Antiangiogenic therapy in neovascular age-related macular degeneration

First reported case of Doyne honeycomb retinal dystrophy (Malattia Leventinese/autosomal dominant drusen) in Scandinavia

BACKGROUND

Doyne honeycomb retinal dystrophy (DHRD)/malattia leventinese (ML) is an autosomal dominant, progressive retinal disorder characterized by massive central retinal drusen often partly coalescent forming a characteristic honeycomb-like pattern. Debut of vision loss often occurs in early to mid-adulthood, and the degree varies. A single variant in EFEMP1: c.1033C>T (R345W) has been identified as the cause in all cases.

METHODS

Following DNA isolation, exome sequencing was performed in seven genes associated with flecked retina. Direct sequencing was used for variant verification.

RESULTS

We report the first Scandinavian case of molecular genetically verified DHRD/ML: a 57-year-old woman debuting with vision loss and metamorphopsia. On both eyes, ophthalmological findings included massive hard drusen in the macular region and nasal to the optic disc as well as macular hyperpigmentation. Secondary choroidal neovascularizations were identified on both eyes, and anti-vascular endothelial growth factor was administered, without effect.

CONCLUSION

Molecular genetic investigation revealed heterozygosity for the known pathogenic missense variant in EFEMP1: c.1033C>T (R345W) previously reported in relation to DHRD/ML. Family history revealed no other cases of similar visual impairment suggesting a de novo mutation. Furthermore, there was no correlation between the unique DHRD/ML haplotypes reported in the literature and our patient.

Prefilled syringes for intravitreal drug delivery

Intravitreal injections of anti-vascular endothelial growth factor (VEGF) medications play an increasingly critical role in numerous retinal vascular diseases. Initially, anti-VEGF medications came in vials that had to be drawn up by the physician into a syringe for administration. In 2018, the US Food and Drug Administration (US FDA) approved the ranibizumab 0.3 mg prefilled syringe (PFS), and in October 2016, the US FDA approved the ranibizumab 0.5 mg PFS. This article discusses the advantages of the PFS, including reduced injection time, possible reduced risk of endophthalmitis, reduction in intraocular air bubbles and silicone oil droplets, and improved precision in the volume and dose of intravitreal ranibizumab administered, along with possible disadvantages. Implications of the innovation of the PFS on intravitreal injection technique and clinical practice pattern are discussed and reviewed.

The impact of subconjuctivally injected EGF and VEGF inhibitors on experimental corneal neovascularization in rat model

AIM AND SCOPE

To investigate the inhibitory effect of subconjunctival application of VEGF antibodies bevacizumab, ranibizumab, pegaptanib, and HER2 antibody trastuzumab on corneal neovascularization in a rat model of experimental corneal neovascularization.

MATERIAL AND METHOD

Thirty male Wistar albino rats were included in the study. A chemical burn was induced in central cornea of one eye of the rats by a 75% silver nitrate and 25% potassium nitrate stick. Rats were randomly divided into five groups so that each group contained 6 subjects. Right after the chemical burn, 0.1 ml serum physiologic was injected subconjuctivally in control group (group 1). 1.25 mg/0.05 ml bevacizumab was injected in group 2; 1.2 mg/0.1 ml trastuzumab was injected in group 3; 0.5 mg/0.05 ml ranibizumab was injected in group-4; and 0.3 mg/0.1 ml pegaptanib was injected in group 5. On the 8th day of the experiment, rat corneas were photographed by digital photo-camera. Later, eyes of the sacrificed rats were enucleated and corneal speciements were histopathologically analyzed. The percentages of neovascularization on corneal photographs were examined with digital image analysis.

RESULTS

The percentage of corneal neovascularization in all treatment groups was found to be significantly lower than the control group (p < 0.05). Bevacizumab was found to be more effective than all other agents (p < 0.05). While the degree of inflammation and vascularization in bevacizumab and trastuzumab groups were significantly lower than the control group (p < 0.05), the difference was not significant in ranibizumab and pegaptanib groups (p > 0.05). In all treatment groups, fibroblast intensity was significantly lower than the control group. In terms of corneal thickness, no significant difference was observed between treatment and control groups (p > 0.05).

CONCLUSION

Bevacizumab, ranibizumab, pegaptanib, and trastuzumab were found effective for the inhibition of corneal NV. In our study we detected that the most effective agent was bevacizumab.

CCR3 and choroidal neovascularization

Age-related macular degeneration (AMD) is the leading cause of irreversible blindness in the elderly in industrialized countries. The "wet" AMD, characterized by the development of choroidal neovacularization (CNV), could result in rapid and severe loss of central vision. The critical role of vascular endothelial growth factor A (VEGF-A) in CNV development has been established and VEGF-A neutralization has become the standard care for wet AMD. Recently, CCR3 was reported to play an important role in CNV development and that CCR3 targeting was reported to be superior to VEGF-A targeting in CNV suppression. We investigated the role of CCR3 in CNV development using the Matrigel induced CNV and found that in both rats and mice, CNV was well-developed in the control eyes as well as in eyes treated with CCR3 antagonist SB328437 or CCR3 neutralizing antibodies. No statistically significant difference in CNV areas was found between the control and SB328437 or CCR3-ab treated eyes. Immunostaining showed no specific expression of CCR3 in or near CNV. In contrast, both VEGF-A neutralizing antibodies and rapamycin significantly suppressed CNV. These results indicate that CCR3 plays no significant role in CNV development and question the therapeutic approach of CCR3 targeting to suppress CNV. On the other hand, our data support the therapeutic strategies of VEGF-A and mTOR (mammalian target of rapamycin) targeting for CNV.

Incidence of hemorrhagic complications after intravitreal bevacizumab (avastin) or ranibizumab (lucentis) injections on systemically anticoagulated patients

PURPOSE

To assess the risk of hemorrhagic complications when performing intravitreal injections on systemically anticoagulated patients.

METHODS

A single-center retrospective case series of 520 consecutive patients (675 eyes) receiving 3,106 antivascular endothelial growth factor injections. Patients on the systemic anticoagulants Coumadin (warfarin sodium) or Plavix (clopidogrel bisulfate) were identified, as well as patients on aspirin. Demographic parameters were recorded, as well as relevant anticoagulant medications, preoperative/postoperative best-corrected visual acuities and intraocular pressures, previous ocular surgery, relative ocular diagnoses, and injection complications.

RESULTS

Of all patients, 104 were on Coumadin (134 eyes; 548 injections), 90 were on Plavix (123 eyes; 523 injections), 7 were on both Coumadin and Plavix (8 eyes; 33 injections), and 319 were not anticoagulated (400 eyes; 2002 injections). Also, 1,254 injections were on patients taking aspirin. There were no hemorrhagic complications (choroidal hemorrhage, vitreous hemorrhage, or increased submacular hemorrhage) noted in the Plavix (P = 1.0000; 95% confidence interval = 0.0000-0.0088), Coumadin (P = 1.0000; 95% confidence interval = 0.0000-0.0084), or aspirin (P = 1.0000; 95% confidence interval = 0.0000-0.0037) groups.

CONCLUSION

The risk of hemorrhagic complications in systemically anticoagulated patients receiving intravitreal injections is extremely low. Because of the demonstrated thromboembolic risk of stopping anticoagulant therapy, we recommend that patients continue their current regiment without cessation.

A subretinal matrigel rat choroidal neovascularization (CNV) model and inhibition of CNV and associated inflammation and fibrosis by VEGF trap

PURPOSE

The exudative, or the wet form of age-related macular degeneration (AMD) is characterized by choroidal neovascularization (CNV). A subretinal Matrigel (BD Biosciences, Bedford MA) model of CNV is described here, along with the effects of vascular endothelial growth factor (VEGF) neutralization on the development of CNV and associated inflammation and fibrosis.

METHODS

CNV was induced in adult Sprague-Dawley rats by subretinal injection of Matrigel. CNV growth and associated leukocyte infiltration and collagen deposition were examined. VEGF Trap (Regeneron Pharmaceuticals, Tarrytown, NY), a recombinant protein that comprises portions of the extracellular domains of VEGF receptors 1 and 2 and that binds all isoforms of VEGF-A as well as placental growth factor with high affinity, was administered subcutaneously.

RESULTS

Initiation of CNV was detected 4 days after Matrigel injection and then increased progressively in size. Systemic administration of VEGF Trap beginning on day 2 and 6 completely prevented development of CNV. When CNV was allowed to develop for 10 days before treatment was initiated, VEGF Trap not only prevented its further progression, but also induced substantial regression of existing lesions. In addition, VEGF Trap treatment reduced the total lesion volume and largely prevented the progressive leukocyte infiltration and fibrosis associated with CNV.

CONCLUSIONS

The subretinal Matrigel CNV model provides a convenient tool for the study of the diverse components of complex CNV lesions. The data not only confirm the critical roles of VEGF in the development and maintenance of CNV, but further demonstrate that VEGF and other VEGF receptor 1 ligands promote CNV-associated inflammation and fibrosis.

Intravitreal injection of therapeutic agents

BACKGROUND

Intravitreal injection (IVI) with administration of various pharmacological agents is a mainstay of treatment in ophthalmology for endopthalmitis, viral retinitis, age-related macular degeneration, cystoid macular edema, diabetic retinopathy, uveitis, vascular occlusions, and retinal detachment. The indications and therapeutic agents are reviewed in this study.

METHODS

A search of the English, German, and Spanish language MEDLINE database was conducted. A total of 654 references spanning the period through early 2008 were individually evaluated.

RESULTS

The advantage of the IVI technique is the ability to maximize intraocular levels of medications and to avoid the toxicities associated with systemic treatment. Intravitreal injection has been used to deliver several types of pharmacological agents into the vitreous cavity: antiinfective and antiinflammatory medications, immunomodulators, anticancer agents, gas, antivascular endothelial growth factor, and several others. The goal of this review is to provide a detailed description of the properties of numerous therapeutic agents that can be delivered through IVI, potential complications of the technique, and recommendations to avoid side effects.

CONCLUSION

The IVI technique is a valuable tool that can be tailored to the disease process of interest based on the pharmacological agent selected. This review provides the reader with a comprehensive summary of the IVI technique and its multitude of uses.

Constitutive and oxidative-stress-induced expression of VEGF in the RPE are differently regulated by different Mitogen-activated protein kinases

PURPOSE

Vascular endothelial growth factor (VEGF) is a fundamental factor for angiogenesis. It plays important roles in pathological conditions (e.g. the development of wet AMD), but also in the healthy organism) e.g. in maintaining the vasculature and supporting the retina). Recent therapies to treat the wet AMD focus on neutralizing VEGF indiscriminately. VEGF is constitutively expressed in the retina, but its expression is upregulated by various (noxious) stimuli, e.g. oxidative stress or hypoxia. Discrimination between constitutive expression of VEGF and its pathological upregulation might provide the possibility of focusing on inhibiting the pathological expression only. Here, we focused on the influence of different mitogen-activated protein kinase (MAPK) (p38, Erk, JNK) on the secretion and expression of VEGF, with or without being challenged by oxidative stress.

METHODS

VEGF secretion was measured using a perfusion organ culture model; expression was examined in primary RPE culture and Western blotting.

RESULTS

Constitutive VEGF expression and secretion can be diminished by inhibiting p38, while inhibiting Erk or JNK does not show a significant effect. When challenged with oxidative stress (250 microM t-butylhydroperoxide), VEGF expression and secretion increases and the influence of the MAPK changes: While p38 still accounts for about 30% of the secretion, Erk shows a similar influence. Inhibiting JNK presents conflicting results. In organ culture, inhibiting JNK significantly increases VEGF secretion after stimulation with 250 microM tBH, while with regard to VEGF expression in RPE cell culture, this effect could not be seen.

CONCLUSION

Constitutive and oxidative stress induced VEGF secretion, and expression is differently regulated, which might offer an opportunity to selectively inhibit pathological VEGF expression only.

The R345W mutation in EFEMP1 is pathogenic and causes AMD-like deposits in mice

Age-related macular degeneration (AMD) is the most common cause of vision loss in developed countries. A defining characteristic of this disorder is the accumulation of material between Bruch's membrane and the retinal pigment epithelium (RPE), first as microscopic basal deposits and later as clinically evident drusen. The pathogenesis of these deposits remains to be defined. Biochemical and genetic studies have suggested that inflammation and complement activation may play roles in AMD. Several lines of evidence also suggest that alterations to the extracellular matrix (ECM) of the RPE and choroid contribute to the development of AMD. The inherited macular degeneration Doyne honeycomb retinal dystrophy/Malattia Leventinese is thought to be caused by an R345W mutation in the EFEMP1 gene (also called fibulin-3). The pathogenicity of this mutation has been questioned because all individuals identified to date with the R345W mutation have shared a common haplotype. We investigated the pathogenicity of this mutation in families with early-onset macular degeneration and by generating Efemp1-R345W knockin mice. Genetic studies show that one of the identified families with the R345W mutation has a novel haplotype. The mutant Efemp1-R345W mice develop deposits of material between Bruch's membrane and the RPE, which resemble basal deposits in patients with AMD. These basal deposits contain Efemp1 and Timp3, an Efemp1 interacting protein. Evidence of complement activation was detected in the RPE and Bruch's membrane of the mutant mice. These results confirm that the R345W mutation in EFEMP1 is pathogenic. Further, they suggest that alterations in the ECM may stimulate complement activation, demonstrating a potential connection between these two etiologic factors in macular degeneration.