In vivo characterization of RC28-E, a fusion protein targeting VEGF and bFGF: Pharmacokinetics and ocular distribution in primates

Simultaneous inhibition of fibroblast growth factor-2 and vascular endothelial growth factor-a with RC28-E in diabetic macular edema: a phase 2 randomised trial

OBJECTIVE

To compare different doses and dosing regimens of RC28-E, a novel bispecific antibody that simultaneously binds vascular endothelial growth factor-A (VEGF-A) and fibroblast growth factor-2 (FGF-2), with conbercept in patients with diabetic macular edema (DME).

DESIGN

Prospective, randomised, active comparator-controlled, open-label, multicentre, phase 2 clinical trial.cente PARTICIPANTS: The trial enrolled patients aged 18 years or older with centre-involving DME, best-corrected visual acuity (BCVA) of 73 to 24 Early Treatment Diabetic Retinopathy Study (ETDRS) letters, and central subfield thickness (CST) of 300 µm or more.

METHODS

Patients were assigned randomly to one of five treatment regimens: 1.0 mg RC28-E for three initial monthly doses and then every 8 weeks (1.0mgQ8); 1.0 mg RC28-E for five initial monthly doses and then on a pro re nata (PRN) basis (1.0mgPRN); 2.0 mg RC28-E for three initial monthly doses and then every 8 weeks (2.0mgQ8); 2.0 mg RC28-E for five initial monthly doses and then on a PRN basis (2.0mgPRN); or 0.5 mg conbercept for three initial monthly doses and then on a PRN basis. Assessments were made at baseline and every 4 weeks thereafter.

MAIN OUTCOME MEASURES

The primary endpoint was the change in BCVA compared with baseline at 24 and 52 weeks. Secondary endpoints included the change in CST from baseline at 52 weeks; the proportion of patients who gained/lost ≥15 letters, ≥10 letters and >0 letter in BCVA; and the number of injections and safety outcomes.

RESULTS

The trial enrolled 156 patients. Mean improvements in BCVA in the RC28-E groups at week 24 were 7.1, 11.0, 7.4 and 10.5 letters for 1.0mgQ8, 1.0mgPRN, 2.0mgQ8 and 2.0mgPRN regimens, respectively, versus 9.7 letters for the conbercept group (p=0.146). By week 52, the RC28-E groups exhibited respective mean BCVA enhancements of 5.5, 9.5, 9.2 and 9.7 letters, compared with 8.4 letters of the conbercept group (p=0.469). Mean reductions in CST in the RC28-E groups at week 52 were -163.2 µm, -136.9 µm, -142.5 µm and -153.6 µm, versus -160.7 µm for the conbercept group (p=0.948). The Per Protocol Set analysis indicated that at 24 weeks, the BCVA improvement in the 2.0mgPRN group was significantly greater than that in the conbercept group (14.0 vs 9.8, p=0.019). In patients with poor baseline glycaemic control (HbA1c ≥7.5%), the 2.0mgPRN group showed greater BCVA improvement than the conbercept group (14.4 vs 4.2, p=0.039) at week 52. During the maintenance phase, the 2.0mgPRN group had fewer injections (2.8, 95% CI 1.8 to 3.7) compared with the conbercept group (4.4, 95% CI 3.5 to 5.2). RC28-E was generally well tolerated. The incidence of ocular adverse events in study eyes was comparable between RC28-E groups (22.6% in 1.0mgQ8 group, 26.7% in 1.0mgPRN group, 34.4% in 2.0mgQ8 group, 25.0% in 2.0 mg PRN group) and conbercept group (32.3%). The number of ocular serious adverse events was 1 (1.0mgQ8), 0 (1.0mgPRN), 1 (2.0mgQ8), 2 (2.0mgPRN) and 0 (conbercept).

CONCLUSIONS

Intravitreous RC28-E improved BCVA and CST in eyes with centre-involved DME. Compared with conbercept, the 2.0mgPRN regimen of RC28-E was recommended due to its superior efficacy in improving vision particularly for patients with poor glycaemic control, fewer treatment injections during the maintenance phase and comparable safety profile.

TRIAL REGISTRATION NUMBER

NCT04782115.

Safety and Efficacy of Multiple Escalating Doses of RC28-E for Neovascular Age-Related Macular Degeneration: A Phase 1b Trial

INTRODUCTION

To assess the safety and efficacy of repeated intravitreal injections of RC28-E, a novel bispecific antibody that simultaneously binds vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in patients with neovascular age-related macular degeneration (AMD). This was a prospective, multicenter, open-label clinical trial; 37 patients with choroidal neovascularization secondary to AMD and best-corrected visual acuity (BCVA) letter scores between 73 and 34 were enrolled.

METHODS

Treatment regimens consisted of a 3-month loading phase and a pro re nata (PRN) maintenance phase. This study included three treatment groups: the 0.5, 1.0, and 2.0 mg RC28-E groups, with escalating doses ranging from 0.5 to 2.0 mg. Patients were evaluated monthly for 48 weeks. Safety was assessed based on ocular and systemic adverse events (AEs), pharmacokinetic characteristics, and the presence of anti-RC28-E antibodies. Efficacy was assessed using the mean change in BCVA and central subfield thickness (CST) from baseline to week 48.

RESULTS

Most AEs were mild or moderate. The most common AE was a minor injection-related subconjunctival hemorrhage (16.2%). The AEs did not increase with dose or repeated injections. At week 48, mean improvements in BCVA from baseline in the 0.5, 1.0, and 2.0 mg groups were 6.1 ± 8.3, 9.9 ± 10.7, and 7.6 ± 9.38 letters, respectively; mean reductions in CST in the three groups were 112.1 ± 160.5, 175.1 ± 212.4, and 128.7 ± 145.8 μm, respectively. The serum RC28-E concentrations in 95% of the patients were below the quantification limit of the assay. No significant change from baseline was observed in the mean plasma concentrations of VEGF or FGF over the 48 weeks of treatment. Pre-treatment antibodies to RC28-E were detected in 1 of the 37 patients. Antibodies to RC28-E were detected in two patients after dosing with RC28-E for 48 weeks.

CONCLUSION

RC28-E was well tolerated and exhibited an overall favorable safety profile with evidence of improvements in BCVA and anatomical parameters.

Innovative Nanotechnology in Drug Delivery Systems for Advanced Treatment of Posterior Segment Ocular Diseases

Funduscopic diseases, including diabetic retinopathy (DR) and age-related macular degeneration (AMD), significantly impact global visual health, leading to impaired vision and irreversible blindness. Delivering drugs to the posterior segment of the eye remains a challenge due to the presence of multiple physiological and anatomical barriers. Conventional drug delivery methods often prove ineffective and may cause side effects. Nanomaterials, characterized by their small size, large surface area, tunable properties, and biocompatibility, enhance the permeability, stability, and targeting of drugs. Ocular nanomaterials encompass a wide range, including lipid nanomaterials, polymer nanomaterials, metal nanomaterials, carbon nanomaterials, quantum dot nanomaterials, and so on. These innovative materials, often combined with hydrogels and exosomes, are engineered to address multiple mechanisms, including macrophage polarization, reactive oxygen species (ROS) scavenging, and anti-vascular endothelial growth factor (VEGF). Compared to conventional modalities, nanomedicines achieve regulated and sustained delivery, reduced administration frequency, prolonged drug action, and minimized side effects. This study delves into the obstacles encountered in drug delivery to the posterior segment and highlights the progress facilitated by nanomedicine. Prospectively, these findings pave the way for next-generation ocular drug delivery systems and deeper clinical research, aiming to refine treatments, alleviate the burden on patients, and ultimately improve visual health globally.

Rethinking the potential and necessity of drug delivery systems in neovascular age-related macular degeneration therapy

Age-related macular degeneration (AMD) is the predominant threat to human vision and ultimately results in blindness. With the increase in the aging population, it has become a more crucial issue to human health. AMD is a multifactorial disease with the unique feature of uncontrollable angiogenesis during initiation and progression. Although increasing evidence indicates that AMD is largely hereditary, the predominant efficient treatment is antiangiogenesis, which mainly involves VEGF and HIF-α as therapeutic targets. The repeated administration of this treatment over the long term, generally through intravitreal injection, has called for the introduction of long-term drug delivery systems, which are expected to be achieved by biomaterials. However, the clinical results of the port delivery system indicate that the optimization of medical devices toward prolonging the activities of therapeutic biologics in AMD therapy seems more promising. These results indicate that we should rethink the possibility and potential of biomaterials as drug delivery systems in achieving long-term, sustained inhibition of angiogenesis in AMD therapy. In this review, the etiology, categorization, risk factors, pathogenesis, and current clinical treatments of AMD are briefly introduced. Next, the development status of long-term drug delivery systems is discussed, and the drawbacks and shortages of these systems are emphasized. By comprehensively considering the pathological aspect and the recent application of drug delivery systems in AMD therapy, we hope to find a better solution for the further development of long-term therapeutic strategies for AMD.

Changes in the vitreous body after experimental vitreous hemorrhage in rabbit: An interdisciplinary study

PURPOSE

To explore the changes in vitreous body after vitreous hemorrhage and assess its prognosis from the perspective of vitreoretinal interface.

METHODS

The experiment was performed on 32 New Zealand rabbits (64 eyes), weighing 2500-3000 g for 4 months and unlimited gender, which was injected with 0.2 mL of autologous blood into the center of vitreous cavity-the study group (right eyes), and the control one was treated in the same manner with equal volumes of saline. The rabbits were randomly and equally divided into the following four batches according to the days of observation: Days 3, 7, 14, and 30 after injection. IOP and severity grading were evaluated before rabbits' execution and eyeballs were enucleated. The anterior segment was separated to flow out the vitreous body naturally to detect the liquefaction degree and viscosity. Then, chemical composition of electrolytes, PCT and bFGF were determined by colorimetry and enzyme-linked immunosorbent assay (ELISA). Finally, the incidence of posterior vitreous detachment (PVD) was observed after vitreous sampled. The studies were double-blind.

RESULTS

After injection, the extent of vitreous opacity and coagulum size decreased over time. Both the degree of liquefaction and the length of tow differed significantly between two groups at different time points (all p < 0.001). The liquefaction degree in the study group rose obviously from the Day 14, which the viscosity declined significantly on the initial time. Biochemical markers fluctuated temporarily, except for basic fibroblast growth factor (bFGF), which continued to rise and was correlated with the liquefaction degree (r = 0.658, p < 0.001). Besides, the incidence of PVD increased from the 14th day (p < 0.05), and it was highly positively correlated with the number of macrophages (r = 0.934; p < 0.001).

CONCLUSION

After vitreous hemorrhage, the changes of the vitreous body are relatively minor earlier (2-4 weeks), but irreversible later. Specifically, the degree of liquefaction increases with a decrease in viscosity, and the chemotaxis of macrophages and bFGF induce incomplete PVD.

Neuroinflammation and neovascularization in diabetic eye diseases (DEDs): identification of potential pharmacotherapeutic targets

The goal of this review is to increase public knowledge of the etiopathogenesis of diabetic eye diseases (DEDs), such as diabetic retinopathy (DR) and ocular angiosarcoma (ASO), and the likelihood of blindness among elderly widows. A widow's life in North India, in general, is fraught with peril because of the economic and social isolation it brings, as well as the increased risk of death from heart disease, hypertension, diabetes, depression, and dementia. Neovascularization, neuroinflammation, and edema in the ocular tissue are hallmarks of the ASO, a rare form of malignant tumor. When diabetes, hypertension, and aging all contribute to increased oxidative stress, the DR can proceed to ASO. Microglia in the retina of the optic nerve head are responsible for causing inflammation, discomfort, and neurodegeneration. Those that come into contact with them will get blind as a result of this. Advanced glycation end products (AGE), vascular endothelial growth factor (VEGF), protein kinase C (PKC), poly-ADP-ribose polymerase (PARP), metalloproteinase9 (MMP9), nuclear factor kappaB (NFkB), program death ligand1 (PDL-1), factor VIII (FVIII), and von Willebrand factor (VWF) are potent agents for ocular neovascularisation (ONV), neuroinflammation and edema in the ocular tissue. AGE/VEGF, DAG/PKC, PARP/NFkB, RAS/VEGF, PDL-1/PD-1, VWF/FVIII/VEGF, and RAS/VEGF are all linked to the pathophysiology of DEDs. The interaction between ONV and ASO is mostly determined by the VWF/FVIII/VEGF and PDL-1/PD-1 axis. This study focused on retinoprotective medications that can pass the blood-retinal barrier and cure DEDs, as well as the factors that influence the etiology of neovascularization and neuroinflammation in the eye.

Microvolume Analysis of Aflibercept in Aqueous Humor Using Mass Spectrometry

Purpose

To develop a microvolume analytical method for measurement of the aflibercept concentration in human intraocular fluid and plasma.

Methods

We analyzed trace amounts of aflibercept in human aqueous humor using Fab-selective proteolysis and nano-surface and molecular-orientation limited (nSMOL) proteolysis, coupled with liquid chromatography–tandem mass spectrometry (LC-MS/MS). Patients with age-related macular degeneration or diabetic macular edema were recruited. Just after an injection of 50 µL of aflibercept, regurgitate from needle holes was collected with a micropipette pressed to the side of the injection hole within 10 seconds. The median amount of regurgitate was 4 µL (range, 1–18 µL).

Results

In human plasma, the aflibercept concentration ranged between 0.195 and 50 µg/mL when using the quantitative signature peptide IIWDSR (aa. 56–61) present on the vascular endothelial growth factor receptor 1 domain of aflibercept. The method was validated by evaluating its linearity, carryover, selectivity, accuracy and precision, dilution effect, and sample/processing stability. As only a minimal amount of regurgitate through needle holes can be sampled, we performed and verified the aflibercept assay using patient samples after 1:10 dilution with control human plasma, a recognized diluent. The median concentration of aflibercept in the regurgitate was 240 µg/mL (range, 13–4300 µg/mL).

Conclusions

Our findings indicate that the aflibercept assay using human intraocular fluid can be reliably performed using nSMOL coupled with LC-MS/MS.

Translational Relevance

This technique for quantifying aflibercept in the regurgitate suggests that the amount of drug lost post-injection can be ignored, even in patients with a relatively large leak after vitreous injection. This new methodology suggests possible therapeutic responses and may be employed as a general analytical method for trapping many biologics, such as vascular endothelial growth factor, in various types of clinical samples, unaffected by proteinaceous or small organic pharmaceuticals.

Biological drug therapy for ocular angiogenesis: Anti-VEGF agents and novel strategies based on nanotechnology

Currently, biological drug therapy for ocular angiogenesis treatment is based on the administration of anti‐VEGF agents via intravitreal route. The molecules approved with this purpose for ocular use include pegaptanib, ranibizumab, and aflibercept, whereas bevacizumab is commonly off‐label used in the clinical practice. The schedule dosage involves repeated intravitreal injections of anti‐VEGF agents to achieve and maintain effective concentrations in retina and choroids, which are administrated as solutions form. In this review article, we describe the features of different anti‐VEGF agents, major challenges for their ocular delivery and the nanoparticles in development as delivery system of them. In this way, several polymeric and lipid nanoparticles are explored to load anti‐VEGF agents with the aim of achieving sustained drug release and thus, minimize the number of intravitreal injections required. The main challenges were focused in the loading the molecules that maintain their bioactivity after their release from nanoparticulate system, followed the evaluation of them through studies of formulation stability, pharmacokinetic, and efficacy in in vitro and in vivo models. The analysis was based on the information published in peer‐reviewed published papers relevant to anti‐VEGF treatments and nanoparticles developed as ocular anti‐VEGF delivery system.