Ranibizumab and aflibercept for the treatment of wet age-related macular degeneration

Spectral-domain optical coherence tomography combined with electroretinography in the assessment of conbercept for neovascular age-related macular degeneration: a preliminary study

Objective

To observe the effect of three consecutive intravitreal injections of conbercept in the treatment of neovascular age-related macular degeneration (nAMD), to investigate the correlation between retinal anatomy and retinal function by spectral-domain optical coherence tomography (SD-OCT) and electroretinography (ERG), to evaluate the short-term clinical efficacy of conbercept in the treatment of nAMD, and to explore the value of ERG as a predictor of treatment efficacy.

Method

A retrospective investigation was conducted on 36 patients (36 eyes) treated with intravitreal injections of conbercept at 0.5 mg a month for three consecutive courses. Data collected included the best corrected visual acuity (BCVA), central retinal thickness (CRT), retinal pigment epithelium (RPE) elevation volume in 1 mm-diameter (1RV), 3 mm-diameter (3RV), and 6 mm-diameter circles around the fovea (6RV), amplitude density and latency of the P1 wave in the multifocal electroretinography (mf-ERG) R1 ring and amplitude and latency in full-field electroretinography (ff-ERG) at baseline and monthly. The paired t test was used to compare the difference between pre- and posttreatment. Pearson correlation analysis was used to analyze the correlation between macular retinal structure and function. The difference was significant when p < 0.05.

Results

At 12 weeks, the BCVA, CRT, 1RV, 3RV, 6RV, the P1 wave amplitude density of the mf-ERG R1 ring and the ff-ERG amplitude parameters were all significantly improved (p < 0.001). The BCVA in logMAR was positively correlated with CRT; 1RV, 3RV, and 6RV were negatively correlated with the amplitude density and latency of the mf-ERG R1 ring P1 wave. There were no severe ocular or systemic complications during the follow-up period.

Conclusion

Conbercept is useful for the short-term treatment of nAMD. It can safely improve the visual acuity of affected eyes and restore the structure and function of the retina. ERG could serve as an objective indicator of function for evaluating the efficacy of and determining the need for retreatment during nAMD treatment.

Targeting Lipid Metabolism for the Treatment of Age-Related Macular Degeneration: Insights from Preclinical Mouse Models

Age-related macular degeneration (AMD) is a major leading cause of irreversible visual impairment in the world with limited therapeutic interventions. Histological, biochemical, genetic, and epidemiological studies strongly implicate dysregulated lipid metabolism in the retinal pigmented epithelium (RPE) in AMD pathobiology. However, effective therapies targeting lipid metabolism still need to be identified and developed for this blinding disease. To test lipid metabolism-targeting therapies, preclinical AMD mouse models are needed to establish therapeutic efficacy and the role of lipid metabolism in the development of AMD-like pathology. In this review, we provide a comprehensive overview of current AMD mouse models available to researchers that could be used to provide preclinical evidence supporting therapies targeting lipid metabolism for AMD. Based on previous studies of AMD mouse models, we discuss strategies to modulate lipid metabolism as well as examples of studies evaluating lipid-targeting therapeutics to restore lipid processing in the RPE. The use of AMD mouse models may lead to worthy lipid-targeting candidate therapies for clinical trials to prevent the blindness caused by AMD.

[Anti-VEGF therapy for neovascular age-related macular degeneration: causes of incomplete response]

Neovascular age-related macular degeneration (nAMD) is one of the leading causes of decreased vision in the elderly population in many countries, including Russia. Anti-VEGF therapy is undoubtedly the «gold standard» of treatment for the disease, but its use in different patients is known to produce results with significant interindividual differences. This article reviews modern ideas about the clinical assessment of the degree of response to anti-VEGF therapy, possible reasons for its insufficient effectiveness (clinical, pharmacological, or related to nAMD pathogenesis), discusses the potential applications of the existing therapeutic strategies, and considers the prospects for the emergence of new strategies that could be used for solving that problem.

Role of VEGFR2 in Mediating Endoplasmic Reticulum Stress Under Glucose Deprivation and Determining Cell Death, Oxidative Stress, and Inflammatory Factor Expression

Retinal pigment epithelium (RPE), a postmitotic monolayer located between the neuroretina and choroid, supports the retina and is closely associated with vision loss diseases such as age-related macular degeneration (AMD) upon dysfunction. Although environmental stresses are known to play critical roles in AMD pathogenesis and the roles of other stresses have been well investigated, glucose deprivation, which can arise from choriocapillary flow voids, has yet to be fully explored. In this study, we examined the involvement of VEGFR2 in glucose deprivation-mediated cell death and the underlying mechanisms. We found that VEGFR2 levels are a determinant for RPE cell death, a critical factor for dry AMD, under glucose deprivation. RNA sequencing analysis showed that upon VEGFR2 knockdown under glucose starvation, endoplasmic reticulum (ER) stress and unfolded protein response (UPR) are reduced. Consistently, VEGFR2 overexpression increased ER stress under the same condition. Although VEGFR2 was less expressed compared to EGFR1 and c-Met in RPE cells, it could elicit a higher level of ER stress induced by glucose starvation. Finally, downregulated VEGFR2 attenuated the oxidative stress and inflammatory factor expression, two downstream targets of ER stress. Our study, for the first time, has demonstrated a novel role of VEGFR2 in RPE cells under glucose deprivation, thus providing valuable insights into the mechanisms of AMD pathogenesis and suggesting that VEGFR2 might be a potential therapeutic target for AMD prevention, which may impede its progression.

Self-Assembling Tacrolimus Nanomicelles for Retinal Drug Delivery

Neovascular age-related macular degeneration (AMD) is characterized by an increase in reactive oxygen species (ROS) and pro-inflammatory cytokines in the retinal pigment epithelium cells. The primary purpose of this study was the development of a clear, tacrolimus nanomicellar formulation (TAC-NMF) for AMD. The optimized formulation had a mean diameter of 15.41 nm, a zeta potential of 0.5 mV, and an entrapment efficiency of 97.13%. In-vitro cytotoxicity studies revealed the dose-dependent cytotoxicity of TAC-NMF on various ocular cell lines, such as human retinal pigment epithelium (D407), monkey retinal choroidal endothelial (RF/6A) cells, and human corneal epithelium (CCL 20.2) cells. Cellular uptake and in-vitro distribution studies using flow cytometry and confocal microscopy, respectively, indicated an elevated uptake of TAC-NMF in a time-dependent manner. Biocompatibility assay using macrophage RAW 264.7 cell line resulted in low production of inflammatory cytokines such as IL-6, IL-1β and TNF-α after treatment with TAC-NMF. There was a decrease in ROS in D407 cells pre-treated with sodium iodate (ROS inducing agent) after treating with TAC-NMF and tacrolimus drug. Similarly, there was a reduction in the pro-inflammatory cytokines and VEGF-A in D407 cells pretreated with sodium iodate. This indicates that TAC-NMF could lower pro-inflammatory cytokines and ROS commonly seen in AMD.

Adding a Corticosteroid or Switching to Another Anti-VEGF in Insufficiently Responsive Wet Age-Related Macular Degeneration

Purpose

To compare the effect of adding a corticosteroid or switching to another anti-VEGF treatment in patients with exudative age-related macular degeneration (eAMD) with persisting intraretinal fluid on anti-VEGF monotherapy.

Methods

This retrospective, interventional case series involved 43 pseudophakic eyes with eAMD and persistent intraretinal fluid on anti-VEGF treatment that switched treatment to a combination of Ozurdex^® or Triamcinolone and anti-VEGF therapy (group 1) or to another anti-VEGF agent (group 2). The number of injections, time to re-injection, change in central retinal thickness (CRT), and best-corrected visual acuity (BCVA) from 12 months prior to 12 months after switch to third-line therapy were defined as primary outcomes.

Results

Whereas the treatment demand was reduced (from 8.8±2.2 to 4.6±2.9 injections; p=0.001) and the re-injection interval extended in group 1 (from 1.5±0.4 months to 4.4±3.8 months; p=0.001), these parameters did not change in group 2 (7.4±1.6 to 7.3±2.2; p=0.90 and 1.7±0.3 months to 1.9±0.8 months; p=0.75). Mean CRT decreased from 455.7±30.1 and 427.6±36.0µm (groups 1 and 2, respectively) to 359.1±38.2 and 303.1±44.4µm (intergroup p=0.03). The mean baseline BCVA of 62.6±3.8 letters (group 1) and 63.0±1.9 letters (group 2) remained stable under therapy in both groups (intergroup p=0.67).

Conclusion

In eyes with eAMD with persistent intraretinal fluid on anti-VEGF monotherapy despite frequent re-injections, corticosteroids achieved a similar functional and morphological outcome over 12 months as switching to another anti-VEGF therapy, but with a reduced injection burden. In selected cases, corticosteroid treatment may thus be an option for third-line therapy in refractory exudative AMD.

Time course of swept-source optical coherence tomography angiography findings after photodynamic therapy and aflibercept in eyes with age-related macular degeneration

Purpose

To report swept-source optical coherence tomography angiography (SS-OCTA) findings after full-fluence photodynamic therapy (PDT) and aflibercept intravitreal injection (IVA) for age-related macular degeneration (AMD).

Methods

Five eyes of five patients with AMD treated with PDT and IVA were include into the study. We retrospectively reviewed the data obtained from the five patients using SS-OCTA before and after treatment. Three eyes had type 1 choroidal neovascularization (CNV) and two eyes had polypoidal choroidal vasculopathy.

Results

Before treatment, the CNV signals detected in all cases, decreased in three eyes and were not detected completely in two eyes at 1 months after treatment. The areas indicating CNV increased over time, but they did not increase to the baseline level. No CNV signal was detected in one eye during follow-up. In all cases, the exudation unchanged or resolved without additional IVA; the exudation recurred in two cases. In one eye, the CNV signal and the exudation occurred simultaneously; however, there was no association in another eye. A feeder vessel, from which the CNV signal seemed to originate, was seen in one of the five eyes.

Conclusion and Importance

SS-OCTA is useful to monitor the morphology of CNV after PDT and IVA, indicating that the remodeling of the choroidal vasculature occurs gradually after treatment. The presence or absence of the CNV signal might indicate CNV activity.

Aflibercept: A review of its effect on the treatment of exudative age-related macular degeneration

Considerable improvement has been achieved in the way in which exudative age-related macular degeneration is conventionally treated and in the associated visual outcomes and prognosis, thanks to the agents with effects against vascular endothelial growth factor (anti-VEGF). By comparison to earlier treatment approaches that involved the use of lasers, the anti-VEGF agents have made it possible to accomplish more positive visual and anatomical outcomes in cases of exudative age-related macular degeneration. Indeed, owing to their positive effects, anti-VEGF agents have quickly come to be considered the gold standard for the treatment of wet age-related macular degeneration. Aflibercept, the most recently approved intravitreally administered anti-VEGF, seems to mark another milestone in the treatment of wet age-related macular degeneration. This anti-VEGF agent presents a series of singular pharmacodynamic and pharmacokinetic attributes that provide it a number of biological benefits in relation to the treatment of choroidal neovascularization compared to other agents. These attributes include high level of affinity for the VEGF-A factor, an intravitreal half-life of great length, as well as the ability to serve as an antagonist for other growth factors besides VEGF. The impact of Aflibercept on the manner in which exudative age-related macular degeneration is managed was demonstrated by thoroughly reviewing the related literature. The present review article highlights the pharmacology, pharmacokinetics, safety and effectiveness of this anti-VEGF agent as well as the landmark clinical studies that have been carried out to establish this drug as a gold standard in the therapy of neovascular age-related macular degeneration. In addition, studies regarding the outcomes and effectiveness of the various dosage regimens, either as monotherapy or in combination with other agents, are also reviewed.

The cost-effectiveness of systematic screening for age-related macular degeneration in South Korea

Background

Interventions that can facilitate early diagnosis of age-related macular degeneration (AMD) will facilitate early treatment and improve clinical outcomes but there has been concerns about additional medical costs to the health care system. An examination through a retina fundus photography by a non-specialist has been suggested as a potential cost-effective alternative to a direct examination by a specialist, but limited scientific data exists on the cost-effectiveness of screening strategies for AMD. Our objective is to conduct an economic evaluation of various population-wide screening strategies for AMD among the South Korean population.

Methods and findings

Using a Markov cohort model, we evaluated the cost-effectiveness of four AMD screening strategies (opportunistic examination, opportunistic treatment, systematic photography, and systematic examination) in comparison with status quo (no screening) for South Korean adults. We projected a life time horizon to study a hypothetical cohort of 100,00 persons of age 40 with and without AMD at baseline. The outcome measures were quality-adjusted life-years (QALYs) gained, cost from the societal perspective, and the incremental cost-effectiveness ratio (ICER) of each strategy. Interventions were evaluated at a willingness-to-pay (WTP) threshold of 30,000,000 KRW ($27,538) per QALY gained. Deterministic and probabilistic sensitivity analyses were conducted to address the model uncertainty. Opportunistic examination was strongly dominated because it generated fewer expected QALYs but incurred greater expected cost than the other screening strategies. The mean lifetime expected costs were 289,013 KRW, 363,692 KRW, 9,351,964 KRW, and 12,309,783 KRW, and the mean QALYs gained were 37.73, 37.75, 40.47, 40.68, for no screening, opportunistic treatment, systematic photography, and systematic examination, respectively. The results were most sensitive to the utility weight of mild AMD, the probability of complication from treatment, the cost of being in mild AMD, and the probability of recovery from complication. After eliminating the two weakly dominated strategies, systematic photography was cost-effective at the ICER of 3,310,448 KRW per QALY in comparison to status quo.

Conclusions

Under the WTP threshold of 30,000,000 KRW per QALY, systematic photography is cost-effective for screening AMD in South Korean adults. Systematic examination by ophthalmologists generates more expected QALY and cost compared to systematic photography.

The Bioactivity of D-/L-Isonucleoside- and 2'-Deoxyinosine-Incorporated Aptamer AS1411s Including DNA Replication/MicroRNA Expression

In this study, chemical modification of 2'-deoxyinosine (2'-dI) and D-/L-isothymidine (D-/L-isoT) was performed on AS1411. They could promote the nucleotide-protein interaction by changing the local conformation. Twenty modified sequences were obtained, FCL-I and FCL-II showed the most noticeable activity improvement. They stabilized the G-quadruplex, remained highly resistant to serum degradation and specificity for nucleolin, further inhibited tumor cell growth, exhibited a stronger ability to influence the different phases of the tumor cell cycle, induced S-phase arrest, promoted the inhibition of DNA replication, and suppressed the unwound function of a large T antigen as powerful as AS1411. The microarray analysis and TaqMan PCR results showed that FCL-II can upregulate the expression of four breast-cancer-related, lowly expressed miRNAs and downregulate the expression of three breast-cancer-related, highly expressed miRNAs (>2.5-fold). FCL-II resulted in enhanced treatment effects greater than AS1411 in animal experiments (p < 0.01). The computational results further proved that FCL-II exhibits more structural advantages than AS1411 for binding to the target protein nucleolin, indicating its great potential in antitumor therapy.

Ig-like domain 6 of VCAM-1 is a potential therapeutic target in TNFα-induced angiogenesis

Tumor necrosis factor alpha (TNFα)-induced angiogenesis plays important roles in the progression of various diseases, including cancer, wet age-related macular degeneration, and rheumatoid arthritis. However, the relevance and role of vascular cell adhesion molecule-1 (VCAM-1) in angiogenesis have not yet been clearly elucidated. In this study, VCAM-1 knockdown shows VCAM-1 involvement in TNFα-induced angiogenesis. Through competitive blocking experiments with VCAM-1 Ig-like domain 6 (VCAM-1-D6) protein, we identified VCAM-1-D6 as a key domain regulating TNFα-induced vascular tube formation. We demonstrated that a monoclonal antibody specific to VCAM-1-D6 suppressed TNFα-induced endothelial cell migration and tube formation and TNFα-induced vessel sprouting in rat aortas. We also found that the antibody insignificantly affected endothelial cell viability, morphology and activation. Finally, the antibody specifically blocked VCAM-1-mediated cell–cell contacts by directly inhibiting VCAM-1-D6-mediated interaction between VCAM-1 molecules. These findings suggest that VCAM-1-D6 may be a potential novel therapeutic target in TNFα-induced angiogenesis and that antibody-based modulation of VCAM-1-D6 may be an effective strategy to suppress TNFα-induced angiogenesis.

Efficacy and safety of a fixed bimonthly ranibizumab treatment regimen in eyes with neovascular age-related macular degeneration: results from the RABIMO trial

PURPOSE

To evaluate prospectively the efficacy and safety of a fixed bimonthly ranibizumab treatment regimen (RABIMO) in eyes with neovascular age-related macular degeneration (nAMD) and to compare these results with a pro re nata (PRN) treatment scheme.

METHODS

This was a 12-month, phase IV, single center, randomised, non-inferiority study. Following three initial monthly injections, patients were randomised to receive either ranibizumab bimonthly (RABIMO group) or ranibizumab PRN (PRN group) (n = 20 each). Main outcome measures were best-corrected visual acuity (BCVA), central retinal thickness (CRT), number of injections, and adverse events (AEs).

RESULTS

BCVA [median (interquartile range, IQR)] increased significantly in both groups after 12 months [RABIMO group +8.5 (14); PRN group +6.5 (16) ETDRS letters] when compared to baseline (p < 0.0001; p = 0.0085). At month 12, the RABIMO treatment regimen was non-inferior to the PRN scheme (∆BCVA = 3.5 ETDRS letters; p < 0.0001). CRT was significantly reduced in both groups after the 12-month study period (p < 0.0001 each), with no significant difference between groups (p = 0.6772). Number of overall injections [median (IQR)] was 8 (0) in the RABIMO versus 4 (5) in the PRN group (p = 0.0037). Three patients in the RABIMO group received one additional unscheduled injection. We observed no significant differences between groups in the number of patients with reported SAEs/AEs (RABIMO group n = 6/15; PRN group n = 7/13) (p = 0.7357/p = 0.4902).

CONCLUSIONS

We found no evidence of significant functional or anatomical differences between the RABIMO and PRN treatment regimens. However, the RABIMO group's number of injections was twice as high as the PRN group's (protocol-driven). In light of potential side effects, the fixed bimonthly treatment regimen might not be advisable for routine clinical care, but it might be a worthwhile treatment option if monthly monitoring is not possible. Eudra-CT number: 2009-017324-11.

MicroRNA-processing Enzymes Are Essential for Survival and Function of Mature Retinal Pigmented Epithelial Cells in Mice

Age-related macular degeneration (AMD) is a major cause of irreversible vision loss. The neovascular or "wet" form of AMD can be treated to varying degrees with anti-angiogenic drugs, but geographic atrophy (GA) is an advanced stage of the more prevalent "dry" form of AMD for which there is no effective treatment. Development of GA has been linked to loss of the microRNA (miRNA)-processing enzyme DICER1 in the mature retinal pigmented epithelium (RPE). This loss results in the accumulation of toxic transcripts of Alu transposable elements, which activate the NLRP3 inflammasome and additional downstream pathways that compromise the integrity and function of the RPE. However, it remains unclear whether the loss of miRNA processing and subsequent gene regulation in the RPE due to DICER1 deficiency also contributes to RPE cell death. To clarify the role of miRNAs in RPE cells, we used two different mature RPE cell-specific Cre recombinase drivers to inactivate either Dicer1 or DiGeorge syndrome critical region 8 (Dgcr8), thus removing RPE miRNA regulatory activity in mice by disrupting two independent and essential steps of miRNA biogenesis. In contrast with prior studies, we found that the loss of each factor independently led to strikingly similar defects in the survival and function of the RPE and retina. These results suggest that the loss of miRNAs also contributes to RPE cell death and loss of visual function and could affect the pathology of dry AMD.

Resistance to anti-VEGF therapy in neovascular age-related macular degeneration: a comprehensive review

As a progressive chronic disease, age-related macular degeneration (AMD) is the leading cause of irreversible vision impairment worldwide. Experimental and clinical evidence has demonstrated that vascular endothelial growth factor (VEGF) plays a vital role in the formation of choroidal neovascularization. Intravitreal injections of anti-VEGF agents have been recommended as a first-line treatment for neovascular AMD. However, persistent fluid or recurrent exudation still occurs despite standardized anti-VEGF therapy. Patients suffering from refractory or recurrent neovascular AMD may develop mechanisms of resistance to anti-VEGF therapy, which results in a diminished therapeutic effect. Until now, there has been no consensus on the definitions of refractory neovascular AMD and recurrent neovascular AMD. This article aims at clarifying these concepts to evaluate the efficacy of switching drugs, which contributes to making clinical decision more scientifically. Furthermore, insight into the causes of resistance to anti-VEGF therapy would be helpful for developing possible therapeutic approaches, such as combination therapy and multi-target treatment that can overcome this resistance.