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Cardiac Ion Channel Safety Profiling: hERG and beyond G Erdemli Novartis Institutes for Biomedical Research PowerPoint Presentation
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Cardiac Ion Channel Safety Profiling: hERG and beyond G Erdemli Novartis Institutes for Biomedical Research. Summary. Introduction to preclinical cardiac ion channel safety profiling Overview of automated electrophysiology technologies used at Novartis QPatch 16, HT & HTX IonWorks Quattro

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Cardiac Ion Channel Safety Profiling: hERG and beyondG ErdemliNovartis Institutes for Biomedical Research

summary
Summary
  • Introduction to preclinical cardiac ion channel safety profiling
  • Overview of automated electrophysiology technologies used at Novartis
    • QPatch 16, HT & HTX
    • IonWorks Quattro
    • IonFlux 16 microfluidics system
  • Cardiac ion channel in vitro assays and case studies
    • hERG, Nav1.5, Cav1.2 and KCNQ1/minK
  • Implementation of preclinical in vitro ion channel safety profiling in the integrated risk assessment for cardiac safety
  • Indirect ion channel modulation, potential mechanisms and implications in preclinical safety assessment

G Erdemli, Ion Channel Retreat, Vancouver, June 28-30 2010

ecg and action potential repolarization cardiac ion channel profiling cardiac risk assessment

Ito (hKv 4.2 hKv 4.3)

1

IKs

(hminK + hKvLQT1)

IKr

(KvHERG+hMiRP)

QT interval

3

INa

0

2

R

ICa

T

IK1 (hKIR)

P

RMP -80/90 mV

Q

S

ECG and action potential repolarizationCardiac ion channel profiling cardiac risk assessment

Repolarization

reserve

LQT

+25 mV

-0 mV

G Erdemli, Ion Channel Retreat, Vancouver, June 28-30 2010

genetic basis for lqts
Genetic basis for LQTS

(hERG)

Kaufman. Heart rhythm 2009 vol. 6 (8 Suppl) pp. S51-5

Schwartz et al Circulation 2001

G Erdemli, Ion Channel Retreat, Vancouver, June 28-30 2010

cardiac ion channel safety profiling herg on qpatch ht
Cardiac ion channel safety profiling hERG on Qpatch-HT
  • Routine hERG screening on QPatch-HT
  • 6 pnt CRC, n=3
  • 70% success rate (completed experiments)

G Erdemli, Ion Channel Retreat, Vancouver, June 28-30 2010

high quality and reproducible results on qpatch ht
High quality and reproducible results on QPatch-HT

G Erdemli, Ion Channel Retreat, Vancouver, June 28-30 2010

qpatch data analysis reaching equilibrium
QPatch data analysis: Reaching equilibrium

G Erdemli, Ion Channel Retreat, Vancouver, June 28-30 2010

herg openers
hERG Openers

During routine screening hERG channel enhancers from different chemical series are identified

Incorporated into automated data analysis for alerts

G Erdemli, Ion Channel Retreat, Vancouver, June 28-30 2010

effects of temperature in drug induced herg inhibition
Effects of temperature in drug-induced hERG inhibition

22°C

35°C

G Erdemli, Ion Channel Retreat, Vancouver, June 28-30 2010

herg current on ionflux 16 automated patch clamp at physiological temperatures
hERG current on IonFlux-16Automated patch clamp at physiological temperatures

A.

C D

G Erdemli, Ion Channel Retreat, Vancouver, June 28-30 2010

cardiac ion channel safety profiling nav1 5 assay on ionworks quattro
Cardiac ion channel safety profiling Nav1.5 assay on IonWorks Quattro

Raw traces pre-cpd

Normalized current post-cpd

QC Monitor for seals

  • 8 pnt CRC, n=4
  • ~100% success rate
  • Use-dependency

Multi-state IC50 determination

Use-dependence Characterization

G Erdemli, Ion Channel Retreat, Vancouver, June 28-30 2010

hnav1 5 pharmacology on quattro
hNav1.5 Pharmacology on Quattro

Manual patch clamp

from literature

G Erdemli, Ion Channel Retreat, Vancouver, June 28-30 2010

compound 1 an example of translational value of hnav1 5 assay
Compound 1 An example of translational value of hNav1.5 assay
  • Preclinical cardiosafety data
    • in vitro Nav1.5 IC50 = 15.4 mM
    • Dose dependent prolongation of P, PQ and QRS in dog telemetry, no/minimal QT interval prolongation
    • Sudden deaths in 13 week dog toxicity study & polymorphic ventricular tachycardia - consistent with an extreme sodium channel inhibition, with PR prolongation as the first sign
  • Clinical cardiosafety data
    • Compound 1 at 640 mg (single dose) caused PR interval prolongation that coincided with the Tmax of the drug’s plasma concentration. NOEL = 1.72 mM (320 mg/kg)
  • Clinical studiesstudies terminated due to risk of cardiac conduction abnormalities
    • Therapeutic margin < 0.8 for PR prolongation

G Erdemli, Ion Channel Retreat, Vancouver, June 28-30 2010

compound 1 preclinical cardiac safety data dog
Compound 1 Preclinical Cardiac Safety Data (Dog)
  • IV/IV Index50: In vitro/In vivo Index: Nav1.5 IC50/Free CMax
  • IV/IV Index20: In vitro/In vivo Index: Nav1.5 IC20/Free Cmax

G Erdemli, Ion Channel Retreat, Vancouver, June 28-30 2010

compound 1 clinical cardiac safety data
Compound 1 Clinical Cardiac Safety Data

NC: No change

G Erdemli, Ion Channel Retreat, Vancouver, June 28-30 2010

compound 1 sad 320mg 640mg maximum pr interval increase vs maximum plasma concentration
Compound 1 – SAD 320mg, 640mg Maximum PR Interval Increase vs Maximum Plasma Concentration

Pre-dose

Baseline variability

3 measurements/patient

(0.93 µM)

(1.9 µM)

(3.7 µM)

(5.6 µM)

(4.7 µM)

G Erdemli, Ion Channel Retreat, Vancouver, June 28-30 2010

cardiac ion channel profiling on automated systems a part of preclinical integrated risk assessment
Cardiac Ion Channel Profiling on Automated SystemsA part of preclinical integrated risk assessment

Structure

G Erdemli, Ion Channel Retreat, Vancouver, June 28-30 2010

indirect modulation of herg channels
Indirect modulation of hERG channels
  • An indirect QTc mechanism is invoked if a drug produces:
    • An in vivo QTc prolongation despite no in vitro signal indicating direct effect on cardiac ion channels.
    • A clinical QTc prolongation despite no preclinical signal indicating direct effect on cardiac ion channels
  • Potential mechanisms
    • Channel trafficking, maturation and degradation
    • Hypokalemia - regulation of ventricular repolarization by plasma potassium levels
      • Furosemide has no effect on hERG current and APD in rabbit purkinje fiber but causes QT interval prolongation
      • Inverse relationship between the plasma potassium levels and QT and QTc interval durations
    • Changes in plasma glucose levels
      • Hypoglycemia-induced hERG channel inhibition - due to decrease in intracellular ATP
      • Hyperglycemia-induced hERG channel inhibition - due to production of reactive oxygen species
    • Changes in autonomic tonus
      • Adrenergic modulation of hERG channel - Functional coupling of α and β adrenoceptors to hERG channel
      • Adrenergic regulation of IKs channel - functional coupling of β adrenoceptors to IKs
    • Macromolecular Complexes can produce ↑QTc – Ankyrins, Caveolin-3, Syntrophin - No direct drug-induced examples, but candidates for off-target interactions

G Erdemli, Ion Channel Retreat, Vancouver, June 28-30 2010

indirect modulation of cardiac channels definition decision tree
Indirect modulation of cardiac channels Definition & decision tree

Negative in Nav1.5, Cav1.2, hERG, KCNQ1 but QTc prolongation in vivo

PK/PD relationship

Test metabolites

Cmax/AUC driven

Test on other cardiac ion channels

PK/PD disconnect

No effect

  • Delayed disposition (parent/metabolite) to heart tissue
  • Accumulation (parent/metabolite) in heart tissue
  • Modulation of ion channel trafficking/maturation/degradation
  • Modulation of ion channel gene expression
  • Hypokalemia
  • Autonomic nervous system
  • Glucose homeostasis
  • Structural macromolecular complexes

G Erdemli, Ion Channel Retreat, Vancouver, June 28-30 2010

summary20
Summary
  • Automated electrophysiology has been implemented in routine cardiac ion channel safety screen in all stages of drug discovery
  • Allow thousands of compounds profiling with IC50 values and quick turnaround time
  • Assay validation, optimization and setting QC parameters for automated data analysis are key for successful implementation
  • Results show very good correlation with conventional electrophysiology in most cases
  • Common reasons for discrepancies between conventional and automated electrophysiology are differences in
    • compound application duration
    • recording temperature
  • Physicochemical properties of compounds should be taken into consideration for data analysis – solubility, permeability etc

Overall in vitro preclinical cardiac ion channel profiling data provide high quality translational information for integrated risk assessment

G Erdemli, Ion Channel Retreat, Vancouver, June 28-30 2010

acknowledgments
Acknowledgments
  • Chris Penland
  • Dan Meyers
  • TychoHeimbach
  • Albert Kim
  • Dmitri Mikhailov
  • Clayton Springer
  • Bob Pearlstein

Novartis

  • Xueying Cao
  • Tony Lee
  • Mats Holmqvist
  • A Golden
  • Steven Whitebread
  • Karl Chin
  • Mark Deurinck
  • Berengere Dumotier
  • M Traebert
  • Laszlo Urban
  • Fluxion
  • Qin Chen
  • Nianzhen Li
  • Tanner Nevill
  • Juliette Johnson
  • CristianIonescu-Zanetti
  • Jeff Jensen
  • Sophion
  • Ali Yehia
  • Millipore
  • Duncan Jarman

G Erdemli, Ion Channel Retreat, Vancouver, June 28-30 2010