A safety evaluation of ranibizumab in the treatment of age-related macular degeneration

Introduction: The use of intravitreal ranibizumab has transformed the outcomes for thousands of patients with wet age related macular degeneration (AMD), which is the leading cause of blindness in developed countries. Prior to its introduction, most patients with wet AMD would rapidly lose central vision. The use of intravitreal ranibizumab has been shown to reduce certifiable visual loss by about a half. Current treatment regimens with ranibizumab in wet AMD require multiple injections over several years and so it is highly relevant to review the safety record of this important drug.

Areas covered: This review considers the important ocular and systemic adverse events (AE) that have been reported in the literature, particularly in the context of the pivotal clinical trials that have been performed. It also reviews the safety of other anti-VEGF drugs that are used in wet AMD, namely bevacizumab and aflibercept, and compares these drugs with ranibizumab.

Expert opinion: Overall, intravitreal ranibizumab can be considered a safe and highly effective drug for patients with wet AMD. However recent concerns about retinal thinning following ranibizumab therapy, possible systemic AE associated with all anti-VEGF drugs and the occurrence of complications relating to drug preparation and delivery must be considered.     

VEGF Trap-Eye for the treatment of neovascular age-related macular degeneration

Background: Age-related macular degeneration (AMD) affects > 14 million individuals worldwide. Although 90% of patients with AMD have the dry form, neovascular AMD accounts for the vast majority of patients who develop legal blindness. Until recently, few treatment options existed for treatment of neovascular AMD. The advent of anti-VEGF therapy has significantly improved the safe and effective treatment of neovascular AMD. In addition to two anti-VEGF drugs currently in widespread use, ranibizumab and bevacizumab, a number of medications that interrupt angiogenesis are currently under investigation. One promising new drug is aflibercept (VEGF Trap-Eye), a fusion protein that blocks all isoforms of VEGF-A and placental growth factors-1 and -2. Objective: To review the current literature and clinical trial data regarding VEGF Trap-Eye for the treatment of neovascular AMD. Methods: Literature review. Results/conclusion: VEGF Trap-Eye is a novel anti-VEGF therapy, with Phase I and II trial data indicating safety, tolerability and efficacy for the treatment of neovascular AMD. Two Phase III clinical trials (VIEW-1 and VIEW-2) comparing VEGF Trap-Eye to ranibizumab are currently continuing and will provide vital insight into the clinical applicability of this drug.     

VEGF inhibitors for the treatment of neovascular age-related macular degeneration

Age-related macular degeneration (AMD) is the leading cause of blindness in the Western world for those patients aged 50 years or older. Neovascular AMD, a subtype characterized by the growth of new, pathologic blood vessels, results in most of the cases of severe and rapid vision loss associated with AMD. A critical activator of angiogenesis in neovascular AMD is VEGF. Several therapies have been and are now being developed for neovascular AMD, with the goal of inhibiting VEGF. These VEGF inhibitors include the RNA aptamer pegaptanib, partial and full-length antibodies ranibizumab and bevacizumab, VEGF receptor decoy VEGF Trap, small interfering RNA-based therapies bevasiranib and AGN211745, sirolimus, and tyrosine kinase inhibitors including vatalanib, pazopanib, TG100801, TG101095, AG013958 and AL39324. At present, established therapies have met with great success in reducing the vision loss associated with neovascular AMD, whereas those still investigational in nature offer the potential for further advances.     

An update on the pharmacotherapy of neovascular age-related macular degeneration

Introduction: Neovascular age-related macular degeneration (AMD) is currently the most common cause of legal blindness in industrialized countries. The advent of pharmacotherapy with intravitreal VEGF inhibitors has greatly improved outcomes for the treatment of this disease.

Areas covered: The present review is divided into two major sections: the period prior to the use of anti-VEGF agents (triamcinolone acetonide, verteporfin photodynamic therapy) and the period following their introduction (pegaptanib sodium, bevacizumab, ranibizumab, aflibercept). The main pharmacological and clinical characteristics of each therapy are summarized.

Expert opinion: Monotherapy with anti-VEGF agents is currently the ‘gold standard' for treating neovascular AMD, but, with several drug choices and various different dosing regimens available, there is still wide variability in how individual clinicians manage their patients. Despite improved visual outcomes, there remains a significant unmet need for better treatments as the frequent office visits and injections associated with anti-VEGF therapy are costly and place a significant burden on patients, their family members and physicians.     

Emerging treatments for wet age-related macular degeneration

Introduction: Wet or exudative age-related macular degeneration (AMD) is the leading cause of blindness in the United States for individuals over the age of 65 years. Wet AMD is characterized by the formation of choroidal neovascularization, which can lead to edema, hemorrhage and scarring of the macula. This leads to metamorphopsia and vision loss. Without treatment, the loss of vision is permanent. The current gold standard treatment of wet AMD consists of intravitreal injections of anti-vascular endothelial growth factor (VEGF) medications.

Areas covered: Numerous new therapies in the drug pipeline aim at addressing limitations of current treatments. Future therapies involve novel compounds that attack different parts of the VEGF cascade, novel delivery systems aimed at reducing the frequency of intraocular injections, combination therapies and the use of radiation in conjunction with intravitreal therapies.

Expert opinion: Limitations of current treatments include the need for repeated injections, the high financial costs and treatment burdens of repeated injections, the risk of adverse ocular and systemic adverse events, and the inability to completely reverse the disease process of wet AMD. There are many new therapies and approaches in the pipeline which hold promise for improving the treatment of wet AMD.     

Anti-VEGF agents for age-related macular degeneration

Age-related macular degeneration (AMD) is a leading cause of legal blindness in the elderly in the industrialized world and the third major cause of blindness around the globe. Although neovascular AMD is less prevalent than atrophic AMD, it accounts for most cases with severe visual loss from AMD. VEGF seems to be a key contributary factor in the pathophysiology underlying neovascular AMD. Until recently, treatment options for neovascular AMD were limited. With the recent development of anti-VEGF therapies that have demonstrated efficacy in studies with broad eligibility criteria, the repertoire of treatments for neovascular AMD has been significantly expanded to now include the various recognized angiographic lesion subtypes. To discuss recent anti-VEGF agents in the management of AMD. Although therapy with anti-VEGF agents is the gold standard with promising results, many intravitreal injections are often required, and they do not cure all cases of wet AMD. With the recent advances in the medical therapy of exudative AMD, there is reason to be optimistic about future management of AMD as well.     

Systemic thromboembolic adverse events in patients treated with intravitreal anti-VEGF drugs for neovascular age-related macular degeneration: an update

Introduction: Intravitreal anti-VEGF is the most effective therapy for wet AMD, although systemic effects on the endothelium cannot be excluded.

Areas covered: The purpose of this review was to evaluate risk of thromboembolic events associated with intravitreal anti-VEGF.

Expert opinion: Current data are insufficient to confirm the safety of these compounds, due to the paucity of specific studies. Thus, pharmacovigilance for all anti-VEGF should be improved to verify the true role of anti-VEGF in the occurrence of systemic adverse events.     

Systemic thromboembolic adverse events in patients treated with intravitreal anti-VEGF drugs for neovascular age-related macular degeneration: an overview

Introduction: Anti-VEGF therapy improved the quality of life for millions of patients suffering from wet age-related macular degeneration (wet-AMD); unfortunately, this therapy involves multiple injections over many years. The administration of anti-VEGF can overcome the blood-retinal barrier with agents entering the systemic circulation and causing a significant decrease in VEGF serum concentration. Although circulating VEGF protects the integrity and patency of vessels, prolonged anti-VEGF treatment has the potential to increase the risk of thromboembolic events.

Areas covered: In this review, we discuss the safety data from recent trials involving available anti-VEGF drugs.

Expert opinion: During the 2 years of follow-up in the relevant clinical trials, the rates of serious adverse events such as stroke, heart attack and death were similar for patients treated with different anti-VEGF drugs. Moreover the arterial thrombotic risk appears sufficiently low when compared with the natural incidence of arterial thrombotic events in this category of elderly patients and acceptably balanced against the advantage of improved vision. Since the use of these drugs is likely to become increasingly widespread and prolonged, it is desirable that the scientific community improves the pharmacovigilance program on all anti-VEGF drugs, expanding knowledge with studies that compares head to head all four compounds belonging to anti-VEGF armamentarium.     

Safety of monoclonal antibodies and related therapeutic proteins for the treatment of neovascular macular degeneration: addressing outstanding issues

Introduction: The vascular endothelial growth factor (VEGF) inhibitors most widely used to treat neovascular age-dependent macular degeneration (nAMD) are different proteins with structural features potentially relevant to adverse effects (AEs). Two of these are also established in cancer therapy (with higher dosages and AEs). The importance of ocular AE and extraocular activities is still a subject of controversy and ongoing research.

Areas covered: Potential risks of intraocular VEGF inhibition based on prospective studies, in vitro investigations, pharmacokinetics, and hints from anti-cancer treatment.

Expert opinion: nAMD is a frequently observed chronic clinical condition severely affecting the visual function of elderly persons. Intravitreal injection of VEGF-inactivating proteins is highly effective to prevent loss of vision. Anti-VEGF therapy is well tolerated, and low rates of ocular and systemic AEs in smaller trials suggest a very high benefit/risk ratio. The proteins established in nAMD therapy show similar efficacies. In the controversy over the off-label use of bevacizumab purely on grounds of much lower cost, the small, but potentially relevant differences between the available drugs are easily either dramatized (by pharmaceutical companies) or trivialized (by health insurances) and even political interference is involved. Facing the lack of a convincing body of evidence regarding safety, further long-term study results seem necessary.     

Pegaptanib sodium for the treatment of neovascular age-related macular degeneration

This article reviews pegaptanib sodium, a compound developed by Eyetech Pharmaceuticals Inc. and Pfizer Inc., for the treatment of neovascular age-related macular degeneration (AMD). Traditional treatment approaches to neovascular AMD have included destructive therapies such as thermal laser photocoagulation and photodynamic therapy; the use of pegaptanib sodium heralds a new treatment approach that is a non-destructive therapy based on the inhibition of vascular endothelial growth factor activity in the eye. This diminishes the neovascular drive in the pathologically hyperpermeable state of the diseased eye. Pegaptanib sodium is one of the first therapeutics belonging to the class of compounds known as aptamers. The chemistry, mechanism of action, pharmacokinetics and rationale for the clinical use of the drug are reviewed. The article highlights and summarises the results of the multi-centre, randomised, sham-controlled clinical trials with pegaptanib sodium to treat subfoveal choroidal neovascularisation in AMD. In addition, the safety profile is reviewed.     

Clinical safety of ranibizumab in age-related macular degeneration

Importance of the field: Clinical safety of pharmaceutical products in the elderly is vital because of their increased risk of cardiac and other adverse events.

Areas covered in this review: Search of the Medline database, including articles and abstracts from 1984 to 2009.

What the reader will gain: Knowledge of ocular and systemic risks: The rate of endophthalmitis was 0.05% per injection (MARINA) and <0.1% per injection (ANCHOR), rates confirmed in a retrospective analysis of 14,320 injections. Moderate increases in intraocular pressure were transient, and incidences of intraocular inflammation were rarely serious. Systemic arterial thromboembolic events occurred in 4.6 and 0% of ranibizumab-treated patients and in 3.8 and 0% of sham-treated patients in MARINA (2 years) and PIER (1 year), respectively. In SAILOR, there was a numerically higher rate of cerebrovascular stroke with 0.5 mg ranibizumab compared with 0.3 mg ranibizumab (1.2 vs 0.7%), which was a non-statistically significant trend in patients with a history of stroke.

Take home message: Although further studies to investigate the risk of stroke with ranibizumab therapy are required, repeated intravitreal ranibizumab was well tolerated and not associated with clinically significant safety risks during up to 2 years of treatment.     

A review of drug options in age-related macular degeneration therapy and potential new agents

Age-related macular degeneration (AMD) is the leading cause of legal blindness in people > 50 years of age in the developed world. AMD is both a debilitating and costly disease for the individual and the community. Greater understanding of the mechanisms and pathways involved in causing the visual loss in AMD has resulted in the advent of several newer and more effective treatment options, making it an exciting time in the management of AMD. This paper will examine the principles behind the existing drug therapies available, as well as those being developed in the management or prophylaxis of AMD and its vision-threatening complications.     

VEGF-targeted therapy and beyond: pharmacotherapy and emerging treatments in agerelated macular degeneration

Treatment of age-related macular degeneration (AMD) has changed dramatically over the last decade. It has evolved from primarily destructive therapies (laser-based treatment strategies) to nondestructive therapies (intravitreal pharmacotherapies that target angiogenesis). Intermittent intravitreal ranibizumab, an inhibitor of VEGF, is currently the gold standard of care for neovascular AMD as it is the only treatment where a significant proportion of treated eyes have been shown to experience improvements in visual acuity. As our understanding of the pathological and molecular mechanisms involved in AMD increases, multiple new treatments are emerging. Distinct therapeutic approaches are being used, including inhibition of oxidative stress, interference with the visual cycle and immunomodulation. Targets within the complex cycle of angiogenesis include upstream pathways, such as mTOR and HIF-α, and downstream targets include integrins, PDGF and receptor tyrosine kinases.     

Ranibizumab: the evidence of its therapeutic value in neovascular age-related macular degeneration

Introduction:

Neovascular age-related macular degeneration (AMD) is the leading cause of severe, irreversible visual impairment in people over 60 years of age. Neovascular AMD is characterized by abnormal growth of blood vessels under the retina, specifically the macula. These vessels leak blood and fluids, damaging the retina and its photoreceptors, resulting in permanent loss of central vision. Vascular endothelial growth factor-A (VEGF-A) has been shown to play a critical role in the pathogenesis of neovascular AMD. In the US, ranibizumab, a VEGF-A blocker, is approved and indicated for the treatment of patients with neovascular AMD.

Aims:

To review the clinical evidence for ranibizumab in the treatment of neovascular AMD.

Evidence review:

Phase III clinical trial data have established ranibizumab as a safe and well-tolerated treatment for neovascular AMD. Monthly intravitreal injections of ranibizumab result in a statistically significantly greater proportion of patients losing <15 letters of visual acuity (VA) and statistically significant increases in the mean number of letters gained compared with controls. Anatomically, ranibizumab results in stabilization in the mean area of choroidal neovascularization (CNV) and statistically significant reductions in the mean area of leakage compared with controls. Although there is limited economic evidence available, ranibizumab therapy for neovascular AMD appears to deliver a significant degree of value gain in terms of quality of life when compared with other neovascular AMD interventions.

Place in therapy:

Clinical evidence establishes ranibizumab as a first-line therapy option for virtually all treatable neovascular AMD patients. Updating neovascular AMD treatment guidelines to reflect the evidence base for ranibizumab as a preferred first-line therapy would be beneficial for physicians in making informed treatment choices and ultimately helping to ensure the best care for patients.     

Pharmacotherapy of age-related macular degeneration

Background: Age-related macular degeneration is the leading cause of blindness in the developed world. The number of persons with vision loss from age-related macular degeneration is projected to increase dramatically over the next few decades. Therefore, effective therapeutic and prophylactic agents are greatly needed. Objective: This article will discuss some of the newer treatment strategies that may help to reduce the incidence of visual loss from age-related macular degeneration. Some of these therapies and strategies can be implemented today, while many are hypothetical based on current laboratory data and ongoing clinical trials. Methods: A review of the literature and ongoing clinical trials was undertaken. Conclusion: Current therapies using antioxidants for prevention of the progression of age-related macular degeneration and anti-vascular endothelial growth factor therapies for neovascular age-related macular degeneration have given us tools for tackling this disease better and reducing the number of patients with vision loss. Combinations of some of the existing treatments and new forms of therapy may yet further decrease the treatment burden in the future.     

Drugs in Phase II clinical trials for the treatment of age-related macular degeneration

Introduction: The clinical development of anti-VEGF therapies for the treatment of exudative age-related macular degeneration (wet AMD) has revolutionized ophthalmology. Indeed, it has provided clinicians and patients with treatments that lessen visual loss from in a disease that once was uniformly blinding. Although blindness is yet to be eradicated from AMD, repeated intraocular anti-VEGF injections are required to preserve a patient’s vision. Therefore, further advances in this field are necessary.

Areas covered: This review provides an overview of the agents that are in mid-stage phase trials for both exudative (wet AMD) and nonexudative macular degeneration (dry AMD). For wet AMD, new agents intend to enhance efficacy, develop alternative delivery such as eye drops, investigate alternate targets and construct sustained release strategies. For advanced dry AMD, the goal is to develop a strategy to slow or stop progressive loss of retinal tissue seen in geographic atrophy, the hallmark of advanced dry AMD.

Expert opinion: It is important to develop better more sensitive biomarkers, validating different approvable clinical trial endpoints and stratifying patients on their genetic polymorphisms. These developments should help to progress the already rapidly developing field of macular degeneration therapy.     

Drug delivery techniques for treating age-related macular degeneration

Introduction: Currently, the standard therapy for neovascular age-related macular degeneration involves the use of anti-vascular endothelial growth factor (VEGF) drugs, which are delivered by repeated office-based intravitreal injections. This treatment is generally very effective in stabilizing or improving vision, although repeated injections create a burden for patients, family members and physicians. In addition, the cumulative risks of endophthalmitis and other complications increase with the number of injections.

Areas covered: In the clinic, much attention is focused on the relative efficacies of the three major anti-VEGF medications (bevacizumab, ranibizumab and aflibercept) as well as the most popular re-injection regimens (monthly, as-needed and treat-and-extend). In theory, intravitreal anti-VEGF drug delivery with sustained-release devices would offer similar visual results with fewer required re-injections. Various approaches have been studied, including noninvasive techniques, intraocular implants and colloidal carriers, such as liposomes, microparticles and nanoparticles.

Expert opinion: Despite its theoretical appeal, sustained-release drug delivery will not replace current techniques unless it offers one or more advantages in efficacy, safety, convenience or cost. Currently, many patients maintain stable vision with intravitreal injections at intervals of 2 months or longer, so sustained-release techniques will have to lengthen these intervals substantially to become widely accepted. As we continue to collect data from clinical trials, the role of sustained-release techniques will become better defined.     

Emerging drugs for age-related macular degeneration

Age-related macular degeneration (AMD) is a leading cause of blindness that until recently had no recognised drug treatment. In wet AMD, choroidal neovascularisation (CNV) causes a profound loss of central vision. CNV is a complex process in which tissue ischaemia and/or inflammation is thought to trigger production of angiogenic signal molecules. The release of VEGF appears to be particularly important. Verteporfin photodynamic therapy was the first drug therapy to be licensed for the treatment of some types of wet AMD. Other treatments directly targeting VEGF or other aspects of angiogenesis, such as pegaptanib, ranibizumab and anecortave acetate, have either recently been licensed or are in the advanced stages of development. These and other promising treatment options such as combination strategies are reviewed.     

Current and future therapies for age-related macular degeneration

Background: Age-related macular degeneration is the leading cause of blindness, with an increasing incidence as the elderly population expands. Objective: In this article we review current therapeutic strategies and discuss possible future targets. Methods: A review of the literature and ongoing clinical trials was undertaken. Results: Currently, established therapies for neovascular AMD-like photodynamic therapy and anti-VEGF therapies allow stabilization or even improvement of vision. Potential future drugs under development for advanced AMD or its prevention target the signal transduction cascade of different angiogenic molecules. These drugs intervene at different levels of the involved processes including the RNA production and specific protein expression as well as inflammatory, apoptotic, or metabolic processes. Conclusion: Combining different strategies targeting angiogenesis, inflammation and apoptosis, or interfering early in – or even prior to – the formation of choroidal neovascularization, may improve the future management of age-related macular degeneration.