A. Eric Schultze

Ultrasensitive Cross-species Measurement of Cardiac Troponin-I Using the Erenna Immunoassay System

Serum cardiac troponin-I (cTnI) has been validated as a biomarker for cardiotoxicity in numerous animal models; however, owing to sensitivity issues cTnI concentrations in healthy, resting animals used in toxicology studies have not been established. Serum from healthy and isoproterenol hydrochloride (iso)-treated rats, dogs, and monkeys were assayed using the Erenna system. The Erenna cTnI assay provided sensitivity < 1 ng/L across human, rat, dog, and monkey cTnI. Linear responses (R 2= 0.99) were observed for all species. Precision studies yielded interassay CVs of curve fit quantification from 2% to 4% between 1.6 and 5000 ng/L, and 23% at 0.78 ng/L. Strong correlation (R 2= 0.99) was obtained between Erenna and Beckman Access cTnI. Concentrations of cTnI in healthy animals ranged from 1 to 9 ng/L. In longitudinal studies of iso-treated animals, the concentrations of cTnI in the control vehicle-treated groups were 10–20 ng/L for rats (N = 10) and predose values of 2–3 ng/L for dogs (N = 3). Measured with the Erenna assay system, cTnI was quantifiable at all time intervals tested in all animals treated with iso. The Erenna system provides sensitive measurement of cTnI in rats, dogs, and monkeys, makes it possible to determine small changes from normal concentrations, and provides cTnI values from small volumes of serum.

Longitudinal Studies of Cardiac Troponin-I Concentrations in Serum from Male Sprague Dawley Rats: Baseline Reference Ranges and Effects of Handling and Placebo Dosing on Biological Variability

Serum cardiac troponin-I has been validated as a biomarker for cardiotoxicity in numerous animal models; however, baseline reference ranges for cTnI concentration in a healthy population of laboratory rats, as well as an investigation of biological cTnI variability in rats with respect to time, handling, and placebo dosing methods, have not been reported. In this study, we used an ultrasensitive cTnI immunoassay to quantify hourly concentrations of cTnI in live rats handled under standard laboratory conditions using 15 μL of serum per determination. The baseline reference range (mean 4.94 pg/mL, range 1–15 pg/mL, 99% confidence interval [CI]) of cTnI concentration in rats was consistent with previously reported reference ranges for cTnI in humans (1–12 pg/mL) and with preliminary studies in dogs (1–4 pg/mL) and monkeys (4–5 pg/mL) using the same cTnI assay method. In addition, cTnI concentrations in individual rat serum samples show minimal biological variability over a twenty-four-hour interval when compared to a meaningful reference change value of 193% to 206%. Furthermore, measurements of cTnI concentration were consistent within the reference limits in individual rats over long periods and under three different standard laboratory handling conditions. Thus, using this new method, rats can be followed longitudinally at hourly intervals, and a doubling of cTnI concentration would be significant above biological variability. This is a new paradigm for preclinical testing, which allows transient changes in cTnI concentration to be accurately quantified. This understanding of baseline and biological variability in rats will be fundamental for designing and analyzing future studies that assess potential cardiotoxicity in drug development.

Qualification of Cardiac Troponin I Concentration in Mouse Serum Using Isoproterenol and Implementation in Pharmacology Studies to Accelerate Drug Development

Cardiac troponin I is a useful biomarker of myocardial injury, but its use in mice and application to early drug discovery are not well described. The authors investigated the relationship between cTnI concentration in serum and histologic lesions in heart tissue from mice treated with isoproterenol (ISO). Cardiac TnI concentrations in serum increased in a dose-dependant manner and remained increased twenty-four to forty-eight hours after a single administration of isoproterenol. Increased cTnI concentration was of greater magnitude and longer duration than increased fatty acid binding protein 3 concentration, aspartate aminotransferase activity, and creatine kinase activity in serum. Isoproterenol-induced increases in cTnI concentrations were both greater and more sustained in BALB/c than in CD1 mice and correlated with incidence and severity of lesions observed in heart sections from both strains. In drug development studies in BALB/c mice with novel kinase inhibitors, cTnI concentration was a reliable stand-alone biomarker of cardiac injury and was used in combination with measurements of in vivo target inhibition to demonstrate an off-target contribution to cardiotoxicity. Additional attributes, including low cost and rapid turnaround time, made cTnI concentration in serum invaluable for detecting cardiotoxicity, exploring structure–activity relationships, and prioritizing development of compounds with improved safety profiles early in drug discovery.

A public-private consortium advances cardiac safety evaluation: achievements of the HESI Cardiac Safety Technical Committee.

INTRODUCTION The evaluation of cardiovascular side-effects is a critical element in the development of all new drugs and chemicals. Cardiac safety issues are a major cause of attrition and withdrawal due to adverse drug reactions (ADRs) in pharmaceutical drug development. METHODS The evolution of the HESI Technical Committee on Cardiac Safety from 2000-2013 is presented as an example of an effective international consortium of academic, government, and industry scientists working to improve cardiac safety. RESULTS AND DISCUSSION The HESI Technical Committee Working Groups facilitated the development of a variety of platforms for resource sharing and communication among experts that led to innovative strategies for improved drug safety. The positive impacts arising from these Working Groups are described in this article.

Veterinary clinical pathologists in the biopharmaceutical industry

There is an international shortage of veterinary clinical pathologists in the workplace. Current trainees in veterinary clinical pathology may choose to pursue careers in academe, diagnostic laboratories, government health services, biopharmaceutical companies, or private practice. Academic training programs attempt to provide trainees with an exposure to several career choices. However, due to the proprietary nature of much of the work in the biopharmaceutical industry, trainees may not be fully informed regarding the nature of work for veterinary clinical pathologists and the myriad opportunities that await employment in the biopharmaceutical industry. The goals of this report are to provide trainees in veterinary clinical pathology and other laboratory personnel with an overview of the work-life of veterinary clinical pathologists employed in the biopharmaceutical industry, and to raise the profile of this career choice for those seeking to enter the workforce. Biographical sketches, job descriptions, and motivation for 3 successful veterinary clinical pathologists employed in the biopharmaceutical industry are provided. Current and past statistics for veterinary clinical pathologists employed in the biopharmaceutical industry are reviewed. An overview of the drug development process and involvement of veterinary clinical pathologists in the areas of discovery, lead optimization, and candidate evaluation are discussed. Additional duties for veterinary clinical pathologists employed in the biopharmaceutical industry include development of biomarkers and new technologies, service as scientific resources, diagnostic support services, and laboratory management responsibilities. There are numerous opportunities available for trainees in veterinary clinical pathology to pursue employment in the biopharmaceutical industry and enjoy challenging and rewarding careers.

A Comparison of Mortality and Cardiac Biomarker Response between Three Outbred Stocks of Sprague Dawley Rats Treated with Isoproterenol

The authors compared the mortality and cardiac biomarker responses in three outbred stocks of Sprague Dawley rats (CD/IGS, Sasco, Harlan) treated with isoproterenol hydrochloride. Cardiac injury was confirmed by histologic evaluation, and increases in cardiac troponin I concentration in serum were measured by two methods. CD/IGS rats had a higher incidence and earlier mortality compared with Sasco or Harlan rats. Harlan rats had lower severity scores for cardiomyocyte degeneration/necrosis compared with the other stocks. Post–isoproterenol treatment cardiac troponin I concentrations were greater in CD/IGS and Sasco rats compared with Harlan rats. Concentrations of cardiac troponin T followed a similar pattern to that of cardiac troponin I in rats treated with isoproterenol. Myosin, light chain 3 concentrations increased in all rats treated with isoproterenol, but there was no difference between the three stocks in the magnitude or pattern of the dose response. Increases in fatty acid binding protein 3 concentrations were detected in only the highest dose group at the earliest timepoint postdose for all three stocks of rats. Results of these studies illustrate the need for investigators to recognize the potential differences in response between stocks of Sprague Dawley rats treated with cardiotoxicants or novel chemical entities.

Current Practices in Preclinical Drug Development Gaps in Hemostasis Testing to Assess Risk of Thromboembolic Injury

The Health and Environmental Sciences Institute Cardiac Biomarkers Working Group surveyed the pharmaceutical development community to investigate practices in assessing hemostasis, including detection of hypocoagulable and hypercoagulable states. Scientists involved in discovery, preclinical, and clinical research were queried on laboratory evaluation of endothelium, platelets, coagulation, and fibrinolysis during safety assessment studies. Results indicated that laboratory assessment of hemostasis is inconsistent among institutions and not harmonized between preclinical and clinical studies. Hemostasis testing in preclinical drug safety studies primarily focuses on the risk of bleeding, whereas the clinical complication of thrombosis is seldom assessed. Our results reveal the need for broader utilization of biomarkers to detect altered hemostasis (e.g., endothelial and platelet activation) to improve preclinical safety assessments early in the drug development process. Survey respondents indicated a critical lack of validated markers of hypercoagulability and subclinical thrombosis in animal testing. Additional obstacles included limited blood volume, lack of cross-reacting antibodies for hemostasis testing in laboratory species, restricted availability of specialized hemostasis analyzers, and few centers of expertise in animal hemostasis testing. Establishment of translatable biomarkers of prothrombotic states in multiple species and strategic implementation of testing on an industry-wide basis are needed to better avert untoward drug complications in patient populations.

Estimating leukocyte, platelet, and erythrocyte counts in rats by blood smear examination

BACKGROUND The CBC is an essential test for assessing the health of rats used in drug development studies. Because of limited blood volume, estimates of cell counts from a blood smear would be valuable when other analytical methods of enumerating cells are not possible or available. OBJECTIVE The purpose of this study was to develop a statistical model to accurately estimate WBC, platelet (PLT), and RBC counts in blood smears from rats. METHOD Blood smears and quantitative cell counts were obtained from vehicle-treated male and female Fischer 344 rats (n=65) involved in a variety of studies. The numbers of WBCs, PLTs, and RBCs were estimated in 10 fields in the monolayer of smears using x 20 (WBC) or x 100 (PLT, RBC) objectives. Using a statistical model and the quantitative cell counts obtained on an ADVIA 120 hematology analyzer, formulas were developed to predict the quantitative counts from the estimates. RESULTS Data were log-transformed before analysis. A formula was derived using the slope and intercept of the regression line between cell estimates and ADVIA counts to predict WBC, PLT, and RBC counts based only on estimates. A second formula was developed for situations in which limited quantitative analyses may be available, and resulted in even more accurately predicted counts from smear estimates. CONCLUSION The formulas developed in this study can be a valuable tool in estimating cell counts from a blood smear when cell counting instruments are not available or when an instrument cell count needs to be verified. These formulas may be useful in the assessment of rat blood in discovery and lead optimization studies.

Nonclinical pharmacology and toxicology of the first biosimilar insulin glargine drug product (BASAGLAR®/ABASAGLAR®) approved in the European Union

ABSTRACT Basaglar®/Abasaglar® (Lilly insulin glargine [LY IGlar]) is a long‐acting human insulin analogue drug product granted marketing authorisation as a biosimilar to Lantus® (Sanofi insulin glargine [SA IGlar]) by the European Medicines Agency. We assessed the similarity of LY IGlar to the reference drug product, European Union–sourced SA IGlar (EU‐SA IGlar), using nonclinical in vitro and in vivo studies. No biologically relevant differences were observed for receptor binding affinity at either the insulin or insulin‐like growth factor‐1 (IGF‐1) receptors, or in assays of functional or de novo lipogenic activity. The mitogenic potential of LY IGlar and EU‐SA IGlar was similar when tested in both insulin‐ and IGF‐1 receptor dominant cell systems. Repeated subcutaneous daily dosing of rats for 4 weeks with 0, 0.3, 1.0, or 2.0 mg/kg LY IGlar and EU‐SA IGlar produced mortalities and clinical signs consistent with severe hypoglycaemia. Glucodynamic profiles of LY IGlar and EU‐SA IGlar in satellite animals showed comparable dose‐related hypoglycaemia. Severe hypoglycaemia was associated with axonal degeneration of the sciatic nerve; the incidence and severity were low and did not differ between LY IGlar and EU‐SA IGlar. These results demonstrated no biologically relevant differences in toxicity between LY IGlar and EU‐SA IGlar. HIGHLIGHTSBasaglar®/Abasaglar® (LY IGlar) is the first biosimilar insulin glargine drug product approved in the European Union.We compared nonclinical profiles of LY IGlar and European Union–sourced Lantus (EU‐SA IGlar).We found no biologically relevant differences between LY IGlar and EU‐SA IGlar.

Deciphering Sources of Variability in Clinical Pathology It’s Not Just about the Numbers

The objectives of this session were to explore causes of variability in clinical pathology data due to preanalytical and analytical variables as well as study design and other procedures that occur in toxicity testing studies. The presenters highlighted challenges associated with such variability in differentiating test article–related effects from the effects of experimental procedures and its impact on overall data interpretation. These presentations focused on preanalytical and analytical variables and study design–related factors and their influence on clinical pathology data, and the importance of various factors that influence data interpretation including statistical analysis and reference intervals. Overall, these presentations touched upon potential effect of many variables on clinical pathology parameters, including animal physiology, sample collection process, specimen handling and analysis, study design, and some discussion points on how to manage those variables to ensure accurate interpretation of clinical pathology data in toxicity studies. This article is a brief synopsis of presentations given in a session entitled “Deciphering Sources of Variability in Clinical Pathology—It’s Not Just about the Numbers” that occurred at the 35th Annual Symposium of the Society of Toxicologic Pathology in San Diego, California.