Development of Anti-VEGF Therapies for Intraocular Use: A Guide for Clinicians

Topical Solution for Retinal Delivery: Bevacizumab and Ranibizumab Eye Drops in Anti-Aggregation Formula (AAF) in Rabbits

PURPOSE

Wet age-related macular degeneration (AMD) is a blinding retinal disease. Monthly intravitreal anti-VEGF antibody injections of bevacizumab (off-label) and ranibizumab (FDA approved) are the standard of care. Antibody aggregation may interfere with ocular absorption/distribution. This study assessed topical delivery of dilute antibodies to the posterior segment of rabbit eyes using a novel anti-aggregation formula (AAF).

METHODS

Bevacizumab, or biosimilar ranibizumab was diluted to 5 mg/ml in AAF. All rabbits were dosed twice daily. Substudy 1 rabbits (bevacizumab, 100 µl eye drops): Group 1 (bevacizumab/AAF, n = 6); Group 2 (bevacizumab/PBS, n = 7) and Vehicle control (AAF, n = 1). Substudy 2 rabbits (ranibizumab biosimilar/AAF, 50 µl eye drops): (ranibizumab biosimilar/AAF, n = 8). At 14.5 days, serum was drawn from rabbits. Aqueous, vitreous and retina samples were recovered from eyes and placed into AAF aliquots. Tissue analyzed using AAF as diluent.

RESULTS

Bevacizumab in AAF permeated/accumulated in rabbit aqueous, vitreous and retina 10 times more, than when diluted in PBS. AAF/0.1% hyaluronic acid eye drops, dosed twice daily, provided mean tissue concentrations (ng/g) in retina (29.50), aqueous (12.34), vitreous (3.46), and serum (0.28 ng/ml). Additionally, the highest concentration (ng/g) of ranibizumab biosimilar was present in the retina (18.0), followed by aqueous (7.82) and vitreous (1.47). Serum concentration was negligible (< 0.04 ng/ml). No irritation was observed throughout the studies.

CONCLUSIONS

Bevacizumab and ranibizumab, in an AAF diluent eye drop, can be delivered to the retina, by the twice daily dosing of a low concentration mAb formulation. This may prove to be an adjunct to intravitreal injections.

Wound Modulations in Glaucoma Surgery: A Systematic Review

Excessive fibrosis and resultant poor control of intraocular pressure (IOP) reduce the efficacy of glaucoma surgeries. Historically, corticosteroids and anti-fibrotic agents, such as mitomycin C (MMC) and 5-fluorouracil (5-FU), have been used to mitigate post-surgical fibrosis, but these have unpredictable outcomes. Therefore, there is a need to develop novel treatments which provide increased effectiveness and specificity. This review aims to provide insight into the pathophysiology behind wound healing in glaucoma surgery, as well as the current and promising future wound healing agents that are less toxic and may provide better IOP control.

Resvega, a Nutraceutical Preparation, Affects NFκB Pathway and Prolongs the Anti-VEGF Effect of Bevacizumab in Undifferentiated ARPE-19 Retina Cells

Age-related macular degeneration (AMD) is an irreversible chronic degenerative pathology that affects the retina. Despite therapeutic advances thanks to the use of anti-vascular endothelial growth factor (VEGF) agents, resistance mechanisms have been found to accentuate the visual deficit. In the present study, we explored whether a nutraceutical formulation composed of omega-3 fatty acids and resveratrol, called Resvega®, was able to disrupt VEGF-A secretion in human ARPE-19 retina cells. We found that Resvega® inhibits VEGF-A secretion through decreases in both the PI3K-AKT-mTOR and NFκB signaling pathways. In NFκB signaling pathways, Resvega® inhibits the phosphorylation of the inhibitor of NFκB, IκB, which can bind NFκB dimers and sequester them in the cytoplasm. Thus, the NFκB subunits cannot migrate to the nucleus where they normally bind and stimulate the transcription of target genes such as VEGF-A. The IκB kinase complex (IKK) is also affected by Resvega® since the nutraceutical formulation decreases both IKKα and IKKβ subunits and the IKKγ subunit which is required for the stimulation of IKK. Very interestingly, we highlight that Resvega® could prolong the anti-angiogenic effect of Avastin®, which is an anti-VEGF agent typically used in clinical practice. Our results suggest that Resvega® may have potential interest as nutritional supplementation against AMD.

TGF-β Superfamily Signaling in the Eye: Implications for Ocular Pathologies

The TGF-β signaling pathway plays a crucial role in several key aspects of development and tissue homeostasis. TGF-β ligands and their mediators have been shown to be important regulators of ocular physiology and their dysregulation has been described in several eye pathologies. TGF-β signaling participates in regulating several key developmental processes in the eye, including angiogenesis and neurogenesis. Inadequate TGF-β signaling has been associated with defective angiogenesis, vascular barrier function, unfavorable inflammatory responses, and tissue fibrosis. In addition, experimental models of corneal neovascularization, diabetic retinopathy, proliferative vitreoretinopathy, glaucoma, or corneal injury suggest that aberrant TGF-β signaling may contribute to the pathological features of these conditions, showing the potential of modulating TGF-β signaling to treat eye diseases. This review highlights the key roles of TGF-β family members in ocular physiology and in eye diseases, and reviews approaches targeting the TGF-β signaling as potential treatment options.

Hyaluronic Acid-PEG-Based Diels-Alder In Situ Forming Hydrogels for Sustained Intraocular Delivery of Bevacizumab

Retinal diseases are the leading cause of visual impairment worldwide. The effectiveness of antibodies for the treatment of retinal diseases has been demonstrated. Despite the clinical success, achieving sufficiently high concentrations of these protein therapeutics at the target tissue for an extended period is challenging. Patients suffering from macular degeneration often receive injections once per month. Therefore, there is a growing need for suitable systems that can help reduce the number of injections and adverse effects while improving patient complacency. This study systematically characterized degradable "in situ" forming hydrogels that can be easily injected into the vitreous cavity using a small needle (29G). After intravitreal injection, the formulation is designed to undergo a sol-gel phase transition at the administration site to obtain an intraocular depot system for long-term sustained release of bioactives. A Diels-Alder reaction was exploited to crosslink hyaluronic acid-bearing furan groups (HAFU) with 4 arm-PEG10K-maleimide (4APM), yielding stable hydrogels. Here, a systematic investigation of the effects of polymer composition and the ratio between functional groups on the physicochemical properties of hydrogels was performed to select the most suitable formulation for protein delivery. Rheological analysis showed rapid hydrogel formation, with the fastest gel formation within 5 min after mixing the hydrogel precursors. In this study, the mechanical properties of an ex vivo intravitreally formed hydrogel were investigated and compared to the in vitro fabricated samples. Swelling and degradation studies showed that the hydrogels are biodegradable by the retro-Diels-Alder reaction under physiological conditions. The 4APM-HAFU (ratio 1:5) hydrogel formulation showed sustained release of bevacizumab > 400 days by a combination of diffusion, swelling, and degradation. A bioassay showed that the released bevacizumab remained bioactive. The hydrogel platform described in this study offers high potential for the sustained release of therapeutic antibodies to treat ocular diseases.

Impact of Delayed Intravitreal Anti-Vascular Endothelial Growth Factor (VEGF) Therapy Due to the Coronavirus Disease Pandemic on the Prognosis of Patients with Neovascular Age-Related Macular Degeneration

This study estimated the outcome of delayed intravitreal anti-vascular endothelial growth factor (VEGF) therapy due to the coronavirus (COVID-19) disease pandemic on the prognosis of patients with neovascular age-related macular degeneration (nAMD). This study retrospectively enrolled 57 nAMD patients whose intravitreal anti-VEGF injections were delayed for >2 weeks between February and June 2020. Best-corrected visual acuity (BCVA), central subfield thickness (CST), and anatomical characteristics were evaluated before (baseline), on the day, and at 2, 4, and 6 months after the delayed injection, and risk factors were identified. The average injection interval before and after treatment delay was 3.05 ± 1.45 and 2.41 ± 1.46 months, respectively (p = 0.002). The CST at baseline and on the day of delayed injection was 227.82 ± 62.46 and 267.26 ± 77.74 µm, respectively (p < 0.001). The average BCVA decreased from 0.29 ± 0.29 logMAR (baseline) to 0.38 ± 0.31 logMAR (6 months) (p = 0.001). The maximum subretinal fluid (SRF) height increased from 84.32 ± 89.33 µm (baseline) to 121.38 ± 103.36 µm (6 months) (p = 0.027). A higher baseline maximum SRF height was associated with less SRF height deterioration 6 months later (p < 0.001). Delayed intravitreal anti-VEGF therapy caused by the COVID-19 pandemic has worsened BCVA and residual SRF in nAMD patients after a temporary recovery. The baseline SRF reduce the degree of SRF height deterioration.

Vitreous function and intervention of it with vitrectomy and other modalities

The vitreous body, the largest intraocular component, plays a key role in eye development, refraction, cell barrier function, oxygen metabolism and the pathogenesis of assorted diseases. Age, refraction and systemic diseases can cause vitreous metabolic abnormalities. With the continuous development of vitrectomy techniques and equipment, vitreous injections and vitrectomies have increased over the recent decades. However, the normal oxygen tension gradient in the vitreous helps to protect the lens and anterior chamber angle from oxidative stress damage, whereas the increased vitreous oxygen tension around lens and the trabecular meshwork after vitrectomy may lead to postoperative nuclear cataract and a high incidence of open angle glaucoma. As a conventional procedure, scleral buckling holds several advantages over vitrectomy in selected cases. This review raises concerns regarding the function of the vitreous, and encourages conducting vitreous interventions prudently.

RESVEGA, a Nutraceutical Omega-3/Resveratrol Supplementation, Reduces Angiogenesis in a Preclinical Mouse Model of Choroidal Neovascularization

Age-related macular degeneration (AMD) is an eye disease that is characterized by damage to the central part of the retina, the macula, and that affects millions of people worldwide. At an advanced stage, a blind spot grows in the center of vision, severely handicapping patients with this degenerative condition. Despite therapeutic advances thanks to the use of anti-VEGF, many resistance mechanisms have been found to accentuate the visual deficit. In the present study, we explored whether supplementation with Resvega^®, a nutraceutical formulation composed of omega-3 fatty acids and resveratrol, a well-known polyphenol in grapes, was able to counteract laser-induced choroidal neovascularization (CNV) in mice. We highlight that Resvega^® significantly reduced CNV in mice compared with supplementations containing omega-3 or resveratrol alone. Moreover, a proteomic approach confirmed that Resvega^® could counteract the progression of AMD through a pleiotropic effect targeting key regulators of neoangiogenesis in retina cells in vivo. These events were associated with an accumulation of resveratrol metabolites within the retina. Therefore, a supplementation of omega-3/resveratrol could improve the management or slow the progression of AMD in patients with this condition.

Choroidal structural changes determined by the binarization method after intravitreal aflibercept treatment in neovascular age-related macular degeneration

AIM

To assess the choroidal structural alterations after intravitreal injection of aflibercept in neovascular age-related macular degeneration (nAMD).

METHODS

Fifty eyes with treatment-naïve nAMD were evaluated at baseline, 3^rd, and 12^th month. Fifty eyes of 50 healthy subjects were also included as controls. Choroidal thickness (CT) was measured in the subfoveal region. Total circumscribed choroidal area (CA), luminal area (LA), stromal area (SA), and choroidal vascularity index (CVI) was calculated using Image J.

RESULTS

At baseline, subfoveal CT was increased in nAMD patients compared to controls (P=0.321). Eyes with nAMD had a significantly increased total circumscribed CA and SA (P=0.041, 0.005, respectively). The CVI was decreased (P=0.038). In the 3^rd month, the subfoveal CT, LA, and CVI revealed a decrease (P=0.005, P=0.039, 0.043, respectively). In the 12^th month, subfoveal CT, LA, and CVI were decreased in comparison to baseline measures (P<0.001, 0.006, 0.010, respectively).

CONCLUSION

Significant structural alterations are found after intravitreal aflibercept treatment during the 12-month follow-up, in particular at the third month, in eyes with nAMD.

Treatment Landscape of Macular Disorders in Indian Patients with the Advent of Razumab™ (World's First Biosimilar Ranibizumab): A Comprehensive Review

Ranibizumab is approved for the treatment of several macular disorders, including wet age-related macular degeneration (wet AMD), diabetic macular edema (DME), retinal vein occlusion (RVO) and myopic choroidal neovascularization (mCNV), among others. The unaffordability of the innovator ranibizumab among patients from developing countries such as India led to the development of the world’s first biosimilar ranibizumab, which is a cost-effective alternative that does not compromise efficacy and safety. Razumab™, developed and produced by Intas Pharmaceuticals Ltd., India, is the world’s first biosimilar of ranibizumab, and is approved in India for the treatment of various macular disorders, including wet AMD, DME, RVO and mCNV. The efficacy and safety of Razumab for the treatment of these macular disorders have been evaluated in both prospective and real-world retrospective studies. Razumab has shown an efficacy similar to that of the innovator ranibizumab, achieving improved visual acuity, as measured by the best corrected visual acuity, and reduction in the central macular thickness, leading to improved patient outcomes. The safety profile of Razumab is comparable to that of the innovator ranibizumab and is well tolerated without any new safety concerns. Here, we review the clinical and real-world data of Razumab in the treatment of macular disorders.

VEGF-R2/Caveolin-1 Pathway of Undifferentiated ARPE-19 Retina Cells: A Potential Target as Anti-VEGF-A Therapy in Wet AMD by Resvega, an Omega-3/Polyphenol Combination

Age-related macular degeneration (AMD) is one of the main causes of deterioration in vision in adults aged 55 and older. In spite of therapies, the progression of the disease is often observed without reverse vision quality. In the present study, we explored whether, in undifferentiated ARPE-19 retinal cells, a disruption of the VEGF receptors (VEGF-R)/caveolin-1 (Cav-1)/protein kinases pathway could be a target for counteracting VEGF secretion. We highlight that Resvega^®, a combination of omega-3 fatty acids with an antioxidant, resveratrol, inhibits VEGF-A secretion in vitro by disrupting the dissociation of the VEGF-R2/Cav-1 complex into rafts and subsequently preventing MAPK activation. Moreover, DNA ChIP analysis reveals that this combination prevents the interaction between AP-1 and vegf-a and vegf-r2 gene promoters. By these pathways, Resvega could present a potential interest as nutritional complementation against AMD.

The COVID-19 Pandemic Has Had Negative Effects on Baseline Clinical Presentation and Outcomes of Patients with Newly Diagnosed Treatment-Naïve Exudative AMD

PURPOSE

To investigate whether the coronavirus disease 2019 (COVID-19) pandemic-associated postponement in care had effects on the baseline clinical presentation of patients with newly diagnosed treatment-naïve exudative neovascular age-related macular degeneration (AMD).

METHODS

We included the first 50 consecutive patients referred within the COVID-19 pandemic with a diagnosis of treatment-naïve exudative neovascular AMD. Two groups of fifty consecutive patients with newly diagnosed neovascular exudative AMD presenting in 2018 and 2019 (control periods) were also included for comparisons.

RESULTS

Baseline visual acuity was statistically worse in patients referred during the COVID-19 pandemic period (0.87 ± 0.51 logarithm of the minimum angle of resolution (LogMAR)) as compared with both the "2019" (0.67 ± 0.48 LogMAR, p = 0.001) and "2018" (0.69 ± 0.54 LogMAR, p = 0.012) control periods. Data on the visual function after a loading dose of anti-vascular endothelial growth factor (VEGF) was available in a subset of patients (43 subjects in 2020, 45 in 2019 and 46 in 2018, respectively). Mean ± SD best corrected visual acuity (BCVA) at the 1-month follow-up visit after the third anti-VEGF injection was still worse in patients referred during the COVID-19 pandemic (0.82 ± 0.66 LogMAR) as compared with both the "2019" (0.60 ± 0.45 LogMAR, p = 0.021) and "2018" (0.55 ± 0.53 LogMAR, p = 0.001) control periods. On structural optical coherence tomography (OCT), the maximum subretinal hyperreflective material (SHRM) height and width were significantly greater in the COVID-19 pandemic patients.

CONCLUSIONS

We demonstrated that patients with newly diagnosed treatment-naïve exudative neovascular AMD referred during the COVID-19 pandemic had worse clinical characteristics at presentation and short-term visual outcomes.

Short-term outcomes of patients with neovascular exudative AMD: the effect of COVID-19 pandemic

PURPOSE

To estimate the impact of delayed care during the coronavirus disease 2019 (COVID-19) pandemic on the outcomes of patients with neovascular age-related macular degeneration (AMD).

METHODS

Consecutive patients with diagnosis of neovascular AMD were consecutively enrolled between March 9, 2020, and June 12, 2020, (during and immediately after the Italian COVID-19 quarantine). During the inclusion (or pandemic) visit (V₀), patients received a complete ophthalmologic evaluation, including optical coherence tomography (OCT). Best-corrected visual acuity (BCVA) and OCT findings from the two preceding visits (V_-1 and V_-2) were compared with data at V₀.

RESULTS

One-hundred patients (112 eyes) were enrolled in this study. The time interval between following visits was 110.7 ± 37.5 days within V₀ and V_-1 and 80.8 ± 39.7 days within V_-1 and V_-2, respectively (P < 0.0001). BCVA was statistically worse at the V₀ visit as compared with the immediately preceding (V_-1) visit (0.50 ± 0.43 LogMAR and 0.45 ± 0.38 LogMAR at the V₀ and V_-1 visits, respectively; P = 0.046). On structural OCT, 91 out of 112 (81.2%) neovascular AMD eyes displayed the evidence of exudative disease activity at the V₀ visit, while 77 (68.7%) eyes exhibited signs of exudation at the V_-1 visit (P = 0.022). No differences in terms of BCVA and OCT findings were detected between the V_-1 and V_-2 visits. In multiple regression analysis, the difference in BCVA between V₀ and V_-1 visits was significantly associated with the interval time within these two visits (P = 0.026).

CONCLUSION

The COVID-19 pandemic-related postponement in patient care proved to be significantly associated with worse short-term outcomes in these patients.

Salidroside improves angiogenesis-osteogenesis coupling by regulating the HIF-1α/VEGF signalling pathway in the bone environment

Angiogenesis is essential for bone formation during skeletal development. HIF-1α and the HIF-responsive gene VEGF (vascular endothelial growth factor) are reported to be a key mechanism for coupling osteogenesis and angiogenesis. Salidroside (SAL), a major biologically active compound of Rhodiola rosea L., possesses diverse pharmacological effects. However, whether SAL can protect against bone loss via the HIF-1α/VEGF pathway, specifically by inducing angiogenesis-osteogenesis coupling in vivo, remains unknown. Therefore, in the present study, we employed primary human umbilical vein endothelial cells (HUVECs) and the permanent EA.hy926 human endothelial cell line to determine the cellular and molecular effects of SAL on vascular endothelial cells and the HIF-1α-VEGF signalling pathway in the coupling of angiogenesis-osteogenesis. The in vitro study revealed that the HUVECs and EA.hy926 cells treated with conditioned medium from osteoblast cells (MG-63 cells) treated with SAL or treated directly with SAL showed enhanced proliferation, migration and capillary structure formation. However, supplementation with an anti-VEGF antibody during the treatment of endothelial cells (ECs) significantly reversed the pro-angiogenic effect of SAL. Moreover, SAL upregulated HIF-1α expression and increased its transcriptional activity, consequently upregulating VEGF expression at the mRNA and protein levels. In addition, our in vivo analysis demonstrated that SAL can stimulate endothelial sprouting from metatarsal bones. Thus, our mechanistic study demonstrated that the pro-angiogenic effects of SAL involve HIF-1α-VEGF signalling by coordinating the coupling of angiogenesis-osteogenesis in the bone environment. Therefore, we have discovered an ideal molecule that simultaneously enhances angiogenesis and osteogenesis and thereby accelerates bone healing.

Intravitreal hydrogels for sustained release of therapeutic proteins

This review highlights how hydrogel formulations can improve intravitreal protein delivery to the posterior segment of the eye in order to increase therapeutic outcome and patient compliance. Several therapeutic proteins have shown excellent clinical successes for the treatment of various intraocular diseases. However, drug delivery to the posterior segment of the eye faces significant challenges due to multiple physiological barriers preventing drugs from reaching the retina, among which intravitreal protein instability and rapid clearance from the site of injection. Hence, frequent injections are required to maintain therapeutic levels. Moreover, because the world population ages, the number of patients suffering from ocular diseases, such as age-related macular degeneration (AMD) and diabetic retinopathy (DR) is increasing and causing increased health care costs. Therefore, there is a growing need for suitable delivery systems able to tackle the current limitations in retinal protein delivery, which also may reduce costs. Hydrogels have shown to be promising delivery systems capable of sustaining release of therapeutic proteins and thus extending their local presence. Here, an extensive overview of preclinically developed intravitreal hydrogels is provided with attention to the rational design of clinically useful intravitreal systems. The currently used polymers, crosslinking mechanisms, in vitro/in vivo models and advancements are discussed together with the limitations and future perspective of these biomaterials.

Antagonist of nucleolin, N6L, inhibits neovascularization in mouse models of retinopathies

Retinal vascular diseases (RVD) have been identified as a major cause of blindness worldwide. These pathologies, including the wet form of age-related macular degeneration, retinopathy of prematurity, and diabetic retinopathy are currently treated by intravitreal delivery of anti-vascular endothelial growth factor (VEGF) agents. However, repeated intravitreal injections can lead to ocular complications and resistance to these treatments. Thus, there is a need to find new targeted therapies. Nucleolin regulates the endothelial cell (EC) activation and angiogenesis. In previous studies, we designed a pseudopeptide, N6L, that binds the nucleolin and blocks the tumor angiogenesis. In this study, the effect of N6L was investigated in two experimental models of retinopathies including oxygen-induced retinopathy (OIR) and choroidal neovascularization (CNV). We found that in mouse OIR, intraperitoneal injection of N6L is delivered to activated ECs and induced a 50% reduction of pathological neovascularization. The anti-angiogenic effect of N6L has been tested in CNV model in which the systemic injection of N6L induced a 33% reduction of angiogenesis. This effect is comparable to those obtained with VEGF-trap, a standard of care drug for RVD. Interestingly, with preventive and curative treatments, neoangiogenesis is inhibited by 59%. Our results have potential interest in the development of new therapies targeting other molecules than VEGF for RVD.

Restoring retinal neurovascular health via substance P

Regulation of vascular permeability plays a major role in the pathophysiology of visually threatening conditions such as retinal vein occlusion and diabetic retinopathy. Principally, several factors such as vascular endothelial growth factor (VEGF), are up-regulated or induced in response to hypoxia thus adversely affecting the blood-retinal barrier (BRB), resulting in retinal edema and neovascularisation. Furthermore, current evidence supports a dysregulation of the inner retinal neural-vascular integrity as a critical factor driving retinal ganglion cell (RGC) death and visual loss. The principal objective of this study was to interrogate whether Substance P (SP), a constitutive neurotransmitter of amacrine and ganglion cells, may protect against N-methyl-d-aspartate (NMDA)-induced excitotoxic apoptosis of ganglion cells and VEGF-induced vessel leakage in the retina. Tight junctional protein expression and a Vascular Permeability Image Assay were used to determine vascular integrity in vitro. The protective effect of SP on RGC was established in ex vivo retinal explants and in vivo murine models. After NMDA administration, a reduction in TUNEL+ cells and a maintained number of Brn-3a+ cells were found, indicating an inhibition of RGC apoptosis mediated by SP. Additionally, SP maintained endothelial tight junctions and decreased VEGF-induced vascular permeability. In conclusion, administration of SP protects against NMDA apoptosis of RGC and VEGF-induced endothelial barrier breakdown.

Photokinetic Drug Delivery: Near infrared (NIR) Induced Permeation Enhancement of Bevacizumab, Ranibizumab and Aflibercept through Human Sclera

PURPOSE

Permeation studies, with near infrared (NIR) light and anti-aggregation antibody formulation, were used to investigate the in vitro permeation of bevacizumab, ranibizumab and aflibercept through human sclera.

METHODS

A vertical, spherical Franz cell diffusion apparatus was used for this scleral tissue permeation model. A photokinetic ocular drug delivery (PODD) testing device accommodated the placement of NIR LEDs above the donor chambers. An adjustable LED driver/square wave generator provided electrical energy with a variable pulse rate and pulse width modulation (duty cycle).

RESULTS

Exposure to non-thermal NIR light had no effect on mAbs with regard to monomer concentration or antibody binding potential, as determined by SE-HPLC and ELISA. The optimal LED wavelength was found to be 950 nm. Duty cycle power of 5% vs 20% showed no difference in permeation. When compared to controls, the combination of non-aggregating antibody formulation and NIR illumination provided an average transscleral drug flux enhancement factor of 3X.

CONCLUSION

Narrow wavelength incoherent (non-laser) light from an NIR LED source is not harmful to mAbs and can be used to enhance drug permeation through scleral tissue. The topical formulation, combined with pulsed NIR light irradiation, significantly improved scleral permeation of three anti-VEGF antibody drugs.

A2E-associated cell death and inflammation in retinal pigmented epithelial cells from human induced pluripotent stem cells

Accumulation of lipofuscin in the retinal pigmented epithelium (RPE) is observed in retinal degenerative diseases including Stargardt disease and age-related macular degeneration. Bis-retinoid N-retinyl-N-retinylidene ethanolamine (A2E) is a major component of lipofuscin. A2E has been implicated in RPE atrophy and retinal inflammation; however, mice with A2E accumulation display only a mild retinal phenotype. In the current study, human iPSC-RPE (hiPSC-RPE) cells were generated from healthy individuals to examine effects of A2E in human RPE cells. hiPSC-RPE cells displayed RPE-specific features, which include expression of RPE-specific genes, tight junction formation and ability to carry out phagocytosis. hiPSC-RPE cells demonstrated cell death and increased VEGF-A production in a time-dependent manner when they were cocultured with 10 μM of A2E. PCR array analyses revealed upregulation of 26 and 12 pro-inflammatory cytokines upon A2E and H₂O₂ exposure respectively, indicating that A2E and H₂O₂ can cause inflammation in human retinas. Notably, identified gene profiles were different between A2E- and H₂O₂-treated hiPSC-RPE cells. A2E caused inflammatory changes observed in retinal degenerative diseases more closely as compared to H₂O₂. Collectively, these data obtained with hiPSC-RPE cells provide evidence that A2E plays an important role in pathogenesis of retinal degenerative diseases in humans.

TGF-β participates choroid neovascularization through Smad2/3-VEGF/TNF-α signaling in mice with Laser-induced wet age-related macular degeneration

Choroidal neovascularization(CNV) is the most severe complication in Age-related macular degeneration(AMD) and the most common cause of irreversible blindness in the elderly in developed world. The aim of this study was to identify the effect of transforming growth factor-β(TGF-β) and Smad2/3-VEGF/TNF-α signaling on CNV angiopoiesis, and to explore TGF-β inhibitors on the development of CNV in a CNV mouse model. Fundus fluorescein angiography(FFA) was used to evaluate the laser-induced CNV formation. The histology of CNV lesions stained with hematoxylin-eosin(HE) was obtained. The immunofluorescent staining was performed to determine TGF-β protein expression. The expressions of TGF-β, phosphorylated Smad2/3, VEGF and TNF-α were determined by using Western blot analysis. The CNV areas were analyzed by using fluorescein stain on RPE/choroid-sclera flat mounts. We found the levels of TGF-β protein expression increasingly reached the peak till 3rd week during the CNV development. The protein levels of VEGF and TNF-α also increased significantly in CNV mice, which were inhibited by a synthetic TGF-β inhibitor LY2157299 or a natural TGF-β inhibitor Decorin. The phosphorylated Smad2/3 levels increased significantly in CNV mice, but this response was profoundly suppressed by the TGF-β inhibitors. Here we have demonstrated that TGF-β/Smad signaling plays an important role in Laser-induced CNV formation through down-regulation of VEGF and TNF-α expressions, suggesting TGF-β inhibitors may provide an alternative to traditional methods in wet AMD treatment.

Adeno-associated virus mediated delivery of an engineered protein that combines the complement inhibitory properties of CD46, CD55 and CD59

BACKGROUND

A variety of disorders are associated with the activation of complement. CD46, CD55 and CD59 are the major membrane associated regulators of complement on human cells. Previously, we have found that independent expression of CD55, CD46 or CD59 through gene transfer protects murine tissues against human complement mediated attack. In the present study, we investigated the potential of combining the complement regulatory properties of CD46, CD55 and CD59 into single gene products expressed from an adeno-associated virus (AAV) vector in a soluble non-membrane anchored form.

METHODS

Minigenes encoding the complement regulatory domains from CD46, CD55 and CD59 (SACT) or CD55 and CD59 (DTAC) were cloned into an AAV vector. The specific regulatory activity of each component of SACT and DTAC was measured in vitro. The recombinant AAV vectors were injected into the peritoneum of mice and the efficacy of the transgene products for being able to protect murine liver vasculature against human complement, specifically the membrane attack complex (MAC), was measured.

RESULTS

SACT and DTAC exhibited properties similar to CD46, CD55 and CD59 or CD55 and CD59, respectively, in vitro. AAV mediated delivery of SACT or DTAC protected murine liver vasculature from human MAC deposition by 63.2% and 56.7%, respectively.

CONCLUSIONS

When delivered to mice in vivo via an AAV vector, SACT and DTAC are capable of limiting human complement mediated damage. SACT and DTAC merit further study as potential therapies for complement mediated disorders when delivered via a gene therapy approach.

Differential regulation of angiogenesis using degradable VEGF-binding microspheres

Vascular endothelial growth factor (VEGF) spatial and temporal activity must be tightly controlled during angiogenesis to form perfusable vasculature in a healing wound. The native extracellular matrix (ECM) regulates growth factor activity locally via sequestering, and researchers have used ECM-mimicking approaches to regulate the activity of VEGF in cell culture and in vivo. However, the impact of dynamic, affinity-mediated growth factor sequestering has not been explored in detail with biomaterials. Here, we sought to modulate VEGF activity dynamically over time using poly(ethylene glycol) microspheres containing VEGF-binding peptides (VBPs) and exhibiting varying degradation rates. The degradation rate of VBP microspheres conferred a differential ability to up- or down-regulate VEGF activity in culture with primary human endothelial cells. VBP microspheres with fast-degrading crosslinks reduced VEGF activity and signaling, while VBP microspheres with no inherent degradability sequestered and promoted VEGF activity in culture with endothelial cells. VBP microspheres with degradable crosslinks significantly reduced neovascularization in vivo, but neither non-degradable VBP microspheres nor bolus delivery of soluble VBP reduced neovascularization. The covalent incorporation of VBP to degradable microspheres was required to reduce neovascularization in a mouse model of choroidal neovascularization in vivo, which demonstrates a potential clinical application of degradable VBP microspheres to reduce pathological angiogenesis. The results herein highlight the ability to modulate the activity of a sequestered growth factor by changing the crosslinker identity within PEG hydrogel microspheres. The insights gained here may instruct the design and translation of affinity-based growth factor sequestering biomaterials for regenerative medicine applications.

Composite Nanoformulation Therapeutics for Long-Term Ocular Delivery of Macromolecules

The purpose of this investigation is to design and synthesize novel pentablock (PB) copolymer (PB-1: PCL-PLA-PEG-PLA-PCL) based nanoformulations suspended in a thermosensitive gelling copolymer (PB-2: mPEG-PCL-PLA-PCL-PEGm) termed as composite nanoformulation. The composite nanoformulation was prepared to provide a sustained delivery of macromolecules over a longer duration with negligible burst release effect. The delivery system was designed to be utilized for the treatment of posterior segment ocular diseases such as age-related (wet) macular degeneration, diabetic retinopathy, and diabetic macular edema. The novel PB copolymers were characterized for their functional groups by Fourier transform infrared spectroscopy, molecular weight and purity by (1)H NMR spectroscopy, and gel permeation chromatography. X-ray diffraction analysis was used to determine the crystallinity of copolymers. The size distribution of PB-1 nanoparticles (NPs) prepared using emulsification-solvent evaporation method was found to be ∼150 nm analyzed by nanoparticle tracking analysis. The % encapsulation efficiency and % drug loading were found to be 66.64% w/w ± 1.75 and 18.17% w/w ± 0.39, respectively, (n = 3). Different weight percentages (15 and 20 wt %) of the PB-2 copolymer have been utilized for in vitro release studies of IgG-Fab from composite nanoformulation. A negligible burst release with continuous near zero-order release has been observed from the composite nanoformulation analyzed up to 80 days. In vitro cell viability and biocompatibility studies performed on ocular (human corneal epithelial and retinal pigment epithelium) and mouse macrophage (RAW 264.7) cell lines showed that the synthesized PB copolymer based composite nanoformulations were safe for clinical applications. On the basis of the results observed, it is concluded that PB copolymer based composite nanoformulations can serve as a platform for ocular delivery of therapeutic proteins. In addition, the composite nanoformulation may provide minimal side effects associated with frequent intravitreal injections.

Topical application of a G-Quartet aptamer targeting nucleolin attenuates choroidal neovascularization in a model of age-related macular degeneration

Choroidal neovascularization (CNV) associated with the 'wet' form of age related macular degeneration (AMD) is one of the most common causes of central vision loss among the elderly. The 'wet' form of AMD is currently treated by intravitreal delivery of anti-VEGF agents. However, intravitreal injections are associated with complications and long-term inhibition of VEGF leads to macular atrophy. Thus, there is currently an unmet need for the development of therapies for CNV that target molecules other than VEGF. Here, we describe nucleolin as a novel target for the 'wet' form of AMD. Nucleolin was found on the surface of endothelial cells that migrate from the choroid into the subretinal space in the laser-induced model of 'wet' AMD. AS1411 is a previously described G-quartet oligonucleotide that has been shown to bind nucleolin. We found that AS1411 inhibited the formation of tubes by human umbilical vein endothelial cells (HUVECs) by approximately 27.4% in vitro. AS1411 co-localized with the site of laser induced CNV in vivo. Intravitreally injected AS1411 inhibited laser-induced CNV by 37.6% and attenuated infiltration of macrophages by 40.3%. Finally, topical application of AS1411 led to a 43.4% reduction in CNV. Our observations have potential implications for the development of therapies for CNV and specifically for the 'wet' form of AMD.

Conbercept (KH-902) for the treatment of neovascular age-related macular degeneration

Age-related macular degeneration (AMD) is a progressive, degenerative disease of the retina that occurs with increasing incidence with age and ranks third among the global causes of visual impairment. VEGF has been implicated in the development and progression of neovascular AMD. Drugs that block VEGF, leading to regression of the abnormal blood vessels, are the mainstay of treatment of neovascular AMD, particularly for subfoveal neovascular lesions. Anti-VEGF agents currently in use in neovascular AMD are pegaptanib (Macugen(®)), ranibizumab (Lucentis(®)), bevacizumab (Avastin(®)) and a soluble VEGF receptor decoy aflibercept (Eylea(®)). Recently, China Food and Drug Administration have approved conbercept for the treatment of neovascular AMD in China. Conbercept appears to offer yet another anti-VEGF drug for use in neovascular AMD. However, there is still a need for large, well-designed, randomized clinical trials to ensure its safety and efficacy.

Acute sterile endophthalmitis following intravitreal bevacizumab: case series

Background

Since the ophthalmological community adopted the use of intravitreal bevacizumab as an accepted off-label treatment for neovascular diseases, the amount of knowledge regarding its effects and properties has been increasing continually. In the last few years, there have been an increasing number of reports about sterile intraocular inflammation and intraocular pressure elevations after intravitreal bevacizumab. In the following case series, we describe the clinical presentation and outcomes of ten consecutive cases of patients developing mild-to-severe sterile intraocular inflammation after intravitreal bevacizumab and their management.

Methods

This report presents a retrospective case series. We reviewed the medical records of ten consecutive patients from a group of 46, in whom repackaged bevacizumab in individual aliquots from two vials from the same batch were used. All surgical procedures were performed using standard sterile techniques in the operating room. At each follow-up visit, patients underwent a complete ophthalmological examination including visual acuity assessment, intraocular pressure, biomicroscopy, and posterior fundus examination.

Results

Ten patients presented sterile endophthalmitis with an onset time of 3.5±1.95 days. The clinical characteristics were mild pain, slight visual loss, conjunctival hyperemia, and various degrees of intraocular inflammation with microhypopyon. All cultures were negative. All patients were managed with topical steroids and antibiotics, except two, in whom, due to severe vitreous cells, intravitreal antibiotics were used. Three patients showed a transient elevation of intraocular pressure. Only 50% of the patients regained a visual acuity equal or better to the baseline visual acuity on file.

Conclusion

The increasing number of intravitreal injections of bevacizumab applied every day, due to its widespread acceptance, might be one reason why the number of cases of sterile endophthalmitis is rising. Fast recognition and accurate differential diagnosis is important to avoid unnecessary treatments and long-term complications. The low incidence of this event should not preclude the use of intravitreal injections in eyes that could benefit greatly from this therapy.

One-Year Feasibility Study of Replenish MicroPump for Intravitreal Drug Delivery: A Pilot Study

PURPOSE

To determine the feasibility of the surgical procedure and to collect some safety data regarding the bioelectronics of a novel micro drug pump for intravitreal drug delivery in a Beagle dog model for up to 1 year.

METHODS

Thirteen Beagle dogs were assigned to two groups. The experimental group (n = 11) underwent pars plana implantation of MicroPump; the body of which was sutured episclerally, while its catheter was secured at a pars plana sclerotomy. The control group (n = 2) underwent sham surgeries in the form of a temporary suturing of the MicroPump, including placement of the pars plana tube. Baseline and follow-up exams included ophthalmic examination and imaging. The experimental animals were euthanized and explanted at predetermined time points after surgery (1, 3, and 12 months), while the control animals were euthanized at 3 months. All operated eyes were submitted for histopathology.

RESULTS

Eyes were scored according to a modified McDonald-Shadduck system and ophthalmic imaging. Neither the implanted eyes nor the control eyes showed clinically significant pathological changes beyond the expected surgical changes. The operated eyes showed neither significant inflammatory reaction nor tissue ingrowth through the sclerotomy site compared with the fellow eyes.

CONCLUSION

This study shows that the Replenish Posterior MicroPump could be successfully implanted with good safety profile in this animal model.

TRANSLATIONAL RELEVANCE

The results of this study in a Beagle dog model are supportive of the biocompatibility of Replenish MicroPump and pave the way to the use of these devices for ocular automated drug delivery after further testing in larger animal models.

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.

Current knowledge and trends in age-related macular degeneration: today's and future treatments

PURPOSE

To address the most dynamic and current issues concerning today's treatment options and promising research efforts regarding treatment for age-related macular degeneration. This review is aimed to serve as a practical reference for more in-depth reviews on the subject.

METHODS

An online review of the database PubMed and Ovid were performed, searching for the key words age-related macular degeneration, AMD, VEGF, treatment, PDT, steroids, bevacizumab, ranibizumab, VEGF-trap, radiation, combined therapy, as well as their compound phrases. The search was limited to articles published since 1985. All returned articles were carefully screened, and their references were manually reviewed for additional relevant data. The web page www.clinicaltrials.gov was also accessed in search of relevant research trials.

RESULTS

A total of 363 articles were reviewed, including 64 additional articles extracted from the references. At the end, only 160 references were included in this review.

CONCLUSION

Treatment for age-related macular degeneration is a very dynamic research field. While current treatments are mainly aimed at blocking vascular endothelial growth factor, future treatments seek to prevent vision loss because of scarring. Promising efforts have been made to address the dry form of the disease, which has lacked effective treatment.

Ranibizumab in diabetic macular edema

By 2050 the prevalence of diabetes will more than triple globally, dramatically increasing the societal and financial burden of this disease worldwide. As a consequence of this growth, it is anticipated that there will be a concurrent rise in the numbers of patients with diabetic macular edema (DME), already among the most common causes of severe vision loss worldwide. Recent available therapies for DME target the secreted cytokine, vascular endothelial growth factor (VEGF). This review focuses on the treatment of DME using the first humanized monoclonal antibody targeting VEGF that has been Food and Drug Administration-approved for the use in the eye, ranibizumab (Lucentis(®)).

Topical application of PPADS inhibits complement activation and choroidal neovascularization in a model of age-related macular degeneration

Age-related macular degeneration (AMD) is the most common cause of blindness among the elderly. AMD patients have elevated levels of membrane attack complex (MAC) in their choroidal blood vessels and retinal pigment epithelium (RPE). MAC forms pores in cell membranes. Low levels of MAC result in an elevation of cytokine release such as vascular endothelial growth factor (VEGF) that promotes the formation of choroidal neovascularization (CNV). High levels of MAC result in cell lysis and RPE degeneration is a hallmark of advanced AMD. The current standard of care for CNV associated with wet AMD is intravitreal injection of anti-VEGF molecules every 4 to 12 weeks. Such injections have significant side effects. Recently, it has been found that membrane pore-forming proteins such as α-haemolysin can mediate their toxic effects through auto- and paracrine signaling and that complement-induced lysis is amplified through ATP release followed by P2X receptor activation. We hypothesized that attenuation of P2X receptor activation may lead to a reduction in MAC deposition and consequent formation of CNV. Hence, in this study we investigated topical application of the purinergic P2X antagonist Pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS) as a potential treatment for AMD. We found that 4.17 µM PPADS inhibited formation of HUVEC master junctions and master segments by 74.7%. In a human complement mediated cell lysis assay, 104 µM PPADS enabled almost complete protection of Hepa1c1c7 cells from 1% normal human serum mediated cell lysis. Daily topical application of 4.17 mM PPADS for 3 days attenuated the progression of laser induced CNV in mice by 41.8% and attenuated the deposition of MAC at the site of the laser injury by 19.7%. Our data have implications for the future treatment of AMD and potentially other ocular disorders involving CNV such as angioid streaks, choroidal rupture and high myopia.

Ranibizumab: the first vascular endothelial growth factor inhibitor approved for the treatment of diabetic macular edema

OBJECTIVE

To review the pharmacology, efficacy, and safety data available for ranibizumab and compare the drug to other therapeutic options for diabetic macular edema (DME) to determine its likely role in therapy.

DATA SOURCES

A PubMed search was initially used to identify all trials pertaining to the use of ranibizumab for DME. This search was conducted in February 2013 without a time frame for exclusion of older trials (all references included were published between January 1987 and February 2013). Following a review of the references of these articles, additional sources were obtained from PubMed, the manufacturer's website, and clinicaltrials.gov.

STUDY SELECTION AND DATA EXTRACTION

Trials conducted in animals and those written in a language other than English were excluded. Abstracts of remaining trials were reviewed for determination of relevance to this review. Preference was given to randomized controlled trials. Additional information sources were obtained from a review of references as deemed necessary by the authors.

DATA SYNTHESIS

Six Phase 2 or 3 randomized controlled trials studying the effects of ranibizumab in patients with DME were identified. Within these trials, ranibizumab consistently produced significantly greater gains in mean best corrected visual acuity than focal/grid laser photocoagulation or sham (7.4-12.5 letter improvement with ranibizumab vs 0.5-3 letters following focal/grid laser photocoagulation monotherapy) with a favorable safety and tolerability profile. Ranibizumab was also studied in combination with focal/grid laser photocoagulation, showing no additional gains in vision versus ranibizumab monotherapy.

CONCLUSIONS

The identified trials provide support for the safety and efficacy of ranibizumab in the treatment of vision loss due to DME and present a strong case for the shift to first-line treatment with vascular endothelial growth factor inhibitors from focal/grid laser photocoagulation, the standard of care since the Early Treatment Diabetic Retinopathy Study of 1985.

Digital reader vs print media: the role of digital technology in reading accuracy in age-related macular degeneration

PURPOSE

To compare patient satisfaction, reading accuracy, and reading speed between digital e-readers (Sony eReader, Apple iPad) and standard paper/print media for patients with stable wet age-related macular degeneration (AMD).

METHODS

Patients recruited for the study were patients with stable wet AMD, in one or both eyes, who would benefit from a low-vision aid. The selected text sizes by patients reflected the spectrum of low vision in regard to their macular disease. Stability of macular degeneration was assessed on a clinical examination with stable visual acuity. Patients recruited for the study were assessed for reading speeds on both digital readers and standard paper text. Standardized and validated texts for reading speeds were used. Font sizes in the study reflected a spectrum from newsprint to large print books. Patients started with the smallest print size they could read on the standardized paper text. They then used digital readers to read the same size standardized text. Reading speed was calculated as words per minute by the formula (correctly read words/reading time (s) ·60). The visual analog scale was completed by patients after reading each passage. These included their assessment on 'ease of use' and 'clarity of print' for each device and the print paper.

RESULTS

A total of 27 patients were used in the study. Patients consistently read faster (P<0.0003) on the Apple iPad with larger text sizes (size 24 or greater) when compared with paper, and also on the paper compared with the Sony eReader (P<0.03) in all text group sizes. Patients chose the iPad to have the best clarity and the print paper as the easiest to use.

CONCLUSIONS

This study has demonstrated that digital devices may have a use in visual rehabilitation for low-vision patients. Devices that have larger display screens and offer high contrast ratios will benefit AMD patients who require larger texts to read.

IgG Fab fragments forming bivalent complexes by a conformational mechanism that is reversible by osmolytes

Generated by proteolytic cleavage of immunoglobulin, Fab fragments possess great promise as blocking reagents, able to bind receptors or other targets without inducing cross-linking. However, aggregation of Fab preparations is a common occurrence, which generates intrinsic stimulatory capacity and thwarts signal blockade strategies. Using a panel of biochemical approaches, including size exclusion chromatography, SDS-PAGE, mass spectrometry, and cell stimulation followed by flow cytometry, we have measured the oligomerization and acquisition of stimulatory capacity that occurs in four monoclonal IgG Fabs specific for TCR/CD3. Unexpectedly, we observed that all Fabs spontaneously formed complexes that were precisely bivalent, and these bivalent complexes possessed most of the stimulatory activity of each Fab preparation. Fabs composing bivalent complexes were more susceptible to proteolysis than monovalent Fabs, indicating a difference in conformation between the Fabs involved in these two different states of valency. Because osmolytes represent a class of compounds that stabilize protein folding and conformation, we sought to determine the extent to which the amino acid osmolyte l-proline might impact bivalent Fab complexation. We found that l-proline (i) inhibited the adoption of the conformation associated with bivalent complexation, (ii) preserved Fab monovalency, (iii) reversed the conformation of preformed bivalent Fabs to that of monovalent Fabs, and (iv) separated a significant percentage of preformed bivalent complexes into monovalent species. Thus, Fab fragments can adopt a conformation that is compatible with folding or packing of a bivalent complex in a process that can be inhibited by osmolytes.