Treatment of macular degeneration - controversy and hope

A systematic review of the efficacy and safety outcomes of anti-VEGF agents used for treating neovascular age-related macular degeneration: comparison of ranibizumab and bevacizumab

OBJECTIVE

To systematically review ocular and systemic events in treatment of wet age-related macular degeneration (AMD) with anti-vascular endothelial growth factor antibodies, ranibizumab and bevacizumab, and to provide a detailed perspective of their differences on clinical use, efficacy and safety.

RESEARCH DESIGN AND METHODS

This review was based on a 2010 PubMed literature search performed using two separate terms: 'lucentis' OR 'ranibizumab' AND 'age-related macular degeneration' OR 'AMD' or 'avastin' OR 'bevacizumab' AND 'age-related macular degeneration' OR 'AMD'. A clinical diagnosis of wet AMD was defined by the authors of the trial reports. Clinical studies that met Level I or Level II evidence criteria were considered for review.

FINDINGS

Eight large, randomized, controlled trials of ranibizumab (Level I) included 1,485 patients (range 162-716) and four open-label studies of ranibizumab (Level II) included 4,484 patients (range 32-4,300). Six studies (one Level I, five Level II) of bevacizumab included 424 patients (range 28-165). All demonstrated improvements in visual acuity. Only one study (Level II) compared the efficacy of ranibizumab and bevacizumab. Adverse ocular and systemic safety events occurring during the study were prospectively recorded for ranibizumab, irrespective of their suspected relationship to study treatments. Only three of six bevacizumab studies reported details of adverse ocular or systemic events. There was extensive Level I and Level II evidence to support both the efficacy and safety of ranibizumab in wet AMD. Data suggest that bevacizumab provides efficacy in wet AMD, but the safety profile of intravitreal bevacizumab remains to be established.

CONCLUSION

In contrast to ranibizumab, current safety data for bevacizumab are incomplete and not yet robust. If the medical community remains committed to using intravitreal bevacizumab, it is critical to establish that it has an acceptable safety profile, supported by evidence-based medicine. Considerable further research is warranted to achieve this.

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

There is an active and controversial debate about the role of intravitreal bevacizumab versus approved drugs in the treatment of neovascular age-related macular degeneration (AMD). Because bevacizumab was available prior to the launch of ranibizumab, off-label use of the former became widespread and the cancer drug bevacizumab is the most commonly used medication in ophthalmology nowadays. This review considers every publication identified in MEDLINE using the keywords 'bevacizumab' and 'Avastin' between 1 June 2005 and 31 July 2008. The search identified 511 papers that were evaluated. In 33 studies, there was consistent and clear evidence for the efficacy of bevacizumab in neovascular AMD. However, the highest grade studies (three prospective, randomized, controlled trials) did not attain better than grade 2b level of evidence, and objective evaluation of the benefit of bevacizumab relative to representative controls was therefore not possible. Certainly, the available evidence is inferior to that obtained from the approval studies of ranibizumab and this should influence treatment selection and guidance of patients. These considerations indicate that important quality criteria need to be included in future studies to ensure more meaningful conclusions can be drawn. These include clearly defined inclusion criteria, information about the recruitment procedure (including data on withdrawals, excluded patients, concealed treatment allocation, use of intention-to-treat analyses and blinded assessment procedures). Although preclinical studies have almost exclusively found bevacizumab to be safe, the design utilized in clinical case series cannot rule out a possible increase in adverse events, which already show a high spontaneous incidence in elderly AMD patients. The superior evidence level for ranibizumab and the limited safety data for bevacizumab must be taken into consideration when evaluating the costs that a healthcare system is willing to spend. However, the superior grade of evidence for ranibizumab should not be confused with the (still missing) evidence for superior efficacy. The results of ongoing randomized, controlled, comparative trials will provide further data on the efficacy and cost effectiveness of bevacizumab and ranibizumab in the treatment of AMD. In the meantime, patients should be informed about the alternatives, the price differences and the restricted liability issue when off-label use of bevacizumab is offered.