Fig. 4. Patient N.U. 76 yrs, OCT scan (Optopol SD device). It shows the resolution of fluid 3 years after repeated intravitreal bevacizumab treatment.

Fig. 5. Patient R.K. 74 yrs., fundus photography at baseline before combination treatment (bevacizumab + PDT) showing exudation and hemorrhage.

Treatment of Neovascular Age Related Macular Degeneration 137

Fig. 8. Patient R.K. 74 yrs OCT scan (Optopol SD device). It shows resolution of fluid 3 years after initial combination treatment of intravitreal bevacizumab and photodynamic therapy

In summary we can conclude that new emerging therapies for nAMD for the first time in history managed to revert the natural history of disease. In significant number of patients some improvement could be achieved while in a majority of patients the treatment resulted in maintenance of visual acuity. However the significant burden of repeated intravitreal injections, increased risks of ocular and possibly systemic side effects and decreased patients' compliance lead to further visual loss over time. Also some patients do not respond to the available treatments favorably. So the need for new and more efficient drugs in terms of better functional outcome and reduced need for retreatment is fully justified. VEGF-Trap-Eye is pending approval and it may show to be more potent and requiring less treatment. Also combination of present treatment modalities should further be evaluated. Hopefully with better understanding of the genes responsible for different variants of nAMD we could either employ some form of genetic therapy or we can adjust already available treatments according to a certain genotype in order to achieve most favorable

[1] Macular Photocoagulation Study Group. Argon laser photocoagulation for neovascular

[2] Macular Photocoagulation Study Group. Subfoveal neovascular lesions in age-related

photocoagulation study. Arch Ophthalmol 1991;109(9):1242-57.

maculopathy. Five-year results from randomized clinical trials. Arch Ophthalmol

macular degeneration. Guidelines for evaluation and treatment in the macular

followed by repeated bevacizumab treatment.

results.

**5. References**

1991;109(8):1109-14.

Fig. 6. Patient R.K. 74 yrs, early and late phase of fluorescein angiography at baseline before combination treatment (bevacizumab+PDT). It shows marginal hemorrhage and leakage of dye from the CNV.

Fig. 7. Patient R.K. 74 yrs OCT scan (Zeiss Stratus II device) at baseline before combination treatment. It shows accumulation of intraretinal and subretinal fluid.

Fig. 6. Patient R.K. 74 yrs, early and late phase of fluorescein angiography at baseline before combination treatment (bevacizumab+PDT). It shows marginal hemorrhage and leakage of

Fig. 7. Patient R.K. 74 yrs OCT scan (Zeiss Stratus II device) at baseline before combination

treatment. It shows accumulation of intraretinal and subretinal fluid.

dye from the CNV.

Fig. 8. Patient R.K. 74 yrs OCT scan (Optopol SD device). It shows resolution of fluid 3 years after initial combination treatment of intravitreal bevacizumab and photodynamic therapy followed by repeated bevacizumab treatment.

In summary we can conclude that new emerging therapies for nAMD for the first time in history managed to revert the natural history of disease. In significant number of patients some improvement could be achieved while in a majority of patients the treatment resulted in maintenance of visual acuity. However the significant burden of repeated intravitreal injections, increased risks of ocular and possibly systemic side effects and decreased patients' compliance lead to further visual loss over time. Also some patients do not respond to the available treatments favorably. So the need for new and more efficient drugs in terms of better functional outcome and reduced need for retreatment is fully justified. VEGF-Trap-Eye is pending approval and it may show to be more potent and requiring less treatment. Also combination of present treatment modalities should further be evaluated. Hopefully with better understanding of the genes responsible for different variants of nAMD we could either employ some form of genetic therapy or we can adjust already available treatments according to a certain genotype in order to achieve most favorable results.

#### **5. References**

Treatment of Neovascular Age Related Macular Degeneration 139

[18] Boyer DS, Heier JS, Brown DM et al. A Phase IIIb study to evaluate the safety of

[19] Meyer CH, Eter N, Holz FD. SUSTAIN Study Group. Ranibizumab in Patients With

[20] Brown DM, Wang OW, Scott LC. HORIZON extension trial of Ranibizumab for wet

[21] Kabbinavare F, Hurwitz HI, Fehrenbacher L et al. Phase II, randomized trial

[23] Michels S S, Rosenfeld PJ, Puliafito CA et al. Systemic bevacizumab (Avastin) therapy

uncontrolled open-label clinical study. Ophthalmology 2005;112(6):1035-47. [24] Rosenfeld PJ, Moshfeghi AA, Puliafito CA. Optical coherence tomography findings

macular degeneration. Ophthalmic Surg Lasers Imaging 2005;36(4):331-5. [25] Shahar J, Avery RL, Heilwell G et al. Electrophysiologic and retinal penetration studies following intravitreal injection of bevacizumab (Avastin). Retina 2006;26(3):262-9. [26] AveryRL, Pieramici DJ, Rabena MD et al. Intravitreal bevacizumab (Avastin) for neovascular age-related macular degeneration. Ophthalmology 2006;113:363-72. [27] Spaide RF, Laud K, Fine HF et al. Intravitreal bevacizumab treatment of choroidal

[28] Aisenbrey S, Ziemssen F, Volker M et al. Intravitreal bevacizumab (Avastin) for occult

[29] Lazic R, Gabric N. Intravitreally administered bevacizumab (Avastin) in minimally

[31] Gamulescu MA, Radeck V, Lustinger B, Fink B, Helbig H. Bevacizumab versus

[32] Landa G, Made W, Doshi BV at al. Comparative study of intravitreal bevacizumab

related macular degeneration. Ophthalmologica 2009;223(6):370-5.

degeneration. Graefes Arch Clin Exp Ophthalmol 2007;245(1):68-73. [30] Arevalo JF, Sánchez JG, Wu L et al. Intravitreal Bevacizumab for Subfoveal Choroidal

in patients with metastatic colorectal cancer. J Clin Oncol 2003; 21:60-5. [22] Hurwitz H, Fehrenbacher L, Novotny W et al. Bevacizumab plus irinotecan,

Ophthalmology 2009;116(9):1731-9.

2008;49: E-Abstract 273.

Georgia, USA.

2004;350:2335-42.

2006;26:383-90.

tisku.

Clin Exp Ophthalmol 2007;245(7):941-8.

Ophthalmol 2010;30(3):261-6.

ranibizumab in subjects with neovascular age-related macular degeneration.

Subfoveal Choroidal Neovascularization Secondary to Age-Related Macular Degeneration. Interim Results From the Sustain Trial. Invest Ophthalmol Vis Sci

AMD: subanalysis of year 1 results. AAO/SOE Joint Annual Meeting 2008, Atlanta,

comparing bevacizumab plus fluorouracil (FU)/leucovorin (LV) with FU/LV alone

fluorouracil, and leucovorin for metastatic colorectal cancer. N Engl J Med

for neovascular age-related macular degeneration. Twelve-week results of an

after an intravitreal injection of bevacizumab (avastin) for neovascular age-related

neovascularization secondary to age-related macular degeneration. Retina

choroidal neovascularisation in age-related macular degeneration. Graefes Arch

classic and occult choroidal neovascularization secondary to age-related macular

Neovascularization in Age-Related Macular Degeneration at Twenty-four Months: The Pan-American Collaborative Retina Study Group.Ophthalmology 2010;Članak u

ranibizumab in the treatment of exudative age-related macular degeneration. Int

(Avastin) versus ranibizumab (Lucentis) in the treatment of neovascular age-

[3] Schmidt-Erfurth U, Laqua H, Schlotzer-Schrehard U, Viestenz A, Naumann GO.

[4] Fingar VH, Wieman TJ, Wiehle SA, Cerrito PB.The role of microvascular damage in

[5] Treatment of age-related macular degeneration with photodynamic therapy (TAP) Study

[6] Treatment of Age-Related Macular Degeneration with Photodynamic Therapy Study

[7] Azab M, Boyer DS, Bressler NM et al. Verteporfin therapy of subfoveal minimally classic

[8] Bressler NM. Verteporfin therapy of subfoveal choroidal neovascularization in age-

[10] McLeod D. Foveal translocation for exudative age related macular degeneration. Br J

[11] Akduman L, Karavellas MP, MacDonald JC, Olk RJ, Freeman WR.Macular

[12] Graroudas ES, Adamis AP, Cunningham ET Jr et al. Pegaptanib for neovascular age-

[13] Ferrara N, Damico L, Shams N et al. Development of ranibizumab, an anti-vascular

[14] Rosenfeld PJ, Brown DM, Heier JS et al. MARINA Study Group. Ranibizumab for neovascular age-related macular degeneration. N Engl J Med 2006;355:1419-31. [15] Brown DM, Kaiser PK, Michels M et al. ANCHOR Study Group. Ranibizumab versus

[16] Regillo CD, Brown DM, Abraham P et al. Randomized, double-masked, sham-

[17] Lalwani GA, Rosenfeld PJ, Fung AE et al. A variable-dosing regimen with intravitreal

related macular degeneration. N Engl J Med 2004;351(27):2805-16.

age-related macular degeneration. Retina 2006;26:859-70.

PIER Study year 1. Am J Ophthalmol 2008;145(2): 239-48.

PrONTO study. Am J Ophthalmol 2009;148(1):43-58.

and leukocyte adhesion.Cancer Res 1992;52(18):4914-21.

clinical trials--TAP report.Arch Ophthalmol 1999;117:1329-45.

clinical trials--TAP report 2. Arch Ophthalmol 2001;119:198-207.

a randomized clinical trial. Arch Ophthalmol 2005;123(4): 448-57.

Ophthalmol 2002;120:835-44.

2003;121:1253-68.

2006;355:1432-44.

Ophthalmol. 2000;84:344–345.

macular degeneration. Retina. 1999;19:418–423.

Histopathological changes following photodynamic therapy in human eyes. Arch

photodynamic therapy: the effect of treatment on vessel constriction, permeability,

Group. Photodynamic therapy of subfoveal choroidal neovascularization in agerelated macular degeneration with verteporfin: one-year results of 2 randomized

Group. Photodynamic therapy of subfoveal choroidal neovascularization in agerelated macular degeneration with verteporfin: two-year results of 2 randomized

choroidal neovascularization in age-related macular degeneration: 2-year results of

related macular degeneration: two-year results of a randomized clinical trial including lesions with occult with no classic choroidal neovascularizationverteporfin in photodynamic therapy report 2. Am J Ophthalmol 2002;133:168-9. [9] Barbazetto I, Burdan A, Bressler NM et al. Photodynamic therapy of subfoveal choroidal

neovascularization with verteporfin: fluorescein angiographic guidelines for evaluation and treatment--TAP and VIP report No. 2. Arch Ophthalmol

translocation with retinotomy and retinal rotation for exudative age-related

endothelial growth factor antigen binding fragment, as therapy for neovascular

verteporfin for neovascular age-related macular degeneration. N Engl J Med

controlled trial of ranibizumab for neovascular age-related macular degeneration:

ranibizumab for neovascular age-related macular degeneration: year 2 of the

Treatment of Neovascular Age Related Macular Degeneration 141

[51] Jaakkola A, Heikkonen J, Tommila P et al. Strontium plaque brachyterapy for

[52] Finger PT, Berson A, Ng T, Szechter A. Ophthalmic plaque radiotherapy for age-

[53] Avila MP, Farah ME, Duprat JP et al. Twelve month short-term safety and visual

[54] Kuppermann BD. Epimacular brachytherapy for the treatment of choroidal

[55] Augustin AJ, Schmidt-Erfurth U. Verteporfin therapy combined with intravitreal

[56] Spaide RF, Sorenson J, Maranan L. Photodynamic therapy with verteporfin combined

[57] Chan WM, Lai TY, Wong AL, Tong JP, Liu DT, Lam DS.Combined photodynamic

[58] Schadlu R, Kymes SM, Apte RS. Combined photodynamic therapy and intravitreal

[59] Lazic R, Gabric N.Verteporfin therapy and intravitreal bevacizumab combined and

[60] Bakri SJ, Couch SM, McCannel CA, Edwards AO. Same-day triple therapy with

[61] Kaiser PK, Boyer DS, Garcia R et al. Verteporfin photodynamic therapy combined with

[62] Shah GK, Sang DN, Hughes MS. Verteporfin combination regimens in the treatment of neovascular age-related macular degeneration. Retina 2009;29(2):133-48. [63] Maier M, Haas K, Feucht N et al. Photodynamic therapy with verteporfin combined

[64] Ahmadieh H, Taei R, Soheilian M, Riazi-Esfahani M, Ahadi H. Single-session

age-related macular degeneration. Eur J Ophthalmol 2008;18(2):297-300.

Ophthalmology 112 (4), 2005;567-573.

Ophthalmol 1999; 127:170-177.

Ophthalmol. 2009; 93: 305-309.

the Retina sub-specialty meeting, AAO, 2008.

study. Br J Ophthalmol 2006;90(3):337-41.

Ophthalmology 2007;114(6):1179-85.

Ophthalmology 2009;116(4):747-55.

Monatsbl Augenheilkd 2008;225(7):653-9.

2007;245(11):1667-72.

macular degeneration.Ophthalmology 2006;113:14 –22.

neovascularization. Ophthalmology 2005;112(2):301-4.

related macular degeneration Retina 2009;29(5):573-8.

exudative age related macular degeneration: 3 year results of a randomized study.

related macular degeneration associated with subretinal neovascularization. Am J

acuity results from a multicentre prospective study of epiretinal strontium-90 brachytherapy with bevacizumab for the treatment of subfoveal choroidal neovascularization secondary to age-related macular degeneration. Br J

neovascularization associated with age related macular degeneration. Presented at

triamcinolone in all types of choroidal neovascularization due to age-related

with intravitreal injection of triamcinolone acetonide for choroidal

therapy and intravitreal triamcinolone injection for the treatment of subfoveal choroidal neovascularisation in age related macular degeneration: a comparative

triamcinolone for neovascular age-related macular degeneration: effect of initial visual acuity on treatment response..Graefes Arch Clin Exp Ophthalmol

alone in choroidal neovascularization due to age-related macular degeneration.

photodynamic therapy, intravitreal dexamethasone, and bevacizumab in wet age-

intravitreal bevacizumab for neovascular age-related macular degeneration.

with intravitreal injection of bevacizumab for occult and classic CNV in AMD. Klin

photodynamic therapy combined with intravitreal bevacizumab for neovascular

[33] Fong DS, Custis P, Howes J, Hsu JW. Intravitreal Bevacizumab and Ranibizumab for

[34] Shaha AR, Del Priore LV. Duration of action of intravitreal ranibizumab and

[35] CATT Research Group, Martin DF, Maguire MG, Ying GS, Grunwald JE, Fine SL, Jaffe

[36] Holash J, Davis S, PapadopoulosN et al. VEGF-Trap: a VEGF blocker with potent

[37] Nguyen QD, Shah SM, Hafiz G et al. A phase I trial of an IV-administered vascular

[38] Heiner JS. VEGF Trap Eye Phase III Trial Results. VIEW 1 results.Paper presented at:Angiogenesis, Exudation and Degeneration 2011; Miami, Florida. [39] Schmidt-Erfurt U. VEGF Trap Eye Phase III Trial Results. VIEW 2 results.Paper presented at: Angiogenesis, Exudation and Degeneration 2011; Miami, Florida. [40] Reich S, Fosnot J, Akiko K et al. Small interfering RNA (siRNA) targeting VEGF

[41] Tolentino MJ, Brucker AJ, Fosnot J et al. Intravitreal injection of vascular endothelial

[42] Shen J, Samul R, Silva RL et al. Suppression of ocular neovascularization with siRNA

[43] Mabjeesh NJ, Amir S. Hypoxia-inducible factor (HIF) in human tumorigenesis. Histol

[45] Robinsnon DR, Wu YM, Lin SF. The protein tyrosine kinase family of the human

[48] Dawson DW, Volpret OV, Gillis P at al. Vascular permeability factor/vascular

[49] StellmachV, Crawford SE, Zhou W, Bouck N. Prevention of ischemia-induced

[50] Mori K., Gehlbach P, Yamamoto S at al. AAV-mediated gene transfer of pigment

inhibitor PTK787/ZK222584 improves ischemia-induced retinopathy in mice.

endothelial growth factor and the significance of microvascular hyperpermeability

retinopathy by the natural ocular antiangiogenic agent pigment epithelium-derived

epithelium-derived growth factor inhibits choroidal neovascularization. Invest

[46] Blume-Jensen P, Hunter T. Oncogenic kinase signalling. Nature 2001;411:355–65. [47] Maier P, Unsoeld AS, Junker B at al. Intravitreal injection of specific receptor kinase

targeting VEGF receptor 1. Gene Ther 2006;13(3):225-34.

Graefes Arch Clin Exp Ophthalmol 2005;243(6):593-600.

in angiogenesis. Curr Top Microbiol Immunol 1999;237:97-132.

[44] Hunter T. Signaling: 2000 and beyond. Cell 2000;100:113–27.

factor. Proc Natl Acad Sci USA 2001;98:2593-7.

Ophthalmol Vis Sci 2002;43:1994-2000.

antitumor effects. Proc Natl Acad Sci USA 2002;99(17):11393-8.

Ophthalmology 2010;117(2):298-302.

degeneration.N Engl J Med. 2011; 364(20):1897-908.

J Ophthalmol 2009;93(8):1027-32.

2006;113(9):1522.

2003;9:210-6.

2004;24(4):660.

Histopathol 2007;22(5):559-72.

genome. Oncogene 2000;19:5548–57.

Age-Related Macular Degeneration: A Multicenter, Retrospective Study.

bevacizumab in exudative AMD eyes based on macular volume measurements. Br

GJ. Ranibizumab and bevacizumab for neovascular age-related macular

endothelial growth factor trap for treatment in patients with choroidal neovascularization due to age-related macular degeneration. Ophthalmology

effectively inhibits ocular neovascularization in a mouse model. Molecular Vision

growth factor small interfering RNA inhibits growth and leakage in a nonhuman primate, laser-induced model of choroidal neovascularization. Retina

[65] Ladewig MS, Karl SE, Hamelmann V et al. Combined intravitreal bevacizumab and photodynamic therapy for neovascular age-related macular degeneration. Graefes Arch Clin Exp Ophthalmol 2008;246(1):17-25.

**8**

*Turkey*

**Re-Treatment Strategies for Neovascular**

*1Gazi University, School of Medicine, Department of Ophthalmology, Ankara 2Yenisehir State Hospital, Department of Ophthalmology, Kahramanmaras*

Age-related macular degeneration (AMD) is a leading cause of severe, irreversible vision impairment in developed countries (Friedman et al., 2004; Klein et al., 1992). Although an estimated 80% of patients with AMD have the non-neovascular form, the neovascular form is responsible for almost 90% of severe visual loss (visual acuity 20/200 or worse) resulting from AMD (Ferris et al., 1984). There was no effective treatment for most of the neovascular AMD lesions till 2004. By this time, the role of vascular endothelial growth factor (VEGF) in neovascular AMD became obvious and anti-VEGF agents emerged for this purpose. Pegaptanib sodium intravitreal injection (Macugen; [OSI] Eyetech, New York, NY, 2004), ranibizumab intravitreal injection (Lucentis, Genentech, Inc., South San Francisco, CA, 2006) were the FDA approved treatments for AMD. The first report of intravitreal bevacizumab (Avastin; Genentech, Inc., South San Francisco, CA) administration for neovascular AMD was published in 2005 (Rosenfeld et al., 2005). By early 2006, off-label intravitreal bevacizumab was used by many retina specialists as a first-line therapy for neovascular AMD because of the low cost of this drug. Wholesale prices of the medications range from \$1950 per dose for ranibizumab and \$995 per dose for pegaptanib, to approximately \$50 per

MARINA and ANCHOR were the first studies showing level 1 evidence for the effect of ranibizumab for the treatment of neovascular ARMD (Brown et al., 2009; Rosenfeld et al., 2006a; Rosenfeld et al., 2006b). These studies have shown that 33-40% of the eyes with neovascular AMD treated with ranibizumab gained 15 letters or more (Brown et al., 2009; Rosenfeld et al., 2006a). However these studies used monthly injections of the drug for 24 months. This is the most effective treatment but almost impossible to apply in routine applications both for patients and doctors. Additionally monthly injections will cost so much that treatment cannot be afforded neither by patients nor the social security systems.

**2. How to decrease the number of injections without compromising visual**

PIER study was the first study investigating the results of less frequent dosing regimens with ranibizumab (3-monthly) for the treatment of AMD (Regillo et al., 2008). However

dose for bevacizumab (Champan & Beckey, 2006; Web, 2008).

**1. Introduction**

**acuity?**

**AMD: When to Treat? When to Stop?**

Sengul Ozdek1 and Mehmet Cuneyt Ozmen2

### **Re-Treatment Strategies for Neovascular AMD: When to Treat? When to Stop?**

Sengul Ozdek1 and Mehmet Cuneyt Ozmen2 *1Gazi University, School of Medicine, Department of Ophthalmology, Ankara 2Yenisehir State Hospital, Department of Ophthalmology, Kahramanmaras Turkey*

#### **1. Introduction**

142 Age Related Macular Degeneration – The Recent Advances in Basic Research and Clinical Care

[65] Ladewig MS, Karl SE, Hamelmann V et al. Combined intravitreal bevacizumab and

[66] Oner A, Gumus K, Arda H, Yuce Y, Karakucuk S, Mirza E. Pattern electroretinographic

[68] Mataix J, Palacios E, Carmen DM, Garcia-Pous M, Navea A .Combined ranibizumab

An Option For Improving Treatment Efficiency. Retina 2010;Članak u tisku. [69] Costagliola C, Romano MR, Rinaldi M et al. Low fluence rate photodynamic therapy

[70] Debefve E, Pegaz B, Ballini JP, van den Bergh H.Combination therapy using

age-related macular degeneration. Doc Ophthalmol 2009;119(1):37-42. [67] Rudnisky, C.J.Liu, C.,Ng, M. Weis, E. Tennant, M.T.S. Intravitreal bevacizumab alone

Arch Clin Exp Ophthalmol 2008;246(1):17-25.

after 1 year of follow-up. Retina 2010;30:548-54.

degeneration.Br J Ophthalmol 2010;94(2):180-4.

Photochem Photobiol 2009;85(6):1400-8.

photodynamic therapy for neovascular age-related macular degeneration. Graefes

results after photodynamic therapy alone and photodynamic therapy in combination with intravitreal bevacizumab for choroidal neovascularization in

versus combined verteporfin photodynamic therapy and intravitreal bevacizumab for choroidal neovascularization in age-related macular degeneration: Visual acuity

and photodynamic therapy to treat exudative age-related macular degeneration.

combined with intravitreal bevacizumab for neovascular age-related macular

verteporfin and ranibizumab; optimizing the timing in the CAM model.

Age-related macular degeneration (AMD) is a leading cause of severe, irreversible vision impairment in developed countries (Friedman et al., 2004; Klein et al., 1992). Although an estimated 80% of patients with AMD have the non-neovascular form, the neovascular form is responsible for almost 90% of severe visual loss (visual acuity 20/200 or worse) resulting from AMD (Ferris et al., 1984). There was no effective treatment for most of the neovascular AMD lesions till 2004. By this time, the role of vascular endothelial growth factor (VEGF) in neovascular AMD became obvious and anti-VEGF agents emerged for this purpose. Pegaptanib sodium intravitreal injection (Macugen; [OSI] Eyetech, New York, NY, 2004), ranibizumab intravitreal injection (Lucentis, Genentech, Inc., South San Francisco, CA, 2006) were the FDA approved treatments for AMD. The first report of intravitreal bevacizumab (Avastin; Genentech, Inc., South San Francisco, CA) administration for neovascular AMD was published in 2005 (Rosenfeld et al., 2005). By early 2006, off-label intravitreal bevacizumab was used by many retina specialists as a first-line therapy for neovascular AMD because of the low cost of this drug. Wholesale prices of the medications range from \$1950 per dose for ranibizumab and \$995 per dose for pegaptanib, to approximately \$50 per dose for bevacizumab (Champan & Beckey, 2006; Web, 2008).

MARINA and ANCHOR were the first studies showing level 1 evidence for the effect of ranibizumab for the treatment of neovascular ARMD (Brown et al., 2009; Rosenfeld et al., 2006a; Rosenfeld et al., 2006b). These studies have shown that 33-40% of the eyes with neovascular AMD treated with ranibizumab gained 15 letters or more (Brown et al., 2009; Rosenfeld et al., 2006a). However these studies used monthly injections of the drug for 24 months. This is the most effective treatment but almost impossible to apply in routine applications both for patients and doctors. Additionally monthly injections will cost so much that treatment cannot be afforded neither by patients nor the social security systems.

#### **2. How to decrease the number of injections without compromising visual acuity?**

PIER study was the first study investigating the results of less frequent dosing regimens with ranibizumab (3-monthly) for the treatment of AMD (Regillo et al., 2008). However

Re-Treatment Strategies for Neovascular AMD: When to Treat? When to Stop? 145

Although PRN treatment regimen may reduce the number of intravitreal injections and allow the treatment plan to be individualized, it may still require monthly visits to specialized centers. In contrast to mandated monthly injections, patients treated with PRN strategies may develop multiple recurrences of CNV activity over time. Recurrent intra- or subretinal fluid could potentially induce progressive, cumulative dysfunction of the neural retina, resulting in a decreased ability of the retina to recover despite further treatment. There are some other treatment regimens like "treat and extend" and "individualized injection intervals" regimens which aim to individualize the treatment plan and decrease the number of injections per year, but at the same time attempts to achieve a fluid-free macula and decrease the number of visits (Brown & Regillo, 2007; Gupta et al., 2010; Hörster et al.,

In an attempt to minimize the number of intravitreal injections, office visits, and ancillary testing, a "treat and extend" regimen (TER) was first put forth by Bailey Freund, (unpublished data, February 2006) and then adopted by others (Gupta et al., 2010; Oubraham et al., 2011). A typical TER starts with monthly injections until the signs of exudation have resolved with confirmation by OCT. The treatment interval is then sequentially lengthened by 1 to 2 weeks as long as there are no signs of recurrent exudation. When recurrent exudation is detected on a follow-up visit, the treatment interval is reduced to the prior interval. Treatment is rendered at every visit but the time between visits is individualized based on a given patient's response to treatment. As with traditional PRN regimens, the goal is to maintain an exudation-free macula with the fewest number of injections. This approach also may allow for a significant reduction in

In a study by Gupta et al., eyes with neovascular AMD experienced significant visual improvement when managed with intravitreal ranibizumab using a TER. This treatment approach also was associated with significantly fewer patient visits, injections, and direct annual medical cost compared with monthly injections such as in the phase III clinical trials (Gupta et al., 2010). The interval was individualized for each patient in an attempt to maintain an exudation-free macula. In another study comparing the results of this treatment regimen with the standard PRN regimen, patients reinjected by the TER had a far better visual outcome than PRN regimen but needed more injections (Oubraham et al., 2011).

Another individualized treatment strategy that aims to avoid recurrent CNV activity in addition to reducing the number of injections and visits may be to perform the injection immediately prior to the next recurrence. This would require the ability to determine or predict the recurrence interval for an individual patient. A treatment schedule can be obtained for some of the cases after a couple of years of experience with PRN regimen (Hörster et al., 2011). Knowledge of individual recurrence interval times may allow for the

**2.2 Treatment regimens other than PRN**

2011; Oubraham et al., 2011; Spaide, 2007).

**2.2.1 Treat & extend dosing regimen**

**2.2.2 Individualized injection intervals**

development of an individualized treatment plan (Figure 1).

office visits and tests.

PIER study revealed disappointing results showing loss of early gained vision during 3 monthly injection period. Other prospective studies, PrONTO and SUSTAIN, investigated the efficacy of PRN (pro re nata; as needed) treatment regimen. Results from these studies suggested that fewer injections by using a variable dosing regimen with OCT will most likely result in visual acuity improvements similar to the results from the phase III trials which used monthly injections (Holz et al., 2011; Lalwani et al., 2009; Rosenfeld et al., 2006b)

#### **2.1 What is "PRN" treatment regimen and what are the most reliable criteria for treatment decision?**

PRN treatment regimen is a treatment schedule which allows treatment only if the lesion is active. The aim of the PRN treatment is to avoid monthly injections and to decrease the number of injections as much as possible while preserving the vision gained in the loading period (first three months).

The key point in PRN treatment is assessment of the activity of the lesion to decide for additional treatments. It is obvious that a totally fibrotic yellow scarring lesion without any hemorrhage around, only late staining of the scar tissue in fluorescein angiography (FA), and no subretinal or intraretinal fluid in optical coherence tomography (OCT) with stable vision for a long time does not need any treatment. On the other side of the spectrum, a lesion with subretinal hemorrhages all around, significant late leakage in FA and a considerable subretinal or intraretinal fluid in OCT and deteriorating vision recently needs treatment with no doubt. However most of the lesions are in between these two ends of the spectrum especially during the course of anti-VEGF treatments and may be difficult to decide if any further treatment is necessary or not.

Until recently, the presence or absence of fluorescein leakage and the angiographic appearance of the lesion were the main criteria for the decision to treat neovascular ARMD and re-treat using PDT or anti-VEGF therapy (Schmidt-Erfurth et al., 2007). Within the last decade OCT has emerged and enhanced our understanding in many central retinal diseases. For AMD, OCT appears to be useful for evaluating the responses of the retina and retinal pigment epithelium (RPE) to the treatment (Cohen et al., 2007; Eter & Spaide, 2005; Fung et al., 2007; Krebs et al., 2008; Lalwani et al., 2009; Salinas-Alamán et al., 2005; Schmidt-Erfurth et al., 2007; van Velthoven et al., 2006;). Clinical trials have shown that in the two thirds of patients requiring ranibizumab therapy because of recurrent neovascularization, OCT seemed to detect early anatomic changes in the macula before any vision loss (observation during the extension trials of phase I-II studies by P. Rosenfeld: unpublished data). The PrONTO study was initiated to explore the use of OCT as the basis for a less frequent variable dosing regimen with ranibizumab (Fung et al., 2007; Lalwani et al., 2009). This study used some criteria for retreatment including an OCT based parameter (an increase in central OCT thickness of at least 100 mm) during the first year. However they made an amendment to their OCT based criteria in the second year. They changed the retreatment criteria to include any qualitative change in the appearance of the OCT images that suggested recurrent fluid in the macula. These qualitative changes included the appearance of retinal cysts or subretinal fluid or an enlargement of a PED. Any of these qualitative changes alone was sufficient to permit retreatment (Lalwani et al., 2009).

#### **2.2 Treatment regimens other than PRN**

144 Age Related Macular Degeneration – The Recent Advances in Basic Research and Clinical Care

PIER study revealed disappointing results showing loss of early gained vision during 3 monthly injection period. Other prospective studies, PrONTO and SUSTAIN, investigated the efficacy of PRN (pro re nata; as needed) treatment regimen. Results from these studies suggested that fewer injections by using a variable dosing regimen with OCT will most likely result in visual acuity improvements similar to the results from the phase III trials which used monthly injections (Holz et al., 2011; Lalwani et al., 2009; Rosenfeld et al., 2006b)

**2.1 What is "PRN" treatment regimen and what are the most reliable criteria for**

PRN treatment regimen is a treatment schedule which allows treatment only if the lesion is active. The aim of the PRN treatment is to avoid monthly injections and to decrease the number of injections as much as possible while preserving the vision gained in the loading

The key point in PRN treatment is assessment of the activity of the lesion to decide for additional treatments. It is obvious that a totally fibrotic yellow scarring lesion without any hemorrhage around, only late staining of the scar tissue in fluorescein angiography (FA), and no subretinal or intraretinal fluid in optical coherence tomography (OCT) with stable vision for a long time does not need any treatment. On the other side of the spectrum, a lesion with subretinal hemorrhages all around, significant late leakage in FA and a considerable subretinal or intraretinal fluid in OCT and deteriorating vision recently needs treatment with no doubt. However most of the lesions are in between these two ends of the spectrum especially during the course of anti-VEGF treatments and may be difficult to

Until recently, the presence or absence of fluorescein leakage and the angiographic appearance of the lesion were the main criteria for the decision to treat neovascular ARMD and re-treat using PDT or anti-VEGF therapy (Schmidt-Erfurth et al., 2007). Within the last decade OCT has emerged and enhanced our understanding in many central retinal diseases. For AMD, OCT appears to be useful for evaluating the responses of the retina and retinal pigment epithelium (RPE) to the treatment (Cohen et al., 2007; Eter & Spaide, 2005; Fung et al., 2007; Krebs et al., 2008; Lalwani et al., 2009; Salinas-Alamán et al., 2005; Schmidt-Erfurth et al., 2007; van Velthoven et al., 2006;). Clinical trials have shown that in the two thirds of patients requiring ranibizumab therapy because of recurrent neovascularization, OCT seemed to detect early anatomic changes in the macula before any vision loss (observation during the extension trials of phase I-II studies by P. Rosenfeld: unpublished data). The PrONTO study was initiated to explore the use of OCT as the basis for a less frequent variable dosing regimen with ranibizumab (Fung et al., 2007; Lalwani et al., 2009). This study used some criteria for retreatment including an OCT based parameter (an increase in central OCT thickness of at least 100 mm) during the first year. However they made an amendment to their OCT based criteria in the second year. They changed the retreatment criteria to include any qualitative change in the appearance of the OCT images that suggested recurrent fluid in the macula. These qualitative changes included the appearance of retinal cysts or subretinal fluid or an enlargement of a PED. Any of these qualitative changes alone was sufficient to permit retreatment (Lalwani et

**treatment decision?**

al., 2009).

period (first three months).

decide if any further treatment is necessary or not.

Although PRN treatment regimen may reduce the number of intravitreal injections and allow the treatment plan to be individualized, it may still require monthly visits to specialized centers. In contrast to mandated monthly injections, patients treated with PRN strategies may develop multiple recurrences of CNV activity over time. Recurrent intra- or subretinal fluid could potentially induce progressive, cumulative dysfunction of the neural retina, resulting in a decreased ability of the retina to recover despite further treatment. There are some other treatment regimens like "treat and extend" and "individualized injection intervals" regimens which aim to individualize the treatment plan and decrease the number of injections per year, but at the same time attempts to achieve a fluid-free macula and decrease the number of visits (Brown & Regillo, 2007; Gupta et al., 2010; Hörster et al., 2011; Oubraham et al., 2011; Spaide, 2007).

#### **2.2.1 Treat & extend dosing regimen**

In an attempt to minimize the number of intravitreal injections, office visits, and ancillary testing, a "treat and extend" regimen (TER) was first put forth by Bailey Freund, (unpublished data, February 2006) and then adopted by others (Gupta et al., 2010; Oubraham et al., 2011). A typical TER starts with monthly injections until the signs of exudation have resolved with confirmation by OCT. The treatment interval is then sequentially lengthened by 1 to 2 weeks as long as there are no signs of recurrent exudation. When recurrent exudation is detected on a follow-up visit, the treatment interval is reduced to the prior interval. Treatment is rendered at every visit but the time between visits is individualized based on a given patient's response to treatment. As with traditional PRN regimens, the goal is to maintain an exudation-free macula with the fewest number of injections. This approach also may allow for a significant reduction in office visits and tests.

In a study by Gupta et al., eyes with neovascular AMD experienced significant visual improvement when managed with intravitreal ranibizumab using a TER. This treatment approach also was associated with significantly fewer patient visits, injections, and direct annual medical cost compared with monthly injections such as in the phase III clinical trials (Gupta et al., 2010). The interval was individualized for each patient in an attempt to maintain an exudation-free macula. In another study comparing the results of this treatment regimen with the standard PRN regimen, patients reinjected by the TER had a far better visual outcome than PRN regimen but needed more injections (Oubraham et al., 2011).

#### **2.2.2 Individualized injection intervals**

Another individualized treatment strategy that aims to avoid recurrent CNV activity in addition to reducing the number of injections and visits may be to perform the injection immediately prior to the next recurrence. This would require the ability to determine or predict the recurrence interval for an individual patient. A treatment schedule can be obtained for some of the cases after a couple of years of experience with PRN regimen (Hörster et al., 2011). Knowledge of individual recurrence interval times may allow for the development of an individualized treatment plan (Figure 1).

Re-Treatment Strategies for Neovascular AMD: When to Treat? When to Stop? 147

In conclusion, re-injections of ranibizumab shortly prior to a recurrence may avoid recurrent leakage and fluid accumulation, as well as further growth of the CNV lesion size. Therefore, avoiding recurrent CNV activity with prophylactic injections may protect the neural retina from additional damage and improve the long-term prognosis. However, this approach requires the ability to determine individual recurrence intervals with a couple of years of

All treatment regimens mentioned above aims to reduce injection numbers without compromising the patients visual acuity. Yet there is not a consensus about the objective

Definition of an active lesion should not be done only with the OCT based criteria. We believe that, other parameters like visual acuity, presence of hemorrhage associated with the lesion, lesion size and FA staining pattern (when needed) are all also important for assessment of neovascular AMD activity. The PrONTO study put some of these parameters together and created their criteria for retreatment. Retreatment with ranibizumab was

SUSTAIN study used only VA and OCT criteria for retreatment decision. We believe that these are very well prepared criteria, however, some of the items could be changed and

A new clinical activity scoring (AS) is proposed to assess activity of lesions, to quantify the activity for statistical purposes in clinical studies and to standardize the re-treatment protocols during the course of anti-VEGF treatments of neovascular AMD lesions. This may

The proposed AS is based on the well known and widely used signs and findings of active

performed only if one of the following occurred in PrONTO study (Fung et al., 2007):

**2.3 The need for an activity scoring for re-treatment of exudative AMD**

experience with PRN regimen.

criteria of an active neovascular CNV lesion.

3. New-onset classic neovascularization,

4. New macular hemorrhage.

be a basis for treatment regimens.

neovascular AMD (Table 1):

4. Change in size of the lesion,

5. FA staining pattern (when needed).

3. Change in vision;

**3.1 Methods**

1. An increase in central OCT thickness of at least 100 mm,

some new criteria could be added to make it more reliable.

1. Presence of subretinal or intraretinal fluid in OCT, 2. Presence of hemorrhage associated with the lesion,

a. Objective measured visual acuity (VA)

b. Subjective vision (what patient feels about his vision)

2. A loss of five letters in conjunction with recurrent fluid by OCT,

**3. A clinical activity scoring for re-treatment of exudative AMD**

Fig. 1. A, Baseline, VA: 44 letters, 1st injection. B, 1st month, 53 letters, 2nd injection. C, 2nd month, 54 letters, 3rd injection. D, 51 letters, no treatment. E, 4th month, 46 letters, 4th injection. F, 5th month, 47 letters, no treatment. G, 6th month, 46 letters, 5th injection. H, 7th month, 42 letters, 6th injection. I, 8th month, 50 letters, no treatment. J, 8th month, 44 letters, 7th injection. K, 9th month, 48 letters, no treatment. L, 10th month, 38 letters, 8th injection. According to the data, this patient has a recurrence pattern of 8 weeks, thus needs retreatment every 7 weeks.

A retrospective study in University of Cologne analyzed the recurrence intervals of patients undergoing anti-VEGF therapy for neovascular AMD to determine whether predictable, regular recurrence patterns were present for individual patients (Hörster et al., 2011). The paper reported that, all recurrences occurred at regular intervals in 41% of the eyes and the recurrence interval time may vary between individuals (Hörster et al., 2011).

In conclusion, re-injections of ranibizumab shortly prior to a recurrence may avoid recurrent leakage and fluid accumulation, as well as further growth of the CNV lesion size. Therefore, avoiding recurrent CNV activity with prophylactic injections may protect the neural retina from additional damage and improve the long-term prognosis. However, this approach requires the ability to determine individual recurrence intervals with a couple of years of experience with PRN regimen.

#### **2.3 The need for an activity scoring for re-treatment of exudative AMD**

All treatment regimens mentioned above aims to reduce injection numbers without compromising the patients visual acuity. Yet there is not a consensus about the objective criteria of an active neovascular CNV lesion.

Definition of an active lesion should not be done only with the OCT based criteria. We believe that, other parameters like visual acuity, presence of hemorrhage associated with the lesion, lesion size and FA staining pattern (when needed) are all also important for assessment of neovascular AMD activity. The PrONTO study put some of these parameters together and created their criteria for retreatment. Retreatment with ranibizumab was performed only if one of the following occurred in PrONTO study (Fung et al., 2007):

SUSTAIN study used only VA and OCT criteria for retreatment decision. We believe that these are very well prepared criteria, however, some of the items could be changed and some new criteria could be added to make it more reliable.

#### **3. A clinical activity scoring for re-treatment of exudative AMD**

A new clinical activity scoring (AS) is proposed to assess activity of lesions, to quantify the activity for statistical purposes in clinical studies and to standardize the re-treatment protocols during the course of anti-VEGF treatments of neovascular AMD lesions. This may be a basis for treatment regimens.

#### **3.1 Methods**

146 Age Related Macular Degeneration – The Recent Advances in Basic Research and Clinical Care

Fig. 1. A, Baseline, VA: 44 letters, 1st injection. B, 1st month, 53 letters, 2nd injection. C, 2nd month, 54 letters, 3rd injection. D, 51 letters, no treatment. E, 4th month, 46 letters, 4th injection. F, 5th month, 47 letters, no treatment. G, 6th month, 46 letters, 5th injection. H, 7th month, 42 letters, 6th injection. I, 8th month, 50 letters, no treatment. J, 8th month, 44 letters, 7th injection. K, 9th month, 48 letters, no treatment. L, 10th month, 38 letters, 8th injection. According to the data, this patient has a recurrence pattern of 8 weeks, thus needs re-

A retrospective study in University of Cologne analyzed the recurrence intervals of patients undergoing anti-VEGF therapy for neovascular AMD to determine whether predictable, regular recurrence patterns were present for individual patients (Hörster et al., 2011). The paper reported that, all recurrences occurred at regular intervals in 41% of the eyes and the

recurrence interval time may vary between individuals (Hörster et al., 2011).

treatment every 7 weeks.

The proposed AS is based on the well known and widely used signs and findings of active neovascular AMD (Table 1):

	- a. Objective measured visual acuity (VA)
	- b. Subjective vision (what patient feels about his vision)

Re-Treatment Strategies for Neovascular AMD: When to Treat? When to Stop? 149

2. **Amount of hemorrhage**: The amount of hemorrhage associated with the lesion (in ophthalmoscopy, colored fundus photography or FA) was noted and if there is any hemorrhage at the beginning it was scored as 2. If there is no hemorrhage it was scored as 0, if it was decreased it was scored as 1, if it was the same, scored as 2, and if it was

a. *Objective VA* is measured with ETDRS and noted as a baseline and scored as 1. If there is a decrease in vision (any line or ≥5 letters loss) it was scored as 2 and if

there is any increase in vision (any line or ≥5 letters gain) it was scored as 0. b. *Subjective vision* (what patient feels about his vision): Patient's feeling about any change in his vision was also asked and noted as subjective vision which was scored as 0 if he feels better, 2 if he feels worse and 1 if he did not feel any change

4. **FA staining pattern**: No staining or window defect (0), staining of scar tissue or PED (1)

5. **The area of the lesion** (mm2): It was measured in FA and the baseline area (or no change) was scored as 1, at least 10% (of the original area) increase was scored as 2 and

Records of the patients at the 1st month visit after the treatment were also noted and all of the above parameters were again noted, so that an AS is calculated both before and after the treatment. AS could range between 0 and 14. Change in AS after the treatment was analyzed

It can be hypothesized that, the more active the lesion the more it may respond to the anti-VEGF therapy. A possible correlation between pretreatment AS and posttreatment decrease

Eyes with favorable treatment response (two or more units of decrease in AS) and unfavorable treatment response (one unit or no decrease in AS) were separated and the mean pre and posttreatment AS were calculated for both groups. The mean AS of these two groups were compared by using Mann-Whitney U test. At this stage, a cut off point for AS was searched to determine the eyes that need treatment. Sensitivity, specificity, negative and positive predictive values of the AS were calculated to determine the cut off point for AS

In this section, the results of an ongoing study is presented to better understand the activity

A total of 52 eyes with neovascular AMD were involved in the study. Mean age of the patients was 72.7 (52-89), mean visual acuity (logMAR) was 0.68 (0-1.6) and mean lesion

Pretreatment mean AS of eyes was 7.4 (ranged between 3 and 10) which decreased significantly to 4.2 after treatment (p<0.001, Wilcoxon). There was a significant positive correlation between the pretreatment AS of eyes and the posttreatment decrease in AS

in AS was investigated by using Pearson correlation test to test this hypothesis.

increased scored as 3. 3. Visual assessment:

(baseline).

and late leakage (2) were noted.

by using Wilcoxon signed rank test.

at least 10% decrease was scored as 0.

which will be used to decide on re-treatments.

area was 8.9 mm2 (0.6-33mm2) before treatment.

(Pearson correlation coefficient: 0.534, p<0.001, Figure 2).

**3.2 Results**

scoring.

Table 1. Clinical Activity Scoring for neovascular AMD lesions

Apart from FA staining pattern, all of the other assessments are based on the changes (samebaseline/increased/decreased) in each parameter and given a number to define the activity. At the end of the assessment, given numbers are summed and an activity score is calculated.

This scoring has been used in a group of neovascular AMD patients all of which have been involved in a prospective study for intravitreal bevacizumab (IVB) in our clinic (Şekeryapan et al., 2011). All of them received IVB monotherapy. The reports of the patients were reviewed retrospectively and demographic features as well as lesion characteristics of the patients were noted. AS of all of the lesions were calculated according to the following criteria:

1. **OCT:** OCT was performed using the Humphrey model 3000 (Zeiss-Humphrey Instruments, San Leandro, CA). After pupil dilatation, six consecutive 6mm long scans containing 128 axial profiles (A-scans) at equally spaced angular orientations in a radial spoke pattern centered on the fovea (known as Fast Macular Thickness Protocol) were obtained for each eye. Using Retinal Thickness Mapping Software mean retinal thickness value which was measured in the central disc with a diameter of 1000µm in the center of the macula was used as central foveal thickness (CFT). The fluid pattern (subretinal / intraretinal diffuse / cystoid / pigment epithelial detachment - PED) was also noted. Only the CFT was used as an activity parameter in AS and at least 10% increase or decrease in CFT was accepted as a decrease or increase. The amount of fluid at the beginning was scored as 2. It was scored as "0" if there is no fluid, "1" if there is a decrease and "3 if there is an increase in CFT.

No hemorrhage 0 decreased 1 Same amount 2 increased 3

None 0 Decreased 1 Any amount at beginning / Stable 2 Increased 3

Increased 0 No change 1 Decreased 2

Increased 0 No change 1 Decreased 2

No staining/window defect 0 Staining of scar tissue/PED 1 Late leakage 2

Decreased 0 Beginning size / Stable 1 Increased 2

Apart from FA staining pattern, all of the other assessments are based on the changes (samebaseline/increased/decreased) in each parameter and given a number to define the activity. At the end of the assessment, given numbers are summed and an activity score is calculated. This scoring has been used in a group of neovascular AMD patients all of which have been involved in a prospective study for intravitreal bevacizumab (IVB) in our clinic (Şekeryapan et al., 2011). All of them received IVB monotherapy. The reports of the patients were reviewed retrospectively and demographic features as well as lesion characteristics of the patients were noted. AS of all of the lesions were calculated according to the following

1. **OCT:** OCT was performed using the Humphrey model 3000 (Zeiss-Humphrey Instruments, San Leandro, CA). After pupil dilatation, six consecutive 6mm long scans containing 128 axial profiles (A-scans) at equally spaced angular orientations in a radial spoke pattern centered on the fovea (known as Fast Macular Thickness Protocol) were obtained for each eye. Using Retinal Thickness Mapping Software mean retinal thickness value which was measured in the central disc with a diameter of 1000µm in the center of the macula was used as central foveal thickness (CFT). The fluid pattern (subretinal / intraretinal diffuse / cystoid / pigment epithelial detachment - PED) was also noted. Only the CFT was used as an activity parameter in AS and at least 10% increase or decrease in CFT was accepted as a decrease or increase. The amount of fluid at the beginning was scored as 2. It was scored as "0" if there is no fluid, "1" if there is a

**PARAMETER GRADING SCORE**

Table 1. Clinical Activity Scoring for neovascular AMD lesions

decrease and "3 if there is an increase in CFT.

**Hemorrhage**

**OCT**

Amount of hemorrhage associated with the lesion

Subretinal fluid / retinal thickening / PED

**Visual assessment**

**Visual assessment**

Staining pattern

**Size of the lesion**  Lesion area in FA

**Objective**

**Subjective**

**FA**

criteria:

Records of the patients at the 1st month visit after the treatment were also noted and all of the above parameters were again noted, so that an AS is calculated both before and after the treatment. AS could range between 0 and 14. Change in AS after the treatment was analyzed by using Wilcoxon signed rank test.

It can be hypothesized that, the more active the lesion the more it may respond to the anti-VEGF therapy. A possible correlation between pretreatment AS and posttreatment decrease in AS was investigated by using Pearson correlation test to test this hypothesis.

Eyes with favorable treatment response (two or more units of decrease in AS) and unfavorable treatment response (one unit or no decrease in AS) were separated and the mean pre and posttreatment AS were calculated for both groups. The mean AS of these two groups were compared by using Mann-Whitney U test. At this stage, a cut off point for AS was searched to determine the eyes that need treatment. Sensitivity, specificity, negative and positive predictive values of the AS were calculated to determine the cut off point for AS which will be used to decide on re-treatments.

#### **3.2 Results**

In this section, the results of an ongoing study is presented to better understand the activity scoring.

A total of 52 eyes with neovascular AMD were involved in the study. Mean age of the patients was 72.7 (52-89), mean visual acuity (logMAR) was 0.68 (0-1.6) and mean lesion area was 8.9 mm2 (0.6-33mm2) before treatment.

Pretreatment mean AS of eyes was 7.4 (ranged between 3 and 10) which decreased significantly to 4.2 after treatment (p<0.001, Wilcoxon). There was a significant positive correlation between the pretreatment AS of eyes and the posttreatment decrease in AS (Pearson correlation coefficient: 0.534, p<0.001, Figure 2).

Re-Treatment Strategies for Neovascular AMD: When to Treat? When to Stop? 151

decrease was statistically significant (p<0.001, Figure 4). The mean pretreatment AS was 5.4 (3-6) in group 2 which decreased to 4 (1-6) after treatment. Although the decrease was less than that in group 1, it was still statistically significant (p=0.034, Figure 4). The mean

Groups

Favorable Response Unfavorable Response Total

Fig. 3. The pretreatment AS was statistically significantly higher in favorable treatment response group than unfavorable treatment response group (Mann Whitney U test p=0.003).

was 45% (table 3). These may be assumed as indicators for accuracy of AS.

AS ≥7 37 4 41 AS <7 6 5 11 Total 43 9 52 Positive predictive value, 37 of 41 = 90%; negative predictive value, 5 of 11 = 45%, sensitivity,

Table 3. Accuracy of activity score (AS) in predicting therapeutic outcome of treatment in

Sensitivity of AS (ratio of eyes with a favorable response and an AS of 7 or more to the total number of eyes with favorable response) was 86% and, specificity of AS (ratio of eyes with an unfavorable response and an AS of less than 7 to the total number of eyes with unfavorable response) was 56% with a cut-off point of 7 (table 3). Positive predictive value (ratio of eyes with AS of 7 or more and a favorable response to the total number of eyes with AS of 7 or more) of AS was 90% and negative predictive value (ratio of eyes with AS of less than 7 and an unfavorable response to the total number of eyes with AS of less than 7) of AS

Favorable response Unfavorable response

decrease in AS was 3.5 in group one and 1.4 in group two (p=0.003, Figure 5).

Mean Pretreatment AS +/- 2 SE

8,5

8,0

7,5

7,0

6,5

6,0

5,5

5,0

4,5

37 of 43 = 86%, specificity, 5 of 9 = 56%.

neovascular AMD.

Difference in AS (Pre-Post)

Fig. 2. Correlation between the pretreatment AS of eyes and the post-treatment decrease in AS (Pearson correlation coefficient: 0.534, p<0.001)

To define a cut-off point a group of eyes with favorable treatment responses is formed by separating those who had at least 2 point decrease in AS and named the favorable response group. The remaining eyes formed the unfavorable response group. The pretreatment mean AS was 7.5 (6-10) in favorable response group and 6 (3-7) in unfavorable response group. The pretreatment AS in favorable treatment response group was statistically significantly higher than those of unfavorable treatment response groups (p=0.003, Figure 3).

The sensitivity, specificity, negative and positive predictive values of the AS with different cut off points were calculated (table 2) and an AS of 7 was found to be most suitable as a cutoff point for further analysis.

Table 2. Predictive values, sensitivity and specificity of AS for detecting favorable treatment response (2 or more decrease in AS)

Eyes with an AS of 7 or more (group 1, highly active group, n=41) were separated from those less than 7 (group 2, less active group, n=11) and a subgroup analysis was done. The mean AS in group 1 was 7.8 (7-10) before treatment and 4.3 (1-10) after treatment. The

Fig. 2. Correlation between the pretreatment AS of eyes and the post-treatment decrease in

To define a cut-off point a group of eyes with favorable treatment responses is formed by separating those who had at least 2 point decrease in AS and named the favorable response group. The remaining eyes formed the unfavorable response group. The pretreatment mean AS was 7.5 (6-10) in favorable response group and 6 (3-7) in unfavorable response group. The pretreatment AS in favorable treatment response group was statistically significantly

The sensitivity, specificity, negative and positive predictive values of the AS with different cut off points were calculated (table 2) and an AS of 7 was found to be most suitable as a cut-

> Pretreatment AS≥ 7

Pretreatment AS≥ 8

higher than those of unfavorable treatment response groups (p=0.003, Figure 3).

Pretreatment AS≥ 6

Positive predictive value 85,10% 90,20% 100,00% Negative predictive value 40,00% 45,50% 25,70% Sensitivity 93,00% 86,00% 39,50% Specificity 22,20% 55,60% 100,00%

Table 2. Predictive values, sensitivity and specificity of AS for detecting favorable treatment

Eyes with an AS of 7 or more (group 1, highly active group, n=41) were separated from those less than 7 (group 2, less active group, n=11) and a subgroup analysis was done. The mean AS in group 1 was 7.8 (7-10) before treatment and 4.3 (1-10) after treatment. The

Difference in AS (Pre-Post)

Pretreatment AS

off point for further analysis.

response (2 or more decrease in AS)

12

10

8

6

4

2

AS (Pearson correlation coefficient: 0.534, p<0.001)

decrease was statistically significant (p<0.001, Figure 4). The mean pretreatment AS was 5.4 (3-6) in group 2 which decreased to 4 (1-6) after treatment. Although the decrease was less than that in group 1, it was still statistically significant (p=0.034, Figure 4). The mean decrease in AS was 3.5 in group one and 1.4 in group two (p=0.003, Figure 5).

Fig. 3. The pretreatment AS was statistically significantly higher in favorable treatment response group than unfavorable treatment response group (Mann Whitney U test p=0.003).

Sensitivity of AS (ratio of eyes with a favorable response and an AS of 7 or more to the total number of eyes with favorable response) was 86% and, specificity of AS (ratio of eyes with an unfavorable response and an AS of less than 7 to the total number of eyes with unfavorable response) was 56% with a cut-off point of 7 (table 3). Positive predictive value (ratio of eyes with AS of 7 or more and a favorable response to the total number of eyes with AS of 7 or more) of AS was 90% and negative predictive value (ratio of eyes with AS of less than 7 and an unfavorable response to the total number of eyes with AS of less than 7) of AS was 45% (table 3). These may be assumed as indicators for accuracy of AS.

Positive predictive value, 37 of 41 = 90%; negative predictive value, 5 of 11 = 45%, sensitivity, 37 of 43 = 86%, specificity, 5 of 9 = 56%.

Table 3. Accuracy of activity score (AS) in predicting therapeutic outcome of treatment in neovascular AMD.

Cut-off AS

Fig. 4. Pretreatment and posttreatment mean AS of eyes in group 1 (with an AS of 7 or more, highly active group) and in group 2 (with an AS of less than 7, less active group).

Re-Treatment Strategies for Neovascular AMD: When to Treat? When to Stop? 153

Neovascular AMD activity is an important factor to determine if it should be treated or not. It is important not to over-treat these eyes to avoid from injection and drug related complications as well as high cost of the treatment. There is no standard protocol for the treatment and retreatment schedule of these eyes and most ophthalmologists use their clinical experience to decide. Following the disappointing results from the quarterly regimen of the PIER study, which showed us loss of early gained vision during 3-monthly injection period (Regillo et al., 2008), new prospective studies like PrONTO, and SUSTAIN are under way investigating less frequent dosing regimens and preliminary results from these studies suggest that fewer injections (mean: 9.9 injections within 24 months in PrONTO, 5.7 injections within 12 months in SUSTAIN) will most likely result in visual acuity improvements similar to the results from the phase III trials by using a variable dosing regimen with OCT (Fung et al., 2007; Lalwani et al., 2009; Rosenfeld et al.,

Although most of the studies used OCT findings and VA changes to determine the need for additional therapy (Holz et al., 2011), we believe that, some other parameters like, subjective feeling of patients about their vision, presence of hemorrhage associated with the lesion, lesion size, FA staining pattern and are also important for assessment of neovascular AMD activity especially in those undetermined cases. AS is defined to standardize the understanding of findings and definition of active lesion. We are studying on this system since 2002 and have used it in our practice as well as in some of our studies (Ozdek et

It is obvious that ophthalmoscopic appearance of a lesion is very important during interpretation of OCT and FA findings. This is to see new subretinal hemorrhages, exudates and fibrotic scar tissues so that FA and OCT findings can correctly be interpreted. OCT is a very important indicator of neovascular AMD activity and may be assumed as the main determinant for deciding the need for re-treatment in patients with AMD. Recently, there is a tendency to assess the activity of neovascular AMD lesions with only OCT without performing FA after the initial assessment (Brown & Regillo, 2007; Cohen et al., 2007; Rosenfeld et al., 2006b; Salinas-Alamán et al., 2005). This approach has emerged especially after anti-VEGF treatments of neovascular AMD lesions to avoid from monthly FA. Once the diagnosis of neovascular AMD was established with FA before treatment, OCT was reported to have a sensitivity of 96% for detecting lesion activity and a diagnostic efficiency (proportion of correct results) of 83% (Salinas-Alamán et al., 2005). However, OCT cannot detect other features including blood, lipid, and vascular patterns so effectively. When a subretinal new hemorrhage associated with the lesion appears in an eye with a dry OCT and FA (without any late leakage) most of the retina specialists assume it as an active lesion and treat it. This is the case when activation takes place on a far edge of the subfoveal neovascular AMD lesion. Salinas et al reported that, OCT may be complementary to FA, especially in cases in which FA was inconclusive. They have found that OCT was considered as positive (presence of sub-retinal fluid and/or intraretinal fluid) in 14.2% of the cases in which FA did not show clear leakage. On the other hand, most of the cases with positive OCT findings without any leakage on FA (false positives) had a disciform scar with persistent cystic cavities on OCT (Salinas-Alamán et al., 2005). It can be concluded that if there is no fibrotic scar visible during the fundus examination, the presence of remaining

**4. Discussion**

2006b).

al.,2005; Ozdek et al.,2007).

Cut-off AS

Fig. 5. Pre and post treatment difference in AS of highly active group and less active group. Decrease in AS was significantly more in highly active group (pretreatment AS≥7) (p=0.003).

#### **4. Discussion**

152 Age Related Macular Degeneration – The Recent Advances in Basic Research and Clinical Care

Cut-off AS

highly active group) and in group 2 (with an AS of less than 7, less active group).

Fig. 4. Pretreatment and posttreatment mean AS of eyes in group 1 (with an AS of 7 or more,

Cut-off AS

Fig. 5. Pre and post treatment difference in AS of highly active group and less active group. Decrease in AS was significantly more in highly active group (pretreatment AS≥7) (p=0.003).

Pretreatment AS >=7 Pretreatment AS <7

Pretreatment AS >=7 Pretreatment AS <7

Pretreatment AS

Posttreatment AS

Mean Activity Score +/- 2 SE

Difference in AS (Pretreatment - Posttreatment)

9

8

7

6

5

4

3

2

8

6

4

2

0

Neovascular AMD activity is an important factor to determine if it should be treated or not. It is important not to over-treat these eyes to avoid from injection and drug related complications as well as high cost of the treatment. There is no standard protocol for the treatment and retreatment schedule of these eyes and most ophthalmologists use their clinical experience to decide. Following the disappointing results from the quarterly regimen of the PIER study, which showed us loss of early gained vision during 3-monthly injection period (Regillo et al., 2008), new prospective studies like PrONTO, and SUSTAIN are under way investigating less frequent dosing regimens and preliminary results from these studies suggest that fewer injections (mean: 9.9 injections within 24 months in PrONTO, 5.7 injections within 12 months in SUSTAIN) will most likely result in visual acuity improvements similar to the results from the phase III trials by using a variable dosing regimen with OCT (Fung et al., 2007; Lalwani et al., 2009; Rosenfeld et al., 2006b).

Although most of the studies used OCT findings and VA changes to determine the need for additional therapy (Holz et al., 2011), we believe that, some other parameters like, subjective feeling of patients about their vision, presence of hemorrhage associated with the lesion, lesion size, FA staining pattern and are also important for assessment of neovascular AMD activity especially in those undetermined cases. AS is defined to standardize the understanding of findings and definition of active lesion. We are studying on this system since 2002 and have used it in our practice as well as in some of our studies (Ozdek et al.,2005; Ozdek et al.,2007).

It is obvious that ophthalmoscopic appearance of a lesion is very important during interpretation of OCT and FA findings. This is to see new subretinal hemorrhages, exudates and fibrotic scar tissues so that FA and OCT findings can correctly be interpreted. OCT is a very important indicator of neovascular AMD activity and may be assumed as the main determinant for deciding the need for re-treatment in patients with AMD. Recently, there is a tendency to assess the activity of neovascular AMD lesions with only OCT without performing FA after the initial assessment (Brown & Regillo, 2007; Cohen et al., 2007; Rosenfeld et al., 2006b; Salinas-Alamán et al., 2005). This approach has emerged especially after anti-VEGF treatments of neovascular AMD lesions to avoid from monthly FA. Once the diagnosis of neovascular AMD was established with FA before treatment, OCT was reported to have a sensitivity of 96% for detecting lesion activity and a diagnostic efficiency (proportion of correct results) of 83% (Salinas-Alamán et al., 2005). However, OCT cannot detect other features including blood, lipid, and vascular patterns so effectively. When a subretinal new hemorrhage associated with the lesion appears in an eye with a dry OCT and FA (without any late leakage) most of the retina specialists assume it as an active lesion and treat it. This is the case when activation takes place on a far edge of the subfoveal neovascular AMD lesion. Salinas et al reported that, OCT may be complementary to FA, especially in cases in which FA was inconclusive. They have found that OCT was considered as positive (presence of sub-retinal fluid and/or intraretinal fluid) in 14.2% of the cases in which FA did not show clear leakage. On the other hand, most of the cases with positive OCT findings without any leakage on FA (false positives) had a disciform scar with persistent cystic cavities on OCT (Salinas-Alamán et al., 2005). It can be concluded that if there is no fibrotic scar visible during the fundus examination, the presence of remaining

Re-Treatment Strategies for Neovascular AMD: When to Treat? When to Stop? 155

Vision is not only the central VA and it has many other components like scotomas in visual field, contrast sensitivity, color vision etc. So snellen or ETDRS visual acuity measurement may not be enough to assess vision especially in macular diseases. The simplest measure may be to ask the patient his feelings about his vision; if it is the same, decreased or increased. The subjective change in vision may also give important clues about the effect of treatment. However, it is highly dependent on the patients' personality and on the eye (in the better eye or in the worse eye). Patient may feel always worse if he is pessimistic and depressive or vice versa. Patient may feel the changes more precisely if the problem is in the better eye, on the other hand, may not feel the significant changes if the disease is in the worse eye. To overcome such shortcomings of subjective assessment of vision, more objective measures for the assessment of the other components of the central vision may be used. VFQ25 may be an option but takes a long time for these cases and is not so practical. Unver et al have developed a new tool for the automated assessment of functional central vision called central field acuity perimetry to solve such problems (Unver et al., 2009). However there is no clinical study with central field acuity perimetry for this purpose up till now. Microperimetry and functional magnetic resonance imaging are other new tools to measure objective measure of topographic visual function (Baseler et al., 2011; Uppal et al., 2011). On the other hand, deterioration of vision is not always an indication of lesion activity itself. Progression of the dry component of the disease (atrophic changes), fibrosis and cicatrisation of the lesion during healing period following treatment may also cause deterioration of vision. Vision cannot be a sole criterion (just like other parameters) but may add to other factors indicating

Change in lesion area is another important determinant of the activity of the lesion. It is not seldom to see a central inactive lesion without any fluid in OCT or any change in objective measured VA may enlarge with a pseudo-pod like extension from one side indicating an active lesion. They usually feel this difference as a subjective worsening of the vision. On the other side, the lesion area may become smaller after treatment indicating a decreased activity of the lesion. This is also an important complementary parameter for assessment of lesion activity and the response to treatment that needs to be taken into account during

The major problem that we faced during the assessment of the reliability of this scoring system was the absence of a gold standard to define an active lesion which can be used for comparison. Rosenfeld et al were the first to define some criteria to identify an active lesion which needs retreatment with anti-VEGF agents in PrONTO study (Ozdek et al., 2005; Rosenfeld et al., 2006b). However, these criteria were not tested for reliability or sensitivity. Our scoring system has some differences from the criteria used in PrONTO study. Firstly, we used a 10% change in CFT in OCT to be significant instead of 100 micron increase for all cases. Sometimes only 30 microns of increase in CFT may be an important change (especially in minimally edematous fovea) on the other hand, even 100 microns of increase in OCT may be meaningless (especially in highly edematous/elevated fovea). Secondly, we have added change in size of the lesion as another criterion. Thirdly, we used subjective changes in vision as another criterion to decide on retreatments. This is because most of the patients feel some very early changes in lesion activity before any change become apparent

lesion activity.

assessment especially in those gray cases.

fluid on the OCT scan may indicate residual lesion activity. It is also valid to assume that a hyperreflective structure on OCT could be misinterpreted without a fundus examination. Therefore, we believe that OCT, FA, and a fundus examination are complementary examinations that should be interpreted together in those undetermined cases.

Although we used FA as a parameter in AS, we do not mean to say that we have to perform FA at every visit. Actually, we need to score the lesion only if it is not so clear that the lesion is active or not what we call as "undetermined cases"(Figure 6) . In other words, if we are not sure that a patient should be retreated or not, we can apply to the AS just to bring all the parameters together. If we still do not want to perform a FA, we can add only 1 point for FA which is neutral for activity scoring for FA.

Fig. 6. 85 year old woman with a neovascular AMD on the left eye received four doses of intravitreal bevacizumab. On the last visit she had lost 5 letters with a subjective visual impairment. A, early phase of the angiogram. B, late phase of the angiogram. C, fundus photograph. D, OCT image of fovea. This would be an undetermined case without FA. Although the OCT has no sign of active lesion, there are late leakage in FA and objective and subjective visual loss. According to table 1 the patient has an activity score of 8 and assessed as an active lesion.

Change in VA is another very important determinant factor in assessment of treatment effect on neovascular AMD. Usually worsening of VA is a sign of bad response to the treatment and, a stable or increased VA is supposed as a favorable treatment response. It is possible to see patients with a dry OCT and silent ophthalmoscopy without any hemorrhage having a decreased VA both objectively and subjectively. Those patients may have a late leakage in FA indicating activity and treatment need or that VA decrease may be a sign of progression of dry component of AMD.

fluid on the OCT scan may indicate residual lesion activity. It is also valid to assume that a hyperreflective structure on OCT could be misinterpreted without a fundus examination. Therefore, we believe that OCT, FA, and a fundus examination are complementary

Although we used FA as a parameter in AS, we do not mean to say that we have to perform FA at every visit. Actually, we need to score the lesion only if it is not so clear that the lesion is active or not what we call as "undetermined cases"(Figure 6) . In other words, if we are not sure that a patient should be retreated or not, we can apply to the AS just to bring all the parameters together. If we still do not want to perform a FA, we can add only 1 point for FA

Fig. 6. 85 year old woman with a neovascular AMD on the left eye received four doses of intravitreal bevacizumab. On the last visit she had lost 5 letters with a subjective visual impairment. A, early phase of the angiogram. B, late phase of the angiogram. C, fundus photograph. D, OCT image of fovea. This would be an undetermined case without FA. Although the OCT has no sign of active lesion, there are late leakage in FA and objective and subjective visual loss. According to table 1 the patient has an activity score of 8 and assessed

Change in VA is another very important determinant factor in assessment of treatment effect on neovascular AMD. Usually worsening of VA is a sign of bad response to the treatment and, a stable or increased VA is supposed as a favorable treatment response. It is possible to see patients with a dry OCT and silent ophthalmoscopy without any hemorrhage having a decreased VA both objectively and subjectively. Those patients may have a late leakage in FA indicating activity and treatment need or that VA decrease may be a sign of

examinations that should be interpreted together in those undetermined cases.

which is neutral for activity scoring for FA.

as an active lesion.

progression of dry component of AMD.

Vision is not only the central VA and it has many other components like scotomas in visual field, contrast sensitivity, color vision etc. So snellen or ETDRS visual acuity measurement may not be enough to assess vision especially in macular diseases. The simplest measure may be to ask the patient his feelings about his vision; if it is the same, decreased or increased. The subjective change in vision may also give important clues about the effect of treatment. However, it is highly dependent on the patients' personality and on the eye (in the better eye or in the worse eye). Patient may feel always worse if he is pessimistic and depressive or vice versa. Patient may feel the changes more precisely if the problem is in the better eye, on the other hand, may not feel the significant changes if the disease is in the worse eye. To overcome such shortcomings of subjective assessment of vision, more objective measures for the assessment of the other components of the central vision may be used. VFQ25 may be an option but takes a long time for these cases and is not so practical. Unver et al have developed a new tool for the automated assessment of functional central vision called central field acuity perimetry to solve such problems (Unver et al., 2009). However there is no clinical study with central field acuity perimetry for this purpose up till now. Microperimetry and functional magnetic resonance imaging are other new tools to measure objective measure of topographic visual function (Baseler et al., 2011; Uppal et al., 2011). On the other hand, deterioration of vision is not always an indication of lesion activity itself. Progression of the dry component of the disease (atrophic changes), fibrosis and cicatrisation of the lesion during healing period following treatment may also cause deterioration of vision. Vision cannot be a sole criterion (just like other parameters) but may add to other factors indicating lesion activity.

Change in lesion area is another important determinant of the activity of the lesion. It is not seldom to see a central inactive lesion without any fluid in OCT or any change in objective measured VA may enlarge with a pseudo-pod like extension from one side indicating an active lesion. They usually feel this difference as a subjective worsening of the vision. On the other side, the lesion area may become smaller after treatment indicating a decreased activity of the lesion. This is also an important complementary parameter for assessment of lesion activity and the response to treatment that needs to be taken into account during assessment especially in those gray cases.

The major problem that we faced during the assessment of the reliability of this scoring system was the absence of a gold standard to define an active lesion which can be used for comparison. Rosenfeld et al were the first to define some criteria to identify an active lesion which needs retreatment with anti-VEGF agents in PrONTO study (Ozdek et al., 2005; Rosenfeld et al., 2006b). However, these criteria were not tested for reliability or sensitivity. Our scoring system has some differences from the criteria used in PrONTO study. Firstly, we used a 10% change in CFT in OCT to be significant instead of 100 micron increase for all cases. Sometimes only 30 microns of increase in CFT may be an important change (especially in minimally edematous fovea) on the other hand, even 100 microns of increase in OCT may be meaningless (especially in highly edematous/elevated fovea). Secondly, we have added change in size of the lesion as another criterion. Thirdly, we used subjective changes in vision as another criterion to decide on retreatments. This is because most of the patients feel some very early changes in lesion activity before any change become apparent

Re-Treatment Strategies for Neovascular AMD: When to Treat? When to Stop? 157

individual recurrence intervals with a couple of years of experience with PRN regimen and some lesions do not obey any rule of periodical recurrence in long term. The results of these approaches need to be proven with further randomized controlled studies to be

Baseler HA, Gouws A, Crossland MD, Leung C, Tufail A, Rubin GS & Morland AB, (2011).

Brown DM & Regillo CD, (2007). Anti-VEGF agents in the treatment of neovascular age-

Brown DM & Regillo CD, (2007). Anti-VEGF agents in the treatment of neovascular age-

Brown DM, Michels M, Kaiser PK, Heier JS, Sy JP & Ianchulev T, ANCHOR Study Group,

*Ophthalmology.* Vol.116, No.1, (January 2009), pp.57-65.e5, ISSN 0161-6420 Chapman JA & Beckey C, (2006). Pegaptanib: a novel approach to ocular

Cohen SY, Korobelnik JF, Tadayoni R, Coscas G, Creuzot-Garcher C, Devin F, Gaudric A,

Eter N & Spaide RF, (2005). Comparison of fluorescein angiography and optical

Ferris FL III, Fine SL & Hyman L, (1984). Age-related macular degeneration and blindness

Friedman DS, O'Colmain BJ, Muñoz B, Tomany SC, McCarty C, de Jong PT, Nemesure B,

Fung AE, Lalwani GA, Rosenfeld PJ, Dubovy SR, Michels S, Feuer WJ, Puliafito CA, Davis

<http://www.ncbi.nlm.nih.gov/pubmed/21705938>

Objective Visual Assessment of Antiangiogenic Treatment for Wet Age-Related Macular Degeneration. In: *Optom Vis Sci.*, e-pub, June 2011, Available from:

related macular degeneration: applying clinical trial results to the treatment of everyday patients. *Am J Ophthalmol.*, Vol.144, No.4, (October 2007), pp.627-37, ISSN

related macular degeneration: applying clinical trial results to the treatment of everyday patients. *Am J Ophthalmol*., Vol.144, No.4, (October 2007), pp.627–37, ISSN

(2009). Ranibizumab versus verteporfin photodynamic therapy for neovascular age-related macular degeneration: Two-year results of the ANCHOR study.

neovascularization. *Ann Pharmacother.,* Vol.40, No.7-8, (July-August 2006), pp.1322–

Mauget-Faysse M, Sahel JA, Souied E, Weber M & Soubrane G, (2007). Monitoring anti-VEGF drugs for treatment of exudative AMD. *J Fr Ophtalmol*, Vol.30, No.4,

coherence tomography for patients with choroidal neovascularization after photodynamic therapy. *Retina*, Vol.25, No.6, (September 2005), pp.691-6, ISSN 0275-

due to neovascular maculopathy. *Arch Ophthalmol.*, Vol.102, No. 11, (November

Mitchell P & Kempen J, Eye Diseases Prevalence Research Group, (2004). Prevalence of agerelated macular degeneration in the United States. *Arch Ophthalmol.,* Vol.122, No.4, (April 2004), pp.564 –72, ISSN 0003-9950

JL, Flynn HW Jr & Esquiabro M, (2007). An optical coherence tomography-guided,

conclusive.

**6. References**

0002-9394

0002-9394

6, ISSN 1060-0280

004X

(April 2007), pp.330-4, ISSN 0181-5512

1984), pp.1640–2, ISSN 0003-9950

Friedman et al., 2004

in FA, OCT or ETDRS visual acuity testing. We strongly believe that this should be taken into account during assessment of lesion activity.

We would like to emphasize on the unequal distribution of points between different parameters of the AS. We have purposefully given higher scores for hemorrhage (3 points), OCT (3 points) and VA (2+2 points) which are more powerful indicators of the lesion activity than the FA and lesion size.

When we take all of these parameters into account and score it, we observed that pretreatment mean AS was 7.4 which decreased significantly to 4.2 after treatment. Which means that AS really indicates the activity of the lesion. We also observed that a lesion with a higher AS is more likely to give more dramatic response to the anti-VEGF treatment with a more significant decrease in AS (Figure 4).

Transferring these data to the clinical applications, it seems logical to treat lesions with an AS of 7 or more with anti-VEGF therapy. The high sensitivity (86%) and positive predictive values (90%) of the AS strongly suggest retreatment of lesions with an AS of 7 or more. However the lower sensitivity and negative predictive values of AS weakly supports observation of the ones with lower AS without treatment. The lower rates are most possibly because of the lower number of the eyes with less AS who had still been treated with anti-VEGF. When the number of such eyes had been equal to the treated eyes with higher AS, the specificity and negative predictive values of AS might have been higher which would make the AS a more reliable measure.

In addition to routine clinical practice, AS may be used as a standard way of assessment of lesion activity especially in clinical studies for the statistical comparison of the results. AS may be a valuable tool to see the picture (both the lesion and the response to the treatment) as a whole.

#### **5. Conclusions**

In conclusion, assessment of the lesion activity is important for PRN treatment approaches and AS seems to be a standardized measure to assess the activity of the lesion at the beginning as well as the treatment effect after anti-VEGF therapy. It may be modified with use of some other tools like central field acuity perimetry to be more objective. A lesion with an AS of 7 or more seems to be an active lesion which needs treatment and it most possibly will give a favorable response to anti-VEGF treatment as a decrease in activity. However, the sensitivity and specificity of AS needs to be tested with further studies with larger number of patients to be conclusive. Additionally scoring of the lesion activity quantifies the lesion activity allowing for statistical comparisons between different treatment methods in clinical studies.

Individualized approaches, on the other side, may be a good option in suitable cases. Reinjections shortly prior to a recurrence may avoid further growth of the CNV lesion size, protecting the neural retina from additional damage and improve the long-term prognosis. This may be a better option than PRN approaches preventing recurrences other than treating the recurrence. However, this approach requires the ability to determine individual recurrence intervals with a couple of years of experience with PRN regimen and some lesions do not obey any rule of periodical recurrence in long term. The results of these approaches need to be proven with further randomized controlled studies to be conclusive.

#### **6. References**

156 Age Related Macular Degeneration – The Recent Advances in Basic Research and Clinical Care

in FA, OCT or ETDRS visual acuity testing. We strongly believe that this should be taken

We would like to emphasize on the unequal distribution of points between different parameters of the AS. We have purposefully given higher scores for hemorrhage (3 points), OCT (3 points) and VA (2+2 points) which are more powerful indicators of the lesion

When we take all of these parameters into account and score it, we observed that pretreatment mean AS was 7.4 which decreased significantly to 4.2 after treatment. Which means that AS really indicates the activity of the lesion. We also observed that a lesion with a higher AS is more likely to give more dramatic response to the anti-VEGF treatment with a

Transferring these data to the clinical applications, it seems logical to treat lesions with an AS of 7 or more with anti-VEGF therapy. The high sensitivity (86%) and positive predictive values (90%) of the AS strongly suggest retreatment of lesions with an AS of 7 or more. However the lower sensitivity and negative predictive values of AS weakly supports observation of the ones with lower AS without treatment. The lower rates are most possibly because of the lower number of the eyes with less AS who had still been treated with anti-VEGF. When the number of such eyes had been equal to the treated eyes with higher AS, the specificity and negative predictive values of AS might have been higher which would make

In addition to routine clinical practice, AS may be used as a standard way of assessment of lesion activity especially in clinical studies for the statistical comparison of the results. AS may be a valuable tool to see the picture (both the lesion and the response to the treatment)

In conclusion, assessment of the lesion activity is important for PRN treatment approaches and AS seems to be a standardized measure to assess the activity of the lesion at the beginning as well as the treatment effect after anti-VEGF therapy. It may be modified with use of some other tools like central field acuity perimetry to be more objective. A lesion with an AS of 7 or more seems to be an active lesion which needs treatment and it most possibly will give a favorable response to anti-VEGF treatment as a decrease in activity. However, the sensitivity and specificity of AS needs to be tested with further studies with larger number of patients to be conclusive. Additionally scoring of the lesion activity quantifies the lesion activity allowing for statistical comparisons between different treatment methods in

Individualized approaches, on the other side, may be a good option in suitable cases. Reinjections shortly prior to a recurrence may avoid further growth of the CNV lesion size, protecting the neural retina from additional damage and improve the long-term prognosis. This may be a better option than PRN approaches preventing recurrences other than treating the recurrence. However, this approach requires the ability to determine

into account during assessment of lesion activity.

activity than the FA and lesion size.

more significant decrease in AS (Figure 4).

the AS a more reliable measure.

as a whole.

**5. Conclusions**

clinical studies.

variable-dosing regimen with intravitreal ranibizumab (Lucentis) for neovascular age-related macular degeneration. *Am J Ophthalmol.* Vol.143, No.4, (April 2007), pp.566–583, ISSN 0002-9394

Re-Treatment Strategies for Neovascular AMD: When to Treat? When to Stop? 159

Rosenfeld PJ, Brown DM, Heier JS, Boyer DS, Kaiser PK, Chung CY & Kim RY, MARINA

Rosenfeld PJ, Moshfeghi AA & Puliafito CA, (2005). Optical coherence tomography findings

Rosenfeld PJ, Rich RM & Lalwani GA, (2006). Ranibizumab: Phase III clinical trial results.

Salinas-Alamán A, García-Layana A, Maldonado MJ, Sainz-Gómez C & Alvárez-Vidal A,

Schmidt-Erfurth UM, Richard G, Augustin A, Aylward WG, Bandello F, Corcòstegui B,

Spaide R. Ranibizumab according to need: a treatment for age-related macular

Şekeryapan B, Özdek Ş, Özmen MC, Gürelik G & Hasanreisoğlu B, (2011). Yaşa Bağl

Unver YB, Yavuz GA, Bekiroğlu N, Presti P, Li W & Sinclair SH, (2009). Relationships

Uppal G, Feely M, Crossland M, Membrey L, Lee J, da Cruz L & Rubin

van Velthoven ME, de Smet MD, Schlingemann RO, Magnani M & Verbraak

*Retina-Vitreus,* Vol.19, No.2, (June 2011), pp.97-102, ISSN 1300-1256

pp.1419-31, ISSN 0028-4793

2005), pp.331–5, ISSN 1542-8877

pp.23-8, ISSN 0002-9394

1549

3907

9394

222X

1552-5783

832X

Study Group, (2006). Ranibizumab for neovascular age-related macular degeneration. *New England Journal of Medicine,* Vol.355, No.14, (October 2006),

after an intravitreal injection of bevacizumab (Avastin) for neovascular age-related macular degeneration. *Ophthalmic Surg Lasers Imaging*., Vol.36, No.4, (July-August

*Ophthalmol Clin North Am.,* Vol.19, No.3, (September 2006), pp.361-72, ISSN 0896-

(2005). Using optical coherence tomography to monitor photodynamic therapy in age related macular degeneration. *Am J Ophthalmol.,* Vol.140, No.1, (July 2005),

Cunha-Vaz J, Gaudric A, Leys A, Schlingemann RO; European Society for Retina Specialists' Guidelines Committee (EURETINA), (2007). Guidance for the treatment of neovascular age-related macular degeneration. *Acta Ophthalmologica Scandinavica,* Vol.85, No.5, (August, 2007), pp.486-94, ISSN 1395-

degeneration. *Am J Ophthalmol.* Vol.143, No.4, (April 2007), pp.679–80, ISSN 0002-

Maküla Dejenerasyonuna Bağl Koroidal Neovaskülarizasyon Tedavisinde Tek Başna Bevacizumab veya Fotodinamik Tedavi ile Kombinasyon: 12 Ay Sonuçlar.

between clinical measures of visual function and anatomic changes associated with bevacizumab treatment for choroidal neovascularization in age-related macular degeneration. *Eye,* Vol.23, No.2, (February 2009), pp.453-60, ISSN 0950-

GS, (2011). Assessment of Reading Behaviour with an Infrared Eyetracker after 360 Degree Macular Translocation for Age Related Macular Degeneration. *Invest Ophthalmol Vis Sci.*, Vol.52, No.9, (August 2011), pp.6486-96, ISSN

FD, (2006). Added value of OCT in evaluating the presence of leakage in patients with age-related macular degeneration treated with PDT. *Graefes Arch Clin Exp Ophthalmol.*, Vol.244, No.9, (September 2006), pp.1119-23, ISSN 0721-

Gupta OP, Shienbaum G, Patel AH, Fecarotta C, Kaiser RS & Regillo CD, (2010). A treat and

Holz FG, Amoaku W, Donate J, Guymer RH, Kellner U, Schlingemann RO, Weichselberger

Hörster R, Ristau T, Sadda SR & Liakopoulos S, (2011). Individual recurrence intervals after

Klein R, Klein BE & Linton KL, (1992). Prevalence of age-related maculopathy: the Beaver

Krebs I, Ansari-Shahrezaei S, Goll A & Binder S, (2008). Activity of neovascular lesions

Lalwani GA, Rosenfeld PJ, Fung AE, Dubovy SR, Michels S, Feuer W, Davis JL,

Oubraham H, Cohen SY, Samimi S, Marotte D, Bouzaher I, Bonicel P, Fajnkuchen

Ozdek S, Bozan E, Gurelik G & Hasanreisoglu B, (2007). Transpupillary thermotherapy

*Can J Ophthalmol*., Vol.42, No.1, (February 2007), pp.95-100, ISSN 0008-4182 Ozdek S, Hondur A, Gurelik G & Hasanreisoglu B, (2005). Transpupillary t

Regillo CD, Brown DM, Abraham P, Yue H, Ianchulev T, Schneider S & Shams N (2008).

No.2, (February 2008), pp.239-48, ISSN 0002-9394

*Ophthalmol.,* Vol.249, No.5, (May 2011), pp.645-52, ISSN 0721-832X

pp.566–583, ISSN 0002-9394

2008), pp.811-5, ISSN 0721-832X

0161-6420

6420

0002-9394

004X

ISSN 0165-5701

(November 2010), pp.2134-40, ISSN 0161-6420

variable-dosing regimen with intravitreal ranibizumab (Lucentis) for neovascular age-related macular degeneration. *Am J Ophthalmol.* Vol.143, No.4, (April 2007),

extend regimen using ranibizumab for neovascular age-related macular degeneration clinical and economic impact. *Ophthalmology*, Vol.117, No.11,

A & Staurenghi G, SUSTAIN Study Group, (2011). Safety and efficacy of a flexible dosing regimen of ranibizumab in neovascular age-related macular degeneration: the SUSTAIN study. *Ophthalmology,* Vol.118, No.4, (April 2011), pp.663-71, ISSN

anti-VEGF therapy for age-related macular degeneration. *Graefes Arch Clin Exp*

Dam Eye Study. *Ophthalmology*, Vol.99, No.6, (June 1992), pp.933–43, ISSN 0161-

treated with bevacizumab: comparison between optical coherence tomography and fluorescein angiography. *Graefes Arch Clin Exp Ophthalmol.,* Vol.246, No.6, (June

Flynn HW Jr & Esquiabro M, (2009). A variable-dosing regimen with intravitreal ranibizumab for neovascular age-related macular degeneration: year 2 of the PrONTO Study. *Am J Ophthalmol.*, Vol.148, No.1, (July 2009), pp.43-58.e1, ISSN

F & Tadayoni R, (2011). Inject and extend dosing versus dosing as needed: a comparative retrospective study of ranibizumab in exudative age-related macular degeneration. *Retina*, Vol.31, No.1, (January 2011), pp.26-30, ISSN 0275-

for the treatment of choroidal neovascularization secondary to angioid streaks.

hermotherapy for myopic choroidal neovascularization: 1-year follow-up: TTT for myopic CNV. *Int Ophthalmol.,* Vol.26, No.4-5, (August-October 2005), pp.127-33,

Randomized, double-masked, sham-controlled trial of ranibizumab for neovascular age-related macular degeneration: PIER Study year 1. *Am J Ophthalmol.*, Vol.145,

Web JA. (January 2008). Genentech decision expands access to bevacizumab. In: *Ophthalmology Times,* 2011, Available from: <http://ophthalmologytimes.modernmedicine.com/ophthalmologytimes/issue/is sueDetail.jsp?id=13920>.

**9**

*Spain*

**Combined Therapies to Treat**

*Fundacion Oftalmologica Mediterraneo, Valencia*

**CNV in AMD: PDT + Anti-VEGF**

Jorge Mataix, M. Carmen Desco, Elena Palacios and Amparo Navea

Age-related macular degeneration (AMD) causes a high incidence of morbility in the elderly. The dry forms of the disease are the most usual, but wet forms (15% of the total of cases) are responsible for 80% of AMD-related cases of severe vision loss. Age-related macular degeneration is essentially a choroidal/retinal pigment epithelium (RPE) disease which affects the overlying neurosensory retina. Formation of choroidal neovessels that penetrate the subretinal space is the main cause of vision loss. Knowing what role the vascular endothelial growth factor (VEGF) plays in angiogenesis of the formation of these neovessels is a determining factor. Ferrara's studies describe the four main biological

Since the formation of choroidal neovascularization (CNV) is a determining factor in vision loss in wet AMD, it is reasonable to expect a reduction in the risk of vision loss by inhibiting new vessel formation and preventing their growth. The efficacy of antiangiogenesis agents for this purpose has provided proof of the concept of therapy targeted at a specific molecular step in the process, namely the inhibition of VEGF (Gragouas et al. 2004). Therefore the appearance of antibodies against VEGF (anti-VEGF) brought about a considerable advance in the treatment of exudative forms of AMD. The most important effects are **regression** of existing vessels, **normalization** of surviving vessels, and **inhibition**

Antiangiogenesis agents have proved to be beneficial but are often administered late in the process when the aim of the treatment is to salvage vision rather than to prevent vision loss. One obstacle in developing a single approach to treatment stems from the possibility that AMD is the product of multiple pathologic processes. A more exciting goal is halting the process at a subclinical stage or preventing the disease in patients identified as being at risk for vision loss. Progress in isolating multiple processes responsible for disease progression is

**1. Introduction**

of vessel growth.

functions in VEGF agents (Ferrara & Gerber, 2001):

2. Growth and proliferation of vascular endothelial cells

creating new opportunities for combination therapies.

4. Survival of immature endothelial cells by preventing apoptosis

1. Increase in vascular permeability

3. Migration of vascular endothelial cells

### **Combined Therapies to Treat CNV in AMD: PDT + Anti-VEGF**

Jorge Mataix, M. Carmen Desco, Elena Palacios and Amparo Navea *Fundacion Oftalmologica Mediterraneo, Valencia Spain*

#### **1. Introduction**

160 Age Related Macular Degeneration – The Recent Advances in Basic Research and Clinical Care

Web JA. (January 2008). Genentech decision expands access to bevacizumab. In:

<http://ophthalmologytimes.modernmedicine.com/ophthalmologytimes/issue/is

*Ophthalmology Times,* 2011, Available from:

sueDetail.jsp?id=13920>.

Age-related macular degeneration (AMD) causes a high incidence of morbility in the elderly. The dry forms of the disease are the most usual, but wet forms (15% of the total of cases) are responsible for 80% of AMD-related cases of severe vision loss. Age-related macular degeneration is essentially a choroidal/retinal pigment epithelium (RPE) disease which affects the overlying neurosensory retina. Formation of choroidal neovessels that penetrate the subretinal space is the main cause of vision loss. Knowing what role the vascular endothelial growth factor (VEGF) plays in angiogenesis of the formation of these neovessels is a determining factor. Ferrara's studies describe the four main biological functions in VEGF agents (Ferrara & Gerber, 2001):

Since the formation of choroidal neovascularization (CNV) is a determining factor in vision loss in wet AMD, it is reasonable to expect a reduction in the risk of vision loss by inhibiting new vessel formation and preventing their growth. The efficacy of antiangiogenesis agents for this purpose has provided proof of the concept of therapy targeted at a specific molecular step in the process, namely the inhibition of VEGF (Gragouas et al. 2004). Therefore the appearance of antibodies against VEGF (anti-VEGF) brought about a considerable advance in the treatment of exudative forms of AMD. The most important effects are **regression** of existing vessels, **normalization** of surviving vessels, and **inhibition** of vessel growth.

Antiangiogenesis agents have proved to be beneficial but are often administered late in the process when the aim of the treatment is to salvage vision rather than to prevent vision loss. One obstacle in developing a single approach to treatment stems from the possibility that AMD is the product of multiple pathologic processes. A more exciting goal is halting the process at a subclinical stage or preventing the disease in patients identified as being at risk for vision loss. Progress in isolating multiple processes responsible for disease progression is creating new opportunities for combination therapies.

Combined Therapies to Treat CNV in AMD: PDT + Anti-VEGF 163

Fig. 2. Phases in angiogenesis in which the formation of a neovessel guided by the

which, in the long term, often plays a determining role in vision loss.

Blocking the extravascular component, like inhibiting subretinal fibrosis, can considerably reduce the morbility of the disease. Biological therapies mediated by cytokines, such as the tumor necrosis factor, ionizing radiation which does not only act on the vascular component but also on the extravascular component, corticosteroid drugs combined with anti-VEGF can improve the therapeutic response, inhibiting the development of the extracellular matrix

Currently, the most relevant therapy available is VEGF inhibition. Possibly, greater success could be achieved if other key factors in pathogenesis were also inhibited. It would be more advantageous if angiogenesis, scarring, and inflammation were targeted simultaneously. Combination approaches may not only increase overall efficacy but also reduce the potential for side effects by allowing relatively low doses to yield a greater level of efficacy than

The appearance of anti-VEGF is a revolutionary treatment in wet AMD as, for the first time, the progression of the disease can be stopped. Nevertheless, it cannot restore vision and there are still many cases that progress in spite of repeated treatment with anti-VEGF. Listed below are several limitations of anti-VEGF that make the quest for other therapies, or a

As described above, one of the functions of VEGF is favoring the survival of endothelial cells, but this function is just restricted to immature vessels in which angiogenesis

extracellular matrix is shown (Genentech image).

**3. Limitations of anti-VEGF in CNV treatment**

**3.1 Anti-VEGF agents do not affect mature vessels**

higher doses of a single agent.

combination of therapies, necessary.

#### **2. Composition of neovessels**

Histopathologic examination of CNV shows granulation-like tissue, with the invasion of not only blood vessels, but also inflammatory and mesenchymal cells embedded in a loosely formed extracellular matrix. Although the majority of damage attributed to CNV is due to neovessel bleeding or leakage, there are other components and factors associated with CNV that influence the visual prognosis decisively.

A two-component model of CNV has been developed to offer a conceptual framework to structure combination treatments. One is the *vascular component*, which is composed of vascular endothelial cells and associated pericytes. The other is the *nonvascular component* which is made up of the remaining cells, such as the inflammatory cells, glial cells, myofibroblasts, and fibrocytes (Spaide, 2006a, 2009). Inhibiting one has the potential to inhibit, at least partially, the other due to mutual interactions between the two components and each component can potentially cause damage. Inhibiting either one would seem to offer some hope in slowing down or arresting the process, but inhibition of both would intuitively lead to the best theoretical outcome.

Blocking the vascular component is achieved mainly by administering anti-VEGF agents, although in advanced lesions with mature neovessels covered by pericytes, anti-VEGF on their own cannot make these neovessels regress. In these cases, a combination of other therapies has to be resorted to which act by means of selective mechanisms, such as blocking the platelet-derived growth factor (PDGF) to target the pericytes, or a non-selective attack mechanism, such as ionizing radiation which is explained further on (Jain RK, 2005) in this chapter.

Fig. 1. CNV components: vascular and nonvascular components

Histopathologic examination of CNV shows granulation-like tissue, with the invasion of not only blood vessels, but also inflammatory and mesenchymal cells embedded in a loosely formed extracellular matrix. Although the majority of damage attributed to CNV is due to neovessel bleeding or leakage, there are other components and factors associated with CNV

A two-component model of CNV has been developed to offer a conceptual framework to structure combination treatments. One is the *vascular component*, which is composed of vascular endothelial cells and associated pericytes. The other is the *nonvascular component* which is made up of the remaining cells, such as the inflammatory cells, glial cells, myofibroblasts, and fibrocytes (Spaide, 2006a, 2009). Inhibiting one has the potential to inhibit, at least partially, the other due to mutual interactions between the two components and each component can potentially cause damage. Inhibiting either one would seem to offer some hope in slowing down or arresting the process, but inhibition of both would

Blocking the vascular component is achieved mainly by administering anti-VEGF agents, although in advanced lesions with mature neovessels covered by pericytes, anti-VEGF on their own cannot make these neovessels regress. In these cases, a combination of other therapies has to be resorted to which act by means of selective mechanisms, such as blocking the platelet-derived growth factor (PDGF) to target the pericytes, or a non-selective attack mechanism, such as ionizing radiation which is explained further on (Jain RK, 2005) in this

**2. Composition of neovessels**

that influence the visual prognosis decisively.

intuitively lead to the best theoretical outcome.

Fig. 1. CNV components: vascular and nonvascular components

chapter.

Fig. 2. Phases in angiogenesis in which the formation of a neovessel guided by the extracellular matrix is shown (Genentech image).

Blocking the extravascular component, like inhibiting subretinal fibrosis, can considerably reduce the morbility of the disease. Biological therapies mediated by cytokines, such as the tumor necrosis factor, ionizing radiation which does not only act on the vascular component but also on the extravascular component, corticosteroid drugs combined with anti-VEGF can improve the therapeutic response, inhibiting the development of the extracellular matrix which, in the long term, often plays a determining role in vision loss.

Currently, the most relevant therapy available is VEGF inhibition. Possibly, greater success could be achieved if other key factors in pathogenesis were also inhibited. It would be more advantageous if angiogenesis, scarring, and inflammation were targeted simultaneously. Combination approaches may not only increase overall efficacy but also reduce the potential for side effects by allowing relatively low doses to yield a greater level of efficacy than higher doses of a single agent.

#### **3. Limitations of anti-VEGF in CNV treatment**

The appearance of anti-VEGF is a revolutionary treatment in wet AMD as, for the first time, the progression of the disease can be stopped. Nevertheless, it cannot restore vision and there are still many cases that progress in spite of repeated treatment with anti-VEGF. Listed below are several limitations of anti-VEGF that make the quest for other therapies, or a combination of therapies, necessary.

#### **3.1 Anti-VEGF agents do not affect mature vessels**

As described above, one of the functions of VEGF is favoring the survival of endothelial cells, but this function is just restricted to immature vessels in which angiogenesis

Combined Therapies to Treat CNV in AMD: PDT + Anti-VEGF 165

In this way, the angiogenic factors basically act as survival factors, while antiangiogenic factors act as apoptosis-inducing factors in the context of endothelial expansion, which is an immature endothelium. Thus the balance between the inducing and inhibiting factors determines the destiny of immature vessels, but they do not bear an influence on mature vessels that are in a quiescent state due to the interaction between endothelial cells, pericytes, and the extracellular matrix (Jimenez Cuenca B, 2003). Therefore, if the neovessels are already mature, they will not react to VEGF, nor will they respond to anti-VEGF (Benjamin et. al., 1999). This fact underpins the value of combined therapies like photodynamic therapy (PDT) with verteporfin, which is necessary to destroy the architecture of different mature components of the neovascular

Despite their beneficial clinical effects in AMD, anti-VEGF therapies are ineffective in regressing existing lesions. Endothelial cells and pericytes that form the structure of new vascular tissue typically do not regress with VEGF inhibition alone. This limitation is confirmed by data from the key prospective, randomized clinical trials with Ranibizumab, such as PIER, ANCHOR, and MARINA (Regillo et al., 2008; Brown et al., 2006; Rosenfeld et al., 2006) which did not produce any significant evidence of neovascular regression despite improvement in visual acuity. There are no changes from baseline in the CNV area. This lack of regression is also consistent with experimental models in which monotherapy with anti-VEGF agents inhibits new vascular formation but has little effect on existing capillaries. Despite the importance of VEGF agents in the cascade of events that stimulates and sustains new vascular formation, VEGF inhibition may have limited effects on existing neovascular tissue once subsequent molecular events are triggered, making inhibition of additional

Recent publications refer to the possible existence of tachyphylaxis after use of intravitreal Bevacizumab. Forooghian and co-workers describe a decrease in the duration of the beneficial effect, and even a lack of response, after a mean of eight intravitreal injections (Forooghian et al., 2009) in six (n = 59) patients with AMD treated with Bevacizumab in

Currently, the existence of tachyphylaxis is under discussion and its mechanism is unknown. This author poses the possibility of an autoimmune mechanism after a patient, suffering from uveitis, presented tachyphylaxis immediately after intravitreal injection. It must be remembered that Bevacizumab, in spite of being a "humanized" antibody for decreasing immunogenicity, could trigger the formation of new anti-Bevacizumab

In addition, it should be considered that always inhibiting the same vascular pathway may potentiate other pathogenic pathways, such as the inflammatory pathway, or that it may increase other cytokines involved in wet AMD. Certainly, a greater inflammatory activity and a proliferation of macrophages in the membranes that were surgically extracted with prior Bevacizumab treatment were observed compared with those extracted without prior

membrane that do not respond to anti-VEGF.

**3.3 Tachyphylaxis**

monotherapy.

intravitreal treatment (Tatar et al., 2009).

**3.2 Anti-VEGF agents do not decrease the CNV size**

molecular steps essential to build on the benefits of anti-VEGF therapies.

antibodies after repeated treatments; this hypothesis has yet to be studied.

necessarily requires the activation of survival pathways to maintain the condition of the vessels (Gerber et al., 1998). Nonetheless, the mechanisms involved in the maturing process of the vessels, such as pericyte coverage and the formation of interaction between endothelial and periendotherlial cells with the basal membrane, free the endothelial cell from the requirement of the survival function of VEGF.

Fig. 3. Composition of a mature blood vessel, made up of endothelial cells, pericyte coverage, and the interactions between them.

Fig. 4. When the factors that inhibit angiogenesis predominate over those that induce it, two things can occur, depending on the context. If the vessel is mature, it will show no response as it is quiescent and is not affected by the effect of the antiangiogenic drugs. However, if the vessels are immature, with no pericyte coverage, the angiogenesis inhibitors will favor apoptosis and the regression of the vessel. When proangiogenic factors predominate the immature vessel survives and stabilizes.

In this way, the angiogenic factors basically act as survival factors, while antiangiogenic factors act as apoptosis-inducing factors in the context of endothelial expansion, which is an immature endothelium. Thus the balance between the inducing and inhibiting factors determines the destiny of immature vessels, but they do not bear an influence on mature vessels that are in a quiescent state due to the interaction between endothelial cells, pericytes, and the extracellular matrix (Jimenez Cuenca B, 2003). Therefore, if the neovessels are already mature, they will not react to VEGF, nor will they respond to anti-VEGF (Benjamin et. al., 1999). This fact underpins the value of combined therapies like photodynamic therapy (PDT) with verteporfin, which is necessary to destroy the architecture of different mature components of the neovascular membrane that do not respond to anti-VEGF.

#### **3.2 Anti-VEGF agents do not decrease the CNV size**

Despite their beneficial clinical effects in AMD, anti-VEGF therapies are ineffective in regressing existing lesions. Endothelial cells and pericytes that form the structure of new vascular tissue typically do not regress with VEGF inhibition alone. This limitation is confirmed by data from the key prospective, randomized clinical trials with Ranibizumab, such as PIER, ANCHOR, and MARINA (Regillo et al., 2008; Brown et al., 2006; Rosenfeld et al., 2006) which did not produce any significant evidence of neovascular regression despite improvement in visual acuity. There are no changes from baseline in the CNV area. This lack of regression is also consistent with experimental models in which monotherapy with anti-VEGF agents inhibits new vascular formation but has little effect on existing capillaries.

Despite the importance of VEGF agents in the cascade of events that stimulates and sustains new vascular formation, VEGF inhibition may have limited effects on existing neovascular tissue once subsequent molecular events are triggered, making inhibition of additional molecular steps essential to build on the benefits of anti-VEGF therapies.

#### **3.3 Tachyphylaxis**

164 Age Related Macular Degeneration – The Recent Advances in Basic Research and Clinical Care

necessarily requires the activation of survival pathways to maintain the condition of the vessels (Gerber et al., 1998). Nonetheless, the mechanisms involved in the maturing process of the vessels, such as pericyte coverage and the formation of interaction between endothelial and periendotherlial cells with the basal membrane, free the endothelial cell

Fig. 3. Composition of a mature blood vessel, made up of endothelial cells, pericyte

Fig. 4. When the factors that inhibit angiogenesis predominate over those that induce it, two things can occur, depending on the context. If the vessel is mature, it will show no response as it is quiescent and is not affected by the effect of the antiangiogenic drugs. However, if the vessels are immature, with no pericyte coverage, the angiogenesis inhibitors will favor apoptosis and the regression of the vessel. When proangiogenic factors predominate the

from the requirement of the survival function of VEGF.

coverage, and the interactions between them.

immature vessel survives and stabilizes.

Recent publications refer to the possible existence of tachyphylaxis after use of intravitreal Bevacizumab. Forooghian and co-workers describe a decrease in the duration of the beneficial effect, and even a lack of response, after a mean of eight intravitreal injections (Forooghian et al., 2009) in six (n = 59) patients with AMD treated with Bevacizumab in monotherapy.

Currently, the existence of tachyphylaxis is under discussion and its mechanism is unknown. This author poses the possibility of an autoimmune mechanism after a patient, suffering from uveitis, presented tachyphylaxis immediately after intravitreal injection. It must be remembered that Bevacizumab, in spite of being a "humanized" antibody for decreasing immunogenicity, could trigger the formation of new anti-Bevacizumab antibodies after repeated treatments; this hypothesis has yet to be studied.

In addition, it should be considered that always inhibiting the same vascular pathway may potentiate other pathogenic pathways, such as the inflammatory pathway, or that it may increase other cytokines involved in wet AMD. Certainly, a greater inflammatory activity and a proliferation of macrophages in the membranes that were surgically extracted with prior Bevacizumab treatment were observed compared with those extracted without prior intravitreal treatment (Tatar et al., 2009).

Combined Therapies to Treat CNV in AMD: PDT + Anti-VEGF 167

In a study in which 82 patients, treated with Ranibizumab monotherapy, were monitored in a follow-up of two to six years, reported that the rate of fibrosis was 50% and the rate of atrophy of the retinal pigment epithelium was 40%; 8% percent had both. The fibrosis may have been caused by ongoing inflammation and by maturation of vascular tissue. Hemorrhage above or below the subretinal pigment epithelium may have played a contributing role. Fibrosis was often observed after several years of antiangiogenesis

These findings reinforce other evidence that fibrosis may be an important additional target to expand or preserve the benefits of Ranibizumab and other VEGF inhibitors in the treatment of AMD. Several strategies are being pursued. These include antagonists of integrin, inhibitors of the mammalian target of rapamycin, vascular disrupting agents, and radiation. Control of atrophy, which is generally observed at an earlier stage of AMD progression than fibrosis, is another potential target for improving outcome. The candidate targets for preventing atrophy include neurotrophic factors, free radical scavengers, and retinol binding competitors.

Even the maximum inhibition of VEGF does not stop vascular growth due to the presence of redundant signaling pathways. Controlling one pathway, the inhibition of neovascularization is relatively modest due to the presence of redundant signaling pathways. The combination of molecules inhibit different parts of the angiogenic process and provide more profound inhibition of neovascularization relative to blocking a single

When one of two inhibitors of angiogenesis was used in experimental studies (Dorrell et al., 2007) complete inhibition of new vessel formation was achieved in a small proportion of animals. In contrast, complete inhibition of neovascularization was observed in more than

Transscleral and intravitreal injections are alternative methods of local delivery. These methods may reduce the risk of systemic absorption, because topical therapy results in a significant amount of the drug draining away from the eye through the nasal lacrimal duct into the gut. Transscleral and intravitreal injections may also increase the percentage of the dose that reaches a posterior target. The efficacy of this approach is well documented with antiangiogenic therapies for AMD, but it is not risk-free for the patient, and moreover, it requires surgical administration, which in many cases can cause saturation of operating rooms and delays to the detriment of the patient. Moreover, as it is a chronic disease, retreatment is often necessary which increases these problems. Association of anti-VEGF with other therapies can be useful in reducing the number of anti-VEGF doses without

Not least important is the potential for unwanted effects on the biologic function controlled by drug targets, such as prolonged suppression of a complex molecule like VEGF, which while being a key factor in causing CNV associated with AMD, also plays an important role

therapy even among responders (Kaiser PK, 2009c).

**3.5 Several pathogenic pathways involved**

proangiogenic signal (Frielander, 2009).

reducing its effectiveness.

as a neuroprotectant in the mature retina.

half of the animals treated with triple combination therapy.

**3.6 Route of administration, number and frequency of doses**

Complement inhibition may be another viable strategy (Heier JS, 2009).

Furthermore a better response to intravitreal corticoids has been observed in patients who stop responding to anti-VEGF intravitreal injections (Schaal et al., 2008). Therefore we pose a future problem regarding the use of anti-VEGF, i.e., how to avoid this occurrence. One of the most appropriate options would be to find the way to reduce the number of intravitreal injections in the treatment of AMD and, to date, the only way is with combined therapies.

#### **3.4 Anti-VEGF agents do not act on fibrosis and atrophy**

Long-term follow-up of patients who participated in the initial studies of anti-VEGF therapies suggests that late visual loss is often caused by processes that seem to be independent of neovascularization, particularly fibrosis and atrophy. Although more effective antiangiogenesis treatments, including combination strategies, for better blockade of new vessel formation are likely to improve outcome, it is appropriate to expand targets to other pathophysiologic processes associated with AMD. It is necessary to incorporate therapies that block fibrosis and inhibit atrophy or other pathophysiologic processes not directly related to neovascularization.

In Ranibizumab trials (Rosenfeld et al., 2006; Brown et al., 2006), protection against visual loss was highly significant relative to controls during a follow-up of twelve and 24 months. Gains in visual acuity were much smaller: only 34% achieved >15 letter gain at twelve months or 24 months on the most effective dose of Ranibizumab and 65% of patients with very modest gains, no gains, or visual loss over the course of these studies. The subgroup of patients with a loss of three or more lines of visual acuity tended to have better visual acuity than average at baseline, but a larger area of CNV and a larger area of CNV leakage. Over the course of treatment, these patients had a greater growth in total lesion area and more retinal pigment epithelium abnormalities.

Fig. 5. (A) Retinograph and OCT of subretinal fibrosis of an AMD patient treated with anti-VEGF. (B) Autofluorescence of macular atrophy in the context of wet AMD that had already been treated. In both cases, the evolution of visual acuity was poor despite inactivating the lesion with repeated doses of anti-VEGF.

Furthermore a better response to intravitreal corticoids has been observed in patients who stop responding to anti-VEGF intravitreal injections (Schaal et al., 2008). Therefore we pose a future problem regarding the use of anti-VEGF, i.e., how to avoid this occurrence. One of the most appropriate options would be to find the way to reduce the number of intravitreal injections in the treatment of AMD and, to date, the only way is with combined therapies.

Long-term follow-up of patients who participated in the initial studies of anti-VEGF therapies suggests that late visual loss is often caused by processes that seem to be independent of neovascularization, particularly fibrosis and atrophy. Although more effective antiangiogenesis treatments, including combination strategies, for better blockade of new vessel formation are likely to improve outcome, it is appropriate to expand targets to other pathophysiologic processes associated with AMD. It is necessary to incorporate therapies that block fibrosis and inhibit atrophy or other pathophysiologic processes not

In Ranibizumab trials (Rosenfeld et al., 2006; Brown et al., 2006), protection against visual loss was highly significant relative to controls during a follow-up of twelve and 24 months. Gains in visual acuity were much smaller: only 34% achieved >15 letter gain at twelve months or 24 months on the most effective dose of Ranibizumab and 65% of patients with very modest gains, no gains, or visual loss over the course of these studies. The subgroup of patients with a loss of three or more lines of visual acuity tended to have better visual acuity than average at baseline, but a larger area of CNV and a larger area of CNV leakage. Over the course of treatment, these patients had a greater growth in total lesion area and more

Fig. 5. (A) Retinograph and OCT of subretinal fibrosis of an AMD patient treated with anti-VEGF. (B) Autofluorescence of macular atrophy in the context of wet AMD that had already been treated. In both cases, the evolution of visual acuity was poor despite inactivating the

**3.4 Anti-VEGF agents do not act on fibrosis and atrophy**

directly related to neovascularization.

retinal pigment epithelium abnormalities.

**A B**

lesion with repeated doses of anti-VEGF.

In a study in which 82 patients, treated with Ranibizumab monotherapy, were monitored in a follow-up of two to six years, reported that the rate of fibrosis was 50% and the rate of atrophy of the retinal pigment epithelium was 40%; 8% percent had both. The fibrosis may have been caused by ongoing inflammation and by maturation of vascular tissue. Hemorrhage above or below the subretinal pigment epithelium may have played a contributing role. Fibrosis was often observed after several years of antiangiogenesis therapy even among responders (Kaiser PK, 2009c).