- Email: [email protected]
Long-term performance evaluation of intravascular biopotential leads in telemetered freely moving cynomolgus monkeys
Abstracts
Reverse rate-dependent (RRD) inhibition of the hERG (IKr) channel is a well described characteristic in which greater blockade of ionic current occurs with longer cycle lengths or slower stimulus rates. Similarly, QT/QTc-prolongation by drugs that block IKr is also greater at slower heart rates. Evaluation of RRD QT/QTc-prolongation in vivo requires cardiac pacing or other techniques in order to measure effects over a range of fixed heart rates or RR-intervals. We have recently observed interstudy variability in the magnitude of QTc prolongation in several telemetered nonhuman primate cardiovascular studies in response to the same dose of moxifloxacin (90 mg/kg via oral gavage). Preliminary review of the data indicated that there were differences in Cmax plasma exposures across the studies, and also differences in resting heart rates in the study cohorts. This led to a hypothesis that some of the variability in the response to moxifloxacin may be due to RRD inhibition of IKr. Further analysis of the data shows that studies in animals with slower heart rates had greater increases in both QT and QTc (individual animal-linear correction based on QT-RR slope) compared to studies in animals with faster heart rates. Not surprisingly, studies with higher mean Cmax plasma exposures also had greater degrees of QT/QTc prolongation. This analysis of RRD QT/QTc prolongation with moxifloxacin demonstrates that resting heart rates can impact the relative magnitude of drug-induced QT/QTc prolongation, and that evaluation of drug exposure is also critical to understanding the translation of hERG-mediated effects on cardiac repolarization. doi:10.1016/j.vascn.2013.01.134
129 Development of a nonclinical tool for generating dynamic QT beat-to-beat cloud data Michael Gilla, Geoff Lewena, Lewis Buchanana, William Warnera, Paul Levesqueb a
Bristol-Myers Squibb, Princeton, NJ, USA Bristol-Myers Squibb, Hopewell, NJ, USA
b
Prolongation of the ECG QT interval is a widely-used biomarker for alterations in ventricular repolarization in nonclinical and clinical settings. One method of QT analysis that is gaining clinical popularity examines individual QT–RR pairs from continuous Holter or telemetry data (QT beat-to-beat cloud analysis; QTbtb). We developed a tool for generating translational QTbtb data for beagle dogs and cynomolgus monkeys based on published methods. Our initial objective was to determine if nonclinical QTbtb data could supplement our principle method for evaluating QT interval in dogs and monkeys (QT corrected for heart rate; QTca). The tool was tested with up to 24 h of data at single-beat resolution from up to 16 animals (8/group). In addition, the tool was applied to the existing data from a series of studies with positive and negative control agents in dogs and monkeys. The tool generates descriptive statistics and population distributions for ΔΔQTbtb; 2- and 3-dimensional views of QT/RR clouds; quantile regression for generating upper and lower confidence limits of the QT/ RR clouds; and QT outlier percentages and distributions based on the quantile regression. Additional features include flexible data and subject selection, exportable QTbtb and QT outlier data, and a datamining function to visualize QT/RR sampling across test session plots and cloud plots simultaneously. Results indicate the potential to develop QTbtb data as supplemental nonclinical diagnostic tools to QTca. doi:10.1016/j.vascn.2013.01.135
e37
130 Hemodynamic data analysis — How much is enough? Christopher Douglas, Hilton Jones, Fan Cheung, Mark Osinski Covance Laboratories Inc, Madison, WI, USA There is wide variation in the amount of data used for assessing drug-induced changes in hemodynamic parameters in cardiovascular telemetry studies, and sensitivity to detect significant differences is often discussed without full consensus for what is minimally acceptable. We sought to determine the optimal amount of data analysis that balances the need for accurate and sensitive hemodynamic assessment while reducing the use of time and resources. Eight male Beagle dogs were implanted with DSI® TL11 M3-D70PCTP transmitters and given 10, 30, or 100 mg/kg moxifloxacin by oral gavage in a double Latin square study design. Cardiovascular data were continuously recorded from 90 min predose to 25 h postdose, with additional continuous collections from 47 to 49 and 71 to 73 h postdose. Hourly hemodynamic values (heart rate; systolic, diastolic, and mean arterial pressures; arterial pulse pressure; left ventricular end diastolic pressure; and dP/dtmax) were produced at means of 60, 30, 15, 5, 1, or 0.5 min out of each hour. Hemodynamic data derived by each method were analyzed by analysis of covariance, compared with controls for statistical significance, and evaluated for retrospective statistical power. As the amount of data included in each hourly mean decreased, the variation about the mean increased and statistical power decreased. The overall ability to detect statistically significant differences in hemodynamic values did not change. We conclude that, for the analysis of hemodynamic data, continuous collection and analysis do not offer justifiable improvement in sensitivity over analysis of shorter intervals. doi:10.1016/j.vascn.2013.01.136
131 Long-term performance evaluation of intravascular biopotential leads in telemetered freely moving cynomolgus monkeys Alexis Ascaha, Eric Troncyb, Mylene Pouliota, Simon Authiera,b a
CiToxLAB, Laval, QC, Canada Faculty of Veterinary Medicine, University of Montreal, St-Hyacinthe, QC, Canada
b
Cardiovascular liabilities are the most frequent cause of drug candidate failure. Accuracy of the methodology used to measure cardiovascular parameters is of paramount importance. We previously showed that the biopotential lead placement where the negative lead was inserted in the jugular vein and advanced to the superior vena cava (intravascular lead) and the positive lead placed on the diaphragm at the heart apex (diaphragmatic lead) in cynomolgus monkeys provided reduced signal noise and elevated P–QRS–T amplitudes compared with subcutaneous ECG lead placement. Long-term performance of the methodology was assessed. P– QRS–T amplitudes were recorded from cynomolgus monkeys and reevaluated approximately 10 months later. After a 10 month period, no significant difference in signal amplitude was recorded over time with the intravascular lead and mean amplitude changes of −8.3% and −18% of baseline for R and T waves, respectively. In comparison, mean amplitudes with subcutaneous leads 4 months after implantations were + 32.7% and −17.0% for R and T waves respectively. Amplitude variations during a 24 hour monitoring period with the
e38
Abstracts
intravascular lead were quantified and reached 2×. Our results, suggest that the intravascular lead provides improved signal to noise ratio without significant long term changes. These characteristics of intravascular ECG were associated with improved automated computerized analysis when compared with subcutaneous leads.
doi:10.1016/j.vascn.2013.01.137
132 A new microchip implant for continuous body temperature recording in the rat Elisabeth Patterson, Julie Latour, Florence Lozano, Olivier Perrault, Anna Ponchet-Lac, Florence Pradier, Mohamed Lemallam, Magali Fric-Bordat, Jean-Pierre Martinolle, Ludmilla Mazelin-Winum Sanofi R&D, Montpellier, France Introduction: Body temperature is a critical parameter of CNS assessment in Safety Pharmacology (ICH, S7A) and also helpful in DALA as an important endpoint for identifying withdrawal syndrome. Temperature is most commonly evaluated in rats using either a rectal probe (simple/cost-saving but discontinuous and leading to handling artefact) or classical telemetry (more accurate, continuous but complex/expensive hardware). The aim of this work was to assess the measurement of body temperature using a ThermoTracer, a simple, costless and accurate system that allows the recording of the physiological temperature throughout the animal circadian cycle. Methods: Oceasoft ThermoTracer is a digital battery-powered temperature sensor (Ø:17 mm, 3.3 g) implanted into the peritoneal cavity. It enables continuous recording of core temperature in unrestrained animals with a 0.1 °C precision. At the end of the study, the recorded data are exported to a computer. The implant reliability was assessed using an acute (24 h-temperature profile) or chronic design (withdrawal syndrome after drug cessation, 43-day recording). Results: In controls, normal circadian cycle variations of temperature were observed. Acute chlorpromazine or chronic morphine treatment and its cessation induced important disturbances in body temperature that were in accordance with literature. Post-mortem examination indicated that implants were well tolerated in the peritoneal cavity after a 43-day implantation. Conclusion: We propose a new method of body temperature recording that completes the panel of existing methods. It allows a reliable and continuous measurement of core body temperature in unrestrained rats. This cost-saving system can be used for mid-tolong term studies alone or in combination with other parameters and easily adapted to other species.
doi:10.1016/j.vascn.2013.01.138
133 The potential value of an in vitro hippocampal brain slice assay for the preclinical assessment of seizure liability of anti-infective drugs Alison Easter, Russell Bialecki
Approximately 14% of the marketed drugs associated with seizure clinically are anti-infectives (Murphy and Delanty 2000), only CNStargeted drugs have a higher incidence of seizures. We have described an in vitro brain slice assay for the preclinical assessment of seizure liability (Easter et al., 2007). The aim of this study was to assess the effects of five anti-infectives in this assay and to compare these with any available clinical data. Slices were prepared from C57BL6 mice and evoked population spikes (PS) recorded in the CA1 layer. PS areas (the area above and below the 0 mV line) were calculated in the presence of Penicillin (PC), cefazolin (CZ), enoxacin (EX), imipenem (IP) and aztreonam (AZ), each compound was tested over the concentration range 30–1000 μM. Cumulative concentration-effect curves were generated. PS data (mean ± sem; n = 6–9) were expressed as a % of that in vehicle. Consistent with the profile of a seizurogenic compound, PC, CZ, EX and IP evoked a concentration-dependent increase in PS area. AZ, which has low seizurogenic potential in man, was inactive. For each compound, we compared the active exposure in the brain slice with published values of the efficacious and, where available, seizurogenic exposure in man. For the 4 active compounds, the threshold concentrations for seizurogenic effects in the brain slice assay were all b 5-fold the CNS exposure associated with seizure in man. These data suggest that the hippocampal brain slice may be of value for the preclinical assessment of seizure liability for this class of drugs.
doi:10.1016/j.vascn.2013.01.139
134 Auditory evoked potentials: A feasibility study in telemetered cynomolgus monkeys Simon Authiera,b, Mylene Pouliota, Eric Schaefferc, Sivarao Digavallic, Alexis Ascaha, Eric Troncyb, Michael Weedc a
CIToxLAB North America, Laval, QC, Canada Faculty of Veterinary Medicine, University of Montreal, St-Hyacinthe, QC, Canada c Bristol-Myers Squibb, Wallingford, CT, USA b
Four cynomolgus monkeys were acclimated to a restraint chair and assigned to an auditory evoked potential trial. Through speakers, single tones (e.g. single frequency sine waves) were presented as auditory stimuli to elicit evoked potentials recorded as EEG. These auditory stimuli are innocuous in their intensity (i.e. less than 110 dB, typically 85 dB) and duration (i.e. 50–150 ms). The stimulus intensity was precalibrated by measuring it at the location of the monkeys' ears using a commercially available sound pressure meter. ‘Oddball’ or ‘Mismatch Negativity’ evoked potentials were used: In the oddball paradigm, stimulus trains included two auditory stimuli. One stimulus was presented the majority of the time (standard stimulus: 92%) while the other stimulus (the oddball) was presented randomly and much less frequently (8% of the time). The auditory stimuli included two tones that differed slightly in duration (150 ms and 50 ms length). Stimuli were presented rapidly, with an interstimulus interval of 0.5 s. The methodological process and data analysis confirmed feasibility of the method and its suitability to detect possible effects on the auditory function. Brainstem, middle cortical and late cortical responses were present. This pilot study established procedures for testing auditory evoked potentials in conscious monkeys. doi:10.1016/j.vascn.2013.01.140
AstraZeneca, Waltham, MA, USA
Reverse rate-dependent (RRD) inhibition of the hERG (IKr) channel is a well described characteristic in which greater blockade of ionic current occurs with longer cycle lengths or slower stimulus rates. Similarly, QT/QTc-prolongation by drugs that block IKr is also greater at slower heart rates. Evaluation of RRD QT/QTc-prolongation in vivo requires cardiac pacing or other techniques in order to measure effects over a range of fixed heart rates or RR-intervals. We have recently observed interstudy variability in the magnitude of QTc prolongation in several telemetered nonhuman primate cardiovascular studies in response to the same dose of moxifloxacin (90 mg/kg via oral gavage). Preliminary review of the data indicated that there were differences in Cmax plasma exposures across the studies, and also differences in resting heart rates in the study cohorts. This led to a hypothesis that some of the variability in the response to moxifloxacin may be due to RRD inhibition of IKr. Further analysis of the data shows that studies in animals with slower heart rates had greater increases in both QT and QTc (individual animal-linear correction based on QT-RR slope) compared to studies in animals with faster heart rates. Not surprisingly, studies with higher mean Cmax plasma exposures also had greater degrees of QT/QTc prolongation. This analysis of RRD QT/QTc prolongation with moxifloxacin demonstrates that resting heart rates can impact the relative magnitude of drug-induced QT/QTc prolongation, and that evaluation of drug exposure is also critical to understanding the translation of hERG-mediated effects on cardiac repolarization. doi:10.1016/j.vascn.2013.01.134
129 Development of a nonclinical tool for generating dynamic QT beat-to-beat cloud data Michael Gilla, Geoff Lewena, Lewis Buchanana, William Warnera, Paul Levesqueb a
Bristol-Myers Squibb, Princeton, NJ, USA Bristol-Myers Squibb, Hopewell, NJ, USA
b
Prolongation of the ECG QT interval is a widely-used biomarker for alterations in ventricular repolarization in nonclinical and clinical settings. One method of QT analysis that is gaining clinical popularity examines individual QT–RR pairs from continuous Holter or telemetry data (QT beat-to-beat cloud analysis; QTbtb). We developed a tool for generating translational QTbtb data for beagle dogs and cynomolgus monkeys based on published methods. Our initial objective was to determine if nonclinical QTbtb data could supplement our principle method for evaluating QT interval in dogs and monkeys (QT corrected for heart rate; QTca). The tool was tested with up to 24 h of data at single-beat resolution from up to 16 animals (8/group). In addition, the tool was applied to the existing data from a series of studies with positive and negative control agents in dogs and monkeys. The tool generates descriptive statistics and population distributions for ΔΔQTbtb; 2- and 3-dimensional views of QT/RR clouds; quantile regression for generating upper and lower confidence limits of the QT/ RR clouds; and QT outlier percentages and distributions based on the quantile regression. Additional features include flexible data and subject selection, exportable QTbtb and QT outlier data, and a datamining function to visualize QT/RR sampling across test session plots and cloud plots simultaneously. Results indicate the potential to develop QTbtb data as supplemental nonclinical diagnostic tools to QTca. doi:10.1016/j.vascn.2013.01.135
e37
130 Hemodynamic data analysis — How much is enough? Christopher Douglas, Hilton Jones, Fan Cheung, Mark Osinski Covance Laboratories Inc, Madison, WI, USA There is wide variation in the amount of data used for assessing drug-induced changes in hemodynamic parameters in cardiovascular telemetry studies, and sensitivity to detect significant differences is often discussed without full consensus for what is minimally acceptable. We sought to determine the optimal amount of data analysis that balances the need for accurate and sensitive hemodynamic assessment while reducing the use of time and resources. Eight male Beagle dogs were implanted with DSI® TL11 M3-D70PCTP transmitters and given 10, 30, or 100 mg/kg moxifloxacin by oral gavage in a double Latin square study design. Cardiovascular data were continuously recorded from 90 min predose to 25 h postdose, with additional continuous collections from 47 to 49 and 71 to 73 h postdose. Hourly hemodynamic values (heart rate; systolic, diastolic, and mean arterial pressures; arterial pulse pressure; left ventricular end diastolic pressure; and dP/dtmax) were produced at means of 60, 30, 15, 5, 1, or 0.5 min out of each hour. Hemodynamic data derived by each method were analyzed by analysis of covariance, compared with controls for statistical significance, and evaluated for retrospective statistical power. As the amount of data included in each hourly mean decreased, the variation about the mean increased and statistical power decreased. The overall ability to detect statistically significant differences in hemodynamic values did not change. We conclude that, for the analysis of hemodynamic data, continuous collection and analysis do not offer justifiable improvement in sensitivity over analysis of shorter intervals. doi:10.1016/j.vascn.2013.01.136
131 Long-term performance evaluation of intravascular biopotential leads in telemetered freely moving cynomolgus monkeys Alexis Ascaha, Eric Troncyb, Mylene Pouliota, Simon Authiera,b a
CiToxLAB, Laval, QC, Canada Faculty of Veterinary Medicine, University of Montreal, St-Hyacinthe, QC, Canada
b
Cardiovascular liabilities are the most frequent cause of drug candidate failure. Accuracy of the methodology used to measure cardiovascular parameters is of paramount importance. We previously showed that the biopotential lead placement where the negative lead was inserted in the jugular vein and advanced to the superior vena cava (intravascular lead) and the positive lead placed on the diaphragm at the heart apex (diaphragmatic lead) in cynomolgus monkeys provided reduced signal noise and elevated P–QRS–T amplitudes compared with subcutaneous ECG lead placement. Long-term performance of the methodology was assessed. P– QRS–T amplitudes were recorded from cynomolgus monkeys and reevaluated approximately 10 months later. After a 10 month period, no significant difference in signal amplitude was recorded over time with the intravascular lead and mean amplitude changes of −8.3% and −18% of baseline for R and T waves, respectively. In comparison, mean amplitudes with subcutaneous leads 4 months after implantations were + 32.7% and −17.0% for R and T waves respectively. Amplitude variations during a 24 hour monitoring period with the
e38
Abstracts
intravascular lead were quantified and reached 2×. Our results, suggest that the intravascular lead provides improved signal to noise ratio without significant long term changes. These characteristics of intravascular ECG were associated with improved automated computerized analysis when compared with subcutaneous leads.
doi:10.1016/j.vascn.2013.01.137
132 A new microchip implant for continuous body temperature recording in the rat Elisabeth Patterson, Julie Latour, Florence Lozano, Olivier Perrault, Anna Ponchet-Lac, Florence Pradier, Mohamed Lemallam, Magali Fric-Bordat, Jean-Pierre Martinolle, Ludmilla Mazelin-Winum Sanofi R&D, Montpellier, France Introduction: Body temperature is a critical parameter of CNS assessment in Safety Pharmacology (ICH, S7A) and also helpful in DALA as an important endpoint for identifying withdrawal syndrome. Temperature is most commonly evaluated in rats using either a rectal probe (simple/cost-saving but discontinuous and leading to handling artefact) or classical telemetry (more accurate, continuous but complex/expensive hardware). The aim of this work was to assess the measurement of body temperature using a ThermoTracer, a simple, costless and accurate system that allows the recording of the physiological temperature throughout the animal circadian cycle. Methods: Oceasoft ThermoTracer is a digital battery-powered temperature sensor (Ø:17 mm, 3.3 g) implanted into the peritoneal cavity. It enables continuous recording of core temperature in unrestrained animals with a 0.1 °C precision. At the end of the study, the recorded data are exported to a computer. The implant reliability was assessed using an acute (24 h-temperature profile) or chronic design (withdrawal syndrome after drug cessation, 43-day recording). Results: In controls, normal circadian cycle variations of temperature were observed. Acute chlorpromazine or chronic morphine treatment and its cessation induced important disturbances in body temperature that were in accordance with literature. Post-mortem examination indicated that implants were well tolerated in the peritoneal cavity after a 43-day implantation. Conclusion: We propose a new method of body temperature recording that completes the panel of existing methods. It allows a reliable and continuous measurement of core body temperature in unrestrained rats. This cost-saving system can be used for mid-tolong term studies alone or in combination with other parameters and easily adapted to other species.
doi:10.1016/j.vascn.2013.01.138
133 The potential value of an in vitro hippocampal brain slice assay for the preclinical assessment of seizure liability of anti-infective drugs Alison Easter, Russell Bialecki
Approximately 14% of the marketed drugs associated with seizure clinically are anti-infectives (Murphy and Delanty 2000), only CNStargeted drugs have a higher incidence of seizures. We have described an in vitro brain slice assay for the preclinical assessment of seizure liability (Easter et al., 2007). The aim of this study was to assess the effects of five anti-infectives in this assay and to compare these with any available clinical data. Slices were prepared from C57BL6 mice and evoked population spikes (PS) recorded in the CA1 layer. PS areas (the area above and below the 0 mV line) were calculated in the presence of Penicillin (PC), cefazolin (CZ), enoxacin (EX), imipenem (IP) and aztreonam (AZ), each compound was tested over the concentration range 30–1000 μM. Cumulative concentration-effect curves were generated. PS data (mean ± sem; n = 6–9) were expressed as a % of that in vehicle. Consistent with the profile of a seizurogenic compound, PC, CZ, EX and IP evoked a concentration-dependent increase in PS area. AZ, which has low seizurogenic potential in man, was inactive. For each compound, we compared the active exposure in the brain slice with published values of the efficacious and, where available, seizurogenic exposure in man. For the 4 active compounds, the threshold concentrations for seizurogenic effects in the brain slice assay were all b 5-fold the CNS exposure associated with seizure in man. These data suggest that the hippocampal brain slice may be of value for the preclinical assessment of seizure liability for this class of drugs.
doi:10.1016/j.vascn.2013.01.139
134 Auditory evoked potentials: A feasibility study in telemetered cynomolgus monkeys Simon Authiera,b, Mylene Pouliota, Eric Schaefferc, Sivarao Digavallic, Alexis Ascaha, Eric Troncyb, Michael Weedc a
CIToxLAB North America, Laval, QC, Canada Faculty of Veterinary Medicine, University of Montreal, St-Hyacinthe, QC, Canada c Bristol-Myers Squibb, Wallingford, CT, USA b
Four cynomolgus monkeys were acclimated to a restraint chair and assigned to an auditory evoked potential trial. Through speakers, single tones (e.g. single frequency sine waves) were presented as auditory stimuli to elicit evoked potentials recorded as EEG. These auditory stimuli are innocuous in their intensity (i.e. less than 110 dB, typically 85 dB) and duration (i.e. 50–150 ms). The stimulus intensity was precalibrated by measuring it at the location of the monkeys' ears using a commercially available sound pressure meter. ‘Oddball’ or ‘Mismatch Negativity’ evoked potentials were used: In the oddball paradigm, stimulus trains included two auditory stimuli. One stimulus was presented the majority of the time (standard stimulus: 92%) while the other stimulus (the oddball) was presented randomly and much less frequently (8% of the time). The auditory stimuli included two tones that differed slightly in duration (150 ms and 50 ms length). Stimuli were presented rapidly, with an interstimulus interval of 0.5 s. The methodological process and data analysis confirmed feasibility of the method and its suitability to detect possible effects on the auditory function. Brainstem, middle cortical and late cortical responses were present. This pilot study established procedures for testing auditory evoked potentials in conscious monkeys. doi:10.1016/j.vascn.2013.01.140
AstraZeneca, Waltham, MA, USA