1. Sponsors: Arun Sridhar, Peter J. Clements, Brian Berridge,
InPulse: Development of an iPSC cardiomyocyte (iPSC-CM) platform to assess drug-induced contractility liabilities.
Sponsors:
Arun Sridhar, Peter J. Clements, Brian Berridge,

2. Drug induced contractility change – a balancing act!
Reduced perfusion to end-organs
Places long term stress on the heart
Contractility
Contractility assessment in drug discovery and development for:
Primary & Secondary pharmacology screening paradigms
Hazard management: e.g. inclusion of relevant patient population or additional monitoring in clinical trials
Regulatory implications: Black-box warnings
Slower, costly development with implications on patient health

3. State of contractility assays in discovery and safety
Preclinical safety:
Early indicators of off-target activity at GPCR’s and calcium channels affecting contractility
Isolated adult myocyte measurements
Tissue preparations
Single dose in vivo CV study (first to assess ECG and blood pressure)
Follow up repeat dose CV parameters – limited measures of contractility
Cardiac output and mechanistic studies are undertaken only if signals are found in one or more assays.
Discovery:
Ligand binding
Mechanism based molecular reporters.
Isolated myocyte contractility
In vitro langendorff
In vivo cardiac output and hemodynamic assessments.
Echocardiography
(Current measurements in routine screening is indirect or resource-, time- consuming with heavy reliance on animals)
(Must cater to all drug classes irrespective of therapeutic area!).
(Restricted to cardiovascular drug discovery, rarely beyond!).

4. Evidence of drugs from various therapeutic classes altering cardiac contractile function
Potential role of off-target effects in mediating cardiotoxicity of multi-targeted tyrosine kinase
inhibithors
Nature Reviews Cancer 7, (May 2007)

5. Safety Related Attrition

7. Why are contractility changes important in drug safety screening?
Nature Reviews Drug Discovery 11, (October 2012)

8. Why are the current stem cell screens inadequate?
Heavily focussed on electrophysiology!
Immature, neonatal phenotype with poorly developed architecture and physiology .
Impedence changes ≠ electrophysiology and contractility changes
Currently, electrophysiology, calcium and contractility are all done in separate assays – not a good use of animals and time!
Current methods (using rigid substrates – PDMS based polymers) deliver isometric contraction. A cardiac myocyte contraction is both isometric and isotonic
Cells mature and demonstrate striations, but are not bulked up in volume to aid 2-D cell shortening measurements.

9. The Challenge Vision (What we seek to achieve): How:
Create an assay for stem cell based contractility assay with mature adult-like population grown on an engineered substrate that demonstrates relevant physiology & pharmacology to enable discovery and safety screening of drug induced changes in contractility.
How:
Marry advances in material science/bio-engineering with physiology to deliver a pliable substrate to drive cardiomyocyte maturation.
Re-capitulate ventricular stress-strain relationships on extracellular substrate’s tensile strength (changes in polymerization of the substrate).
Actively contracting iPSC-CMs attached to this substrate will mature based on the load it perceives and develop striations and increased cell volume.
Alterations of load (e.g: by changes in polymerization) will provide normal vs. disease (e.g: hypertrophy) phenotypes to aid comparison.
Validate with demonstrable physiology (as outlined) and pharmacology
Enable a medium throughput screen (as non-invasive as possible) for simultaneous contractility and electrophysiological changes.

10. Framework for comparison

11. Back up slides

12. Caveat to be remembered
The translatable endpoint that is available between pre-clinical and clinical studies for assessment of contractility liabilities is reduction in fractional shorterning or ejection fraction, as assessed by echocardiography.
Advantages:
Non-invasive
Cheaper and easily tolerated in clinical trials in an outpatient and inpatient setting.
Can be pursued in repeat dose setting
Every other measurement from pre-clinical studies are mere indicators to potential changes in ejection fraction in vivo (acutely)
Primary Purpose: Hazard Detection in early pre-candidate screening
Potential 3R’s benefit: The proposed challenge will be a first step to make a potential paradigm change for preclinical assessment of contractility early in discovery and safety screening.

13. iPSC-CM phenotype
Biomaterials Mar;34(10):

14. Why Impedence changes are indirect and rarely accurate?
Action Potential
Ca2+ transient
Impedance readout from Xcelligence Cardio system
An impedance based system will not distinguish an electrical phenomenon (AP prolongation vs. EADs) and Ca2+ transient abnormalities
Pharmacology & Therapeutics Volume 119, Issue