Transcript Current Concepts In Therapeutic Angiogenesis

Current Concepts In Therapeutic
Angiogenesis
C. Michael Gibson M.S., M.D.
Scope of Coronary Artery Disease
• ~ 15 - 20 million Americans have a history
of MI, angina, or both
• Cardiovascular disease is the number
one cause of death in the US
• ~ 500,000 deaths per year
• 1,500,000 new or recurrent MI’s per year
AHA Databank
Scope of Coronary Artery Disease
• ~ 10 million Americans have angina
• ~ 350,000 new cases of angina
diagnosed each year
• ~ 1.5 million coronary angiograms
per year
• ~ 500,000 PTCA per year
• ~ 500,000 CABGs per year
AHA Databank
Current Therapeutic Options
Medical
• Antianginals
• Antiplatelet Agents
• Lipid Lowering
Agents
• Anticoagulants
• Vasodilators
Interventional
• PTCA
• CABG
• TMR/PMR
• Cardiac
Transplantation
• PVD: Amputation
New Therapeutic Option
Therapeutic Angiogenesis
Therapeutic Angiogenesis: Definitions
Angiogenesis
• The formation of new capillary blood vessels from
existing microvessels by sprouting, i.e. cellular
outgrowth
Vasculogenesis
• The formation of new blood vessels of all types from
blood islands, i.e. committed stem cells, in early
embryogenesis
Growth Factor
• Polypeptide which acts as a regulator of cellular
function, including proliferation, migration,
differentiation, and survival/apoptosis
Angiogenic Growth Factors
• Basic fibroblast growth
factor (bFGF)
• Acidic fibroblast growth
factor (aFGF)
• Angiogenin
• Angiotropin
• Insulin-like growth factor
• Interleukin-8
• Platelet activating factor
(PAF)
• Platelet-derived growth factor
(PDGF)
• Proliferin
• Transforming growth factor-
• Transforming growth factor-
• Tumor necrosis factor-
• Vascular endothelial growth
factor (VEGF)
J. Battegay: J. Mol Med; 1995
Basic Fibroblast Growth Factor (bFGF)
• 154 amino acids, MW 18 kD
• Additional higher MW forms exist
• Post-translational modification may yield a
shorter form
• Present in almost all cells
• Present from embryogenesis to adult cells
• Released from extracellular sites by heparin
and various proteolytic enzymes
bFGF Receptors
• The cell receptor is a transmembrane
tyrosine kinase
• Found on numerous cell types
• Receptor expression upregulated by
injury (PTCA & ischemia)
• bFGF Binds to heparin which protects it
from degradation
• Seperate binding sites for bFGF receptor
and heparin
Functions of Growth Factors
• Embryogenesis: Stimulates proliferation &
differentiation of a variety of cells
• Wound Healing: Stimulates migration and
proliferation of connective tissue
• Cytoprotection: CNS, vascular smooth
muscle and endothelial cells
• Angiogenesis: Ischemic & Non-Ischemic
• Active at 0.1 to 1.0 ng/ml
Endothelial Cell Migration (m 72 hours)
Bovine Endothelial Cell Migration
Control
1200
+bFGF
1000
800
600
400
200
0
5
15
25
Passage Number
35
45
Augustin-Voss et al.
Impact of bFGF on Bovine Endothelial Cell Proliferation
Proliferation % / 48 hr
1200
1000
800
600
400
200
0
Control
+bFGF
Augustin-Voss et al.
Functions of bFGF
Non-ischemic Angiogenesis
• Promotes endothelial cell migration and
tube formation
• Stimulates the production of collagenases
and plasminogen activator necessary for
basement membrane remodeling
M. Klagsbrun: Progress Growth Factor Research; 1989
Ischemic Angiogenesis
• Endogenous bFGF production
in the presence of ischemia
• Impact of exogenous bFGF on
ischemic tissues
Ischemic Angiogenesis
Longitudinal Changes in Myocardial Basic
Fibroblast Growth Factor (FGF-2) Activity
Following Coronary Artery Ligation in the Dog
Michael V. Cohen et al.
Albert Einstein College of Medicine
M. Cohen: J Mol Cell Cardiol; 1994
Ischemic/Normal Myocardial bFGF ratio
Demonstration of Endogenous Tissue Production of bFGF:
Canine LAD Occlusion Model
3
 Endogenous bFGF
production assayed in
ischemic and adjacent
normal cardiac tissue
 bFGF production
rose as early as 2
hours
*
2.5
2
*
1.5
1
0.5
0
2 Hours
1 Week
2 Weeks
8 Weeks
Time Following Canine LAD Occlusion
Cohen et al: J Mol Cell Cardiol; 1994
Production of Growth Factors in Ischemia:
Other Indirect Evidence
 Fujita et al measured the bFGF levels in the
pericardial fluid of patients undergoing open heart
surgery for unstable angina (CABG) versus those
undergoing surgery for non-ischemic causes
Elevated bFGF levels found in the pericardial fluid
of patients with unstable angina
M. Fujita et al, Circulation; 1996
Ischemic Angiogenesis & Exogenous
Growth Factors : Peripheral Models
Baffour et al.
• Rabbit model of hind limb ischemia (ligated main
arteries in staged procedure over 2 weeks)
• Compared two weeks of IM bFGF to saline
• Results:
• bFGF groups had angiographically improved
collaterals
• bFGF groups had greater capillary density (per mm
and per muscle fiber)
• bFGF groups had greater muscle viability
R. Baffour et al, J Vasc Surg; 1992
Ischemic Angiogenesis & Exogenous
Growth Factors : Peripheral Models
Yang et al
• Rat model of hind limb ischemia
• Compared one to four weeks of continuous intraarterial bFGF (1 g/day) to heparinized saline control
• Demonstrated improvement in:
• Collateral blood flow by microspheres
• Capillary density
• Muscle performance by stimulated tension
H. Yang et al, Circ. Res 1996
Collateral Flow (ml / min / 100g)
Ischemic Angiogenesis & Exogenous
Growth Factors : Peripheral Models
*
60
50
40
*
Control
bFGF
30
20
10
0
Base
1 Week 2 Weeks 4 Weeks
Time Following Hind Limb Arterial Occlusion
H. Yang et al, Circ. Res.; 1996
Ischemic Angiogenesis & Exogenous
Growth Factors : Cardiac Models
Uchida et al
• Occluded canine LAD model
• Compared intrapericardial bFGF, heparin, or both to
saline control (drug given 30 minutes after occlusion)
• Measured:
• Ejection fraction
• Capillary density
• Infarct size
Y. Uchida et al, Am Heart J; 1995
Ischemic Angiogenesis & Exogenous
Growth Factors : Cardiac Models
Saline
Heparin
bFGF
Hep+bFGF
0.7
Ejection Fraction
0.6
0.5
*
*
0.4
0.3
0.2
0.1
0
Base
Y. Uchida: Am Heart J; 1995
30 min.
1 month
Time Following Arterial Occlusion
Infarcted Weight (% of LV)
Ischemic Angiogenesis & Exogenous
Growth Factors : Cardiac Models
30
25
‡
20
15
*
10
5
0
Saline
Heparin
bFGF
Hep +
bFGF
Y. Uchida et al, Am Heart J; 1995
Capillary Number per 200 m
Ischemic Angiogenesis & Exogenous
Growth Factors : Cardiac Models
‡
9
8
7
6
5
4
3
2
1
0
Noninfarct Zone
Saline
Infarct Zone
*
Heparin
bFGF
Hep+bFGF
Y. Uchida et al, Am Heart J; 1995
Ischemic Angiogenesis & Exogenous
Growth Factors : Cardiac Models
Ameroid constriction of porcine circumflex
• Compared intrapericardial bFGF and/or heparin to
saline control
• Measured:
• Angiographic collaterals
• Microsphere blood flow
• MRI Cardiac function
• MRI collateral flow
M. Simmons, personal communication; 1997
Circumflex Flow (ml / min / g)
Ischemic Angiogenesis & Exogenous
Growth Factors : Cardiac Models
1.4
Saline
1.2
bFGF 30
1
Heparin
*
* *
bFGF 200
bFGF 2000
0.8
0.6
0.4
0.2
0
0 Weeks
4 Weeks
Time Post Drug Administration
M. Simmons, personal communication; 1997
Delayed Contrast Arrival Extent (%)
Ischemic Angiogenesis & Exogenous
Growth Factors : Cardiac Models
30
25
20
*
15
*
10
*
5
0
Saline
Heparin
bFGF
30
bFGF
200
bFGF
2000
M. Simmons, personal communication; 1997
Ischemic Angiogenesis & Exogenous
Growth Factors : Cardiac Models
Lazarous et al.
• Ameroid constriction of porcine circumflex
• Daily systemic bFGF (4 to 9 weeks) vs saline
control
• Measured microsphere determinations of
collateral blood flow
D. Lazarous et al, Circulation; 1995
Ischemic Angiogenesis & Exogenous
Growth Factors : Cardiac Models
D. Lazarous et al, Circulation; 1995
Ischemic Angiogenesis & Exogenous
Growth Factors : Cardiac Models
Lazarous et al. Short Infusion Model
• Ameroid constriction of porcine circumflex
• Shorter duration of systemic bFGF (7 days) or
VEGF to saline control
• Measured microsphere determinations of
collateral blood flow
D. Lazarous et al, Circulation; 1996
Lazarous et al: Data Following 7 Day Infusions
D. Lazarous: Circulation; 1996
Ischemic Angiogenesis & Exogenous
Growth Factors : Cardiac Models
Yanagisawa-Miwa et al.
• Acute occlusion of canine LAD
• Compared two bolus circumflex injections of bFGF vs
saline
• Measured:
• LV Function
• Infarct size
• Histologic assessment of collateral growth
A. Yanagisawa-Miwa et al, Science; 1992
Ischemic Angiogenesis & Exogenous
Growth Factors : Cardiac Models
Ejection Fraction
0.7
Saline
bFGF
0.6
*
0.5
0.4
0.3
0.2
0.1
0
Baseline
30 Min.
1 Week
Time post Infarction
A. Yanagisawa-Miwa: Science; 1992
Infarct weight / LV weight (%)
Ischemic Angiogenesis & Exogenous
Growth Factors : Cardiac Models
25
*
20
15
10
5
0
bFGF
Saline
A. Yanagisawa-Miwa et al, Science; 1992
Ischemic Angiogenesis & Exogenous
Growth Factors : Cardiac Models
*
100
Arteriole Number / Unit Area
Capillary Number / Unit Area
90
16
80
70
60
50
40
30
20
12
10
8
6
4
10
2
0
0
Control
bFGF
*
14
Control
bFGF
A. Yanagisawa-Miwa et al, Science; 1992
Ischemic Angiogenesis & Exogenous
Growth Factors : Cardiac Models
Horrigan et al.
• Four hour balloon occlusion of canine LAD
• Compared two bolus LM injections of bFGF or vehicle
• Measured:
• Infarct size
• Histologic assessment of collateral growth
M. Horrigan et al, Circulation; 1996
Infarct Size (% area at risk)
Ischemic Angiogenesis & Exogenous
Growth Factors : Cardiac Models
30
25
20
*
15
10
5
0
Vehicle
bFGF
M. Horrigan et al, Circulation; 1996
Multi-Center, Single-Blind, Dose
Escalation, Safety and Tolerability Study
of Recombinant Fibroblast Growth
Factor-2 (rFGF-2) in Subjects with
Advanced Coronary Artery Disease
Chiron Study
Study Objectives
• Evaluate safety, tolerability and
pharmacokinetics of short-term (20 min)
intracoronary (IC) and intravenous (IV) single
infusions of ascending doses of rFGF-2
• Determine maximum tolerated IC and IV doses
• Measure preliminary efficacy data using
nuclear stress imaging and cardiac MRI
Study Design
• Study Agent
• Recombinant protein produced in yeast
• Differs from native human bFGF by only two amino
acids
• Essentially identical angiogenic properties
• Enrollment
• Screening physical exam and labs
• Exercise or dipyridamole stress test with dual isotope
imaging
• Cardiac MRI with cardiac function and collateral flow
determinations
• Ophthalmologic exam
• Quality of Life questionnaire
Inclusion Criteria
• Severe CAD with inducible ischemia on
stress test
• No optimal revascularization option
• Normal routine laboratory screening
• Willingness and ability to complete all
components of the study and its follow-up
• Signed informed consent
Exclusion Criteria
• Class IV CHF or EF < 20%
• MI < 3 months
• New or unstable angina < 3
wks
• CABG < 6 months
• PTCA or TMR < 6 months
• Significant arrhythmias
• Pacemaker or AICD
• LBBB
• Severe valvular heart
disease
• Restrictive or
hypertrophic
cardiomyopathy
• Known AVMs
• TIA or CVA < 6 mths
• DM with end-organ
damage
• Cr Cl < 80 ml/min or
proteinuria
• Cancer within 10 years
Drug Administration
• Intracoronary Infusion
• Left and Right heart catheterizations
• 10 minute infusions of bFGF into the RCA and
LM (or the major supplying bypass graft)
• Intravenous Infusion
• Left heart catheterization (if not done within 6
mths)
• 10 minute infusion into a peripheral vein
Follow-Up Protocol
• Clinic visits with routine blood tests at day 6,
day 14 and at 1, 2, 6 and 12 months
• Repeat stress test and MRI scans at 1 month
• Subsequent exams only if indicated
• Repeat Eye exams at 2 and 12 months
• Repeat Quality of Life questionnaire at 2
months