This document discusses the use of cell-based ion channel and cardiac safety assays in drug development. It notes that ion channels are responsible for electrical activity in the heart and that drugs blocking the hERG channel can cause dangerous arrhythmias by prolonging the QT interval. The document outlines how screening for effects on hERG and other cardiac ion channels in vitro and in silico, along with evaluating QT prolongation in vivo, allows assessment of torsadogenic risk to help identify potentially dangerous drugs. It also discusses using cardiomyocytes to confirm electrophysiology data and evaluate multi-channel effects to comprehensively assess proarrhythmic risk.

1. CELL-BASED ION
CHANNEL AND CARDIAC
SAFETY ASSAYS
Drug Development “Boot Camp”: Practical Aspects of
Positioning Your Research
EVERY STEP OF THE WAY
EVERY STEP OF THE WAY

2. THE ECG IS THE ELECTRICAL ACTIVITY MEASURED FROM AN
ENTIRE HEART
2 EVERY STEP OF THE WAY

3. THE ACTION POTENTIAL IS THE ELECTRICAL ACTIVITY
MEASURED FROM AN INDIVIDUAL CARDIOMYOCYTE
3 EVERY STEP OF THE WAY

4. ION CHANNELS ARE RESPONSIBLE FOR THE ELECTRICAL
ACTIVITY OF THE HEART
4 EVERY STEP OF THE WAY
Ca2+
hERG
KvLQT1/minK
Kv4.3
Nav1.5
Cav1.2
Kir1.2

5. ION CHANNELS ARE RESPONSIBLE FOR THE ELECTRICAL
ACTIVITY OF THE HEART
5 EVERY STEP OF THE WAY
hERG

6. DRUG-INDUCED TORSADE DE POINTES (TDP)
6 EVERY STEP OF THE WAY
Normal sinus rhythm
Torsade de Pointes
Ferimini and Fossa, Nature Reviews: Drug Discovery,
Volume 2, 2003

7. TDP INCIDENCE TOO LOW TO DETECT IN CLINICAL TRIALS
TERFENADINE: TDP IN 1/25,000 PRESCRIPTIONS
7 EVERY STEP OF THE WAY
Normal sinus rhythm
Torsade de Pointes
Ferimini and Fossa, Nature Reviews: Drug Discovery,
Volume 2, 2003

8. 8 EVERY STEP OF THE WAY
hERG
Prolonged QT Interval
DRUGS THAT BLOCK HERG AND PROLONGS THE QT
INTERVAL MAY CAUSE TDP

9. GUIDANCE FOR INDUSTRY ICHS7B NONCLINICAL EVALUATION OF THE
POTENTIAL FOR DELAYED VENTRICULAR REPOLARIZATION (QT INTERVAL
PROLONGATION)
9 EVERY STEP OF THE WAY
Evaluation of torsadogenic risk determined by
effects on only 2 surrogates of TdP:
1. In Vivo QT Interval Prolongation
2. hERG Inhibition

10. THIS STRATEGY HAS PROVEN TO BE SUCCESSFUL .
10 EVERY STEP OF THE WAY
Drug Class hERG
Blocker, QT
Prolonger
Date
Withdrawn
Terfenadine Antihistamine √ 1998
Sertindole Antipsychotic √ 1998
Astemizole Antihistamine √ 1999
Grepafloxacin Antibiotic √ 1999
Cisapride Prokinetic √ 2000
Droperidol Antipsychotic √ 2001
Levomethadyl Opiate Dependence √ 2003

11. THIS NEW STRATEGY HAS PROVEN TO BE SUCCESSFUL
11
0.01 0.1 1 10 100 1000 10000
Concentration (µM)
Verapamil
hERG IC50
Cav1.2 IC50
Nav1.5 IC50
KvLQT1/minK IC50
Kir2.1 Est. IC50
Plasma Level
Ca2+
• Blocks hERG
• Not Very Potent Inhibitor of KvLQT1/mink or Kir2.1

12. THIS NEW STRATEGY HAS PROVEN TO BE SUCCESSFUL
12
Ca2+
Na+
0.01 0.1 1 10 100 1000 10000
Concentration (µM)
Verapamil
hERG IC50
Cav1.2 IC50
Nav1.5 IC50
KvLQT1/minK IC50
Kir2.1 Est. IC50
Plasma Level
• Blocks hERG
• Not Very Potent Inhibitor of KvLQT1/mink or Kir2.1
• Blocks Cav1.2

13. LOGISTIC REGRESSION MODELS
13 EVERY STEP OF THE WAY
Kramer et al., Sci Rep. 2013;3:2100.

14. THIS NEW STRATEGY HAS PROVEN TO BE SUCCESSFUL
14
Action
Potentials
Field
Potentials
Stem Cell Derived
Cardiomyocytes
↓ Action Potential
Duration
↓ Field Potential
Duration

15. THIS NEW STRATEGY HAS PROVEN TO BE SUCCESSFUL
15 EVERY STEP OF THE WAY
• Package Insert = No TdP Risk
• Does Not Prolong The QT Interval
Blocks hERG
and Cav1.2
Ca2+
0.01 0.1 1 10 100 1000 10000
Concentration (µM)
Verapamil
hERG IC50
Cav1.2 IC50
Nav1.5 IC50
KvLQT1/minK IC50
Kir2.1 Est. IC50
Plasma Level
Vicente J, Johannesen L et al. Comprehensive T wave morphology assessment in a randomized clinical study of dofetilide, quinidine, ranolazine, and verapamil. J Am Heart Assoc. 2015 Apr 13;4(4).
Blocks hERG
and Cav1.2

16. COMPREHENSIVE IN VITRO PROARRHYTHMIA ASSAY (CIPA)
16 EVERY STEP OF THE WAY
Confirmation of
Electrophysiology Data
using Cardiomyocytes
Function Effects on
Multiple Cardiac
Currents
In Silico Models
Ca2+
Proarrhythmia
Assessment

17. MECHANISM OF ACTION
17 EVERY STEP OF THE WAY
Cardiovascular

18. MECHANISM OF ACTION
18 EVERY STEP OF THE WAY
Cardiovascular
Nav1.5
X

19. MECHANISM OF ACTION
19 EVERY STEP OF THE WAY
Cardiovascular
Nav1.5
X

20. MECHANISM OF ACTION
20 EVERY STEP OF THE WAY
Cardiovascular
Nav1.5
X
Kir3.1/3.4
X

21. MECHANISM OF ACTION
21 EVERY STEP OF THE WAY
Cardiovascular
Nav1.5
X
Kir3.1/3.4
X

22. MECHANISM OF ACTION
22 EVERY STEP OF THE WAY
Cardiovascular
Nav1.5
X
Kir3.1/3.4
XKir6.2/SUR2A
X

23. CHANNEL PANELS
23 EVERY STEP OF THE WAY
hERG (Kv11.1)
Cav1.2/β2/α2δ1
Cardiovascular
Kir6.2/SUR2A
Nav1.5
Kir3.1/3.4

24. CHANNEL PANELS
24 EVERY STEP OF THE WAY
hERG (Kv11.1)
Kv4.3
KvLQT1/mink (Kv7.1)
Kv1.5
Cav3.2
HCN2 and HCN4
Kir2.1, Kir3.1/3.4
Nav1.5
Kir6.2/SUR2A
Cav1.2/β2/α2δ1
BK, IK and SK3, ENaC
TRPC1, TRPC4, TRPC6,
TRPM4, TRPV1 and TRPV4NCX1, nAChRα7 and P2X4
Cardiovascular

25. CHANNEL PANELS
25 EVERY STEP OF THE WAY
hERG (Kv11.1)
Kv1.3, Kv1.4,
Kv4.2/KChiP2.2, KCNQ2/3, KCNQ2/4
Cav2.1/β4/α2δ1,
Cav2.2/β3/α2δ1 and Cav3.2
NR1/NR2B, HCN1
nAChRα7, GABA (α3β3γ2)
P2X1, P2X2, P2X3, P2X4 and P2X7
Nav1.1, Nav1.2, Nav1.3, Nav1.7 and
Nav1.8/β3
TRPA1, TRPC4, TRPM4, TRPM8, TRPV1 and
TRPV4
NMDA (NR1/NR2A
BK and IK, ASIC1a, ASIC2a and ASIC3
Kv4.3
KvLQT1/mink (Kv7.1)
Kv1.5
Cav3.2
HCN2 and HCN4
Kir2.1, Kir3.1/3.4
Nav1.5
Kir6.2/SUR2A
Cav1.2/β2/α2δ1
BK, IK and SK3, ENaC
TRPC1, TRPC4, TRPC6,
TRPM4, TRPV1 and TRPV4NCX1, nAChRα7 and P2X4
Cardiovascular
Pain/Inflammation

26. CHANNEL PANELS
26 EVERY STEP OF THE WAY
hERG (Kv11.1)
Kv1.3, Kv1.4,
Kv4.2/KChiP2.2, KCNQ2/3, KCNQ2/4
Cav2.1/β4/α2δ1,
Cav2.2/β3/α2δ1 and Cav3.2
NR1/NR2B, HCN1
nAChRα7, GABA (α3β3γ2)
P2X1, P2X2, P2X3, P2X4 and P2X7
Nav1.1, Nav1.2, Nav1.3, Nav1.7 and
Nav1.8/β3
TRPA1, TRPC4, TRPM4, TRPM8, TRPV1 and
TRPV4
NMDA (NR1/NR2A
BK and IK, ASIC1a, ASIC2a and ASIC3
CLC-2,
Cav2.1/β4/α2δ1 and Cav3.2
HCN1 and HCN2
GABAA (α1β2γ2, α2β2γ2, α5β2γ2
NR1/NR2A, NR1/NR2B)
BK, IK, SK2 and SK3
Kv1.1, Kv4.2/KChiP2.2
KCNQ2/3, KCNQ2/4, KCNQ3/5
Nav1.1, Nav1.2, Nav1.3 and Nav1.6
Kv4.3
KvLQT1/mink (Kv7.1)
Kv1.5
Cav3.2
HCN2 and HCN4
Kir2.1, Kir3.1/3.4
Nav1.5
Kir6.2/SUR2A
Cav1.2/β2/α2δ1
BK, IK and SK3, ENaC
TRPC1, TRPC4, TRPC6,
TRPM4, TRPV1 and TRPV4NCX1, nAChRα7 and P2X4
Seizure/Convulsion
Cardiovascular
Pain/Inflammation

27. CHANNEL PANELS
27 EVERY STEP OF THE WAY
hERG (Kv11.1)
Kv1.3, Kv1.4,
Kv4.2/KChiP2.2, KCNQ2/3, KCNQ2/4
Cav2.1/β4/α2δ1,
Cav2.2/β3/α2δ1 and Cav3.2
NR1/NR2B, HCN1
nAChRα7, GABA (α3β3γ2)
P2X1, P2X2, P2X3, P2X4 and P2X7
Nav1.1, Nav1.2, Nav1.3, Nav1.7 and
Nav1.8/β3
TRPA1, TRPC4, TRPM4, TRPM8, TRPV1 and
TRPV4
NMDA (NR1/NR2A
BK and IK, ASIC1a, ASIC2a and ASIC3
CLC-2,
Cav2.1/β4/α2δ1 and Cav3.2
HCN1 and HCN2
GABAA (α1β2γ2, α2β2γ2, α5β2γ2
NR1/NR2A, NR1/NR2B)
BK, IK, SK2 and SK3
Kv1.1, Kv4.2/KChiP2.2
KCNQ2/3, KCNQ2/4, KCNQ3/5
Nav1.1, Nav1.2, Nav1.3 and Nav1.6
Kv4.3
KvLQT1/mink (Kv7.1)
Kv1.5
Cav3.2
HCN2 and HCN4
Kir2.1, Kir3.1/3.4
Nav1.5
Kir6.2/SUR2A
Cav1.2/β2/α2δ1
BK, IK and SK3, ENaC
TRPC1, TRPC4, TRPC6,
TRPM4, TRPV1 and TRPV4NCX1, nAChRα7 and P2X4
Seizure/Convulsion
Cardiovascular
Pain/Inflammation
Psychiatric Disorder Cav1.3/β3/α2δ
(GABA (α1β3γ2, α2β3γ2, α3β3γ2,
α4β3γ2 and α5β3γ2),
nACHR (α4/β2, α7, α3β4α5,
α6/3β2β3)
NMDA (NR1/NR2A,
NR1/NR2B, NR1/NR2C
and NR1/NR2D))
KCNQ2/3 and KCNQ3/5
SK1, SK2 and SK3

28. ACKNOWLEDGEMENTS
28 EVERY STEP OF THE WAY
Jessica Brimecombe, PhD
Luke Armstrong, PhD
Carlos Obejero-Paz, MD, PhD
Andrew Bruening–Wright, PhD
Yuri-Kuryshev, PhD
Bob Ostroski, BS
Kerri Uffman, BS