Vascular Endothelial Growth Factor Antagonists: Promising Players in the Treatment of Neovascular Age-Related Macular Degeneration

Neovascular age-related macular degeneration (nAMD) treatment has been revolutionized by the introduction of vascular endothelial growth factor antagonists (anti-VEGF), but the need for frequent intravitreal injections poses a heavy burden to patients and physicians. Evolving anti-VEGF therapies include longer duration agents, approaches that target multiple pathways, topical anti-VEGF agents, sustained-release, and genetic therapies. Abicipar pegol, a designed ankyrin repeat protein (DARPin), demonstrated the ability to maintain stable visual acuity with 12-week dosing, but was not approved by the FDA due to higher than usual rates of intraocular inflammation. Conbercept, a recombinant anti-VEGF fusion protein, has been approved in China, and is in Phase 3 trials globally. KSI-301 is an anti-VEGF antibody biopolymer conjugate that allowed 66% of nAMD patients to maintain at least a 6-month treatment-free interval in Phase 1b studies. OPT-302, an inhibitor of VEGF-C/D, will be tested in phase 3 studies that compare anti-VEGF-A monotherapy against combination therapy with OPT-302. Faricimab is a bispecific anti-VEGF/Ang-2 antibody that upregulates the Tie-2 signaling pathway and promotes vascular stability; it is undergoing phase 3 trials with potential for 12- or 16-week dosing. PAN-90806 is a topical anti-VEGF agent that showed the ability to reduce injection frequency by 79% compared to ranibizumab monotherapy in a phase 1/2a trial. Sustained-release anti-VEGF therapies include the ranibizumab Port Delivery System (in phase 3 studies), GB-102 (Phase 2b), OTX-TKI (phase 1), and Durasert (preclinical). Suprachoroidal delivery of the tyrosine kinase inhibitor, axitinib, is in preclinical studies. Genetic therapies in phase 1 studies include RGX-314 and ADVM-022, which introduce a viral vector that modifies the retina's cellular apparatus to create an anti-VEGF biofactory, potentially serving as a one-time treatment. Further investigation is warranted for drugs and delivery systems that hope to advance visual outcomes and reduce treatment burden of nAMD.

Current and Future Anti-VEGF Agents for Neovascular Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is the most common cause of legal blindness in developed countries. Neovascular (ie, wet) AMD is currently managed with intravitreal therapy. Traditional treatments (ie, bevacizumab, ranibizumab, aflibercept) provide high-efficacy therapy but can also require frequent dosing. Newer and future anti-VEGF therapies aim to decrease injection frequency through eitherlonger half life or port-delivery systems (brolucizumab, conbercept, KSI-301, ranibizumab). This review outlines current anti-VEGF treatments and ways by which their duration might be extended.

KSI-301: antibody biopolymer conjugate in retinal disorders

KSI-301 is a new intravitreal anti-vascular endothelial growth factor (VEGF) antibody biopolymer conjugate under investigation for the treatment of age-related macular degeneration (AMD), diabetic macular oedema (DME) and retinal vein occlusion (RVO). Preclinical and early clinical trials so far have shown promising results in retinal vascular diseases. When using anti-VEGF agents for treatment of retinal disorders, the frequency of injections and follow-up visits has increased the treatment burden, greatly affecting the treatment outcome. There are new anti-VEGF agents in the horizon with extended duration of action, durability, safety profile and efficacy, which seem to address the above issues. PubMed search and Medline search were performed on newer anti-VEGF agents, KSI-301, antibody biopolymer conjugate in retina, KODIAK KSI-301, DAZZLE study, GLEAM study, GLIMMER study, GLOW study and BEACON study. This review article showcases the biophysical properties and ongoing trials related to KSI-301. Moreover, we discuss the efficacy and safety profile of KSI-301 on the basis of the results of available trials.

KSI-301: an investigational anti-VEGF biopolymer conjugate for retinal diseases

INTRODUCTION

KSI-301 is an intravitreal anti-vascular endothelial growth factor (VEGF) agent in clinical trials for the treatment of neovascular age-related macular degeneration (nAMD), diabetic retinopathy, diabetic macular edema (DME), and retinal vein occlusion (RVO). Its antibody-biopolymer conjugate structure is designed to decrease clearance from the eye and increase the duration of the effect.

AREAS COVERED

This article briefly discusses the impact and mechanisms of nAMD, DME, and RVO and evaluates currently approved anti-VEGF therapies. It progresses to examine a new agent, KSI-301 and the results from numerous clinical trials in these disease areas.

EXPERT OPINION

Despite varied results in the phase 2b/3 study for nAMD, there is potential for KSI-301 to serve as a durable therapy for VEGF-mediated retinal disorders. Ongoing phase 3 trials for nAMD, DME, and RVO will provide additional evidence on its efficacy, duration, and safety profiles.

Perspectives on the currently available pharmacotherapy for wet macular degeneration

INTRODUCTION

Wet age-related macular degeneration (w-AMD) is a leading cause of visual impairment globally, with its prevalence expected to rise alongside increasing life expectancy. The current standard treatment involves frequent intravitreal injections of anti-VEGF agents, which although revolutionary, pose significant burdens on both patients and healthcare services.

AREAS COVERED

This review explores current and emerging pharmaceutical treatments for w-AMD, focusing on their pharmacokinetics, pharmacodynamics, efficacy, and safety. Promising developments include extending treatment intervals with newer anti-VEGF agents like brolucizumab and faricimab, biosimilars offering cost-effective options, and exploring innovative drug delivery methods such as subretinal gene therapy. Combination therapies, gene therapies, and novel agents like KSI-301 and OPT-302 show potential for improving treatment outcomes and reducing treatment burden.

EXPERT OPINION

While current treatments for w-AMD have significantly advanced with the advent of anti-VEGF therapies, their limitations in terms of treatment burden and incomplete responses have spurred research into diverse alternative approaches. These innovative strategies offer hope for improving patient outcomes and reducing healthcare burdens, suggesting a promising future for w-AMD management.