Off-label use of bevacizumab for the treatment of age-related macular degeneration: what is the evidence?

Mechanistic Insight into Age-Related Macular Degeneration (AMD): Anatomy, Epidemiology, Genetics, Pathogenesis, Prevention, Implications, and Treatment Strategies to Pace AMD Management

One of the most complicated eye disorders is age-related macular degeneration (AMD) which is the leading cause of irremediable blindness all over the world in the elderly. AMD is classified as early stage to late stage (advanced AMD), in which this stage is divided into the exudative or neovascular form (wet AMD) and the nonexudative or atrophic form (dry AMD). Clinically, AMD primarily influences the central area of retina known as the macula. Importantly, the wet form is generally associated with more severe vision loss. AMD has a systemic component, where many factors, like aging, genetic, environment, autoimmune and non-autoimmune disorders are associated with this disease. Additionally, healthy lifestyles, regular exercise, maintaining a normal lipid profile and weight are crucial to decreasing the risk of AMD. Furthermore, therapeutic strategies for limiting AMD should encompass a variety of factors to avoid and improve drug interventions, and also need to take into account personalized genetic information. In conclusion, with the development of technology and research progress, visual impairment and legal blindness from AMD have been substantially reduced in incidence. This review article is focused on identifying and developing the knowledge about the association between genetics, and etiology with AMD. We hope that this review will encourage researchers and lecturers, open new discussions, and contribute to a better understanding of AMD that improves patients' visual acuity, and upgrades the quality of life of AMD patients.

The First WHO International Standard for Harmonizing the Biological Activity of Bevacizumab

Several Bevacizumab products are approved for clinical use, with many others in late-stage clinical development worldwide. To aid the harmonization of potency assessment across different Bevacizumab products, the first World Health Organization (WHO) International Standard (IS) for Bevacizumab has been developed. Two preparations of a Bevacizumab candidate and comparator were assessed for their ability to neutralize and bind vascular endothelial growth factor (VEGF) using different bioassays and binding assays in an international collaborative study. Relative potency estimates were similar across different assays for the comparator or the duplicate-coded candidate sample. Variability in relative potency estimates was reduced when the candidate standard was used for calculation compared with various in-house reference standards, enabling harmonization in bioactivity evaluations. The results demonstrated that the candidate standard is suitable to serve as an IS for Bevacizumab, with assigned unitages for VEGF neutralization and VEGF binding activity. This standard coded 18/210 was established by the WHO Expert Committee on Biological Standardization, which is intended to support the calibration of secondary standards for product development and lifecycle management. The availability of IS 18/210 will help facilitate the global harmonization of potency evaluation to ensure patient access to Bevacizumab products with consistent safety, quality and efficacy.

Appraising the Quality of Systematic Reviews for Age-Related Macular Degeneration Interventions: A Systematic Review

Importance

Age-related macular degeneration (AMD) is a leading cause of vision impairment. It is imperative that AMD care is timely, appropriate, and evidence-based. It is thus essential that AMD systematic reviews are robust; however, little is known about the quality of this literature.

Objectives

To investigate the methodological quality of systematic reviews of AMD intervention studies, and to evaluate their use for guiding evidence-based care.

Evidence Review

This systematic review adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. All studies that self-identified as a systematic review in their title or abstract or were categorized as a systematic review from a medical subject heading and investigated the safety, efficacy and/or effectiveness of an AMD intervention were included. Comprehensive electronic searches were performed in Ovid MEDLINE, Embase, and the Cochrane Library from inception to March 2017. Two reviewers independently assessed titles and abstracts, then full-texts for eligibility. Quality was assessed using the Assessing the Methodological Quality of Systematic Reviews (AMSTAR) tool. Study characteristics (publication year, type of intervention, journal, citation rate, and funding source) were extracted.

Findings

Of 983 citations retrieved, 71 studies (7.6%) were deemed eligible. The first systematic review relating to an AMD intervention was published in 2003. More than half were published since 2014. Methodological quality was highly variable. The mean (SD) AMSTAR score was 5.8 (3.2) of 11.0, with no significant improvement over time (r = -0.03; 95% CI, -0.26 to 0.21; P = .83). Cochrane systematic reviews were overall of higher quality than reviews in other journals (mean [SD] AMSTAR score, 9.9 [1.2], n = 15 vs 4.7 [2.2], n = 56; P < .001). Overall, there was poor adherence to referring to an a priori design (22 articles [31%]) and reporting conflicts of interest in both the review and included studies (16 articles [23%]). Reviews funded by government grants and/or institutions were generally of higher quality than industry-sponsored reviews or where the funding source was not reported.

Conclusions and Relevance

There are gaps in the conduct of systematic reviews in the field of AMD. Enhanced endorsement of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement by refereed journals may improve review quality and improve the dissemination of reliable evidence relating to AMD interventions to clinicians.

The methodological quality of systematic reviews comparing intravitreal bevacizumab and alternates for neovascular age related macular degeneration: A systematic review of reviews

OBJECTIVE

To systematically collate and evaluate the evidence from recent SRs of bevacizumab for neo-vascular age related macular degeneration.

MATERIALS AND METHODS

Literature searches were carried out in Medline, Embase, Cochrane databases for all systematic reviews (SRs) on the effectiveness of bevacizumab for neo-vascular age related macular degeneration, published between 2000 and 2013. Titles and abstracts were assessed against the inclusion/exclusion criteria using Joanna Briggs Institute (JBI) study eligibility form. Data was extracted using the JBI data extraction form. The quality of the SRs was assessed using JBI critical appraisal checklist for SRs. Decisions on study eligibility and quality were made by two reviewers; any disagreements were resolved by discussion.

RESULTS

Nine relevant reviews were identified from 30 citations, of which 5 reviews fulfilled the review's inclusion criteria. All 5 reviews showed bevacizumab to be effective for neovascular AMD in the short-term when used alone or in combination with PDT or Pegaptanib. The average quality score of the reviews was 7; 95% confidence interval 6.2 to 7.8 (maximum possible quality score is 10). The selection and publication bias were not addressed in all included reviews. Three-fifth of the reviews had a quality score of 7 or lower, these reviews had some methodological limitations, search strategies were only identified in 2 (40%) reviews, independent study selection and quality assessment of included studies (4 (80%)) were infrequently performed.

CONCLUSION

Overall, the reviews on the effectiveness of intravitreal/systemic bevacizumab for neovascular  age-related macular generation (AMD) received good JBI quality scores (mean score = 7.0 points), with a few exceptions. The study also highlights the suboptimal reporting of SRs on this topic. Reviews with poor methodology may limit the validity of the reported results; hence efforts should be made to improve the design, reporting and publication of SRs across all journals.

Batch-to-batch N-glycosylation study of infliximab, trastuzumab and bevacizumab, and stability study of bevacizumab

Objectives

Infliximab, trastuzumab and bevacizumab are among the most frequently prescribed therapeutic proteins, and like most other therapeutic proteins, are glycosylated. As differences in glycosylation may significantly change the safety and efficacy of therapeutic glycoproteins, it is extremely important to control N-glycosylation consistency. In the first part of this study, the batch-to-batch consistency of the N-glycosylation of infliximab, trastuzumab and bevacizumab was analysed. In the second part, the consistency of the N-glycosylation of bevacizumab stored in polycarbonate syringes (for off-label drug use) for 3 months was examined.

Methods

N-glycans were (i) enzymatically released using peptide-N-glycosidase F, (ii) reduced, and (iii) analysed using hydrophilic interaction liquid chromatography coupled with high-resolution mass spectrometry. Mass spectrometry data were interpreted using principal component analysis combined with two-way analysis of variance and Tukey post hoc tests. The biological activity of infliximab and trastuzumab was examined using enzyme-linked immunosorbent assays.

Results

The results of both studies make important contributions to the field of hospital pharmacy. All batches of the studied therapeutic glycoproteins (infliximab, trastuzumab and bevacizumab) varied considerably (especially in galactosylation), while the N-glycosylation of bevacizumab remained unchanged during 3-month storage.

Conclusions

Threshold values for batch-to-batch N-glycosylation variations should be established and batch-to-batch glycosylation consistency should be regularly tested. In our study, samples with significantly different N-glycosylation profiles showed no significant variations in biological activity, suggesting that the differences are probably not therapeutically significant.

Interventions for Age-Related Macular Degeneration: Are Practice Guidelines Based on Systematic Reviews?

PURPOSE

Are existing systematic reviews of interventions for age-related macular degeneration incorporated into clinical practice guidelines?

DESIGN

High-quality systematic reviews should be used to underpin evidence-based clinical practice guidelines and clinical care. We examined the reliability of systematic reviews of interventions for age-related macular degeneration (AMD) and described the main findings of reliable reviews in relation to clinical practice guidelines.

METHODS

Eligible publications were systematic reviews of the effectiveness of treatment interventions for AMD. We searched a database of systematic reviews in eyes and vision without language or date restrictions; the database was up to date as of May 6, 2014. Two authors independently screened records for eligibility and abstracted and assessed the characteristics and methods of each review. We classified reviews as reliable when they reported eligibility criteria, comprehensive searches, methodologic quality of included studies, appropriate statistical methods for meta-analysis, and conclusions based on results. We mapped treatment recommendations from the American Academy of Ophthalmology (AAO) Preferred Practice Patterns (PPPs) for AMD to systematic reviews and citations of reliable systematic reviews to support each treatment recommendation.

RESULTS

Of 1570 systematic reviews in our database, 47 met inclusion criteria; most targeted neovascular AMD and investigated anti-vascular endothelial growth factor (VEGF) interventions, dietary supplements, or photodynamic therapy. We classified 33 (70%) reviews as reliable. The quality of reporting varied, with criteria for reliable reporting met more often by Cochrane reviews and reviews whose authors disclosed conflicts of interest. Anti-VEGF agents and photodynamic therapy were the only interventions identified as effective by reliable reviews. Of 35 treatment recommendations extracted from the PPPs, 15 could have been supported with reliable systematic reviews; however, only 1 recommendation cited a reliable intervention systematic review. No reliable systematic review was identified for 20 treatment recommendations, highlighting areas of evidence gaps.

CONCLUSIONS

For AMD, reliable systematic reviews exist for many treatment recommendations in the AAO PPPs and should be cited to support these recommendations. We also identified areas where no high-level evidence exists. Mapping clinical practice guidelines to existing systematic reviews is one way to highlight areas where evidence generation or evidence synthesis is either available or needed.

Ranibizumab: a review of its use in the treatment of neovascular age-related macular degeneration

Ranibizumab (Lucentis(®)), an inhibitor of all vascular endothelial growth factor (VEGF) A isoforms, is approved for the intravitreal treatment of neovascular age-related macular degeneration (AMD). In pivotal trials, monthly injections of ranibizumab were superior to verteporfin photodynamic therapy in the treatment of predominantly classic choroidal neovascularization (CNV) due to neovascular AMD (ANCHOR) and sham in the treatment of minimally classic or occult CNV due to neovascular AMD (MARINA). Monthly or less frequent injections of ranibizumab are generally well tolerated and associated with low rates of ocular and systemic serious adverse events (SAEs). Less frequent dosing has been evaluated with the aim of reducing the burden, risk and cost of monthly injections. In the landmark CATT trial, monthly monitoring and retreatment as-needed with ranibizumab was equivalent to monthly treatment in terms of the vision gain at 1 year, but reduced the number of injections (and the related cost) by approximately one-half. In head-to-head comparisons, aflibercept administered bimonthly was noninferior to ranibizumab administered monthly (VIEW 1 and 2), bevacizumab administered monthly was equivalent to ranibizumab administered monthly (CATT), and bevacizumab administered as-needed was equivalent to ranibizumab administered as-needed (CATT). Bevacizumab is widely used (off-label) for economic reasons; while it was less costly than ranibizumab, it was associated with more systemic SAEs. Notwithstanding the availability of other similarly effective anti-VEGF therapies that are approved (aflibercept) or unapproved (bevacizumab), ranibizumab continues to set the standard as regards the totality of evidence from randomized clinical trials demonstrating its efficacy and tolerability (particularly that of the monthly regimen) in the treatment of neovascular AMD.

Binding and neutralization of vascular endothelial growth factor (VEGF) and related ligands by VEGF Trap, ranibizumab and bevacizumab

Pharmacological inhibition of VEGF-A has proven to be effective in inhibiting angiogenesis and vascular leak associated with cancers and various eye diseases. However, little information is currently available on the binding kinetics and relative biological activity of various VEGF inhibitors. Therefore, we have evaluated the binding kinetics of two anti-VEGF antibodies, ranibizumab and bevacizumab, and VEGF Trap (also known as aflibercept), a novel type of soluble decoy receptor, with substantially higher affinity than conventional soluble VEGF receptors. VEGF Trap bound to all isoforms of human VEGF-A tested with subpicomolar affinity. Ranibizumab and bevacizumab also bound human VEGF-A, but with markedly lower affinity. The association rate for VEGF Trap binding to VEGF-A was orders of magnitude faster than that measured for bevacizumab and ranibizumab. Similarly, in cell-based bioassays, VEGF Trap inhibited the activation of VEGFR1 and VEGFR2, as well as VEGF-A induced calcium mobilization and migration in human endothelial cells more potently than ranibizumab or bevacizumab. Only VEGF Trap bound human PlGF and VEGF-B, and inhibited VEGFR1 activation and HUVEC migration induced by PlGF. These data differentiate VEGF Trap from ranibizumab and bevacizumab in terms of its markedly higher affinity for VEGF-A, as well as its ability to bind VEGF-B and PlGF.

The effect of nicotine on anti-vascular endothelial growth factor therapy in a mouse model of neovascular age-related macular degeneration

PURPOSE

The purpose of this article is to evaluate the effect of nicotine on anti-vascular endothelial growth factor therapy in the treatment of neovascular age-related macular degeneration.

METHODS

One group of mice received nicotine in drinking water and the other group received water only. Choroidal neovascularization (CNV) was induced with a laser. Nicotinic acetylcholine receptor-α7 (nAChRα7) expression was evaluated by immunohistochemistry. Bevacizumab or adiponectin peptide II (APNpII) was injected intravitreally on Day 7 postlaser, and the effects were evaluated on Days 14 and 21. α-Bungarotoxin was injected intraperitoneally on Days 2 to 5, and its effect was evaluated on Day 14.

RESULTS

Expression of nAChRα7 was 2 to 7 times higher between Days 3 and 7 postlaser compared with naive mice. In water-fed mice, APNpII, bevacizumab, and α-bungarotoxin significantly reduced CNV size. In nicotine-fed mice, treatment with APNpII or bevacizumab did not significantly reduce CNV size, whereas α-bungarotoxin did have an effect. Comparing water- and nicotine-fed mice, CNV size was 61% to 86% smaller in water-fed mice except for the α-bungarotoxin group, where there was no difference. Platelet-derived growth factor and vascular endothelial growth factor expression was 1.5- to 2.5-fold higher at Day 14 in nicotine-treated mice.

CONCLUSION

Nicotine significantly blocks the effect of anti-vascular endothelial growth factor therapy in the treatment of laser-induced neovascular age-related macular degeneration. nAChRα7 is significantly upregulated during the formation of CNV, and treatment with an nAChRα7 antagonist decreases CNV size irrespective of nicotine administration.

Canadian expert consensus: optimal treatment of neovascular age-related macular degeneration

BACKGROUND

New therapeutic approaches, particularly anti-vascular endothelial growth factor (anti-VEGF) therapies, prevent, and in some cases reverse, vision damage caused by age-related macular degeneration (AMD). Unequal access to care across Canada remains a problem for many retina specialists and their patients.

OBJECTIVE

To develop a consensus concerning the management of patients with exudative age-related macular degeneration (AMD).

DESIGN

Consensus document.

PARTICIPANTS

Ten Canadian retina specialists.

METHODS

The development of a consensus among Canadian experts concerning optimal treatment of AMD began with a review of the clinical evidence, daily practices, existing guidelines, and current national and international approvals and policies. The experts met on June 29, 2010, in Quebec City to discuss their findings and to propose strategies for consensus.

RESULTS

The result of this expert panel is a consensus proposal for Canadian ophthalmologists and retina specialists who are treating patients with or at risk for developing neovascular AMD.

CONCLUSIONS

The consensus provides guidelines to aid retina specialists in managing exudative AMD. Currently, ranibizumab is the only agent with sufficient Level I evidence and a Health Canada-approved indication for the treatment of wet AMD. Bevacizumab has been shown to be noninferior in preserving and improving visual acuity when compared to ranibizumab. Potential safety differences between the 2 drugs remain to be elucidated. The positioning of ranibizumab in this therapeutic area will be further defined as additional data for existing and emerging therapies become available. Until then, this agent remains the therapy of choice for individuals with neovascular AMD.

Therapeutic efficacy of bevacizumab for age-related macular degeneration: what are the implications of CATT for routine management?

CATT (Comparison of Age-related macular degeneration [AMD] Treatment Trials) examined the efficacy of ranibizumab and bevacizumab for the treatment of neovascular AMD. This prospective, randomized, but unblinded trial revealed a significant improvement in vision with both treatments in terms of visual acuity; importantly, patients with juxtafoveal choroidal neovascularization (CNV) and retinal pigment epithelial detachments were not excluded from the study. Monthly treatment with the drugs resulted in similar increases in visual acuity, although angiograms indicated that ranibizumab was superior in terms of reducing retinal fluid and leakage. As the study also differentiated between a fixed regimen and an as-needed (pro re nata [PRN]) dosing regimen, a larger sample size and Bonferroni statistical correction were necessary. The equivalence of the PRN dosing of bevacizumab to the monthly treatment could not be confirmed. Almost all of the frequent deviations from the protocol (referring to retreatment criteria: 25.7-28.5%) resulted in under-treatment. Since this applied to both drugs equally, under-treatment alone could not explain the larger loss of visual acuity observed in the bevacizumab PRN arm. The PRN regimen was generally associated with a larger lesion size after 12 months compared with the fixed treatment regimens. The investigators accepted the drawbacks of an incomplete masking to allow co-payment by Medicare. As assessments of drug trials are often politically motivated, the higher demands of a non-inferiority trial compared with a superiority design must be emphasized. A comparison of the per-protocol and last-observation-carried-forward analysis has not yet been published; ongoing subgroup analysis might highlight the impact of different lesion characteristics. While CATT provided further evidence for the efficacy of bevacizumab treatment, differences in adverse events between the two treatments (e.g. a higher rate of serious adverse events with bevacizumab compared with ranibizumab) were reported; however, these still have to be analysed, with the larger sample sizes of previous ranibizumab studies needing to be taken into account. Preclinical studies imply some differences between the drugs in terms of their adverse event profiles. A possible increased risk of adverse events could not be ruled out by previous clinical case series and CATT because the sample sizes and the follow-up intervals were not adequate. The large discrepancy in the price of bevacizumab versus ranibizumab in the US means a cost-benefit analysis is warranted. A lack of quality-of-life data has prevented calculation of an appropriate bevacizumab price in the context of its performance in the ophthalmological setting. Thus, CATT suggests that a favourable visual acuity might be achieved by very frequent administration of bevacizumab in patients with neovascular AMD. Although there are certain safety caveats, increased focus on subgroup analyses and obtaining longer follow-up data are expected to yield additional information of clinical relevance.

Pharmacotherapy for neovascular age-related macular degeneration: an analysis of the 100% 2008 medicare fee-for-service part B claims file

PURPOSE

To describe the usage patterns of pharmacological treatments for neovascular age-related macular degeneration (AMD) in Medicare fee-for-service beneficiaries.

DESIGN

Retrospective review of all Medicare fee-for-service Part B claims for neovascular AMD during 2008.

METHODS

Medicare beneficiaries having undergone treatment were identified. The data collected for each visit for a given beneficiary included age, race, gender, Medicare region, state/zip code of residence, date of visit, whether or not the beneficiary had a treatment, the type and amount of drug, and dollars paid by Medicare. The main outcome measures were the number and rate of treatments, the types of drugs used for treatment, and the payments for these drugs.

RESULTS

Of the 222 886 unique beneficiaries, 146 276 (64.4%) received bevacizumab and 80 929 (35.6%) received ranibizumab. A total of 824 525 injections were performed with 480 025 injections of bevacizumab (58%) and 336 898 injections of ranibizumab (41%). National rates of injections per 100 000 fee-for-service Part B Medicare beneficiaries for bevacizumab and ranibizumab were 1506 and 1057, respectively. Total payments by Medicare were $20 290 952 for bevacizumab and $536 642 693 for ranibizumab. In 39 out of 50 states, the rate of injection was higher for bevacizumab compared with ranibizumab.

CONCLUSIONS

In 2008, bevacizumab was used at a higher rate than ranibizumab for the treatment of neovascular AMD. Even though bevacizumab accounted for 58% of all injections, Medicare paid $516 million more for ranibizumab than bevacizumab. These data suggest that despite its off-label designation, intravitreal bevacizumab is currently the standard-of-care treatment for neovascular AMD in the United States.