Bevacizumab and Triamcinolone Acetonide for Choroidal Neovascularization Due to Age-Related Macular Degeneration Unresponsive to Antivascular Endothelial Growth Factors

Managing Neovascular Age-Related Macular Degeneration in Clinical Practice: Systematic Review, Meta-Analysis, and Meta-Regression

The use of anti-vascular endothelial growth factor (VEGF) agents has profoundly changed the prognosis of neovascular age-related macular degeneration (nAMD). As clinical experiences have accumulated, it has become mandatory to summarize data to give information that can be useful in everyday practice. We conducted a systematic review to identify randomized controlled trials (RCTs) and observational studies that reported 12-month changes in best-corrected visual acuity (BCVA) in patients with nAMD on anti-VEGF monotherapy. Data were analyzed in a random-effects meta-analysis with BCVA change as the primary outcome. Meta-regression was conducted to evaluate the impact of multiple covariates. Four hundred and twelve heterogeneous study populations (109,666 eyes) were included. Anti-VEGFs induced an overall improvement of +5.37 ETDRS letters at 12 months. Meta-regression showed that mean BCVA change was statistically greater for RCTs (p = 0.0032) in comparison with observational studies. Populations following a proactive regimen had better outcomes than those following a reactive treatment regimen. Mean BCVA change was greater in younger populations, with lower baseline BCVA and treated with a higher number of injections (p < 0.001). Our results confirm that anti-VEGFs may produce a significant functional improvement at 12 months in patients with nAMD.

Dexamethasone implant improves anatomic response to anti-VEGF therapy in treatment-resistant polypoidal choroidal vasculopathy

BACKGROUND

A significant proportion of eyes with polypoidal choroidal vasculopathy (PCV) can be resistant to anti-vascular endothelial growth factor (VEGF) injections. We evaluated the efficacy of a combination of dexamethasone intravitreal implant (DXI) and anti-VEGF therapy in eyes resistant to anti-VEGF monotherapy.

METHODS

In this retrospective study, patients with PCV resistant to anti-VEGF injections were additionally injected with a DXI along with an anti-VEGF agent. Best-corrected visual acuity (BCVA), slit-lamp examination, fundus evaluation, and optical coherence tomography (OCT) data were analyzed. Anatomical response on OCT was the primary outcome measure. Change in visual acuity and injection-free interval after DXI were evaluated as secondary outcome measures.

RESULTS

Twelve eyes of 11 patients were included in the study. Mean age of patients at presentation was 64.7 ± 9.5 years (range, 49-78.8 years), and there were seven females (63.6%). Median number of anti-VEGF injections prior to DXI was 4 (interquartile range IQR, 3-7). Median follow-up duration after DXI was 32.2 months (IQR, 6.6-41.6 months). Median logMAR BCVA immediately prior to DXI was 0.41 (IQR, 0.30-0.88) and after injection was 0.40 (IQR, 0.30-1.05), which was not significantly different (p = 0.85). Median Central Retinal Thickness (CRT) after DXI was 305.5 µm (IQR, 249-409 µm), which was significantly (p = 0.003) lesser than pre-injection thickness of 547 µm (IQR, 431-771 µm). Median injection-free interval in these eyes after DXI was 5 months (IQR, 2.8-6.4 months). Kaplan-Meier estimates of first injection after DXI were 27.3% at 3 months, 67.3% at 6 months, and 89.1% at 12 months.

CONCLUSIONS

Dexamethasone implant combined with anti-VEGF treatment can prolong the treatment-free interval in eyes with PCV resistant to anti-VEGF injection while maintaining visual acuity.

Systemic dendrimer nanotherapies for targeted suppression of choroidal inflammation and neovascularization in age-related macular degeneration

Inflammation and neovascularization are key pathological events in human age-related macular degeneration (AMD). Activated microglia/macrophages (mi/ma) and retinal pigmented epithelium (RPE) play an active role in every stage of disease progression. Systemic therapies that can target these cells and address both inflammation and neovascularization will broaden the impact of existing therapies and potentially open new avenues for early AMD where there are no viable therapies. Utilizing a clinically relevant rat model of AMD that mirrors many aspects that of human AMD pathological events, we show that systemic hydroxyl-terminated polyamidoamine dendrimer-triamcinolone acetonide conjugate (D-TA) is selectively taken up by the injured mi/ma and RPE (without the need for targeting ligands). D-TA suppresses choroidal neovascularization significantly (by >80%, >50-fold better than free drug), attenuates inflammation in the choroid and retina, by limiting macrophage infiltration in the pathological area, significantly suppressing pro-inflammatory cytokines and pro-angiogenic factors, with minimal side effects to healthy ocular tissue and other organs. In ex vivo studies on human postmortem diabetic eyes, the dendrimer is also taken up into choroidal macrophages. These results suggest that the systemic hydroxyl dendrimer-drugs can offer new avenues for therapies in treating early/dry AMD and late/neovascular AMD alone, or in combination with current anti-VEGF therapies. This hydroxyl dendrimer platform but conjugated to a different drug is undergoing clinical trials for severe COVID-19, potentially paving the way for faster clinical translation of similar compounds for ocular and retinal disorders.

Comparative study on pharmacokinetics and toxicity of intravitreal and sub-Tenon injection of triamcinolone acetonide in ocular tissues

AIM

To compare the differences in kinetics, distribution, and toxicity of triamcinolone acetonide (TA) between the injection methods, sub-Tenon and intravitreal injections in rabbit ocular tissues.

METHODS

TA was injected into the vitreous or the sub-Tenon in rabbits. For pharmacokinetic study, rabbits were sacrificed periodically and then TA in blood and ocular tissues (retina/choroids, vitreous, and aqueous humor) were measured over 91d. For toxicological study, clinical signs, slit-lamp microscopic examination, ophthalmological test were performed. The eyeballs and surrounding tissues were collected and fixed with glutaraldehyde-formalin solution, and then paraffin embedded for histological investigation.

RESULTS

Higher levels of TA were distributed in the intraocular tissues when injected into the vitreous compared to the sub-Tenon. Conversely, TA level was remarkably lower in the rabbits which received intravitreal TA injections than those treated with sub-Tenon injection throughout the study period in plasma. Optical discharge probably caused by systemic circulation of TA was observed by receiving sub-Tenon TA injection. Meanwhile, technic-associated toxicological ocular symptoms and findings were more frequently observed in intravitreal injection than in sub-Tenon injection.

CONCLUSION

There are significant differences in kinetics and distribution of TA in vitreous body, aqueous humor and plasma, between the two injection methods. Although further study is needed to explain the species difference between human and rabbit, it is assumed that the difference in the frequency of intraocular pressure elevation and cataract formation by TA between the two injection methods are directly related to the TA concentrations in aqueous humor and vitreous body in each injection methods. Systemic toxicity and technic-associated toxicity are also closely related to kinetics of TA in plasma and each injection method itself, respectively.

ROLE OF ADDITIONAL DEXAMETHASONE FOR THE MANAGEMENT OF PERSISTENT OR RECURRENT NEOVASCULAR AGE-RELATED MACULAR DEGENERATION UNDER RANIBIZUMAB TREATMENT

PURPOSE

To assess the efficacy of a combination therapy of intravitreal ranibizumab together with a dexamethasone implant in comparison with ranibizumab monotherapy in neovascular age-related macular degeneration.

METHODS

Forty eyes of recurrent or persistent neovascular age-related macular degeneration were included in this prospective study. Patients were randomly assigned to two groups. Based on a pro re nata treatment regimen, the first group received intravitreal ranibizumab monotherapy (IVM). The second group received a combination of intravitreal dexamethasone implant and ranibizumab (intravitreal combination [IVC]) at baseline and was retreated with ranibizumab as needed. A second dexamethasone implant was allowed for retreatment after at least 6 months. Retreatment criteria included evidence of subretinal fluid, cystoid macular edema or new hemorrhage, and/or a visual acuity decrease of 5 Early Treatment Diabetic Retinopathy Study letters.

RESULTS

During 12 months, a mean of 7.95/5.5 (IVM/IVC; P = 0.042) retreatments were given. The median time until first retreatment differed significantly between the groups (P = 0.004). Functional variables could be maintained in both groups with no differences between them. Visual acuity changed from 62 letters at baseline to 67 at Month 12 in the IVM and remained stable at 68 letters in the IVC group (P = 0.68); macular sensitivity changed from 6.95 dB to 7.01 dB in IVM and from 7.24 dB to 7.12 dB in IVC (P = 0.4). Central retinal thickness decreased, however, with no difference between the groups (P = 0.38). In the IVM/IVC group, 11/12 (55/60%) patients were phakic at the time of study entry. One (9%) patient from the IVM and 4 (33%) from the IVC group were referred to cataract surgery after study completion (P = 0.4).

CONCLUSION

This pilot study indicates combined therapy to delay retreatment in patients with persistent/recurrent neovascular age-related macular degeneration and an overall reduction in required ranibizumab retreatments compared with ranibizumab monotherapy with consistent functional outcomes.

Retinal and choroidal angiogenesis: a review of new targets

Retinal and choroidal neovascularization are a major cause of significant visual impairment, worldwide. Understanding the various factors involved in the accompanying physiopathology is vital for development of novel treatments, and most important, for preserving patient vision. The intraocular use of anti-vascular endothelial growth factor therapeutics has improved management of the retinal and choroidal neovascularization but some patients do not respond, suggesting other vascular mediators may also contribute to ocular angiogenesis. Several recent studies examined possible new targets for future anti-angiogenic therapies. Potential targets of retinal and choroidal neovascularization therapy include members of the platelet-derived growth factor family, vascular endothelial growth factor sub-family, epidermal growth factor family, fibroblast growth factor family, transforming growth factor-β superfamily (TGF-β1, activins, follistatin and bone morphogenetic proteins), angiopoietin-like family, galectins family, integrin superfamily, as well as pigment epithelium derived factor, hepatocyte growth factor, angiopoietins, endothelins, hypoxia-inducible factors, insulin-like growth factors, cytokines, matrix metalloproteinases and their inhibitors and glycosylation proteins. This review highlights current antiangiogenic therapies under development, and discusses future retinal and choroidal pro- and anti-angiogenic targets as wells as the importance of developing of new drugs.

Vision Preservation in Eyes of Polypoidal Choroidal Vasculopathy with Low-Dose Intravitreal Triamcinolone Acetonide

PURPOSE

To evaluate the efficacy and adverse effects of using low-dose intravitreal triamcinolone acetonide (IVTA) to preserve vision in polypoidal choroidal vasculopathy (PCV) eyes.

METHODS

This retrospective chart review study examined 8 eyes of 7 PCV patients, for whom verteporfin photodynamic therapy (vPDT) or antivascular endothelial growth factor (VEGF) therapy was not affordable/available and also with intolerable risk because of underlying cardiovascular and/or cerebrovascular ischemia. Low-dose IVTA (1 mg/0.025 mL) monotherapy was administered and repeated every 4 weeks if intraretinal edema or subretinal fluid persisted.

RESULTS

The median follow-up time was 26.4 months. Three eyes (3/8) maintained their initial best-corrected visual acuity and 4 eyes (4/8) exhibited improvement, whereas 1 eye (1/8) sustained some loss. The mean injection number per month was 0.7 for the first 6 months, after which it decreased to 0.4. In regard to adverse effects, intraocular pressure (IOP) of more than 21 mmHg was noted as persisting for a few weeks in 4 eyes and that of more than 30 mmHg was noted once in 1 eye. The increased IOP was adequately controlled by using IOP-lowering agents. Two initially phakic eyes each underwent cataract surgery in the 12th and 14th months after treatment.

CONCLUSIONS

Low-dose IVTA therapy may be valuable for preserving the vision of PCV patients, while vPDT or anti-VEGF is not affordable/available or of those with underlying diseases for whom anti-VEGF therapy is with intolerable risk.

INTRAVITREAL AFLIBERCEPT FOR CHOROIDAL NEOVASCULARIZATION DUE TO AGE-RELATED MACULAR DEGENERATION UNRESPONSIVE TO RANIBIZUMAB THERAPY

PURPOSE

To assess the efficacy of intravitreal injection of aflibercept for treating choroidal neovascularization due to age-related macular degeneration unresponsive to ranibizumab.

METHODS

Prospective noncomparative study. Indication for conversion to aflibercept (2.0 mg) was a failed response to ranibizumab, defined as persistent or recurrent subretinal and/or intraretinal fluid on spectral domain optical coherence tomography. Best-corrected visual acuity (Early Treatment Diabetic Retinopathy Study letter score), fluorescein angiography, indocyanine green angiography, and spectral domain optical coherence tomography were performed at baseline. Patients were followed up monthly, and retreatment was considered at physician discretion based on functional and morphological patterns.

RESULTS

Ninety-two eyes were included in the study. At 12 months, mean best-corrected visual acuity (±SD) change was +1.8 (±10.3), Early Treatment Diabetic Retinopathy Study letters and central retinal thickness (±SD) decreased on average by 112 (±173) μm. Patients received a mean of 3.5 ± 1.8 injections. No significant adverse event was observed during the follow-up.

CONCLUSION

A low number of intravitreal aflibercept injections reversed the preswitching trend toward losing vision and produced stable visual acuity and morphological improvements for up to 12 months in patients with neovascular age-related macular degeneration, not responding to ranibizumab.

Current advances in the treatment of neovascular age-related macular degeneration

INTRODUCTION

Age-related macular degeneration (AMD) is the most common cause of permanent central visual acuity loss in persons over 65 years of age in industrialized nations. Today, intravitreal vascular endothelial growth factor (VEGF) inhibitors are the mainstay of treatment worldwide. Areas covered: The following review covers the current treatments and challenges of wet AMD management. It also covers emerging therapies including radiation, latest generation anti-VEGF agents, and combination therapies. Expert opinion: Current neovascular AMD therapy is aimed at decreasing the VEGF effect at the choroidal neovascularization (CNV) complex. The most important existing challenges in the treatment of neovascular AMD are improving visual outcomes, decreasing the treatment burden, and minimizing geographic atrophy. Clinicians are using many treatment strategies to minimize intravitreal injections without sacrificing visual outcomes. Combination of anti-VEGF therapy with other previously available treatments that target a different pathophysiological mechanism may be a reasonable clinical strategy to minimize intravitreal injections. Many exciting novel drugs that target newly discovered pathways associated with CNV development and progression hold clinical promise. The results of ongoing randomized clinical trials will answer the important concerns surrounding new drugs and delivery devices: safety and visual outcomes.

Advances in pharmacotherapy for wet age-related macular degeneration

INTRODUCTION

In developed countries, neovascular age-related macular degeneration (AMD) is the leading cause of irreversible central blindness. Although AMD pathogenesis is complex and still not fully understood, many involved mechanisms are already partially known and could be promising targets for future therapies. Currently, anti-VEGF drugs are the standard care of this condition.

AREAS COVERED

This review summarizes both the current available and the emerging pharmacological therapies for the management of neovascular AMD. At first, we briefly focused on anti-VEGF compounds that are commonly used. Then, we reviewed the mechanisms of action and potential advantages of new candidate drugs that are being evaluated in clinical trials.

EXPERT OPINION

Although anti-VEGF drugs have shown mild-term good efficacy and safety profile in the treatment of neovascular AMD, they are far away from being a perfect therapy. Pharmacological research should focus on finding new molecular targets in the AMD pathogenetical pathway and on developing longer lasting agents or new drug delivery systems. Besides the development of new drugs, a better characterization of patients is also needed, taking into account variables such as choroidal neovascularization subtypes and genetic factors, in order to identify a tailored treatment for each patient.

Treating the untreatable patient: current options for the management of treatment-resistant neovascular age-related macular degeneration

Anti-vascular endothelial growth factor (anti-VEGF) agents represent the current standard of care for neovascular age-related macular degeneration (nAMD). Although effective in a majority of cases, a significant proportion of patients have persisting retinal exudation despite regular anti-VEGF therapy. This exudation is considered to produce poorer visual outcomes in these patients. Some of these patients may have misdiagnosed nAMD variants such as polypoidal choroidal vasculopathy; however, the majority of these eyes have what has been termed treatment-resistant nAMD. Currently, the best way to care for these patients is uncertain. Here, we review the evidence for different approaches to the management of treatment-resistant nAMD, including high-dose anti-VEGF therapy, combination regimes and switching of anti-VEGF agents, and discuss possible therapeutic approaches for patients with treatment-resistant nAMD.