculated ducks. The PB1 (Y436H) construct was not efficiently transmitted in ducks, whereas the PA (T515A) construct replicated as well as the wild-type virus did and was transmitted efficiently. These results show that the PA and PB1 genes of HP H5N1 influenza viruses are associated with lethality in ducks. The mechanisms of lethality and the perpetuation of this lethal phenotype in ducks in nature remain to be determined.