Title: cardiac arrhythmia
1Stroke
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
2Circle of Willis
Rat Ventral Surface MCA Middle Cerebral
Artery ACA Anterior Cerebral Artery
3Rat Models of Focal Cerebral Ischaemia
Permanent MCA Occlusion
Transient MCA Occlusion
Electrocoagulation section of MCA
2 hours ischaemia 22 hrs reperfusion
4GLUTAMATE
Na
Ca
2
NMDA
AMPA
Na
/Ca
Na
Depolarisation
Lipid
Peroxidation
Ca
2
Calpains
NO synthesis
ROS
CELL DEATH
5Glutamate 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)
6Elevated Extracellular Glutamate Is Neurotoxic
7Ischaemic Damage to Neuronal PerikaryaMiddle
Cerebral Artery Occlusion
- Cresyl Violet
- Triangulation
- Hyperchromasia
- Shrinkage
- Microvaculation
8Neuronal Perikaryal Damage in Focal Ischaemia
MCA occlusion in cat multiple coronal planes
9GLUTAMATE
Na
Ca
2
NMDA
AMPA
Na
/Ca
Na
Depolarisation
Lipid
Peroxidation
Ca
2
Calpains
NO synthesis
ROS
CELL DEATH
10NMDA 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
11NMDA Receptor Blockade Reduces Neuronal Damage
Vehicle MK-801
Median 3280mm3
Median 1420mm3
12MCA Occlusion in the CatCerebral Blood Flow
Penumbra and Core
- CBF ( of the contralateral caudate nucleus)
13CBF 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)
14NMDA 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
15Ischaemic Damage to Neuronal Perikarya After MCA
occlusion in the Rat
16NMDA 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
17The Concept of the Ischaemic PenumbraRat MCA
Occlusion (1hour)
18Anatomical Distribution of Ischaemic
Lesion Median Animals
Vehicle
MK-801 Pretreatment
MK-801 Posttreatment
Vehicle
19Circle of Willis
Rat Ventral Surface MCA Middle Cerebral
Artery ACA Anterior Cerebral Artery
20The penumbra is the tissue at risk of infarction
Coyle 1989
GraphicJulien Chuquet
21NMDA 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
22Glutamate 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
23Glycine 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
24Glycine 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
25Why 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
26Neuronal CommunicationThe synapse
27 Axons and Oligodendrocytes Do Not Contain
NMDA Receptors
28Tau Positive Oligodendrocytes Focal Ischaemia
29NMDA Receptor Blockade Fails to Modify
Oligodendrocyte Pathology Free Radical Scavenger
Reduces Oligodendrocyte Pathology
30Grey and White Matter are Damaged by Focal
Cerebral Ischaemia
Neuronal damage
Axonal damage
31MK-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
32White 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
33Tissue 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)
34White Matter contains AMPA receptors
35AMPA 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)
36AMPA 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
37Major 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
38Only 3 treated within 3 hours of stroke onset
39Major Clinical Trials in Stroke
2005Neuroprotection
- Phase III
- NXY-059 Free Rad Scavenger AstraZeneca
-
40Cerovive(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
41NXY-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
42NXY-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)
43NXY-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
44AstraZeneca 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.
45NXY-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
46AstraZeneca 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
47Cerebral Ischaemia-Research at a Crossroad
48Glycine 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)
49Why 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
50Why 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
51NMDA 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)
52D-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)
53Why 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
55NXY-059 in Human Stroke Clinical Trial Design
Saint1
56Animal 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