Open Access is an initiative that aims to make scientific research freely available to all. To date our community has made over 100 million downloads. It’s based on principles of collaboration, unobstructed discovery, and, most importantly, scientific progression. As PhD students, we found it difficult to access the research we needed, so we decided to create a new Open Access publisher that levels the playing field for scientists across the world. How? By making research easy to access, and puts the academic needs of the researchers before the business interests of publishers.
We are a community of more than 103,000 authors and editors from 3,291 institutions spanning 160 countries, including Nobel Prize winners and some of the world’s most-cited researchers. Publishing on IntechOpen allows authors to earn citations and find new collaborators, meaning more people see your work not only from your own field of study, but from other related fields too.
To purchase hard copies of this book, please contact the representative in India:
CBS Publishers & Distributors Pvt. Ltd.
www.cbspd.com
|
customercare@cbspd.com
Dept. of Internal Medicine, AngiologyMedical University Innsbruck,, Austria
*Address all correspondence to:
1. Introduction
Cardiovascular diseases still represent the leading cause of death in the western world. Coronary artery disease (CAD) affects over 5% of the US population and is responsible for nearly 7 millions of in-patient procedures every year (1). Peripheral arterial disease (PAD), with a prevalence of 3-30%, also is a very common disease (2). PAD can be classified according to the severity of clinical symptoms into Fontaine-stages I-IV. In Fontaine-stage I patients are clinically asymptomatic and this stage is the most common form of PAD (70-80%). Patients with Fontaine II (10-20%) suffer from intermittent claudication that might be life-style limiting and require therapy like percutaneous transluminal angioplasty (PTA). A smaller portion (3-5%) of PAD patients have critical limb ischemia (CLI) characterized by rest pain (Fontaine III) or ulcer (Fontaine IV). The incidence of CLI is estimated to be 500-1000 per 1 Million but prognosis is very bad. One year after diagnosis only 45 % of patients are alive without major amputation and effective revascularization with relieve of symptoms can only be achieved in 25% of patients. Therefore, new therapeutic strategies are urgently needed for these patients.
Generation of new blood vessels can be achieved by sprouting of new vessels out of the pre-existing capillary plexus (angiogenesis), by generation of new arteries (arteriogenesis) or by circulating endothelial progenitor cells (vasculogenesis) (3). Several factors have been characterized which induce growth of new blood vessels, the most prominent being vascular endothelial growth factor (VEGF) and members of the fibroblast growth factor (FGF) family. In animal models of hindlimb and myocardial ischemia beneficial effects on blood perfusion and blood vessel density of these (and other) factors as well as of progenitor cells could be demonstrated (4) (5). This therapeutic concept was named “therapeutic angiogenesis“ and application of angiogenic factors via gene therapy vectors like plasmids or adenoviruses was superior to protein application probably due to longer lasting expression of respective cytokines.
3. Therapeutic angiogenesis: gene therapy trials in PAD patients
Due to promising data in preclinical studies the concept of therapeutic angiogenesis was tested in clinical trials in PAD and CAD patients. While first phase-1 studies in PAD patients were promising phase-II studies in patients with intermittent claudication were negative (see summary for clinical trials in PAD patients in table 1). Obviously especially patients with CLI respond to therapy with angiogenic factors and gene therapy seems to have a benefit over therapy with respective proteins.
The last years several placebo-controlled double-blinded trials have been published which showed beneficial effects in CLI patients after i.m.plasmid gene therapy with VEGF, FGF1 or hepatocyte growth factor (HGF) (Tab. 2). Especially the TALISMAN study could demonstrate a reduction in amputation rate. Regarding potential adverse effects these studies did not show evidence of increase of cancer rates or proliferative retinopathy. (21)
The positive results of the TALISMAN study on reduction of amputation rate and mortality in CLI patients by FGF1 gene therapy was the basis for a large phase 3 study. Over 500 CLI patients were treated with FGF1 gene therapy versus placebo. The primary outcome after 12 months was a combined endpoint of major amputation above the ankle or death. The results of this trial, called TAMARIS, were presented at the AHA meeting, November 2010, in Chicago, USA. There was no difference in mortality and major amputation between FGF1 gene therapy and placebo. Also secondary endpoints were not different and there was no increase in occurrence of malignant diseases or proliferative retinopathy. The difference between the positive results in phase 2 (TALISMAN) and negative results in phase 3 (TAMARIS) were explained by a type-1 error (finding by chance) in the phase-2 study. It will be interesting to see the publication of the TAMARIS trial to further discuss the reasons for this negative trial and the different results of this trial and phase 2 TALISMAN.
4. Therapeutic angiogenesis: gene therapy trials in CAD patients
Several angiogenic cytokines (especially VEGF-A and FGF4) were tested in patients with severe chronic CAD in whom revascularization by angioplasty or bypass surgery was no further option and who suffered from severe angina and limited exercise tolerance (for recent excellent reviews please also see (26, 27). As observed in PAD-patients phase-1 and phase-2 studies showed feasibility of these therapies and signs of bioactivity. Specifically, gene therapy (adenovirus, administered intra-coronary) with FGF4 showed a trend toward increase in exercise time in the AGENT (Angiogenic Gene Therapy) trial and the subsequent phase-2 AGENT 2 trial showed reduction in reversible perfusion defect size (however not statistically significant due to one outlier in the placebo group). The phase-3 AGENT 3 and AGENT 4 trials were stopped early when an interim analysis of the AGENT 3 cohort indicated that the primary endpoint (change in exercise treadmill test after 12 weeks) was unlikely to differ between FGF4 and placebo. A pooled analysis of AGENT 3 and 4 however revealed that women and patients >65 years with severe angina had statistically significant improvement in angina class and exercise test. A subsequent gene therapy trial in women with CAD was stopped, apparently due to slow enrollment.
Also VEGF gene therapy was tested in CAD patients in randomized studies. In the Kuopio Angiogenesis Trial (KAT) no difference in restenosis rate (primary endpoint) was observed after intra-coronary VEGF gene therapy (plasmid liposome or adenovirus), however after 6 months increased myocardial perfusion was found after adenoviral VEGF application. In the Euroinject One study VEGF plasmid was injected intra- myocardial into regions with perfusion defects. The primary endpoint, improvement of myocardial perfusion was not reached, however, VEGF improved regional wall motion score.
For summary of controlled trials on therapeutic angiogenesis in CAD patients see table 3.
The negative results of phase-3 trials AGENT and TAMARIS raise important question about therapeutic angiogenesis and gene therapy. What is the reason that therapeutic angiogenesis with factors like VEGF or FGF did improve outcomes in a variety of animal models but failed to improve human disease? One explanation is that often young animals were used
Trial
Factor
Patients
Effects
Reference
Phase-1/2
VEGF-2 plasmid i.myoc.
n=19; CCS3-4, RA, NR
Improvement angina class
Losordo et al 2002(28)
AGENT Phase-1/2
Adenovirus-FGF4; i.coro.
n=79; CCS2-3
Trend toward increase in exercise time
Grines et al 2002 (29)
AGENT 2 Phase-2
Adenovirus-FGF4; i.coro.
n=52; CCS2-4, RA, NR
Improvement of perfusion defects by SPECT (not sign.)
Grines et al 2003 (30)
VIVA Phase-2
VEGF protein i.coro., i.v.
n=178; RA, NR
Improvement angina class, no effect on exercise time
Henry et al 2003(31)
KAT Phase-2
VEGF-165 adenovirus or plasmid/liposome i.coro.
n=103; stable angina
Improvement in myocardial perfusion, no effect on restenosis
Hedman et al 2003(32)
EUROINJECT-ONE Phase-2
VEGF-165 Plasmid i.myoc.
n=80; CCS3-4, RA, NR
Improvement wall motion, no effect on myocardial perfusion
Kastrup et al 2005(33)
REVASC Open label
Adenovirus VEGF-121 i.myoc. (thoracotomy)
n=65; CCS2-4, RA, NR
Improvement in exercise time at 26 weeks, not at 12 weeks
Stewart et al 2006(34)
AGENT3/4 Phase-3
Adenovirus-FGF4; i.coro.
n=532; CCS2-4, RA, (AGENT4: NR)
Enrollment stopped after interim analysis, primary endpoint negative. Improvement angina and exercise time in women, older patients with severe symptoms
Henry et al 2007(35)
Table 3.
Controlled trials on therapeutic angiogenesis in CAD patients. (Abbreviations: CCS, Canadian cardiovascular society; i.coro., intra-coronary; i.myoc., intra-myocardial; i.v., intra-venous; NR, nonrevascularizable; RA, refractory stable angina;)
whereas in humans usually patients of older age and a variety of co-morbidities are affected. Additionally, transfection efficacy of gene therapy vectors, even of adenoviruses, is lower in humans than in animals and precise dosing of vectors is not possible due to the fact that transgene expression cannot be precisely quantified. Another open question is the selection of gene therapy vectors-adenoviruses usually have adverse effects, especially immunogenicity, whereas plasmid vectors are safe but have low transfection efficacy. Dose and duration of therapy is another question. One dose of a vector that expresses the transgene for days to weeks might not be sufficient to treat a disease that evolved over the time-course of many years. Also patient selection might have been a problem: usually “no-option” patients were included in these studies, e.g. patients with large ischemic ulcers in the case of CLI (Rutherford class 6). Maybe patients with less severe disease, like patients with Rutherford class 5 or patients who would be treated additionally with revascularization procedures would benefit more from therapeutic angiogenesis. Endpoint selection is another critical point as some functional outcome measurements like severity of angina are subjective and might be affected by the placebo effect. Cell-based therapies have shown positive effects in CAD and PAD (36, 37)-maybe a combined therapeutic strategy consisting of cell application and gene therapy with angiogenic factors would result in better outcome.
2.NorgrenL.HiattW. R.DormandyJ. A.NehlerM. R.HarrisK. A.FowkesF. G.BellK.CaporussoJ.Durand-ZaleskiI.KomoriK.et al.2007 Inter-Society Consensus for the Management of Peripheral Arterial Disease (TASC II). Eur J Vasc Endovasc Surg 33 Suppl 1:S175 .
3.Carmeliet,2000 Mechanisms of angiogenesis and arteriogenesis. Nat Med 6:389-395.
4.LosordoD. W.Dimmeler2004 2004. Therapeutic angiogenesis and vasculogenesis for ischemic disease: part I: angiogenic cytokines. Circulation1092487 -2491.
5.LosordoD. W.Dimmeler2004 2004. Therapeutic angiogenesis and vasculogenesis for ischemic disease: part II: cell-based therapies. Circulation10926922697 .
6.IsnerJ. M.BaumgartnerI.RauhG.SchainfeldR.BlairR.ManorO.RazviS.SymesJ. F.1998 Treatment of thromboangiitis obliterans (Buerger’s disease) by intramuscular gene transfer of vascular endothelial growth factor: preliminary clinical results. J Vasc Surg28964973 ; discussion 973-965.
7.BaumgartnerI.PieczekA.ManorO.BlairR.KearneyM.WalshK.IsnerJ. M.1998 Constitutive expression of phVEGF165 after intramuscular gene transfer promotes collateral vessel development in patients with critical limb ischemia. Circulation9711141123 .
8.MannM. J.WhittemoreA. D.DonaldsonM. C.BelkinM.ConteM. S.PolakJ. F.OravE. J.EhsanA.Dell’AcquaG.DzauV. J.1999 Ex-vivo gene therapy of human vascular bypass grafts with E2F decoy: the PREVENT single-centre, randomised, controlled trial. Lancet35414931498 .
9.LazarousD. F.UngerE. F.EpsteinS. E.StineA.ArevaloJ. L.ChewE. Y.QuyyumiA. A.2000 Basic fibroblast growth factor in patients with intermittent claudication: results of a phase I trial. Journal of the American College of Cardiology3613391344 .
10.CooperL. T.Jr HiattW. R.CreagerM. A.RegensteinerJ. G.CasscellsW.IsnerJ. M.CookeJ. P.HirschA. T.2001 Proteinuria in a placebo-controlled study of basic fibroblast growth factor for intermittent claudication. Vasc Med6235 -239.
11.ComerotaA. J.ThromR. C.MillerK. A.HenryT.ChronosN.LairdJ.SequeiraR.KentC. K.BacchettaM.GoldmanC.et al.2002 Naked plasmid DNA encoding fibroblast growth factor type 1 for the treatment of end-stage unreconstructible lower extremity ischemia: preliminary results of a phase I trial. J Vasc Surg35930936 .
12.LedermanR. J.MendelsohnF. O.AndersonR. D.SaucedoJ. F.TenagliaA. N.HermillerJ. B.HillegassW. B.Rocha-SinghK.MoonT. E.WhitehouseM. J.et al.2002 Therapeutic angiogenesis with recombinant fibroblast growth factor-2 for intermittent claudication (the TRAFFIC study): a randomised trial. Lancet35920532058 .
13.RajagopalanS.MohlerE. R.2003 Lederman, R.J., Mendelsohn, F.O., Saucedo, J.F., Goldman, C.K., Blebea, J., Macko, J., Kessler, P.D., Rasmussen, H.S., et al. 2003. Regional angiogenesis with vascular endothelial growth factor in peripheral arterial disease: a phase II randomized, double-blind, controlled study of adenoviral delivery of vascular endothelial growth factor 121 in patients with disabling intermittent claudication. Circulation10819331938 .
14.ShyuK. G.ChangH.WangB. W.Kuan2003 Intramuscular vascular endothelial growth factor gene therapy in patients with chronic critical leg ischemia. Am J Med 114:85-92.
15.MatyasL.SchulteK. L.DormandyJ. A.NorgrenL.SowadeO.GrotzbachG.Palmer-KazenU.RubanyiG. M.Wahlberg2005 2005. Arteriogenic gene therapy in patients with unreconstructable critical limb ischemia: a randomized, placebo-controlled clinical trial of adenovirus 5-delivered fibroblast growth factor-4. Hum Gene Ther1612021211 .
16.ConteM. S.BandykD. F.ClowesA. W.MonetaG. L.SeelyL.LorenzT. J.NaminiH.HamdanA. D.RoddyS. P.BelkinM.et al.2006 Results of PREVENT III: a multicenter, randomized trial of edifoligide for the prevention of vein graft failure in lower extremity bypass surgery. J Vasc Surg43742751 ; discussion 751.
17.MorishitaR.AokiM.HashiyaN.MakinoH.YamasakiK.AzumaJ.SawaY.MatsudaH.KanedaY.Ogihara2004. Safety evaluation of clinical gene therapy using hepatocyte growth factor to treat peripheral arterial disease. Hypertension44203209 .
18.MaruiA.TabataY.KojimaS.YamamotoM.TambaraK.NishinaT.SajiY.InuiK.HashidaT.YokoyamaS.et al.2007 A novel approach to therapeutic angiogenesis for patients with critical limb ischemia by sustained release of basic fibroblast growth factor using biodegradable gelatin hydrogel: an initial report of the phase I-IIa study. Circ J7111811186 .
19.GrossmanP. M.MendelsohnF.HenryT. D.HermillerJ. B.LittM.SaucedoJ. F.WeissR. J.KandzariD. E.KleimanN.AndersonR. D.et al.2007 Results from a phase II multicenter, double-blind placebo-controlled study of Del-1 (VLTS-589) for intermittent claudication in subjects with peripheral arterial disease. Am Heart J153874880 .
20.RajagopalanS.OlinJ.DeitcherS.PieczekA.LairdJ.GrossmanP. M.GoldmanC. K.Mc EllinK.KellyR.Chronos2007. Use of a constitutively active hypoxia-inducible factor-1alpha transgene as a therapeutic strategy in no-option critical limb ischemia patients: phase I dose-escalation experience. Circulation11512341243 .
21.TongersJ.RoncalliJ. G.LosordoD. W.2008 Therapeutic angiogenesis for critical limb ischemia: microvascular therapies coming of age. Circulation118916 .
22.MakinenK.ManninenH.HedmanM.MatsiP.MussaloH.AlhavaE.Yla-Herttuala2002. Increased vascularity detected by digital subtraction angiography after VEGF gene transfer to human lower limb artery: a randomized, placebo-controlled, double-blinded phase II study. Mol Ther6127133 .
23.KusumantoY. H.van WeelV.MulderN. H.SmitA. J.van denDungen. J. J.HooymansJ. M.SluiterW. J.TioR. A.QuaxP. H.GansR. O.et al.2006 Treatment with intramuscular vascular endothelial growth factor gene compared with placebo for patients with diabetes mellitus and critical limb ischemia: a double-blind randomized trial. Hum Gene Ther17683691 .
24.NikolS.BaumgartnerI.Van BelleE.DiehmC.VisonaA.CapogrossiM. C.Ferreira-MaldentN.GallinoA.WyattM. G.WijesingheL. D.et al.2008 Therapeutic angiogenesis with intramuscular NV1FGF improves amputation-free survival in patients with critical limb ischemia. Mol Ther16972 -978.
25.PowellR. J.SimonsM.MendelsohnF. O.DanielG.HenryT. D.KogaM.MorishitaR.AnnexB. H.2008 Results of a double-blind, placebo-controlled study to assess the safety of intramuscular injection of hepatocyte growth factor plasmid to improve limb perfusion in patients with critical limb ischemia. Circulation1185865 .
26.GuptaR.TongersJ.LosordoD. W.2009 Human studies of angiogenic gene therapy. Circ Res105724736 .
27.BeoharN.RappJ.PandyaS.LosordoD. W.2010 Rebuilding the damaged heart: the potential of cytokines and growth factors in the treatment of ischemic heart disease. J Am Coll Cardiol5612871297 .
28.LosordoD. W.ValeP. R.HendelR. C.MillikenC. E.FortuinF. D.CummingsN.SchatzR. A.AsaharaT.IsnerJ. M.KuntzR. E.2002 Phase 1/2 placebo-controlled, double-blind, dose-escalating trial of myocardial vascular endothelial growth factor 2 gene transfer by catheter delivery in patients with chronic myocardial ischemia. Circulation10520122018 .
29.GrinesC. L.WatkinsM. W.HelmerG.PennyW.BrinkerJ.MarmurJ. D.WestA.RadeJ. J.MarrottP.HammondH. K.et al.2002 Angiogenic Gene Therapy (AGENT) trial in patients with stable angina pectoris. Circulation1051291 -1297.
30.GrinesC. L.WatkinsM. W.MahmarianJ. J.IskandrianA. E.RadeJ. J.MarrottP.PrattC.Kleiman2003 2003. A randomized, double-blind, placebo-controlled trial of Ad5FGF-4 gene therapy and its effect on myocardial perfusion in patients with stable angina. J Am Coll Cardiol4213391347 .
31.HenryT. D.AnnexB. H.Mc KendallG. R.AzrinM. A.LopezJ. J.GiordanoF. J.ShahP. K.WillersonJ. T.BenzaR. L.BermanD. S.et al.2003 The VIVA trial: Vascular endothelial growth factor in Ischemia for Vascular Angiogenesis. Circulation10713591365 .
32.HedmanM.HartikainenJ.SyvanneM.StjernvallJ.HedmanA.KivelaA.VanninenE.MussaloH.KauppilaE.SimulaS.et al.2003 Safety and feasibility of catheter-based local intracoronary vascular endothelial growth factor gene transfer in the prevention of postangioplasty and in-stent restenosis and in the treatment of chronic myocardial ischemia: phase II results of the Kuopio Angiogenesis Trial (KAT). Circulation1072677 -2683.
33.KastrupJ.JorgensenE.RuckA.TagilK.GlogarD.RuzylloW.BotkerH. E.DudekD.DrvotaV.HesseB.et al.2005 Direct intramyocardial plasmid vascular endothelial growth factor-A165 gene therapy in patients with stable severe angina pectoris A randomized double-blind placebo-controlled study: the Euroinject One trial. J Am Coll Cardiol45982 -988.
34.StewartD. J.HiltonJ. D.ArnoldJ. M.GregoireJ.RivardA.ArcherS. L.Charbonneau 2006. Angiogenic gene therapy in patients with nonrevascularizable ischemic heart disease: a phase 2 randomized, controlled trial of AdVEGF(121) (AdVEGF121) versus maximum medical treatment. Gene Ther 13:1503-1511.
35.HenryT. D.GrinesC. L.WatkinsM. W.DibN.BarbeauG.MoreadithR.AndrasfayT.EnglerR. L.2007 Effects of Ad5FGF-4 in patients with angina: an analysis of pooled data from the AGENT-3 and AGENT-4 trials. J Am Coll Cardiol5010381046 .
36.SchachingerV.ErbsS.ElsasserA.HaberboschW.HambrechtR.HolschermannH.YuJ.CortiR.MatheyD. G.HammC. W.et al.2006 Intracoronary bone marrow-derived progenitor cells in acute myocardial infarction. N Engl J Med35512101221 .
37.WalterD. H.KrankenbergH.BalzerJ. O.KalkaC.BaumgartnerI.SchluterM.TonnT.SeegerF.DimmelerS.Lindhoff-LastE.et al.2011 Intraarterial Administration of Bone Marrow Mononuclear Cells in Patients With Critical Limb Ischemia: A Randomized-Start, Placebo-Controlled Pilot Trial (PROVASA). Circ Cardiovasc Interv42637 .
Written By
Rudolf Kirchmair
Submitted: 11 November 2010Published: 22 June 2011