Systemic Bevacizumab (Avastin) Therapy for Neovascular Age-Related Macular Degeneration

Intraocular drugs: pharmacokinetic strategies and the influence on efficacy and durability

INTRODUCTION

The modern treatment of chorioretinal vascular diseases follows the recent development and rapid adoption of drugs that inhibit vascular endothelial growth factor (VEGF). All anti-VEGF drugs are delivered intravitreally, with clinical behavior, including efficacy, durability, and safety, largely determined by their pharmacokinetic properties.

AREAS COVERED

Properties of these new drugs include additional binding targets (placental growth factor (PlGF) and angiopoietin 2 (Ang 2)), binding affinity, potency, intravitreal half-life, and increased molar dose. A PubMed search for 'pharmacokinetics of anti-VEGF drugs' was performed from 2000 to 2023. Relevant studies were reviewed and referred to in the manuscript.

EXPERT OPINION

Early developers concentrated on improving efficacy, but since maximum efficacy with VEGF inhibition has been reached, development has pivoted to extending the duration of action. Durability strategies include inhibiting additional pathways (faricimab), increasing molar dose (abicipar, brolucizumab, faricimab, and aflibercept 8 mg), and prolonging the intravitreal half-life (abicipar and KSI-301). Recent phase 3 trials demonstrated modest improvements in durability, but failures that might be attributed to these strategies (conjugation and manufacturing processes) have occurred. Future drug development focuses on extending duration of action with implantable reservoirs (ranibizumab port delivery system), sustained release devices (tyrosine kinase inhibitors), and gene therapy.

Treatment of neovascular age-related macular degeneration with anti-vascular endothelial growth factor drugs: progress from mechanisms to clinical applications

Neovascular age-related macular degeneration (nARMD) is an important cause of visual impairment and blindness in the elderly, with choroidal neovascularization in the macula as the main pathological feature. The onset of nARMD is closely related to factors including age, oxidative stress, and lipid metabolism. Vascular endothelial growth factor (VEGF) is an important factor contributing to nARMD as well as choroidal neovascularization and retinal leakage formation. At present, anti-VEGF therapy is the only treatment that improves vision and halts disease progression in most patients, making anti-VEGF drugs a landmark development for nARMD treatment. Although intravitreal injection of anti-VEGF drugs has become the first-line treatment for nARMD, this treatment has many shortcomings including repeated injections, poor or no response in some patients, and complications such as retinal fibrosis. As a result, several new anti-VEGF drugs are being developed. This review provides a discussion of these new anti-VEGF drugs for the treatment of nARMD.

Anti-angiogenic biomolecules in neovascular age-related macular degeneration; therapeutics and drug delivery systems

Blindness in the elderly is often caused by age-related macular degeneration (AMD). The advanced type of AMD known as neovascular AMD (nAMD) has been linked to being the predominant cause of visual impairment in these people. Multiple neovascular structures including choroidal neovascular (CNV) membranes, fluid exudation, hemorrhages, and subretinal fibrosis, are diagnostic of nAMD. These pathological alterations ultimately lead to anatomical and visual loss. It is known that vascular endothelial growth factor (VEGF), a type of proangiogenic factor, mediates the pathological process underlying nAMD. Therefore, various therapies have evolved to directly target the disease. In this review article, an attempt has been made to discuss general explanations about this disease, all common treatment methods based on anti-VEGF drugs, and the use of drug delivery systems in the treatment of AMD. Initially, the pathophysiology, angiogenesis, and different types of AMD were described. Then we described current treatments and future treatment prospects for AMD and outlined the advantages and disadvantages of each. In this context, we first examined the types of therapeutic biomolecules and anti-VEGF drugs that are used in the treatment of AMD. These biomolecules include aptamers, monoclonal antibodies, small interfering RNAs, microRNAs, peptides, fusion proteins, nanobodies, and other therapeutic biomolecules. Finally, we described drug delivery systems based on liposomes, nanomicelles, nanoemulsions, nanoparticles, cyclodextrin, dendrimers, and composite vehicles that are used in AMD therapy.

Recent advances of anti-angiogenic inhibitors targeting VEGF/VEGFR axis

Vascular endothelial growth factors (VEGF), Vascular endothelial growth factor receptors (VEGFR) and their downstream signaling pathways are promising targets in anti-angiogenic therapy. They constitute a crucial system to regulate physiological and pathological angiogenesis. In the last 20 years, many anti-angiogenic drugs have been developed based on VEGF/VEGFR system to treat diverse cancers and retinopathies, and new drugs with improved properties continue to emerge at a fast rate. They consist of different molecular structures and characteristics, which enable them to inhibit the interaction of VEGF/VEGFR, to inhibit the activity of VEGFR tyrosine kinase (TK), or to inhibit VEGFR downstream signaling. In this paper, we reviewed the development of marketed anti-angiogenic drugs involved in the VEGF/VEGFR axis, as well as some important drug candidates in clinical trials. We discuss their mode of action, their clinical benefits, and the current challenges that will need to be addressed by the next-generation of anti-angiogenic drugs. We focus on the molecular structures and characteristics of each drug, including those approved only in China.

Patient adherence to therapy after switch to aflibercept from bevacizumab or ranibizumab for treatment-refractory neovascular age-related macular degeneration

PURPOSE

Clinical trials have demonstrated that switching patients from intravitreal bevacizumab (IVB) or ranibizumab (IVR) to aflibercept (IVA) for treatment-refractory neovascular age-related macular degeneration (nAMD) can decrease the injection frequency. This study evaluated whether there was a difference in the rate of injections or nonadherent events after switching therapies.

METHODS

The study comprised a retrospective, cross-sectional analysis of patients treated for nAMD from 2010 to 2018 who received ≥3 intravitreal injections of IVB/IVR prior to switching to IVA because of treatment-refractory nAMD. The treatment index, outcomes, and adherence to treatment were compared between both treatment regimens.

RESULTS

Sixty-two patients (67 eyes) met inclusion criteria. There was no change in the treatment index (0.65 versus 0.66, P = 0.650) or the number of nonadherent events (33 versus 36, P = 0.760) after the switch from IVB/IVR to IVA. Central macular thickness (CMT) increased 7.7%±13.8% in eyes that had a nonadherent event (283±69 µm to 304±75 µm after resuming care, P = 0.039). There was no short-term impact on visual acuity (VA) for this subset of eyes (0.387±0.202 LogMAR versus 0.365±0.156 LogMAR, P = 0.636). Patients who had nonadherent events ended the study with similar VA compared with patients who had no treatment lapses (0.370±0.616 LogMAR versus 0.337±0.638 LogMAR, P = 0.843).

CONCLUSION

Switching from IVB/ IVR to IVA for treatment-refractory nAMD in a real-world setting does not reduce the treatment index or increase adherence to treatment. Although there were short-term anatomical effects resulting from missed treatments, VA remained stable.

Current and Novel Therapeutic Approaches for Treatment of Neovascular Age-Related Macular Degeneration

Age-related macular degeneration AMD is one of the leading causes of blindness in the elderly population. An advanced form of AMD known as neovascular AMD (nAMD) is implicated as the main attributor of visual loss among these patients. The hallmark feature of nAMD is the presence of neovascular structures known as choroidal neovascular membranes (CNVs), along with fluid exudation, hemorrhages, and subretinal fibrosis. These pathological changes eventually result in anatomical and visual loss. A type of proangiogenic factor known as vascular endothelial growth factor (VEGF) has been known to mediate the pathological process behind nAMD. Therefore, therapy has transitioned over the years from laser therapy that ablates the lesions to using Anti-VEGF to target the pathology directly. In this work, we provide an overview of current and emerging therapies for the treatment of nAMD. Currently approved Anti-VEGF agents include ranibizumab, aflibercept, and brolucizumab. Bevacizumab, also an Anti-VEGF agent, is used to manage nAMD even though this is an off-label use. While Anti-VEGF agents have provided a favorable prognosis for nAMD, they are associated with a substantial financial burden for patients and the healthcare system, due to their high cost as well as the need for frequent repeat treatments and visits. Emerging therapies and studies aim to extend the intervals between required treatments and introduce new treatment modalities that would improve patients’ compliance and provide superior results.

Interferon γ neutralization reduces blood pressure, uterine artery resistance index, and placental oxidative stress in placental ischemic rats

Preeclampsia (PE) is characterized by maternal hypertension, intrauterine growth restriction, and increased cytolytic natural killer cells (cNKs), which secrete interferon γ (IFNγ). However, the precise role of IFNγ in contributing to PE pathophysiology remains unclear. Using the reduced uterine perfusion pressure (RUPP) rat model of placental ischemia, we tested the hypothesis that neutralization of IFNγ in RUPPs will decrease placental reactive oxygen species (ROS) and improve vascular function resulting in decreased MAP and improved fetal growth. On gestation day (GD) 14, the RUPP procedure was performed and on GDs 15 and 18, a subset of normal pregnant rats (NP) and RUPP rats were injected with 10 μg/kg of an anti-rat IFNγ monoclonal antibody. On GD 18, uterine artery resistance index (UARI) was measured via Doppler ultrasound and on GD 19, mean arterial pressure (MAP) was measured, animals were euthanized, and blood and tissues were collected for analysis. Increased MAP was observed in RUPP rats compared with NP and was reduced in RUPP + anti-IFNγ. Placental ROS was also increased in RUPP rats compared with NP rats and was normalized in RUPP + anti-IFNγ. Fetal and placental weights were reduced in RUPP rats, but were not improved following anti-IFNγ treatment. However, UARI was elevated in RUPP compared with NP rats and was reduced in RUPP + anti-IFNγ. In conclusion, we observed that IFNγ neutralization reduced MAP, UARI, and placental ROS in RUPP recipients. These data suggest that IFNγ is a potential mechanism by which cNKs contribute to PE pathophysiology and may represent a therapeutic target to improve maternal outcomes in PE.

Live In-Vivo Neuroimaging Reveals the Transport of Lipophilic Cargo Through the Blood-Retina Barrier with Modified Amphiphilic Poly-N-Vinylpyrrolidone Nanoparticles

The blood-retina barrier (BRB), analogous to the blood-brain barrier, is a major hurdle for the passage of drugs from the blood to the central nervous system. Here, we designed polymeric nanoparticles from amphiphilic poly-/V-vinylpyrrolidone (Amph-PVP NPs) as a new carrier-system and investigated their ability to pass the BRB using a live In-Vivo neuroimaging system for the retina in rats and ex-vivo wholemounted retinae preparation. Amph-PVP NPs were loaded with hydrophobic fluorescent markers as a surrogate for hydrophobic drugs. Linking these NPs with the hydrophobic fluorescence marker Carboxyfluorescein-succinimidyl-ester (CFSE) to the surface, induced the passage of the cargo into the retina tissue. In particular, we observed a substantial internalization of the CFSE-linked NPs into blood cells. We propose surface- modified Amph-PVP NPs as a potential new nano-carrier platform to target posterior eye and potentially brain diseases while camouflaged by blood cells.

Relapse of pathological angiogenesis: functional role of the basement membrane and potential treatment strategies

Blinding eye diseases such as corneal neovascularization, proliferative diabetic retinopathy, and age-related macular degeneration are driven by pathological angiogenesis. In cancer, angiogenesis is key for tumor growth and metastasis. Current antiangiogenic treatments applied clinically interfere with the VEGF signaling pathway-the main angiogenic pathway-to inhibit angiogenesis. These treatments are, however, only partially effective in regressing new pathologic vessels, and the disease relapses following cessation of treatment. Moreover, the relapse of pathological angiogenesis can be rapid, aggressive and more difficult to treat than angiogenesis in the initial phase. The manner in which relapse occurs is poorly understood; however, recent studies have begun to shed light on the mechanisms underlying the revascularization process. Hypotheses have been generated to explain the rapid angiogenic relapse and increased resistance of relapsed disease to treatment. In this context, the present review summarizes knowledge of the various mechanisms of disease relapse gained from different experimental models of pathological angiogenesis. In addition, the basement membrane-a remnant of regressed vessels-is examined in detail to discuss its potential role in disease relapse. Finally, approaches for gaining a better understanding of the relapse process are discussed, including prospects for the management of relapse in the context of disease.

Sustained suppression of VEGF for treatment of retinal/choroidal vascular diseases

Neovascular age-related macular degeneration (NVAMD) is the most prevalent choroidal vascular disease, and diabetic retinopathy (DR) and retinal vein occlusion (RVO) are the most prevalent retinal vascular diseases. In each of these, hypoxia plays a central role by stabilizing hypoxia-inducible factor-1 which increases production of vascular endothelial growth factor (VEGF) and other hypoxia-regulated gene products. High VEGF causes excessive vascular permeability, neovascularization, and in DR and RVO, promotes closure of retinal vessels exacerbating hypoxia and creating a positive feedback loop. Hence once VEGF expression is elevated it tends to remain elevated and drives disease progression. While other hypoxia-regulated gene products also contribute to pathology in these disease processes, it is remarkable how much pathology is reversed by selective inhibition of VEGF. Clinical trials have demonstrated outstanding visual outcomes in patients with NVAMD, DR, or RVO from frequent intraocular injections of VEGF-neutralizing proteins, but for a variety of reasons injection frequency has been substantially less in clinical practice and visual outcomes are disappointing. Herein we discuss the rationale, preclinical, and early clinical results of new approaches that provide sustained suppression of VEGF. These approaches will revolutionize the management of these prevalent retinal/choroidal vascular diseases.

Loss to Follow-up Among Patients With Neovascular Age-Related Macular Degeneration Who Received Intravitreal Anti-Vascular Endothelial Growth Factor Injections

Importance

Loss to follow-up (LTFU) after anti-vascular endothelial growth factor (anti-VEGF) injections increases the risk of vision loss among patients with neovascular age-related macular degeneration (nAMD).

Objective

To report rates of LTFU among patients with nAMD after anti-VEGF injections and to identify risk factors associated with LTFU in this population.

Design, Setting, and Participants

This retrospective cohort study of data from 9007 patients who received anti-VEGF injections for treatment of nAMD was performed at an urban, private retina practice with multiple locations from April 1, 2012, to January 12, 2016.

Main Outcomes and Measures

Rates of LTFU after anti-VEGF injections. Loss to follow-up was defined as receipt of 1 or more injections with no subsequent follow-up visit within 12 months.

Results

Among the 9007 patients (mean [SD] age, 81.2 [8.8] years; 5917 [65.7%] female; 7905 [87.8%] white), 2003 (22.2%) were LTFU. Odds of LTFU were greater among patients 81 to 85 years of age (odds ratio [OR], 1.58; 95% CI, 1.38-1.82; P < .001), 86 to 90 years of age (OR, 2.29; 95% CI, 2.00-2.62; P < .001), and more than 90 years of age (OR, 3.31; 95% CI, 2.83-3.86; P < .001) compared with patients 80 years of age and younger. Odds of LTFU among African American patients (OR, 1.47; 95% CI, 1.00-2.16; P = .05), Asian patients (OR, 2.63; 95% CI, 1.71-4.03; P < .001), patients of other race (OR, 3.07; 95% CI, 1.38-6.82; P = .006), and patients of unreported race (OR, 2.29; 95% CI, 1.96-2.68; P < .001) were greater than odds of LTFU among white patients. Odds of LTFU were greater among patients with regional adjusted gross income of $50 000 or less (OR, 1.52; 95% CI, 1.30-1.79; P < .001), $51 000 to $75 000 (OR, 1.35; 95% CI, 1.17-1.56; P < .001), and $76 000 to $100 000 (OR, 1.28; 95% CI, 1.08-1.50; P = .004) compared with patients with incomes greater than $100 000. Odds of LTFU for patients living 21 to 30 miles (OR, 1.33; 95% CI, 1.05-1.69; P = .02) and more than 30 miles (OR, 1.55; 95% CI, 1.28-1.88; P < .001) from clinic were greater compared with patients who lived 10 miles or less from the clinic. Odds of LTFU were greater among patients who received unilateral injections (OR, 1.44; 95% CI, 1.28-1.61; P < .001) than among patients who received bilateral injections.

Conclusions and Relevance

We found a high rate of LTFU after anti-VEGF injections among patients with nAMD and identified multiple risk factors associated with LTFU among this population. Although our results may not be generalizable, data on LTFU in a clinical practice setting are needed to understand the scope of the problem so that interventions may be designed to improve outcomes.

Bevacizumab in Wet AMD treatment: A tribute to the thirteen years of experience from the beginning of the anti-VEGF era in Romania

This study aimed to identify and describe anatomical and functional changes on short (1–3 months) and medium (6–12 months) term after intravitreal injections of bevacizumab (Avastin, Genentech) in patients with choroidal neovascularization (CNV) in the context of exudative form of age-related macular degeneration (AMD). We performed a retrospective, analytical, interventional study, based on a series of cases with exudative form of AMD, which also comprised a prospective component related to the inclusion and treatment of the patients with a very new interventional method for that time (2006) and the follow-up of the effects of intravitreal injection of bevacizumab (1.25 mg) therapy in three monthly doses for short (1–3 months) and medium (6–18 months) periods of time. The follow-up of these patients was made by determining visual acuity (VA) as best corrected visual acuity (BCVA) at baseline and at every visit, slit lamp examination with contact or noncontact lenses each time, and optical coherence tomography and/or angiofluorography, applied only for certain patients, at various times of the study. In total, 376 intravitreal injections were administered to 117 eyes of 96 patients. The VA improved in the assessment of 3 months in 77 eyes (66%), either subjective (by the patient) or objectively quantified (by the physician). In 40 eyes (34%), there was no change in VA. In patients for whom optical coherence tomography could be performed, a significant reduction of the macula's thickness was found. The use of bevacizumab in subretinal neovascular membrane treatment is effective and safe on short and medium term, with the improvement of BCVA and reduction of macular edema in a significant number of cases.

Lessons Learned From Avastin and OCT-The Great, the Good, the Bad, and the Ugly: The LXXV Edward Jackson Memorial Lecture

PURPOSE

To describe the synergistic benefits and cost savings from the use of optical coherence tomography (OCT) and vascular endothelial growth factor (VEGF) inhibitors, particularly intravitreal bevacizumab, in the treatment of exudative age-related macular degeneration (AMD).

DESIGN

Retrospective literature review and personal perspective.

METHODS

Retrospective literature review and personal perspective.

RESULTS

The introduction of the first clinically useful OCT instrument coincided with early-phase clinical trials of a drug that would become known as ranibizumab. OCT provided a noninvasive imaging strategy that unambiguously showed the macular fluid associated with exudative AMD and the ability of anti-VEGF therapy to resolve this fluid with concomitant visual acuity improvement. Clinicians came to embrace the use of OCT imaging as the basis for dosing with anti-VEGF drugs, rather than the fixed-interval dosing that was the standard in clinical trials and recommended by industry after approval. But, before ranibizumab was approved for the treatment of exudative AMD, intravenous bevacizumab was approved to treat cancer. Both drugs shared a common molecular lineage, and this led to a clinical trial using intravenous bevacizumab for the treatment of exudative AMD. Intravenous bevacizumab resulted in visual acuity and OCT improvements similar to ranibizumab, and this observation soon led to the intravitreal use of bevacizumab in 2005. Fortuitously, both ranibizumab and bevacizumab were packaged at similar molar concentrations, so similar volumes of both drugs when injected into an eye would result in similar anti-VEGF activity. With ranibizumab not yet commercially available, intravitreal bevacizumab rapidly became adopted worldwide for the treatment of VEGF-driven ocular diseases. Despite numerous attempts by industry and anonymous sources to discredit and prevent its use, bevacizumab spread globally owing to its availability; its low treatment cost, which was $5.50 per 1 mg in the United States; the evidence of efficacy based on OCT imaging and vision improvement; and its perceived safety. In the United States alone, the use of OCT-guided therapy and the use of bevacizumab for the treatment of exudative AMD has saved Medicare over $40 billion since 2008.

CONCLUSIONS

The rapid adoption of OCT-guided therapy and the use of intravitreal bevacizumab by the global retinal community has prevented blindness from exudative and neovascular ocular diseases worldwide while saving healthcare providers and patients billions of dollars.

Effects of intravitreal bevacizumab in Gram-positive and Gram-negative models of ocular inflammation

BACKGROUND

Exogenous endophthalmitis is a potential complication of intraocular surgery and frequently results in visual impairment. Current treatment involves administration of intravitreal (IVT) antibiotics with or without vitrectomy surgery. Evidence for the use of adjunctive anti-inflammatory agents is conflicting. We set out to determine if bevacizumab, a humanized monoclonal IgG1 antibody targeted against vascular endothelial growth factor (VEGF), has anti-inflammatory properties in experimental models of Gram-positive and Gram-negative inflammation.

METHODS

BALB/c mice were subjected to lipopolysaccharide- (LPS) or peptidoglycan- (PGN) induced ocular inflammation and treated with IVT bevacizumab. Iris microvasculature was imaged 6 hours following irritant/treatment using intravital microscopy (IVM) before the mice were euthanized and the eyes were enucleated immediately post-mortem. Following enucleation, levels of VEGF and 23 cytokines and chemokines (IL-1α, IL-1β, IL-2, IL-3, IL-4, IL-5, IL-6, IL-10, IL-12 (p40), IL-12 (p70), IL-13, IL-17, TNF, KC, G-CSF, GM-CSF, Eotaxin, INF-γ, MCP-1, MIP-1α, MIP-1β, RANTES) were quantified using a multiplex assay.

RESULTS

Levels of VEGF were significantly increased during the inflammatory response, triggered by either PGN or LPS. Both the adherence of leukocytes to the iris vascular endothelium and the levels of pro-inflammatory cytokines and chemokines were significantly increased following administration of either irritant. Treatment with bevacizumab decreased levels of leukocyte adherence in LPS-treated eyes, however, not in PGN-treated eyes. Conversely, bevacizumab treatment decreased levels of cytokines and chemokines (TNF, IL-6, MCP-1, MIP-1α, MIP-1β, RANTES, KC) in PGN-treated eyes, however, not in LPS-treated eyes.

CONCLUSIONS

Within a 6-hour window bevacizumab had anti-inflammatory actions that were distinct in both Gram-positive (PIU) and Gram-negative (EIU) models, respectively. Given our findings, this would suggest that bevacizumab may have utility as an adjunctive therapy to IVT antibiotics and vitrectomy in the management of exogenous endophthalmitis.

EFFECTS OF INTRAVITREAL RANIBIZUMAB AND BEVACIZUMAB ON THE RETINAL VESSEL SIZE IN DIABETIC MACULAR EDEMA

PURPOSE

The goal of this study was to assess the effects of a single injection of intravitreal ranibizumab (RAN) or bevacizumab (BEV) on the retinal vessel size in eyes with diabetic macular edema.

MATERIALS AND METHODS

In total, 32 patients were enrolled in the RAN group, and 30 patients were included in BEV group. Each of these groups was also subdivided into two others groups: a study group and a control group. The study groups were composed of the injected eyes, whereas the noninjected fellow eyes served as the control groups. The patients underwent complete ophthalmic examinations, including optical coherence tomography and fundus fluorescein angiography, and the primary outcome measures included the central retinal artery equivalent, central retinal vein equivalent, and artery-to-vein ratio.

RESULTS

In the RAN study group (n = 32), the preinjection mean central retinal artery equivalent (175.42 μm) decreased to 169.01 μm after 1 week, and to 167.47 μm after 1 month (P < 0.001), whereas the baseline central retinal vein equivalent (235.29 μm) decreased initially to 219.90 μm after 1 week, and to 218.36 μm after 1 month (P < 0.001). In the BEV study group (n = 30), the preinjection central retinal artery equivalent (150.21 μm) decreased to 146.25 μm after 1 week, and to 145.89 μm after 1 month (P < 0.001); whereas the baseline central retinal vein equivalent (211.87 μm) decreased initially to 204.59 μm after 1 week and was 205.24 μm after 1 month (P < 0.001). The preinjection artery-to-vein ratio values changed significantly (P = 0.001) after 1 week and after 1 month in the RAN group, but no significant alteration in the artery-to-vein ratio was observed in the BEV group (P = 0.433). In both the RAN (n = 32) and BEV (n = 30) control groups, none of the 3 parameters changed throughout the study period, when compared with the baseline.

CONCLUSION

The results of this study showed that both RAN and BEV injections significantly constricted the retinal blood vessel diameters.

Ocular delivery of proteins and peptides: Challenges and novel formulation approaches

The impact of proteins and peptides on the treatment of various conditions including ocular diseases over the past few decades has been advanced by substantial breakthroughs in structural biochemistry, genetic engineering, formulation and delivery approaches. Formulation and delivery of proteins and peptides, such as monoclonal antibodies, aptamers, recombinant proteins and peptides to ocular tissues poses significant challenges owing to their large size, poor permeation and susceptibility to degradation. A wide range of advanced drug delivery systems including polymeric controlled release systems, cell-based delivery and nanowafers are being exploited to overcome the challenges of frequent administration to ocular tissues. The next generation systems integrated with new delivery technologies are anticipated to generate improved efficacy and safety through the expansion of the therapeutic target space. This review will highlight recent advances in formulation and delivery strategies of protein and peptide based biopharmaceuticals. We will also describe the current state of proteins and peptides based ocular therapy and future therapeutic opportunities.

Systemic Bevacizumab for Retinal Angiomatous Proliferation Associated with Retinal Pigment Epithelial Detachment

Purpose

To report the off-label use of systemic bevacizumab in a patient with stage 3 retinal angiomatous proliferation (RAP) associated with a vascularized pigmented epithelium detachment (PED).

Methods

Interventional case report.

Results

The patient was treated with systemic bevacizumab after obtaining fully informed consent. At 3 months post-treatment, the authors observed an improvement of one line (seven letters) in visual acuity and total regression of the PED on ocular coherence tomography. No adverse effects were observed.

Conclusions

Systemic bevacizumab therapy appears to be safe and effective in the treatment of RAP associated with PED during this short follow-up period of 3 months. The authors recommend a large trial with long-term follow-up to confirm the promising results and evaluate the occurrence of adverse effects associated with systemic bevacizumab.

Evaluation of effect of bevacizumab on central subfield macular thickness in the injected and contralateral (untreated) eye of patients with bilateral diabetic macular oedema

Purpose

Antivascular endothelial growth factor (anti-VEGFs)—bevacizumab is routinely utilised for the treatment of diabetic macular oedema (DME). We plan to evaluate the impact of bevacizumab on the central subfield macular thickness (CSMT) of the treated and untreated eye.

Methods

A sequential group of patients with bilateral DME who were treated with unilateral bevacizumab injection were assessed preinjection and postinjection by Spectral Domain-Optical Coherence Tomography (SD-OCT) by CSMT.

Results

Thirty-one patients, 20 male and 11 female, were evaluated. Seven patients had type 1 diabetes mellitus and 24 had type 2 diabetes mellitus. In regard to the duration of disease, 23 patients had diabetes for more than 10 years, seven patients had the condition for 5–10 years and one patient for more than 5 years. Mean age of the patients was 60.48 years (SD±7.13) with the range of 46–72 years. Mean follow-up was 28 days (range 26–35 days). The eyes which received intravitreal injection had median CSMT of 473.2 µm(range 321–566 µm). The CSMT of the contralateral eye had median of 347.6 µm (range 357–437 µm). A median reduction of −132 µm (range 93–156 µm) could be observed in the treated eye and −18 µm (range 15–22) in the untreated eye after treatment. Our study also found that eyes with greater CSMT, when injected with bevacizumab, produced higher responses in the contralateral eye (R² 0.538, P<0.05).

Conclusions

Patients with bilateral DME treated with bevacizumab in one eye produced a bilateral response. Eyes with greater CSMT due to DME elicited higher levels of response in the untreated eye.

Intra-individual variability and circadian rhythm of vascular endothelial growth factors in subjects with normal glucose tolerance and type 2 diabetes

Increased levels of systemic vascular endothelial growth factors (VEGFs) in patients with diabetes are associated with increased risk of microvessel disease. On the other hand, low VEGF levels after intravitreal antibody application may be associated with acute cardiovascular complications and treatment failure. Individual levels of systemic VEGF vary in a wide range depending on analytical methods and quality of diabetes control. So far only limited information exists on intraindividual fluctuations over longer periods and circadian rhythms. We analysed the intraindividual variance of VEGF-A, VEGF-C and placental growth factor (PLGF) in CTAD (citrate-theophylline-adenine-dipyridamol) plasma as well as VEGF-A in serum over a period of 6 months in patients with stable controlled type 2 diabetes (10 M, 10 F) and age and sex matched subjects with normal glucose tolerance (NGT). Furthermore, circadian levels of VEGFs were controlled hourly from 7:30 a.m. to 7:30 p.m. under standardized metabolic ward conditions. In addition, the relationship to metabolic, hormonal and inflammatory biomarkers was analyzed. VEGF-A, VEGF-C and PLGF remained stable in plasma and VEGF-A in serum over 6 months in both groups. No circadian change was observed in VEGF-A serum and plasma concentrations. A minor decrease of VEGF-C plasma levels was evident after 5 p.m. in both groups and a significant peak of PLGF concentrations occurred after lunch, which was more pronounced in T2DM. In multivariate analysis, only serum VEGF-A correlated to diabetes duration, whereas VEGF-C only correlated to HbA1c and fasting blood glucose. We did not observe significant intraindividual variances for VEGF-A in serum and VEGF-A, VEGF-C and PLGF in CTAD plasma over a period of 6 months. Taken together, a single morning measurement of systemic VEGF levels after 7:30 am appears to be a reliable parameter for the individual risk associated with abnormal VEGF concentrations in blood.

Trial Registration: NCT02325271

[Analysis of cardiovascular diseases after the upload phase with intravitreal ranibizumab and bevacizumab in patients with exudative age-related macular degeneration]

BACKGROUND

The intravitreal administration of vascular endothelial growth factor (VEGF) inhibitors is the gold standard in the treatment of exudative age-related macular degeneration (AMD) but the possible risks of systemic, particularly cardiovascular side effects are still discussed.

PATIENTS AND METHODS

We prospectively followed 111 patients at the University Hospital in Göttingen with exudative AMD and intravitreal ocular treatment with bevacizumab and ranibizumab during the upload phase of 3 months using a questionnaire for documentation of possible cardiovascular events.

RESULTS

In 5 out of 111 patients angina pectoris was observed and in 6 patients the antihypertensive medication had to be increased. No differences were found between bevacizumab and ranibizumab. A patient with pre-existing cardiovascular diseases suffered a stroke in the upload phase but no thromboembolic events were observed in the other patients.

CONCLUSION

In this small but prospective clinical study no increased risk for cardiovascular events during the upload phase of the VEGF inhibitors ranibizumab and bevacizumab could be detected when taking the age and pre-existing cardiovascular diseases into consideration.

[What can anti-VEGF therapy achieve in clinical routine? : Effectiveness of anti-VEGF therapy in patients with macular diseases in clinical routine on 1492 eyes in Austria]

BACKGROUND

The aim of this user observational study was to illustrate the effectiveness of intravitreal operative medication administration (IVOM) in the clinical routine.

DESIGN

A monocentric, single arm, prospective study.

MATERIAL AND METHODS

Included in this study were all patients in whom a macular edema was diagnosed during an ophthalmological examination at the Barmherzigen Brüdern Hospital in Linz from November 2012 to August 2014 and who were treated as outpatients or day clinic patients with IVOM using anti-vascular endothelial growth factor (VEGF). The parameters measured during the clinical routine were as follows: best corrected visual acuity (BCVA) using the early treatment diabetic retinopathy study (ETDRS) chart, central optical coherence tomography (OCT) thickness, diagnosis and possible prior treatment with IVOM. Following diagnosis, the IVOM was administered in 6‑week intervals and a final control with measurement of the named parameters (approximately 19 weeks after diagnosis). If edema was present a further 3‑stage series (19 weeks) was initiated. In the case of a "dry" condition the further controls were performed by a private practitioner and the patient only presented again if macular edema reoccurred. A control of the patients with "dry" results at regular intervals was not planned.

RESULTS

A total of 1492 eyes from 1184 patients with an average age of 75.6 ± 11.3 years were included in the study according to the abovenamed criteria. Choroidal neovascularization (CNV) with age-related macular degeneration (AMD) was diagnosed in 879 eyes and 314 eyes were treated for diabetic macular edema (DME). Of the eyes 122 (8.2%) were affected by branch vein thrombosis (AVT) and 63 (4.2%) from central vein thrombosis (CVT). In 47 (3.2%) eyes macular edema with myopic CNV (mCNV) was detected and 67 eyes (4.5%) were not further classified under "others". In all groups a gain in letters could be achieved in the EDTRS chart even after the first IVOM series: AMD + 3.4, DME + 1.3, AVT + 6.1, CVT + 10.1 and mCNV + 7.0. Patients who were treated with IVOM for the first time showed on average a better response than those previously treated with IVOM.

CONCLUSION

As in many other studies our data also underline the necessity for intravitreal injections for treatment of macular edema. Even if a 6‑week interval does not nowadays correspond to the current guidelines, we could achieve a stabilization of vision and do not shy away from comparison with large studies, such as the Marina study. In order to provide the increasing numbers of patients the best treatment in the future, an attempt at targeted implementation of resources must be made and if necessary symptoms which can be conservatively treated should be delegated to the private sector.

Diabetic macular edema, retinopathy and age-related macular degeneration as inflammatory conditions

Diabetic macular edema (DME) and diabetic retinopathy (DR) are complications affecting about 25% of all patients with long-standing type 1 and type 2 diabetes mellitus and are a major cause of significant decrease in vision and quality of life. Age-related macular degeneration (AMD) is not uncommon, and diabetes mellitus affects the incidence and progression of AMD through altering hemodynamics, increasing oxidative stress, accumulating advanced glycation end products, etc. Recent studies suggest that DME, DR and AMD are inflammatory conditions characterized by a breakdown of the blood-retinal barrier, inflammatory processes and an increase in vascular permeability. Key factors that seem to have a dominant role in DME, DR and AMD are angiotensin II, prostaglandins and the vascular endothelial growth factor and a deficiency of anti-inflammatory bioactive lipids. The imbalance between pro- and anti-inflammatory eicosanoids and enhanced production of pro-angiogenic factors may initiate the onset and progression of DME, DR and AMD. This implies that bioactive lipids that possess anti-inflammatory actions and suppress the production of angiogenic factors could be employed in the prevention and management of DME, DR and AMD.

Anti-Vascular Endothelial Growth Factor Agents in the Treatment of Retinal Disease: From Bench to Bedside

The association of retinal hypoxia with retinal neovascularization has been recognized for decades, causing Michaelson to postulate in 1948 that a factor secreted by hypoxic retina was involved. The isolation of vascular endothelial growth factor (VEGF), characterization of its angiogenic activity, and demonstration that its expression was increased in hypoxic tissue made it a prime candidate. Intraocular levels of VEGF are elevated in patients with retinal or iris neovascularization, and VEGF-specific antagonists markedly suppress retinal neovascularization in mice and primates with ischemic retinopathy. Vascular endothelial growth factor antagonists also suppress choroidal neovascularization, and transgenic expression of VEGF in the retina of mice causes subretinal neovascularization. Clinical trials using a VEGF antagonist that blocks all isoforms of VEGF-A in patients with neovascular age-related macular degeneration (nAMD) demonstrated dramatic benefit. Similar results have been obtained with 2 other VEGF antagonists. Retinal hypoxia also contributes to diabetic macular edema (DME), and because of the absence of good animal models, small clinical trials were used to test the role of VEGF. The results clearly implicated VEGF as a major contributor to DME and have been confirmed by several large multicenter trials. A similar strategy demonstrated that VEGF is a major contributor to macular edema resulting from retinal vein occlusion, also confirmed in multicenter trials. Secondary outcomes in these large clinical trials have shown that VEGF inhibition improves retinal hemorrhages, retinal vessel closure, and progression of nonproliferative diabetic retinopathy. Anti-VEGF agents also provide therapeutic benefits in proliferative diabetic retinopathy. Thus, the development of VEGF antagonists has revolutionized the treatment of nAMD, diabetic retinopathy, and other ischemic retinopathies, but in many patients, the upregulation of VEGF is prolonged. Although the molecular signaling by which hypoxia and some other insults lead to upregulation of VEGF has been elucidated, it has not yet led to a treatment that reliably reduces the production of VEGF, necessitating continued neutralization by repeated intraocular injections of VEGF antagonists in many patients. The next horizon in the evolution of anti-VEGF therapy is the development of longer-acting agents or delivery platforms that provide sustained neutralization with fewer injections.

Optical Coherence Tomography and the Development of Antiangiogenic Therapies in Neovascular Age-Related Macular Degeneration

PURPOSE

To explain the pivotal role optical coherence tomography (OCT) imaging had in the development of antiangiogenic therapies for the treatment of neovascular age-related macular degeneration (nvAMD).

METHODS

A historical literature review was combined with personal perspectives from the introduction of OCT imaging and the early clinical use of vascular endothelial growth factor (VEGF) inhibitors.

RESULTS

At the time that OCT emerged, the gold standard for imaging of nvAMD was fluorescein angiography (FA), a time-consuming, dye-based, invasive technique that provided en face images of the retina and was used to characterize leakage, perfusion status, and the types of macular neovascularization (MNV). In comparison, OCT imaging was a fast, safe, noninvasive technique that complemented FA imaging by providing cross-sectional images of the macula. OCT was able to visualize and quantify the macular fluid that was associated with the presence of excess VEGF, which was identified by intraretinal fluid, subretinal fluid, and fluid under the retinal pigment epithelium (RPE). Clinicians quickly appreciated the benefits of OCT imaging for following macular fluid after anti-VEGF therapy. By observing the qualitative and quantitative changes in macular fluid depicted by OCT imaging, clinicians were empowered to compare anti-VEGF drugs and move from fixed-dosing regimens to patient-specific dosing strategies requiring fewer injections.

CONCLUSIONS

Optical coherence tomography imaging was adopted as a VEGF-meter, a method to detect excess VEGF, and evolved to become the gold standard imaging strategy for diagnosing nvAMD, assessing treatment responses to anti-VEGF drugs, deciding when to re-treat, and evaluating disease progression.

A randomised controlled trial to assess the clinical effectiveness and cost-effectiveness of alternative treatments to Inhibit VEGF in Age-related choroidal Neovascularisation (IVAN)

BACKGROUND

Bevacizumab (Avastin®, Roche), which is used in cancer therapy, is the 'parent' molecule from which ranibizumab (Lucentis®, Novartis) was derived for the treatment of neovascular age-related macular degeneration (nAMD). There were reports in the literature on the effectiveness of bevacizumab in treating nAMD, but no trials. The cost per dose of bevacizumab is about 5-10% that of ranibizumab. This trial was a head-to-head comparison of these two drugs.

OBJECTIVE

To compare the clinical effectiveness and cost-effectiveness of ranibizumab and bevacizumab, and two treatment regimens, for nAMD.

DESIGN

Multicentre, factorial randomised controlled trial with within-trial cost-utility and cost-minimisation analyses from the perspective of the UK NHS. Participants, health professionals and researchers were masked to allocation of drug but not regimen. Computer-generated random allocations to combinations of ranibizumab or bevacizumab, and continuous or discontinuous regimen, were stratified by centre, blocked and concealed.

SETTING

Twenty-three ophthalmology departments in NHS hospitals.

PARTICIPANTS

Patients ≥ 50 years old with active nAMD in the study eye with best corrected distance visual acuity (BCVA) ≥ 25 letters measured on a Early Treatment of Diabetic Retinopathy Study (ETDRS) chart. Previous treatment for nAMD, long-standing disease, lesion diameter > 6000 µm, thick blood at the fovea and any other confounding ocular disease were exclusion criteria. One eye per participant was studied; the fellow eye was treated according to usual care, if required.

INTERVENTIONS

Ranibizumab and bevacizumab were procured commercially. Doses were ranibizumab 0.5 mg or bevacizumab 1.25 mg. The repackaged bevacizumab was quality assured. All participants were treated at visits 0, 1 and 2. Participants randomised to the continuous regimen were treated monthly thereafter. Participants randomised to the discontinuous regimen were not retreated after visit 2 unless pre-specified criteria for active disease were met. If retreatment was needed, monthly injections over 3 months were mandated.

MAIN OUTCOME MEASURES

The primary outcome was BCVA. The non-inferiority margin was 3.5 letters. Secondary outcomes were contrast sensitivity; near visual acuity; reading index; neovascular lesion morphology; generic and disease-specific patient-reported outcomes, including macular disease-specific quality of life; survival free from treatment failure; resource use; quality-adjusted life-years (QALYs); and development of new geographic atrophy (GA) (outcome added during the trial). Results are reported for the study eye, except for patient-reported outcomes.

RESULTS

Between 27 March 2008 and 15 October 2010, 610 participants were allocated and treated (314 ranibizumab, 296 bevacizumab; at 3 months, 305 continuous, 300 discontinuous). After 2 years, bevacizumab was neither non-inferior nor inferior to ranibizumab [-1.37 letters, 95% confidence interval (CI) -3.75 to +1.01 letters] and discontinuous treatment was neither non-inferior nor inferior to continuous treatment (-1.63 letters, 95% CI -4.01 to +0.75 letters). Lesion thickness at the fovea was similar by drug [geometric mean ratio (GMR) 0.96, 95% CI 0.90 to 1.03; p = 0.24] but 9% less with continuous treatment (GMR 0.91, 95% CI 0.85 to 0.97; p = 0.004). Odds of developing new GA during the trial were similar by drug [odds ratio (OR) 0.87, 95% CI 0.61 to 1.25; p = 0.46] but significantly higher with continuous treatment (OR 1.47, 95% CI 1.03 to 2.11; p = 0.033). Safety outcomes did not differ by drug but mortality was lower with continuous treatment (OR 0.47, 95% CI 0.22 to 1.03; p = 0.05). Continuous ranibizumab cost £3.5M per QALY compared with continuous bevacizumab; continuous bevacizumab cost £30,220 per QALY compared with discontinuous bevacizumab. These results were robust in sensitivity analyses.

CONCLUSIONS

Ranibizumab and bevacizumab have similar efficacy. Discontinuing treatment and restarting when required results in slightly worse efficacy. Safety was worse with discontinuous treatment, although new GA developed more often with continuous treatment. Ranibizumab is not cost-effective, although it remains uncertain whether or not continuous bevacizumab is cost-effective compared with discontinuous bevacizumab at £20,000 per QALY threshold. Future studies should focus on the ocular safety of the two drugs, further optimisation of treatment regimens and criteria for stopping treatment.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN92166560.

FUNDING

This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 19, No. 78. See the NIHR Journals Library website for further project information.

Risk of Myocardial Infarction and Stroke With Single or Repeated Doses of Intravitreal Bevacizumab in Age-Related Macular Degeneration

PURPOSE

To examine the risk of myocardial infarction and stroke with single and repeated doses of intravitreal bevacizumab in wet age-related macular degeneration (AMD).

DESIGN

Nested case-control study and retrospective cohort study.

METHODS

setting: Two patient cohorts from British Columbia, Canada.

STUDY POPULATION

Patients with wet AMD.

INTERVENTION

For the cohort study, patients who received the first intravitreal bevacizumab; for the nested case-control study, repeated injections of intravitreal bevacizumab.

MAIN OUTCOME MEASURES

Myocardial infarction for the retrospective cohort study; myocardial infarction and stroke for the nested case-control study.

RESULTS

In the cohort analysis, there were 2564 AMD subjects not on a vascular endothelial growth factor (VEGF) inhibitor and 5644 subjects receiving intravitreal bevacizumab. The rate of myocardial infarction (MI) among bevacizumab users was 11/1000 person-years, compared to 14.9/1000 person-years in nonusers. The adjusted rate ratio (RR) for MI was 0.70 (95% confidence interval [CI]: 0.50-1.00) and 0.74 (0.46-1.20) for the propensity score-adjusted analysis. In the nested case-control analysis there were 7452 new users of VEGF inhibitors, within which there were 313 cases of MI with 3130 matched controls. The adjusted RR for MI among those receiving 3 or more injections compared to those receiving fewer than 3 was 0.71 (95% CI: 0.41-1.22). Also in the nested case-control analysis, the adjusted RR for stroke was 0.81 (95% CI: 0.39-1.65) for those receiving ≥4 injections vs those receiving fewer than 4 injections.

CONCLUSION

Single or repeated doses of intravitreal bevacizumab were not shown to increase the risk of myocardial infarction or stroke in patients with wet AMD.

Comparative safety and tolerability of anti-VEGF therapy in age-related macular degeneration

Neovascular age-related macular degeneration (NVAMD) is one of the leading causes of blindness. Over the last decade, the treatment of NVAMD has been revolutionized by the development of intravitreal anti-vascular endothelial growth factor (VEGF) therapies. Several anti-VEGF medications are used for the treatment of NVAMD. The safety and tolerability of these medications deserve review given the high prevalence of NVAMD and the significant utilization of these medications. Numerous large randomized clinical trials have not shown any definitive differential safety relative to ocular or systemic safety of these medications. Intravitreal anti-VEGF therapy does appear to impact systemic VEGF levels, but the implications of these changes remain unclear. One unique safety concern relates drug compounding and the potential risks of contamination, specifically for bevacizumab. Continued surveillance for systemic safety concerns, particularly for rare events, is merited. Overall, these medications are well tolerated and effective in the treatment of NVAMD.

Current intravitreal pharmacologic therapies for diabetic macular edema

INTRODUCTION

Diabetic retinopathy is the leading cause of vision loss in working-age adults; it is a highly prevalent cause of vision loss overall and has a potent impact on the quality of life in those with diabetes mellitus and public health in general. Diabetic macular edema (DME) is the most common cause of vision loss from diabetic retinopathy. In patients with diabetes mellitus, chronic hyperglycemia leads to activation of the inflammatory cascade and retinal capillary damage that result in microaneurysm formation in the retina. In addition to the possibility of associated ischemia, microaneurysms are hyperpermeable; the resultant loss of the blood-retinal barrier leads to vision loss if consequent edema involves the center of the fovea. The standard of DME therapy for >25 years was focal laser photocoagulation applied to or near the microaneurysms. However, results from clinical trials of intravitreal vascular endothelial growth factor (VEGF) blockers and corticosteroids for the treatment of DME have led to a dramatic paradigm shift away from laser therapy to primary treatment with these pharmacologic agents.

METHODS

Medline literature search of approaches for treating DME.

RESULTS

Intravitreal pharmacologic treatments with anti-VEGF agents and corticosteroids have recently been shown to be superior to laser treatment of DME.

CONCLUSION

The existence of pharmacologic treatment of DME, shown to be superior to laser monotherapy, has created a seismic change in the approach of treatment of these patients. This review provides a summary of the therapies and the rationale regarding the current pharmacologic therapy of DME.

Targeted localized use of therapeutic antibodies: a review of non-systemic, topical and oral applications

Therapeutic antibodies provide important tools in the "medicine chest" of today's clinician for the treatment of a range of disorders. Typically monoclonal or polyclonal antibodies are administered in large doses, either directly or indirectly into the circulation, via a systemic route which is well suited for disseminated ailments. Diseases confined within a specific localized tissue, however, may be treated more effectively and at reduced cost by a delivery system which targets directly the affected area. To explore the advantages of the local administration of antibodies, we reviewed current alternative, non-systemic delivery approaches which are in clinical use, being trialed or developed. These less conventional approaches comprise: (a) local injections, (b) topical and (c) peroral administration routes. Local delivery includes intra-ocular injections into the vitreal humor (i.e. Ranibizumab for age-related macular degeneration), subconjunctival injections (e.g. Bevacizumab for corneal neovascularization), intra-articular joint injections (i.e. anti-TNF alpha antibody for persistent inflammatory monoarthritis) and intratumoral or peritumoral injections (e.g. Ipilimumab for cancer). A range of other strategies, such as the local use of antibacterial antibodies, are also presented. Local injections of antibodies utilize doses which range from 1/10th to 1/100th of the required systemic dose therefore reducing both side-effects and treatment costs. In addition, any therapeutic antibody escaping from the local site of disease into the systemic circulation is immediately diluted within the large blood volume, further lowering the potential for unwanted effects. Needle-free topical application routes become an option when the condition is restricted locally to an external surface. The topical route may potentially be utilized in the form of eye drops for infections or corneal neovascularization or be applied to diseased skin for psoriasis, dermatitis, pyoderma gangrenosum, antibiotic resistant bacterial infections or ulcerated wounds. Diseases confined to the gastrointestinal tract can be targeted directly by applying antibody via the injection-free peroral route. The gastrointestinal tract is unusual in that its natural immuno-tolerant nature ensures the long-term safety of repeatedly ingesting heterologous antiserum or antibody materials. Without the stringent regulatory, purity and clean room requirements of manufacturing parenteral (injectable) antibodies, production costs are minimal, with the potential for more direct low-cost targeting of gastrointestinal diseases, especially with those caused by problematic antibiotic resistant or toxigenic bacteria (e.g. Clostridium difficile, Helicobacter pylori), viruses (e.g. rotavirus, norovirus) or inflammatory bowel disease (e.g. ulcerative colitis, Crohn's disease). Use of the oral route has previously been hindered by excessive antibody digestion within the gastrointestinal tract; however, this limitation may be overcome by intelligently applying one or more strategies (i.e. decoy proteins, masking therapeutic antibody cleavage sites, pH modulation, enzyme inhibition or encapsulation). These aspects are additionally discussed in this review and novel insights also provided. With the development of new applications via local injections, topical and peroral routes, it is envisaged that an extended range of ailments will increasingly fall within the clinical scope of therapeutic antibodies further expanding this market.

IL-18 attenuates experimental choroidal neovascularization as a potential therapy for wet age-related macular degeneration

Age-related macular degeneration (AMD) is the most common form of central retinal blindness globally. Distinct processes of the innate immune system, specifically activation of the NLRP3 inflammasome, have been shown to play a central role in the development of both "dry" and neovascular ("wet") forms of the disease. We show that the inflammatory cytokine interleukin-18 (IL-18) can regulate choroidal neovascularization formation in mice. We observed that exogenous administration of mature recombinant IL-18 has no effect on retinal pigment epithelial (RPE) cell viability, but that overexpression of pro-IL-18 or pro-IL-1β alone can cause RPE cell swelling and subsequent atrophy, a process that can be inhibited by the promotion of autophagy. A direct comparison of local and systemic administration of mature recombinant IL-18 with current anti-VEGF (vascular endothelial growth factor)-based therapeutic strategies shows that IL-18 treatment works effectively alone and more effectively in combination with anti-VEGF therapy and represents a novel therapeutic strategy for the treatment of wet AMD.

Ocular delivery of macromolecules

Biopharmaceuticals are making increasing impact on medicine, including treatment of indications in the eye. Macromolecular drugs are typically given by physician-administered invasive delivery methods, because non-invasive ocular delivery methods, such as eye drops, and systemic delivery, have low bioavailability and/or poor ocular targeting. There is a need to improve delivery of biopharmaceuticals to enable less-invasive delivery routes, less-frequent dosing through controlled-release drug delivery and improved drug targeting within the eye to increase efficacy and reduce side effects. This review discusses the barriers to drug delivery via various ophthalmic routes of administration in the context of macromolecule delivery and discusses efforts to develop controlled-release systems for delivery of biopharmaceuticals to the eye. The growing number of macromolecular therapies in the eye needs improved drug delivery methods that increase drug efficacy, safety and patient compliance.

Bevacizumab and ranibizumab for neovascular age-related macular degeneration: an updated meta-analysis of randomised clinical trials

Purpose

Neovascular age-related macular degeneration (AMD) is the main cause of central vision loss among individuals aged 50 years or older in developed countries. The aim of this study was to review systematically the effect of bevacizumab compared to ranibizumab in patients with AMD at 1 year.

Methods

A systematic review was performed on Medline, Embase, and the Cochrane Library and Trial registers to October 2013. Eligibility criteria for selecting studies were randomised controlled trials (RCT) comparing bevacizumab with ranibizumab in patients with neovascular AMD. Odds ratio (OR) and mean difference (MD) estimates were synthesized under fixed- and random-effects models. Heterogeneity was assessed using the Q statistic and I².

Results

Five RCTs were included, representing 2,686 randomised patients. The meta-analysis confirmed the non-inferiority of bevacizumab compared to ranibizumab for change in visual acuity at 1 year (MD 0.57 letters, −1.80 to 0.66, p = 0.37, I² = 0 %). Better anatomical results were found for ranibizumab. Bevacizumab was associated with a 34 % increase in the number of patients with at least one serious systemic adverse event (OR 1.34, 1.08 to 1.66, p = 0.01, I² = 0 %).

Conclusions

The pooled evidence confirmed that, compared with ranibizumab, bevacizumab was associated with equivalent effects on visual acuity at 1 year and with a higher risk of systemic serious adverse events. The current available data do not show which types of adverse events occur more frequently. In practice, bevacizumab should be used under a risk-management plan until further studies have been carried out to assess accurately the increased risk of systemic adverse events.

Systemic bevacizumab for simultaneous treatment of cancer and choroidal neovascularisation

A 47-year-old woman with a medical history of pseudoxanthoma elasticum and associated choroidal neovascularisation that was successfully managed with intravitreal bevacizumab injections developed non-squamous non-small cell lung carcinoma. The patient's oncological medication regimen included systemic bevacizumab. During the 22 months that the patient received systemic bevacizumab for management of her malignancy, intravitreal bevacizumab injections were held and the patient's visual acuity remained stable and the subretinal space was free of fluid leakage.

Vaccination with a mutated variant of human Vascular Endothelial Growth Factor (VEGF) blocks VEGF-induced retinal neovascularization in a rabbit experimental model

Vascular Endothelial Growth Factor (VEGF) is a key driver of the neovascularization and vascular permeability that leads to the loss of visual acuity of eye diseases like wet age-related macular degeneration, diabetic macular edema, and retinopathy of premature. Among the several anti-VEGF therapies under investigation for the treatment of neovascular eye diseases, our group has developed the vaccine candidate CIGB-247-V that uses a mutated form of human VEGF as antigen. In this work we evaluated if the vaccine could prevent or attenuate VEGF-induced retinal neovascularization in the course of a rabbit eye neovascularization model, based on direct intravitreal injection of human VEGF. Our experimental findings have shown that anti-VEGF IgG antibodies induced by the vaccine were available in the retina blood circulation, and could neutralize in situ the neovascularization effect of VEGF. CIGB-247-V vaccination proved to effectively reduce retinal neovascularization caused by intravitreal VEGF injection. Altogether, these results open the way for human studies of the vaccine in neovascular eye syndromes, and inform on the potential mechanisms involved in its effect.

Intravitreal aflibercept for neovascular age-related macular degeneration

Neovascular age-related macular degeneration (AMD) is the leading cause of legal blindness in patients over the age of 50 in the western world. Intravitreally administered anti-VEGF drugs have been developed to halt neovascular growth in AMD. Randomized trials have demonstrated the excellent safety profile and significant benefit of anti-VEGF therapy in maintaining vision. Aflibercept (Eylea(®); Regeneron, NY, USA) is a soluble decoy receptor against VEGF that offers greater potency and binding affinity than other anti-VEGF drugs. Having received US FDA approval for neovascular AMD in November 2011, aflibercept given every 8 weeks after a loading dose was 'clinically equivalent' and statistically noninferior to the current FDA-approved therapy ranibizumab (Lucentis(®); Genentech, CA, USA), given every 4 weeks. This article discusses the clinical background of AMD, development of aflibercept, results of the clinical trials and the future role of aflibercept in ocular neovascular diseases.

Intravitreal anti-vascular endothelial growth factor therapy for choroidal neovascularization due to Sorsby macular dystrophy

PURPOSE

To report the first case of intravitreal bevacizumab and ranibizumab to treat choroidal neovascularization secondary to Sorsby macular dystrophy.

CASE

A 57-year-old male with metamorphopsia, color vision deficits, and ocular family history of Sorsby macular dystrophy was found to have a choroidal neovascular membrane (CNVM) in his left eye. He was initially treated with intravitreal bevacizumab and had visual acuity improvement and resolution of the subretinal fluid on OCT. After 8 injections, he developed presumed mild inflammation secondary to intravitreal bevacizumab and was switched to combination intravitreal bevacizumab/dexamethasone in his left eye, which consistently demonstrated efficacy in stabilizing his vision and the CNVM without producing intraocular inflammation. The right eye later developed the CNVM and he was started on intravitreal bevacizumab in this eye as well. After 8 injections in the right eye, he experienced a similar inflammatory reaction following intravitreal bevacizumab injections and was switched to combination intravitreal bevacizumab/dexamethasone in the right eye as well. Subsequently, he was switched to intravitreal ranibizumab in the left eye alone, which continued to stabilize his vision and OCT and did not cause an inflammatory reaction as he previously experienced with bevacizumab. After 5 ranibizumab injections, he experienced no inflammatory response that he appeared to have with bevacizumab, but chose to switch back to combination intravitreal bevacizumab and dexamethasone due to financial reasons. Initially, in his clinical course, he experienced consistent visual acuity improvements with intravitreal antivascular endothelial growth factor therapy and continues to enjoy functional vision nearly 7 years after his initial symptoms.

CONCLUSIONS

Intravitreal bevacizumab and ranibizumab demonstrated efficacy in this case in the treatment of CNVM associated with Sorsby macular dystrophy.

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.

A clear cell renal cell carcinoma inhibiting the response to intravitreal antivascular endothelial growth factor therapy in wet age-related macular disease

PURPOSE

Wet age-related macular degeneration (AMD) is an ocular disorder that can be successfully treated with intravitreal antivascular endothelial growth factor (VEGF) therapy. We report a case of incomplete response to intravitreal therapy associated with a clear cell renal cell carcinoma (ccRCC).

METHODS

A 72-year-old male with wet AMD responded poorly to intravitreal bevacizumab and ranibizumab injections. The removal of a ccRCC led to the spontaneous stabilization of the choroidal neovascular lesion. The renal carcinoma was examined for Von Hippel-Lindau (VHL) gene alterations. Immunohistochemical profiling of the hypoxia-inducible factor (HIF) pathway addressing the marker HIF-1α and its downstream targets VEGF, glucose transporter 1 and carbonic anhydrase IX was performed.

RESULTS

Genotyping of the ccRCC revealed the presence of a truncating VHL mutation (p.E134fs*25). Immunohistochemistry displayed HIF pathway target activation and VEGF expression in the ccRCC tumour cells. Following tumour removal, the neovascular lesion remained stable for 6 months without any further anti-VEGF therapy.

CONCLUSION

The somatic VHL mutation correlates with persistent high levels of HIF-1α pathway targets and VEGF expression in the ccRCC. We postulate that this increased VEGF in the tumour and subsequently in the plasma levels could have caused the incomplete response to intravitreal anti-VEGF therapy. Stabilization of the wet AMD following tumour removal indicates that the angiogenic secreting tumour (ccRCC) abrogates the response to VEGF inhibitor therapy. Thus, in cases of poor response to intravitreal anti-VEGF therapy, systemic evaluation including plasma levels of VEGF and/or systemic screening for VEGF-producing tumours should be considered.

The use of comparative effectiveness research to inform policy decisions on the inclusion of bevacizumab for the treatment of macular diseases in Thailand's pharmaceutical benefit package

There is increasing impetus to use pharmaceutical interventions, ie, ranibizumab or bevacizumab, for the treatment of particular macular diseases. This paper describes the evidence and decision-making of the National List of Essential Medicines Committee that recently announced the inclusion of bevacizumab for the treatment of macular diseases in its pharmaceutical benefit package. The findings of a systematic review and meta-analysis in this paper indicate that the intravitreal administration of bevacizumab is superior to nonpharmaceutical treatments for age-related macular degeneration (AMD) and diabetic macular edema (DME), but inconclusive for retinal vein occlusion, given the limited evidence. The study also failed to distinguish among the differences in terms of visual acuity improvement, reduction of central macular thickness, and response to treatment between AMD and DME patients treated with bevacizumab and those treated with ranibizumab. Although bevacizumab was not licensed for AMD and DME, the committee decided to include bevacizumab in the National List of Essential Medicines. It is expected that many patients who are in need of treatment but who are unable to afford the expensive alternative drug, ranibizumab, will be able to receive this effective treatment instead and be prevented from suffering irreversible loss of vision. At the same time, this policy will help generate evidence about the real-life effectiveness and safety profiles of the drug for future policy development in Thailand and other settings.

Ocular Toxicity of Targeted Therapies

Molecularly targeted agents are commonly used in oncology practice, and many new targeted agents are currently being tested in clinical trials. Although these agents are thought to be more specific and less toxic then traditional cytotoxic chemotherapy, they are associated with a variety of toxicities, including ocular toxicity. Many of the molecules targeted by anticancer agents are also expressed in ocular tissues. We reviewed the literature for described ocular toxicities associated with both approved and investigational molecularly targeted agents. Ocular toxicity has been described with numerous approved targeted agents and also seems to be associated with several classes of agents currently being tested in early-phase clinical trials. We discuss the proposed pathogenesis, monitoring guidelines, and management recommendations. It is important for oncologists to be aware of the potential for ocular toxicity, with prompt recognition of symptoms that require referral to an ophthalmologist. Ongoing collaboration between oncologists and ocular disease specialists is critical as the use of molecularly targeted agents continues to expand and novel targeted drug combinations are developed.

Uveitis, the Comparison of Age-Related Macular Degeneration Treatments Trials (CATT), and intravitreal biologics for ocular inflammation

PURPOSE

To provide perspective on the implications of the Comparison of Age-Related Macular Degeneration Treatments Trials (CATT) on intravitreal biologic agents in uveitis and retinal diseases in which ocular inflammatory pathways are central to their pathogenesis.

DESIGN

Interpretative essay.

METHODS

Literature review and interpretation.

RESULTS

Besides the clear importance of CATT from a patient treatment perspective in age-related macular degeneration (AMD), these data highlight the critical relevance of highly specific protein immunotherapies offered with biologic agents. The CATT trial also provides a reminder regarding the importance of rigorous efficacy and safety monitoring required when administering intravitreal biologic therapy. Within the field of uveitis, systemic and local biologics have been used to effectively treat uveitis, targeting pathways implicated in both angiogenesis and inflammation (eg, tumor necrosis factor-α [TNF-α] and interleukin-2 pathways), and research on intravitreal biologic therapy for uveitis and AMD will continue to expand. With over 25 ongoing clinical trials on intravitreal biologic therapy for AMD, enthusiasm for vanguard biologic therapies should be tempered by judicious monitoring for adverse events.

CONCLUSION

The importance of the CATT trial encompasses day-to-day treatment decisions for AMD, as well as lessons on how biologics for ocular disease should be implemented into clinical practice. Specifically, the introduction of intravitreal biologic therapies into clinical practice for uveitis, AMD, and other ocular diseases in which inflammation is involved should be guided by a clear understanding of the immunotherapeutic agent and its molecular target and with rigorous monitoring for both patient benefit and patient safety.

Bevacizumab for neovascular age-related macular degeneration in China

OBJECTIVE

To evaluate 2 different dosing regimens of intravitreal bevacizumab for the treatment of neovascular age-related macular degeneration (AMD) patients in China.

DESIGN

Multicenter, randomized, prospective, open-label clinical trial.

PARTICIPANTS

One hundred eighty-five patients with active neovascular AMD, exclusion of a macular scar, choroidal neovascularization not resulting from AMD, and polypoidal choroidal vasculopathy.

INTERVENTION

Patients were assigned randomly to receive intravitreal injections of bevacizumab every 6 weeks for the first 3 injections followed by injections every 6 weeks (regimen A, n = 91) or every 12 weeks (regimen B, n = 94).

MAIN OUTCOME MEASURES

The primary outcome measure was a comparison of the mean change in visual acuity from baseline. The secondary outcome measure was a comparison of the proportion of patients with a change in visual acuity of 15 letters or more. Adverse events were monitored.

RESULTS

One-hundred eighty five patients were enrolled. At 48 weeks, the increase in the mean visual acuity measurements from baseline were 12.58 letters in regimen A and 10.06 letters in regimen B (P = 0.288). At 48 weeks, the percentage of eyes losing fewer than 15 letters was 96.2% in regimen A and 93.9% in regimen B (P = 0.720). At 48 weeks, the median decrease in central retinal thickness measurements from baseline was 119 μm in regimen A and 60 μm in regimen B (P = 0.221). Adverse events during the 48 weeks included anterior chamber inflammation in 17 patients (18.7%) from regimen A and 9 patients (9.6%) from regimen B (P = 0.075). There were no other notable ocular adverse events in either group.

CONCLUSIONS

Intravitreal bevacizumab improved visual acuity and decreased macular thickness in patients with neovascular AMD when dosed either every 6 weeks or every 12 weeks after 3 doses given at 6-week intervals. Although there were no statistically significant differences between the 2 regimens, the results tended to favor the group dosed every 6 weeks (regimen A).