Comprehensive Preclinical Assessment of ADVM-022, an Intravitreal Anti-VEGF Gene Therapy for the Treatment of Neovascular AMD and Diabetic Macular Edema

Advancements in age-related macular degeneration treatment: From traditional anti-VEGF to emerging therapies in gene, stem cell, and nanotechnology

Age-related macular degeneration (AMD) is the leading cause of central vision loss in older adults and is projected to affect approximately 400 million individuals worldwide by 2040. Its pathological characteristics include retinal extracellular deposits, such as drusen, which trigger photoreceptor degeneration and damage to the retinal pigment epithelium (RPE), resulting in irreversible vision loss. The pathogenesis of AMD involves genetic, environmental, and aging-related factors. Anti-vascular endothelial growth factor (anti-VEGF) therapy for wet AMD significantly inhibits choroidal neovascularization and delays visual deterioration. However, its high cost, frequent injections, and poor patient compliance limit application, and there remains no effective intervention for dry AMD. In recent years, emerging strategies, such as gene therapy, stem cell therapy, and nanotechnology-based drug delivery systems, offer hope for slowing disease progression by improving targeting, drug stability, and reducing treatment frequency. Nanoparticles, including polymeric and lipid systems, have shown promise for enhancing drug delivery and bioavailability, particularly for dry AMD, where existing therapies are inadequate. These strategies also have the potential to improve patient compliance. This review summarizes AMD epidemiology and examines the limitations of current therapies. It emphasizes the mechanisms and clinical advancements of gene therapy, stem cell therapy, and nanotechnology in AMD treatment. These emerging technologies offer promising opportunities for precision medicine and lay a solid foundation for the future development of multifaceted therapeutic strategies.

Gene therapy in neovascular age related macular degeneration: an update

Neovascular age-related macular degeneration (NV-AMD) is a leading cause of preventable blindness in the elderly. Intravitreal injections of anti-VEGF agents are currently the treatment of choice for NV-AMD. However this treatment is burdensome and fosters non-compliance which leads to inferior visual outcomes. Gene therapy has emerged as a promising therapeutic option for NV-AMD that may improve these outcomes. Potential risks of gene therapy include a potential immune response that may be elicited by the vector, accidental activation of oncogenes or inactivation of tumor suppresor genes leading to malignant transformation via insertational mutagenesis and integration of the viral DNA inserts into the host's DNA. The main strategy of current gene therapy for NV-AMD has focused on delivering transgenes that express anti-angiogenic proteins that directly or indirectly inhibit the VEGF pathway. Ixoberogene soroparvovec, RGX-314 and 4D-150 are the leading NV-AMD genetic treatment programs. Pre-clinical models suggest that genome surgery with clustered regularly interspaced short palindromic repeats (CRISPR) may be another option in the future.

Efficacy, Safety, and Injection Frequency with Novel Aflibercept 8 mg in Neovascular Age-Related Macular Degeneration: A Comparison with Existing Anti-VEGF Regimens Using a Bayesian Network Meta-Analysis

INTRODUCTION

Aflibercept 8 mg administered in extended dosing intervals has shown non-inferior visual gains and comparable safety profile to aflibercept 2 mg in the PULSAR pivotal randomized clinical trial and has the potential to reduce the treatment burden of treating neovascular age-related macular degeneration (nAMD). This study aimed at gathering robust evidence to assess the comparative efficacy, safety, and treatment burden of aflibercept 8 mg against other anti-vascular endothelial growth factor (VEGF) agents as ranibizumab, brolucizumab, faricimab, and bevacizumab in patients with nAMD.

METHODS

A systematic literature review (SLR) was conducted, targeting clinical trials of anti-VEGF agents in patients with nAMD. The results of the SLR were included in a network meta-analysis (NMA) comparing aflibercept 8 mg to other anti-VEGF treatments in nAMD, considering a 1-year time horizon. Treatment efficacy was assessed based on the change in best-corrected visual acuity (BCVA) from baseline, the proportion of patients gaining or losing 15 Early Treatment Diabetic Retinopathy Study (ETDRS) letters and changes in anatomical outcomes measured as change in central retinal thickness (CRT) or central subfield thickness (CST). Safety was assessed considering the incidence of ocular and non-ocular adverse events. Treatment burden was defined as the mean number of intravitreal injections over the study period.

RESULTS

The base-case NMA involving 21 studies did not show significant differences between aflibercept 8 mg and comparators regarding BCVA change from baseline and proportion of patients with a gain or loss of ≥ 15 letters. On the anatomical endpoints, aflibercept 8 mg was associated with statistically significant improvement in CRT/CST change from baseline compared with ranibizumab in fixed and pro re nata regimens. No significant differences were identified versus the other anti-VEGF. The analysis of the safety outcomes did not identify any significant differences between aflibercept 8 mg and any of the comparators. During the first year of treatment, patients treated with aflibercept 8 mg (following 12- or 16-week injection intervals) received on average 5.9 and 5.1 injections, respectively. For the same period, patients treated with faricimab received from 6.2 to 6.7 injections, patients treated with ranibizumab from 7.62 to 12.14 injections, and patients treated with aflibercept 2 mg up to 7.67 injections.

CONCLUSION

Aflibercept 8 mg demonstrates a comparable efficacy and safety to currently available anti-VEGF treatments for nAMD, with the potential added benefit of requiring fewer injections. These results suggest that aflibercept 8 mg could be a favourable treatment option for nAMD, achieving sustained disease control while alleviating the burden of injections on patients, caregivers, and healthcare providers.

Nonclinical study of ixo-vec gene therapy for nAMD supports efficacy for a human dose of 6E10 vg/eye and staggered dosing of fellow eyes

Ixoberogene soroparvovec (ixo-vec), formerly ADVM-022, is an adeno-associated virus (AAV) gene therapy using the AAV.7m8 capsid for intravitreal delivery (IVT) to transduce retinal tissue and produce sustained intraocular aflibercept for treating neovascular age-related macular degeneration (nAMD). Non-clinical studies show that aflibercept production by ixo-vec is less than dose proportional, while intraocular inflammation (IOI) increases with dose, suggesting that lower doses could yield effective aflibercept levels with reduced IOI risk. Our evaluation confirmed that doses as low as 3E10 vg (vector genome)/eye (6E10 vg/eye human equivalent) maintained effective aflibercept production. The concept behind ADVM-022 is supported by clinical studies OPTIC (NCT03748784) and LUNA (NCT05536973), where a single IVT administration eliminated or significantly reduced the need for additional anti-VEGF injections in patients. Moreover, LUNA confirmed the clinical efficacy of a 6E10-vg/eye dose, demonstrating robust and sustained aflibercept levels. Additionally, we evaluated staggered dosing in contralateral eyes to treat asynchronous disease development. Staggered dosing, administered 2 months apart, did not exacerbate IOI, and both eyes maintained therapeutic aflibercept levels. These findings support the tolerability and efficacy of staggered dosing, indicating the potential for bilaterally relevant aflibercept levels with ixo-vec, due to immune response confinement to the dosed eye.

Advances in the Study of Age-Related Macular Degeneration Based on Cell or Cell-Biomaterial Scaffolds

Age-related macular degeneration (AMD), a progressive neurodegenerative disorder affecting the central retina, is pathologically defined by the irreversible degeneration of photoreceptors and retinal pigment epithelium (RPE), coupled with extracellular drusen deposition and choroidal neovascularization (CNV), and AMD constitutes the predominant etiological factor for irreversible vision impairment in adults aged ≥60 years. Cell-based or cell-biomaterial scaffold-based approaches have been popular in recent years as a major research direction for AMD; monotherapy with cell-based approaches typically involves subretinal injection of progenitor-derived or stem cell-derived RPE cells to restore retinal homeostasis. Meanwhile, cell-biomaterial scaffolds delivered to the lesion site by vector transplantation have been widely developed, and the implanted cell-biomaterial scaffolds can promote the reintegration of cells at the lesion site and solve the problems of translocation and discrete cellular structure produced by cell injection. While these therapeutic strategies demonstrate preliminary efficacy, rigorous preclinical validation and clinical trials remain imperative to validate their long-term safety, functional durability, and therapeutic consistency. This review synthesizes current advancements and translational challenges in cell-based and cell-biomaterial scaffold approaches for AMD, aiming to inform future development of targeted interventions for AMD pathogenesis and management.

Preclinical evaluation of NG101, a potential AAV gene therapy for wet age-related macular degeneration

Age-related macular degeneration (AMD) is a leading cause of vision loss in individuals over the age of 55. Approximately 10%-15% of AMD patients develop choroidal neovascularization (CNV), leading to wet AMD (wAMD), which accounts for nearly 90% of AMD-related blindness. Inhibition of vascular endothelial growth factor (VEGF) is the standard treatment for wAMD. However, the frequent administration of the current treatment imposes a significant burden on wAMD patients. Therefore, there is an unmet need for treatments that require less-frequent administration. Here, we present findings on the safety and efficacy of NG101, a recombinant adeno-associated virus (rAAV) vector encoding aflibercept, an anti-VEGF agent, for wAMD therapy. A single subretinal injection of NG101 effectively reduced CNV lesion leakage and size at doses as low as 1 × 106 in mouse and 3 × 109 viral genomes per eye in cynomolgus monkeys. In cynomolgus monkeys, NG101-derived aflibercept expression in ocular tissues persisted for 1 year post-injection, indicating sustained therapeutic potential. Biodistribution analysis revealed that NG101 was primarily localized in ocular tissues. Only mild and transient ocular inflammatory responses were observed. Overall, these findings suggest that NG101, with its efficacy at low doses and sustained expression, is a promising therapeutic candidate for wAMD.

VEGF-Virus Interactions: Pathogenic Mechanisms and Therapeutic Applications

Many types of viruses directly or indirectly target the vascular endothelial growth factor (VEGF) system, which is a central regulator of vasculogenesis and angiogenesis in physiological homeostasis, causing diverse pathologies. Other viruses have been developed into effective therapeutic tools for VEGF modulation in conditions such as cancer and eye diseases. Some viruses may alter the levels of VEGF in the pathogenesis of respiratory syndromes, or they may encode VEGF-like factors, promoting vascular disruption and angiogenesis to enable viruses' systemic spread. Oncogenic viruses may express interactive factors that perturb VEGF's functional levels or downstream signaling, which increases the neovascularization and metastasis of tumors. Furthermore, many viruses are being developed as therapeutic vectors for vascular pathologies in clinical trials. Major examples are those viral vectors that inhibit the role of VEGF in the neovascularization required for cancer progression; this is achieved through the induction of immune responses, by exposing specific peptides that block signaling or by expressing anti-VEGF and anti-VEGF receptor-neutralizing antibodies. Other viruses have been engineered into effective pro- or anti-angiogenesis multitarget vectors for neovascular eye diseases, paving the way for therapies with improved safety and minimal side effects. This article critically reviews the large body of literature on these issues, highlighting those contributions that describe the molecular mechanisms, thus expanding our understanding of the VEGF-virus interactions in disease and therapy. This could facilitate the clinical use of therapeutic virus vectors in precision medicine for the VEGF system.

Suppression of matrigel-induced choroidal neovascularization by AAV delivery of a novel anti-Scg3 antibody

Efforts to develop gene therapy for long-term treatment of neovascular disease are hampered by ongoing concerns that biologics against vascular endothelial growth factor (VEGF) inhibit both physiological and pathological angiogenesis and are therefore at elevated risk of adverse side effects. A potential solution is to develop disease-targeted gene therapy. Secretogranin III (Scg3), a unique disease-restricted angiogenic factor described by our group, contributes significantly to ocular neovascular disease. We have shown that Scg3 blockade with a monoclonal antibody Fab fragment (Fab) stringently inhibits pathological angiogenesis without affecting healthy vessels. Here we tested the therapeutic efficacy of adeno-associated virus (AAV)-anti-Scg3Fab to block choroidal neovascularization (CNV) induced by subretinal injection of Matrigel in a mouse model. Intravitreal AAV-anti-Scg3Fab significantly reduced CNV and suppressed CNV-associated leukocyte infiltration and macrophage activation. The efficacy and anti-inflammatory effects were equivalent to those achieved by positive control AAV-aflibercept against VEGF. Efficacies of AAV-anti-Scg3Fab and AAV-aflibercept were sustained over 4 months post AAV delivery. The findings support development of AAV-anti-Scg3 as an alternative to AAV-anti-VEGF with equivalent efficacy and potentially safer mechanism of action.

Gene and cell therapy for age-related macular degeneration: A review

Age-related macular degeneration (AMD) is the most common cause of irreversible vision loss among the elderly in Western communities, with an estimated global prevalence of 10 - 20% in people older than 65 years. AMD leads to central vision loss due to degeneration of the photoreceptors, retinal pigment epithelium and the choriocapillaris. Beckman's classification for AMD, based upon color fundus photographs, divides the disease into early, intermediate, and late forms. The late, vision-threatening stage includes both neovascular AMD and geographic atrophy. Despite its high prevalence and impact on patients' quality of life, treatment options for AMD are limited. While neovascular AMD can be medically managed with anti-VEGF intravitreal injections, until very recently there has been no approved treatment options for atrophic AMD; however, in February 2023 the first treatment for geographic atrophy - pegcetacoplan - was approved by the US FDA. We describe the current landscape of potential gene and cell therapeutic strategies for late-stage AMD, with an emphasis on the therapeutic options that might become available in the next few years.

Long-acting delivery and therapies for neovascular age-related macular degeneration

INTRODUCTION

Neovascular age-related macular degeneration (nAMD) represents a leading cause of severe visual impairment in individuals over 50 years of age in developed nations. Intravitreal anti-vascular endothelial growth factor (VEGF) injections have become the standard of care for treating nAMD; however, monthly or bimonthly dosing represents significant time and cost burden due to the disease's chronic nature and limited medication half-life.

AREAS COVERED

This review summarizes innovative therapeutics and delivery methods for nAMD. Emerging methods for extended drug delivery include high molar concentration anti-VEGF drugs, intravitreal sustained-release polymers and devices, reservoirs for intravitreal delivery, suprachoroidal delivery of small molecular suspensions and gene therapy biofactories. In addition to VEGF-A, therapies targeting inhibition of VEGF-C and D, the angiopoetin-2 (Ang-2)/Tie-2 pathway, tyrosine kinases, and integrins are reviewed.

EXPERT OPINION

The evolving therapeutic landscape of nAMD is rapidly expanding our toolkit for effective and durable treatment. Recent FDA approvals of faricimab (Vabysmo) and high-dose aflibercept (Eylea HD) for nAMD with potential extension of injection intervals up to four months have been promising developments for patients and providers alike. Further research and innovation, including novel delivery techniques and pharmacologic targets, is necessary to validate the efficacy of developing therapeutics and characterize real-world outcomes, demonstrating promise in expanding treatment durability.

Gene therapy for retinal diseases: From genetics to treatment

The gene therapy approach for retinal disorders has been considered largely over the last decade owing to the favorable outcomes of the US Food and Drug Administration-approved commercial gene therapy, Luxturna. Technological advances in recent years, such as next-generation sequencing, research in molecular pathogenesis of retinal disorders, and precise correlations with their clinical phenotypes, have contributed to the progress of gene therapies for various diseases worldwide, and more recently in India as well. Thus, considerable research is being conducted for the right choice of vectors, transgene engineering, and accessible and cost-effective large-scale vector production. Many retinal disease-specific clinical trials are presently being conducted, thereby necessitating the collation of such information as a ready reference for the scientific and clinical community. In this article, we present an overview of existing gene therapy research, which is derived from an extensive search across PubMed, Google Scholar, and clinicaltrials.gov sources. This contributes to prime the understanding of basic aspects of this cutting-edge technology and information regarding current clinical trials across many different conditions. This information will provide a comprehensive evaluation of therapies in existing use/research for personalized treatment approaches in retinal disorders.

Summary of the Therapeutic Options for Patients with Dry and Neovascular AMD

Age-related macular degeneration (AMD) is the leading cause of irreversible blindness worldwide and a severe medical and social problem. The steadily increasing number of patients is related to the aging of the population. So far, many factors affecting the development of AMD have been identified, which can be divided into non-modifiable, including genetic factors, age, and sex, and modifiable or environmental factors, such as smoking, poor diet, and hypertension. Early stages of age-related macular degeneration are characterized by fundus drusen and abnormalities in the retinal pigment epithelium. In late stages, geographic atrophy and choroidal neovascularization (CNV) are observed. The treatment of AMD, especially its advanced forms, is very challenging. Intensive research has made it possible to treat advanced stages of the dry form of AMD with pegcetacoplan and avacincaptad pegol, new drugs approved for use in the US. Pegcetacoplan targets the C3 and avacincaptad pegol targets the C5, the pivotal proteins of the complement cascade. The drugs are administered by intravitreal injection. The gold standard for neovascular AMD (nAMD) consists of intravitreal injections of anti-vascular endothelial growth factor (anti-VEGF) drugs such as bevacizumab, ranibizumab, aflibercept, brolucizumab, and faricimab. Treatment can be administered according to the fixed, pro-re-nata, and treat-and-extend regimens. The latter seems to have the best effect on improving visual acuity (VA) and the maximum therapeutic benefit. The search continues for the best ways to deliver intravitreal drugs. Current methods include sustained-release implants and hydrogel platforms for drug release, while the most promising future pathways for treating dry and nAMD are stem cell and gene therapy.

Genetic Insights into Age-Related Macular Degeneration

One of the major causes of vision impairment among elderly people in developed nations is age-related macular degeneration (AMD). The distinctive features of AMD are the accumulation of extracellular deposits called drusen and the gradual deterioration of photoreceptors and nearby tissues in the macula. AMD is a complex and multifaceted disease influenced by several factors such as aging, environmental risk factors, and a person's genetic susceptibility to the condition. The interaction among these factors leads to the initiation and advancement of AMD, where genetic predisposition plays a crucial role. With the advent of high-throughput genotyping technologies, many novel genetic loci associated with AMD have been identified, enhancing our knowledge of its genetic architecture. The common genetic variants linked to AMD are found on chromosome 1q32 (in the complement factor H gene) and 10q26 (age-related maculopathy susceptibility 2 and high-temperature requirement A serine peptidase 1 genes) loci, along with several other risk variants. This review summarizes the common genetic variants of complement pathways, lipid metabolism, and extracellular matrix proteins associated with AMD risk, highlighting the intricate pathways contributing to AMD pathogenesis. Knowledge of the genetic underpinnings of AMD will allow for the future development of personalized diagnostics and targeted therapeutic interventions, paving the way for more effective management of AMD and improved outcomes for affected individuals.

Gene Therapy for Non-Hereditary Retinal Disease: Age-Related Macular Degeneration, Diabetic Retinopathy, and Beyond

Gene therapy holds promise as a transformative approach in the treatment landscape of age-related macular degeneration (AMD), diabetic retinopathy (DR), and diabetic macular edema (DME), aiming to address the challenges of frequent intravitreal anti-vascular endothelial growth factor (VEGF) injections. This manuscript reviews ongoing gene therapy clinical trials for these disorders, including ABBV-RGX-314, ixoberogene soroparvovec (ixo-vec), and 4D-150. ABBV-RGX-314 utilizes an adeno-associated virus (AAV) vector to deliver a transgene encoding a ranibizumab-like anti-VEGF antibody fragment, demonstrating promising results in Phase 1/2a and ongoing Phase 2b/3 trials. Ixo-vec employs an AAV2.7m8 capsid for intravitreal delivery of a transgene expressing aflibercept, showing encouraging outcomes in Phase 1 and ongoing Phase 2 trials. 4D-150 utilizes an evolved vector to express both aflibercept and a VEGF-C inhibitory RNAi, exhibiting positive interim results in Phase 1/2 studies. Other therapies reviewed include EXG102-031, FT-003, KH631, OLX10212, JNJ-1887, 4D-175, and OCU410. These therapies offer potential advantages of reduced treatment frequency and enhanced safety profiles, representing a paradigm shift in management towards durable and efficacious cellular-based biofactories. These advancements in gene therapy hold promise for improving outcomes in AMD and addressing the complex challenges of DME and DR, providing new avenues for the treatment of diabetic eye diseases.

A New Generation of Gene Therapies as the Future of Wet AMD Treatment

Age-related macular degeneration (AMD) is an eye disease and the most common cause of vision loss in the Western World. In its advanced stage, AMD occurs in two clinically distinguished forms, dry and wet, but only wet AMD is treatable. However, the treatment based on repeated injections with vascular endothelial growth factor A (VEGFA) antagonists may at best stop the disease progression and prevent or delay vision loss but without an improvement of visual dysfunction. Moreover, it is a serious mental and financial burden for patients and may be linked with some complications. The recent first success of intravitreal gene therapy with ADVM-022, which transformed retinal cells to continuous production of aflibercept, a VEGF antagonist, after a single injection, has opened a revolutionary perspective in wet AMD treatment. Promising results obtained so far in other ongoing clinical trials support this perspective. In this narrative/hypothesis review, we present basic information on wet AMD pathogenesis and treatment, the concept of gene therapy in retinal diseases, update evidence on completed and ongoing clinical trials with gene therapy for wet AMD, and perspectives on the progress to the clinic of "one and done" therapy for wet AMD to replace a lifetime of injections. Gene editing targeting the VEGFA gene is also presented as another gene therapy strategy to improve wet AMD management.

AAV-Based Strategies for Treatment of Retinal and Choroidal Vascular Diseases: Advances in Age-Related Macular Degeneration and Diabetic Retinopathy Therapies

Age-related macular degeneration (AMD) and diabetic retinopathy (DR) are vascular diseases with high prevalence, ranking among the leading causes of blindness and vision loss worldwide. Despite being effective, current treatments for AMD and DR are burdensome for patients and clinicians, resulting in suboptimal compliance and real risk of vision loss. Thus, there is an unmet need for long-lasting alternatives with improved safety and efficacy. Adeno-associated virus (AAV) is the leading vector for ocular gene delivery, given its ability to enable long-term expression while eliciting relatively mild immune responses. Progress has been made in AAV-based gene therapies for not only inherited retinal diseases but also acquired conditions with preclinical and clinical studies of AMD and DR showing promising results. These studies have explored several pathways involved in the disease pathogenesis, as well as different strategies to optimise gene delivery. These include engineered capsids with enhanced tropism to particular cell types, and expression cassettes incorporating elements for a targeted and controlled expression. Multiple-acting constructs have also been investigated, in addition to gene silencing and editing. Here, we provide an overview of strategies employing AAV-mediated gene delivery to treat AMD and DR. We discuss preclinical efficacy studies and present the latest data from clinical trials for both diseases.

Safety and efficacy of ixoberogene soroparvovec in neovascular age-related macular degeneration in the United States (OPTIC): a prospective, two-year, multicentre phase 1 study

Background

Gene therapy, successfully used in rare, monogenetic disorders, may prove to be a durable management approach for common, polygenetic conditions, including neovascular age-related macular degeneration (nAMD). Repeated injections, oftentimes monthly, and possibly for decades, of vascular endothelial growth factor antagonists (anti-VEGF), is the standard for nAMD. We hypothesised that an in-office, intravitreal administration of ixoberogene soroparvovec (ixo-vec, formerly ADVM-022), a single-dose gene therapy encoding for the proven anti-VEGF protein, aflibercept, would transform retinal cells to continually produce aflibercept to minimise treatment burden in nAMD.

Methods

In this two-year, open-label, prospective, multicentre phase 1 study, patients with nAMD responding to anti-VEGF were assigned to four cohorts differing by ixo-vec dose (2 × 1011 vs 6 × 1011 vector genomes (vg/eye)) and prophylactic steroids (oral prednisone vs topical difluprednate). The primary outcome was the type, severity, and incidence of ocular and systemic adverse events (AEs); secondary endpoints included vision, central subfield thickness (CST), and the number of supplemental injections. This study was registered with ClinicalTrials.gov, NCT03748784.

Findings

Thirty patients with nAMD were enrolled between November 14, 2018 and June 30, 2020 at nine study sites in the United States. No systemic ixo-vec related AEs were noted. Across both dose groups the most common adverse event was anterior chamber cell, which was reported in 11 participants in the 6 × 1011 dose group and in 7 participants in the 2 × 1011 dose group; intraocular inflammation was responsive to topical corticosteroids, with no anterior chamber cells or vitreous cells observed in 2 × 1011 vg/eye patients at the end of the study. Vision and CST remained stable throughout two years with annualised anti-VEGF injections reduced by 80% (10.0 mean annualised anti-VEGF injections to 1.9) in 2 × 1011 vg/eye and 98% (9.8 mean annualised anti-VEGF injections to 0.2) in 6 × 1011 vg/eye cohorts.

Interpretation

Ixo-vec was generally well-tolerated, maintained vision, and improved anatomical outcomes in nAMD, with a substantial reduction in anti-VEGF injections. A single administration of an in-office gene therapy, with vectorised protein with an already established clinical benefit, has the potential to revolutionise the management of common ocular disorders requiring ongoing, frequent therapeutic interventions.

Funding

Adverum Biotechnologies.

The ideal treatment timing for diabetic retinopathy: the molecular pathological mechanisms underlying early-stage diabetic retinopathy are a matter of concern

Diabetic retinopathy (DR) is a prevalent complication of diabetes, significantly impacting patients' quality of life due to vision loss. No pharmacological therapies are currently approved for DR, excepted the drugs to treat diabetic macular edema such as the anti-VEGF agents or steroids administered by intraocular route. Advancements in research have highlighted the crucial role of early intervention in DR for halting or delaying disease progression. This holds immense significance in enhancing patients' quality of life and alleviating the societal burden associated with medical care costs. The non-proliferative stage represents the early phase of DR. In comparison to the proliferative stage, pathological changes primarily manifest as microangiomas and hemorrhages, while at the cellular level, there is a loss of pericytes, neuronal cell death, and disruption of components and functionality within the retinal neuronal vascular unit encompassing pericytes and neurons. Both neurodegenerative and microvascular abnormalities manifest in the early stages of DR. Therefore, our focus lies on the non-proliferative stage of DR and we have initially summarized the mechanisms involved in its development, including pathways such as polyols, that revolve around the pathological changes occurring during this early stage. We also integrate cutting-edge mechanisms, including leukocyte adhesion, neutrophil extracellular traps, multiple RNA regulation, microorganisms, cell death (ferroptosis and pyroptosis), and other related mechanisms. The current status of drug therapy for early-stage DR is also discussed to provide insights for the development of pharmaceutical interventions targeting the early treatment of DR.

Lentiviral delivered aflibercept OXB-203 for treatment of neovascular AMD

Neovascular age-related macular degeneration (nAMD) is a leading cause of blindness in the aging population, with vascular endothelial growth factor (VEGF) playing a key role. Treatment with recombinant anti-VEGFs is the current standard of care; however, it is only effective for 1-2 months at a time and requires re-administration. Gene therapy could pave the way for stable, long-term expression of therapeutic anti-VEGF with a single dose, reducing the frequency of treatment and potentially improving clinical outcomes. As such, we have developed OXB-203, a lentiviral-based gene therapy encoding the anti-VEGF protein aflibercept. Aflibercept derived from OXB-203 exhibited comparable in vitro binding characteristics to VEGF as recombinant aflibercept. Furthermore, its biological potency was demonstrated by the equivalent inhibition of VEGF-induced human umbilical vein endothelial cell (HUVEC) proliferation and tubule formation as recombinant aflibercept. In a rat choroidal neovascularization (CNV) model of nAMD, a single subretinal administration of OXB-203 reduced laser-induced CNV lesion areas analogous to an intravitreal bolus of recombinant aflibercept. Finally, in a head-to-head comparative study, aflibercept derived from OXB-203 was shown to be expressed at significantly higher levels in ocular tissues than from an AAV8-aflibercept vector following a single subretinal delivery to rats. These findings support the therapeutic potential of OXB-203 for the management of nAMD.

The Role of Laser Photocoagulation in Treating Diabetic Macular Edema in the Era of Intravitreal Drug Administration: A Descriptive Review

Background and Objectives: This study aimed to elucidate the role of laser photocoagulation therapy in the treatment of diabetic macular edema (DME) as an alternative to, or in conjunction with, the first-line treatment, anti-vascular endothelial growth factor (VEGF). Materials and Methods: A comprehensive literature search to identify studies that evaluated the efficacy of laser photocoagulation therapy in the management of DME was performed. The relevant findings of the efficacy of focal/grid laser therapy from data in randomized, controlled trials were synthesized, and the potential of new laser technologies, such as navigated laser systems, pattern scan lasers, and subthreshold lasers, was explored. The usefulness of multimodal imaging-guided laser therapy was also evaluated, with a focus on the potential contribution to anti-VEGF therapy. Results: Focal laser photocoagulation targeting microaneurysms remains an effective therapeutic approach to chronic refractory edema, despite the widespread use of anti-VEGF therapy. To achieve the best possible treatment outcomes, precise identification of microaneurysms is essential. This requires the use of multimodal imaging-guided, highly accurate, minimally invasive coagulation techniques. Subthreshold laser therapy can also reduce the frequency of anti-VEGF injections and minimize treatment burden. Conclusions: Further studies are needed to determine the optimal timing and settings for laser photocoagulation therapy and the potential of new laser technologies in the management of DME. Nevertheless, laser photocoagulation therapy plays an important role in the management of DME, in conjunction with anti-VEGF therapy.

Anti-Scg3 Gene Therapy to Treat Choroidal Neovascularization in Mice

Neovascular age-related macular degeneration (nAMD) with choroidal neovascularization (CNV) is a leading cause of blindness in the elderly in developed countries. The disease is currently treated with anti-angiogenic biologics, including aflibercept, against vascular endothelial growth factor (VEGF) but with limited efficacy, treatment resistance and requirement for frequent intravitreal injections. Although anti-VEGF gene therapy may provide sustained therapy that obviates multiple injections, the efficacy and side effects related to VEGF pathway targeting remain, and alternative strategies to block angiogenesis independently of VEGF are needed. We recently reported that secretogranin III (Scg3) induces only pathological angiogenesis through VEGF-independent pathways, and Scg3-neutralizing antibodies selectively inhibit pathological but not physiological angiogenesis in mouse proliferative retinopathy models. Anti-Scg3 antibodies synergize dose-dependently with VEGF inhibitors in a CNV model. Here, we report that an adeno-associated virus-8 (AAV8) vector expressing anti-Scg3 Fab ameliorated CNV with an efficacy similar to that of AAV-aflibercept in a mouse model. This study is the first to test an anti-angiogenic gene therapy protocol that selectively targets pathological angiogenesis via a VEGF-independent mechanism. The findings support further safety/efficacy studies of anti-Scg3 gene therapy as monotherapy or combined with anti-VEGF to treat nAMD.

Targeting angiogenesis in oncology, ophthalmology and beyond

Angiogenesis is an essential process in normal development and in adult physiology, but can be disrupted in numerous diseases. The concept of targeting angiogenesis for treating diseases was proposed more than 50 years ago, and the first two drugs targeting vascular endothelial growth factor (VEGF), bevacizumab and pegaptanib, were approved in 2004 for the treatment of cancer and neovascular ophthalmic diseases, respectively. Since then, nearly 20 years of clinical experience with anti-angiogenic drugs (AADs) have demonstrated the importance of this therapeutic modality for these disorders. However, there is a need to improve clinical outcomes by enhancing therapeutic efficacy, overcoming drug resistance, defining surrogate markers, combining with other drugs and developing the next generation of therapeutics. In this Review, we examine emerging new targets, the development of new drugs and challenging issues such as the mode of action of AADs and elucidating mechanisms underlying clinical benefits; we also discuss possible future directions of the field.

Emerging therapeutic strategies for unmet need in neovascular age-related macular degeneration

Neovascular age-related macular degeneration (nAMD) is a major cause of visual impairment and blindness. Anti-vascular endothelial growth factor (VEGF) agents, such as ranibizumab, bevacizumab, aflibercept, brolucizumab and faricimab have revolutionized the clinical management of nAMD. However, there remains an unmet clinical need for new and improved therapies for nAMD, since many patients do not respond optimally, may lose response over time or exhibit sub-optimal durability, impacting on real world effectiveness. Evidence is emerging that targeting VEGF-A alone, as most agents have done until recently, may be insufficient and agents that target multiple pathways (e.g., aflibercept, faricimab and others in development) may be more efficacious. This article reviews issues and limitations that have arisen from the use of existing anti-VEGF agents, and argues that the future may lie in multi-targeted therapies including alternative agents and modalities that target both the VEGF ligand/receptor system as well as other pathways.

Design and development of biodegradable POSS-PCL-Zeolite (β) nano-scaffold for potential applications in bone regeneration

Side effects caused by bone fractures and restrictions on bone regeneration impose an enormous economic burden on the health system of society. To overcome these limitations, tissue engineering and cell-based therapies have been proposed as alternatives to induce and promote bone healing. Still, bone regeneration disadvantages, such as limited and painful surgery, the risk of infection, nerve injury, bleeding, and function damage, have led investigators to find an alternative therapy. In some studies, bone stimulants have prompted scientists to design scaffolds with appropriate physical structure with the possibility of cell adhesion and proliferation, which plays an influential role in the regeneration and repair of bone tissue. PCL nanofiber is an absorbing candidate for the formulation of biocompatible scaffolds used in tissue engineering. To overcome these negative aspects, improve the properties of PCL nanofibers, and based on the biocompatibility and superior mechanical properties of POSS, Polyhedral Oligomeric Silsesquioxane-Polycaprolactone-Zeolite (POSS-PCL-Zeolite) nanocomposite electrospun nanofiber scaffolds were fabricated in the present study. Nanohybrids and nanofibers structures were characterized by FTIR, HNMR, XRD, SEM, EDX, and DSC techniques. We used cellular and molecular assays, including DCFH ROS detection system, gene expression (RUNX-2, Osteocalcin, Nrf2, BAX, VEGF gens), and apoptotic to demonstrate the biocompatibility and induce bone differentiation of formulated POSS-PCL-Zeolite scaffolds. The results showed the biodegradability of POSS-PCL-Zeolite Nano-scaffold and supported the nesting of mesenchymal stem cells (MSCs) and induced bone differentiation by POSS-PCL-Zeolite Nano-scaffold.

Treatment of chronic diabetic macular oedema with intravitreal fluocinolone acetonide implant; real-life analysis of outcomes during overall treatment period

PURPOSE

To assess the clinical efficacy of the fluocinolone acetonide (FA) intravitreal implant (Iluvien, Alimera Sciences) over a 12-month period in a population resistant to treatment with first-line anti-VEGF agents.

METHODS

This study is a retrospective cohort study assessing functional and anatomical outcomes in 13 eyes of 12 patients treated for diabetic macular oedema (DMO) with a single fluocinolone implant (FA) (Iluvien) under real-world conditions. The follow-up period includes the time of first intravitreal treatment (incl anti-VEGF or short-lasting steroids) given until 12 months post FA implant insertion. Primary outcomes were best corrected visual acuity (BCVA), measured using the modified Early Treatment Diabetic Retinopathy Study (ETDRS) grading scale, and central foveal thickness (CFT), measured using Topcon 3DOCT-2000 (Topcon Inc) SD-OCT imaging. Mean BCVA and CFT were measured before anti-VEGF treatment, after anti-VEGF treatment, at the time of Iluvien implant insertion, and 6 and 12 months after Iluvien implant insertion. The t-paired sample test was used to ascertain statistical significance of changes in comparison of two samples while the ANOVA analysis was used in comparison of three or more samples.

RESULTS

The baseline BCVA (SD) of the cohort prior to initiation of anti-VEGF treatment was 47.45 (12.27) ETDRS letters whilst the mean CFT (SD) was 579 (203) microns. Following completion of anti-VEGF therapy, the mean improvement in vision was 8.9 ETDRS letters (p = 0.1) whilst the mean reduction in CFT was 197 microns (p = 0.028). Mean BCVA (SD) at the time of insertion of the FA implant was 55.15 (11.16) ETDRS letters and mean (SD) CFT at time of insertion of the FA was 454.62 μm (109.51). Following the 12-month treatment period with the FA implant, BCVA (SD) was 62.15 (10.25) ETDRS letters (p = 0.0331) and the mean (SD) CFT was 404.36 μm (142.92), a change of -50.26 μm from baseline (p = 0.0369).

CONCLUSIONS

This study has shown that statistically significant improvements in BCVA and CFT can be achieved over a 12-month period with the Iluvien implant. The implant has been shown to be a safe option in the treatment of DMO and may have a role to play in achieving good functional and anatomical outcomes in DMO while also reducing the frequency of follow-up appointments required to maintain stable vision in the working-age population.

Neovascular Age-Related Macular Degeneration (nAMD): A Review of Emerging Treatment Options

Neovascular age-related macular degeneration (nAMD) is a common world-wide cause of visual loss. Intravitreal anti-vascular endothelial growth factor (anti-VEGF) agents are an effective means to treat nAMD and reduce its impact on vision compared to either sham treatment or photodynamic therapy. Currently, the approved anti-VEGF drugs include ranibizumab, aflibercept and brolucizumab. In addition, bevacizumab, used as an off-label drug, and has been shown to be effective in treating nAMD. While anti-VEGF agents are effective, its limitations include the requirement for frequent, often monthly injections, and the need for long-term treatment of nAMD. These present significant burdens on the healthcare system and on the patients. In addition, reviews of patients with nAMD treated with anti-VEGF have reported deterioration of vision over time with progression of geographic atrophy. These limitations are partly addressed by exploring different treatment regimens that reduce the frequency of treatments. Newer anti-VEGF drugs have been shown in Phase III clinical trials to have injection intervals as long as 12 or even 16 weeks for a proportion of patients. There is research on newer drugs that affect other pathways, such as the angiopoietin pathway, which may impact nAMD by extending the treatment interval and reducing the burden of treatment. Other measures include the use of sustained-release implants that release the drug regularly over a period of time, and can be refilled periodically, as well as hydrogel platforms that serve to release the drug. The use of biosimilars will also serve to reduce the cost of treatment for nAMD. A new frontier of gene therapy, primarily targeting genes involved in the transduction of retinal cells to produce anti-VEGF proteins intraocularly, also opens a new avenue of therapeutic approaches that can be used for treatment. This review paper will discuss both current treatment options and the newer treatments under development.

Review of gene therapies for age-related macular degeneration

Gene therapies aim to deliver a therapeutic payload to specified tissues with underlying protein deficiency. Since the 1990s, gene therapies have been explored as potential treatments for chronic conditions requiring lifetime care and medical management. Ocular gene therapies target a range of ocular disorders, but retinal diseases are of particular importance due to the prevalence of retinal disease and the current treatment burden of such diseases on affected patients, as well as the challenge of properly delivering these therapies to the target tissue. The purpose of this review is to provide an update on the most current data available for five different retinal gene therapies currently undergoing clinical trials for use against age-related macular degeneration (AMD) and the development of novel delivery routes for the administration of such therapies. Research has been performed and compiled from PubMed and the select authors of this manuscript on the treatment and effectiveness of five current retinal gene therapies: Luxturna, ADVM-022, RGX-314, GT-005, and HMR59. We present the available data of current clinical trials for the treatment of neovascular and dry age-related macular degeneration with different AAV-based gene therapies. We also present current research on the progress of developing novel routes of administration for ocular gene therapies. Retinal gene therapies offer the potential for life-changing treatment for chronic conditions like age-related macular degeneration with a single administration. In doing so, gene therapies change the landscape of treatment options for these chronic conditions for both patient and provider.

Disease progression pathways of wet AMD: opportunities for new target discovery

INTRODUCTION

Age-related macular degeneration (AMD) is the leading cause of irreversible blindness among people age 60 years or older in developed countries. Current standard-of-care anti-vascular endothelial growth factor (VEGF) therapy, which inhibits angiogenesis and vascular permeability, has been shown to stabilize choroidal neovascularization and increase visual acuity in neovascular AMD. However, therapeutic limitations of anti-VEGF therapy include limited durability with consequent need for frequent intravitreal injections, and a ceiling of efficacy. Current strategies under investigation include targeting VEGF-C and VEGF-D, integrins, tyrosine kinase receptors, and the Tie2/angiopoietin-2 pathway. A literature search was conducted through November 30, 2021 on PubMed, Medline, Google Scholar, and associated digital platforms with the following keywords: wet macular degeneration, age-related macular degeneration, therapy, VEGF-A, VEGF-C, VEGF-D, integrins, Tie2/Ang2, and tyrosine kinase inhibitors.

AREAS COVERED

The authors provide a comprehensive review of AMD disease pathways and mechanisms involved in wet AMD as well as novel targets for future therapies.

EXPERT OPINION

With novel targets and advancements in drug delivery, there is potential to address treatment burden and to improve outcomes for patients afflicted with neovascular AMD.

Anti-VEGF and Other Novel Therapies for Neovascular Age-Related Macular Degeneration: An Update

Age-related macular degeneration (AMD) is a leading cause of visual impairment and blindness in older adults. The prognosis for the neovascular type of advanced AMD improved with the introduction of biological drugs with antiangiogenic properties, beginning with off-label bevacizumab, which was first used intravitreally in 2006. These drugs target newly formed vessels that grow beneath the center of the retina, causing loss of central vision, and they can help to maintain or improve vision. Repeated intravitreal injections are needed to achieve prolonged inhibition of proangiogenic cytokines, primarily vascular endothelial growth factor (VEGF). Major regulatory agencies have approved several molecules for AMD treatment, including ranibizumab, aflibercept, and brolucizumab. The development of further drugs was mainly targeted at prolonging anti-VEGF inhibition-thus reducing the frequency of injections-and expanding the biological targets of proangiogenic cytokine inhibition. Finally, biosimilars are already being marketed in some countries, allowing the containment of costs of AMD treatment, which are growing steadily in many settings because of the need for long-term treatment. This review summarizes the properties and clinical profiles of anti-VEGF biological drugs that are approved to treat neovascular AMD as well as ongoing research on molecules that may be marketed in the near future.

Hsp90-associated DNA replication checkpoint protein and proteasome-subunit components are involved in the age-related macular degeneration

Background:

Age-related macular degeneration (AMD) is the leading cause of vision loss worldwide. However, the mechanisms involved in the development and progression of AMD are poorly delineated. We aimed to explore the critical genes involved in the progression of AMD.

Methods:

The differentially expressed genes (DEGs) in AMD retinal pigment epithelial (RPE)/choroid tissues were identified using the microarray datasets GSE99248 and GSE125564, which were downloaded from the gene expression omnibus database. The overlapping DEGs from the two datasets were screened to identify DEG-related biological pathways using gene ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses. The hub genes were identified from these DEGs through protein-protein interaction network analyses. The expression levels of hub genes were evaluated by quantitative real-time polymerase chain reaction following the induction of senescence in ARPE-19 with FK866. Following the identification of AMD-related key genes, the potential small molecule compounds targeting the key genes were predicted by PharmacoDB. Finally, a microRNA-gene interaction network was constructed.

Results:

Microarray analyses identified 174 DEGs in the AMD RPE compared to the healthy RPE samples. These DEGs were primarily enriched in the pathways involved in the regulation of DNA replication, cell cycle, and proteasome-mediated protein polyubiquitination. Among the top ten hub genes, HSP90AA1, CHEK1, PSMA4, PSMD4, and PSMD8 were upregulated in the senescent ARPE-19 cells. Additionally, the drugs targeting HSP90AA1, CHEK1, and PSMA4 were identified. We hypothesize that Hsa-miR-16-5p might target four out of the five key DEGs in the AMD RPE.

Conclusions:

Based on our findings, HSP90AA1 is likely to be a central gene controlling the DNA replication and proteasome-mediated polyubiquitination during the RPE senescence observed in the progression of AMD. Targeting HSP90AA1, CHEK1, PSMA4, PSMD4, and/or PSMD8 genes through specific miRNAs or small molecules might potentially alleviate the progression of AMD through attenuating RPE senescence.