Vascular endothelial growth factor biology: clinical implications for ocular treatments

Corneal neovascularization and biological therapy

Corneal avascularity is necessary for the preservation of optimal vision. The cornea maintains a dynamic balance between pro- and antiangiogenic factors that allows it to remain avascular under normal homeostatic conditions. Corneal neovascularization (NV) is a condition that can develop in response to inflammation, hypoxia, trauma, or limbal stem cell deficiency and it is a significant cause of blindness. New therapeutic options for diseases of the cornea and ocular surface are now being explored in experimental animals and clinical trials. Antibody based biologics are being tested for their ability to reduce blood and lymphatic vessel ingrowth into the cornea, and to reduce inflammation. Numerous studies have shown that biologics with specificity for VEGF A such as bevacizumab and ranibizumab (a recombinant antibody and an antibody fragment, respectively) or anti-tumor necrosis factor-α microantibody, are effective in the treatment of corneal neovascularization.

Influence of ranibizumab treatment on the extracellular matrix in patients with neovascular age-related macular degeneration

BACKGROUND

We know the influence of the intravitreal anti-vascular endothelial growth factor (VEGF) injections on the choroidal neovascularization in the course of exudative age-related macular degeneration (AMD). However, the influence of the ranibizumab therapy in question on the extracellular matrix (ECM) remains unknown. We aimed to estimate the influence of Lucentis intravitreal injections on the gene expression of structural components of the extracellular matrix in patients with neovascular AMD.

MATERIAL AND METHODS

Patients with subfoveal localization of neovascularization in AMD, which was clinically active and observed using optical coherence tomography, were treated with ranibizumab (0.5 mg/0.05 mL) in accordance with the PrONTO scheme. Total RNA was extracted from peripheral blood mononuclear cells, and an oligonucleotide microarray technique enabled comparison of the expression level of genes encoding collagens, elastin, and laminins in AMD patients compared to control subjects.

RESULTS

After 3 intravitreal injections of ranibizumab (Lucentis), COL1A1 and COL6A1 genes showed increased expression, whereas decreased expression mainly occurred for the following genes: COL4A5, COL11A1, OL4A6C, LAMB4, and LAMC2.

CONCLUSIONS

Anti-VEGF local therapy influences the gene expression of structural components of the ECM as measured from blood samples. The loading dose of ranibizumab for the retina changes the expression of collagen and laminin genes, but does not influence the expression of the elastin gene.

Sema3A maintains corneal avascularity during development by inhibiting Vegf induced angioblast migration

Corneal avascularity is important for optical clarity and normal vision. However, the molecular mechanisms that prevent angioblast migration and vascularization of the developing cornea are not clear. Previously we showed that periocular angioblasts and forming ocular blood vessels avoid the presumptive cornea despite dynamic ingression of neural crest cells. In the current study, we investigate the role of Semaphorin3A (Sema3A), a cell guidance chemorepellent, on angioblast migration and corneal avascularity during development. We show that Sema3A, Vegf, and Nrp1 are expressed in the anterior eye during cornea development. Sema3A mRNA transcripts are expressed at significantly higher levels than Vegf in the lens that is positioned adjacent to the presumptive cornea. Blockade of Sema3A signaling via lens removal or injection of a synthetic Sema3A inhibitor causes ectopic migration of angioblasts into the cornea and results in its subsequent vascularization. In addition, using bead implantation, we demonstrate that exogenous Sema3A protein inhibits Vegf-induced vascularization of the cornea. In agreement with these findings, loss of Sema/Nrp1 signaling in Nrp1(Sema-) mutant mice results in ectopic angioblasts and vascularization of the embryonic mouse corneas. Altogether, our results reveal Sema3A signaling as an important cue during the establishment of corneal avascularity in both chick and mouse embryos. Our study introduces cornea development as a new model for studying the mechanisms involved in vascular patterning during embryogenesis and it also provides new insights into therapeutic potential for Sema3A in neovascular diseases.

Retinal and Choroidal Thickness Changes after Single Anti-VEGF Injection in Neovascular Age-related Macular Degeneration: Ranibizumab vs Bevacizumab

Purpose

To evaluate and compare the effects of single intravitreal injection of ranibizumab and bevacizumab on central retinal and choroidal thickness in patients with neovascular age-related macular degeneration (AMD).

Methods

Forty eyes of 40 patients with neovascular AMD that underwent intravitreal injection of vascular endothelial growth factor inhibitors (anti-VEGFs) were included. Patients were randomized into 2 groups: 20 eyes received ranibizumab and 20 eyes received bevacizumab injection. Central retinal and choroidal thicknesses of all eyes at baseline and 1 month postinjection scans were measured with Fourier-domain optical coherence tomography (OCT). Student t test and Mann-Whitney U test were used to compare the data.

Results

The mean central retinal thickness (CRT) showed significant decrease after single injection of ranibizumab (from 345.0 μm to 253.5 μm, p<0.01) and bevacizumab (from 329.5 μm to 251.0 μm, p<0.01) at the first month, respectively. There was no significant difference regarding the CRT change between groups (p = 0.39). The mean choroidal thickness decreased from 158.6 μm (115-317) to 155.5 μm (111-322) in the ranibizumab group and from 211.5 μm (143-284) to 201.5 μm (93-338) in bevacizumab group. The decrease was not significant between groups (p = 0.35).

Conclusions

Intravitreal injection of both ranibizumab and bevacizumab provided a significant decrease in CRT; however, the agents caused no significant change in choroidal thickness. Additionally, no difference between ranibizumab versus bevacizumab was observed related to macular edema inhibition.

Vaccination with a mutated variant of human Vascular Endothelial Growth Factor (VEGF) blocks VEGF-induced retinal neovascularization in a rabbit experimental model

Vascular Endothelial Growth Factor (VEGF) is a key driver of the neovascularization and vascular permeability that leads to the loss of visual acuity of eye diseases like wet age-related macular degeneration, diabetic macular edema, and retinopathy of premature. Among the several anti-VEGF therapies under investigation for the treatment of neovascular eye diseases, our group has developed the vaccine candidate CIGB-247-V that uses a mutated form of human VEGF as antigen. In this work we evaluated if the vaccine could prevent or attenuate VEGF-induced retinal neovascularization in the course of a rabbit eye neovascularization model, based on direct intravitreal injection of human VEGF. Our experimental findings have shown that anti-VEGF IgG antibodies induced by the vaccine were available in the retina blood circulation, and could neutralize in situ the neovascularization effect of VEGF. CIGB-247-V vaccination proved to effectively reduce retinal neovascularization caused by intravitreal VEGF injection. Altogether, these results open the way for human studies of the vaccine in neovascular eye syndromes, and inform on the potential mechanisms involved in its effect.

Short term apoptotic activity of intravitreal bevacizumab on rabbit retina

AIM

To evaluate the safety and the short term apoptotic activity of intravitreal bevacizumab in rabbit eyes by histopathological analysis.

METHODS

Twenty-eight eyes of 14 rabbits were divided into three groups: 8 rabbits in group 1 and 3 rabbits in each of group 2 and group 3. Intravitreal bevacizumab (1.25mg/0.05mL) was applied to the right eyes of each subject in group 1 and group 2 (11 eyes) and the same volume of saline was applied to the left eyes of each subject in group 1 and group 3 (11 eyes). The left eyes in group 2 and the right eyes in group 3 were left untreated and used as control. Enucleated eyes were used for histopathologic analyses.

RESULTS

After immunohistochemical staining with caspase-3 and p53, there was no histological evidence of toxicity to the retina and the optic nerve in any of the sections that were analyzed in all three groups. In addition, vascular endothelial cells located at the retina and the optic nerve tissues in all groups showed a similar staining pattern with caspase-3 and p53.

CONCLUSION

Our study showed that intravitreal bevacizumab with the dose of 1.25mg/0.05mL caused no histological signs of toxicity or apoptotic activity on the rabbit retina.

Elevated cell proliferation and VEGF production by high-glucose conditions in Müller cells involve XIAP

PURPOSE

Müller cells have important roles in the pathogenesis of diabetic retinopathy by promoting cell proliferation and inducing the production of vascular endothelial growth factor (VEGF) under hyperglycemic conditions. The objective of this study was to determine the potential mechanism of Müller cell proliferation and VEGF production due to high-glucose conditions.

METHODS

Primary cultured rat Müller cells were incubated with medium containing variable concentrations of glucose and/or embelin, a specific inhibitor of X-linked inhibitor of apoptosis protein (XIAP), for 72 h. The proliferation of Müller cells was assessed by the MTT assay. The expression and/or phosphorylation of 146 proteins were assessed using protein pathway array.

RESULTS

High concentrations of glucose-induced Müller cell proliferation and altered expression and/or phosphorylation of 47 proteins that have been identified to have key roles in several important signaling pathways (XIAP, VEGF, HIF1α, NFκB, etc) and are involved in the regulation of cell survival, proliferation, or apoptosis. However, Müller cell alterations induced by high-glucose conditions were counteracted by the XIAP inhibitor embelin, and 26 proteins/phosphorylations (out of 47) were restored to their normal levels. Nine proteins, including NFκB p65, p-p38, tumor necrosis factor-α, urokinase-type plasminogen activator, CREB, IL-1β, HCAM, estrogen receptor-α, and p-Stat3, were involved in regulatory networks between XIAP and VEGF.

CONCLUSIONS

The current study suggests that XIAP may be a potential regulator that can mediate a series of pathological changes induced by high-glucose conditions in Müller cells. Therefore, embelin could be a potential agent for the prevention and treatment of diabetic retinopathy.

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.

Development of a multiplex sandwich aptamer microarray for the detection of VEGF165 and thrombin

In this work we have developed a multiplex microarray system capable of detecting VEGF₁₆₅ and thrombin. We recently described a Sandwich Aptamer Microarray (SAM) for thrombin detection feasible for use in multiplex microarrays; here we describe a new aptasensor for VEGF₁₆₅ detection employing Vap7 and VEa5, two DNA aptamers recognizing different sites of the protein. The aptamers were modified to be adapted to the solid phase platform of SAM and their capability to simultaneously recognize VEGF₁₆₅ by forming a ternary complex was analyzed in solution. Having so defined the best tandem arrangement of modified aptamers, we set up the aptasensor for VEGF₁₆₅, and finally analyzed the multiplex system with the two aptasensors for the simultaneous detection of VEGF₁₆₅ and thrombin. The results indicate that each sandwich is specific, even when the two proteins are mixed. The system performance is consistent with the behavior evidenced by the biochemical analysis, which proves to be valuable to drive the evaluation and refinement of aptamers prior to or along the development of a detection platform. Since thrombin upregulates VEGF expression, the simultaneous recognition of these two proteins could be useful in the analysis of biomarkers in pathologies characterized by neo-angiogenesis.

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.

Intravitreal ranibizumab in choroidal neovascularisation due to multifocal choroiditis and panuveitis syndrome

We report the use of intravitreal ranibizumab as initial and only treatment in a case of peripapillary choroidal neovascularisation (CNV) in a patient with multifocal choroiditis and panuveitis (MCP) syndrome. A 54-year-old woman presented with sudden reduced vision in the right eye of 2 weeks duration. A full ophthalmological examination was performed including biomicroscopy, fluorescein angiography and optical coherence tomography. A peripapillary choroidal neovascular membrane with subretinal haemorrhage extending to the fovea was revealed due to MCP syndrome. Three intravitreal injections of ranibizumab were performed with monthly intervals. There was clearance of the subretinal haemorrhage and reduction of the leakage after the first injection. The visual acuity improved to 20/20 in 3 months and remained stable at 2-year follow-up without angiographical leakage. Intravitreal injections of ranibizumab could be tried in cases of CNV due to MCP syndrome with very good response.

Can intravitreal ranibizumab alter retrobulbar circulation in eyes with age-related macular degeneration?

PURPOSE

To determine the effect of a single intravitreal ranibizumab injection on retrobulbar circulation in cases with neovascular age-related macular degeneration (AMD).

METHODS

In this prospective and interventional study, 32 patients with neovascular AMD were enrolled. A single intravitreal ranibizumab dose was in only 1 eye per patient. Peak systolic velocity, end-diastolic velocity, resistive index and pulsatility index values in the common carotid artery, ophthalmic artery, central retinal artery, nasal posterior ciliary artery, and temporal posterior ciliary artery in both injected and uninjected healthy fellow eyes were measured using color Doppler ultrasonography at baseline and 1 week and 1 month after the injection of ranibizumab.

RESULTS

All measurements revealed no statistically significant difference among baseline, first week, and first month after injection measurements for all parameters measured in all arteries in both the injected and uninjected healthy fellow eyes.

CONCLUSION

A single intravitreal injection of ranibizumab does not significantly affect on retrobulbar circulation of either the injected or the uninjected healthy fellow eyes with neovascular AMD.

Comparison of subconjunctivally injected bevacizumab, ranibizumab, and pegaptanib for inhibition of corneal neovascularization in a rat model

AIM

To compare the efficacies of subconjunctival bevacizumab, ranibizumab, and pegaptanib sodium injections for the inhibition of corneal neovascularization in an experimental rat model.

METHODS

Sixteen corneas of 16 rats were chemically cauterized and randomized into four groups: bevacizumab group that treated with 0.05mL/1.25mg bevacizumab, ranibizumab group that treated with 0.05mL/0.5mg ranibizumab, pegaptanib group that treated with 0.05mL/0.15mg pegaptanib sodium, and control group that treated with 0.05mL saline solution. Digital photographs of the corneas were taken and analyzed using an image analysis software program. All corneas were excised and examined histologically on the 15(th) day.

RESULTS

Each treatment group had significantly less neovascularized corneal areas and fewer blood vessels than the control group (all P<0.05). In addition, bevacizumab group had significantly less neovascularized corneal areas and fewer blood vessels than ranibizumab and pegaptanib groups (both P<0.05). However, there was no significant difference between the ranibizumab and pegaptanib groups regarding percentage of neovascularized corneal areas and number of blood vessels (both P>0.05).

CONCLUSION

Subconjunctival bevacizumab, ranibizumab, and pegaptanib sodium were effective with no corneal epitheliopathy for inhibiting corneal neovascularization after corneal burn in rats. Bevacizumab was more effective than ranibizumab and pegaptanib sodium.

Pharmacogenetics of antiangiogenic and antineovascular therapies of age-related macular degeneration

Age-related macular degeneration (AMD), the most common age-related disease causing irreversible visual loss in industrialized countries, is a complex and multifactorial illness. Researchers have found components of the complement alternative pathway inside drusen and Bruch's membrane of AMD patients, underlying a possible important role of complement factor H in the pathogenesis of AMD. The neovascular (wet) AMD is the most destructive form and it is characterized by invasion of new blood vessels into subretinal spaces with subsequent exudation and bleeding, resulting in scarring of the macular region and loss of the central vision. The hallmark of the neovascular form is the choroidal neovascularization, where VEGF-A has an important role in the pathogenesis of the disease. SNPs of these genes have recently been investigated as potential pharmacogenetic markers of the antiangiogenic and antineovascular therapy of AMD, which includes verteporfin photodynamic therapy and anti-VEGF-A drugs, such as pegaptanib, bevacizumab and ranibizumab. The CFH rs1061170 CT and TT genotypes have been associated with an improvement of visual acuity in bevacizumab or ranibizumab treated patients, whereas patients harboring VEGF-A rs699946 G allele responded better to bevacizumab-based therapy if compared with patients carrying the A allele. In conclusion, the discovery of pharmacogenetic markers for the personalization of the antiangiogenic and/or antineovascular therapy could be, in the future, a key issue in ophthalmology to obtain a personalization of the therapy and to avoid unnecessary costs and adverse drug reactions.

Effects of subconjunctival ranibizumab in a presensitized rat model of corneal graft

We evaluated whether corneal graft survival in presensitized corneal transplantation was affected by subconjunctival ranibizumab in a rat model. The effect of ranibizumab in the presensitized corneal transplantation has not been previously reported, although anti-VEGF was attempted on a non-presensitized model in other studies. Corneas were transplanted from Brown Norway to Spraque Dawley rats. The recipient rats were randomly assigned to three groups: Group 1, skin autograft and subconjunctival injection of PBS; Group 2, skin allograft and injection of PBS; and Group 3, skin allograft and injection of ranibizumab (vascular endothelial growth factor antibody). A skin graft was performed 2 weeks before corneal transplantation. On days 3, 7, 11, and 14 after transplantation, the grafts were scored. The number of corneas with graft rejection on day 14 was significantly higher in Group 2 than in Group 1 or 3 (6/15 [40.0%] in Group 1, 13/15 [86.7%] in Group 2, and 4/15 [26.7%] in Group 3). The mean clinical scores for edema, opacity, and new vessels in Group 3 were significantly lower than those in Group 2, while the edema score in Group 1 was significantly lower than that in Group 2 on day 14. Before corneal allotransplantation, presensitization by skin grafting accelerated the graft rejection process. In a short-term presensitized rat model of keratoplasty, application of subconjunctival ranibizumab prevented graft rejection.

Prevention of VEGF-induced growth and tube formation in human retinal endothelial cells by aldose reductase inhibition

OBJECTIVE

Since diabetes-induced vascular endothelial growth factor (VEGF) is implicated in retinal angiogenesis, we aimed to examine the role of aldose reductase (AR) in VEGF-induced human retinal endothelial cells (HREC) growth and tube formation.

MATERIALS AND METHODS

HRECs were stimulated with VEGF and cell-growth was determined by MTT assay. AR inhibitor, fidarestat, to block the enzyme activity and AR siRNA to ablate AR gene expression in HREC were used to investigate the role of AR in neovascularization using cell-migration and tube formation assays. Various signaling intermediates and angiogenesis markers were assessed by Western blot analysis. Immuno-histochemical analysis of diabetic rat eyes was performed to examine VEGF expression in the retinal layer.

RESULTS

Stimulation of primary HREC with VEGF caused increased cell growth and migration, and AR inhibition with fidarestat or ablation with siRNA significantly prevented it. VEGF-induced tube formation in HREC was also significantly prevented by fidarestat. Treatment of HREC with VEGF also increased the expression of VCAM, AR, and phosphorylation and activation of Akt and p38-MAP kinase, which were prevented by fidarestat. VEGF-induced expression of VEGFRII in HREC was also prevented by AR inhibition or ablation.

CONCLUSIONS

Our results indicate that inhibition of AR in HREC prevents tube formation by inhibiting the VEGF-induced activation of the Akt and p38-MAPK pathway and suggest a mediatory role of AR in ocular neovascularization generally implicated in retinopathy and AMD.

Aflibercept: a Potent Vascular Endothelial Growth Factor Antagonist for Neovascular Age-Related Macular Degeneration and Other Retinal Vascular Diseases

Introduction

In the western hemisphere, age-related macular degeneration (AMD) is the leading cause of visual loss in the elderly. Currently approved therapies for AMD include argon laser, photodynamic therapy, and antivascular endothelial growth factor (VEGF) therapy. The index review discusses aflibercept (VEGF Trap-Eye) in the context of current anti-VEGF therapies for neovascular AMD and other retinal vascular diseases. It highlights important differences between VEGF Trap-Eye and currently used anti-VEGF therapies for neovascular AMD; and discusses the efficacy of these treatments utilizing information from landmark clinical trials.

Methods

A systematic search of literature was conducted on PubMed, Science Direct, and Scopus with no limitations of language or years of publication.

Results

Preclinical studies have shown that VEGF Trap-Eye binds to VEGF-A with a higher affinity than other anti-VEGF molecules; and that it also binds to placental growth factor (PlGF). In clinical trials, VEGF Trap-Eye has been shown to be as effective in the treatment of neovascular AMD as other anti-VEGF therapies and possibly to have a longer duration of drug activity.

Conclusion

VEGF Trap-Eye has enhanced the treatment options currently available for the management of neovascular AMD. The comparable efficacy of VEGF Trap-Eye (to other anti-VEGF agents) coupled with its longer dosing interval may decrease the number of annual office visits for patients with AMD and their caregivers.

Comparison of the effect between pegaptanib and ranibizumab on exudative age-related macular degeneration with small lesion size

PURPOSE

To compare the effect of pegaptanib versus ranibizumab on exudative age-related macular degeneration (AMD) with small lesion size.

METHODS

This is a retrospective study of 81 eyes from 78 patients with exudative AMD treated and followed up over 12 months. Patients with baseline best corrected visual acuity (BCVA) under 20/400 and with a greatest linear dimension of lesion over 4500 μm were excluded from the study. Twenty-six eyes from 25 patients were treated with three consecutive intravitreal injections of pegaptanib (IVP group) and 55 eyes from 54 patients were treated with three consecutive ranibizumab injections (IVR group). Each therapy was repeated as needed. The alteration in BCVA was evaluated in the IVP and IVR groups.

RESULTS

No differences were detected in baseline parameters between the IVP and IVR groups. The mean BCVA (logMAR) at month 1, 3, 6 and 12 after the initial treatment was improved from baseline in the IVP group (-0.095, -0.17, -0.18 and -0.18, respectively) and in the IVR group (-0.077, -0.15, -0.17 and -0.11, respectively), which was statistically significant. There was no difference in the change in mean BCVA between IVP and IVR groups at the same time periods.

CONCLUSIONS

The visual outcome of IVP was equivalent with IVR in exudative AMD with small lesion size.

EXTEND III: efficacy and safety of ranibizumab in South Korean and Taiwanese patients with subfoveal CNV secondary to AMD

BACKGROUND

The purpose of this study was to investigate the efficacy and safety of intravitreal ranibizumab 0.5 mg in South Korean and Taiwanese patients with subfoveal choroidal neovascularization (CNV) secondary to age-related macular degeneration (AMD).

METHODS

This was a 12-month, open-label, single-arm, multi-center, phase III study. Ninety-five patients (Taiwanese: 51; South Korean: 44) were included in the study. Key outcome measures assessed included: mean change in best-corrected visual acuity (BCVA) from baseline to months 4 (primary endpoint) and 12 (secondary endpoint); other secondary endpoints comprising categorized mean change in BCVA from baseline at month 4 and month 12, mean change in BCVA from baseline at month 4 and month 12 per baseline characteristics; and incidence of ocular and non-ocular adverse events and serious adverse events (SAEs) at month 12.

RESULTS

The mean BCVA change improved significantly (p < 0.0001) from baseline to both month 4 (+9.3 letters) and month 12 (+10.1 letters). At month 12, the proportion of patients who gained ≥5, 10, or 15 letters from baseline was 75.8%, 54.7%, and 32.6% respectively. Total and CNV lesion area significantly decreased from baseline (p < 0.0001). About 57% of patients showed complete absence of fluorescein leakage at month 12. Mean change from baseline visual acuity scores also increased significantly over time for all subgroups. At month 12, ocular SAEs occurred in 2.1% of patients (out of which one patient [1.1%] experienced endophthalmitis) and 16.8% of patients experienced non-ocular SAEs. There were no deaths reported during the study.

CONCLUSIONS

Consistent with previous studies in Caucasian and Japanese populations, EXTEND III confirms that monthly intravitreal injections of ranibizumab 0.5 mg administered over 12 months is effective and well-tolerated in South Korean and Taiwanese patients with subfoveal CNV secondary to AMD.

The impact of subconjuctivally injected EGF and VEGF inhibitors on experimental corneal neovascularization in rat model

AIM AND SCOPE

To investigate the inhibitory effect of subconjunctival application of VEGF antibodies bevacizumab, ranibizumab, pegaptanib, and HER2 antibody trastuzumab on corneal neovascularization in a rat model of experimental corneal neovascularization.

MATERIAL AND METHOD

Thirty male Wistar albino rats were included in the study. A chemical burn was induced in central cornea of one eye of the rats by a 75% silver nitrate and 25% potassium nitrate stick. Rats were randomly divided into five groups so that each group contained 6 subjects. Right after the chemical burn, 0.1 ml serum physiologic was injected subconjuctivally in control group (group 1). 1.25 mg/0.05 ml bevacizumab was injected in group 2; 1.2 mg/0.1 ml trastuzumab was injected in group 3; 0.5 mg/0.05 ml ranibizumab was injected in group-4; and 0.3 mg/0.1 ml pegaptanib was injected in group 5. On the 8th day of the experiment, rat corneas were photographed by digital photo-camera. Later, eyes of the sacrificed rats were enucleated and corneal speciements were histopathologically analyzed. The percentages of neovascularization on corneal photographs were examined with digital image analysis.

RESULTS

The percentage of corneal neovascularization in all treatment groups was found to be significantly lower than the control group (p < 0.05). Bevacizumab was found to be more effective than all other agents (p < 0.05). While the degree of inflammation and vascularization in bevacizumab and trastuzumab groups were significantly lower than the control group (p < 0.05), the difference was not significant in ranibizumab and pegaptanib groups (p > 0.05). In all treatment groups, fibroblast intensity was significantly lower than the control group. In terms of corneal thickness, no significant difference was observed between treatment and control groups (p > 0.05).

CONCLUSION

Bevacizumab, ranibizumab, pegaptanib, and trastuzumab were found effective for the inhibition of corneal NV. In our study we detected that the most effective agent was bevacizumab.

Effects of bevacizumab on the neovascular membrane of proliferative diabetic retinopathy: reduction of endothelial cells and expressions of VEGF and HIF-1α

PURPOSE

Anti-vascular endothelial growth factor (VEGF) agents have recently been used intravitreally during the perioperative period for proliferative diabetic retinopathy (PDR). However, the mechanism of theraputic effects of the agents remains unclear. This study aimed to investigate the effects of intravitreal bevacizumab (IVB) on retinal vascular endothelial cells and expressions of VEGF and hypoxia inducible factor-1α (HIF-1α) in PDR.

METHODS

Twenty-four patients with PDR were enrolled and randomized to two groups. Twelve eyes of 12 patients of each group received either an intravitreal injection of 1.25 mg bevacizumab or a sham injection 6 days before vitrectomy. Neovascular membranes (NVMs) were collected during pars plana vitrectomy. The numbers of vascular endothelial cells in the NVMs were counted after staining with hematoxylin and eosin and von Willebrand. The expressions of VEGF and HIF-1α in the NVMs were detected through immunohistochemistry. Ten epiretinal membrane specimens from patients with proliferative vitreoretinopathy (PVR) without IVB treatment were set as an additional control.

RESULTS

The number of vascular endothelial cells in NVMs of the IVB pretreated group was significantly lower than that of the sham group (21.5±3.94 versus 41.33±7.44, p=0.003). The IVB pretreated group also showed significantly lower levels of VEGF and HIF-1α in NVMs than those of the sham group (P(HIF-1α)=0.02, P(VEGF)<0.001). A stepwise regression analysis showed that IVB was a significant negative predictor for the numbers of vascular endothelial cells (β=-0.89, p<0.001) and the expressions of VEGF (β=-0.85, p<0.001) and HIF-1α (β=-0.64, p=0.001) in PDR patients. Epiretinal membranes of the PVR group showed negative staining of VEGF and HIF-1α.

CONCLUSIONS

Pretreatment with IVB in patients with PDR significantly decreased vascular endothelial cells and expressions of VEGF and HIF-1α, which further supports preoperative use of IVB in such patients.

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.

Does ranibizumab (Lucentis®) change retrobulbar blood flow in patients with neovascular age-related macular degeneration?

PURPOSE

To investigate the effects of intravitreal ranibizumab on retrobulbar blood flow in patients with neovascular age-related macular degeneration (AMD).

METHODS

Thirty-one eyes of 30 patients with neovascular AMD were examined prospectively by both color Doppler imaging and fundus fluorescein angiography. Color Doppler imaging was used to measure the maximum and minimum velocities of the central retinal vein, peak systolic/end-diastolic velocities of blood flows, and pulsatility index and resistivity index values in the central retinal artery, nasal/temporal posterior ciliary arteries (NPCA/TPCA) and ophthalmic artery. The t test for paired samples was used for comparing retrobulbar blood flow values before and after intravitreal ranibizumab (Lucentis®) injection in the study and control groups.

RESULTS

There was a statistically significant (p < 0.05) difference between the pre-injection and post-injection end-diastolic velocities of the NPCA and TPCA and resistivity index values of TPCA. The other parameters showed no statistically significant difference.

CONCLUSION

Our results show that intravitreal ranibizumab injection increases retrobulbar blood flow.

Comparison of choroidal and retinal endothelial cells: characteristics and response to VEGF isoforms and anti-VEGF treatments

Neovascular eye diseases such as wet age-related macular degeneration and proliferative diabetic retinopathy are two of the most common causes of irreversible visual loss. Although mediated by vascular endothelial growth factor (VEGF), the mechanisms of these diseases are not fully understood. Molecular inhibitors of VEGF including pegaptanib, ranibizumab and bevacizumab are used as treatments for these diseases. However, there have been very few direct comparisons between these agents, and as dose and treatment regimes differ their relative efficacies are hard to determine. In vitro comparisons tend to use cells from different sites or species, which show heterogeneity in their responses. The aim of this study was to compare the characteristics of primary cultures of isolated human choroidal endothelial cells (hCEC) and retinal endothelial cells (hREC), and their proliferation responses to stimulation with VEGF 121 and 165, and to compare the anti-proliferative effects of these three drugs. hCEC and hREC were positive for the cell markers VEGFR1, VEGFR2, CD31, CD34 and von Willebrand's factor (vWF), with greater expression of CD34 on the hREC compared to hCEC. Contrary to previous assumptions VEGF isoforms 121 and 165 were found to be equally potent in stimulating endothelial cell proliferation. However, hREC exhibited higher proliferation with either VEGF isoform compared to hCEC. The anti-VEGF treatments ranibizumab and bevacizumab were effective in decreasing proliferation of hCEC induced by the two VEGF isoforms, individually and in combination, with ranibizumab being moderately more effective, particularly in hREC. Pegaptanib was effective in controlling the proliferation of hCEC stimulated by VEGF 165, but was ineffective against the stimulatory effect of VEGF 121. There were found to be significant differences in microvascular endothelial cells from the retina and choroid, both in the expression of cell markers and their behaviour in response to growth factors and currently available anti-VEGF agents, highlighting the importance of targeting treatments to specific intraocular vascular beds and/or diseases.

Primary endpoint results of a phase II study of vascular endothelial growth factor trap-eye in wet age-related macular degeneration

OBJECTIVE

To evaluate the biologic effects and safety of vascular endothelial growth factor (VEGF) Trap-Eye during a 12-week fixed-dosing period in patients with neovascular (wet) age-related macular degeneration (AMD).

DESIGN

Multicenter, prospective, randomized, double-masked clinical trial with initial 12-week fixed dosing period. Data were analyzed to week 16.

PARTICIPANTS

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

METHODS

Patients were randomized 1:1:1:1:1 to VEGF Trap-Eye during the fixed-dosing phase (day 1 to week 12): 0.5 or 2 mg every 4 weeks (0.5 mg q4wk, 2 mg q4wk) on day 1 and at weeks 4, 8, and 12; or 0.5, 2, or 4 mg every 12 weeks (0.5 mg q12wk, 2 mg q12wk, or 4 mg q12wk) on day 1 and at week 12.

MAIN OUTCOME MEASURES

The primary endpoint was change from baseline in central retinal/lesion thickness (CR/LT) at week 12; secondary outcomes included change in best-corrected visual acuity (BCVA), proportion of patients with a gain of ≥ 15 letters, proportion of patients with a loss of >15 letters, and safety.

RESULTS

At week 12, treatment with VEGF Trap-Eye resulted in a significant mean decrease in CR/LT of 119 μm from baseline in all groups combined (P<0.0001). The reduction in CR/LT with the 2 mg q4wk and 0.5mg q4wk regimens was significantly greater than each of the quarterly dosing regimens. The BCVA increased significantly by a mean of 5.7 letters at 12 weeks in the combined group (P<0.0001), with the greatest mean gain of >8 letters in the monthly dosing groups. At 8 weeks, BCVA improvements were similar with 2 mg q4wk and 2 mg q12wk dosing. After the last required dose at week 12, CR/LT and visual acuity were maintained or further improved at week 16 in all treatment groups. Ocular adverse events were mild and consistent with safety profiles reported for other intraocular anti-VEGF treatments.

CONCLUSIONS

Repeated monthly intravitreal dosing of VEGF Trap-Eye over 12 weeks demonstrated significant reductions in retinal thickness and improvements in visual acuity, and was well-tolerated in patients with neovascular AMD.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Impact of Intravitreal Injection of Bevacizumab (Avastin) on Rabbit's Choroid and Retina

Aim:

The aim of the study was to evaluate the impact of intravitreal injection of bevacizumab (Avastin) on chorio-capillaris permeability as well as structure changes in the choroid and the retina of pigmented rabbits.

Material and Methods:

The study included 10 pigmented rabbits (20 clinically free eyes) ranged in weight between 1.2 and 2 kg (mean 1.7±0.05). The rabbits were subjected to intravitreal injection of 5 mg, 0.1mg Avastin in the right eyes (10eyes), while the left eyes (10eyes) were injected with equal volumes of balanced salt solution. 1 week later, Clinical examination and fundus fluorescein angiography (FFA) were done. Histological examination was performed on specimens of retina & choroid of Avastin & BSS injected eyes of sacrificed rabbits using light microscopy (LM) & transmission electron microscopy (TEM). Results were recorded and compared

Results:

Post injection clinical examination of the eyes showed no abnormality of cornea, lens, vitreous and fundus. FFA showed remarkable decrease in background chorio-capillaris fluorescence in 7 eyes (70 percent) injected with Avastin as compared with eyes injected with BSS. No change was observed in regards to retinal vasculature, or abnormal dye leak. LM examination: specimens from Avastin group were evaluated in comparison to control eyes Treated eyes exhibited the same microscopic appearance in most specimens (8/10, 80 percent). The chorio-capillaris layer showed elongated, stretched monolayer of capillaries with flat, elongated endothelial cell lining. The laminae showed closely packed RBCs arranged in a monolayer with ribbon like shape. The surrounding interstitial tissue showed stretched, elongated & compact collagen fibers. The RPE cells were tightly adherent to each other with prominent nuclei. The different retinal layers were in concomitance with the control specimens, however mild to moderate disruption of photoreceptor outer segments together with mild vacuolization in the ganglion cell layer were seen. TEM examination of both control and treated specimens confirmed the findings recorded by LM. The endothelial cell limning of the choriocapillaris exhibited reduced fenestrations in between the cells. TEM also highlighted the compact lamellae of collagen fibers. The RPE cells showed remarkable increase in the number of mitochondria and prominent endoplasmic reticulum. Variable sized melanosomes were also seen

Conclusion:

Though single intravitreal injection of Avastin does not cause appreciable histological changes in rabbit retina and choroid, yet, it imposes definite effect on choriocapillaris permeability as evidenced by FFA and ultra structural changes. Repeated intravitreal injections might alter the hemostasis of the chorio-capillaris RPE complex.

Diabetic retinopathy: pathogenic mechanisms and current treatments

Since diabetes is now a global epidemic, the incidence of retinopathy, a leading cause of blindness in patients aged 20-74 years, is also expected to rise to alarming levels. The risk of development and progression of diabetic retinopathy is closely associated with the type and duration of diabetes, blood glucose, blood pressure and possibly lipids. It is an unmet medical need that can lead to severe and irreversible loss of vision in people of working age worldwide. The aim of this review is to give an overview of the clinical and anatomical changes during the progression of retinopathy, the underlying pathogenic mechanisms that link hyperglycemia with retinal tissue damage, current treatments, and the emerging pharmacological therapies for this sight-threatening complication of diabetes.

[Immediate changes in intraocular pressure after an intravitreal injection of 2.5 mg of bevacizumab]

PURPOSE

To report the immediate changes of intraocular (IOP) pressure after an intravitreal injection of 2.5mg (0.1 ml) of bevacizumab.

METHODS

Prospective, non-controlled, interventional case series of 45 patients undergoing intravitreal injection of 2.5mg (0.1 mL) of bevacizumab for a variety of retinal disorders. IOP was measured with a Goldmann tonometer at baseline, immediately after, 30 minutes and one day after injection in all of the cases. The main outcome measured was the IOP immediately after injection.

RESULTS

At baseline the mean IOP was 16.6±2.8mm Hg (range, 10-24 mm Hg; median, 16 mm Hg; 25(th) percentile, 14 mm Hg and 75(th) percentile, 18 mm Hg). IOP rose to 53.9±18.2mm Hg (range, 16-78 mm Hg, median, 54 mm Hg; 25(th) percentile, 40 mm Hg and 75(th) percentile, 70 mm Hg; p<0.001) immediately after the injection. After 30 minutes, the IOP normalized but was still higher than baseline with a mean of 19.8±5.2 mm Hg (range, 10-36 mm Hg; median,18 mm Hg; 25(th) percentile,16 mm Hg and 75(th) percentile, 24 mm Hg; P<.01). At 24 hours the IOP was 15.7±3.1 mm Hg (range,10-24 mm Hg; median, 16 mm Hg; 25(th) percentile,14 mm Hg and 75(th) percentile,18 mm Hg; p>0.05).

CONCLUSIONS

An intravitreal injection of 2.5mg (0.1 ml) of bevacizumab causes a transient elevation of IOP that tends to return to normal 30 minutes later.

Enhanced differentiation of retinal progenitor cells using microfabricated topographical cues

Due to the retina’s inability to replace photoreceptors lost during retinal degeneration, significant interest has been placed in methods to implant replacement cells. Polymer scaffolds are increasingly being studied as vehicles for cellular delivery to degenerated retinas. Previously, we fabricated poly(methyl methacrylate) thin film scaffolds that increased survival and integration of implanted retinal progenitor cells (RPCs). Additionally, these scaffolds minimized the trauma and cellular response associated with implantation of foreign bodies into mouse eyes. Here, we demonstrate that biodegradable polycaprolactone (PCL) thin film scaffolds can be fabricated with integrated microtopography. Microfabricated topography in a PCL thin film enhanced the attachment and organization of RPCs compared to unstructured surfaces. Using real-time quantitative polymerase chain reaction we also observed that attachment to microtopography induced cellular differentiation. RPCs grown on PCL thin films exhibited an increase in gene expression for the photoreceptor markers recoverin and rhodopsin, an increase in the glial and Müller cell marker GFAP, and a decrease in SOX2 gene expression (a marker for undifferentiated progenitor cells) compared to cells grown on unmodified tissue culture polystyrene (TCPS).

Ghost cell glaucoma after intravitreal bevacizumab for postoperative vitreous hemorrhage following vitrectomy for proliferative diabetic retinopathy

BACKGROUND AND OBJECTIVE

To report the occurrence of ghost cell glaucoma after intravitreal injection of bevacizumab for the treatment of postoperative vitreous hemorrhage after vitrectomy for proliferative diabetic retinopathy (PDR).

PATIENTS AND METHODS

Retrospective chart review from August 2006 to December 2007. Patients who had postoperative vitreous hemorrhage after vitrectomy for PDR and received an intravitreal injection of bevacizumab were enrolled in the study.

RESULTS

Eight eyes of 8 patients (mean age: 46 years) were included. After intravitreal injection of bevacizumab, 4 (50%) eyes had clearance of vitreous hemorrhage. Three eyes developed ghost cell glaucoma within 1 week after intravitreal injection of bevacizumab. Of these, intraocular pressure was controlled in 1 eye through the use of anti-glaucoma medication, whereas the other 2 eyes needed surgical intervention to lower intraocular pressure and subsequently clear the vitreous hemorrhage.

CONCLUSION

Intravitreal injection of bevacizumab may accelerate the clearance of postoperative vitreous hemorrhage in cases of PDR. However, a high incidence of ghost cell glaucoma was observed. Caution should be exercised when administering an intravitreal injection of bevacizumab for a postoperative vitreous hemorrhage after vitrectomy for PDR.

Pegaptanib Sodium versus Pegaptanib Sodium Combined with Macular Laser Photocoagulation or Laser Alone for Diabetic Macular Edema

Purpose. To report the outcomes after primary intravitreal pegaptanib sodium in patients with diabetic macular edema (DME). Methods. We conduced a retrospective analysis of eyes with DME treated with primary intravitreal pegaptanib sodium (Macugen) (intravitreal pegaptanib group). The results were compared with the ones of eyes treated with intravitreal pegaptanib sodium associated with macular laser photocoagulation (combined treatment group), and the ones of eyes treated with primary macular laser photocoagulation (macular laser photocoagulation group). Results. For the intravitreal pegaptanib group (13 eyes), we found significant changes in mean best-corrected visual acuity (BCVA) and reductions in mean central macular thickness (CMT) at the last follow-up visit (P = .0014 and P = .0001). For the macular laser photocoagulation group (15 eyes), we found no statistically significant changes in mean BCVA and CMT at the last follow-up visit (P > .05). For the combined treatment group (12 eyes), we found no significant changes in mean BCVA at the last follow-up visit (P > .05) despite significant reductions in mean CMT (P = .0188). Conclusion. Intravitreal pegaptanib treatment alone may be superior to macular laser photocoagulation alone and to combined intravitreal pegaptanib treatment associated with macular laser photocoagulation in patients with DME.

Clinical safety of ranibizumab in age-related macular degeneration

IMPORTANCE OF THE FIELD

Clinical safety of pharmaceutical products in the elderly is vital because of their increased risk of cardiac and other adverse events.

AREAS COVERED IN THIS REVIEW

Search of the Medline database, including articles and abstracts from 1984 to 2009.

WHAT THE READER WILL GAIN

Knowledge of ocular and systemic risks: The rate of endophthalmitis was 0.05% per injection (MARINA) and <0.1% per injection (ANCHOR), rates confirmed in a retrospective analysis of 14,320 injections. Moderate increases in intraocular pressure were transient, and incidences of intraocular inflammation were rarely serious. Systemic arterial thromboembolic events occurred in 4.6 and 0% of ranibizumab-treated patients and in 3.8 and 0% of sham-treated patients in MARINA (2 years) and PIER (1 year), respectively. In SAILOR, there was a numerically higher rate of cerebrovascular stroke with 0.5 mg ranibizumab compared with 0.3 mg ranibizumab (1.2 vs 0.7%), which was a non-statistically significant trend in patients with a history of stroke.

TAKE HOME MESSAGE

Although further studies to investigate the risk of stroke with ranibizumab therapy are required, repeated intravitreal ranibizumab was well tolerated and not associated with clinically significant safety risks during up to 2 years of treatment.

[Surgical session: neovascular glaucoma and anti-vascular endothelial growth factor treatment]

Recent research has shown the key role of vascular endothelial growth factor (VEGF), mainly one of its isoform, VEGF-A, in ocular pathologies involving neovascularization. New intraocular treatments targeting specifically VEGF (anti-VEGF) has been developed. These agents have revolutionized the treatment and visual prognosis of neovascular agerelated macular degeneration (AMD). Their potential for other ocular diseases, such as neovascular glaucoma, is currently under clinical investigations. We briefly review the current knowledge and clinical data, and present our clinical experience with the use of intravitreal bevacizumab in neovascular glaucoma.

Evaluation of safety for bilateral same-day intravitreal injections of antivascular endothelial growth factor therapy

PURPOSE

To explore the incidence of complications after bilateral same-day intravitreal injections of antivascular endothelial growth factor pharmacotherapies in this retrospective interventional case series.

METHODS

An electronic review of billing records was performed to identify all bilateral same-day intravitreal antivascular endothelial growth factor injections performed within a single group retina practice between January 6, 2006 and June 1, 2009. The charts were reviewed to identify the complications of endophthalmitis, intraocular inflammation, retinal tear, and retinal detachment.

RESULTS

A total of 1,534 bilateral intravitreal injections (326 bevacizumab and 1,208 ranibizumab: 3,068 injections total) were performed in 367 patients. Three complications were identified. Two cases of unilateral culture-proven endophthalmitis occurred after bilateral intravitreal ranibizumab, and one case of unilateral acute intraocular inflammation occurred after bilateral intravitreal bevacizumab. In all three of these eyes, visual acuity returned to its preinjection level. No cases of retinal tear or retinal detachment were identified. The incidence of culture-proven endophthalmitis was 0.065%, and the incidence of acute intraocular inflammation was 0.033%.

CONCLUSION

The complication rates after bilateral same-day intravitreal antivascular endothelial growth factor injections seem to be similar to those after unilateral injections. Severe acute intraocular inflammation can occur unilaterally after same-day bilateral injections of bevacizumab.

alphaB-crystallin regulation of angiogenesis by modulation of VEGF

alphaB-crystallin is a chaperone belonging to the small heat shock protein family. Herein we show attenuation of intraocular angiogenesis in alphaB-crystallin knockout (alphaB-crystallin(-/-)) mice in 2 models of intraocular disease: oxygen-induced retinopathy and laser-induced choroidal neovascularization. Vascular endothelial growth factor A (VEGF-A) mRNA and hypoxia inducible factor-1alpha protein expression were induced during retinal angiogenesis, but VEGF-A protein expression remained low in alphaB-crystallin(-/-) retina versus wild-type mice, whereas VEGF-R2 expression was not affected. Both alphaB-crystallin and its phosphorylated serine59 formwere expressed, and immunoprecipitation revealed alphaB-crystallin binding to VEGF-A but not transforming growth factor-beta in cultured retinal pigment epithelial (RPE) cells. alphaB-crystallin and VEGF-A are colocalized in the endoplasmic reticulum in RPE cells under chemical hypoxia. alphaB-crystallin(-/-) RPE showed low VEGF-A secretion under serum-starved conditions compared with wild-type cells. VEGF-A is polyubiquitinated in control and alphaB-crystallin siRNA treated RPE; however, mono-tetra ubiquitinated VEGF-A increases with alphaB-crystallin knockdown. Endothelial cell apoptosis in newly formed vessels was greater in alphaB-crystallin(-/-) than wild-type mice. Proteasomal inhibition in alphaB-crystallin(-/-) mice partially restores VEGF-A secretion and angiogenic phenotype in choroidal neovascularization. Our studies indicate an important role for alphaB-crystallin as a chaperone for VEGF-A in angiogenesis and its potential as a therapeutic target.

The Ahmed glaucoma valve in neovascular glaucoma (An AOS Thesis)

PURPOSE

To evaluate the results of Ahmed glaucoma valve surgery in neovascular glaucoma and control patients.

METHODS

In this retrospective comparative study, we reviewed 76 eyes of 76 patients, comparing the surgical outcomes in control patients (N=38) to matched neovascular glaucoma patients (N=38). Success was defined as intraocular pressure (IOP) > or =6 mm Hg and < or =21 mm Hg, without further glaucoma surgery, and without loss of light perception.

RESULTS

Average follow-up for control and neovascular glaucoma patients was 18.4 and 17.4 months, respectively (P = .550). At last follow-up, mean IOP was 16.2 +/- 5.2 mm Hg and 15.5 +/- 12.5 mm Hg (P = .115) in control and neovascular glaucoma patients, respectively. Life-table analysis showed a significantly lower success for neovascular glaucoma patients compared with controls (P = .0096), with success at 1 year of 89.2% and 73.1%, at 2 years of 81.8% and 61.9%, and at 5 years of 81.8% and 20.6% for control and neovascular glaucoma eyes, respectively. Cox proportional hazards regression analysis showed neovascular glaucoma as a risk factor for surgical failure (odds ratio, 5.384, 95% CI, 1.22-23.84, P = .027). Although IOP control and complications were comparable between the two groups, visual outcomes were worse in neovascular glaucoma patients, with 9 eyes (23.7%) with neovascular glaucoma compared with no controls losing light perception vision (P = .002). The majority with loss of vision (5 of 9) had successful control of IOP during the postoperative period.

CONCLUSION

Neovascular glaucoma patients have greater risk of surgical failure after Ahmed glaucoma valve surgery compared with controls. Despite improved mean IOP with drainage implants, visual outcomes may be poor, possibly due to progression of underlying disease.

Intravitreal pegaptanib sodium (Macugen) for diabetic macular oedema

PURPOSE

To report the functional and anatomical outcomes resulting from the use of intravitreal pegaptanib sodium (Macugen) in patients with diabetic macular oedema (DMO).

METHODS

We conducted a retrospective outcome analysis, by optical coherence tomography (OCT) and best-corrected visual acuity (BCVA), of eyes with DMO treated with intravitreal pegaptanib sodium. Moreover, we evaluated the foveal transverse photoreceptor (PR) band integrity in the OCT images at the time of the last follow-up visit.

RESULTS

Sixty-three eyes of 48 patients with a minimum of 6 months of follow-up were included for analysis. Intravitreal pegaptanib was found to produce significant improvements in mean BCVA (p = 0.019) and reductions in mean central macular thickness (CMT) (p < 0.001) as soon as the 6-week follow-up. Most eyes (60/63) required a mean of 3.03 +/- 0.9 repeated treatments, over a mean follow-up period of 6.7 +/- 1.2 months, to achieve significant improvements in mean BCVA (p < 0.001) and mean CMT (p < 0.001). In our series, the lower visual acuities tended to congregate in the group with the less-defined PR band (p < 0.001) and the lower CMT tended to congregate in the group with the best-defined PR band (p = 0.04), even though the higher CMT did not tend to congregate in the group with the less-defined PR band.

CONCLUSION

Our findings demonstrate that selective inhibition by intravitreal pegaptanib sodium of vascular endothelial growth factor (VEGF)-165 may produce a clinically meaningful and statistically significant benefit in the treatment of DMO.

Cost-effectiveness of ranibizumab compared with pegaptanib in neovascular age-related macular degeneration

OBJECTIVE

To assess the cost-effectiveness of ranibizumab compared with pegaptanib in the treatment of patients with minimally classic/occult neovascular age-related macular degeneration (AMD), from a societal perspective in Spain.

METHODS

We constructed a Markov model with five states defined by visual acuity (VA) in the better-seeing eye (Snellen scale): VA >20/40, < or =20/40 to >20/80, < or =20/80 to >20/200, < or =20/200 to >20/400, < or =20/400, and an additional death state. Two cohorts of patients were distributed along the VA states, and treated with either ranibizumab or pegaptanib. Transition probabilities assigned for movement between these states with both drugs were obtained from published randomized clinical trials. Medical costs related to AMD treatment and follow-up, medical costs related to AMD comorbidities, and non-medical-related costs were taken into account. Costs (2008 Euro), health outcomes (Quality-adjusted life years--QALYs), both discounted at a 3.5% annual rate, and incremental cost-effectiveness ratios (ICER: euro/QALY), were determined for a lifetime horizon in the base case analysis. Sensitivity analyses were conducted to explore different scenarios and assumptions in the model.

RESULTS

Treating patients with varying degrees of visual impairment with monthly ranibizumab instead of pegaptanib was 71,206 euro more costly and provided 2.437 additional QALYs (29,224 euro/QALY). When administered on an as-needed basis, as in the Prospective Optical Coherence Tomography Imaging of Patients with Neovascular AMD Treated with Intraocular Ranibizumab (PrONTO) trial, the cost per QALY gained with ranibizumab was reduced to 4,623 euro.

CONCLUSIONS

The cost per QALY gained with monthly ranibizumab compared with pegaptanib in the minimally classic/occult neovascular AMD population is just below the 30,000 euro threshold below which new drugs are sometimes regarded as cost-effective strategies in Spain. In this model, the key variables with greater impact on the cost-effectiveness results were the selected time horizon and the chosen extrapolation method, the source for data on pegaptanib efficacy and the number of ranibizumab injections. When administered on an as-needed basis, ranibizumab was a cost-effective strategy compared to pegaptanib in this population.

Effect of multiple injections of small divided doses vs single injection of intravitreal bevacizumab on retinal neovascular model in rabbits

BACKGROUND

To compare effects of multiple injections of small divided doses of intravitreal bevacizumab vs a single injection using a retinal neovascular model in rabbits.

METHODS

We assigned 12 pigmented rabbits to four groups of three each. All groups received an intravitreal injection of vascular endothelial growth factor (VEGF, 10 microg) on the first day. Group A received an intravitreal loading dose of bevacizumab (0.5 mg) on day 3, followed by five smaller injections (0.15 mg), one every third day. Those in groups B and C received a single intravitreal injection of bevacizumab (1.25 mg) on day 3, followed by five injections of sham, one every third day in group C. Group D received only intravitreal VEGF. Follow-up examinations were performed for 26 days.

RESULTS

In groups A and B, vascular changes associated with VEGF injection decreased substantially in the first 3 days, and continued to show gradual regression during each follow-up interval. No statistically significant differences were found between the changes of mean retinal thicknesses in groups A and B in both areas. In group C, the extra sham injections did not lead to any further vascular changes. The mean retinal thickness in groups B and C did not have a statistically significant difference during the follow-up period. In group D, vascular changes resolved more gradually than in other groups. The difference in retinal thickness between group D and the other groups was statistically significant on day 6 in both groups (medullary and inferior part; p = 0.0003) and in medullary wing on day 12 (p = 0.03).

CONCLUSIONS

Frequent smaller doses of bevacizumab can control VEGF-induced vascular changes as well as the currently utilized model of single large monthly injections. Dividing of currently used single injection (1.25 mg) of bevacizumab to multiple small doses can control VEGF-induced vascular changes as effectively as one large injection.