Targeting vascular endothelial growth factor: a promising strategy for treating age-related macular degeneration

An insight on the anatomical and functional consequences of aflibercept therapy in age-related macular degeneration

BACKGROUND

Evaluation of anatomical and functional recovery of the retina after aflibercept therapy in neovascular age-related macular degeneration.

MATERIALS AND METHODS

This prospective study enrolled 33 eyes of 33 naive age-related macular degeneration patients with an average age of 69 (55-82) years. Following a thorough ophthalmological examination, baseline color fundus photography, optical coherence tomography and fluorescein angiography were used to assess the angiographic characteristics and classification of the lesions. Multifocal electroretinography and microperimetry were recorded. In the first three months, all patients received three consecutive intravitreal aflibercept injections on a monthly basis. After the initial three doses, non-responders received additional afibercept injections. The baseline, 3rd and 6th month data were recorded for analysis.

RESULTS

The baseline average best-corrected visual acuity (1.05 log MAR) improved dramatically to 0.9 log MAR in the 3rd and 6th months, respectively. The baseline average central macular thickness of 358.5 ± 232.1 μm decreased significantly to 273.0 ± 109.9 μm and 245.5 ± 109.3 μm in the 3rd and 6th months, respectively. The average thickness of the central 1 mm macular region decreased significantly from 349.5 ± 96.4 μm to the 3rd and 6th month values of 320.6 ± 101.9 and 290.5 ± 86.4 μm, respectively. While the mean retinal sensitivity increased significantly from 4.7 ± 3.0 dB to 6.9 ± 3.4 Db, local deficit decreased from -11.6 ± 4.6 dB to -9.4 ± 4.6 dB. Significant improvements were also observed in all rings of N1 and P1 waves.

CONCLUSION

Intravitreal aflibercept therapy resulted in significant morphological improvements that were easily identifiable during the 3rd month. Electrophysiological improvements were delayed only to become statistically significant in the 6th month. However, it has been shown that visual acuity and optical coherence tomography parameters alone may be insufficient for both the morphological and functional assessment of the retina.

Hypoxic drive caused type 3 neovascularization in a preclinical model of exudative age-related macular degeneration

Hypoxia associated with the high metabolic demand of rods has been implicated in the pathology of age-related macular degeneration (AMD), the most common cause of adult blindness in the developed world. The majority of AMD-associated severe vision loss cases are due to exudative AMD, characterized by neovascularization. To further investigate the causes and histopathology of exudative AMD, we conditionally induced hypoxia in a novel preclinical AMD model (Pde6gcreERT2/+;Vhl-/-) by targeting Vhl and used multimodal imaging and immunohistochemistry to track the development of hypoxia-induced neovascularization. In addition to developing a preclinical model that phenocopies exudative AMD, our studies revealed that the photoreceptor hypoxic response initiates and drives type 3 neovascularization, mainly in the outer retina. Activation of the VHL-HIF1a-VEGF-EPO pathway in the adult retina led to long-term neovascularization, retinal hemorrhages and compromised retinal layers. Our novel preclinical model would accelerate the testing of therapies that use metabolomic approaches to ameliorate AMD.

Novel Types of Small RNA Exhibit Sequence- and Target-dependent Angiogenesis Suppression Without Activation of Toll-like Receptor 3 in an Age-related Macular Degeneration (AMD) Mouse Model

RNA interference (RNAi) has become a powerful tool for suppressing gene expression in vitro and in vivo. A great deal of evidence has demonstrated the potential for the use of synthetic small interfering RNAs (siRNAs) as therapeutic agents. However, the application of siRNA to clinical medicine is still limited, mainly due to sequence-independent suppression of angiogenesis mediated by Toll-like receptor 3 (TLR3). Here, we describe novel types of synthetic RNA, named nkRNA and PnkRNA, that exhibit sequence-specific gene silencing through RNAi without activating TLRs or RIG-I–like receptor signaling. In addition, we confirmed the therapeutic effect for the novel types of RNA in an animal model of age-related macular degeneration (AMD) without retinal degeneration. These data indicate that nkRNA and PnkRNA are of great potential utility as therapies against blinding choroidal neovascularization due to AMD.

SLO-Microperimetry in Wet Age-Related Macular Degeneration During Anti-VEGF Therapy

BACKGROUND AND OBJECTIVE

To evaluate the morphological and functional outcome of wet age-related macular degeneration (AMD) during antivascular endothelial growth factor therapy with bevacizumab using SLO microperimetry (SLO-MP) with eye tracking.

PATIENTS AND METHODS

First, reproducibility was tested over the choroidal neovascularization (CNV) in 21 eyes of 19 patients with wet AMD. Second, 21 eyes of 19 patients with active CNV were studied longitudinally during bevacizumab therapy. Best-corrected visual acuity, SLO-MP, spectral-domain optical coherence tomography and fluorescein angiography were performed.

RESULTS

There was good reproducibility with a concordance correlation coefficient of 0.85. In the longitudinal study, eyes with anatomical response demonstrated a significant increase of retinal sensitivity. Non-responders showed no change in SLO-MP. Retinal sensitivity at baseline had a significant predictive value for the change in retinal sensitivity during therapy with bevacizumab (P=.032).

CONCLUSION

SLO-MP is able to analyze retinal function overlying lesions in wet AMD and can be a useful tool to monitor therapy in patients with macular diseases.

Improvement and optimization of standards for a preclinical animal test model of laser induced choroidal neovascularization

Background

As the murine model of laser-induced choroidal neovascularization (CNV) is becoming the most established and commonly utilized model worldwide for studying the pathogenesis of CNV and its response to treatment, specific operating standards are yet to be clarified. The purpose of this study is to compare the lesion size of CNV in mice with different ages, sex, durations of CNV process, and treated positions of laser spots, to make recommendations that may improve and optimize the quality of the model.

Methods and Results

C57/BL6 mice of different ages were treated with diode laser photocoagulation per eye and perfused with PBS containing fluorescein-labeled dextran at different time of observation. Choroid flat mounts, were then examined by fluorescence microscopy for the measurement of CNV area. Messenger-RNA expression levels of several angiogenic cytokines in eye cups of male and female C57BL/6 mice at 5–8 and 16–20 week-old were analyzed by real-time RT-PCR assay. The results showed significantly more CNV area in eyes of female mice compared to male mice with the expression level of several angiogenic cytokines elevated. 16–20-week-old female mice developed the biggest area of CNV. The mean area of CNV increased significantly at the 14^th day after photocoagulation. Laser spots delivered 1PD away from the optic disc induced the biggest area of CNV compared to those 2PD or 3PD away. Interaction of NV was observed in laser spots delivered less than 1PD away from each other.

Conclusion

The current results suggest that 16–20-week-old female C57BL/6 mice developed the most distinct CNV lesion size with laser spots delivered 1PD away from the optic disc. The best time to observe and analyze is the 14^th day after photocoagulation.

Topical bevacizumab for neovascular glaucoma: a pilot study

BACKGROUND/AIMS

Bevacizumab (Avastin), an anti-vascular endothelial growth factor drug, has been successfully used in recent years to treat ocular pathologies, mostly by intravitreal administration. The aim of this study was to investigate the safety and efficacy of topically applied bevacizumab for the treatment of neovascular glaucoma (NVG).

METHODS

Patients with NVG were treated with topical bevacizumab (25 mg/ml) 4 times daily during 2 weeks. The following parameters were evaluated at baseline and on days 3, 7 and 14: visual acuity, slit-lamp examination, intraocular pressure (IOP), heart rate and systemic blood pressure. Iris neovascularization was documented using slit-lamp color photos at baseline and on day 14.

RESULTS

Eight eyes of 8 patients with NVG were evaluated. After the 2-week treatment, mean IOP was lowered from 34.9 mm Hg (SD 12.8) at baseline to 28.8 mm Hg (SD 9.9) on day 14, representing a mean reduction of 6.1 mm Hg (17.5%). Three patients had clinical regression of their iris neovascularization. Ocular adverse events were transient and included mild upper eyelid swelling, mild exacerbation of superficial punctate keratitis and mild corneal epithelial bullae in an already edematous cornea. There were no serious systemic adverse events.

CONCLUSIONS

Topical application of bevacizumab may lower IOP and result in regression of neovascularization in patients with NVG.

High-dose topical bevacizumab for corneal neovascularization

BACKGROUND/AIMS

Bevacizumab (Avastin), an anti-vascular endothelial growth factor drug, has been successfully used in the recent years to treat ocular pathologies, mostly by intravitreal administration. The aim of the current study was to assess the off-label topical use of high-dose bevacizumab for the treatment of corneal neovascularization.

METHODS

Seventeen eyes of 17 patients with corneal neovascularization secondary to various pathologies were included. The patients were treated with topical bevacizumab (25 mg/ml) 4 times daily for 2 weeks. The following parameters were evaluated at baseline and on days 3, 7 and 14: visual acuity, slit-lamp examination, intraocular pressure, heart rate and blood pressure. Color photos were obtained at baseline and on day 14.

RESULTS

Eleven eyes (65%) demonstrated regression of corneal neovascularization and/or clearing of corneal opacification. Adverse ocular events were mild and transient, and included eyelid swelling/chalazion and superficial punctate keratitis.

CONCLUSION

Treatment with high-dose topical bevacizumab (25 mg/ml) was effective for corneal neovascularization in nearly two thirds of the eyes treated. Adverse ocular side effects were mild and transient.

Ranibizumab: a review of its use in the treatment of neovascular age-related macular degeneration

Ranibizumab (Lucentis(®)), an inhibitor of all vascular endothelial growth factor (VEGF) A isoforms, is approved for the intravitreal treatment of neovascular age-related macular degeneration (AMD). In pivotal trials, monthly injections of ranibizumab were superior to verteporfin photodynamic therapy in the treatment of predominantly classic choroidal neovascularization (CNV) due to neovascular AMD (ANCHOR) and sham in the treatment of minimally classic or occult CNV due to neovascular AMD (MARINA). Monthly or less frequent injections of ranibizumab are generally well tolerated and associated with low rates of ocular and systemic serious adverse events (SAEs). Less frequent dosing has been evaluated with the aim of reducing the burden, risk and cost of monthly injections. In the landmark CATT trial, monthly monitoring and retreatment as-needed with ranibizumab was equivalent to monthly treatment in terms of the vision gain at 1 year, but reduced the number of injections (and the related cost) by approximately one-half. In head-to-head comparisons, aflibercept administered bimonthly was noninferior to ranibizumab administered monthly (VIEW 1 and 2), bevacizumab administered monthly was equivalent to ranibizumab administered monthly (CATT), and bevacizumab administered as-needed was equivalent to ranibizumab administered as-needed (CATT). Bevacizumab is widely used (off-label) for economic reasons; while it was less costly than ranibizumab, it was associated with more systemic SAEs. Notwithstanding the availability of other similarly effective anti-VEGF therapies that are approved (aflibercept) or unapproved (bevacizumab), ranibizumab continues to set the standard as regards the totality of evidence from randomized clinical trials demonstrating its efficacy and tolerability (particularly that of the monthly regimen) in the treatment of neovascular AMD.

Aflibercept for intravitreal injection: in neovascular age-related macular degeneration

Aflibercept is a recombinant human fusion protein that acts as a soluble decoy receptor for vascular endothelial growth factor (VEGF) family members VEGF-A, VEGF-B and placental growth factor, thereby preventing these ligands from binding to, and activating, their cognate receptors. The efficacy of intravitreal aflibercept in the treatment of wet (neovascular) age-related macular degeneration has been compared with that of intravitreal ranibizumab, the current gold standard for this indication, in two pivotal phase III studies of virtually identical design (VIEW 1 and 2). In both trials, the recommended regimen of aflibercept [2 mg every second month (after three initial monthly doses)] was shown to be noninferior to the recommended regimen of ranibizumab (0.5 mg every month) in terms of the primary endpoint of the proportion of patients who maintained their vision after 1 year of treatment; similar results were seen when monthly dosing with aflibercept (0.5 or 2 mg) was compared with ranibizumab. Over a period of 96 weeks in the VIEW studies, patients receiving the recommended regimen of aflibercept during the first year followed by modified quarterly treatment during the second year had a similar visual acuity gain to those receiving the recommended regimen of ranibizumab during first year followed by modified quarterly treatment during the second year, but on average required five fewer injections. Aflibercept was generally well tolerated in the VIEW studies; the ocular and non-ocular adverse event profile of the drug was similar to that of ranibizumab.

Reduced retinal microvascular density, improved forepaw reach, comparative microarray and gene set enrichment analysis with c-jun targeting DNA enzyme

Retinal neovascularization is a critical component in the pathogenesis of common ocular disorders that cause blindness, and treatment options are limited. We evaluated the therapeutic effect of a DNA enzyme targeting c-jun mRNA in mice with pre-existing retinal neovascularization. A single injection of Dz13 in a lipid formulation containing N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium methyl-sulfate and 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine inhibited c-Jun expression and reduced retinal microvascular density. The DNAzyme inhibited retinal microvascular density as effectively as VEGF-A antibodies. Comparative microarray and gene expression analysis determined that Dz13 suppressed not only c-jun but a range of growth factors and matrix-degrading enzymes. Dz13 in this formulation inhibited microvascular endothelial cell proliferation, migration and tubule formation in vitro. Moreover, animals treated with Dz13 sensed the top of the cage in a modified forepaw reach model, unlike mice given a DNAzyme with scrambled RNA-binding arms that did not affect c-Jun expression. These findings demonstrate reduction of microvascular density and improvement in forepaw reach in mice administered catalytic DNA.

Recent Patents on Emerging Therapeutics for the Treatment of Glaucoma, Age Related Macular Degeneration and Uveitis

Advancements in the field and rising interest among pharmaceutical researchers have led to the development of new molecules with enhanced therapeutic activity. Design of new drugs which can target a particular pathway and/or explore novel targets is of immense interest to ocular pharmacologists worldwide. Delivery of suitable pharmacologically active agents at proper dose (within the therapeutic window) to the target tissues without any toxicity to the healthy ocular tissues still remain an elusive task. Moreover, the presence of static and dynamic barriers to drug absorption including the corneal epithelium (lipophilic), corneal and scleral stroma (hydrophilic), conjunctival lymphatics, choroidal vasculature and the blood-ocular barriers also pose a significant challenge for achieving therapeutic drug concentrations at the target site. Although many agents are currently available, new compounds are being introduced for treating various ocular diseases. Deeper understanding of the etiology and complex mechanisms associated with the disease condition would aid in the development of potential therapeutic candidates. Novel small molecules as well as complex biotechnology derived macromolecules with superior efficacy, safety and tolerability are being developed. Therefore, this review article provides an overview of existing drugs, treatment options, advances in emerging therapeutics and related recent patents for the treatment of ocular disorders such as glaucoma, age related macular degeneration (AMD) and uveitis.

Genetic predictors of response to photodynamictherapy

In Western countries, therapeutic management of patients affected by choroidal neovascularization (CNV) secondary to different typologies of macular degeneration represents a major health care problem. Age-related macular degeneration is the disease most frequently associated with CNV development. Schematically, CNVs can be distinguished into classic and occult subtypes, which are characterized by variable natural history and different responsiveness to some therapeutic procedures. At present, the dramatic vision loss due to CNV can be mainly treated by two interventional strategies, which are utilizable in either single or combined modalities: photodynamic therapy with verteporfin (PDT-V), and intravitreal administration of drugs acting against vascular endothelial growth factor. The combined use of PDT-V and anti-angiogenic drugs represents one of the most promising strategies against neovascular macular degeneration, but it unavoidably results in an expensive increase in health resource utilization. However, the positive data from several studies serve as a basis for reconsidering the role of PDT-V, which has undergone a renaissance prompted by the need for a more rational therapeutic approach toward CNV. New pharmacogenetic knowledge of PDT-V points to exploratory prospects to optimize the clinical application of this intriguing photothrombotic procedure. In fact, a Medline search provides data regarding the role of several single nucleotide polymorphisms (SNPs) as genetic predictors of CNV responsiveness to PDT-V. Specifically, correlations between SNPs and different levels of PDT-V efficacy have been detected by examining the gene variants influencing (i) thrombo-coagulative pathways, i.e. methylenetetrahydrofolate reductase (MTHFR) 677C>T (rs1801133), factor V (F5) 1691G>A (rs6025), prothrombin (F2) 20210G>A (rs1799963), and factor XIII-A (F13A1) 185G>T (rs5985); (ii) complement activation and/or inflammatory processes, i.e. complement factor H (CFH) 1277T>C (rs1061170), high-temperature requirement factor A1 (HTRA1) promoter -512G>A (rs11200638), and two variants of the C-reactive protein (CRP) gene (rs2808635 and rs876538); and (iii) production and bioavailability of vascular endothelial growth factor (VEGFA -2578C>A [rs699947] and rs2146323). This article critically evaluates both the clinical plausibility and the opportunity to utilize the most important SNP-response interactions of PDT-V for an effective upgrade of the current anti-CNV therapeutic scenario. In addition, the pharmacogenetics of a very severe post-PDT-V adverse event, i.e. a decrease in acute vision, is briefly discussed. A comprehensive appraisal of the findings reviewed in this article should be carefully considered to design future trials aimed at verifying (after proper genotypic stratification of the enrolled patients) whether these innovative pharmacogenetic approaches will be able to improve the multifaceted interventional management of neovascular macular degeneration.

Antivascular endothelial growth factor agents for neovascular age-related macular degeneration

Age-related macular degeneration (AMD) is the leading cause of severe visual loss and blindness over the age of 50 in developed countries. Vascular endothelial growth factor (VEGF) is considered as a critical molecule in the pathogenesis of choroidal neovascularization (CNV), which characterizes the neovascular AMD. Anti-VEGF agents are considered the most promising way of effectively inhibition of the neovascular AMD process. VEGF is a heparin-binding glycoprotein with potent angiogenic, mitogenic and vascular permeability-enhancing activities specific for endothelial cells. Two anti-VEGF agents have been approved by the US Food and Drug Administration (FDA) for the treatment of neovascular AMD. Pegaptanib sodium, which is an aptamer and ranibizumab, which is a monoclonal antibody fragment. Another humanized monoclonal antibody is currently off-label used, bevacizumab. This paper aims to discuss in details the effectiveness, the efficacy and safety of these three anti-VEGF agents. New anti-VEGF compounds which are recently investigated for their clinical usage (VEGF-trap, small interfering RNA) are also discussed for their promising outcomes.

The 1-year results of CLEAR-IT 2, a phase 2 study of vascular endothelial growth factor trap-eye dosed as-needed after 12-week fixed dosing

OBJECTIVE

To evaluate anatomic outcomes and vision, injection frequency, and safety during the as-needed (PRN) treatment phase of a study evaluating a 12-week fixed dosing period followed by PRN dosing to week 52 with vascular endothelial growth factor (VEGF) Trap-Eye for neovascular (wet) age-related macular degeneration (AMD).

DESIGN

Multicenter, randomized, double-masked trial.

PARTICIPANTS

We included 159 patients with subfoveal choroidal neovascularization (CNV) secondary to wet AMD.

METHODS

Patients were randomly assigned to 1 of 5 intravitreal VEGF Trap-Eye treatment groups: 0.5 mg or 2 mg every 4 weeks or 0.5, 2, or 4 mg every 12 weeks during the fixed-dosing period (weeks 1-12). From weeks 16 to 52, patients were evaluated monthly and were retreated PRN with their assigned dose (0.5, 2, or 4 mg).

MAIN OUTCOME MEASURES

Change in central retinal/lesion thickness (CR/LT), change in total lesion and CNV size, mean change in best-corrected visual acuity (BCVA), proportion of patients with 15-letter loss or gain, time to first PRN injection, reinjection frequency, and safety at week 52.

RESULTS

The decrease in CR/LT at week 12 versus baseline remained significant at weeks 12 to 52 (-130 μm from baseline at week 52) and CNV size regressed from baseline by 2.21 mm(2) at 48 weeks. After achieving a significant improvement in BCVA during the 12-week, fixed-dosing phase for all groups combined, PRN dosing for 40 weeks maintained improvements in BCVA to 52 weeks (5.3-letter gain; P<0.0001). The most robust improvements and consistent maintenance of visual acuity generally occurred in patients initially dosed with 2 mg every 4 weeks for 12 weeks, demonstrating a gain of 9 letters at 52 weeks. Overall, a mean of 2 injections was administered after the 12-week fixed-dosing phase, and the mean time to first reinjection was 129 days; 19% of patients received no injections and 45% received 1 or 2 injections. Treatment with VEGF Trap-Eye was generally safe and well tolerated, with few ocular or systemic adverse events.

CONCLUSIONS

PRN dosing with VEGF Trap-Eye at weeks 16-52 maintained the significant anatomic and vision improvements established during the 12-week fixed-dosing phase with a low frequency of reinjections. Repeated dosing with VEGF Trap-Eye was well tolerated over 52 weeks of treatment.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Neovascular age-related macular degeneration: opportunities for development of first-in-class biopharmaceuticals

Age-related macular degeneration (AMD) is a condition that may cause blindness. The prevalence of the disease in the Western world is estimated at 1-2% of the population. Over the past decade, treatment of neovascular AMD has been shifting from destruction of newly formed blood vessels towards inhibitors that silence the vascular endothelial growth factor (VEGF) pathway. Such agents are often first-in-class biopharmaceuticals that benefit from the fact that they can be locally administered in an immune-privileged environment with slow clearance. These new VEGF pathway inhibitors have improved therapeutic effects over conventional treatment and have promoted the identification of novel targets for inhibition of AMD angiogenesis. This review describes the rationale behind the shift from conventional to current treatment options and discusses investigational, most notably biopharmaceutical, drugs that are in clinical trials. It also provides possible points for improvement of these treatments, specifically regarding their delivery.

Long-term efficacy and safety of ranibizumab administered pro re nata in Japanese patients with neovascular age-related macular degeneration in the EXTEND-I study

PURPOSE

To evaluate the long-term efficacy and safety of ranibizumab administered pro re nata (PRN) in Japanese patients with choroidal neovascularization secondary to age-related macular degeneration during the extension phase of the EXTEND-I study.

METHODS

EXTEND-I, an open-label, multicenter, Phase I ⁄ II study comprised: a single-injection (Group A); a multiple-injection (Groups A and B; the latter consisted of patients who did not participate in the single-injection phase); and an extension phase. In the extension phase, a PRN regimen of ranibizumab (0.3 or 0.5 mg) guided by monthly best-corrected visual acuity (BCVA) score and other ophthalmic examinations was employed. The efficacy variables included the mean BCVA change from Month 12 to the last visit in Group B. Safety was assessed in all patients.

RESULTS

In the extension phase, efficacy was assessed only in Group B patients. The number of ranibizumab injections per year in the 0.3 and 0.5 mg Group B patients was 4.19 and 4.27, respectively. The mean BCVA change (SD) from Month 12 to the last visit was )3.6 (14.82) letters for 0.3 mg (n = 28) and )2.2 (7.92) letters for 0.5 mg groups (n = 33) in Group B. Conjunctival haemorrhage and nasopharyngitis were the most commonly reported adverse events. Of the 13 serious adverse events reported, cerebral infarction (two incidences) was suspected to be study-drug related.

CONCLUSIONS

Pro re nata regimen of ranibizumab guided by monthly BCVA and other ophthalmic examinations appears effective in sustaining the BCVA gained with 12 monthly injections while reducing the number of injections during the extension phase. Ranibizumab was well tolerated during the extension phase.

Treatment of diabetic retinopathy with anti-VEGF drugs

The aim of this review is to summarize the latest developments in the treatment of diabetic retinopathy (DR) with anti-vascular endothelial growth factor (VEGF) drugs. We reviewed recent studies that evaluated the role of the anti-VEGF agents bevacizumab, ranibizumab and pegaptanib in the treatment of DR. There was only one large randomized controlled trial that evaluated the role of ranibizumab in diabetic macular oedema (DME). Other prospective and retrospective studies provided important insight into the role of anti-VEGF drugs in DR, but most of them were not conducted in large scales. The growing evidence indicates that anti-VEGF drugs are beneficial in DR, especially in DME. Further studies are needed to fully evaluate the role of these agents, especially in proliferative DR and in DR candidates for vitrectomy surgery.

Efficacy and safety of monthly versus quarterly ranibizumab treatment in neovascular age-related macular degeneration: the EXCITE study

OBJECTIVE

To demonstrate noninferiority of a quarterly treatment regimen to a monthly regimen of ranibizumab in patients with subfoveal choroidal neovascularization (CNV) secondary to age-related macular degeneration (AMD).

DESIGN

A 12-month, multicenter, randomized, double-masked, active-controlled, phase IIIb study.

PARTICIPANTS

Patients with primary or recurrent subfoveal CNV secondary to AMD (353 patients), with predominantly classic, minimally classic, or occult (no classic component) lesions.

INTERVENTION

Patients were randomized (1:1:1) to 0.3 mg quarterly, 0.5 mg quarterly, or 0.3 mg monthly doses of ranibizumab. Treatment comprised of a loading phase (3 consecutive monthly injections) followed by a 9-month maintenance phase (either monthly or quarterly injection).

MAIN OUTCOME MEASURES

Mean change in best-corrected visual acuity (BCVA) and central retinal thickness (CRT) from baseline to month 12 and the incidence of adverse events (AEs).

RESULTS

In the per-protocol population (293 patients), BCVA, measured by Early Treatment Diabetic Retinopathy Study-like charts, increased from baseline to month 12 by 4.9, 3.8, and 8.3 letters in the 0.3 mg quarterly (104 patients), 0.5 mg quarterly (88 patients), and 0.3 mg monthly (101 patients) dosing groups, respectively. Similar results were observed in the intent-to-treat (ITT) population (353 patients). The mean decrease in CRT from baseline to month 12 in the ITT population was -96.0 μm in 0.3 mg quarterly, -105.6 μm in 0.5 mg quarterly, and -105.3 μm in 0.3 mg monthly group. The most frequent ocular AEs were conjunctival hemorrhage (17.6%, pooled quarterly groups; 10.4%, monthly group) and eye pain (15.1%, pooled quarterly groups; 20.9%, monthly group). There were 9 ocular serious AEs and 3 deaths; 1 death was suspected to be study related (cerebral hemorrhage; 0.5 mg quarterly group). The incidences of key arteriothromboembolic events were low.

CONCLUSIONS

After 3 initial monthly ranibizumab injections, both monthly (0.3 mg) and quarterly (0.3 mg/0.5 mg) ranibizumab treatments maintained BCVA in patients with CNV secondary to AMD. At month 12, BCVA gain in the monthly regimen was higher than that of the quarterly regimens. The noninferiority of a quarterly regimen was not achieved with reference to 5.0 letters. The safety profile was similar to that reported in prior ranibizumab studies.

Effect of zeaxanthin and antioxidant supplementation on vascular endothelial growth factor (VEGF) expression in apolipoprotein-E deficient mice

PURPOSE

Apolipoprotein E(-/-) deficient (apoE(-/-)) mice develop hypercholesterolemia, atherosclerosis, and retinal alterations. We studied the oxidative status and vascular endothelial growth factor (VEGF) expression in murine retinal pigment epithelium-choroid (RPE) and Bruch's membrane (BM) ultrastructure and the effect of zeaxanthin.

METHODS

Ten 6-month-old C57BL/6 and 40 apoE(-/-) mice were divided into four groups (n = 10 each) and fed different diets for 12 weeks based on body weight: wild type (WT) and apoE(-/-) (AE-Con) mice standard rodent chow; apoE(-/-) mice (AES) standard rodent chow with ascorbate (800 mg/kg), tocopherol (1053 mg/kg), and zinc (135 mg/kg); and apoE(-/-) mice the last diet plus zeaxanthin with either 0.4 g/kg (AES-Z04) or 4 g/kg feed (AES-Z4).

RESULTS

Plasma total cholesterol (TC) and triglycerides (TG) and urine lipid peroxidation (isoprostanes) were measured. VEGF expression was determined in RPE-choroid homogenates. Zeaxanthin uptake was assessed in liver and retina by high-performance liquid chromatography; the retinal ultrastructure was analyzed by electron microscopy. AE-Con mice had higher plasma TC (p < 0.001) and TG (p < 0.001) values than WT mice. AE-Con mice had higher RPE-choroid-VEGF levels than WT mice (p < 0.05), BM thickness (p < 0.001) and presence of basal laminar deposits (BLamD). AES-Z4 resulted in lower urinary isoprostanes (p = 0.054) and lower VEGF expression in the RPE-choroid (p < 0.01). BM in the AES-Z4 animals had less confluent BLamD than AE-Con, AES, or AES-Z04 animals.

CONCLUSIONS

We have reported that supplementation with zeaxanthin and antioxidants may delay or reverse alterations in the RPE and deposits in BM, and reduced VEGF expression observed in apoE(-/-) mice.

Drug and light dose responses to focal photodynamic therapy of single blood vessels in vivo

As part of an ongoing program to develop two-photon (2-gamma) photodynamic therapy (PDT) for treatment of wet-form age-related macular degeneration (AMD) and other vascular pathologies, we have evaluated the reciprocity of drug-light doses in focal-PDT. We targeted individual arteries in a murine window chamber model, using primarily the clinical photosensitizer Visudyne/liposomal-verteporfin. Shortly after administration of the photosensitizer, a small region including an arteriole was selected and irradiated with varying light doses. Targeted and nearby vessels were observed for a maximum of 17 to 25 h to assess vascular shutdown, tapering, and dye leakage/occlusion. For a given end-point metric, there was reciprocity between the drug and light doses, i.e., the response correlated with the drug-light product (DLP). These results provide the first quantification of photosensitizer and light dose relationships for localized irradiation of a single blood vessel and are compared to the DLP required for vessel closure between 1-gamma and 2-gamma activation, between focal and broad-beam irradiation, and between verteporfin and a porphyrin dimer with high 2-gamma cross section. Demonstration of reciprocity over a wide range of DLP is important for further development of focal PDT treatments, such as the targeting of feeder vessels in 2-gamma PDT of AMD.

Off-label use of bevacizumab for the treatment of age-related macular degeneration: what is the evidence?

There is an active and controversial debate about the role of intravitreal bevacizumab versus approved drugs in the treatment of neovascular age-related macular degeneration (AMD). Because bevacizumab was available prior to the launch of ranibizumab, off-label use of the former became widespread and the cancer drug bevacizumab is the most commonly used medication in ophthalmology nowadays. This review considers every publication identified in MEDLINE using the keywords 'bevacizumab' and 'Avastin' between 1 June 2005 and 31 July 2008. The search identified 511 papers that were evaluated. In 33 studies, there was consistent and clear evidence for the efficacy of bevacizumab in neovascular AMD. However, the highest grade studies (three prospective, randomized, controlled trials) did not attain better than grade 2b level of evidence, and objective evaluation of the benefit of bevacizumab relative to representative controls was therefore not possible. Certainly, the available evidence is inferior to that obtained from the approval studies of ranibizumab and this should influence treatment selection and guidance of patients. These considerations indicate that important quality criteria need to be included in future studies to ensure more meaningful conclusions can be drawn. These include clearly defined inclusion criteria, information about the recruitment procedure (including data on withdrawals, excluded patients, concealed treatment allocation, use of intention-to-treat analyses and blinded assessment procedures). Although preclinical studies have almost exclusively found bevacizumab to be safe, the design utilized in clinical case series cannot rule out a possible increase in adverse events, which already show a high spontaneous incidence in elderly AMD patients. The superior evidence level for ranibizumab and the limited safety data for bevacizumab must be taken into consideration when evaluating the costs that a healthcare system is willing to spend. However, the superior grade of evidence for ranibizumab should not be confused with the (still missing) evidence for superior efficacy. The results of ongoing randomized, controlled, comparative trials will provide further data on the efficacy and cost effectiveness of bevacizumab and ranibizumab in the treatment of AMD. In the meantime, patients should be informed about the alternatives, the price differences and the restricted liability issue when off-label use of bevacizumab is offered.

Review of the ocular angiogenesis animal models

Increasing interest in developing reliable and reproducible models to study angiogenesis has emerged due to recent advances in the treatment of eye disease with pathologic angiogenesis. This review provides a summary of the principal ocular animal models for angiogenesis. Models of anterior segment neovascularization include the corneal micropocket assay, used to study the influence of specific molecules/proteins in angiogenesis, and corneal chemical and suture induced injury, which mimic more closely the complex nature of the human disease. Angiogenesis models of the posterior segment include the well-known laser-induced injury of the choroid/Bruch's membrane, as well as the oxygen induced retinopathy and models of injections of pro-angiogenic/inflammatory molecules. In addition, knockout or knock-in transgenic mice provide powerful tools in studying the role of specific proteins in angiogenesis.

Cytoprotective effects of a blue light-filtering intraocular lens on human retinal pigment epithelium by reducing phototoxic effects on vascular endothelial growth factor-alpha, Bax, and Bcl-2 expression

PURPOSE

To compare the possible protective effects of the ultraviolet (UV)-filtering and blue light-filtering SN60AT intraocular lens (IOL) and the untinted UV-filtering SA60AT IOL with regard to light-induced stress on human retinal pigment epithelium (RPE).

SETTING

Department of Ophthalmology, Ludwig-Maximilians-University, Munich, Germany.

METHODS

Primary human RPE cells were exposed to white light, and a tinted or untinted IOL was placed in the light beam. After 15 to 60 minutes of irradiation, cell viability was determined by a colorimetric test (tetrazolium dye-reduction assay) and a microscopic live/dead assay. The expression of vascular endothelial growth factor-alpha (VEGF-alpha), Bax, and Bcl-2 and their mRNA was determined by reverse-transcription polymerase chain reaction (RT-PCR) and Western blotting.

RESULTS

Without an IOL, white-light exposure decreased cell viability compared with the decrease with the nonirradiated control in a time-dependent manner. Light-induced cell death was significantly reduced by both the tinted IOL and untinted IOL. The combined UV and blue-light filtering attenuated light-induced cell damage significantly more than UV filtering alone. Results of RT-PCR and Western blotting showed a significant time-dependent decrease in Bcl-2 and increase in Bax and VEGF-alpha that were significantly less with the tinted IOL than with the untinted IOL.

CONCLUSIONS

Both IOLs reduced light-induced RPE damage. The UV- and blue light-filtering IOL reduced damage more than the conventional IOL. This supports the hypothesis that blue light-filtering IOLs may prevent retinal damage in clinical use.

Verteporfin combination regimens in the treatment of neovascular age-related macular degeneration

BACKGROUND

Neovascular age-related macular degeneration is characterized by choroidal neovascularization that has a complex pathogenesis. Combining agents that have different mechanisms of action (i.e., verteporfin photodynamic therapy, antivascular endothelial growth factor, and/or anti-inflammatory therapies) could maximize clinical benefits through potential complementary effects. This review discusses findings from studies investigating this hypothesis.

METHODS

Articles were retrieved from PubMed using relevant search terms. Abstracts from recent scientific meetings and details of ongoing trials from clinicaltrials.gov were also included.

RESULTS

Following its approval, verteporfin was important in the management of choroidal neovascularization due to age-related macular degeneration for several years. Improved visual outcomes have now been reported with antiangiogenic agents (e.g., intravitreal ranibizumab), especially when frequently administered. Results from investigator-sponsored trials, retrospective case studies and Registries, which have provided insights into the latest findings from clinical practice in the "real-world" setting, as well as randomized controlled trials, suggest that a combination approach is generally well tolerated and may maintain improvements in visual and anatomic outcomes with fewer retreatments.

CONCLUSION

A rationale exists for investigating combination approaches to target different processes in choroidal neovascularization pathogenesis, which may optimize treatment benefits in neovascular age-related macular degeneration. Encouraging data suggest that combination strategies are not associated with major adverse events.

Predictive role of C677T MTHFR polymorphism in variable efficacy of photodynamic therapy for neovascular age-related macular degeneration

Age-related macular degeneration (AMD) complicated by subfoveal choroidal neovascularization (CNV) is the leading cause of severe central blindness in developed countries. AMD-related CNVs are distinguishable in classic and occult subtypes, characterized by variable natural history and different responsiveness to therapeutic procedures. Combined and repeated use of photodynamic therapy with verteporfin (PDT-V) and antiangiogenic drugs represents the most promising strategy against neovascular AMD, but it is unavoidably associated with mounting health-resource utilization. Predictive correlations between peculiar coagulation-balance gene variants and different levels of post-PDT-V benefit have recently been documented in Caucasians with AMD-related CNVs. In particular, methylenetetrahydrofolate reductase C677T substitution, a common thrombophilic folate pathway genotypic polymorphism, influences a better CNV responsiveness to PDT-V in classic- but not in occult-CNV cases. These pharmacogenetic findings indicate the opportunities to optimize the eligibility criteria of PDT-V and/or to perform this intriguing therapy in a customized manner, for finally minimizing the socio-economic burden of neovascular AMD.

Intravitreal bevacizumab (Avastin) injection for neovascular glaucoma: a survey on 23 cases throughout 12-month follow-up

AIMS

Neovascular glaucoma (NVG) represents one of the most severe forms of secondary glaucoma, caused by a number of ocular and systemic conditions, which share the common element of retinal ischaemia/hypoxia that initiates the subsequent release of angiogenesis factors, with consequent development of new abnormal vessels through the ciliary body. The aim was to examine the potential efficacy and safety of intravitreal injection of bevacizumab (IVB) (Avastin) in the treatment of NVG in patients who had already undergone the standard retinal ablative procedure.

METHODS

This was a prospective pilot trial. Clinical data of 26 eyes from 23 patients, including diagnosis, visual acuity, iris fluorescein angiography stage and intraocular pressure (IOP), were collected. Three injections of bevacizumab were scheduled for each recruited eye at 4-week intervals from the start. All investigations were repeated the day before the IVB (1.25 mg/0.05 ml) and at the 1-, 3-, 6-, 9- and 12-month follow-up.

RESULTS

Regression of corneal oedema together with significant pain reduction was achieved in all eyes already after the first IVB, without any noteworthy improvement of visual acuity. At the end of the scheduled protocol (three IVB), regression of iris neovascularization was documented in all patients, together with significant improvement of visual acuity. The IOP reduction from baseline ranged from 30 to 0 mmHg (12.1 +/- 8 mmHg).

CONCLUSIONS

Intravitreal bevacizumab, as adjunctive treatment to the standard retinal ablative procedure, seems promising for the management of conditions responsible of retinal ischaemia/hypoxia associated with NVG.

Clinical and histological aspects of CNV formation: studies in an animal model

The purpose of the present thesis was to develop an animal model of CNV in order to study the early formation of CNV and to test the effects of an anti-angiogenic treatment. Porcine eyes were chosen as a substrate for CNV induction, since they are similar to human eyes in terms of both macroscopic and microscopic morphology. However, a major difference is that pigs lack a fovea; instead they have a visual streak, with a relatively stable and high concentration of cones. By surgical perforation of Bruch's membrane we were able to induce formation of CNV membranes. The morphology and cellular composition of these membranes varied with the surgical technique employed. When RPE cells were locally removed at the time of perforation, the resulting CNV was thinner, contained fewer blood vessels and was less prone to leak on fluorescein angiography than when RPE cells were left intact at induction. The neuroretina overlying the perforation site was not damaged by any of the surgical techniques, thus allowing the subsequent retinal damage to be ascribed to the actual process of CNV formation. Using this animal model allowed us to directly map histological findings onto fluorescein angiograms and thereby perform meaningful correlations between histopathologic and photographic features. Such correlations have been hampered in human subjects, since human eyes are not enucleated as a consequence of CNV and are therefore only available for post-mortem studies. In such studies there often is a considerable time-gap between the death of the patient and the latest available fluorescein angiogram, thereby allowing macular pathology to evolve in the interim. Histological examination of the porcine membranes demonstrated that they were composed of RPE cells, glial cells, macrophages, endothelial cells, collagen and smooth muscle fibres, which are the same cellular and fibrillar elements that dominate human CNV membranes. The porcine model was applied to test the effects, in a randomized and masked fashion, of intravitreally injected bevacizumab. Bevacizumab, a pan VEGF A antibody, was found to reduce both the proliferation of endothelial cells in CNV membranes and the propensity to leak in fluorescein angiograms. Immunohistochemically, bevacizumab was detected in the inner limiting membrane, in retinal blood vessels and binding uniformly to the entire CNV membrane without any cellular predisposition. Based on the above findings we believe that the porcine CNV model shows a bearing to human disease and therefore might be used as a tool to obtain improved treatments for this debilitating condition.

Vascular endothelial growth factor mediates corneal nerve repair

PURPOSE

To examine the expression of vascular endothelial growth factor (VEGF) and its receptors in the cornea and the trigeminal ganglion and to characterize the role of VEGF in mediating corneal nerve repair.

METHODS

Regeneration of the corneal subbasal nerve plexus after epithelial debridement was measured. The expression of VEGF and its receptors was examined in the trigeminal ganglia and in the cornea by RT-PCR, immunohistochemistry, and Western blotting. VEGF-mediated nerve growth was measured in a trigeminal ganglia explant assay. Anti-VEGF neutralizing antibody was used to examine the VEGF-dependent growth of neurons in vitro and regeneration of the corneal nerves in vivo.

RESULTS

After two distinct patterns of nerve regeneration, the subbasal nerves recovered to 65% of the preinjury density after 28 days. RT-PCR demonstrated gene expression of VEGF and VEGF receptors in the trigeminal ganglia. Immunohistochemistry showed staining for VEGF and its receptors in the trigeminal ganglia and for VEGFR1, VEGFR2, and neuropilin (NRP)-1 in the cornea. Western blot confirmed these results. In vitro, VEGF promoted the growth of explanted trigeminal ganglia by 91%. Blockage of VEGF signaling with anti-VEGF antibody reduced the growth of cultured neurons by 17% and the regeneration of subbasal neurons by 23%.

CONCLUSIONS

In addition to providing new information on the regeneration of murine corneal nerves, this study presents evidence that VEGF signaling influences the repair of corneal nerves by demonstrating that VEGF and VEGF receptors are present in the trigeminal ganglia and that abrogation of VEGF signaling reduces nerve growth in vitro and in vivo.