Randomized Trial of Biosimilar XSB-001 versus Reference Ranibizumab in Patients with Neovascular Age-Related Macular Degeneration.

OBJECTIVE: To evaluate the efficacy, safety, and immunogenicity of a ranibizumab biosimilar candidate (XSB-001) versus reference product (Lucentis) for neovascular age-related macular degeneration (nAMD). DESIGN: Phase III, multicenter, randomized, double-masked, parallel-group study. PARTICIPANTS: Patients with nAMD. METHODS: Eligible patients were randomized (1:1) to receive intravitreal injections of XSB-001 or reference ranibizumab (0.5 mg [0.05 ml]) in the study eye once every 4 weeks for 52 weeks. Efficacy and safety assessments continued through 52 weeks of treatment. MAIN OUTCOME MEASURES: Primary end point was change from baseline in best-corrected visual acuity (BCVA) by ETDRS letters at week 8. Biosimilarity was concluded if the 2-sided 90% confidence interval (CI) (United States) or 95% CI (rest of world) for the difference in least-squares (LS) mean change in BCVA at week 8 between treatment groups was within the predefined equivalence margin of ± 3.5 letters. RESULTS: In total, 582 patients (n = 292 XSB-001, n = 290 reference ranibizumab) were randomized. Mean age was 74.1 years, most patients (85.2%) were White, and 55.8% were women. Mean BCVA score at baseline was 61.7 and 61.5 ETDRS letters in the XSB-001 and reference ranibizumab groups, respectively. At week 8, the LS mean (standard error [SE]) change in BCVA from baseline was 4.6 (0.5) ETDRS letters in the XSB-001 group and 6.4 (0.5) letters in the reference ranibizumab group (LS mean [SE] treatment difference: -1.8 [0.7] ETDRS letters; 90% CI, -2.9 to -0.7; 95% CI, -3.1 to -0.5). The 90% CI and 95% CI for LS mean difference in change from baseline were within the predefined equivalence margin. At week 52, LS mean (SE) change in BCVA was 6.4 (0.8) and 7.8 (0.8) letters, respectively (LS mean [SE] treatment difference, -1.5 [1.1] ETDRS letters; 90% CI, -3.3 to 0.4; 95% CI, -3.6 to 0.7). There were no clinically meaningful differences between treatments in anatomical, safety, or immunogenicity end points through week 52. CONCLUSIONS: XSB-001 demonstrated biosimilarity to reference ranibizumab in patients with nAMD. Treatment with XSB-001 for 52 weeks was generally safe and well tolerated, with a safety profile similar to the reference product. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Private equity ownership of ophthalmology practices: how does it impact clinical research?

PURPOSE OF REVIEW: To explore the impact of private equity ownership of ophthalmology practices on the success of their clinical research programs. RECENT FINDINGS: Private equity partnership in the clinical research space has been steadily occurring over the past decades. In addition to contract research organizations, private equity groups have also consolidated multiple independent clinical research networks. By investing in an increasing number of retina practices, one private equity group is attempting to create a synergistic relationship between clinical practice and clinical research with the goal of supporting a larger, more robust clinical research network. SUMMARY: Although there are physician concerns about the potential deleterious effects of private equity ownership on clinical research capabilities, private equity support has the potential to be an important stimulus for clinical research growth. VIDEO ABSTRACT: http://links.lww.com/COOP/A48.

Brolucizumab-associated intraocular inflammation in eyes without retinal vasculitis.

PURPOSE: To analyze a series of eyes with brolucizumab-associated intraocular inflammation (IOI) without retinal vasculitis reported to the American Society of Retina Specialists (ASRS). METHODS: The ASRS Research and Safety in Therapeutics (ReST) Committee analyzed clinical characteristics from submitted reports of IOI after brolucizumab. Eyes with retinal vasculitis or that received intraocular antibiotics were excluded. RESULTS: Forty-nine eyes of 45 patients were collected. Mean visual acuity (VA) at baseline was 20/49 (range 20/20 - 5/200). Patients presented with IOI a mean of 24 (range 3-63) days after most recent brolucizumab injection; 61% presented for an unscheduled visit while 39% presented at routine follow-up. Mean VA at IOI presentation was 20/67 (range 20/20 - 3/200). Most common symptoms were floaters (78%) and blurry vision (76%). Pain (20%) and redness (16%) were less common; 3 (6%) eyes were asymptomatic. IOI was anterior only in 18%, posterior only in 31%, and both anterior and posterior in 51% of eyes. Treatment included topical steroids alone in 67% eyes, while 10% eyes received no treatment. Mean VA at last follow-up was 20/56 (range 20/20 - 1/200). Three (6%) eyes lost 3 or more lines and 1 (2%) eye lost 6 or more lines. CONCLUSIONS: Brolucizumab-associated IOI without retinal vasculitis typically presented with a delayed onset of a few weeks. Often, visual acuity decline was relatively mild. Most symptoms resolved and nearly all had a return to baseline VA, but a small percentage of patients had a significant decrease in VA at last follow-up.

C5 Inhibitor Avacincaptad Pegol for Geographic Atrophy Due to Age-Related Macular Degeneration: A Randomized Pivotal Phase 2/3 Trial.

PURPOSE: The complement pathway may play a key role in the pathogenesis of age-related macular degeneration (AMD). The safety and efficacy of avacincaptad pegol (Zimura, IVERIC bio Inc, New York, NY), a C5 inhibitor, were assessed in participants with geographic atrophy (GA) secondary to AMD (GATHER1 Study). DESIGN: International, prospective, randomized, double-masked, sham-controlled, pivotal phase 2/3 clinical trial. PARTICIPANTS: A total of 286 participants with GA secondary to AMD. MAIN OUTCOME MEASURES: The primary efficacy endpoint was the mean rate of change in GA over 12 months measured by fundus autofluorescence (FAF) at 3 timepoints: baseline, month 6, and month 12. RESULTS: The reduction in the mean rate of GA growth (square root transformation) over 12 months was 27.4% (P = 0.0072) for the avacincaptad pegol 2 mg cohort and 27.8% (P = 0.0051) for the avacincaptad pegol 4 mg cohort compared with their corresponding sham cohorts. The results for both dose groups were statistically significant. Avacincaptad pegol was generally well tolerated after monthly administration over 12 months. There were no avacincaptad pegol-related adverse events (AEs) or inflammation. Further, there were no ocular serious AEs (SAEs) and no cases of endophthalmitis. The most frequent ocular AEs were related to the injection procedure. CONCLUSIONS: Intravitreal administration of avacincaptad pegol 2 mg and 4 mg led to a significant reduction of GA growth in eyes with AMD over a 12-month period. Because C5 inhibition theoretically preserves C3 activity, it may offer additional safety advantages. A second confirmatory pivotal clinical trial is underway to confirm the efficacy and safety of avacincaptad pegol in slowing the GA growth (GATHER2 Study).

Occlusive Retinal Vasculitis Following Intravitreal Brolucizumab.

PURPOSE: To analyze a case series of retinal vasculitis reported to the American Society of Retina Specialists (ASRS) following Food and Drug Administration approval of brolucizumab for treatment of neovascular age-related macular degeneration. METHODS: The ASRS Research and Safety in Therapeutics Committee analyzed clinical and imaging characteristics from submitted reports of retinal vasculitis after brolucizumab. RESULTS: Retinal vasculitis was reported in 26 eyes of 25 patients (22 [88%] female) after treatment with brolucizumab. Imaging studies were available for 24 of 26 eyes. Most cases (92%) were associated with intraocular inflammation, which presented at a mean of 25 days (range, 3-63 days) after the most recent brolucizumab injection. Mean visual acuity (VA) was 20/52 (range, 20/25-4/200) before the adverse event, 20/151 (range, 20/25-hand motion) at presentation of the adverse event, and 20/243 (range, 20/30-light perception) at last follow-up. Twelve eyes (46%) had a greater than 3-line decrease in VA at final follow-up, and 12 eyes (46%) had a final VA of 20/200 or worse. Analysis of retinal imaging identified vasculopathy that involved retinal arteries (91%), retinal veins (79%), and choroidal vessels (48%). Occlusive disease was apparent on imaging in 83% of eyes. Treatment approaches were varied. CONCLUSIONS: Retinal vasculitis has been identified in a series of eyes following brolucizumab. Although a few eyes in this series were asymptomatic or minimally symptomatic, some eyes had significant vision loss. A careful examination for signs of active inflammation prior to brolucizumab injection is recommended. Once vasculopathy is suspected, angiographic imaging may help define the spectrum of involvement. Optimal treatment strategies remain unknown.

Phase 1 Study of OPT-302 Inhibition of Vascular Endothelial Growth Factors C and D for Neovascular Age-Related Macular Degeneration.

PURPOSE: OPT-302 is a novel inhibitor of vascular endothelial growth factor (VEGF)-C and VEGF-D. A phase 1 trial assessed the safety of intravitreal OPT-302 as monotherapy or combined with ranibizumab (Lucentis; Genentech, South San Francisco, CA) in patients with neovascular age-related macular degeneration (nAMD). DESIGN: Open-label, dose escalation followed by a randomized dose expansion. PARTICIPANTS: Fifty-one patients with nAMD who were either treatment naïve (n = 25) or previously were treated with anti-VEGF A therapy (n = 26). METHODS: In the dose escalation, groups of 5 patients in 4 cohorts received ascending doses of OPT-302 (0.3 mg, 1 mg, or 2 mg) in combination with ranibizumab (0.5 mg), or as monotherapy (2 mg). In the dose expansion, 31 patients were randomized (3:1) to OPT-302 (2 mg) in combination with ranibizumab (n = 23) or as monotherapy (n = 8). Participants received three intravitreal treatments of OPT-302 once every 4 weeks either with or without ranibizumab. MAIN OUTCOME MEASURES: Safety and tolerability, OPT-302 pharmacokinetics and immunogenicity, effects on best-corrected visual acuity (BCVA), and anatomic changes. RESULTS: Intravitreal OPT-302 with or without ranibizumab was well tolerated with low systemic exposure, no dose-limiting toxicities and no immunogenicity. In patients receiving OPT-302 monotherapy, 7 of 13 (54%) did not require rescue anti-VEGF-A therapy and the mean change in BCVA from baseline to week 12 was +5.6 letters (range, 0-18 letters). Mean BCVA gains from baseline to week 12 following combination OPT-302 with ranibizumab were +10.8 letters (95% confidence interval [CI], 4-17; n = 18) in treatment-naïve patients and +4.9 letters (95% CI, 3-7; n = 19) in previously treated patients, respectively. Corresponding reductions in mean central subfield thickness at week 12 in both groups were -119 µm (95% CI, -176 to -62 µm) and -54 µm (95% CI, -82 to -26 µm), respectively, whilst 50% of treatment-naïve patients also showed no detectable choroidal neovascularization at week 12 on fluorescein angiography. CONCLUSIONS: Intravitreal OPT-302 inhibition of VEGF-C and -D was well tolerated, and OPT-302 combination therapy may overcome an escape mechanism to VEGF-A suppression in the management of nAMD.

Emixustat Hydrochloride for Geographic Atrophy Secondary to Age-Related Macular Degeneration: A Randomized Clinical Trial.

PURPOSE: To determine whether emixustat hydrochloride (emixustat) reduces the rate of enlargement of geographic atrophy (GA) compared with placebo in subjects with age-related macular degeneration (AMD) and to evaluate the safety and tolerability of emixustat over 24 months of treatment. DESIGN: Multicenter, randomized, double-masked, placebo-controlled, phase 2b/3 clinical trial. PARTICIPANTS: Patients with GA secondary to AMD, a visual acuity score of at least 35 letters, and GA with a total area of 1.25 to 18 mm2 were enrolled. METHODS: Subjects were randomized (1:1:1:1) to emixustat 2.5 mg, 5 mg, 10 mg, or placebo, administered orally once daily for 24 months. Visits included screening, baseline, and months 1, 2, 3, 6, 9, 12, 15, 18, 21, 24, and 25. MAIN OUTCOME MEASURES: The primary efficacy end point was the mean annual growth rate of total GA area in the study eye, as measured by a central reading center using fundus autofluorescence (FAF) images. The change from baseline in normal luminance best-corrected visual acuity (NL-BCVA) was a secondary efficacy end point. RESULTS: Of 508 randomized subjects, 320 completed the study. Demographics and baseline characteristics were comparable between treatment groups. On average, GA lesions in the study eye grew at a similar rate in each group (emixustat: 1.69 to 1.84 mm2/year; placebo: 1.69 mm2/year; P ≥ 0.81). Changes in NL-BCVA were also comparable between groups. Subjects with a larger low luminance deficit (LLD) at baseline (≥20 letters) demonstrated a more rapid growth of GA over 24 months. No relationship was observed between the risk-allele status of the AMD-associated single-nucleotide polymorphisms tested and the growth rate of GA. The most common adverse events in emixustat-treated subjects were delayed dark adaptation (55%), chromatopsia (18%), visual impairment (15%), and erythropsia (15%). CONCLUSIONS: Emixustat did not reduce the growth rate of GA in AMD. The most common adverse events were ocular in nature and likely related to the drug's mechanism of action. Data gained from this study over a 2-year period add to the understanding of the natural history of GA and the baseline characteristics affecting the growth rate of GA.

Retinal amyloid pathology and proof-of-concept imaging trial in Alzheimer's disease.

BACKGROUND: Noninvasive detection of Alzheimer's disease (AD) with high specificity and sensitivity can greatly facilitate identification of at-risk populations for earlier, more effective intervention. AD patients exhibit a myriad of retinal pathologies, including hallmark amyloid ß-protein (Aß) deposits. METHODS: Burden, distribution, cellular layer, and structure of retinal Aß plaques were analyzed in flat mounts and cross sections of definite AD patients and controls (n = 37). In a proof-of-concept retinal imaging trial (n = 16), amyloid probe curcumin formulation was determined and protocol was established for retinal amyloid imaging in live patients. RESULTS: Histological examination uncovered classical and neuritic-like Aß deposits with increased retinal Aß42 plaques (4.7-fold; P = 0.0063) and neuronal loss (P = 0.0023) in AD patients versus matched controls. Retinal Aß plaque mirrored brain pathology, especially in the primary visual cortex (P = 0.0097 to P = 0.0018; Pearson's r = 0.84-0.91). Retinal deposits often associated with blood vessels and occurred in hot spot peripheral regions of the superior quadrant and innermost retinal layers. Transmission electron microscopy revealed retinal Aß assembled into protofibrils and fibrils. Moreover, the ability to image retinal amyloid deposits with solid-lipid curcumin and a modified scanning laser ophthalmoscope was demonstrated in live patients. A fully automated calculation of the retinal amyloid index (RAI), a quantitative measure of increased curcumin fluorescence, was constructed. Analysis of RAI scores showed a 2.1-fold increase in AD patients versus controls (P = 0.0031). CONCLUSION: The geometric distribution and increased burden of retinal amyloid pathology in AD, together with the feasibility to noninvasively detect discrete retinal amyloid deposits in living patients, may lead to a practical approach for large-scale AD diagnosis and monitoring. FUNDING: National Institute on Aging award (AG044897) and The Saban and The Marciano Family Foundations.

Combination verteporfin photodynamic therapy ranibizumab-dexamethasone in choroidal neovascularization due to age-related macular degeneration: results of a phase II randomized trial.

PURPOSE: To assess whether combination therapy (CT) reduces retreatments when compared to ranibizumab monotherapy (RM), while safely maintaining similar vision outcomes. METHODS: In this 24-month trial, patients with age-related macular degeneration (AMD) were randomized to 1) quarter-fluence or 2) half-fluence triple therapy (verteporfin photodynamic therapy [vPDT] + ranibizumab + dexamethasone), 3) half-fluence double therapy (vPDT + ranibizumab), or 4) RM. The primary outcomes were number of retreatment visits and change from baseline in visual acuity (VA) at 12 months. RESULTS: One hundred sixty-two subjects enrolled. There were 4.0 (P=0.02), 3.2 (P<0.001), 4.1 (P=0.03), and 5.7 retreatment visits through month 12, and 5.9 (P=0.03), 4.3 (P<0.001), 5.9 (P=0.02) and 8.7 through month 24, in groups 1, 2, 3, and 4, respectively (P-value comparing with RM). Month 12 VA score change from baseline (95% confidence interval) was +3.6 (-0.9 to +8.1), +6.8 (+2.4 to +11.1), +5.0 (+0.6 to +9.3), and +6.5 (+1.7 to +11.4), respectively. CONCLUSION: CT resulted in significantly fewer retreatment visits than a RM regimen at months 12 and 24. VA results appeared similar although wide confidence intervals preclude conclusions regarding vision outcomes.

Dual Antagonism of PDGF and VEGF in Neovascular Age-Related Macular Degeneration: A Phase IIb, Multicenter, Randomized Controlled Trial.

PURPOSE: To assess the safety and efficacy of E10030 (Fovista; Ophthotech, New York, NY), a platelet-derived growth factor (PDGF) antagonist, administered in combination with the anti-vascular endothelial growth factor (VEGF) agent ranibizumab (Lucentis; Roche, Basel, Switzerland) compared with ranibizumab monotherapy in patients with neovascular age-related macular degeneration (nAMD). DESIGN: Phase IIb global, multicenter, randomized, prospective, double-masked, controlled superiority trial. PARTICIPANTS: Four hundred forty-nine patients with treatment-naïve nAMD. METHODS: Participants were randomized in a 1:1:1 ratio to 1 of the following 3 intravitreal treatment groups: E10030 0.3 mg in combination with ranibizumab 0.5 mg, E10030 1.5 mg in combination with ranibizumab 0.5 mg, and sham in combination with ranibizumab 0.5 mg (anti-VEGF monotherapy). Drugs were administered monthly in each of the groups for a total duration of 24 weeks. MAIN OUTCOME MEASURES: The prespecified primary end point was the mean change in visual acuity (VA; Early Treatment Diabetic Retinopathy [ETDRS] letters) from baseline to 24 weeks. RESULTS: No significant safety issues were observed in any treatment group. The E10030 (1.5 mg) combination therapy regimen met the prespecified primary end point of superiority in mean VA gain compared with anti-VEGF monotherapy (10.6 compared with 6.5 ETDRS letters at week 24; P = 0.019). A dose-response relationship was evident at each measured time point commencing at 4 weeks. Visual acuity outcomes favored the E10030 1.5 mg combination therapy group regardless of baseline VA, lesion size, or central subfield thickness on optical coherence tomography. All clinically relevant treatment end points of visual benefit (≥15 ETDRS letter gain, final VA ≥20/40 or ≥20/25) and visual loss (≥1 ETDRS line loss, ≥2 ETDRS line loss, final VA ≤20/125 or ≤20/200) favored the E10030 1.5 mg combination group. CONCLUSIONS: In this phase IIb clinical trial, a 62% relative benefit from baseline was noted in the E10030 1.5 mg combination therapy group compared with the anti-VEGF monotherapy group. A favorable safety and efficacy profile of E10030 combination therapy for nAMD was evident across multiple clinically relevant end points. This highly powered study provides strong rationale for a confirmatory phase III clinical trial.

Multifocal choroiditis and panuveitis presenting with progressive equatorial linear streaks: evolution of Schlaegel lines documented with multimodal imaging.

PURPOSE: To describe the progressive, peripheral linear streaks of the equatorial retina, known as Schlaegel lines, in multifocal choroiditis and panuveitis (MCP). METHODS: A case report of a 13-year-old girl with MCP showed progression of retinal linear streaks. Extensive systemic and ophthalmologic investigations were performed. RESULTS: Linear streaks in MCP showed progression before the institution of immunomodulatory treatment. Infrared imaging showed hyperreflectivity of the lesions with surrounding hyporeflectivity. Optical coherence tomography showed elevated and irregular hyperreflectivity of the retinal pigment epithelium and choroidal hyperreflectivity. These findings, including the clinical progression before immunomodulatory therapy and negative systemic evaluation for infectious entities, are consistent with MCP. CONCLUSION: Patients with linear streaks in the setting of atypical MCP can progress and should be treated with adequate systemic corticosteroids and immunomodulatory agents. This case is unique in that it shows the evolution of Schlaegel lines using a multimodal imaging approach. Multimodal imaging can provide ancillary evidence of disease activity.

Long-term outcomes in patients with retinal vein occlusion treated with ranibizumab: the RETAIN study.

OBJECTIVE: To determine long-term outcomes of patients with ranibizumab-treated retinal vein occlusion (RVO). DESIGN: Prospective follow-up of a subset of patients from 2 phase 3 trials. PARTICIPANTS: Thirty-four patients with branch RVO (BRVO) and 32 with central RVO (CRVO) who completed the Genentech-sponsored ranibizumab study RVO trials. METHODS: Patients seen every month in year 1 and at least every 3 months in year 2 were treated with ranibizumab for intraretinal fluid. Patients requiring injections on consecutive visits were treated with ranibizumab plus scatter photocoagulation. MAIN OUTCOME MEASURES: Mean improvement in best-corrected visual acuity (BCVA) and percentage of patients with edema resolution. RESULTS: With a mean follow-up of 49.0 months, 17 of 34 BRVO patients (50%) had edema resolution defined as no intraretinal fluid for 6 months or more after the last injection. The last injection was given within 2 years of treatment initiation in 76%. The mean number of injections required in unresolved patients in year 4 was 3.2. In patients with resolved edema mean improvement in BCVA was 25.9 letters versus 17.1 letters (P = 0.09) in unresolved patients, and in both groups, approximately 80% had a final BCVA of 20/40 or better. With a mean follow-up of 49.7 months, 14 of 32 CRVO patients (44%) had edema resolution, with 71% receiving their last injection within 2 years of treatment initiation. The mean number of injections in unresolved patients in year 4 was 5.9. Compared with patients with unresolved CRVO, patients with resolved disease had greater improvement in BCVA (25.2 vs. 4.3 letters; P = 0.002), and a greater percentage had a final BCVA of 20/40 or better (64.3% vs. 27.8%; P = 0.04). Nine patients with BRVO and 9 with CRVO received scatter photocoagulation, and with mean follow-up of 9 months (BRVO) and 11 months (CRVO) after last laser, only 1 in each group had resolution of edema. CONCLUSIONS: Long-term outcomes in BRVO patients treated with ranibizumab were excellent, and although half still required occasional injections after 4 years, they maintained good visual potential. A substantial minority (44%) of patients with ranibizumab-treated CRVO had edema resolution and a good outcome within 4 years, but most (56%) still required frequent injections, had reduced visual potential, and have a guarded prognosis.

Intravitreal bevacizumab (Avastin) in the treatment of proliferative diabetic retinopathy.

PURPOSE: To report the biologic effect of intravitreal bevacizumab in patients with retinal and iris neovascularization secondary to diabetes mellitus. DESIGN: Interventional, consecutive, retrospective, case series. PARTICIPANTS: Forty-five eyes of 32 patients with retinal and/or iris neovascularization secondary to diabetes mellitus. METHODS: Patients received intravitreal bevacizumab (6.2 microg-1.25 mg). Ophthalmic evaluations included nonstandardized Snellen visual acuity (VA), complete ophthalmic examination, fluorescein angiography, and optical coherence tomography. MAIN OUTCOME MEASURES: Change in fluorescein angiographic leakage of the proliferative diabetic retinopathy (PDR). Secondary outcomes included changes in Snellen VA. RESULTS: No significant ocular or systemic adverse events were observed. All patients with neovascularization demonstrated by fluorescein angiography (44/44 eyes) had complete (or at least partial) reduction in leakage of the neovascularization within 1 week after the injection. Complete resolution of angiographic leakage of neovascularization of the disc was noted in 19 of 26 (73%) eyes, and leakage of iris neovascularization completely resolved in 9 of 11 (82%) eyes. The leakage was noted to diminish as early as 24 hours after injection. In addition to the reduction in angiographic leakage, the neovascularization clinically appeared to involute in many patients with a reduction in the caliber or presence of perfused blood vessels. In 2 cases, a subtle decrease in leakage of retinal or iris neovascularization in the fellow uninjected eye was noted, raising the possibility that therapeutic systemic levels were achieved after intravitreal injection. Recurrence of fluorescein leakage varied. Recurrent leakage was seen as early as 2 weeks in one case, whereas in other cases, no recurrent leakage was noted at last follow-up of 11 weeks. CONCLUSIONS: Short-term results suggest that intravitreal bevacizumab is well tolerated and associated with a rapid regression of retinal and iris neovascularization secondary to PDR. A consistent biologic effect was noted, even with the lowest dose (6.2 microg) tested, supporting proof of concept. The observation of a possible therapeutic effect in the fellow eye raises concern that systemic side effects are possible in patients undergoing treatment with intravitreal bevacizumab (1.25 mg), and lower doses may achieve a therapeutic result with less risk of systemic side effects. Further study is indicated.

Pigment epithelium-derived factor suppresses ischemia-induced retinal neovascularization and VEGF-induced migration and growth.

PURPOSE: To determine the effect of pigment epithelium-derived factor (PEDF) in a mouse model of ischemia-induced retinal neovascularization and on vascular endothelial growth factor (VEGF)--induced migration and growth of cultured microvascular endothelial cells. METHODS: Human recombinant PEDF was expressed in the human embryonic kidney 293 cell line and purified by ammonium sulfate precipitation and cation exchange chromatography. C57BL/6 mice were exposed to 75% oxygen from postnatal day (P)7 to P12 and then returned to room air. Mice received intravitreal injections of 2 microg PEDF in one eye and vehicle in the contralateral eye on P12 and P14. At P17, mice were killed and eyes enucleated for quantitation of retinal neovascularization. The mitogenic and motogeneic effects of VEGF on cultured bovine retinal and adrenal capillary endothelial cells were examined in the presence or absence of PEDF, using cell counts and migration assays. RESULTS: Two species of human recombinant PEDF, denoted A and B, were purified to apparent homogeneity. PEDF B appeared to comigrate on SDS-PAGE with PEDF from human vitreous samples. Changes in electrophoretic mobility after peptide-N-glycosidase F (PNGase F) digestion suggest that both PEDF forms contain N-linked carbohydrate. Analyses of the intact proteins by liquid chromatography-electrospray mass spectrometry (LC-ESMS) revealed the major molecular weight species for PEDF A (47,705 +/- 4) and B (46,757 +/- 5). LC-ESMS analysis of tryptic peptides indicated that PEDF A and B exhibit differences in glycopeptides containing N-acetylneuraminic acid (NeuAc) and N-acetylhexosamine (HexNAc). Intravitreal administration of either species of PEDF significantly inhibited retinal neovascularization (83% for PEDF A and 55% for PEDF B; P = 0.024 and 0.0026, respectively). PEDF A and B (20 nM) suppressed VEGF-induced retinal microvascular endothelial cell proliferation by 48.8% and 41.4%, respectively, after 5 days (P < 0.001) and VEGF-induced migration by 86.5% +/- 16.7% and 78.1% +/- 22.3%, respectively, after 4 hours (P = 0.004 and P = 0.008, respectively). CONCLUSIONS: These data indicate that elevated concentrations of PEDF inhibit VEGF-induced retinal endothelial cell growth and migration and retinal neovascularization. These findings suggest that localized administration of PEDF may be an effective approach for the treatment of ischemia-induced retinal neovascular disorders.