Aqueous vascular endothelial growth factor after intravitreal injection of pegaptanib or ranibizumab in patients with age-related macular degeneration

The 20th Anniversary of Pegaptanib (MacugenTM), the First Approved Aptamer Medicine: History, Recent Advances and Future Prospects of Aptamers in Therapy

In addition to classic small-molecule drugs and modern protein-based biologics, an intriguing class of medicines is the therapeutic oligonucleotides. Most approved drugs in this category are antisense oligomers or those acting via RNA interference, both of which use base hybridization. Aptamers, also known as chemical antibodies form a smaller, yet equally interesting group of oligonucleotides that can recognize a wide range of molecular targets. Despite their high potential, only two aptamers have been approved to date, pegaptanib (MacugenTM) and avacincaptad pegol (IzervayTM), both for the treatment of age-related macular degeneration (AMD). Targeting vascular endothelial growth factor (VEGF), which plays an important role in the pathogenesis of many eye diseases, pegaptanib emerged as the first anti-VEGF agent and was used in various indications, further inspiring the development of other anti-VEGF therapies. In this review, we summarize the history of the first approved aptamer medicine, pegaptanib. We describe its chemistry and track its development from the earliest stages to the preclinical phase, clinical trials, and eventual regulatory approval. Additionally, we evaluate its position among other therapeutic agents and provide a comprehensive overview of pegaptanib's efficacy, safety, and cost-effectiveness, comparing these aspects with those of monoclonal antibodies with similar indications, bevacizumab and ranibizumab.

Effects of Humanin G (HNG) on angiogenesis and neurodegeneration markers in Age-related Macular Degeneration (AMD)

Advanced stages of Age-related Macular Degeneration (AMD) are characterized by retinal neurodegeneration and aberrant angiogenesis, and mitochondrial dysfunction contributes to the pathogenesis of AMD. In this study, we tested the hypothesis that Humanin G (HNG), a cytoprotective mitochondrial-derived peptide, positively regulates cell proliferation, cell death, and the protein levels of angiogenesis and neurodegeneration markers, in normal (control) and AMD RPE transmitochondrial cybrid cell lines. These normal and AMD RPE transmitochondrial cybrid cell lines had identical nuclei derived from mitochondria-deficient ARPE-19 cell line, but differed in mitochondrial DNA (mtDNA) content that was derived from clinically characterized AMD patients and normal (control) subjects. Cell lysates were extracted from untreated and HNG-treated AMD and normal (control) cybrid cell lines, and the Luminex XMAP multiplex assay was used to examine the protein levels of angiogenesis and neurodegeneration markers. Humanin G reduced Caspase-3/7-mediated apoptosis, improved cell proliferation, and normalized the protein levels of angiogenesis and neurodegeneration markers in AMD RPE cybrid cell lines, thereby suggesting Humanin G's positive regulatory role in AMD.

CRISPR/Cas9 mediated specific ablation of vegfa in retinal pigment epithelium efficiently regresses choroidal neovascularization

The CRISPR/Cas9 system easily edits target genes in various organisms and is used to treat human diseases. In most therapeutic CRISPR studies, ubiquitously expressed promoters, such as CMV, CAG, and EF1α, are used; however, gene editing is sometimes necessary only in specific cell types relevant to the disease. Therefore, we aimed to develop a retinal pigment epithelium (RPE)-specific CRISPR/Cas9 system. We developed a CRISPR/Cas9 system that operates only in retinal pigment epithelium (RPE) by expressing Cas9 under the RPE-specific vitelliform macular dystrophy 2 promoter (pVMD2). This RPE-specific CRISPR/pVMD2-Cas9 system was tested in human retinal organoid and mouse model. We confirmed that this system works specifically in the RPE of human retinal organoids and mouse retina. In addition, the RPE-specific Vegfa ablation using the novel CRISPR-pVMD2-Cas9 system caused regression of choroidal neovascularization (CNV) without unwanted knock-out in the neural retina in laser-induced CNV mice, which is a widely used animal model of neovascular age-related macular degeneration. RPE-specific Vegfa knock-out (KO) and ubiquitous Vegfa KO were comparable in the efficient regression of CNV. The promoter substituted, cell type-specific CRISPR/Cas9 systems can be used in specific 'target cell' therapy, which edits genes while reducing unwanted off- 'target cell' effects.

Changes in aqueous and vitreous inflammatory cytokine levels in neovascular age-related macular degeneration: a systematic review and meta-analysis

Inflammatory cytokines are involved in the pathogenesis of neovascular age-related macular degeneration (nAMD) and have been shown to be useful as diagnostic and predictive biomarkers. Given the heterogeneity of data within the literature, we aimed to quantitatively summarize data related to inflammatory cytokines in nAMD. A systematic search without year limitation was performed up to 13 April 2020. Studies were included if they provided data on aqueous or vitreous cytokine concentrations in patients with nAMD. Data were extracted from 95 studies that encompassed 3105 study eyes with nAMD and 1209 control eyes. Effect sizes were generated as standardized mean differences (SMDs) of cytokine concentrations between patients with nAMD and controls. Among the 4314 eyes in 95 studies, aqueous concentrations (standard mean difference, 95% confidence interval and p-value) of MCP-1 (0.43, 0.09 to 0.77 and p = 0.01), MIG (0.63, 0.31 to 0.94 and p = 0.0001), TGF-β (0.45, 0.07 to 0.82 and p = 0.02) and VEGF (0.64, 0.31 to 0.98 and p = 0.0001) were significantly higher in patients with nAMD compared to healthy controls. No differences, failed sensitivity analyses or insufficient data were found between patients with nAMD and healthy controls for the concentrations of the remaining cytokines and with all vitreous samples. Previous studies had shown conflicting associations with nAMD for all 27 cytokines assessed. Our analysis indicates multiple candidate cytokines other than VEGF that are implicated in nAMD and adds clarity to the previous literature. This will help focus translational research in nAMD investigating biomarkers and therapeutic targets.

THE CORRELATION BETWEEN AQUEOUS VASCULAR ENDOTHELIAL GROWTH FACTOR LEVEL AND CLINICAL ACTIVITY IN NEOVASCULAR AGE-RELATED MACULAR DEGENERATION

PURPOSE

The aim of the current study was to investigate the correlation between the pretreatment aqueous level of vascular endothelial growth factor (VEGF) and clinical activity in neovascular age-related macular degeneration.

METHODS

Patients with neovascular age-related macular degeneration treated by intravitreal ranibizumab injections and followed for 12 months were included in the current study. The treatment regimen consisted of three consecutive monthly intravitreal ranibizumab injections (loading treatment) followed by a pro re nata (PRN) treatment regimen. The aqueous VEGF levels were measured by enzyme-linked immunosorbent assay using aqueous humor samples obtained just before the first intravitreal ranibizumab injections.

RESULTS

Sixty-four eyes of 64 patients were included in the current study. The mean number of intravitreal ranibizumab injections during 12 months was 4.6 ± 1.4, and 17 eyes had no recurrence after loading treatment. The mean aqueous VEGF level was significantly higher in eyes with recurrence after loading treatment than in eyes without recurrence (107.6 vs. 83.8 pg/mL, respectively; P = 0.04) and significantly higher in eyes with recurrence within 3 months after loading treatment than in other eyes (114.9 vs. 86.7 pg/mL, respectively; P < 0.01).

CONCLUSION

Pretreatment aqueous VEGF level was significantly correlated with the likelihood of recurrence in neovascular age-related macular degeneration. The measurement of pretreatment aqueous VEGF level may be useful to determine the best treatment options for patients with neovascular age-related macular degeneration.

Anti-angiogenesis by dual action of R5K peptide conjugated itraconazole nanoparticles

Neovascular age-related macular degeneration (AMD) is a leading cause of central vision loss and irreversible blindness. Vascular endothelial growth factor (VEGF) plays an important role in neovascularization under the retina and macula by promoting endothelial cell proliferation, migration, and angiogenesis. Although anti-VEGF drugs have shown their efficacy in visual improvement, long-term use of these drugs leads to ocular and systemic complications due to the non-selectivity of the drug. In this study, the dual-mode anti-angiogenic drug delivery system, which potentially inhibited VEGF in two different ways, was developed. The itraconazole encapsulated nanoparticles, conjugated with R5K peptide, were fabricated to allow multivalent binding interactions with VEGF. The R5K peptide blocked VEGF binding to its receptor, while itraconazole altered the signaling pathway of VEGF stimulation. The dual action of this novel drug delivery system aimed to enhance the anti-angiogenic effects of individual drugs. R5K-ITZ-NPs demonstrated potent, cell-type specific, and dose-dependent inhibition of vascular endothelial cell proliferation, migration, and tube formation in response to VEGF stimulation. The physical stability study showed that R5K-ITZ-NPs were stable when stored at 4 °C. However, the drug remaining in R5K-ITZ-NPs when stored at 4 °C for 28 days were only 17.2%. The chemical stability test revealed that the degradation of R5K-ITZ-NPs followed second-order kinetics. The release profile showed the burst release of ITZ followed by sustained release of the drug This novel drug delivery system may be an option for neovascular AMD patients who are resistant to ITZ and may represent a novel therapy for AMD.

CRISPR-LbCpf1 prevents choroidal neovascularization in a mouse model of age-related macular degeneration

LbCpf1, derived from Lachnospiraceae bacterium ND2006, is a CRISPR RNA-guided endonuclease and holds promise for therapeutic applications. Here we show that LbCpf1 can be used for therapeutic gene editing in a mouse model of age-related macular degeneration (AMD). The intravitreal delivery of LbCpf1, targeted to two angiogenesis-associated genes encoding vascular endothelial growth factor A (Vegfa) and hypoxia inducing factor 1a (Hif1a), using adeno-associated virus, led to efficient gene disruption with no apparent off-target effects in the retina and retinal pigment epithelium (RPE) cells. Importantly, LbCpf1 targeted to Vegfa or Hif1a in RPE cells reduced the area of laser-induced choroidal neovascularization as efficiently as aflibercept, an anti-VEGF drug currently used in the clinic, without inducing cone dysfunction. Unlike aflibercept, LbCpf1 targeted to Vegfa or Hif1a achieved a long-term therapeutic effect on CNV, potentially avoiding repetitive injections. Taken together, these results indicate that LbCpf1-mediated in vivo genome editing to ablate pathologic angiogenesis provides an effective strategy for the treatment of AMD and other neovascularization-associated diseases.

Intravitreal injection of aflibercept, an anti-VEGF antagonist, down-regulates plasma von Willebrand factor in patients with age-related macular degeneration

We investigated the association between von Willebrand factor (VWF) and exudative age-related macular degeneration (AMD) in 114 Japanese patients. Intravitreal injection of vascular endothelial growth factor (VEGF) inhibitor is the most effective therapy for AMD. Therefore, we analyzed changes of VWF antigen (VWF:Ag) and VWF multimers (VWFMs) after intravitreal injection of aflibercept, an anti-VEGF antagonist. The relationship between polymorphisms in complement factor H (p.Y402H and p.I62V) and AMD was previously reported. In our patients, p.I62V, but not p.Y402H, was significantly associated with an increased risk of AMD. Pre-treatment plasma levels of VWF:Ag in patients with AMD were significantly higher than those in controls. Unusually large VWFMs (UL-VWFMs) were detected in the majority of AMD patients with concurrent vitreous or subretinal hemorrhage. After intravitreal injection of aflibercept, plasma levels of VWF:Ag and VEGF-A were significantly decreased. UL-VWFMs disappeared after aflibercept injection in three cases, but persisted even 1 month after injection in the other five cases. In conclusion, plasma VWF:Ag levels were significantly elevated in patients with AMD, and decreased after intravitreal aflibercept injection. VWF may play an important role in the pathophysiology of AMD, and aflibercept might improve AMD by reducing plasma levels of VWF in addition to VEGF-A.

Gene expression levels of the insulin-like growth factor family in patients with AMD before and after ranibizumab intravitreal injections

Purpose

The present study focused on the assessment of the mRNA levels of the insulin-like growth factor (IGF) family in patients with the exudative form of age-related macular degeneration (AMD) before and after ranibizumab intravitreal injections.

Patients and methods

An analysis of the expression profile of the IGF family of genes in patients with AMD was carried out using the oligonucleotide microarray and quantitative reverse transcriptase polymerase chain reaction (RT-qPCR) methods.

Results

In the peripheral blood mononuclear cells (PBMCs) obtained from AMD group receiving ranibizumab compared to the peripheral blood mononuclear cells from AMD group before ranibizumab treatment using oligonucleotide microarray technique, six statistically significant differentially expressed transcripts related to the IGF family were detected (unpaired t-test, p<0.05, fold change >1.5). Moreover, analysis using the real-time RT-qPCR technique revealed statistically significant differences in the IGF2 and IGF2R mRNA levels (Mann–Whitney U test, p<0.05) between the two groups that were studied. Statistical analyses of both oligonucleotide microarray and real-time RT-qPCR results demonstrated a significant decreased expression only for IGF2 mRNA.

Conclusion

Our results revealed a changed expression of IGF2 mRNA after ranibizumab treatment.

Aqueous vascular endothelial growth factor and clinical outcomes correlation after single intravitreal injection of bevacizumab in patients with neovascular age-related macular degeneration

Purpose

To evaluate the concentration of vascular endothelial growth factor (VEGF) in aqueous humor after a single intravitreal injection of bevacizumab (IVB) in eyes with neovascular age-related macular degeneration (AMD).

Methods

In this prospective interventional case series study, 24 eyes of 24 patients with types 1 and 2 choroidal neovascularization secondary to neovascular AMD were treated with a single intravitreal injection of bevacizumab. Aqueous humor samples were obtained before the intravitreal injection and at one week, one month, and three months follow-up periods. Best-corrected visual acuity (BCVA) and three spectral-domain optical coherence tomography parameters (central retinal thickness, macular volume and macular area) were also analyzed and correlated with VEGF expression at the baseline and each follow-up period.

Results

All of the ninety-six aqueous humor study taps were well tolerated by the study patients without adverse events. Increased VEGF levels (mean ± SD = 179.7 ± 88.3 pg/mL) were observed in the aqueous humor of all study patients before the intravitreal injection of bevacizumab. At all follow-up periods, compared to baseline, levels of VEGF significantly reduced (P < 0.0001), and BCVA significantly improved (P < 0.005). The lowest VEGF expression was observed at 1 week, and the greatest BCVA improvement occurred 1 month after treatment. At 1 month, central retinal thickness (CRT), macular volume (MV), and macular area (MA) significantly reduced compared to baseline (P < 0.0001, P = 0.0005, P = 0.007, P = 0.009, respectively). At 1 week and 3 months, although without statistical significance (P > 0.005), CRT, MV and MA also reduced in comparison to baseline.

Conclusions

Single intravitreal bevacizumab injection in eyes with neovascular AMD resulted in a substantial decrease of aqueous VEGF levels 1 week after treatment with the greatest improvement of clinical outcomes occurring at 1 month follow-up.

Encapsulated cells for long-term secretion of soluble VEGF receptor 1: Material optimization and simulation of ocular drug response

Anti-angiogenic therapies with vascular endothelial growth factor (VEGF) inhibiting factors are effective treatment options for neovascular diseases of the retina, but these proteins can only be delivered as intravitreal (IVT) injections. To sustain a therapeutic drug level in the retina, VEGF inhibitors have to be delivered frequently, every 4-8weeks, causing inconvenience for the patients and expenses for the healthcare system. The aim of this study was to investigate cell encapsulation as a delivery system for prolonged anti-angiogenic treatment of retinal neovascularization. Genetically engineered ARPE-19 cells secreting soluble vascular endothelial growth factor receptor 1 (sVEGFR1) were encapsulated in a hydrogel of cross-linked collagen and interpenetrating hyaluronic acid (HA). The system was optimized in terms of matrix composition and cell density, and long-term cell viability and protein secretion measurements were performed. sVEGFR1 ARPE-19 cells in the optimized hydrogel remained viable and secreted sVEGFR1 at a constant rate for at least 50days. Based on pharmacokinetic/pharmacodynamic (PK/PD) modeling, delivery of sVEGFR1 from this cell encapsulation system is expected to lead only to modest VEGF inhibition, but improvements of the protein structure and/or secretion rate should result in strong and prolonged therapeutic effect. In conclusion, the hydrogel matrix herein supported the survival and protein secretion from the encapsulated cells. The PK/PD simulation is a convenient approach to predict the efficiency of the cell encapsulation system before in vivo experiments.

Serum and plasma vascular endothelial growth factor concentrations before and after intravitreal injection of aflibercept or ranibizumab for age-related macular degeneration

PURPOSE

To evaluate serum and plasma vascular endothelial growth factor (VEGF) concentrations in neovascular age-related macular degeneration patients treated bimonthly with an intravitreal injection of aflibercept or ranibizumab.

DESIGN

Prospective, interventional case series.

METHODS

This study includes 17 eyes of 17 patients treated with 2 mg aflibercept (the aflibercept group), 15 eyes of 15 patients treated with 0.5 mg ranibizumab (the ranibizumab group), and 12 patients with cataract (the control group). Serum and plasma VEGF concentrations were quantified using the enzyme-linked immunosorbent assay.

RESULTS

At baseline, mean serum VEGF concentration (in picograms per milliliter) did not differ significantly among the 3 groups (P = .99). In the aflibercept group, it was 28.3 pg/mL at baseline, decreased to below the detectable limit at 1 week (P < .0001), increased to 11.7 pg/mL at 1 month, which was still significantly less than the baseline level (P < .001), and returned to 23.9 pg/mL (P = .35) at 2 months. In the ranibizumab group, there were no significant differences. At baseline, mean plasma VEGF concentration did not differ significantly among the 3 groups (P = .64). In the aflibercept group, it was 16.2 at baseline, decreased to less than the detectable limit at 1 week (P < .01) and at 1 month (P < .05), and returned to 13.6 pg/mL at 2 months (P = .73). In the ranibizumab group, there were no significant differences.

CONCLUSIONS

Aflibercept significantly decreased serum and plasma VEGF concentrations 1 month after injection; however, ranibizumab had no significant effect on either serum or plasma VEGF level.

VEGF-A polymorphisms predict short-term functional response to intravitreal ranibizumab in exudative age-related macular degeneration

AIM

To investigate the association between VEGF gene SNPs and early response to intravitreal ranibizumab for exudative age-related macular degeneration.

MATERIALS & METHODS

Sixty-four patients (64 eyes) were prospectively enrolled and treated for neovascular age-related macular degeneration with ranibizumab monotherapy. Visual acuity was measured using the ETDRS chart. A loading phase of 3 monthly intravitreal injections of ranibizumab 0.5 mg/0.05 ml was performed. The analyzed VEGF-A gene SNPs were rs699947 (-2578A/C) and rs1570360 (-1154G/A); the allelic discrimination was performed in real-time PCR platform. The difference of best corrected visual acuity (ETDRS letters) read before and after treatment was considered as functional outcome.

RESULTS

Ranibizumab was significantly more effective as measured by best corrected visual acuity in patients harboring the VEGF-A -2578C allele (from +6.26 to +7.44 ETDRS letters), whereas patients carrying the VEGF-A -2578AA genotype revealed an absence of early functional response to ranibizumab (-1.78 ETDRS letters; p = 0.0192).

CONCLUSION

This study suggests that the VEGF-A -2578A/C SNP may represent an important molecular determinant of the early functional outcome of ranibizumab. Original submitted 3 December 2012; Revision submitted 18 February 2013.

Pharmacokinetics, pharmacodynamics and pre-clinical characteristics of ophthalmic drugs that bind VEGF

Drugs that prevent the binding of VEGF to its trans-membrane cognate receptors have revolutionized the treatment of the most important chorioretinal vascular disorders: exudative age-related macular degeneration, diabetic macular edema, and retinal vein occlusions. Pegaptanib, which binds to VEGF165 and longer isoforms, ranibizumab and bevacizumab, which bind all VEGF-A isoforms, and aflibercept, which binds VEGF-A, VEGF-B, and placental growth factor, all bind VEGF165 with high affinity. The drugs have relatively long half-lives (7 to 10 days) after intravitreal depot injections and clinical durations of action that usually exceed 4 weeks. Plasma VEGF concentrations decrease after intravitreal injections of bevacizumab and aflibercept because their systemic half-lives are extended by their Fc fragments. Extensive in vitro and in vivo testing shows that the drugs prevent VEGF-mediated activation of endothelial cells while exhibiting little evidence of toxicity. Further anti-VEGF drug development is on-going.

Proteomic interactions in the mouse vitreous-retina complex

PURPOSE

Human vitreoretinal diseases are due to presumed abnormal mechanical interactions between the vitreous and retina, and translational models are limited. This study determined whether nonstructural proteins and potential retinal biomarkers were expressed by the normal mouse vitreous and retina.

METHODS

Vitreous and retina samples from mice were collected by evisceration and analyzed by liquid chromatography-tandem mass spectrometry. Identified proteins were further analyzed for differential expression and functional interactions using bioinformatic software.

RESULTS

We identified 1,680 unique proteins in the retina and 675 unique proteins in the vitreous. Unbiased clustering identified protein pathways that distinguish retina from vitreous including oxidative phosphorylation and neurofilament cytoskeletal remodeling, whereas the vitreous expressed oxidative stress and innate immunology pathways. Some intracellular protein pathways were found in both retina and vitreous, such as glycolysis and gluconeogenesis and neuronal signaling, suggesting proteins might be shuttled between the retina and vitreous. We also identified human disease biomarkers represented in the mouse vitreous and retina, including carbonic anhydrase-2 and 3, crystallins, macrophage inhibitory factor, glutathione peroxidase, peroxiredoxins, S100 precursors, and von Willebrand factor.

CONCLUSIONS

Our analysis suggests the vitreous expresses nonstructural proteins that functionally interact with the retina to manage oxidative stress, immune reactions, and intracellular proteins may be exchanged between the retina and vitreous. This novel proteomic dataset can be used for investigating human vitreoretinopathies in mouse models. Validation of vitreoretinal biomarkers for human ocular diseases will provide a critical tool for diagnostics and an avenue for therapeutics.

Silibinin inhibits VEGF secretion and age-related macular degeneration in a hypoxia-dependent manner through the PI-3 kinase/Akt/mTOR pathway

BACKGROUND AND PURPOSE

Hypoxia-mediated neovascularization plays an important role in age-related macular degeneration (AMD). There are few animal models or effective treatments for AMD. Here, we investigated the effects of the flavonoid silibinin on hypoxia-induced angiogenesis in a rat AMD model.

EXPERIMENTAL APPROACH

Retinal pigmented epithelial (RPE) cells were subjected to hypoxia in vitro and the effects of silibinin on activation of key hypoxia-induced pathways were examined by elucidating the hypoxia-inducible factor-1 alpha (HIF-1α) protein level by Western blot. A rat model of AMD was developed by intravitreal injection of VEGF in Brown Norway rats, with or without concomitant exposure of animals to hypoxia. Animals were treated with oral silibinin starting at day 7 post-VEGF injection and AMD changes were followed by fluorescein angiography on days 14 and 28 post-injection.

KEY RESULTS

Silibinin pretreatment of RPE cells increased proline hydroxylase-2 expression, inhibited HIF-1α subunit accumulation, and inhibited VEGF secretion. Silibinin-induced HIF-1α and VEGF down-regulation required suppression of hypoxia-induced phosphatidylinositol 3-kinase/Akt/mammalian target of rapamycin (mTOR) pathway. In the rat model of AMD, silibinin administration prevented VEGF- and VEGF plus hypoxia-induced retinal oedema and neovascularization.

CONCLUSION AND IMPLICATIONS

The effects of silibinin, both in vitro and in vivo, support its potential as a therapeutic for the prevention of neovascular AMD.

Preclinical aspects of anti-VEGF agents for the treatment of wet AMD: ranibizumab and bevacizumab

Three anti-vascular endothelial growth factor (VEGF) therapies are currently used for the treatment of patients with wet age-related macular degeneration (AMD): pegaptanib, ranibizumab, and bevacizumab. Ranibizumab is an antibody fragment approved for the treatment of wet AMD. Bevacizumab is a full-length antibody registered for use in oncology but unlicensed for wet AMD. However, it is used off-label worldwide not only for wet AMD but also for various other ocular diseases associated with macular edema and abnormal vessel growth. We consider aspects of ranibizumab and bevacizumab in relation to their molecular characteristics, in vitro and in vivo properties, and preclinical safety data. Before 2009, most studies described the short-term toxicity of bevacizumab in multiple cell types of the eye. Since 2009, an increasing number of studies have compared the properties of ranibizumab and bevacizumab and investigated their impact on retinal cell functioning. Compared with bevacizumab, ranibizumab neutralizes VEGF better at low concentrations, maintains efficacy for longer, and has a higher retinal penetration and potency. Studies in animals demonstrate ranibizumab to be better localized to the injected eye, whereas bevacizumab appears to have a greater effect in the fellow eye. In humans, a localized and systemic effect has been reported for both molecules. In conclusion, overlapping yet distinct pharmacological properties of ranibizumab and bevacizumab indicate that safety or efficacy data from one cannot be extrapolated to the other.