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.

Time course characterization of serum cardiac troponins, heart fatty acid-binding protein, and morphologic findings with isoproterenol-induced myocardial injury in the rat.

We investigated the kinetics of circulating biomarker elevation, specifically correlated with morphology in acute myocardial injury. Male Hanover Wistar rats underwent biomarker and morphologic cardiac evaluation at 0.5 to seventy-two hours after a single subcutaneous isoproterenol administration (100 or 4000 microg/kg). Dose-dependent elevations of serum cardiac troponins I and T (cTnI, cTnT), and heart fatty acid-binding protein (H-FABP) occurred from 0.5 hour, peaked at two to three hours, and declined to baseline by twelve hours (H-FABP) or forty-eight to seventy-two hours (Serum cTns). They were more sensitive in detecting cardiomyocyte damage than other serum biomarkers. The Access 2 platform, an automated chemiluminescence analyzer (Beckman Coulter), showed the greatest cTnI fold-changes and low range sensitivity. Myocardial injury was detected morphologically from 0.5 hour, correlating well with loss of cTnI immunoreactivity and serum biomarker elevation at early time points. Ultrastructurally, there was no evidence of cardiomyocyte death at 0.5 hour. After three hours, a clear temporal disconnect occurred: lesion scores increased with declining cTnI, cTnT, and H-FABP values. Serum cTns are sensitive and specific markers for detecting acute/active cardiomyocyte injury in this rat model. Heart fatty acid-binding protein is a good early marker but is less sensitive and nonspecific. Release of these biomarkers begins early in myocardial injury, prior to necrosis. Assessment of cTn merits increased consideration for routine screening of acute/ongoing cardiomyocyte injury in rat toxicity studies.

Correlation of serum cardiac troponin I and acute phase protein concentrations with clinical staging in dogs with degenerative mitral valve disease.

BACKGROUND: Cardiac troponin I (cTnI) correlates with severity of myocardial injury. Nonspecific inflammation in congestive heart failure (CHF) could be assessed by C-reactive protein (CRP), haptoglobin (Hp), and ceruloplasmin (Cp) measurements. OBJECTIVES: The aim of the study was to determine whether serum cTnI, CRP, Hp, and Cp concentrations differ among various stages of mitral valve disease (MVD) in dogs. MATERIALS AND METHODS: Dogs with MVD were allocated to 3 groups (I - asymptomatic; II - mild to moderate CHF; III advanced CHF) according to the scheme of the International Small Animal Cardiac Healthy Council (ISACHC). Concentrations of cTnI, CRP, Cp, and Hp were measured in all dogs upon admission, and cTnI and CRP were measured bimonthly during a 4-month follow-up period. RESULTS: In total 46 dogs with MVD were enrolled for the cross-sectional part (21 Group I, 11 Group II, 14 Group III), and 35 dogs were included in the longitudinal study. Initial mean Cp concentrations were similar among all groups. There was a statistically significant difference in Hp and CRP concentrations between group I (n = 21, P = .019) and III (n = 14, P < .001). There was a statistically significant decrease in CRP (P = .033) and cTnI (P = .009) concentrations over the longitudinal study (all groups). CRP concentrations were significantly higher in group I than III (P = .004). During the 6-month monitoring period of 35 dogs, there was a statistically significant positive correlation between cTnI and CRP (P < .001). CONCLUSION: Differences in CRP concentrations between clinical stages of MVD suggest a clinically and therapeutically relevant inflammatory component.

Serial analysis of serum cardiac troponin I changes and correlation with clinical findings in 46 dogs with mitral valve disease.

BACKGROUND: Cardiac troponin I (cTnI) is a biomarker correlated with the severity of myocardial injury. It is hypothesized that serial assessment of cTnI could provide information about the disease progression in chronic heart failure. OBJECTIVE: The purpose of the study was to correlate serial serum cTnI concentrations with clinical scoring and select diagnostic imaging findings in dogs managed for mitral valve degeneration (MVD) for a period of 6 months. METHODS: Client-owned dogs with MVD were prospectively recruited for the study. The dogs were allocated into 3 groups (I, II, III) according to the severity of their clinical signs based on the classification suggested by the International Small Animal Cardiac Health Council. During the 6-month study period, serum specimens for biochemical testing were obtained biweekly, clinical progression and response to treatment were also evaluated biweekly, and radiographic reevaluation was performed every 2 months. RESULTS: A total of 46 dogs were evaluated. There was a marked decrease in cTnI values during the first 2 weeks after initial diagnosis, more pronounced in group III, and corresponding to the initiation of therapy and clinical stabilization of animals. Serum cTnI was significantly different (P < .05) among the 3 dog groups throughout the study period. The interaction between Group and Period was significant in group III, indicating an upward cTnI trend evident in severely affected animals. A positive correlation was demonstrated in all groups between serum cTnI and clinical scoring. CONCLUSION: Long-term management of MVD in dogs could benefit from the serial measurement of cTnI.