Longitudinal studies of cardiac troponin I concentrations in serum from male cynomolgus monkeys: resting values and effects of oral and intravenous dosing on biologic variability

Abstract

Background: There is a paucity of information regarding cardiac troponin (cTn) concentrations in peripheral blood of nonhuman primates (NHP). Even less is known regarding cTn concentrations in monkeys that are restrained for oral or intravenous (iv) dosing. Objectives: The objectives of these studies were to (1) determine cardiac troponin I (cTnI) concentration in resting Cynomolgus monkeys and investigate biologic variability in cTnI concentration over time, (2) determine cTnI changes in restrained monkeys given sham oral dosing, and (3) determine cTnI changes in restrained NHP given a sham intravenous dosing. Methods: The Research Use Only Erenna cTnI ultrasensitive immunoassay based on single molecule counting technology was used to determine serum cTnI concentration in longitudinal studies of male Cynomolgus monkeys at rest, and after sham oral and intravenous dosing. Animals were catheterized prestudy, and blood samples were collected by an automated sampling device to limit disturbance of the animals during studies. Results: In resting monkeys cTnI concentrations were relatively low and constant and ranged from 0.2 to 9.6 pg/mL (mean = 2.5 pg/mL), with minimal variability during a 24-hour period. Animals given sham oral dosing also had low cTnI concentration with little variability similar to the resting values. Several animals restrained for intravenous dosing had a small transient increase in cTnI concentration (~5-25 pg/mL) that resolved quickly within one to 3 hours postinjection. Conclusions: Results of this longitudinal study provide information that may be important in differentiating effects of animal handling from those associated with compound-related effects in preclinical toxicology studies of drugs in development.

Assessment of Cardiac Troponin I Responses in Nonhuman Primates during Restraint, Blood Collection, and Dosing in Preclinical Safety Studies

“…Skeletal muscle injury is further supported in the animal with an elevation in CK values on day 1 prior to dosing, without concurrent increase in cTnI concentrations. Schultze et al (2015) have performed similar experiments to those discussed above. They looked at cTnI concentrations in resting NHP as well as those that had been shamed dosed by oral gavage or intravenous saline injection.…”

“…Other potential mechanisms that have been suggested that can lead to the release of troponin without necrosis include apoptosis, normal myocyte turnover, cellular release of proteolytic troponin degradation products, increased cellular wall permeability, or formation and release of membranous blebs (White 2011). This is further supported by the very low fluctuating levels of cTnI that can be detected in the circulation of normal animals using the newer ultrasensitive assays such as the Singulex Errena cTnI (Schultze et al 2015(Schultze et al , 2009. Although these mechanisms for release of cardiac troponin from intact cells cannot be totally ruled out, minimal myocellular necrosis leading to transient elevation of cardiac troponin also cannot be ruled out.…”

“…Preanalytical variables including site of collection, quality of the samples, and timing of the sampling, as well as methods of restraint and blood sample collection are also critical factors for accurate assessment of a cardiac troponin response, especially in NHP studies. A recent publication using the Singulex Errena ultrasensitive cTnI assay showed that restraint associated with sham oral and intravenous dosing in cynomolgus macaques induced a transient elevation in cTnI (Schultze et al 2015). The purpose of this publication is to further characterize the effect of restraint in cynomolgus macaques on the cTnI results using the Siemens Immulite cTnI and the Siemens Troponin I-Ultra assays.…”

“…In 2012, cTnI was qualified by the FDA as a marker of cardiac necrosis in rats and dogs for use in preclinical studies (Woodcock 2012). At the time the qualification document was submitted in late 2008, there were limited published studies demonstrating the use of this biomarker in nonhuman primates (NHP) studies, although more recently, additional publications have become available (Dunn et al 2012; Minomo et al 2009; Schultze et al 2015; Takeuchi et al 2008; Zabka, Irwin, and Albassam 2009). Based on the paucity of published information on the use of this biomarker in NHP at the time of submission, cTnI was not officially qualified for use in NHP.…”

Effects of repeated restraint and blood sampling with needle injection on blood cardiac troponins in rats, dogs, and cynomolgus monkeys

“…Schultze et al previously reported blood cTnI measurements in intact Sprague-Dawley rats and cynomolgus monkeys. Their experiments consisted of careful measurements made over multiple time points under resting conditions after saline administration by oral gavage (Schultze et al 2009 , 2015 ). Although these studies provided much-needed data for future cTnI research, serial blood samplings were conducted using an automated cannulation method, which is different from the standard procedures of most toxicity studies (i.e., repeated needle injections under restraint).…”