Diversity of US participants in AstraZeneca-sponsored clinical trials

BACKGROUND

To develop medicines that are safe and efficacious to all patients, clinical trials must enroll appropriate target populations, but imbalances related to race, ethnicity and sex have been reported. A comprehensive analysis and improvement in understanding representativeness of patient enrollment in industry-sponsored trials are key public health needs.

METHODS

We assessed race/ethnicity and sex representation in AstraZeneca (AZ)-sponsored clinical trials in the United States (US) from 2010 to 2022, compared with the 2019 US Census.

RESULTS

In total, 246 trials representing 95,372 patients with complete race/ethnicity and sex records were analyzed. The proportions of different race/ethnicity subgroups in AZ-sponsored clinical trials and the US Census were similar (White: 69.5% vs 60.1%, Black or African American: 13.3% vs 12.5%, Asian: 1.8% vs 5.8%, Hispanic: 14.4% vs 18.5%). We also observed parity in the proportions of males and females between AZ clinical trials and US Census (males: 52.4% vs 49.2%, females: 47.6% vs 50.8%). Comparisons of four distinct therapy areas within AZ (Respiratory and Immunology [R&I]; Cardiovascular, Renal, and Metabolism [CVRM]; Solid Tumors; and Hematological Malignancies), including by trial phases, revealed greater variability, with proportions observed above and below US Census levels.

CONCLUSION

This analysis provides the first detailed insights into the representativeness of AZ trials. Overall, the proportions of different race/ethnicity and sex subgroups in AZ-sponsored clinical trials were broadly aligned with the US Census. We outline some of AZ's planned health equity initiatives that are intended to continue to improve equitable patient enrollment.

Myeloperoxidase Levels and Its Product 3-Chlorotyrosine Predict Chronic Kidney Disease Severity and Associated Coronary Artery Disease

BACKGROUND

The role of myeloperoxidase in chronic kidney disease (CKD) and its association with coronary artery disease (CAD) is controversial. In this study, we compared myeloperoxidase and protein-bound 3-chlorotyrosine (ClY) levels in subjects with varying degrees of CKD and tested their associations with CAD.

METHODS

From Clinical Phenotyping Resource and Biobank Core, 111 patients were selected from CKD stages 1 to 5. Plasma myeloperoxidase level was measured using enzyme-linked-immunosorbent assay. Plasma protein-bound 3-ClY, a specific product of hypochlorous acid generated by myeloperoxidase was measured by liquid chromatography mass spectrometry.

RESULTS

We selected 29, 20, 24, 22, and 16 patients from stages 1 to 5 CKD, respectively. In a sex-adjusted general linear model, mean ± SD of myeloperoxidase levels decreased from 18.1 ± 12.3 pmol in stage 1 to 10.9 ± 4.7 pmol in stage 5 (p = 0.011). In patients with and without CAD, the levels were 19.1 ± 10.1 and 14.8 ± 8.7 pmol (p = 0.036). There was an increase in 3-ClY mean from 0.81 ± 0.36 mmol/mol-tyrosine in stage 1 to 1.42 ± 0.41 mmol/mol-tyrosine in stage 5 (p < 0.001). The mean 3-ClY levels in patients with and without CAD were 1.25 ± 0.44 and 1.04 ± 0.42 mmol/mol-tyrosine (p = 0.023), respectively. C-statistic of ClY when added to myeloperoxidase level to predict CKD stage 5 was 0.86, compared to 0.79 for the myeloperoxidase level alone (p = 0.0097).

CONCLUSION

The myeloperoxidase levels decrease from stages 1 to 5, whereas activity increases. In contrast, both myeloperoxidase and ClY levels rise in the presence of CAD at various stages of CKD. Measuring both plasma myeloperoxidase and 3-CLY levels provide added value to determine the burden of myeloperoxidase-mediated oxidative stress.

Inhibition of T-cell activation by the CTLA4-Fc Abatacept is sufficient to ameliorate proteinuric kidney disease

Diabetic nephropathy (DN) remains an unmet medical challenge as its prevalence is projected to continue to increase and specific medicines for treatment remain undeveloped. Activation of the immune system, in particular T-cells, is emerging as a possible mechanism underlying DN disease progression in humans and animal models. We hypothesized that inhibition of T-cell activation will ameliorate DN. Interaction of B7-1 (CD80) on the surface of antigen presenting cells with its binding partners, CTLA4 (CD152) and CD28 on T-cells, is essential for T-cell activation. In this study we used the soluble CTLA4-Fc fusion protein Abatacept to block cell surface B7-1, preventing the cellular interaction and inhibiting T-cell activation. When Abatacept was dosed in an animal model of diabetes-induced albuminuria, it reduced albuminuria in both prevention and intervention modes. The number of T-cells infiltrating the kidneys of DN animals correlated with the degree of albuminuria, and treatment with Abatacept reduced the number of renal T-cells. As B7-1 induction has been recently proposed to underlie podocyte damage in DN, Abatacept could be efficacious in DN by protecting podocytes. However, this does not appear to be the case as B7-1 was not expressed in 1) kidneys of DN animals; 2) stimulated human podocytes in culture; or 3) glomeruli of DN patients. We conclude that Abatacept ameliorates DN by blocking systemic T-cell activation and not by interacting with podocytes.

Proteomic analysis of striatal proteins in the rat model of l-DOPA-induced dyskinesia

L-DOPA-induced dyskinesia (LID) is among the motor complications that arise in Parkinson's disease (PD) patients after a prolonged treatment with L-DOPA. To this day, transcriptome analysis has been performed in a rat model of LID [Neurobiol. Dis., 17 (2004), 219] but information regarding the proteome is still lacking. In the present study, we investigated the changes occurring at the protein level in striatal samples obtained from the unilaterally 6-hydroxydopamine-lesion rat model of PD treated with saline, L-DOPA or bromocriptine using two-dimensional difference gel electrophoresis and mass spectrometry (MS). Rats treated with L-DOPA were allocated to two groups based on the presence or absence of LID. Among the 2000 spots compared for statistical difference, 67 spots were significantly changed in abundance and identified using matrix-assisted laser desorption/ionization time-of-flight MS, atmospheric pressure matrix-assisted laser desorption/ionization and HPLC coupled tandem MS (LC/MS/MS). Out of these 67 proteins, LID significantly changed the expression level of five proteins: alphabeta-crystalin, gamma-enolase, guanidoacetate methyltransferase, vinculin, and proteasome alpha-2 subunit. Complementary techniques such as western immunoblotting and immunohistochemistry were performed to investigate the validity of the data obtained using the proteomic approach. In conclusion, this study provides new insights into the protein changes occurring in LID.

Expression pattern of JunD after acute or chronic l-DOPA treatment: Comparison with ΔFosB

In this study, we have used 6-hydroxydopamine-lesioned rats to examine changes in striatal junD and fosB/deltafosB expression induced by acute and chronic treatment with L-DOPA (5 and 15 days). Changes at the protein levels were studied using Western immunoblotting while mRNA changes were compared using in situ hybridization histochemistry. We observed a significant increase in the level of deltaFosB proteins after chronic treatment with L-DOPA, an effect that was not observed for JunD proteins. In addition, the upregulation of deltaFosB was already present after an acute treatment but increased upon chronic treatment. By contrast, junD and deltafosB mRNA were both upregulated significantly above control levels after an acute injection of L-DOPA. In conclusion, this study suggests a differential expression pattern of junD and deltafosB in a rat model of L-DOPA-induced dyskinesia. The upregulation of deltaFosB protein, but not JunD, is likely to reflect an increased stability of the deltaFosB proteins without ongoing enhanced transcription of the encoding genes.

AMPA receptor phosphorylation is selectively regulated by constitutive phospholipase A(2) and 5-lipoxygenase activities

The present investigation provides the first indication that constitutive, calcium-independent phospholipase A2 activity (iPLA2) modulates phosphorylation of the alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) subtype of glutamate receptors. Preincubation of frozen-thawed brain sections with two iPLA2 inhibitors, bromoenol lactone (BEL) or palmitoyl trifluoromethyl ketone (PACO), produced a dose-dependent enhancement in phosphorylation at both Ser831 and Ser845 sites on the GluR1 subunit of AMPA receptors. This effect was not associated with changes in phosphorylation at the Ser sites of either the GluR2/3 subunits of AMPA receptors or the NR1 subunits of N-methyl-D-aspartate (NMDA) receptors, nor was it reproduced by inhibition of the calcium-dependent form of PLA2 activity. These results suggest that the effects of these inhibitors are selective to GluR1 subunits and that they are dependent on iPLA2 activity. The ability of iPLA2 inhibitors to increase GluR1 phosphorylation was mimicked by the 5-lipoxygenase (5-LO) inhibitor MK-886, but not by blockers of 12-lipoxygenase (12-LO) or cyclooxygenase. Additional experiments indicated that calcium-mediated truncation of GluR1 subunits was reduced by iPLA2 inhibitors, an effect that was not correlated with overall changes in the distribution of AMPA receptors between intracellular and membrane compartments prepared from whole brain sections. However, quantitative autoradiographic analysis indicated enhanced 3H-AMPA binding to the CA1 stratum radiatum of the hippocampus in BEL-treated sections. Saturation kinetics experiments demonstrated that this binding augmentation was due to an increase in the maximal number of AMPA binding sites. Altogether, our results point to the conclusion that basal iPLA2 activity, through the generation of 5-LO metabolites, regulates AMPA receptor phosphorylation of GluR1 subunits, an effect that might selectively influence the number of membrane receptors in area CA1 of the hippocampus.

Strain-related variations of AMPA receptor modulation by calcium-dependent mechanisms in the hippocampus: contribution of lipoxygenase metabolites of arachidonic acid

Several studies have demonstrated that C57 and DBA mice exhibit behavioural differences in diverse learning tasks as well as variations in the expression of long-term potentiation (LTP) in the hippocampus. In the present investigation, we tested the possibility that these differences between the two strains might be attributable to differential regulation of hippocampal alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) receptors by calcium-dependent mechanisms. Using in vitro receptor autoradiography, we found that calcium treatment of C57 mice sections resulted in a marked increase of 3H-AMPA binding in areas CA3 and CA1 of the hippocampus and in the dentate gyrus. However, we discovered that the ability of calcium to upregulate 3H-AMPA binding in the DBA strain was much lower than in corresponding regions from the C57 strain. Western blot and immunohistochemical experiments indicated that truncation of AMPA receptor subunits by calcium-dependent mechanisms was possibly not responsible for the binding differences, as no significant variations in glutamate receptor subunit 1 (GluR1) and GluR2/3 immunoreactivity were observed between the two strains after calcium treatment. Interestingly, we found that strain-related variations in the regulation of 3H-AMPA binding by calcium were totally eliminated when brain sections were preincubated with preferential inhibitors of lipoxygenase (LO) pathways of arachidonic acid (AA) metabolism. Taken together, these results suggest that calcium-induced regulation of AMPA receptors varies between the two strains and that this variation might be linked to the production of specific AA metabolites.

Alpha and beta estradiol protect neuronal but not native PC12 cells from paraquat-induced oxidative stress

Oxidative stress is currently considered a mediator of cell death in several neurodegenerative diseases. Notably, it may play an important role in the degeneration of dopamine neurons of the substantia nigra in Parkinson's disease. We examined the effect of a strong oxidant, the herbicide paraquat, on cell distress using native and neuronal pheochromocytoma PC12 cells. Paraquat administration for 8 hours induced a significant cellular death in both native and in neuronal PC12 cells. Since the anti-oxidant properties of estrogens may promote neuroprotection in vitro and in vivo, we then investigated the ability of estradiol stereoisomers, 17alpha-estradiol and 17- beta-estradiol, to rescue PC12 cells submitted to paraquat-induced oxidative stress. Our results show a protective effect of both estradiol stereoisomers in neuronal PC12 cells treated with paraquat, whereas this effect could not be observed in native PC12 cells. We also demonstrate that estrogen receptor beta protein expression is modulated by paraquat administration in native PC12 cells, while paraquat does not change estrogen receptor beta ?expression in neuronal PC12 cells. Paraquat also decreases estrogen receptor alpha in neuronal PC12 cells, thus suggesting new routes for paraquat to collapse cellular metabolism. Besides, the oxidation of dihydrodhodamine-123 into fluorescent rhodamine in the presence of paraquat but not in presence of paraquat and 17 alpha-estradiol or 17 beta-estradiol, sustain a possible direct scavenging role of both estradiol stereoisomers.

Effects of estradiol, phytoestrogens, and Ginkgo biloba extracts against 1-methyl-4-phenyl-pyridine-induced oxidative stress

Oxidative stress has been recently considered as a mediator of nerve cell death in several neurodegenerative diseases. We studied the effect of the parkinsonism-inducing toxine 1-methyl-4-phenyl-pyridine (MPP+) on several parameters of cell distress using native and neuronal PC12 cells. Then, since estrogens have been reported to prevent neuronal degeneration caused by oxidative damage, we investigated the ability of 17beta- estradiol (E2); two Ginkgo biloba extracts, EGb 761 and Cp 202; as well as two flavonoids, quercetin and kaempferol, to rescue PC12 cells submitted to MPP+- induced oxidative stress. Our results consistently show that both Ginkgo biloba extracts could prevent cell death in native and neuronal PC12 cells, while in neuronal PC12 cells also quercetin and E2 could reverse MPP+ neurotoxic effet. Western blot analysis demonstrated that MPP+ injuries might modulate dopamine transporter (DAT) protein expression but not estrogen receptor beta (ERbeta) protein expression. EGb 761 and Cp 202 also modulate DAT and ERbeta protein expression in neuronal cells. From these studies, we outline the importance of testing estrogen-like plant-derived molecules as potent antioxidants and examine their effect on protein expression.

Inositol hexakisphosphate-mediated regulation of glutamate receptors in rat brain sections

D-myo-inositol 1,2,3,4,5,6-hexakisphosphate (InsP6), one of the most abundant inositol phosphates within cells, has been proposed to play a key role in vesicle trafficking and receptor compartmentalization. In the present study, we used in vitro receptor autoradiography, subcellular fractionation, and immunoblotting to investigate its effects on alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) and N-methyl-D-aspartate (NMDA) receptors. Qualitative and quantitative analysis of 3H-AMPA binding indicated that incubation of frozen-thawed brain sections with InsP6 at 35 degrees C enhanced AMPA receptor binding in several brain regions, with maximal increases in the hippocampus and cerebellum. Moreover, saturation kinetics demonstrated that InsP6-induced augmentation of AMPA binding was due to an increment in the maximal number of AMPA binding sites. At the immunological level, Western blots performed on crude mitochondrial/synaptic (P2) fractions revealed that InsP6 (but not InsP5 and InsP3) treatment increased glutamate receptor (GluR)1 and GluR2 subunits of AMPA receptors, an effect that was associated with concomitant reductions in microsomal (P3) fractions. Interestingly, the InsP6-induced modulation of AMPA receptor binding was blocked at room temperature, and pretreatment with heparin also dampered its action on both AMPA receptor binding and GluR subunits. These effects of InsP6 appear to be specific to AMPA receptors, as neither 3H-glutamate binding to NMDA receptors nor levels of NR1 and NR2A subunits in P2 and P3 fractions were affected. Taken together, our data strongly suggest that InsP6 specifically regulates AMPA receptor distribution, possibly through a clathrin-dependent process.

Up-regulation of glutamate receptors is associated with LTP defects in the early stages of diabetes mellitus

AIMS/HYPOTHESIS

Recent studies involving electrophysiology and immunolabelling indicate that short-term insulin treatment of hippocampal neurons in culture induces changes in glutamate receptor function, suggesting that this receptor system can be altered on a relatively rapid time scale during diabetic conditions. To investigate this hypothesis, we examined whether brain glutamate receptors and long-term potentiation are altered in the early stages of diabetes mellitus in non-obese diabetic mice, a genetic model of Type I (insulin-dependent) diabetes mellitus.

METHODS

In vitro receptor autoradiography and immunoblotting were used to study the impact of diabetes on brain glutamate receptors. From an electrophysiological point of view, field potential recordings were also examined in area CA1 of hippocampal slices to determine the influence of diabetes on long-term potentiation.

RESULTS

Quantitative autoradiographic analysis revealed enhanced 3H-glutamate binding to several brain regions of diabetes mice, with maximal increases in the cerebral cortex and hippocampus. Saturation kinetics within the cerebral cortex disclosed that this change of 3H-glutamate was possibly due to an increase in the maximal number of N-methyl- D-aspartate binding sites, an interpretation that was corroborated by Western blot analysis of N-methyl- D-aspartate 2A subunits. Impairment in the expression of hippocampal long-term potentiation was also observed in diabetic mice, while the failure to elicit synaptic potentiation was prevented by insulin treatment.

CONCLUSION/INTERPRETATION

Because glutamate receptors are thought to be involved in several degenerative processes, our results suggest that up-regulation of these receptors in the early stages of diabetes could represent an important mechanism underlying neurological complications within the brain of diabetic patients.

AMPA receptor modulation in previously frozen mouse brain sections: opposite effects of calcium in the cortex and hippocampus

Various forms of synaptic plasticity in the brain have been proposed to result from modifications in the properties of glutamate receptors by calcium-dependent mechanisms. In the present study, changes in glutamate receptors elicited by calcium treatment of previously frozen mouse brain sections were evaluated by qualitative as well as quantitative analysis of tritiated ligand binding to both alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) and N-methyl-D-aspartate (NMDA) glutamate receptor subtypes. Quantitative analysis revealed that 3H-AMPA binding was reduced in a dose-dependent manner by calcium in the cerebral cortex and striatum formations. However, an opposite change in AMPA receptor properties was observed in the hippocampus, as calcium generated an increase of AMPA binding in all hippocampal fields. Analysis of the saturation kinetics of 3H-AMPA binding showed that the calcium-induced augmentation of AMPA binding in the stratum radiatum of the CA1 region was due to an alteration in the maximal number of sites, while the reduction of binding elicited by calcium in the cortex appeared to be due to modified AMPA receptor affinity. Calcium-induced downregulation of AMPA receptor affinity in the cortex and striatum was affected by baicalein, a selective inhibitor of the lipoxygenase pathways of arachidonic acid metabolism, whereas the same inhibitor did not modify calcium-mediated upregulation of receptor number in the CA1 region of the hippocampus. On the other hand, the effect of calcium appeared to be specific for the AMPA receptor, as the same treatment did not affect glutamate binding to the NMDA glutamate receptor subtype. Our results suggest the possibility that, depending on the brain regions, calcium ions may generate opposite modulation of AMPA receptor properties. Because the regulation of AMPA receptors by calcium-dependent enzymes has been implicated in synaptic plasticity, our results suggest that regional variations in the effect of calcium on AMPA binding account for differential plasticity at glutamatergic synapses.

AMPA receptor regulation and LTP in the hippocampus of young and aged apolipoprotein E-deficient mice

In the present study, modulation of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptors by phosphatidylserine (PS) and synaptic plasticity were investigated in the hippocampus of young (4-month-old) and aged (18-month-old) apolipoprotein E (apoE)-deficient mice. Qualitative as well as quantitative analysis of brain sections in both young and aged apoE-deficient mice did not reveal any substantial changes of AMPA receptor binding in the various hippocampal regions, compared to age-matched controls. Nevertheless, enhancement of AMPA receptor binding elicited by PS treatment was found to be abolished in most hippocampal regions of young apoE-deficient mice, while modulation of AMPA receptors by this phospholipid was not significantly altered in the hippocampal formation of aged apoE-deficient animals. At the electrophysiological level, long-term potentiation (LTP) induced by theta burst stimulation was lower in area CA1 of the hippocampus of young, but not aged, apoE-deficient mice compared to age-matched controls. These results confirm that apoE is important for AMPA receptor regulation and LTP expression in the hippocampal formation. However, the presence of LTP in aged apoE-deficient animals, together with apparent recovery of the PS action on AMPA receptors, suggests that aged apoE-knockout mice possess compensatory mechanisms that reduce biochemical and electrophysiological alterations of glutamatergic neurons.