Peter A. Campochiaro

Angiopoietin-2 Is Required for Postnatal Angiogenesis and Lymphatic Patterning, and Only the Latter Role Is Rescued by Angiopoietin-1

VEGF and Angiopoietin-1 requisitely collaborate during blood vessel development. While Angiopoietin-1 obligately activates its Tie2 receptor, Angiopoietin-2 can activate Tie2 on some cells, while it blocks Tie2 activation on others. Our analysis of mice lacking Angiopoietin-2 reveals that Angiopoietin-2 is dispensable for embryonic vascular development but is requisite for subsequent angiogenic remodeling. Unexpectedly, mice lacking Angiopoietin-2 also exhibit major lymphatic vessel defects. Genetic rescue with Angiopoietin-1 corrects the lymphatic, but not the angiogenesis, defects, suggesting that Angiopoietin-2 acts as a Tie2 agonist in the former setting, but as an antagonist in the latter setting. Our studies define a vascular growth factor whose primary role is in postnatal angiogenic remodeling and also demonstrate that members of the VEGF and Angiopoietin families collaborate during development of the lymphatic vasculature.

Ranibizumab for Macular Edema following Central Retinal Vein Occlusion: Six-Month Primary End Point Results of a Phase III Study

PURPOSE To assess the efficacy and safety of intraocular injections of 0.3 mg or 0.5 mg ranibizumab in patients with macular edema after central retinal vein occlusion (CRVO). DESIGN Prospective, randomized, sham injection-controlled, double-masked, multicenter clinical trial. PARTICIPANTS A total of 392 patients with macular edema after CRVO. METHODS Eligible patients were randomized 1:1:1 to receive monthly intraocular injections of 0.3 or 0.5 mg of ranibizumab or sham injections. MAIN OUTCOME MEASURES The primary efficacy outcome measure was mean change from baseline best-corrected visual acuity (BCVA) letter score at month 6. Secondary outcomes included other parameters of visual function and central foveal thickness (CFT). RESULTS Mean (95% confidence interval [CI]) change from baseline BCVA letter score at month 6 was 12.7 (9.9-15.4) and 14.9 (12.6-17.2) in the 0.3 mg and 0.5 mg ranibizumab groups, respectively, and 0.8 (-2.0 to 3.6) in the sham group (P<0.0001 for each ranibizumab group vs. sham). The percentage of patients who gained > or =15 letters in BCVA at month 6 was 46.2% (0.3 mg) and 47.7% (0.5 mg) in the ranibizumab groups and 16.9% in the sham group (P<0.0001 for each ranibizumab group vs. sham). At month 6, significantly more ranibizumab-treated patients (0.3 mg = 43.9%; 0.5 mg = 46.9%) had BCVA of > or = 20/40 compared with sham patients (20.8%; P<0.0001 for each ranibizumab group vs. sham), and CFT had decreased by a mean of 434 microm (0.3 mg) and 452 microm (0.5 mg) in the ranibizumab groups and 168 microm in the sham group (P<0.0001 for each ranibizumab group vs. sham). The median percent reduction in excess foveal thickness at month 6 was 94.0% and 97.3% in the 0.3 mg and 0.5 mg groups, respectively, and 23.9% in the sham group. The safety profile was consistent with previous phase III ranibizumab trials, and no new safety events were identified in patients with CRVO. CONCLUSIONS Intraocular injections of 0.3 mg or 0.5 mg ranibizumab provided rapid improvement in 6-month visual acuity and macular edema following CRVO, with low rates of ocular and nonocular safety events.

Cell Type–Specific Regulation of Angiogenic Growth Factor Gene Expression and Induction of Angiogenesis in Nonischemic Tissue by a Constitutively Active Form of Hypoxia-Inducible Factor 1

Abstract— Understanding molecular mechanisms regulating angiogenesis may lead to novel therapies for ischemic disorders. Hypoxia-inducible factor 1 (HIF-1) activates vascular endothelial growth factor (VEGF) gene expression in hypoxic/ischemic tissue. In this study we demonstrate that exposure of primary cultures of cardiac and vascular cells to hypoxia or AdCA5, an adenovirus encoding a constitutively active form of HIF-1&agr;, modulates the expression of genes encoding the angiogenic factors angiopoietin-1 (ANGPT1), ANGPT2, placental growth factor, and platelet-derived growth factor-B. Loss-of-function effects were also observed in HIF-1&agr;–null embryonic stem cells. Depending on the cell type, expression of ANGPT1 and ANGPT2 was either activated or repressed in response to hypoxia or AdCA5. In all cases, there was complete concordance between the effects of hypoxia and AdCA5. Injection of AdCA5 into mouse eyes induced neovascularization in multiple capillary beds, including those not responsive to VEGF alone. Analysis of gene expression revealed increased expression of ANGPT1, ANGPT2, platelet-derived growth factor-B, placental growth factor, and VEGF mRNA in AdCA5-injected eyes. These results indicate that HIF-1 functions as a master regulator of angiogenesis by controlling the expression of multiple angiogenic growth factors and that adenovirus-mediated expression of a constitutively active form of HIF-1&agr; is sufficient to induce angiogenesis in nonischemic tissue of an adult animal.

Ranibizumab for Macular Edema following Central Retinal Vein Occlusion

PURPOSE To assess efficacy and safety of intraocular injections of 0.3 mg or 0.5 mg ranibizumab in patients with macular edema following branch retinal vein occlusion (BRVO). DESIGN Prospective, randomized, sham injection-controlled, double-masked, multicenter clinical trial. PARTICIPANTS A total of 397 patients with macular edema following BRVO. METHODS Eligible patients were randomized 1:1:1 to receive monthly intraocular injections of 0.3 mg or 0.5 mg of ranibizumab or sham injections. MAIN OUTCOME MEASURES The primary efficacy outcome measure was mean change from baseline best-corrected visual acuity (BCVA) letter score at month 6. Secondary outcomes included other parameters of visual function and central foveal thickness (CFT). RESULTS Mean (95% confidence interval [CI]) change from baseline BCVA letter score at month 6 was 16.6 (14.7-18.5) and 18.3 (16.0-20.6) in the 0.3 mg and 0.5 mg ranibizumab groups and 7.3 (5.1-9.5) in the sham group (P<0.0001 for each ranibizumab group vs sham). The percentage of patients who gained > or =15 letters in BCVA at month 6 was 55.2% (0.3 mg) and 61.1% (0.5 mg) in the ranibizumab groups and 28.8% in the sham group (P<0.0001 for each ranibizumab group vs sham). At month 6, significantly more ranibizumab-treated patients (0.3 mg, 67.9%; 0.5 mg, 64.9%) had BCVA of > or =20/40 compared with sham patients (41.7%; P<0.0001 for each ranibizumab group vs sham); and CFT had decreased by a mean of 337 microm (0.3 mg) and 345 microm (0.5 mg) in the ranibizumab groups and 158 microm in the sham group (P<0.0001 for each ranibizumab group vs sham). The median percent reduction in excess foveal thickness at month 6 was 97.0% and 97.6% in 0.3 mg and 0.5 mg groups and 27.9% in the sham group. More patients in the sham group (54.5%) received rescue grid laser compared with the 0.3 mg (18.7%) and 0.5 mg (19.8%) ranibizumab groups. The safety profile was consistent with previous phase III ranibizumab trials, and no new safety events were identified in patients with BRVO. CONCLUSIONS Intraocular injections of 0.3 mg or 0.5 mg ranibizumab provided rapid, effective treatment for macular edema following BRVO with low rates of ocular and nonocular safety events.

Genetic variants near TIMP3 and high-density lipoprotein–associated loci influence susceptibility to age-related macular degeneration

We executed a genome-wide association scan for age-related macular degeneration (AMD) in 2,157 cases and 1,150 controls. Our results validate AMD susceptibility loci near CFH (P < 10−75), ARMS2 (P < 10−59), C2/CFB (P < 10−20), C3 (P < 10−9), and CFI (P < 10−6). We compared our top findings with the Tufts/Massachusetts General Hospital genome-wide association study of advanced AMD (821 cases, 1,709 controls) and genotyped 30 promising markers in additional individuals (up to 7,749 cases and 4,625 controls). With these data, we identified a susceptibility locus near TIMP3 (overall P = 1.1 × 10−11), a metalloproteinase involved in degradation of the extracellular matrix and previously implicated in early-onset maculopathy. In addition, our data revealed strong association signals with alleles at two loci (LIPC, P = 1.3 × 10−7; CETP, P = 7.4 × 10−7) that were previously associated with high-density lipoprotein cholesterol (HDL-c) levels in blood. Consistent with the hypothesis that HDL metabolism is associated with AMD pathogenesis, we also observed association with AMD of HDL-c—associated alleles near LPL (P = 3.0 × 10−3) and ABCA1 (P = 5.6 × 10−4). Multilocus analysis including all susceptibility loci showed that 329 of 331 individuals (99%) with the highest-risk genotypes were cases, and 85% of these had advanced AMD. Our studies extend the catalog of AMD associated loci, help identify individuals at high risk of disease, and provide clues about underlying cellular pathways that should eventually lead to new therapies.

Sustained Benefits from Ranibizumab for Macular Edema Following Branch Retinal Vein Occlusion: 12-Month Outcomes of a Phase III Study

PURPOSE Assess 12-month efficacy and safety of intraocular injections of 0.3 mg or 0.5 mg ranibizumab in patients with macular edema after branch retinal vein occlusion (BRVO). DESIGN Prospective, randomized, sham injection-controlled, double-masked, multicenter trial. PARTICIPANTS A total of 397 patients with macular edema after BRVO. METHODS Eligible patients were randomized 1:1:1 to 6 monthly injections of 0.3 mg or 0.5 mg ranibizumab or sham injections. After 6 months, all patients with study eye best-corrected visual acuity (BCVA) ≤20/40 or central subfield thickness ≥250 μm were to receive ranibizumab. Patients could receive rescue laser treatment once during the treatment period and once during the observation period if criteria were met. MAIN OUTCOME MEASURES The main efficacy outcome reported is mean change from baseline BCVA letter score at month 12. Additional visual and anatomic parameters were assessed. RESULTS Mean (95% confidence interval) change from baseline BCVA letter score at month 12 was 16.4 (14.5-18.4) and 18.3 (15.8-20.9) in the 0.3 mg and 0.5 mg groups, respectively, and 12.1 (9.6-14.6) in the sham/0.5 mg group (P<0.01, each ranibizumab group vs. sham/0.5 mg). The percentage of patients who gained ≥15 letters from baseline BCVA at month 12 was 56.0% and 60.3% in the 0.3 mg and 0.5 mg groups, respectively, and 43.9% in the sham/0.5 mg group. On average, there was a marked reduction in central foveal thickness (CFT) after the first as-needed injection of 0.5 mg ranibizumab in the sham/0.5 mg group, which was sustained through month 12. No new ocular or nonocular safety events were identified. CONCLUSIONS At month 12, treatment with ranibizumab as needed during months 6-11 maintained, on average, the benefits achieved by 6 monthly ranibizumab injections in patients with macular edema after BRVO, with low rates of ocular and nonocular safety events. In the sham/0.5 mg group, treatment with ranibizumab as needed for 6 months resulted in rapid reduction in CFT to a similar level as that in the 0.3 mg ranibizumab treatment group and an improvement in BCVA, but not to the extent of that in the 2 ranibizumab groups. Intraocular injections of ranibizumab provide an effective treatment for macular edema after BRVO. FINANCIAL DISCLOSURE(S) Proprietary or commercial disclosure may be found after the references.

Blockade of Vascular Endothelial Cell Growth Factor Receptor Signaling Is Sufficient to Completely Prevent Retinal Neovascularization

Retinal vasculogenesis and ischemic retinopathies provide good model systems for study of vascular development and neovascularization (NV), respectively. Vascular endothelial cell growth factor (VEGF) has been implicated in the pathogenesis of retinal vasculogenesis and in the development of retinal NV in ischemic retinopathies. However, insulin-like growth factor-I and possibly other growth factors also participate in the development of retinal NV and intraocular injections of VEGF antagonists only partially inhibit retinal NV. One possible conclusion from these studies is that it is necessary to block other growth factors in addition to VEGF to achieve complete inhibition of retinal NV. We recently demonstrated that a partially selective kinase inhibitor, PKC412, that blocks phosphorylation by VEGF and platelet-derived growth factor (PDGF) receptors and several isoforms of protein kinase C (PKC), completely inhibits retinal NV. In this study, we have used three additional selective kinase inhibitors with different selectivity profiles to explore the signaling pathways involved in retinal NV. PTK787, a drug that blocks phosphorylation by VEGF and PDGF receptors, but not PKC, completely inhibited retinal NV in murine oxygen-induced ischemic retinopathy and partially inhibited retinal vascularization during development. CGP 57148 and CGP 53716, two drugs that block phosphorylation by PDGF receptors, but not VEGF receptors, had no significant effect on retinal NV. These data and our previously published study suggest that regardless of contributions by other growth factors, VEGF signaling plays a critical role in the pathogenesis of retinal NV. Inhibition of VEGF receptor kinase activity completely blocks retinal NV and is an excellent target for treatment of proliferative diabetic retinopathy and other ischemic retinopathies.

Two-year outcomes of the ranibizumab for edema of the mAcula in diabetes (READ-2) study.

OBJECTIVES To determine the long-term effects of ranibizumab (RBZ) in patients with diabetic macular edema (DME). DESIGN Prospective, randomized, interventional, multicenter clinical trial. PARTICIPANTS One hundred twenty-six patients with DME. METHODS Subjects were randomized 1:1:1 to receive 0.5 mg RBZ at baseline and months 1, 3, and 5 (group 1), focal or grid laser photocoagulation at baseline and month 3 if needed (group 2), or a combination of 0.5 mg RBZ and focal or grid laser at baseline and month 3 (group 3). Starting at month 6, if retreatment criteria were met, all subjects could be treated with RBZ. MAIN OUTCOME MEASURES The mean change from baseline in best-corrected visual acuity (BCVA) at month 24. RESULTS After the primary end point at month 6, most patients in all groups were treated only with RBZ, and the mean number of injections was 5.3, 4.4, and 2.9 during the 18-month follow-up period in groups 1, 2, and 3, respectively. For the 33 patients in group 1, 34 patients in group 2, and 34 patients in group 3 who remained in the study through 24 months, the mean improvement in BCVA was 7.4, 0.5, and 3.8 letters at the 6-month primary end point, compared with 7.7, 5.1, and 6.8 letters at month 24, and the percentage of patients who gained 3 lines or more of BCVA was 21, 0, and 6 at month 6, compared with 24, 18, and 26 at month 24. The percentage of patients with 20/40 or better Snellen equivalent at month 24 was 45% in group 1, 44% in group 2, and 35% in group 3. Mean foveal thickness (FTH), defined as center subfield thickness, at month 24 was 340 μm, 286 μm, and 258 μm for groups 1, 2, and 3, respectively, and the percentage of patients with center subfield thickness of 250 μm or less was 36%, 47%, and 68%, respectively. CONCLUSIONS Intraocular injections of RBZ provided benefit for patients with DME for at least 2 years, and when combined with focal or grid laser treatments, the amount of residual edema was reduced, as were the frequency of injections needed to control edema. FINANCIAL DISCLOSURE(S) Proprietary or commercial disclosure may be found after the references.

Genome-wide association study of advanced age-related macular degeneration identifies a role of the hepatic lipase gene (LIPC)

Advanced age-related macular degeneration (AMD) is the leading cause of late onset blindness. We present results of a genome-wide association study of 979 advanced AMD cases and 1,709 controls using the Affymetrix 6.0 platform with replication in seven additional cohorts (totaling 5,789 unrelated cases and 4,234 unrelated controls). We also present a comprehensive analysis of copy-number variations and polymorphisms for AMD. Our discovery data implicated the association between AMD and a variant in the hepatic lipase gene (LIPC) in the high-density lipoprotein cholesterol (HDL) pathway (discovery P = 4.53e-05 for rs493258). Our LIPC association was strongest for a functional promoter variant, rs10468017, (P = 1.34e-08), that influences LIPC expression and serum HDL levels with a protective effect of the minor T allele (HDL increasing) for advanced wet and dry AMD. The association we found with LIPC was corroborated by the Michigan/Penn/Mayo genome-wide association study; the locus near the tissue inhibitor of metalloproteinase 3 was corroborated by our replication cohort for rs9621532 with P = 3.71e-09. We observed weaker associations with other HDL loci (ABCA1, P = 9.73e-04; cholesterylester transfer protein, P = 1.41e-03; FADS1-3, P = 2.69e-02). Based on a lack of consistent association between HDL increasing alleles and AMD risk, the LIPC association may not be the result of an effect on HDL levels, but it could represent a pleiotropic effect of the same functional component. Results implicate different biologic pathways than previously reported and provide new avenues for prevention and treatment of AMD.

Suppression of ocular neovascularization with siRNA targeting VEGF receptor 1.

In this study, we used small interfering RNA (siRNA) directed against vascular endothelial growth factor receptor 1 (vegfr1) mRNA to investigate the role of VEGFR1 in ocular neovascularization (NV). After evaluating many siRNAs, Sirna-027 was identified; it cleaved vegfr1 mRNA at the predicted site and reduced its levels in cultured endothelial cells and in mouse models of retinal and choroidal neovascularization (CNV). Compared to injection of an inverted control sequence, quantitative reverse transcriptase-PCR demonstrated statistically significant reductions of 57 and 40% in vegfr1 mRNA after intravitreous or periocular injection of Sirna-027, respectively. Staining showed uptake of 5-bromodeoxyuridine-labeled Sirna-027 in retinal cells that lasted between 3 and 5 days after intravitreous injection and was still present 5 days after periocular injection. In a CNV model, intravitreous or periocular injections of Sirna-027 resulted in significant reductions in the area of NV ranging from 45 to 66%. In mice with ischemic retinopathy, intravitreous injection of 1.0 μg of Sirna-027 reduced retinal NV by 32% compared to fellow eyes treated with 1.0 μg of inverted control siRNA. These data suggest that VEGFR1 plays an important role in the development of retinal and CNV and that targeting vegfr1 mRNA with siRNA has therapeutic potential.