Identification of azabenzimidazoles as potent JAK1 selective inhibitors

We have identified a class of azabenzimidazoles as potent and selective JAK1 inhibitors. Investigations into the SAR are presented along with the structural features required to achieve selectivity for JAK1 versus other JAK family members. An example from the series demonstrated highly selective inhibition of JAK1 versus JAK2 and JAK3, along with inhibition of pSTAT3 in vivo, enabling it to serve as a JAK1 selective tool compound to further probe the biology of JAK1 selective inhibitors.

Discovery of potent KIFC1 inhibitors using a method of integrated high-throughput synthesis and screening

KIFC1 (HSET), a member of the kinesin-14 family of motor proteins, plays an essential role in centrosomal bundling in cancer cells, but its function is not required for normal diploid cell division. To explore the potential of KIFC1 as a therapeutic target for human cancers, a series of potent KIFC1 inhibitors featuring a phenylalanine scaffold was developed from hits identified through high-throughput screening (HTS). Optimization of the initial hits combined both design-synthesis-test cycles and an integrated high-throughput synthesis and biochemical screening method. An important aspect of this integrated method was the utilization of DMSO stock solutions of compounds registered in the corporate compound collection as synthetic reactants. Using this method, over 1500 compounds selected for structural diversity were quickly assembled in assay-ready 384-well plates and were directly tested after the necessary dilutions. Our efforts led to the discovery of a potent KIFC1 inhibitor, AZ82, which demonstrated the desired centrosome declustering mode of action in cell studies.

Discovery of (+)-N-(3-aminopropyl)-N-[1-(5-benzyl-3-methyl-4-oxo-[1,2]thiazolo[5,4-d]pyrimidin-6-yl)-2-methylpropyl]-4-methylbenzamide (AZD4877), a kinesin spindle protein inhibitor and potential anticancer agent

Structure-activity relationship analysis identified (+)-N-(3-aminopropyl)-N-[1-(5-benzyl-3-methyl-4-oxo-[1,2]thiazolo[5,4-d]pyrimidin-6-yl)-2-methylpropyl]-4-methylbenzamide (AZD4877), from a series of novel kinesin spindle protein (KSP) inhibitors, as exhibiting both excellent biochemical potency and pharmaceutical properties suitable for clinical development. The selected compound arrested cells in mitosis leading to the formation of the monopolar spindle phenotype characteristic of KSP inhibition and induction of cellular death. A favorable pharmacokinetic profile and notable in vivo efficacy supported the selection of this compound as a clinical candidate for the treatment of cancer.

Automated chemical synthesis: from resins to instruments

Solid-phase organic synthesis is now a prevalent activity in drug discovery. In keeping with this keen interest is the need to develop reliable automated synthesis instrumentation as well as polymeric supports and linkers suitable for the full range of organic synthesis applications. In this paper, we review our activities in the development of new and enabling tools for automated chemical synthesis, including the following: (i) new solid supports such as ArgoGel (PS-PEG-based) and Argo-X203 (PS-based); and (ii) the Nautilus 2400 system, a fully closed and inert automated chemistry development workstation. Selected chemistry optimization and synthesis examples performed on the Nautilus and new solid supports will be described.

Interference by pro-apolipoprotein A-I in apolipoprotein E phenotyping using chemical precipitation procedures

Lipoproteins of density, d less than 1.063, isolated by polyanion-cation precipitation methods, gave isoelectric focussing patterns of apolipoprotein E isoforms by rod-gel electrophoresis which differed from the corresponding patterns obtained from ultracentrifugally-derived very low density lipoproteins. The differences were sporadic and variable but the most common effect was an increased frequency of the E3 isoform. Two-dimensional analyses involving sodium dodecyl sulphate-polyacrylamide gel electrophoresis and immunoelectrophoresis against anti-apolipoprotein A-I indicated that contamination of precipitated lipoproteins with pro-apolipoprotein A-I was responsible for this phenomenon. It is suggested that two-dimensional techniques should be applied for definitive phenotyping if precipitated lipoproteins are used as source material.

Loss of A-apoprotein immunoreactivity during high-density lipoprotein separation

By use of an electroimmunoassay, concentrations of A-apoproteins were estimated in serum and in corresponding apoprotein fractions isolated by ultracentrifugation. These values were compared with high-density lipoprotein concentrations determined by analytical ultracentrifugation. Concentrations of A-apoproteins estimated in serum were considerably higher than in isolated high-density lipoprotein fractions. These discrepancies could not be accounted for entirely by material losses into other fractions during ultracentrifugal fractionation. No comparable differences in apoprotein-B concentrations were observed during the ultracentrifugal separation of low-density lipoprotein. Concentrations of A-apoproteins estimated in the residual serum after precipitation of low-density lipoproteins by heparin and manganous ions were also lower than in the corresponding whole sera. The discrepancies persisted after treatment of serum and isolated fractions with tetramethylurea, urea (9 mol/l), and by heating at 52 degrees C for 3 hours. It is considered that separation by ultracentrifugation induces subtle alterations in the surface structure of the lipoprotein species which give rise to changes in immunoreactivity.

Evaluation of the polyethylene glycol precipitation method for the estimation of high-density lipoprotein cholesterol

Treatment of fresh sera with polyethylene glycol 6000 at a final concentration of 100 g/l produced selective precipitation of low-density lipoproteins with only traces of contamination with high-density lipoproteins, as determined by electroimmunoassay using antisera to human alpha1-lipoprotein and human beta-lipoprotein. Supernatants collected for high-density lipoprotein-cholesterol estimation were free from low-density lipoproteins. Precipitates sedimented readily from specimens with high triglyceride contents, and secondary precipitation during enzymatic cholesterol determinations was absent. Values obtained by this method correlated well with those obtained by precipitation of low-density lipoproteins with heparin and manganous ions at concentrations optimal for discrete of lipoprotein classes (r = 0.975; p less than 0.001).

Changes in serum creatine kinase isoenzyme activities after surgical procedures and cardioversion

Serum activities of creatine kinase (CK) and its isoenzymes were monitored before and 16 to 20 hours after a variety of surgical procedures and cardioversion. Changes in total CK and CK MM activities in the surgical patients were consistent with the extent of trauma; changes in these activities in the cardioversion patients were more variable, ranging from -2 to 1829 U/l, and were unrelated to the applied electrical force. CK MB activity was unchanged after cystoscopy but rose moderately in 60% of patients after cholecystectomy, in 43% of patients requiring only implantation of a new pacemaker box, and in 87% of patients after implantation of an entire pacemaker system. No increase exceeded 6U/l. Fifty per cent of patients requiring cardioversion showed rises; the maximum value was 40.9 U/l.

Selective precipitation of very low density lipoproteins from fasting sera by heparin and manganese ions

Complete and discrete precipitation of very low density lipoproteins (VLDL) from fasting sera required heating at 40 degrees C for 60 min in the presence of 0.05 M manganous ions and heparin in a concentration dependent upon the VLDL content. The minimum polyanion concentration, employed with VLDL contents less than 1.0 g/l, was 85 mg/l; an increment of 5 mg/l was required for each 1.0 g/l increase in VLDL content. The products isolated by this procedure had electrophoretic, immunochemical and ultracentrifugal characteristics skin to those of native VLDL and were slightly contaminated with albumin. The reaction conditions did not affect adversely the subsequent precipitation of low density lipoproteins.

Plasma catecholamine levels and cardiac rhythm before and after cardiac catheterisation

Plasma catecholamine concentrations were estimated in a group of 17 fasting patients immediately before and 3 days after cardiac catheterisation. At both times electrocardiograms were recorded and blood pressures, heart rates, and respiration rates measured. Control catecholamine values were established in a group of 10 male and 10 female volunteers, bled at the same time of day under the same conditions of nutrition and posture. Levels of adrenaline and noradrenaline were increased substantially before catheterisation; 3 days later, the values were comparable to those of the control group, though still marginally higher. The increments in catecholamine levels were independent of sex and of the presence or otherwise of persistent supraventricular arrhythmias. In spite of the considerably raised catecholamine levels, electrocardiographic patterns remained unchanged, as did the other physiological values. The absence of any relation between enhanced catecholamine secretion and physiological effects is considered to be the result either of enhanced parasympathetic activity or of adaptation to a prolonged period of stress.

Changes in glomerular filtration rate following myocardial infarction

Cr EDTA clearance was measured in 10 patients immediately after uncomplicated myocardial infarction and 3 weeks later. The initial values (120 +/- 36 ml/min) were significantly higher than the later values (79 +/- 23 ml/min). Possible reasons for this are reviewed.

Serum lactate dehydrogenase isoenzyme activities in patients with asthma

Usher, D. J., Shepherd, R. J., and Deegan, T. (1974).Thorax, 29, 685-689. Serum lactate dehydrogenase isoenzyme activities in patients with asthma. Increases in the serum activities of several enzymes have been reported in patients with asthma. Liver damage, resulting from altered tensions of oxygen and carbon dioxide in the circulation, has been held to be responsible for the majority of this increase, although it has also been suggested that allergic reactions in the lungs might make some contribution.

This communication describes the application of a more specific enzyme assay, the serum lactic dehydrogenase (LDH) isoenzyme pattern, to asthma patients in an attempt to elucidate the source of the increase in enzyme activity. Raised activities of two isoenzymes, LDH-3 and LDH-5, comprised the bulk of the increase in total LDH activity; in contrast, the activities of LDH-1 and LDH-2 were virtually unaltered. Analysis of the distribution of isoenzyme activity in lung tissue homogenate, coupled with knowledge of that in liver, suggested that both tissues contributed towards the effects observed. It appeared probable that the increment in LDH-3 activity arose from lung involvement, whereas the major portion of the increment in LDH-5 activity was derived from the liver.

99m Tc-labelled serum albumin in cardiac output and blood volume studies

The use of human serum albumin labelled with iodine-131 (RIHSA) as the radioactive indicator in the measurement of cardiac output by the external counting technique is not ideal since the emission characteristics, physical half-life, and physiological fate restrict the amount that can be administered. A more suitable material, especially because of the short physical half-life of the isotope involved, is albumin labelled with technetium-99m.

This communication describes a simple three-stage process for the preparation of such a complex which was then tested in subjects with no impairment of cardiac performance for its suitability in assays of cardiac output by the external counting method. Values were within the same range as those obtained with RIHSA in comparable subjects. Blood volumes estimated with ^99mTc-albumin were within the limits of physiological variation of values derived with RIHSA in the same subjects.

Serial blood samplings and urine collection during a period of 24 hours after administration showed that the preparation was lost continuously from the circulation at a more rapid rate than RIHSA. The greatest loss was in the first few hours when most of the urinary excretion of the isotope occurred. Comparison of the present data with published results using an alternative preparation suggests that our product may be more stable.