cardiac arrhythmia

1
Stroke
3rd leading cause of death 60,000 deaths per
annum 300,000 disabled 5 NHS costs 7 social
services costs 20NHS acute beds 25 long stay
beds
single vessel occlusion
Multiple causes Low blood flow damages CNS
cardiac arrhythmia
haemorrhage
2
Circle of Willis
Rat Ventral Surface MCA Middle Cerebral
Artery ACA Anterior Cerebral Artery
3
Rat Models of Focal Cerebral Ischaemia
Permanent MCA Occlusion
Transient MCA Occlusion
Electrocoagulation section of MCA
2 hours ischaemia 22 hrs reperfusion
4
GLUTAMATE
Na
Ca
2

NMDA
AMPA
Na
/Ca
Na

Depolarisation
Lipid
Peroxidation
Ca
2
Calpains
NO synthesis
ROS
CELL DEATH
5
Glutamate is Increased after Ischaemia and
Haemorrhage
FOCAL CEREBRAL ISCHAEMIA
SUBDURAL HAEMATOMA
50
50
MCA
Subdural Blood
Sham
Sham
40
40
30
30
Glutamate (pmol/min)
SDH
MCAO
20
20
10
10
0
0
0
40
80
120
160
0
40
80
120
160
Time(mins)
Time(mins)
6
Elevated Extracellular Glutamate Is Neurotoxic
7
Ischaemic Damage to Neuronal PerikaryaMiddle
Cerebral Artery Occlusion

• Cresyl Violet
• Triangulation
• Hyperchromasia
• Shrinkage
• Microvaculation

8
Neuronal Perikaryal Damage in Focal Ischaemia
MCA occlusion in cat multiple coronal planes
9
GLUTAMATE
Na
Ca
2

NMDA
AMPA
Na
/Ca
Na

Depolarisation
Lipid
Peroxidation
Ca
2
Calpains
NO synthesis
ROS
CELL DEATH
10
NMDA Receptor Blockade Reduces Neuronal Damage
MCA Occlusion in Cats
4000
Vehicle
MK-801
3000

p lt 0.01
Volume(mm3)
2000

1000
0
Cerebral Hemisphere
Cerebral Cortex
Caudate Nucleus
11
NMDA Receptor Blockade Reduces Neuronal Damage
Vehicle MK-801
Median 3280mm3
Median 1420mm3
12
MCA Occlusion in the CatCerebral Blood Flow
Penumbra and Core

• CBF ( of the contralateral caudate nucleus)

13
CBF Threshold for Neuronal Damage Duration and
Severity
30
20
Reversible Deficit
CBF (ml/100g/min)
Infarction
10
0
Permanent
0
1
2
3
Duration (hours)
14
NMDA Receptor Blockade Reduces Neuronal Damage
Treatment initiated at 120mins Post MCAO (cat)
3000
Vehicle
MK-801
2000
p lt 0.05
Volume(mm3)


1000
0
Cerebral Hemisphere
Cerebral Cortex
Caudate Nucleus
15
Ischaemic Damage to Neuronal Perikarya After MCA
occlusion in the Rat
16
NMDA Receptor Blockade Reduces Neuronal Damage
MCA occlusion in rat
150
Vehicle
MK-801(pre)
MK-801(post)

100

p lt 0.01 P lt 0.05

Volume(mm3)

50

0
Cerebral Hemisphere
Cerebral Cortex
Caudate Nucleus
17
The Concept of the Ischaemic PenumbraRat MCA
Occlusion (1hour)
18
Anatomical Distribution of Ischaemic
Lesion Median Animals
Vehicle
MK-801 Pretreatment
MK-801 Posttreatment
Vehicle
19
Circle of Willis
Rat Ventral Surface MCA Middle Cerebral
Artery ACA Anterior Cerebral Artery
20
The penumbra is the tissue at risk of infarction
Coyle 1989
GraphicJulien Chuquet
21
NMDA ReceptorMultiple Sites of Drug Action
Glutamate Antagonist Eg D-CPPene
Glycine Antagonist Eg GV150562 Ion Channel
Block Eg MK-801 Voltage Dependent Block
Eg Magnesium Polyamine Site Block Eg
Eliprodil
MK-801
22
Glutamate Receptor Antagonists Clinical
Development Status 1999
NMDA Receptor

• Ion Channel MK-801 Remacemide
• CNS 1102 AR 15896
• CNS 5161 Memantine
• Dextrorphan NPS1506
• Competitive D-CPPene CGS 19755
• Glycine GV 150526 ACEA 1021
• Subtype (2B) CP 101606 Eliprodil
• NBQX GYKI 52466
• YM 90K YM 872
• LY 293558 SPD 502

AMPA Receptor
23
Glycine Antagonist in Neuroprotection (GAIN)
Eligible patients 1808
Screened not randomised 4
Randomised 1804
Randomised but not treated
Intent-to-treat population 1788 (All patients
receiving at least one dose of study medication
as randomised)
Received GV150526 (ITT) 891 within 6hrs of onset
Received Placebo (ITT) 897 within 6hrs of onset
Ischaemic stroke (Primary efficacy)
721 Haemorrhage stroke (ICH) 170
Ischaemic stroke (Primary efficacy)
734 Haemorrhage stroke (ICH) 163
24
Glycine Antagonist in Neuroprotection (GAIN)
Primary Outcome
Barthel Index
95-100
60-90
0-55
Dead
GV150526 (n 721)
246 (34)
136 (19)
192 (27)
147 (20)
Placebo (n 734)
256 (35)
133 (18)
207 (28)
138 (19)
CSF level is 0.04
of plasma concentration
25
Why has neuroprotection failed for stroke?

• Adequacy of Dose
• Plasma Brain
• Uncontrolled Physiology
• Blood pressure Temperature Glucose
• Penumbra in Man
• Volume Temporal Evolution
• Therapeutic Window in Man
• Protect All Brain Cells
• Axons Oligodendrocytes

26
Neuronal CommunicationThe synapse
27
Axons and Oligodendrocytes Do Not Contain
NMDA Receptors
28
Tau Positive Oligodendrocytes Focal Ischaemia
29
NMDA Receptor Blockade Fails to Modify
Oligodendrocyte Pathology Free Radical Scavenger
Reduces Oligodendrocyte Pathology
30
Grey and White Matter are Damaged by Focal
Cerebral Ischaemia
Neuronal damage
Axonal damage
31
MK-801 does not reduce white matter damage
Cortical Neuronal Necrosis
Axonal Injury
125
125
100
100
75
75
APP Score
Neuronal Necrosis (mm2)
50
50
25
25
0
0
-30
-20
-10
0
10
-30
-20
-10
0
10
Stereotactic Co-ordinate (mm)
Stereotactic Co-ordinate (mm)
Vehicle
MK-801
MCA Occlusion in Cat 6h
Yam et al 2000
32
White matter and grey matter damage Are reduced
by early reperfusion
Oligos
Neurons
Axons
250
350
300
APP score
125
150
Volume (mm3)
Volume (mm3)

175


0
0
0
PERM
TRANS
PERM
TRANS
PERM
TRANS
Valeriani et al 2000
33
Tissue Plasminogen Activator in Acute Stroke
Barthel index
95-100
55-90
0-50
Dead
t - PA n 168
50
16
17
17
Placebo n 165
38
23
18
21
P 0.008
NEJM (1995)
34
White Matter contains AMPA receptors
35
AMPA Receptor Activation Damages Neuronal
Perikarya,Axons and Oligodendrocytes
Oligodendrocytes
Axons
Perikarya
)
2
12.5

40
200


10.0

30
3)
7.5
Volume of Tau positive cells (mm
20
100
MAP-5 score
5.0
Lesion Volume (mm

10

2.5
0
0
0
Vehicle
AMPA
AMPA
Veh
Veh
AMPA
AMPA
AMPA
AMPA

2.5 nmol
25 nmol
25 nmol
2.5 nmol
(2.5nmol)
(25nmol)
36
AMPA Blockade Protects Axons, Oligodendrocytes an
d Neuronal Perikarya from Ischaemic Damage
Axons
Oligodendrocytes
Neuronal Perikarya
30
200
75

20
50
Volume(mm3)
Volume(mm3)
APP Score
100


10
25
0
0
0
SPD 502
Vehicle
SPD 502
Vehicle
Vehicle
SPD 502
37
Major Clinical Trials in Stroke
2003Neuroprotection

• Phase III
• NXY-059 Free Rad Scavenger AstraZeneca
  
• Bay 3702 5HT1a agonist Bayer
• Magnesium Multiple actions MRC
• Phase II
• FK 506 Calcineurin Inhibitor Fujisawa
  
• YM 872 AMPA antagonist Yamanouchi
  

38
Only 3 treated within 3 hours of stroke onset
39
Major Clinical Trials in Stroke
2005Neuroprotection

• Phase III
• NXY-059 Free Rad Scavenger AstraZeneca
  

40
Cerovive(NXY-059) Free Radical ScavengerLong
Therapeutic Window in Focal IschaemiaTreatment
Initiated 3 Hours After Onset of Ischaemia
Rat Transient MCAO 2 Hours Occlusion
Kuroda et al 1999
41
NXY-059 Clinical Trials in Stroke

• SAINT 1 (Phase 3)
• 1500 patients with acute stroke
• AstraZeneca Press Release May 2005
• Lees et al New England J Medicine Feb 2006
• Significant improvement (p0.038) in disability
• No significant change in NIHSS (neurological
  score)
• SAINT 2 (Phase 3)
• Increase sample size to 3200 patients
• AstraZeneca Press Release 26th October 2006

42
NXY-059 and Human Stroke Clinical Trial SAINT 1
Modified Rankin Scale
4
0
1
2
3
5 (or dead)
93 (11)
175 (21)
170 (20)
204 (24)
99 (12)
108 (13)
Placebo (n 849)
131 (15)
205 (24)
121 (14)
144 (17)
97 (11)
153 (18)
NXY059 (n 850)
Significant Benefit P 0.038
Lees et al NEJM
(2006)
43
NXY-059 Clinical Trials in Stroke

• SAINT 1 (Phase 3)
• 1500 patients with acute stroke
• AstraZeneca Press Release May 2005
• Lees et al New England J Medicine Feb 2006
• Significant improvement (p0.038) in disability
• No significant change in NIHSS (neurological
  score)
• SAINT 2 (Phase 3)
• Increase sample size to 3200 patients
• AstraZeneca Press Release 26th October 2006

44
AstraZeneca Press Release26th October 2006
AstraZeneca Announces SAINT II Trial Results
Showed No Efficacy in Acute Ischaemic
StrokeResults from the SAINT II (Stroke Acute
Ischaemic NXY-059 Treatment) trial, announced
today by AstraZeneca, showed that the
investigational drug NXY-059 did not meet its
primary outcome of a statistically significant
reduction in stroke-related disability, as
assessed by the modified Rankin Scale (mRS)
(p0.33, odds ratio 0.94) compared to placebo.
Subgroup analyses, including time to treatment,
did not demonstrate a treatment benefit.
45
NXY-059 and Human StrokePhase 3 Clinical Trial-
SAINT 2
Modified Rankin Scale
n1631
n1610
No Significant Benefit P0.33 Shuaib,Lees et al
NEJM August 2007
46
AstraZeneca Share Price 2006-7
25th Oct 2006
5 billion fall
26th Oct 2006
On 26th Oct 2006,the market capitalisation of
Astra Zeneca fell by more than 5billion
47
Cerebral Ischaemia-Research at a Crossroad
48
Glycine Antagonist in Neuroprotection (GAIN)
Primary Outcome
Barthel Index
95-100
60-90
0-55
Dead
GV1500526 (n721)
246 (34)
136 (19)
192 (27)
147 (20)
Placebo (n734)
256 (35)
133 (18)
207 (28)
138 (19)
49
Why has neuroprotection failed for stroke?

• Adequacy of Dose
• Plasma Brain
• Uncontrolled Physiology
• Blood pressure Temperature Glucose
• Penumbra in Man
• Volume Temporal Evolution
• Therapeutic Window in Man
• Protect All Brain Cells
• Axons Oligodendrocytes

50
Why has neuroprotection failed for stroke?

• Adequacy of Dose
• Dose limiting cardiovascular and CNS effects
• NMDA antagonists
• AMPA antagonists
• Ion channel blockers
• Low brain entry
• BFGF 155 amino acid growth factor
• SNX III 25 amino acid conotoxin
• Competitive glutamate antagonists
• GV 150526 CSF 0.04 of plasma
• D-CPPene CSF 10 of plasma

51
NMDA Receptor Blockade Reduces Neuronal
Damage D-CPPene Cat MCA Occlusion
40
Pretreatment (15mins) Posttreatment (60mins)
p lt 0.01
30
Volume of Ischaemic Damage ()
20


10
0
0
1.5
4.5
15
D-CPPene (mg/kg)
52
D-CPPene in Human Head Injury
o 950 Patients GCS 4-8 o Treatment within 12
hours of injury o 200mg every 12 hours for 50
days o No overall benefit o Increased time in
ICU (3 days more) o Increased respiratory
infections (47 versus 39) o Early
treatment (4 hours) benefits (but n is
small)
53
Why has neuroprotection failed for stroke?

• Adequacy of Dose
• Plasma Brain
• Uncontrolled Physiology
• Blood pressure Temperature Glucose
• Penumbra in Man
• Volume Temporal Evolution
• Therapeutic Window in Man
• Protect All Brain Cells
• Axons Oligodendrocytes

54
Human Stroke MCA Occlusion
3Hours 1Day 11 Days

• CT scan Structural Damage
• SPECT Cerebral Blood Flow
  
  
  

55
NXY-059 in Human Stroke Clinical Trial Design
Saint1
56
Animal Models of Cerebral Ischaemia

• To replicate human diseases eg stroke? NO!
• Complex and diverse
• Other concomitant pathology(Hypertension,ag
  e,diabetes)
• Ultimately futile
• To investigate mechanisms, pertinent to disease
  YES!
• Extract mechanism from complexity
• Study mechanism in a highly controlled
  manner
• Extrapolate to human disease with caution

Cerebral Ischaemia low blood flow to brain