Michael J. Tolentino

A Randomized Trial Comparing the Efficacy and Safety of Intravitreal Triamcinolone With Observation to Treat Vision Loss Associated With Macular Edema Secondary to Central Retinal Vein Occlusion: The Standard Care vs Corticosteroid for Retinal Vein Occlusion (SCORE) Study Report 5

OBJECTIVE To compare the efficacy and safety of 1-mg and 4-mg doses of preservative-free intravitreal triamcinolone with observation for eyes with vision loss associated with macular edema secondary to perfused central retinal vein occlusion (CRVO). METHODS Multicenter, randomized, clinical trial of 271 participants. MAIN OUTCOME MEASURE Gain in visual acuity letter score of 15 or more from baseline to month 12. RESULTS Seven percent, 27%, and 26% of participants achieved the primary outcome in the observation, 1-mg, and 4-mg groups, respectively. The odds of achieving the primary outcome were 5.0 times greater in the 1-mg group than the observation group (odds ratio [OR], 5.0; 95% confidence interval [CI], 1.8-14.1; P = .001) and 5.0 times greater in 4-mg group than the observation group (OR, 5.0; 95% CI, 1.8-14.4; P = .001); there was no difference identified between the 1-mg and 4-mg groups (OR, 1.0; 95% CI, 0.5-2.1; P = .97). The rates of elevated intraocular pressure and cataract were similar for the observation and 1-mg groups, but higher in the 4-mg group. CONCLUSIONS Intravitreal triamcinolone is superior to observation for treating vision loss associated with macular edema secondary to CRVO in patients who have characteristics similar to those in the SCORE-CRVO trial. The 1-mg dose has a safety profile superior to that of the 4-mg dose. Application to Clinical Practice Intravitreal triamcinolone in a 1-mg dose, following the retreatment criteria applied in the SCORE Study, should be considered for up to 1 year, and possibly 2 years, for patients with characteristics similar to those in the SCORE-CRVO trial. Trial Registration clinicaltrials.gov Identifier: NCT00105027.

INTRAVITREOUS INJECTIONS OF VASCULAR ENDOTHELIAL GROWTH FACTOR PRODUCE RETINAL ISCHEMIA AND MICROANGIOPATHY IN AN ADULT PRIMATE

PURPOSE The purpose of the study is to determine the effect of exogenous vascular endothelial growth factor (VEGF) on the primate retina and its vasculature. METHODS Ten eyes of five animals were studied. Physiologically relevant amounts of the 165 amino acid isoform of human recombinant VEGF were injected into the vitreous of six healthy cynomolgus monkey eyes. Inactivated human recombinant VEGF or vehicle was injected into four contralateral control subject eyes. Eyes were assessed by slit-lamp biomicroscopy, tonometry, fundus color photography, fundus fluorescein angiography, light microscopy, and immunostaining with antibodies against proliferating cell nuclear antigen and factor VIII antigen. RESULTS All six bioactive VEGF-injected eyes developed dilated, tortuous retinal vessels that leaked fluorescein. Eyes receiving multiple injections of VEGF developed progressively dilated and tortuous vessels, venous beading, edema, microaneurysms, intraretinal hemorrhages and capillary closure with ischemia. The severity of the retinopathy correlated with the number of VEGF injections. None of the four control eyes exhibited any abnormal retinal vascular changes. The endothelial cells of retinal blood vessels were proliferating cell nuclear antigen positive only in the bioactive VEGF-injected eyes. CONCLUSION Vascular endothelial growth factor is sufficient to produce many of the vascular abnormalities common to diabetic retinopathy and other ischemic retinopathies, such as hemorrhage, edema, venous beading, capillary occlusion with ischemia, microaneurysm formation, and intraretinal vascular proliferation.

REACTIVE OXYGEN INTERMEDIATES INCREASE VASCULAR ENDOTHELIAL GROWTH FACTOR EXPRESSION IN VITRO AND IN VIVO

Elevated vascular endothelial growth factor (VEGF) levels are required for ocular and tumor angiogenesis in animal models. Ischemic hypoxia is strongly correlated with increased VEGF expression in these systems and is considered a physiologically relevant stimulus. Because ischemic hypoxia is often followed by reperfusion and reactive oxygen intermediate (ROI) generation, we examined the potential role of ROI in the control of VEGF gene expression. Human retinal pigment epithelial cells exposed to superoxide or hydrogen peroxide rapidly increased VEGF mRNA levels. Superoxide-associated mRNA increases were dose dependent, blocked by antioxidants, and associated with elevated VEGF protein levels in conditioned media. Increases in VEGF mRNA levels were also observed in cultured human melanoma and rat glioblastoma cells with superoxide or hydrogen peroxide. Cycloheximide prevented the ROI-associated increases in VEGF mRNA. Transcriptional inhibition with actinomycin D revealed an inducible increase in VEGF mRNA half-life, but nuclear run-on experiments showed no increase in VEGF transcriptional rate. Reoxygenation of human retinal pigment epithelial cells in vitro and ocular reperfusion in vivo increased retinal VEGF mRNA levels. Antioxidants prevented the reperfusion-associated VEGF mRNA increases in retina. We conclude that ROIs increase VEGF gene expression in vitro and during the reperfusion of ischemic retina in vivo. The ROI-associated increases are mediated largely through increases in VEGF mRNA stability.

Advanced glycation end products increase retinal vascular endothelial growth factor expression.

Advanced glycation end products (AGEs) are linked with the development of diabetic retinopathy; however, the pathogenic mechanisms are poorly defined. Vascular endothelial growth factor (VEGF) levels are increased in ischemic and nonischemic diabetic retina, and VEGF is required for the development of retinal and iris neovascularization. Moreover, VEGF alone can induce much of the concomitant pathology of diabetic retinopathy. In this study, we found that AGEs increased VEGF mRNA levels in the ganglion, inner nuclear, and retinal pigment epithelial (RPE) cell layers of the rat retina. In vitro, AGEs increased VEGF mRNA and secreted protein in human RPE and bovine vascular smooth muscle cells. The AGE-induced increases in VEGF expression were dose- and time-dependent, inhibited by antioxidants, and additive with hypoxia. Use of an anti-VEGF antibody blocked the capillary endothelial cell proliferation induced by the conditioned media of AGE-treated cells. AGEs may participate in the pathogenesis of diabetic retinopathy through their ability to increase retinal VEGF gene expression.

Pathologic features of vascular endothelial growth factor-induced retinopathy in the nonhuman primate

PURPOSE Vascular endothelial growth factor (VEGF) is a potent ischemia-upregulated angiogenic protein that has been implicated in diabetic retinopathy. Intravitreal VEGF injections have not previously been shown to produce preretinal neovascularization. The purpose of this study was to further characterize the angiopathic changes that occur after intravitreal injections in a nonhuman primate and determine if preretinal neovascularization develops. DESIGN Experimental animal study. METHODS Vascular endothelial growth factor 165 was injected into the eyes of normal cynomolgus monkeys at regular intervals. As a control, normal eyes were injected with phosphate buffered saline. Color photography and fluorescein angiography were performed at regular intervals. The retinas were incubated for adenosine diphosphatase (ADPase) activity to visualize retinal vessels. The retinas were flat-embedded and areas of potential preretinal neovascularization were identified en bloc and serially sectioned. RESULTS Areas of capillary nonperfusion and vessel dilation and tortuousity were seen by angiography. In serial sections, the nonperfused areas were found to be associated with endothelial cell hyperplasia in vessel lumens. Preretinal neovascularization originating only from superficial veins and venules was observed throughout peripheral retina, but was not seen in the posterior pole. Lacunae-like veins were subdivided by the process of intussusception and endothelial cell bridging. Arterioles demonstrated endothelial cell hyperplasia and microaneurysms. CONCLUSION Intraocular injections of VEGF were sufficient to produce preretinal neovascularization in the nonhuman primate. Most vasculopathic structures were associated with endothelial cell hyperplasia. These results demonstrate that VEGF alone can produce many features of both nonproliferative and proliferative diabetic retinopathy including the previously undescribed development of preretinal neovascularization. This well-characterized VEGF-induced primate model of retinal neovascularization may be useful as a means of testing new treatments for retinal neovascularization.

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

Purpose To determine the safety and efficacy of small interfering RNA (siRNA) directed against vascular endothelial growth factor (VEGF) in a nonhuman primate model of laser-induced choroidal neovascularization (CNV). Methods Each animal received laser rupture of Bruch’s membrane to induce CNV in both eyes. Each animal was then randomized to receive 0.05 mL of either vehicle alone or VEGF siRNA at 70 &mgr;g, 150 &mgr;g, or 350 &mgr;g in both eyes by intravitreal injection. Eyes were monitored weekly by ophthalmic examination, color photography, and fluorescein angiography for 36 days after laser injury. Electroretinograms were measured at baseline and at 5 weeks after laser. CNV on fluorescein angiograms were measured for area and graded for clinically significant leakage in a standardized, randomized, and double-masked fashion on days 15, 22, 29, and 36 after laser. Results VEGF siRNA did not cause any change in electroretinographic, hemorrhage, inflammation, or clinical signs of toxicity. A single administration of VEGF siRNA significantly inhibited growth of CNV and attenuated angiographic leakage in a dose-dependent manner. Conclusion Intravitreal injection of VEGF siRNA is capable of inhibiting the growth and vascular permeability of laser-induced CNV in a nonhuman primate in a dose-dependent manner. This study demonstrates preclinical proof of a principle that supports proceeding to clinical studies of VEGF siRNA in patients with exudative age-related macular degeneration.

Regulation of Vascular Endothelial Growth Factor Expression by Insulin-Like Growth Factor I

Insulin-like growth factor I (IGF-I) and vascular endothelial growth factor (VEGF) levels are correlated with retinal ischemia-associated intraocular neovascu-larization in humans. Since VEGF is required for iris and retinal neovascularization in animal models of retinal ischemia, we tested whether IGF-I could act as an indirect angiogenic factor by increasing VEGF gene expression. IGF-I increased retinal pigment epithelial (RPE) cell VEGF mRNA in a concentration-dependent manner with an EC50 of 7 nmol/l (53.6 ng/ml). RPE and bovine smooth muscle cells exposed to 50 nmol/1 (383 ng/ml) IGF-I achieved peak VEGF mRNA expression within 2 h. IGF-I-treated RPE cells increased VEGF protein levels in conditioned media and stimulated capillary endothelial cell proliferation. Blockade of the IGF-I receptor with a neutralizing antibody abrogated the VEGF increases in RPE cells. Further, hypoxia-mediated and IGF-I-mediated increases in VEGF mRNA and protein levels were additive in RPE cells, and the hypoxia-induced VEGF increases were independent of endogenous IGF-I. VEGF promoter activity was enhanced by IGF-I in RPE cells, but VEGF transcript half-life was unaltered. In summary, the supplementation of RPE and smooth muscle cell cultures with IGF-I at 5-100 nmol/1 increased VEGF mRNA and secreted protein levels. The VEGF increases in RPE cells occurred primarily through enhanced transcription of the VEGF gene and via the IGF-I receptor. Elevated IGF-I levels may promote neovascularization through increased retinal VEGF gene expression.

The DA VINCI Study: Phase 2 Primary Results of VEGF Trap-Eye in Patients with Diabetic Macular Edema

PURPOSE To determine whether different doses and dosing regimens of intravitreal vascular endothelial growth factor (VEGF) Trap-Eye are superior to focal/grid photocoagulation in eyes with diabetic macular edema (DME). DESIGN Multicenter, randomized, double-masked, phase 2 clinical trial. PARTICIPANTS A total of 221 diabetic patients with clinically significant macular edema involving the central macula. METHODS Patients were assigned to 1 of 5 treatment regimens: 0.5 mg VEGF Trap-Eye every 4 weeks; 2 mg VEGF Trap-Eye every 4 weeks; 2 mg VEGF Trap-Eye for 3 initial monthly doses and then every 8 weeks; 2 mg VEGF Trap-Eye for 3 initial monthly doses and then on an as-needed (PRN) basis; or macular laser photocoagulation. Assessments were completed at baseline and every 4 weeks thereafter. MAIN OUTCOME MEASURES Mean change in visual acuity and central retinal thickness (CRT) at 24 weeks. RESULTS Patients in the 4 VEGF Trap-Eye groups experienced mean visual acuity benefits ranging from +8.5 to +11.4 Early Treatment of Diabetic Retinopathy Study (ETDRS) letters versus only +2.5 letters in the laser group (P ≤ 0.0085 for each VEGF Trap-Eye group vs. laser). Gains from baseline of 0+, 10+, and 15+ letters were seen in up to 93%, 64%, and 34% of VEGF Trap-Eye groups versus up to 68%, 32%, and 21% in the laser group, respectively. Mean reductions in CRT in the 4 VEGF Trap-Eye groups ranged from -127.3 to -194.5 μm compared with only -67.9 μm in the laser group (P = 0.0066 for each VEGF Trap-Eye group vs. laser). VEGF Trap-Eye was generally well tolerated. Ocular adverse events in patients treated with VEGF Trap-Eye were generally consistent with those seen with other intravitreal anti-VEGF agents. CONCLUSIONS Intravitreal VEGF Trap-Eye produced a statistically significant and clinically relevant improvement in visual acuity when compared with macular laser photocoagulation in patients with DME.

Long-term Benefit of Sustained-Delivery Fluocinolone Acetonide Vitreous Inserts for Diabetic Macular Edema

OBJECTIVE To assess the efficacy and safety of intravitreal inserts releasing 0.2 μg/day (low dose) or 0.5 μg/day (high dose) fluocinolone acetonide (FA) in patients with diabetic macular edema (DME). DESIGN Two parallel, prospective, randomized, sham injection-controlled, double-masked, multicenter clinical trials. PARTICIPANTS Subjects with persistent DME despite at least 1 macular laser treatment were randomized 1:2:2 to sham injection (n = 185), low-dose insert (n = 375), or high-dose insert (n = 393). METHODS Subjects received study drug or sham injection at baseline and after 6 weeks were eligible for rescue laser. Based on retreatment criteria, additional study drug or sham injections could be given after 1 year. MAIN OUTCOME MEASURES The primary outcome was the percentage of patients with improvement from baseline best-corrected visual acuity (BCVA) in Early Treatment Diabetic Retinopathy Trial (ETDRS) letter score of 15 or more at month 24. Secondary outcomes included other parameters of visual function and foveal thickness (FTH). RESULTS The percentage of patients with improvement from baseline ETDRS letter score of 15 or more at month 24 was 28.7 and 28.6 in the low- and high-dose insert groups, respectively, compared with 16.2 in the sham group (P = 0.002 for each). Benefit occurred for both doses compared with sham at 3 weeks and all subsequent time points. The mean improvement in BCVA letter score between baseline and month 24 was 4.4 and 5.4 in the low- and high-dose groups, respectively, compared with 1.7 in the sham group (P = 0.02 and P = 0.016). At all time points compared with sham, there was significantly more improvement in FTH. Subjects requiring cataract surgery were more frequent in the insert groups, and their visual benefit was similar to that of subjects who were pseudophakic at baseline. Glaucoma requiring incisional surgery occurred in 3.7%, 7.6%, and 0.5% of the low-dose, high-dose, and sham groups, respectively. CONCLUSIONS Both low- and high-dose FA inserts significantly improved BCVA in patients with DME over 2 years, and the risk-to-benefit ratio was superior for the low-dose insert. This is the first pharmacologic treatment that can be administered by an outpatient injection to provide substantial benefit in patients with DME for at least 2 years.

Visual field deficits in early age-related macular degeneration

Patients with early age-related macular degeneration (AMD) may retain good visual acuity but experience distortion and other qualitative visual changes. The purpose of the present study was to determine whether deficits of form recognition, as well as of light sensitivity, were related to retinal pigment epithelial (RPE) atrophy and/or drusen. We assessed form recognition deficits by the Amsler grid and by a perimetric test of letter recognition and sensitivity deficits by the macular threshold test of the Humphrey Field Analyzer in 59 patients with AMD and visual acuities of 20/40 or better. The number of defects on each test was compared with the area of RPE atrophy and with the area of drusen determined from fundus photographs. Multiple regression analyses based on ordinal data revealed that the number of visual field defects by each test was significantly correlated with the area of atrophy, but not with the area of drusen. There was also no significant tendency for a patient with a regional preponderance of drusen to have more impairment in the corresponding visual field. These results suggest that deficits of form recognition, as well as of sensitivity, in patients with early stages of AMD can be attributed to alteration of photoreceptor function associated with RPE atrophy, but not with drusen.