Frühe Effekte nach systemischer und intravitrealer Bevacizumab (Avastin®)-Therapie bei neovaskulärer altersbedingter Makuladegeneration

Potential antiedematous effects of intravitreous anti-VEGF, unrelated to VEGF neutralization

The intravitreous injection of therapeutic proteins that neutralize vascular endothelial growth factor (VEGF) family members is efficient to reduce macular edema associated with wet age-related macular degeneration (AMD), retinal vein occlusion (RVO) and diabetic retinopathy (DR). It has revolutionized the visual prognosis of patients with macular edema. The antiedematous effect is dependent on an intravitreous dose of drug, which varies between patients and requires frequent and repeated injections to maintain its effects. At the time when optimizing the duration of anti-VEGF effects is a major challenge, understanding how anti-VEGF reduces macular edema is crucial. We discuss herein how anti-VEGF exerts antiedematous effects and raise the hypothesis that mechanisms, unrelated to VEGF neutralization, might have been underestimated.

Intravitreal bevacizumab (Avastin) vs. ranibizumab (Lucentis) for the treatment of age-related macular degeneration: a systematic review

PURPOSE OF REVIEW

We conducted a systematic review to evaluate whether the existing evidence justifies the intravitreal use of bevacizumab in comparison to ranibizumab in age-related macular degeneration.

RECENT FINDINGS

Compared with photodynamic therapy, bevacizumab shows a relative improvement in visual acuity that is of similar size as in the comparison of ranibizumab with photodynamic therapy (relative improvement from 30 to 35%). However, this finding is based on one randomized controlled trial including less than 50 patients treated with bevacizumab. Also, nothing is known about long-term (>12 months) improvements in visual acuity and optimal treatment intervals for bevacizumab.Regarding safety, the published literature indicates that ocular and systemic adverse effects are less frequent under bevacizumab than ranibizumab treatment. But the validity of this finding is strongly limited by inadequate reporting, an unsystematic evaluation of adverse effects and short follow-up times in studies evaluating bevacizumab.

SUMMARY

Given the lack of controlled data, the widespread off-label use of bevacizumab is not justified in clinical practice. On the other hand, a major challenge in the management of patients who require repeated antivascular endothelial growth factor injections is the high cost of ranibizumab. This dilemma underlines the need for head-to-head studies comparing both vascular endothelial growth factor antibodies, or, at least, well conducted randomized controlled trials evaluating intravitreal bevacizumab.

Clinical and histological findings after intravitreal injection of bevacizumab (Avastin) in a porcine model of choroidal neovascularization

PURPOSE

To examine the effect of intravitreally injected bevacizumab (Avastin) on the histological and angiographic morphology of choroidal neovascularization (CNV) in a masked and placebo-controlled animal study.

METHODS

Choroidal neovascularization was induced surgically in 11 porcine eyes by perforating Bruch's membrane with a retinal perforator. After closure of the ports used for the vitrectomy, which was performed to facilitate the Bruch's membrane rupture, 0.05 ml of either bevacizumab or Ringer-Lactat (placebo) was injected into the vitreous cavity. Eyes were enucleated after 14 days. Fundus photographs and fluorescein angiograms (FAs) were obtained immediately prior to enucleation. Sections of formalin- and paraffin-embedded eyes were examined by light microscopy and by immunohistochemical staining.

RESULTS

Placebo-injected eyes exhibited the highest propensity to leak, with five of six eyes leaking on FA, whereas only one of five bevacizumab-injected eyes exhibited leakage. On histological examination, all 11 eyes contained CNV membranes of similar size, regardless of treatment. The number of vascular endothelial cells was significantly reduced (p = 0.03) in CNV membranes from eyes that had been injected with bevacizumab when compared with CNV membranes from placebo-injected eyes. There was a trend towards more retinal pigment epithelium cells (p = 0.16) and fewer glial fibres (p = 0.08) in membranes from bevacizumab-treated eyes compared with placebo-treated eyes. Bevacizumab was identified immunohistochemically in the inner limiting membrane (ILM) and to a lesser degree in the remaining retina. Strong staining was also detected in both retinal blood vessels and entire CNV membranes with no cellular predisposition. Vascular endothelial growth factor expression was found in the CNV membranes, in the ILM, in the ganglion cell layer, in Müller cells throughout the neuroretina and in retinal blood vessels.

CONCLUSIONS

Bevacizumab significantly reduced the proliferation of vascular endothelial cells in CNV membranes and showed a strong trend towards a reduction of leakage from these membranes. After a single injection, bevacizumab did not exhibit a size reducing effect on CNV, but it was still present in the membranes 14 days after intravitreal injection.

Intravitreal bevacizumab (Avastin) for age-related macular degeneration: a critical analysis of literature

PURPOSE

The current medical environment demands that quality health care is delivered at an affordable cost through the use of objective, unbiased clinical data. This study was undertaken to review the current literature on bevacizumab for age-related macular degeneration and its value in determining best clinical practice.

METHODS

Randomised controlled trials (RCTs) and observational studies that met the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) criteria were identified from the current literature for further analysis. Data concerning treatment dosing regimens, response to treatment, complications, and factors influencing outcome and safety were extracted and compiled into a database.

RESULTS

As of January 2009, there were 5 RCTs that compared the outcomes of bevacizumab to other treatment options and 50 studies that met the STROBE criteria with similar visual and anatomical outcomes between RCTs and observational studies. Although the doses and dosing frequencies varied between the studies, the mean gain in vision at 3 months was +7.76+/-5.4 ETDRS letters (range +2 to +14.4); an effect that was maintained at 6 months in studies with longer follow-up. Predominantly classic lesions were the most responsive of all lesion subtypes. The complication profiles/rates were similar to those reported with other anti-vascular endothelial agents.

CONCLUSIONS

There is sufficient scientific and statistical evidence to advocate the effective use of OCT-guided administration of intravitreal bevacizumab for neovascular AMD. This is reflected in our study outcome measures that are comparable to findings published from recent well-conducted RCTs on intravitreal ranibizumab at the same time point.

Antivascular endothelial growth factor therapy for neovascular age-related macular degeneration

PURPOSE OF REVIEW

The most important recent advance in the treatment of neovascular age-related macular degeneration (AMD) is the development of antivascular endothelial growth factor (anti-VEGF) therapeutic agents that preserve and improve visual acuity by arresting choroidal neovascular growth and reducing vascular permeability. This review describes the current literature on the use of this therapeutic approach in the management of neovascular AMD.

RECENT FINDINGS

Two anti-VEGF agents, pegaptanib sodium and ranibizumab, are currently approved by the United States Food and Drug Administration for the treatment of neovascular AMD. In addition, off-label use of a third anti-VEGF agent, bevacizumab, as a treatment option for neovascular AMD has become common worldwide. Other anti-VEGF agent strategies that have shown efficacy include small interfering RNA agents to silence the VEGF gene and receptor and the fusion protein VEGF trap.

SUMMARY

The accumulation of preclinical and clinical evidence implicating VEGF-A in the pathogenesis of neovascular AMD has provided a strong rationale for the development of anti-VEGF agents for this disease. Anti-VEGF therapies have been used successfully in the clinic, encouraging their use in the treatment of other neovascular eye diseases.

Intravitreal bevacizumab (Avastin) injection for neovascular glaucoma: a survey on 23 cases throughout 12-month follow-up

AIMS

Neovascular glaucoma (NVG) represents one of the most severe forms of secondary glaucoma, caused by a number of ocular and systemic conditions, which share the common element of retinal ischaemia/hypoxia that initiates the subsequent release of angiogenesis factors, with consequent development of new abnormal vessels through the ciliary body. The aim was to examine the potential efficacy and safety of intravitreal injection of bevacizumab (IVB) (Avastin) in the treatment of NVG in patients who had already undergone the standard retinal ablative procedure.

METHODS

This was a prospective pilot trial. Clinical data of 26 eyes from 23 patients, including diagnosis, visual acuity, iris fluorescein angiography stage and intraocular pressure (IOP), were collected. Three injections of bevacizumab were scheduled for each recruited eye at 4-week intervals from the start. All investigations were repeated the day before the IVB (1.25 mg/0.05 ml) and at the 1-, 3-, 6-, 9- and 12-month follow-up.

RESULTS

Regression of corneal oedema together with significant pain reduction was achieved in all eyes already after the first IVB, without any noteworthy improvement of visual acuity. At the end of the scheduled protocol (three IVB), regression of iris neovascularization was documented in all patients, together with significant improvement of visual acuity. The IOP reduction from baseline ranged from 30 to 0 mmHg (12.1 +/- 8 mmHg).

CONCLUSIONS

Intravitreal bevacizumab, as adjunctive treatment to the standard retinal ablative procedure, seems promising for the management of conditions responsible of retinal ischaemia/hypoxia associated with NVG.

Clinical and histological aspects of CNV formation: studies in an animal model

The purpose of the present thesis was to develop an animal model of CNV in order to study the early formation of CNV and to test the effects of an anti-angiogenic treatment. Porcine eyes were chosen as a substrate for CNV induction, since they are similar to human eyes in terms of both macroscopic and microscopic morphology. However, a major difference is that pigs lack a fovea; instead they have a visual streak, with a relatively stable and high concentration of cones. By surgical perforation of Bruch's membrane we were able to induce formation of CNV membranes. The morphology and cellular composition of these membranes varied with the surgical technique employed. When RPE cells were locally removed at the time of perforation, the resulting CNV was thinner, contained fewer blood vessels and was less prone to leak on fluorescein angiography than when RPE cells were left intact at induction. The neuroretina overlying the perforation site was not damaged by any of the surgical techniques, thus allowing the subsequent retinal damage to be ascribed to the actual process of CNV formation. Using this animal model allowed us to directly map histological findings onto fluorescein angiograms and thereby perform meaningful correlations between histopathologic and photographic features. Such correlations have been hampered in human subjects, since human eyes are not enucleated as a consequence of CNV and are therefore only available for post-mortem studies. In such studies there often is a considerable time-gap between the death of the patient and the latest available fluorescein angiogram, thereby allowing macular pathology to evolve in the interim. Histological examination of the porcine membranes demonstrated that they were composed of RPE cells, glial cells, macrophages, endothelial cells, collagen and smooth muscle fibres, which are the same cellular and fibrillar elements that dominate human CNV membranes. The porcine model was applied to test the effects, in a randomized and masked fashion, of intravitreally injected bevacizumab. Bevacizumab, a pan VEGF A antibody, was found to reduce both the proliferation of endothelial cells in CNV membranes and the propensity to leak in fluorescein angiograms. Immunohistochemically, bevacizumab was detected in the inner limiting membrane, in retinal blood vessels and binding uniformly to the entire CNV membrane without any cellular predisposition. Based on the above findings we believe that the porcine CNV model shows a bearing to human disease and therefore might be used as a tool to obtain improved treatments for this debilitating condition.

Intravitreales Bevacizumab vs. Verteporfin und intravitreales Triamcinolon Acetonid bei Patienten mit neovaskulärer AMD

AIM

The aim of this study was to compare intravitreal bevacizumab (IVB) and verteporfin therapy in combination with 4 mg intravitreal triamcinolone (PDT-IVTA) in patients with neovascular age-related macular degeneration (AMD).

PATIENTS AND METHODS

A total of 30 eyes of 30 patients with neovascular AMD were included in a prospective, randomized study. Ten eyes received PDT-IVTA with a standard light fluence of 50 J/cm(2) (SPDT-IVTA), ten were treated with PDT-IVTA with a reduced light fluence of 25 J/cm(2) (RPDT-IVTA) and ten received IVB. The main outcome was evaluated using early treatment diabetic retinopathy study (ETDRS) visual acuity, fluorescein angiography and optical coherence tomography (OCT) at baseline as well as at day 1, week 1, 1 month and 3 months after therapy.

RESULTS

At the beginning of therapy, the distribution of the groups was balanced. After 3 months, the SPDT-IVTA group showed a non-significant vision loss of seven letters (p<0.3) while a vision loss of 0.5 letters (p<0.9) was found in the RPDT-IVTA group. At the same time, the IVB group had a vision improvement of 11.8 letters (p<0.001). This vision improvement was statistically significant compared to the results of both PDT-IVTA groups (p<0.005). Central retinal thickness (CRT) decreased up to month 3 in the SPDT-IVTA group by 132 microm, in the RPDT-IVTA group by 78 mum and in the IVB group by 138 microm, (p<0.05 in the three groups). No significant difference in the decrease of CRT was found between the treatment groups after 3 months.

CONCLUSION

IVB shows significantly better results in vision improvement in the short-term compared to the two PDT-IVTA groups. Within 3 months, all groups showed a comparable decrease in CRT. Long-term follow-up is required to evaluate the safety and treatment efficacy of all treatment modalities.

[Inhibition of angiogenesis in the anterior chamber of the eye]

BACKGROUND

Recent years have seen tremendous progress in our understanding of the mechanisms of neovascular diseases of the eye. Antiangiogenic treatment options are now widely used in the management of age-related maculopathy (AMD) and diabetic retinopathy. The aim of this article is to highlight some novel methods of local antiangiogenic treatment of the cornea and conjunctiva and in the anterior chamber of the eye.

METHODS

The study took the form of a literature review (PUBMED) and a review of the authors' own data.

RESULTS

Initial experience with novel inhibitors of angiogenesis, especially bevacizumab, used locally on cornea and conjunctiva is promising. Intracameral injections of VEGF inhibitors can be used to ameliorate neovascular glaucoma.

CONCLUSION

Novel antiangiogenic drugs are available for topical use in the anterior segment of the eye (as off-label use) and will improve the management of neovascular diseases affecting cornea and conjunctiva and in the anterior chamber of the eye.

Bevacizumab zur Therapie des Makulaödems infolge venöser retinaler Gefäßverschlüsse

BACKGROUND

Retinal vein occlusion often leads to macular edema as a result of an elevated level of intravitreal VEGF. We report on the anatomic and functional results after intravitreal bevacizumab injections in patients with retinal vein occlusion.

METHODS

In a prospective study, 18 patients with central, and 22 patients with branch retinal vein occlusion, all of whom had persistent macular edema (>300 microm) received 2.5 mg intravitreal bevacizumab. ETDRS visual acuity, ophthalmic examination and stratus OCT were performed at baseline, 1 week after injection and then monthly. Further injections were given every 6 weeks in patients with persistent or recurring macular edema.

RESULTS

The findings did not deteriorate in any of the 40 patients. The injections (mean of 2.6+/-1.4 injections/patient) were very well tolerated in all cases during a mean follow-up of 23+/-13 weeks. On the last visit, 73.3% of patients with central retinal vein occlusion and 76.5% of those with branch retinal vein occlusion were found to have significantly improved visual acuity (by at least 3 lines). Mean central retinal thickness had decreased from 921+/-264 to 239+/-66.2 microm in patients with central retinal vein occlusion, and from 678+/-221 to 236+/-78 microm in patients with branch retinal vein occlusion.

CONCLUSIONS

Neither intraocular nor systemic side-effects were observed in this study after repeated intravitreal injections of 2.5 mg bevacizumab. Current results suggest that intravitreal anti-VEGF therapy is a promising option in macular edema secondary to retinal vein occlusion.