Increased risk of Torsades de Pointes in streptozotocin-induced - - PowerPoint PPT Presentation

Increased risk of Torsades de Pointes in streptozotocin-induced diabetic rats.

Annie Bouchard Marie-Claude Benoit Sabrina Baillargeon Lawrence Helson George Shopp Dany Salvail

Long QT in diabetic patients

Why are diabetic patients at greater risk of sudden cardiac death?

• QTc prolongation is present in 9-16% of type-1 diabetic patients.
• Diabetic autonomic neuropathy is frequent;
• Humans with autonomic system disorders/impairments are more susceptible to drug-induced

QTc prolongation

Type-1 Diabetes CV autonomic neuropathy Prolonged QTc Bradycardia Torsades de Pointes Sudden cardiac death Low Insulin Low KChIP2 (ITo) and hERG (IKr) expression High Persistent INa (INaP) density

The project

• Rationale

With a reduced repolarisation reserve, human diabetic patients may not be adequately represented in our current cardiac safety models.

• Purpose

1. To characterize the extent, timing, and potential causes of QTc prolongation in a type-1 diabetic rat model 2. To confirm that this type-1 diabetic model exhibited enhanced sensitivity to drug-induced QTc prolongation 3. To test a novel compound with a potential novel mechanism of drug-induced LQTc mitigation

Induction of type-1 diabetes

• Adult male Sprague-Dawley rats
• One 45 mg/kg iv injection of streptozotocin on Day 1
• Day 3: Implantation of subcutaneous osmotic pumps filled with slow insulin

formulated in proprietary stabilization buffer: 2 units per day delivered for 30 days

• The animals were fed normal rat chow ad libitum
• Daily glycaemia tests, clinical signs assessment; weekly insulin tests and ECG

recordings under isoflurane anesthesia prior and after induction

• Drug-induced QTc challenges on Day 30:

– 3 mg/kg crizotinib (lung carcinoma) – 4 mg/kg nilotinib (myelogenous leukemia) – i.v. injections followed by 30+ minutes of recording

Progression of the disease: Insulin and glycaemia

Glucose: OneTouch Verio IQ Insulin: Abcam ELISA 0.0 10.0 20.0 30.0 40.0 50.0 60.0 Baseline Pump + 24h Week 1 Week 2 Week 3 Week 4 Blood glucose (mmol/L)

Progression of glucose and insulin levels after induction

* * * * * * * * * * * * * * * * * * Blood insulin (µU/mL) *

Progression of the disease: QT prolongation

10 20 30 40 50 60 150 155 160 165 170 175 180 185 190 195 Baseline Week 1 Week 2 Week 3 Week 4 Insulin (µU/L) QTc (ms)

Progression of QTc and insulin levels after induction

* * * * * * * * As expected, the kinetics of hypoinsulinemia appear faster than those of QTc

• prolongation. Yet QTc is statistically increased after only 1 week, levels off after 3

weeks post-induction

Decreased repolarisation reserve

100 120 140 160 180 200 220 240 Pre-challenge Nilotinib, 4 mg/kg Crizotinib, 3mg/kg QTc (ms) QTc prolongation in normal and diabetic animals * * * ** ** Nilotinib: Tyrosine kinase inhibitor for the treatment of chronic myelogenous leukemia Crizotinib: anaplastic lymphoma kinase inhibitor, for the treatment of non-small cell lung cancer. For both these compounds, QTc prolongation is one of the dose-limiting toxicities.

Mitigation of QT prolongation: EU-8120

• EU-8120: A proprietary eutectic

blend of phospholipids and fatty acids

• By itself, does not revert the

diabetic-induced LQTc

• Shown to have IKr/hERG current
• salvaging properties
• Currently in clinical

development: it mitigates dose- limiting cardiovascular toxicity and opens the therapeutic window for black-labelled drugs 100 120 140 160 180 200 220 240 Control Nilotinib EU-8120 EU-8120 + Nilotinib QTc (ms) Nilotinib-induced QTc prolongation in type- 1 diabetic rats

*

Prevention of hERG current inhibition

0.00 0.50 1.00 Normalized Current Density hERG current inhibition by Nilotinib and Crizotinib * * Baseline Crizotinib +EU-8120 EU-8120 Nilotinib + EU-8120 Nilotinib Crizotinib

• Manual patch-clamp, physiological temperature, using HEK293 hERG-expressing cells.
• Nilotinib and Crizotinib both inhibit hERG, and received a QTc warning label.
• EU-8120 removes the hERG inhibition completely when administered at a ratio of 9:1

Conclusion Wrap-up

• Streptozotocin-induced type-1 rats exhibit QTc prolongation (Shimoni 1994, Ren

1997, etc.)

• Insulin depletion plays a role in the prolongation of QTc in the type-1 diabetic rats

(Harris, 1996)

• The extent of QTc prolongation can be dialed in with insulin pumps
• Type-1 diabetic rats are more sensitive to QT-prolonging drugs (reduced

repolarisation reserve)

• Maintaining a functional hERG signal contributes to preventing QTc prolongation in

type-1 diabetic rats (EU-8120)

• Not shown: In contrast, maintaining hERG function is NOT sufficient to prevent

drug-induced LQT in type-2 rats: EU-8120 prevents hERG inhibition by nilotinib, but not nilotinib-induced LQT. The core difference between the two types of diabetic rats is the circulating insulin level.

Special thanks

• Lawrence Helson (SignPath Pharma)
• George Shopp (Shopp Consulting)
• Walt Shaw (Avanti Polar Lipids)
• Marie-Claude Benoît IPST
• Sabrina Baillargeon IPST
• Rosie Kryczka IPST
• Annie Bouchard IPST

More information on Poster 039