Preclinical efficacy of potent and selective menin-KMT2A inhibitor JNJ-75276617 in KMT2A- and NPM1-altered leukemias.

The interaction between menin and histone-lysine N-methyltransferase 2A (KMT2A) is a critical dependency for KMT2A- or nucleophosmin 1 (NPM1)-altered leukemias and an emerging opportunity for therapeutic development. JNJ-75276617 is a novel, orally bioavailable, potent, and selective protein-protein interaction inhibitor of the binding between menin and KMT2A. In KMT2A-rearranged (KMT2A-r) and NPM1-mutant (NPM1c) AML cells, JNJ-75276617 inhibited the association of the menin-KMT2A complex with chromatin at target gene promoters, resulting in reduced expression of several menin-KMT2A target genes, including MEIS1 and FLT3. JNJ-75276617 displayed potent anti-proliferative activity across several AML and ALL cell lines and patient samples harboring KMT2A- or NPM1-alterations in vitro. In xenograft models of AML and ALL, JNJ-75276617 reduced leukemic burden and provided a significant dose-dependent survival benefit accompanied by expression changes of menin-KMT2A target genes. JNJ-75276617 demonstrated synergistic effects with gilteritinib in vitro in AML cells harboring KMT2A-r. JNJ-75276617 further exhibited synergistic effects with venetoclax and azacitidine in AML cells bearing KMT2A-r in vitro, and significantly increased survival in mice. Interestingly, JNJ-75276617 showed potent anti-proliferative activity in cell lines engineered with recently discovered mutations (MEN1M327I or MEN1T349M) that developed in patients refractory to the menin-KMT2A inhibitor revumenib. A co-crystal structure of menin in complex with JNJ-75276617 indicates a unique binding mode distinct from other menin-KMT2A inhibitors, including revumenib. JNJ-75276617 is being clinically investigated for acute leukemias harboring KMT2A or NPM1 alterations, as a monotherapy for relapsed/refractory (R/R) acute leukemia (NCT04811560), or in combination with AML-directed therapies (NCT05453903).

Considerations for the Identification and Conveyance of Clinical Pathology Findings in Preclinical Toxicity Studies: Results From the 9th ESTP International Expert Workshop.

The European Society of Toxicologic Pathology (ESTP) organized a panel of 24 international experts from many fields of toxicologic clinical pathology (e.g., industry, academia, and regulatory) that came together in 2021 to align the use of terminology to convey the importance of clinical pathology findings in preclinical toxicity studies. An additional goal consisted of how to identify important findings in standard and nonstandard clinical pathology associated endpoints. This manuscript summarizes the information and opinions discussed and shared at the ninth ESTP International Expert Workshop, April 5 to 6, 2022. In addition to terminology usage, the workshop considered topics related to the identification and conveyance of the importance of test item-related findings. These topics included sources of variability, comparators, statistics, reporting, correlations to other study data, nonstandard biomarkers, indirect/secondary findings, and an overall weight-of-evidence approach.

Evaluation of Novel Urinary Biomarkers in Beagle Dogs With Amphotericin B-Induced Kidney Injury.

Next-generation urinary protein biomarkers have been qualified to enable monitoring for drug-induced kidney injury in toxicology studies conducted in rats. However, there is limited literature on the utility of these biomarkers in dogs. To add to the existing body of knowledge on the utility of the next-generation drug-induced kidney injury (DIKI) biomarkers, we evaluated the value of these biomarkers for the early detection of DIKI in Beagle dogs using a differentiated nephrotoxicant, Amphotericin B (AmpB). In dogs with AmpB-induced kidney injury, we monitored the response of urinary albumin, total protein, clusterin, kidney injury molecule 1, neutrophil gelatinase-associated lipocalin and N-acetyl-beta-D-glucosaminidase. We also measured blood urea nitrogen, serum creatinine and cystatin C. The results showed that urinary clusterin (up to ∼ 112x) was much more sensitive to AmpB-induced kidney injury relative to other biomarkers. Moreover, other than urinary clusterin and to a much lesser extent urinary albumin and total protein, none of the other biomarkers analyzed in this study were more sensitive than blood urea nitrogen and serum creatinine. The AmpB related tubular alterations were characterized by minimal to mild, multifocal necrosis, degeneration, regeneration, dilatation and mineralization. The mild nature of these histopathologic findings further attested to the sensitivity of urinary clusterin to AmpB-induced kidney injury in dogs. These results will help drug developers make informed decisions when selecting urinary biomarkers for monitoring DIKI in dogs for toxicology studies.

Drug-specific T-cell responses in patients with liver injury following treatment with the BACE inhibitor atabecestat.

BACKGROUND: Atabecestat is an orally administered BACE inhibitor developed to treat Alzheimer's disease. Elevations in hepatic enzymes were detected in a number of in trial patients, which resulted in termination of the drug development programme. Immunohistochemical characterization of liver tissue from an index case of atabecestat-mediated liver injury revealed an infiltration of T-lymphocytes in areas of hepatocellular damage. This coupled with the fact that liver injury had a delayed onset suggests that the adaptive immune system may be involved in the pathogenesis. The aim of this study was to generate and characterize atabecestat(metabolite)-responsive T-cell clones from patients with liver injury. METHODS: Peripheral blood mononuclear cells were cultured with atabecestat and its metabolites (diaminothiazine [DIAT], N-acetyl DIAT & epoxide) and cloning was attempted in a number of patients. Atabecestat(metabolite)-responsive clones were analysed in terms of T-cell phenotype, function, pathways of T-cell activation and cross-reactivity with structurally related compounds. RESULTS: CD4+ T-cell clones activated with the DIAT metabolite were detected in 5 out of 8 patients (up to 4.5% cloning efficiency). Lower numbers of CD4+ and CD8+ clones displayed reactivity against atabecestat. Clones proliferated and secreted IFN-γ, IL-13 and cytolytic molecules following atabecestat or DIAT stimulation. Certain atabecestat and DIAT-responsive clones cross-reacted with N-acetyl DIAT; however, no cross-reactivity was observed between atabecestat and DIAT. CD4+ clones were activated through a direct, reversible compound-HLA class II interaction with no requirement for protein processing. CONCLUSION: The detection of atabecestat metabolite-responsive T-cell clones activated via a pharmacological interactions pathway in patients with liver injury is indicative of an immune-based mechanism for the observed hepatic enzyme elevations.

Bilateral Symmetrical Idiopathic Necrotizing Encephalopathy: A New Syndrome in Sprague-Dawley Rats.

This article describes the occurrence of a bilaterally symmetrical encephalopathy in Sprague-Dawley rats, which occurred over the period 2005 to 2012 in our laboratory in both untreated control rats and rats treated with different pharmacologically active compounds. The acute brain lesions consisted of degeneration/necrosis in the ventral areas of the brain mostly with little inflammatory response; in the more rare chronic cases there were numerous lipid-laden macrophages. The areas most consistently affected were the crus cerebri, the ventral midbrain, the pyramids, and the internal capsule. Other areas less frequently affected were the mammillary bodies, the fimbria, the olfactory tubercles, the optic tracts, and the ventral hippocampus. All available data, including clinical signs, gross pathology, clinical pathology, diet, breeding, and housing were collected and are presented. Our investigations did not elucidate the pathogenesis of the lesions, although the infarction-type changes are suggestive of a vascular etiology. To our knowledge, this particular lesion with its consistent distribution pattern has not been reported in the rat literature and its publication is therefore important to the toxicological pathology community, because an unbalanced group distribution in a toxicology study could potentially confound the safety assessment of a compound.

Evaluation of miR-122 and other biomarkers in distinct acute liver injury in rats.

The detection of drug-induced hepatotoxicity remains an important safety issue in drug development. A liver-specific microRNA species, microRNA-122 (miR-122), has recently shown potential for predicting liver injury in addition to the standard hepatic injury biomarkers. The objective of this study was to measure miR-122 together with several other liver markers in distinct settings of acute liver toxicity in rats to determine the value of miR-122 as a biomarker for liver injury in this species. Rats were exposed to 3 well-established liver toxicants (acetaminophen, allyl alcohol, and α-naphthyl isothiocyanate), a liver-enzyme inducer (phenobarbital), or a cardiotoxicant (doxorubicin). There was a clear increase in plasma miR-122 following administration of acetaminophen, allyl alcohol, and α-naphthyl isothiocyanate. The response of miR-122 paralleled that of other markers and was consistent with liver injury as indicated by histopathological evaluation. Furthermore, the changes in miR-122 were detected earlier than standard liver injury markers and exhibited a wide dynamic range. In contrast, miR-122 responses to phenobarbital and doxorubicin were low. Based on these findings, miR-122 shows significant promise and may provide added value for assessing liver toxicity in drug development.

The inhibin B response to the testicular toxicant 1, 3 dinitrobenzene in male rats.

BACKGROUND: This study was conducted as part of an ILSI-HESI International Life Sciences Institute-Health & Environmental Sciences Institute consortium effort to assess the utility of circulating Inhibin B as an early biomarker of Sertoli cell-specific testicular toxicity in rats. 1, 3-Dinitrobenzene (1,3-DNB) was selected as a testicular toxicant in this study as it is known to target Sertoli cells. METHODS: 1,3-DNB (2 and 6 mg/kg/day) or control (corn oil) was administered orally to male rats for two or five consecutive days. Blood was collected from rats treated for 2 days on days 1 and 2 and from rats treated for 5 days on days 1, 3, and 5. The resulting serum was evaluated for Inhibin B and follicle stimulating hormone. At the end of the treatment periods, the testes were removed, weighed, and examined histopathologically. RESULTS: Daily administration of 1,3-DNB resulted in decreased testis weight only on day 5 and only at the high dose (6 mg/kg/day). There was a time-dependent increase in incidence and severity of testicular findings characterized by degeneration of the germinal epithelium with loss of pachytene spermatocytes and vacuolization of the Sertoli cells in the seminiferous tubules at the high dose. Inhibin B levels in 1,3-DNB-treated animals were decreased with treatment only on day 5 at the high dose; there were no associated changes in follicle stimulating hormone. CONCLUSIONS: Changes in serum Inhibin B levels were detected only in association with moderate or severe testicular toxicity as evidenced by histopathology and is therefore considered to be of limited value as a biomarker for Sertoli cell toxicity.

Analytic evaluation of a human ELISA kit for measurement of inhibin B in rat samples.

BACKGROUND: A cross-laboratory analytic evaluation of a commercially available human inhibin B ELISA for measuring inhibin B in rat serum and plasma has been undertaken. METHODS: Dilution linearity, spiked recovery, intra- and inter-assay precision, functional sensitivity, matrix effects, and frozen stability were assessed across five laboratories. Reference ranges were generated for male Sprague Dawley and Han Wistar rats. RESULTS: Acceptable performance was defined as an overall assay coefficient of variation ≤ 20% with an intraday LLOQ ≤ 20 pg/ml. Intra- and inter-assay precision and functional sensitivity (≤6.4 pg/ml) generally met these criteria, but with occasional evidence of greater variability, particularly at lower concentrations. Dilution linearity was acceptable with occasional low recovery. Acceptable recovery of kit calibrators from rat serum confirmed the absence of matrix effects. Matched serum and plasma samples gave comparable results. The signal increased on freezing, remained constant for ≥3 freeze-thaw cycles and was generally stable for at least 8 weeks. Mean inhibin B ranged from 33.5 to 140.6 pg/ml in adult rats across laboratories, with some evidence for a decline from 6 to 9 weeks of age. Power calculations using preliminary reference range data indicated 10 animals/group would generally detect a 40% decrease in inhibin B at AstraZeneca, but laboratories with lower control values would require larger groups. CONCLUSIONS: The assay meets the analytical performance criteria; however, precision at the low end of the standard curve, biological variability, and low control values observed in some laboratories indicate that the utility of the assay may be limited in some laboratories.

Intravenous Administration of Ad26.COV2.S Does Not Induce Thrombocytopenia or Thrombotic Events or Affect SARS-CoV-2 Spike Protein Bioavailability in Blood Compared with Intramuscular Vaccination in Rabbits.

Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a very rare but serious adverse reaction that can occur after Ad26.COV2.S vaccination in humans, leading to thrombosis at unusual anatomic sites. One hypothesis is that accidental intravenous (IV) administration of Ad26.COV2.S or drainage of the vaccine from the muscle into the circulatory system may result in interaction of the vaccine with blood factors associated with platelet activation, leading to VITT. Here, we demonstrate that, similar to intramuscular (IM) administration of Ad26.COV2.S in rabbits, IV dosing was well tolerated, with no significant differences between dosing routes for the assessed hematologic, coagulation time, innate immune, or clinical chemistry parameters and no histopathologic indication of thrombotic events. For both routes, all other non-adverse findings observed were consistent with a normal vaccine response and comparable to those observed for unrelated or other Ad26-based control vaccines. However, Ad26.COV2.S induced significantly higher levels of C-reactive protein on day 1 after IM vaccination compared with an Ad26-based control vaccine encoding a different transgene, suggesting an inflammatory effect of the vaccine-encoded spike protein. Although based on a limited number of animals, these data indicate that an accidental IV injection of Ad26.COV2.S may not represent an increased risk for VITT.

Discovery of an Oral, Beyond-Rule-of-Five Mcl-1 Protein-Protein Interaction Modulator with the Potential of Treating Hematological Malignancies.

Avoidance of apoptosis is critical for the development and sustained growth of tumors. The pro-survival protein myeloid cell leukemia 1 (Mcl-1) is an anti-apoptotic member of the Bcl-2 family of proteins which is overexpressed in many cancers. Upregulation of Mcl-1 in human cancers is associated with high tumor grade, poor survival, and resistance to chemotherapy. Therefore, pharmacological inhibition of Mcl-1 is regarded as an attractive approach to treating relapsed or refractory malignancies. Herein, we disclose the design, synthesis, optimization, and early preclinical evaluation of a potent and selective small-molecule inhibitor of Mcl-1. Our exploratory design tactics focused on structural modifications which improve the potency and physicochemical properties of the inhibitor while minimizing the risk of functional cardiotoxicity. Despite being in the "non-Lipinski" beyond-Rule-of-Five property space, the developed compound benefits from exquisite oral bioavailability in vivo and induces potent pharmacodynamic inhibition of Mcl-1 in a mouse xenograft model.

Tissue Kim-1 and urinary clusterin as early indicators of cisplatin-induced acute kidney injury in rats.

The kidney is one of the main targets of drug toxicity, and early detection of renal damage is critical in preclinical drug development. A model of cisplatin-induced nephrotoxicity in male Sprague Dawley rats treated for 1, 3, 5, 7, or 14 days at 1 mg/kg/day was used to monitor the spatial and temporal expression of various indicators of kidney toxicity during the progression of acute kidney injury (AKI). As early as 1 day after cisplatin treatment, positive kidney injury molecule-1 (Kim-1) immunostaining, observed in the outer medulla of the kidney, and changes in urinary clusterin indicated the onset of proximal tubular injury in the absence of functional effects. After 3 days of treatment, Kim-1 protein levels in urine increased more than 20-fold concomitant with a positive clusterin immunostaining and an increase in urinary osteopontin. Tubular basophilia was also noted, while serum creatinine and blood urea nitrogen levels were elevated only after 5 days, together with tubular degeneration. In conclusion, tissue Kim-1 and urinary clusterin were the most sensitive biomarkers for detection of cisplatin-induced kidney damage. Thereafter, urinary Kim-1 and osteopontin, as well as clusterin immunostaining accurately correlated with the histopathological findings. When AKI is suspected in preclinical rat studies, Kim-1, clusterin, and osteopontin should be part of urinalysis and/or IHC can be performed.

Efferent duct toxicity with secondary testicular changes in rats following administration of a novel leukotriene A4 hydrolase inhibitor.

The efferent ducts represent an important site of toxicity in the male reproductive tract but are not routinely examined in toxicity studies. This article describes a primary efferent duct toxicity that resulted in secondary testicular changes in rats. Male rats were administered LTI-1, a leukotriene A4 hydrolase inhibitor, at doses up to 250 mg/kg/d for 3 month or 150 mg/kg/d for 6 month. At the highest dose levels, testicular changes were predominantly unilateral and characterized by diffuse dilation or atrophy of the seminiferous tubules. These testicular changes correlated with granulomatous inflammation in the corresponding efferent ducts, suggesting that the mechanism for the testicular changes involves obstruction and impaired fluid reabsorption in the efferent ducts. Subsequent buildup in fluid volume and back-pressure upstream of the blockage cause dilation of the seminiferous tubules, which, in its late stages, progress to tubular atrophy. There are important differences in efferent duct anatomy between rats and larger mammals, including humans, such that the latter are less susceptible to testicular injury by this mechanism. Because of the limited relevance of this rat-specific finding to humans, it is important to distinguish testicular changes secondary to efferent duct toxicity from primary drug-induced testicular toxicity.

Discovery and Pharmacological Characterization of JNJ-64619178, a Novel Small-Molecule Inhibitor of PRMT5 with Potent Antitumor Activity.

The protein arginine methyltransferase 5 (PRMT5) methylates a variety of proteins involved in splicing, multiple signal transduction pathways, epigenetic control of gene expression, and mechanisms leading to protein expression required for cellular proliferation. Dysregulation of PRMT5 is associated with clinical features of several cancers, including lymphomas, lung cancer, and breast cancer. Here, we describe the characterization of JNJ-64619178, a novel, selective, and potent PRMT5 inhibitor, currently in clinical trials for patients with advanced solid tumors, non-Hodgkin's lymphoma, and lower-risk myelodysplastic syndrome. JNJ-64619178 demonstrated a prolonged inhibition of PRMT5 and potent antiproliferative activity in subsets of cancer cell lines derived from various histologies, including lung, breast, pancreatic, and hematological malignancies. In primary acute myelogenous leukemia samples, the presence of splicing factor mutations correlated with a higher ex vivo sensitivity to JNJ-64619178. Furthermore, the potent and unique mechanism of inhibition of JNJ-64619178, combined with highly optimized pharmacological properties, led to efficient tumor growth inhibition and regression in several xenograft models in vivo, with once-daily or intermittent oral-dosing schedules. An increase in splicing burden was observed upon JNJ-64619178 treatment. Overall, these observations support the continued clinical evaluation of JNJ-64619178 in patients with aberrant PRMT5 activity-driven tumors.

Hemorrhagic cardiomyopathy in male mice treated with an NNRTI: the role of vitamin K.

Dietary dosing of the non-nucleoside reverse transcriptase inhibitor (NNRTI) TMC125, under development for treatment of HIV-1, resulted in a syndrome in male mice in a previous experiment that was termed hemorrhagic cardiomyopathy. In literature, this syndrome, which was described in rodent species only, was linked to vitamin K deficiency. Two mechanistic studies were conducted, one with dietary administration and a second with gavage. The syndrome was reproduced in only 1 male mouse after continuous dietary dosing, and TMC125 was demonstrated to affect coagulation parameters (prothrombin time [PT], activated partial thromboplastin time [APTT], clotting factors II, VII and XI), particularly in males. This was counteracted by vitamin K supplementation, supporting the hypothesis that the effects were mediated via a vitamin K deficiency. It is therefore concluded that the observed cardiac changes were not caused by a direct cardiotoxic effect but occurred after a state of disabled clotting ability with subsequent effects on mouse cardiac muscle. Therefore, clotting times can be used as adequate safety biomarkers in clinical trials. To date, no changes have been observed at therapeutic doses of TMC125, following human monitoring of PT and APTT. One other NNRTI, Efavirenz (Sustiva), has been reported to cause prolongation of coagulation times in rats and monkeys.

Analytical performance of a commercial multiplex Luminex-based cytokine panel in the rat.

INTRODUCTION: Multiplex immunoassays are an important tool in biomarker research during preclinical drug development. However, information regarding analytical performance of commercial multiplex assays for animal species is often limited. To be able to correctly interpret study results, a fit-for-purpose validation approach is recommended. The objective of our study was to provide a realistic example of what level of validation can be expected from this type of assay, using a rat cytokine panel. METHODS: The analytical performance of a commercial Luminex-based multiplex assay comprising IFN-γ, IL-6, IL-10, IL-12p70, IP-10 and TNF-α was evaluated in Sprague-Dawley rat plasma and serum. Calibration curve, working range, precision, accuracy, selectivity, parallelism, dilutional linearity, prozone effect and sample stability were assessed. RESULTS: Analytical performance in plasma and serum was comparable. Precision and accuracy results for all analytes were acceptable with coefficient of variation (CV) and relative error (RE) often below 15%, except for serum IL-6. Selectivity results varied per analyte with several cytokines showing CV>30% and no single minimum required dilution (MRD) could be identified. In addition, some striking differences between recombinant and endogenous protein results were observed. A pronounced prozone effect was detected for IP-10. Analytes in samples stored at -70°C were stable (RE<30%) from 1 up to 6months depending on the analyte. DISCUSSION: The results illustrate the challenges encountered during validation of commercial animal Luminex-based multiplex assays, revealing analytical limitations such as matrix and prozone effects. The Milliplex rat cytokine panel under investigation was deemed suitable for relative quantification of exploratory type biomarkers.

Renal tubular and adrenal medullary tumors in the 2-year rat study with canagliflozin confirmed to be secondary to carbohydrate (glucose) malabsorption in the 15-month mechanistic rat study.

During preclinical development of canagliflozin, an SGLT2 inhibitor, treatment-related pheochromocytomas, renal tubular tumors (RTT), and testicular Leydig cell tumors were reported in the 2-year rat toxicology study. In a previous 6-month rat mechanistic study, feeding a glucose free diet prevented canagliflozin effects on carbohydrate malabsorption as well as the increase in cell proliferation in adrenal medulla and kidneys, implicating carbohydrate malabsorption as the mechanism for tumor formation. In this chronic study male Sprague-Dawley rats were dosed orally with canagliflozin at high dose-levels (65 or 100 mg/kg/day) for 15 months and received either a standard diet or a glucose-free diet. Canagliflozin-dosed rats on standard diet showed presence of basophilic renal tubular tumors (6/90) and an increased incidence of adrenal medullary hyperplasia (35/90), which was fully prevented by feeding a glucose-free diet (no RTT's; adrenal medullary hyperplasia in ≤5/90). These data further confirm that kidney and adrenal medullary tumors in the 2-year rat study were secondary to carbohydrate (glucose) malabsorption and were not due to a direct effect of canagliflozin on these target tissues.

Chronic drug-induced effects on contractile motion properties and cardiac biomarkers in human induced pluripotent stem cell-derived cardiomyocytes.

BACKGROUND AND PURPOSE: In the pharmaceutical industry risk assessments of chronic cardiac safety liabilities are mostly performed during late stages of preclinical drug development using in vivo animal models. Here, we explored the potential of human induced pluripotent stem cell-derived cardiomyocytes (hiPS-CMs) to detect chronic cardiac risks such as drug-induced cardiomyocyte toxicity. EXPERIMENTAL APPROACH: Video microscopy-based motion field imaging was applied to evaluate the chronic effect (over 72 h) of cardiotoxic drugs on the contractile motion of hiPS-CMs. In parallel, the release of cardiac troponin I (cTnI), heart fatty acid binding protein (FABP3) and N-terminal pro-brain natriuretic peptide (NT-proBNP) was analysed from cell medium, and transcriptional profiling of hiPS-CMs was done at the end of the experiment. KEY RESULTS: Different cardiotoxic drugs altered the contractile motion properties of hiPS-CMs together with increasing the release of cardiac biomarkers. FABP3 and cTnI were shown to be potential surrogates to predict cardiotoxicity in hiPS-CMs, whereas NT-proBNP seemed to be a less valuable biomarker. Furthermore, drug-induced cardiotoxicity produced by chronic exposure of hiPS-CMs to arsenic trioxide, doxorubicin or panobinostat was associated with different profiles of changes in contractile parameters, biomarker release and transcriptional expression. CONCLUSION AND IMPLICATIONS: We have shown that a parallel assessment of motion field imaging-derived contractile properties, release of biomarkers and transcriptional changes can detect diverse mechanisms of chronic drug-induced cardiac liabilities in hiPS-CMs. Hence, hiPS-CMs could potentially improve and accelerate cardiovascular de-risking of compounds at earlier stages of drug discovery. LINKED ARTICLES: This article is part of a themed section on New Insights into Cardiotoxicity Caused by Chemotherapeutic Agents. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.21/issuetoc.

Evaluation of the diagnostic potential of urinary N-Acetyltyramine-O,ß-glucuronide (NATOG) as diagnostic biomarker for Onchocerca volvulus infection.

BACKGROUND: Onchocerciasis, also known as river blindness is one of the neglected tropical diseases affecting millions of people, mainly in sub-Saharan Africa and is caused by the filarial nematode Onchocerca volvulus. Efforts to eliminate this disease are ongoing and are based on mass drug administration programs with the microfilaricide ivermectin. In order to monitor the efficacy of these programs, there is an unmet need for diagnostic tools capable of identifying infected patients. We have investigated the diagnostic potential of urinary N-acetyltyramine-O,ß-glucuronide (NATOG), which is a promising O. volvulus specific biomarker previously identified by urine metabolome analysis. METHODS: A liquid chromatography tandem mass spectrometry (LC-MS/MS) method was used to assess the stability characteristics of NATOG and to evaluate the levels of NATOG in study samples. An LC-fluorescence method was also developed. RESULTS: Stability characteristics of NATOG were investigated and shown to be ideally suited for use in tropical settings. Also, an easy and more accessible method based on liquid chromatography coupled to fluorescence detection was developed and shown to have the necessary sensitivity (limit of quantification 1 µM). Furthermore, we have evaluated the levels of NATOG in a population of 98 nodule-positive individuals from Ghana with no or low levels of microfilaria in the skin and compared them with the levels observed in different control groups (endemic controls (n = 50), non-endemic controls (n = 18) and lymphatic filariasis (n = 51). Only a few (5 %) of nodule-positive individuals showed an increased level (> 10 µM) of NATOG and there was no statistical difference between the nodule-positive individuals and the control groups (P > 0.05). CONCLUSIONS: Results of the present study indicate the limited potential of NATOG as a diagnostic biomarker for O. volvulus infection in amicrofilaridermic individuals.

Cross-laboratory analytical validation of the cardiac biomarker NT-proANP in rat.

INTRODUCTION: Natriuretic peptides, including N-terminal-proatrial natriuretic peptide (NT-proANP) are cardiac hormones that are produced in response to myocardial stretch and have been used in rats and humans as blood based functional cardiac biomarkers. There are limited validation data of these assays in rats and therefore the Predictive Safety Testing Consortium, Cardiac Hypertrophy Working Group (PSTC-CHWG) performed a cross-laboratory (5 laboratories) analytical evaluation of a commercially available NT-proANP ELISA for use with rat samples. METHODS: Serum samples were collected from normal Sprague Dawley (SD) rats and were spiked with kit calibrator material or rat heart tissue extracts to provide specimens for the validation. In addition, the cardiotoxicant, isoproterenol, was used to induce elevated endogenous NT-proANP levels in a subgroup of rats for additional validation specimens. The Biomedica™ (BI-20892, Vienna, Austria) proANP (1-98) enzyme-linked immunoabsorbent assay (ELISA) kit was used to measure NT-proANP. Intra-assay and inter-assay precisions, accuracy, sample linearity, recovery, limit of detection, upper and lower limits of quantitation (ULOQ and LLOQ, respectively), sample-freeze/thaw stability and stored sample stability were assessed and compared to pre-determined acceptance criteria. RESULTS: The majority of the experimental assessments met the established validation criteria, however there were individual results that did not meet these standards. Overall, acceptable intra- and inter-assay precisions and accuracies as well as inter-laboratory precision and accuracy were demonstrated. Linearity and recovery values fell within the pre-determined acceptance criteria, samples remained stable for up to three freeze-thaw cycles and frozen samples were stable at ~-70 °C for 12 months. The limit of detection (LOD) and LLOQ and ULOQ were similar to those specified by the manufacturer. DISCUSSION: Overall, the assay was demonstrated to be technically adequate for the detection of NT-proANP serum levels in SD rats.

Effects of pre-treatment with amantadine on morphine induced antinociception during second phase formalin responses in rats.

The clinically available NMDA-receptor antagonist drug, amantadine, has been shown to result in morphine sparing effects in humans after surgery. However, no data are available to describe the exact form of interaction. The present study aims to profile the possible effects of amantadine (0, 12.5, 25 or 50 mgkg(-1) i.p.) pre-treatment on morphine (0, 0.63, 1.25, 2.5 or 5 mgkg(-1) s.c.) induced antinociception in rats. The (automated) formalin test (5% formalin, 50 microl) was used to assess if amantadine enhances the antinociceptive activity of morphine. Possible motor impairment was assessed with a rotarod test. Morphine was measured in serum of amantadine or vehicle treated rats to search for possible pharmacokinetic interactions between amantadine and morphine. Isobolographic analysis provided evidence for a synergistic interaction between amantadine and morphine in the second phase of the formalin test. No evidence was found to indicate that amantadine induced motor impairment at the doses potentiating morphine during the second phase of the formalin test. There was no evidence for a pharmacokinetic interaction between amantadine and morphine. Since, the second phase of the formalin test is dependent on activation of the NMDA receptor system it is concluded that an antagonistic activity of amantadine at the NMDA receptor most likely contributes to the synergistic interaction observed between amantadine and morphine in rats.