Pharmacokinetics of a long-lasting anti-VEGF fusion protein in rabbit

Physiologically based pharmacokinetic models for systemic disposition of protein therapeutics in rabbits

Physiologically based pharmacokinetic (PBPK) modelling is an important tool to predict drug disposition in the body. Rabbits play a pivotal role as a highly valued small animal model, particularly in the field of ocular therapeutics, where they serve as a crucial link between preclinical research and clinical applications. In this context, we have developed PBPK models designed specifically for rabbits, with a focus on accurately predicting the pharmacokinetic profiles of protein therapeutics following intravenous administration. Our goal was to comprehend the influence of key physiological factors on systemic disposition of antibodies and their functional derivatives. For the development of the systemic PBPK models, rabbit physiological factors such as gene expression, body weight, neonatal fragment crystallizable receptor (FcRn) binding, target binding, target concentrations, and target turnover rate were meticulously considered. Additionally, key protein parameters, encompassing hydrodynamic radius, binding kinetic constants (KD, koff), internal degradation of the protein-target complex, and renal clearance, were represented in the models. Our final rabbit models demonstrated a robust correlation between predicted and observed serum concentration-time profiles after single intravenous administration in rabbits, covering IgG, Fab, F(ab)2, Fc, and Fc fusion proteins from various publications. These pharmacokinetic simulations offer a promising platform for translating preclinical findings to clinical settings. The presented rabbit intravenous PBPK models lay an important foundation for more specific applications of protein therapeutics in ocular drug development.

Treatment of neovascular age-related macular degeneration with anti-vascular endothelial growth factor drugs: progress from mechanisms to clinical applications

Neovascular age-related macular degeneration (nARMD) is an important cause of visual impairment and blindness in the elderly, with choroidal neovascularization in the macula as the main pathological feature. The onset of nARMD is closely related to factors including age, oxidative stress, and lipid metabolism. Vascular endothelial growth factor (VEGF) is an important factor contributing to nARMD as well as choroidal neovascularization and retinal leakage formation. At present, anti-VEGF therapy is the only treatment that improves vision and halts disease progression in most patients, making anti-VEGF drugs a landmark development for nARMD treatment. Although intravitreal injection of anti-VEGF drugs has become the first-line treatment for nARMD, this treatment has many shortcomings including repeated injections, poor or no response in some patients, and complications such as retinal fibrosis. As a result, several new anti-VEGF drugs are being developed. This review provides a discussion of these new anti-VEGF drugs for the treatment of nARMD.

Comparative efficacy of anti-vascular endothelial growth factor on diabetic macular edema diagnosed with different patterns of optical coherence tomography: A network meta-analysis

Intravitreal anti-vascular endothelial growth factor (anti-VEGF) injections have emerged as the most common therapeutic approach for the management of diabetic macular edema (DME). Despite their proven superiority over other interventions, there is a paucity of data regarding the relative effectiveness of anti-VEGF agents in treating DME diagnosed with different patterns of optical coherence tomography (OCT). In this regard, we conducted a systematic review and comparative analysis of the therapeutic efficacy of intravitreal bevacizumab, ranibizumab, aflibercept, and conbercept in the management of DME with diffuse retinal thickening (DRT), cystoid macular edema (CME), and serous retinal detachment (SRD) patterns identified using OCT. Our study encompassed a comprehensive search of PubMed, Embase, Web of Science, China National Knowledge Infrastructure (CNKI), and Wan Fang Data from their inception until January 25, 2023. The network meta-analysis involved the inclusion of 1606 patients from 20 retrospective studies with a moderate risk of bias but no evidence of publication bias. The DRT group had the highest increase in best-corrected visual acuity (BCVA) with anti-VEGF, while the SRD group had the greatest reduction in Central Macular Thickness (CMT). Furthermore, conbercept, ranibizumab, and bevacizumab, respectively, showed the best treatment outcomes for patients with DRT, CME, and SRD in terms of improvement in BCVA. And, conbercept exhibited the highest reduction in CMT in the DRT, CME, and SRD groups. In conclusion, our study highlights the efficacy of anti-VEGF agents in the management of DME and provides valuable insights into the selection of anti-VEGF agents tailored to the individual needs of patients.

Comparative study on the efficacy of Conbercept and Aflibercept in the treatment of neovascular age-related macular degeneration

This study compares the effectiveness of Conbercept and Aflibercept in treating neovascular age-related macular degeneration (nAMD). Conducted at the First Affiliated Hospital of Chongqing Medical University's Ophthalmology Department (May 2020-May 2023), this prospective study enrolled 159 nAMD patients. Participants were randomly divided into two groups: one receiving 0.5 mg Conbercept and the other 2 mg Aflibercept intravitreal injections. Over 12 months, the study, employing a Treat-and-Extend (T&E) regimen, assessed Best-Corrected Visual Acuity (BCVA), Central Retinal Thickness (CRT) changes and injection frequency. Of the 159 patients, 137 (149 eyes) completed the study. No significant age difference was found between the groups (P = 0.331). After 12 months, BCVA improved similarly in both groups (Conbercept: 52.8 ± 18.9, Aflibercept: 52.0 ± 19.7 letters; P = 0.820). CRT reduction was also comparable (Conbercept: 246.3 ± 82.8 µm, Aflibercept: 275.9 ± 114.3 µm; P = 0.079). Injection frequencies averaged 6.9 ± 0.7 (Conbercept) and 6.7 ± 0.7 (Aflibercept; P = 0.255). Subtype analysis revealed Type 1 MNV had higher baseline BCVA and lower CRT, with more frequent injections compared to other types. Both Conbercept and Aflibercept are clinically similar in efficacy for nAMD, with the T&E regimen proving therapeutically effective and potentially reducing patient costs. Anti-VEGF treatment efficacy varies across nAMD subtypes, indicating a potential benefit in tailored treatments for specific subtypes.Clinical trial registration number NCT05539235 (Protocol Registration and Results System).

Efficacy comparison of anti-vascular endothelial growth factor drugs for the treatment of type 1 retinopathy of prematurity: A network meta-analysis of randomised controlled trials

PURPOSE

To compare the efficacy of different anti-vascular endothelial growth factor (VEGF) agents for the treatment of retinopathy of prematurity (ROP) in preterm infants.

METHODS

Seven databases were searched for eligible literature up to February 22, 2023. Studies were included if they were randomised controlled trials (RCTs) investigating the efficacy of anti-VEGF agents for ROP in infants. A network meta-analysis (NMA) was performed. We also conducted subgroup analyses to determine the efficacy ranking of regimens used in different regions. The odds ratio (OR), standardised mean difference (SMD), and surface under the cumulative ranking curve (SUCRA) were calculated for each outcome.

RESULTS

Thirteen RCTs of 10 different regimens, involving 1196 infants (2388 eyes), were identified. Bevacizumab (0.625 mg; OR = 0.16, 95% confidence interval [CI] 0.06-0.40, SUCRA = 80.6%) and conbercept (0.15 mg; OR = 0.08, 95% CI 0.02-0.30, SUCRA = 96.0%) were the most effective regimens in reducing the risk of ROP recurrence requiring retreatment in Western countries and China, respectively. Compared with laser therapy, bevacizumab (0.625 mg; SMD = 1.54, 95% CI 0.06-3.02) achieved significantly longer intervals between treatment and recurrence. No significant difference in the risk of retinal detachment was detected between any anti-VEGF agent and laser (p > 0.05).

CONCLUSIONS

Bevacizumab (0.625 mg) and conbercept (0.15 mg) appeared to be the most effective therapies for ROP in Western countries and China, respectively. More high-quality RCTs are warranted to evaluate the efficacy and long-term safety of anti-VEGF drugs for the management of ROP.

A bioengineered anti-VEGF protein with high affinity and high concentration for intravitreal treatment of wet age-related macular degeneration

Intravitreal (IVT) injection of anti-vascular endothelial growth factor (anti-VEGF) has greatly improved the treatment of many retinal disorders, including wet age-related macular degeneration (wAMD), which is the third leading cause of blindness. However, frequent injections can be difficult for patients and may lead to various risks such as elevated intraocular pressure, infection, and retinal detachment. To address this issue, researchers have found that IVT injection of anti-VEGF proteins at their maximally viable concentration and dose can be an effective strategy. However, the intrinsic protein structure can limit the maximum concentration due to stability and solution viscosity. To overcome this challenge, we developed a novel anti-VEGF protein called nanoFc by fusing anti-VEGF nanobodies with a crystallizable fragment (Fc). NanoFc has demonstrated high binding affinity to VEGF165 through multivalency and potent bioactivity in various bioassays. Furthermore, nanoFc maintains satisfactory chemical and physical stability at 4°C over 1 month and is easily injectable at concentrations up to 200 mg/mL due to its unique architecture that yields a smaller shape factor. The design of nanoFc offers a bioengineering strategy to ensure both strong anti-VEGF binding affinity and high protein concentration, with the goal of reducing the frequency of IV injections.

Safety and efficacy of intravitreal injection of conbercept for the treatment of patients with choroidal neovascularization secondary to pathological myopia: Results from the SHINY study

PURPOSE

To evaluate the safety and efficacy of intravitreal injections of 0.5 mg conbercept in patients with choroidal neovascularization secondary to pathological myopia (pmCNV).

METHODS

The 177 pmCNV patients were randomly assigned in a 3:1 ratio to receive conbercept or sham injection, respectively. The conbercept group receive conbercept intravitreal injections administered on a pro re nata (PRN) basis after 3 monthly loading doses. The sham group received three consecutive monthly sham injections and then one conbercept injection followed by PRN conbercept intravitreal injections.

RESULTS

At month 3, the mean BCVA for the two groups were improved by 12.0 letters (conbercept group, from 54.05 letters to 66.05 letters) and 0.6 letters (sham group, from 49.77 letters to 50.33 letters), respectively (p < 0.001). The mean central retinal thickness (CRT) at month 3 in the two groups decreased 62.0 μm (conbercept group, from 348.90 μm to 286.18 μm) and 4.4 μm (sham group, from 347.86 μm to 343.47 μm) (p < 0.001). At month 9, the mean BCVA improved by 13.3 letters in the conbercept group and 11.3 letters in the sham group. The mean CRT decreased 73.6 μm in the conbercept group and 55.9 μm in the sham group (p < 0.001). The most common ocular adverse events were associated with intravitreal injections, such as conjunctival haemorrhage and increased intraocular pressure.

CONCLUSION

Intravitreal injections of 0.5 mg conbercept provided improvement in visual and anatomical outcomes in pmCNV patients with low rates of ocular and nonocular safety events.

Switching to Conbercept in Diabetic Macular Edema After Unsatisfactory Response to Previous Intravitreal Injection of Ranibizumab

Objective

To assess the functional and anatomical effects of transitioning to conbercept intravitreal injection (IVC) treatment in patients with diabetic macular edema (DME) who had inadequate responses to prior anti-vascular endothelial growth factor (anti-VEGF) injections.

Methods

We retrospectively included eyes with persistent DME after at least 3 injections of intravitreal ranibizumab (IVR). The analysis included the assessment of best corrected visual acuity (BCVA) and central macular thickness (CMT) during 6 months after the switch.

Results

A total of 30 patients (30 eyes) were included. CMT dropped sharply from 437.8±40.67μm at baseline to 363.59±45.09,312.52 ± 39.15, 278.51 ± 37.92, and 292.59 ± 38.09 after 1, 2, 3 and 6 months of IVC, respectively (p <0.001). BCVA in log MAR units was significantly improved from 0.73±0.15 at baseline to 0.50±0.09,0.46±0.72, 0.40±0.06 and 0.48±0.04 after 1, 2, 3 and 6 months, respectively (p <0.001).

Conclusion

Switching to Conbercept effectively improved visual and anatomical structure in DME patients who had not responded satisfactorily to previous anti-VEGF injections.

Preclinical evaluation of KH631, a novel rAAV8 gene therapy product for neovascular age-related macular degeneration

The upregulation of vascular endothelial growth factor (VEGF) is strongly associated with the development of choroidal neovascularization (CNV) in patients with neovascular age-related macular degeneration (nAMD). Currently, the standard treatment for nAMD involves frequent intravitreal injections of anti-VEGF agents, which inhibit the growth of new blood vessels and prevent leakage. However, this treatment regimen places a significant burden on patients, their families, and healthcare providers due to the need for repeated visits to the clinic for injections. Gene therapy, which enables the sustained expression of anti-VEGF proteins after a single injection, can dramatically reduce the treatment burden. KH631 is a recombinant adeno-associated virus 8 vector that encodes a human VEGF receptor fusion protein, and it is being developed as a long-term treatment for nAMD. In preclinical studies using non-human primates, subretinal administration of KH631 at a low dose of 3 × 108 vg/eye resulted in remarkable retention of the transgene product in the retina and prevented the formation and progression of grade IV CNV lesions. Furthermore, sustained transgene expression was observed for more than 96 weeks. These findings suggest that a single subretinal injection of KH631 has the potential to offer a one-time, low-dose treatment for nAMD patients.

Microinvasive pars plana vitrectomy combined with internal limiting membrane peeling versus anti-VEGF intravitreal injection for treatment-naïve diabetic macular edema (VVV-DME study): study protocol for a randomized controlled trial

BACKGROUND

Diabetic macular edema (DME) is the main cause of vision loss in diabetic patients. Currently, anti-vascular endothelial growth factor (VEGF) intravitreal injection stands as the first-line therapy for DME. However, some patients exhibit insufficient response to anti-VEGF agents and often require multiple injections, imposing psychological and economic burdens. While microinvasive pars plana vitrectomy (PPV) has been shown to be safe and effective in treating refractory DME, scant research has explored its application to treatment-naïve DME. The purpose of this study is to determine whether early PPV combined with internal limiting membrane (ILM) peeling can lessen the therapeutic burden of DME patients, prevent vision loss, and maintain long-term stabilization of diabetic retinopathy.

METHODS

This is a single-center, prospective, parallel-group, non-inferiority randomized controlled trial involving 102 DME participants. Participants will be randomly assigned to either the study group (PPV combined with ILM peeling) or the control group (conbercept intravitreal injection (IVC)) at a 1:1 ratio, with a scheduled follow-up at 12 months post-operation. Comparative analysis of results between the two groups will be conducted at months 1, 3, 6, and 12 after the intervention. The primary outcomes involve evaluating the changes in central subfield thickness (CST) and best corrected visual acuity (BCVA). The secondary outcomes include assessment of optical coherence tomography (OCT) and OCT angiography (OCTA) biomarkers, re-treatment and adverse events rates, diabetic retinopathy (DR) development, cost-effectiveness analysis, and vision-related quality of life (VRQL).

DISCUSSION

Some patients do not respond well to anti-VEGF drugs and repeated intravitreal injections increase the treatment burden for patients. The VVV study aims to explore whether PPV combined with ILM peeling could become an initial treatment option for treatment-naïve DME patients.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05728476. Registered on 15 February 2023.

Treatment of filtration bleb dysfunction after glaucoma surgery by needle revision of filtration bleb combined with conbercept

Filtration surgery (Trabeculectomy) is the main treatment for glaucoma. The scarring of the filtration bleb and obstruction of the outflow of aqueous humor through the filtration channel are the main reasons of the surgery failure. The objective of this study was to determine the clinical efficacy of needle revision of filtration blebs combined with subconjunctival injection of conbercept on the functional bleb formation in glaucoma patients with eye pressure out of control after trabeculectomy. A total of 48 eyes with poor filtration bleb function after trabeculectomy for glaucoma were treated with needle revision of filtration bleb combined with subconjunctival injection of conbercept. After the treatment, the patients were followed up for 3 months during which visual acuity, intraocular pressure, slit lamp and ultrasound biomicroscope examinations were performed. Intraoperative and postoperative complications were recorded. The visual acuity and intraocular pressure were significantly improved after the needle revision of filtration blebs. Among the 48 eyes, 39 eyes still had functional blebs at the end of the follow-up period, and filtration blebs failed in 9 eyes 2 to 8 weeks after the removal of the needle. The survival rate of filtration blebs at 3 months after needle revision was (79.06 ± 3.42%), and 81.25% (39/48) of the eyes showed good formation rate of functional bleb at the last follow-up. Three months after needle revision, there was local scar formation in some filtration blebs. Part of the filtration blebs showed mild thickening of the local subconjunctival tissue, and the filtration bleb was slightly raised and diffuse, showing a multi-cavity and thin-walled shape in some blebs. Ultrasound biomicroscopy examination showed relative structural manifestations. Subconjunctival hemorrhage occurred in 43 patients during and after the operation. Low intraocular pressure occurred in 8 patients with the lowest pressure of 5 mm Hg. Choroidal edema was observed in 3 patients. Five patients had intraoperative conjunctival hemorrhage in the anterior chamber, and hyphema occurred. All complications were self-limited and resolved without surgical intervention. Needle revision of filtration bleb combined with anti-VEGF drugs is a safe and effective method for the treatment of filtration bleb dysfunction after surgery of glaucoma.

Twenty Years of Anti-Vascular Endothelial Growth Factor Therapeutics in Neovascular Age-Related Macular Degeneration Treatment

Neovascular age-related macular degeneration (nAMD) is the primary disastrous retinal disease that leads to blindness in the elderly population. In the early 2000s, nAMD resulted in irreversible vision loss and blindness with no available treatment options. However, there have been breakthrough advances in the drug development of anti-angiogenic biological agents over the last two decades. The primary target molecule for treating nAMD is the vascular endothelial growth factor (VEGF), and there are currently several anti-VEGF drugs such as bevacizumab, ranibizumab, and aflibercept, which have made nAMD more manageable than before, thus preventing vision loss. Nevertheless, it should be noted that these anti-VEGF drugs for nAMD treatment are not effective in more than half of the patients, and even those who initially gain visual improvements lose their vision over time, along with potential deterioration in the geography of atrophy. As a result, there have been continuous endeavors to improve anti-VEGF agents through better efficacy, fewer doses, expanded intervals, and additional targets. This review describes past and current anti-VEGF therapeutics used to treat nAMD and outlines future directions to improve the effectiveness and safety of anti-VEGF agents.

Comparison of the adjuvant effect of conbercept intravitreal injection at different times before vitrectomy for proliferative diabetic retinopathy

Purpose

To assess the optimal time of intravitreal conbercept (IVC) treatment prior to pars plana vitrectomy (PPV) in patients with severe proliferative diabetic retinopathy (PDR).

Method

This study was exploratory in nature. Forty-eight consecutive patients (48 eyes) with PDR were divided into four groups according to different IVC times (0.5 mg/0.05 mL) before PPV: group A (3 days), group B (7 days), group C (14 days), and group D (non-IVC). Intraoperative and postoperative effectiveness were assessed, and vitreous VEGF concentrations were detected.

Result

For intraoperative effectiveness, groups A and D had a higher incidence of intraoperative bleeding than groups B and C (P = 0.041). Furthermore, groups A-C required less surgical time than group D (P < 0.05). For postoperative effectiveness, group B had a significantly higher proportion of visual acuity that improved or remained unchanged than group D (P = 0.014), and groups A-C had lower proportions of postoperative bleeding than group D. The vitreous VEGF concentration of group B (67.04 ± 47.24 pg/mL) was significantly lower than that of group D (178.29 ± 110.50 pg/mL) (P = 0.005).

Conclusion

IVC treatment that was administered 7 days preoperatively was associated with better effectiveness and a lower vitreous VEGF concentration than its administration at other time points.

Delivery Systems in Ocular Retinopathies: The Promising Future of Intravitreal Hydrogels as Sustained-Release Scaffolds

Slow-release delivery systems are needed to ensure long-term sustained treatments for retinal diseases such as age-related macular degeneration and diabetic retinopathy, which are currently treated with anti-angiogenic agents that require frequent intraocular injections. These can cause serious co-morbidities for the patients and are far from providing the adequate drug/protein release rates and required pharmacokinetics to sustain prolonged efficacy. This review focuses on the use of hydrogels, particularly on temperature-responsive hydrogels as delivery vehicles for the intravitreal injection of retinal therapies, their advantages and disadvantages for intraocular administration, and the current advances in their use to treat retinal diseases.

Effect of Adjunctive Intravitreal Conbercept Injection at the End of 25G Vitrectomy on Severe Proliferative Diabetic Retinopathy: 6-Month Outcomes of a Randomised Controlled Trial

INTRODUCTION

This study aimed to evaluate the effect of pre-operative versus pre-operative plus post-operative intravitreal conbercept (IVC) injection on severe proliferative diabetic retinopathy (PDR).

METHODS

This was a prospective, comparative and randomised study. A total of 84 patients who underwent vitrectomy for severe PDR were included in this study. Patients were randomly divided into control (41 eyes) and experiment (43 eyes) groups. Patients in the experiment group received adjunctive pre-operative and post-operative IVC injection, whereas patients in the control group only received pre-operative IVC injection. The incidence of post-operative vitreous haemorrhage (POVH), best-corrected visual acuity (BCVA) and central retinal thickness (CRT) were determined.

RESULTS

The incidence of early POVH was significantly different between the two groups, but no significant difference was observed between groups at 3 and 6 months. In the experiment group, the BCVA was significantly improved 1 month after surgery when compared with the control group (p 0.019). There was no marked difference in the mean post-operative BCVA at 3 and 6 months between groups (p 0.063 and 0.082). CRT was significantly lower in the experiment group than in the control group at 1 and 3 months after surgery (p 0.037 and 0.041), but there was no significant difference at 6 months (p 0.894).

CONCLUSION

Additional IVC injected at the end of surgery improves the POVH and BCVA at the early stage after surgery in severe PDR, but this benefit is absent at 6 months. Further studies are needed to investigate the effect of IVC at the end of vitrectomy.

TRIAL REGISTRATION

chictr.org.cn identifier: ChiCTR2200060735. Retrospectively registered, register date: 9 June 2022.

Intraocular delivery considerations of ocular biologic products and key preclinical determinations

INTRODUCTION

Ophthalmic diseases of the retina are a significant cause of vision loss globally. Despite much progress, there remains an unmet need for durable, long-acting treatment options. While biologic therapies show great promise, they present many challenges, including complexities in biochemical properties, mechanism of action, manufacturing considerations, preclinical evaluation, and delivery mechanism; these are confounded by the unique anatomy and physiology of the eye itself.

AREAS COVERED

This review describes the current development status of intravitreally administered drugs for the treatment of ophthalmic disease, outlines the range of approaches that can be considered for sustained drug delivery to the eye, and discusses key preclinical considerations for the evaluation of ocular biologics.

EXPERT OPINION

The required frequency of dosing in the eye results in a great burden on both patients and the health care system, with direct intraocular administration remaining the most reliable and predictable route. Sustained and controlled ophthalmic drug delivery systems will go a long way in reducing this burden. Sustained delivery can directly dose target tissues, improving bioavailability and reducing off-target systemic effects. Maintaining stability and activity of compounds can prevent aggregation and enable extended duration of release, while sustaining dosage and preventing residual polymer after drug depletion.

Intravitreal conbercept as an adjuvant in vitrectomy for proliferative diabetic retinopathy: a meta-analysis of randomised controlled trials

PURPOSE

To evaluate the efficacy of intravitreal conbercept (IVC) in pars plana vitrectomy (PPV) for patients with proliferative diabetic retinopathy (PDR).

METHODS

A meta-analysis of randomized control trials (RCTs) using online databases was performed. The intraoperative outcome measures were the incidence of intraoperative bleeding and endodiathermy application, and the mean surgical time. The postoperative outcome measures were mean change in best-corrected visual acuity (BCVA) from baseline, postoperative vitreous clear-up time and incidence of recurrent vitreous hemorrhage (VH).

RESULTS

Eight RCTs were selected for meta-analysis. They included 409 eyes (215 eyes in IVC group and 194 eyes in no conbercept group). Preoperative IVC application was associated with less intraoperative bleeding and endodiathermy applications (RR = 0.34, 95% CI, 0.23-0.50, P < 0.00001, and RR = 0.26, 95% CI, 0.12-0.56, P = 0.0005) compared to no conbercept. It also shortened surgical time (WMD = -15.87, 95% CI, -22.04 to -9.69, P < 0.00001). In addition, preoperative or intraoperative IVC achieved better BCVA outcome (WMD = -0.37, 95% CI, -0.62 to -0.13, P = 0.003), shorter vitreous clear-up time postoperatively (WMD = -5.44, 95% CI, -6.31 to -4.57, P < 0.00001) and a lower rate of VH recurrence (RR = 0.45, 95% CI, 0.22-0.91, P = 0.03).

CONCLUSION

IVC is an effective adjuvant in PPV for PDR, with better intraoperative and postoperative outcomes.

Predictors of anti-VEGF efficacy in chronic central serous chorioretinopathy based on intraocular cytokine levels and pigment epithelium detachment subtypes

PURPOSE

The aim of this study was to compare intraocular cytokines among different types of pigment epithelial detachments (PEDs) in patients with chronic central serous chorioretinopathy (CSC) and to investigate the association of cytokine levels and PED types with response to anti-vascular endothelial growth factor (VEGF) therapy.

METHODS

We included 88 patients with chronic CSC and 30 controls. The anti-VEGF agent conbercept was given intravitreally to chronic CSC patients. Cytokines VEGF, interleukin-6 (IL-6), IL-8, IL-10, interferon-inducible protein-10 and monocyte chemoattractant protein-1 in aqueous humour were measured. Treatment efficacy, cytokine levels, changes in best-corrected visual acuity (BCVA) and optical coherence tomography parameters were assessed at baseline and 1 month after treatment.

RESULTS

Patients were divided into three groups: flat irregular PED (FIPED) with choroidal neovascularization (CNV), FIPED without CNV and focal PED. Vascular endothelial growth factor (VEGF) was the only cytokine significantly higher in chronic CSC FIPED patients. There were no significant differences in VEGF between FIPED patients with or without CNV (p = 0.234). At 1 month after conbercept injection, treatment effective rates in FIPED patients with or without CNV were significantly higher than in patients with focal PED (p < 0.05). Best-corrected visual acuity (BCVA) was improved in both FIPED groups (p < 0.05), but not in the focal PED group (p = 0.180). All three groups had significant decreases in central macular thickness (p < 0.05), and PED heights in FIPED patients were reduced (p < 0.05).

CONCLUSIONS

Patients with FIPED in chronic CSC had elevated intraocular VEGF levels and responded favourably to conbercept. Anti-VEGF treatment may be an option for FIPED CSC patients with or without secondary CNV.

A Study on the Drug Concentration in Fellow Eyes After Unilateral Intravitreal Injection of Conbercept Into New Zealand Rabbit Eyes

Intravitreal injections of anti-vascular endothelial growth factor (VEGF) have become increasingly popular in the treatment of ocular diseases. However, few studies have determined the efficiency of unilateral intravitreal anti-VEGF injection in the fellow eye. Herein, we performed a study to investigate the drug concentration in fellow eyes and venous serum after unilateral intravitreal injection of conbercept into rabbit eyes. This is an experimental animal study. Thirty male New Zealand rabbits (60 eyes) were used. One eye of each rabbit was intravitreally injected with 0.5 mg of conbercept. Both eyes from six rabbits were enucleated on days 1, 3, 7, 14, and 30. Conbercept concentrations were measured in the serum, aqueous humor, and vitreous humor. We found conbercept was detected in the fellow eyes and serum of rabbits. Conbercept concentrations in the vitreous humor of the fellow eyes increased from 74.11 ng/ml on day 1 to 246.69 ng/ml on day 3 and then declined to 69.11 ng/ml after 30 days. The concentration in the aqueous humor peaked on day 1 with a concentration of 244.82 ng/ml and declined to 40.13 ng/ml after 30 days. The maximum conbercept concentrations in the aqueous humor and vitreous humor of fellow eyes were similar, which were 0.2 and 1.3% of those of the injected eye, respectively. A peak concentration of 102.49 ng/ml was achieved in the venous serum 1 day after intravitreal injection of conbercept, which was 0.08 and 0.5% of those of the maximum conbercept concentrations in the vitreous humor and aqueous humor of the injected eye, respectively, and 41.5 and 41.8% of the maximum conbercept concentrations in the vitreous humor and aqueous humor of the non-injected eye, respectively. In conclusion, after intravitreal injection of 0.5 mg of conbercept into rabbit eyes, very small amounts of conbercept were detected in the fellow non-injected eyes and venous serum.

[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.

Posterior Segment Ophthalmic Drug Delivery: Role of Muco-Adhesion with a Special Focus on Chitosan

Posterior segment eye diseases (PSEDs) including age macular degeneration (AMD) and diabetic retinopathy (DR) are amongst the major causes of irreversible blindness worldwide. Due to the numerous barriers encountered, highly invasive intravitreal (IVT) injections represent the primary route to deliver drugs to the posterior eye tissues. Thus, the potential of a more patient friendly topical route has been widely investigated. Mucoadhesive formulations can decrease precorneal clearance while prolonging precorneal residence. Thus, they are expected to enhance the chances of adherence to corneal and conjunctival surfaces and as such, enable increased delivery to the posterior eye segment. Among the mucoadhesive polymers available, chitosan is the most widely explored due to its outstanding mucoadhesive characteristics. In this review, the major PSEDs, their treatments, barriers to topical delivery, and routes of topical drug absorption to the posterior eye are presented. To enable the successful design of mucoadhesive ophthalmic drug delivery systems (DDSs), an overview of mucoadhesion, its theory, characterization, and considerations for ocular mucoadhesion is given. Furthermore, chitosan-based DDs that have been explored to promote topical drug delivery to the posterior eye segment are reviewed. Finally, challenges of successful preclinical to clinical translation of these DDSs for posterior eye drug delivery are discussed.

New and Innovative Treatments for Neovascular Age-Related Macular Degeneration (nAMD)

Age-related macular degeneration (AMD) is one of the most common causes of vision loss. Advanced forms of AMD are seen in primarily two types—neovascular AMD (nAMD) with the presence of choroid neovascularization and non-neovascular AMD (nnAMD) with geographic atrophy. Neovascular AMD is characterized by choroidal neovascularization (CNV), which leads to a cascade of complications, including exudation, leakage, and ultimately fibrosis with photoreceptor loss. Inhibition of VEGF represents the current standard of care. However, there is a tremendous gap between the outcomes in randomized clinical trials and real-world settings. New agents for nAMD might offer the potential to improve treatment outcomes and reduce treatment of frequent intravitreal injections. We summarize all the newer molecules, their pivotal clinical trial results, and their unique mechanisms of action; these include longer-acting agents, combination strategies, sustained release, and genetic therapies.

Intravitreal conbercept for diabetic macular oedema: 2-year results from a randomised controlled trial and open-label extension study

BACKGROUND

To demonstrate the efficacy and safety of intravitreal injections of conbercept versus laser photocoagulation in the treatment of diabetic macular oedema (DME).

METHODS

A 12-month multicentre, randomised, double-masked, double-sham, parallel controlled, phase III trial (Sailing Study), followed by a 12-month open-label extension study. Patients with centre-involved DME were randomly assigned to receive either laser photocoagulation followed by pro re nata (PRN) sham intravitreal injections (laser/sham) or sham laser photocoagulation followed by PRN 0.5 mg conbercept intravitreal injections (sham/conbercept). Patients who entered the extension study received PRN conbercept treatment. The primary endpoint was the changes in best-corrected visual acuity (BCVA) from baseline.

RESULTS

A total of 248 eyes were included in the full analysis set and 157 eyes continued in the extension study. Significant improvement in mean change in BCVA from baseline to month 12 was observed in the sham/conbercept group (8.2±9.5 letters), whereas no improvement was observed in the laser/sham group (0.3±12.0 letters). Patients in the laser/sham group showed a marked improvement in BCVA after the switch to conbercept in the extension study, and there was no difference in BCVA between the two groups at the end of the extension study.

CONCLUSION

The use of a conbercept PRN intravitreal injection regimen improved the BCVA of patients with DME, and its efficacy was better than that of laser photocoagulations, and the same efficacy was observed when the eyes treated with laser alone were switched to conbercept.

TRIAL REGISTRATION NUMBER

NCT02194634.

The Role of Intravitreal Anti-VEGF Agents in Rabbit Eye Model of Open-Globe Injury

Purpose

To evaluate the effects of intravitreal anti-VEGF agents in a rabbit model of open-globe injury (OGI).

Methods

OGI was induced in the right eyes of 75 Belgian rabbits by making 5 mm circumferential incision placed 6 mm behind the limbus. The rabbits were divided into 4 groups: control (n = 5), OGI group (n = 40), and intravitreal Ranibizumab and Conbercept (n = 15 each). Ranibizumab or Conbercept was injected into the vitreous at 0.5 hours, 3 days, or 7 days. Vitreous fluid was collected, and levels of growth factors and cytokines were measured by enzyme-linked immunosorbent assay (ELISA). On day 28 after OGI, B scan examination and histological examination were performed to evaluate intravitreal proliferation and formation of epiretinal fibrosis.

Results

Vitreous levels of vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), transforming growth factor-beta (TGF-β), and plasminogen activator inhibitor-1 (PAI-1) were significantly increased in rabbit eyes after OGI. Compared to eyes in OGI group, anti-VEGF treatments significantly reduced these growth factors and cytokines. Among the 7 eyes examined from each group for intravitreal proliferative changes, they were found in 7 of 7 (100%) in OGI group and were decreased by Ranibizumab and Conbercept to 5 of 7 (71.4%) and 4 of 7 (57.1%), respectively. Both Ranibizumab and Conbercept inhibited epiretinal scar formation at the wound site, with Conbercept showing the greatest effect (maximal length of scar (L), L_OGI = 503 ± 82.44 μm, L_Ranibizumab = 355 ± 43.66 μm, and L_Conbercept = 250.33 ± 36.02 μm).

Conclusion

Anti-VEGF treatments after OGI significantly attenuated the upregulation of growth factors and cytokines in the vitreous and prevented intravitreal proliferation and epiretinal scar formation and thus may protect against the development of posttraumatic complications such as proliferative vitreoretinopathy (PVR).

Vascular endothelial growth factor concentration in vitreous humor of patients with severe proliferative diabetic retinopathy after intravitreal injection of conbercept as an adjunctive therapy for vitrectomy

Background

Proliferative diabetic retinopathy (PDR) is a progressive stage of diabetic retinopathy featured by the formation of neovascular and proliferative membrane. Vascular endothelial growth factor (VEGF) acts as a pivot factor in the development of neovascularization. This study was to investigate the changes of intravitreal VEGF concentrations of severe PDR after intravitreal injection of conbercept (IVC) and its potential advantages to the following vitrectomy.

Methods

This was a prospective, interventional, randomized controlled study. Sixty eyes (60 patients) with severe PDR and 20 eyes from 20 patients with rhegmatogenous retinal detachment complicated with proliferative vitreoretinopathy were enrolled in this study. PDR eyes were randomly assigned to three groups by sortation randomization method with 20 eyes in each based on the interval of preoperative IVC (group A: 7 days, group B: 14 days, group C: non-IVC). Another 20 eyes without diabetes were enrolled as the non-diabetic control group (group D), receiving PPV directly. Vitreous specimens of all 80 patients were collected and evaluated afterwards. The intravitreal VEGF concentration of the four groups, and the total surgical time and the intraoperative bleeding rate of the PDR groups were recorded.

Results

The mean intravitreal VEGF concentrations of groups A–D were 66.6 ± 43.3, 93.1 ± 52.3, 161.4 ± 106.1 and 1.8 ± 1.2 pg/mL, respectively. It increased significantly in PDR patients (groups A, B and C) (P = 0.002, <0.001, and <0.001, respectively). PDR patients with preoperative IVC (groups A and B) presented significantly lower VEGF concentrations (P < 0.001 and 0.001), intraoperative bleeding rates (P = 0.004) and total surgical time (P < 0.001, P = 0.003) compared with group C. No statistical differences were presented between groups A and B on the three parameters.

Conclusion

Seven days and 14 days of preoperative IVC are equally efficient and safe for the vitrectomy of severe PDR patients through decreasing vitreous VEGF concentrations, intraoperative bleeding rate and total surgical times.

Effect of Vitamin E on Serum Levels of Vascular Endothelial Growth Factor and Angiopoietin-1 in Women with Polycystic Ovary Syndrome: A Pilot Randomized, Placebo-Controlled Trial

Background

Angiogenesis disturbances are common in women with polycystic ovary syndrome (PCOS). Vitamin E has antiangiogenic properties. Data on the effects of vitamin E on angiogenesis in PCOS is limited, so the current study was conducted to evaluate its effects on angiogenic indices in PCOS patients.

Materials and Methods

This randomized, double-blind, placebo-controlled trial was performed on 43 women aged 20-40 years, diagnosed with PCOS (Rotterdam criteria). It was performed at the referral clinic affiliated to Tabriz University of Medical Sciences, Tabriz, Iran, from April 2017 to September 2017. Patients were randomly assigned into two groups to receive either 400 IU/day vitamin E -as alpha tocopheryl acetate- (n=22) or placebo (n=21), for 8 weeks. Anthropometric, and angiogenic parameters including body weight, fat mass and fat free mass, vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), angiopoietin-1 (Ang- 1), and angiopoietin-2 (Ang-2) were measured by standard methods at the beginning and at the end of study. Statistical Package for Social Science version 25 was used for statistical analysis and P<0.05 were considered significant.

Results

After adjusting for potential confounders, we observed that vitamin E supplementation significantly reduced body weight, fat mass, Ang-1, Ang-1/Ang-2 ratio and VEGF (P<0.01). We did not observe any considerable effect for vitamin E on Ang-2 level or bFGF.

Conclusion

Vitamin E supplementation for 8 weeks in the PCOS women had beneficial effects on body weight, Ang- 1, Ang-1/Ang-2 ratio, and VEGF level (Registration number: IRCT201610193140N18).

Ocular Drug Delivery to the Retina: Current Innovations and Future Perspectives

Treatment options for retinal diseases, such as neovascular age-related macular degeneration, diabetic retinopathy, and retinal vascular disorders, have markedly expanded following the development of anti-vascular endothelial growth factor intravitreal injection methods. However, because intravitreal treatment requires monthly or bimonthly repeat injections to achieve optimal efficacy, recent investigations have focused on extended drug delivery systems to lengthen the treatment intervals in the long term. Dose escalation and increasing molecular weight of drugs, intravitreal implants and nanoparticles, hydrogels, combined systems, and port delivery systems are presently under preclinical and clinical investigations. In addition, less invasive techniques rather than intravitreal administration routes, such as topical, subconjunctival, suprachoroidal, subretinal, and trans-scleral, have been evaluated to reduce the treatment burden. Despite the latest advancements in the field of ophthalmic pharmacology, enhancing drug efficacy with high ocular bioavailability while avoiding systemic and local adverse effects is quite challenging. Consequently, despite the performance of numerous in vitro studies, only a few techniques have translated to clinical trials. This review discusses the recent developments in ocular drug delivery to the retina, the pharmacokinetics of intravitreal drugs, efforts to extend drug efficacy in the intraocular space, minimally invasive techniques for drug delivery to the retina, and future perspectives in this field.

Comparison of the effectiveness of conbercept and ranibizumab treatment for retinopathy of prematurity

PURPOSE

To compare the effectiveness of intravitreal conbercept and ranibizumab treatment for retinopathy of prematurity (ROP).

METHODS

In this retrospective study, the date of patients with ROP treated with intravitreal conbercept or ranibizumab from July 2012 to March 2018 with at least 12 months of follow-up at the Eye Center in People's Hospital of Peking University were analysed. Regression, progression or recurrence and peripheral retina vascularization were evaluated.

RESULTS

In total, 283 eyes (145 infants) with conbercept treatment and 916 eyes (480 infants) with ranibizumab treatment were enrolled. In zone I ROP and aggressive posterior ROP (APROP), the recurrence prevalence was 49.09% (108/220 eyes) and 28.57% (10/33 eyes), and the recurrence interval was 7.87 ± 0.65 (5.5-9.5) weeks and 10.6 ± 1.53 (10.5-13) weeks in the ranibizumab and conbercept groups, respectively. In zone II ROP disease, the recurrence prevalence was 23.56% (164/696 eyes) and 13.31% (33/248 eyes), and the interval of recurrence was 8.40 ± 0.88 (6-10.5) weeks and 11.4 ± 1.35 (11-13.5) weeks in the ranibizumab and conbercept groups, respectively. The recurrence prevalence was significantly higher with ranibizumab in Zone I ROP and APROP (p = 0.006) and Zone II ROP (p < 0.001), and the recurrence interval was significantly longer in the conbercept group than that in the ranibizumab (p < 0.001). There was no significant difference in the rate of retinal vascularization (p = 0.441).

CONCLUSION

Conbercept and ranibizumab are effective for treating ROP. Compared with ranibizumab, conbercept resulted in less recurrence and longer treatment intervals.

Intraocular pharmacokinetics of anti-vascular endothelial growth factor agents by intraoperative subretinal versus intravitreal injection in silicone oil-filled eyes of proliferative diabetic retinopathy: a randomized controlled pilot study

PURPOSE

Intraoperative subretinal anti-vascular endothelial growth factor (VEGF) injections have been used clinically in some case, but the pharmacokinetic characteristics have not yet been determined. In this pilot study, we investigate the pharmacokinetic parameters of anti-VEGF agents by intraoperative subretinal or intravitreal injection in silicone oil (SiO)-filled eyes of patients with proliferative diabetic retinopathy (PDR).

METHODS

Randomized controlled trial including 13 patients (16 eyes) with PDR underwent pars plana vitrectomy (PPV) with SiO tamponade and randomly received a subretinal (8 eyes) or intravitreal (8 eyes) conbercept injection (0.5 mg/0.05 ml) intraoperatively. Aqueous humour (AH) was obtained on the 1st, 3rd, 7th, 10th, 14th, 21st and 28th day after the injection. Drug concentrations in the AH were determined by enzyme-linked immunosorbent assay (ELISA). The last best-corrected visual acuity (BCVA) was examined 6 months postoperatively.

RESULTS

The clearance rate of anti-VEGF agents by subretinal injection was reduced in vitrectomized eyes with SiO tamponade (p < 0.05). With the same drug dose, subretinal injection (5.49 ± 6.11 μg/ml) resulted in higher drug concentrations in the AH when compared with intravitreal injection (0.42 ± 0.46 μg/ml, p = 0.001) 4 weeks after the treatment. The mean residence time last (MRT_0-t ) by subretinal injection (11.57 ± 0.83 days) was significantly longer than the mean MRT_0-t by intravitreal injection (7.10 ± 1.00 days, p < 0.001). A self-paired analysis showed that subretinal injection led to the BCVA improvement by +28.59 letters 6 months postoperatively (p = 0.028) while the BCVA did not improve significantly by intravitreal injection (p = 0.715).

CONCLUSIONS

The drug maintenance phase was prolonged by intraoperative subretinal injection in SiO-filled eyes of PDR. The results suggest that subretinal injection might be a valuable treatment option for the management of PDR.

New Anti-VEGF Drugs in Ophthalmology

:

This review focuses on 5 new anti-VEGF drugs in the advanced stage of clinical development (i.e., phase 3): conbercept, brolucizumab, port delivery system with ranibizumab, abicipar pegol and faricimab.

:

Results of clinical trials and the advantages of each drug compared to the available molecules are discussed in detail.

Biologic Therapy and Treatment Options in Diabetic Retinopathy with Diabetic Macular Edema

Proliferative diabetic retinopathy and diabetic macular edema can be a potentially sightthreatening disease if not treated correctly. It is directly correlated to the duration of diabetes and how well managed the patients' diabetes is. In the last 15 years, the treatment of diabetic eye disease has taken a quantum leap in methodology due to the group of biological agents named antivascular endothelial growth factor (anti-VEGF). The introduction of the first biological agent has revolutionized the treatment, not only in diabetic eye disease but also across most inflammatory eye diseases, causing leakage of fluid from the blood vessels i.e., in age-related macular degeneration. The availability of these biological agents, despite their considerable costs, have significantly improved the outcomes measured in visual acuity compared to more traditional treatments of diabetic retinopathy in the form of sole laser treatment and glycemic control. The agents demonstrate a favorable safety profile, but if the rarest and most severe side effects occur, there is a potential total loss of vision. This review aims to make an overview of the current pharmaceutical therapeutic options in the treatment of diabetic macular edema. This includes laser therapy, intravitreal steroids, and a primary focus on intravitreal antivascular endothelial growth factors.

Serum levels of cytokines in infants treated with conbercept for retinopathy of prematurity

Intravitreal anti-vascular endothelial growth factor (VEGF) agents have revolutionized the treatment of retinopathy of prematurity (ROP); however, there are concerns regarding the potential systemic complications caused by those treatments. This study aimed to determine the serum concentrations of cytokines in infants with ROP and to evaluate the changes in serum VEGF concentrations after intravitreal conbercept (IVC). Sixty infants with ROP treated with IVC 0.25 mg were included. Blood samples were collected before treatment as well as 1 week and 4 weeks after treatment. Serum levels of 45 types of cytokines were measured by a multiplex bead assay. We observed that IVC 0.25 mg in ROP patients suppressed the circulating levels of VEGF-A and VEGF-D as of 1 week after injection, and these growth factor levels returned to baseline at 4 weeks. No significant differences were observed in the serum levels of the other cytokines between baseline and 1 or 4 weeks after IVC.

Emerging drugs for the treatment of diabetic retinopathy

INTRODUCTION

Diabetic retinopathy (DR) is one of the main pathological features of the diabetes mellitus spectrum. It is estimated that in 2020 about 4 million people worldwide suffered from blindness or visual impairment caused by DR. Many patients cannot access treatment, mostly because of high costs, while others discontinue it prematurely due to the high number of intravitreal administrations required, or the occurrence of ocular complications, or discomfort in quality of life.

AREAS COVERED

The aims of this paper are to summarize the current understanding of the pathogenesis and treatment of diabetic retinopathy, focus on the most promising new approaches to treatment that are being evaluated in clinical trials, and outline the potential financial impact of new drugs in future markets.

EXPERT OPINION

Slow-release systems with steroids, anti-VEGF or sunitinib are promising. Oral imatinib would avoid the ocular complications of intravitreal drugs. Brolucizumab and abicipar pegol may be superior to aflibercept and ranibizumab with the advantage of less frequent administrations. Faricimab, active on Tie-2 receptors, is being evaluated in two phase 3 clinical trials. Further knowledge of the efficacy and safety of these drugs is necessary before their final approval for the treatment of diabetic retinopathy.

Clinical outcomes of 1 + PRN and 3 + Q3M regimens of intravitreal conbercept injection for exudative age-related macular degeneration

This retrospective study aimed to analyze the clinical outcomes of two regimens of intravitreal injections of conbercept [1+pro re nata (PRN) and 3 + Q3M] for the therapy of exudative age-related macular degeneration (AMD). In total, 105 eyes diagnosed with exudative AMD were enrolled. The eyes in the 1+PRN group (n = 51) received intravitreal injection of conbercept one time, followed by PRN retreatment. The eyes in the 3 + Q3M group (n = 54) received intravitreal injection of conbercept on three consecutive monthly, subsequently, once every three months for three times. After treatment, patients were followed up for 12 months. The best-corrected visual acuity (BCVA), central retinal thickness (CRT), and choroidal neovascularization (CNV) leakage area were compared before and after treatment. Moreover, the number of injections and adverse reactions were recorded. Compared with the 1+PRN group, BCVA was significantly improved and CRT was remarkably decreased in the 3 + Q3M group at 3, 6 and 12 months after operation. The disappeared or reduced CNV leakage area (93%) of the 3 + Q3M group was higher than that of the 1 + PRN group at the last follow-up. Moreover, the mean numbers of conbercept injections of the 1 + PRN group were less than the 3 + Q3M group. During the follow-up, there were no serious adverse reactions or ocular complications. This study reveals that intravitreal injection of conbercept using 3 + Q3M regimen has certain advantages than 1 + PRN regimen in extending drug delivery interval, improving patient’s vision, and reducing CRT.

Intravitreal conbercept improves outcome in patients undergoing vitrectomy for proliferative diabetic retinopathy: A systematic review and meta-analysis

OBJECTIVES

To evaluate the latest evidence concerning the efficacy of conbercept on vitrectomy for proliferative diabetic retinopathy (PDR) and its efficacy compared to control and other antivascular endothelial growth factor.

METHODS

We performed a systematic literature search on topics that assess the role of conbercept in patients undergoing vitrectomy for PDR from inception to November 2019, using PubMed, EuropePMC, Cochrane Central Database, ProQuest, ScienceDirect, and Clinicaltrials.gov. Two researchers independently searched literature, extracted data, and evaluated the risk of bias. RevMan 5.3 and StataMP 16 software were used to perform data analysis.

RESULTS

There were 699 cases (eyes) from eight studies. Baseline best-corrected visual acuity (BCVA) was better in the control group compared to conbercept group (mean difference [MD] = 0.13, I²   = 0%). A greater BCVA improvement was observed in the conbercept group after 1-month (MD = -0.27, I²   = 1%), 3-month (MD = -0.28, I²   = 0%), and 6-month (MD = -0.20, I²   = 78%) follow-up. The need for endodiathermy (odds ratio [OR] = 0.20, I²   = 0%) and silicone oil tamponade use (OR = 0.59, I²   = 72%) and intraoperative bleeding (OR = 0.11, I²   = 33%) was lower in conbercept group. Postoperative early (OR = 0.22, I²   = 0%) and late (OR = 0.47, I²   = 0%) vitreous hemorrhage was lower in conbercept group. There was no significant difference in BCVA improvement and intraoperative outcome between conbercept and ranibizumab.

CONCLUSIONS

Intravitreal conbercept was associated with a more significant BCVA improvement, better intraoperative outcome, and less postoperative vitreous hemorrhage compared to no conbercept.

Anti-VEGF Treatment and Response in Age-related Macular Degeneration: Disease's Susceptibility, Pharmacogenetics and Pharmacokinetics

The current review is focussing different factors that contribute and directly correlate to the onset and progression of Age-related Macular Degeneration (AMD). In particular, the susceptibility to AMD due to genetic and non-genetic factors and the establishment of risk scores, based on the analysis of different genes to measure the risk of developing the disease. A correlation with the actual therapeutic landscape to treat AMD patients from the point of view of pharmacokinetics and pharmacogenetics is also exposed. Treatments commonly used, as well as different regimes of administration, will be especially important in trying to classify individuals as "responders" and "non-responders". Analysis of different genes correlated with drug response and also the emerging field of microRNAs (miRNAs) as possible biomarkers for early AMD detection and response will be also reviewed. This article aims to provide the reader a review of different publications correlated with AMD from the molecular and kinetic point of view as well as its commonly used treatments, major pitfalls and future directions that, to our knowledge, could be interesting to assess and follow in order to develop a personalized medicine model for AMD.

Intraocular Pharmacokinetics and Safety of Subretinal Injection Compared with Intravitreal Application of Conbercept in Vitrectomized Rabbit Eyes

Purpose

To evaluate the ocular pharmacokinetic properties of subretinal conbercept injection in vitrectomized rabbit eyes and to compare them with those by intravitreal injection.

Methods

The following groups of New Zealand white rabbits received conbercept injections (0.5 mg/0.05 ml): a subretinal group (subretinal injection in vitrectomized eyes), an intravitreal group (intravitreal injection in vitrectomized eyes), and a control group (intravitreal injection in nonvitrectomized eyes). Drug concentrations in the aqueous humor (AH), the vitreous humor (VH), and the retina were measured by the enzyme-linked immunosorbent assay (ELISA), and pharmacokinetic parameters were calculated. Ophthalmic B-ultrasonography, electroretinogram (ERG), and hematoxylin and eosin (H&E) staining were performed to evaluate the safety of subretinal injection.

Results

On the 28^th day after injection, the drug level in the subretinal group was significantly higher than that in the intravitreal group in the AH (0.90 ± 0.25 μg/ml and 0.11 ± 0.07 μg/ml and 0.11 ± 0.07 P < 0.001, respectively) and the VH (5.00 ± 3.86 μg/ml and 0.11 ± 0.07 μg/ml and 0.11 ± 0.07 P < 0.001, respectively) and the VH (5.00 ± 3.86 P < 0.001, respectively) and the VH (5.00 ± 3.86 P < 0.001, respectively) and the VH (5.00 ± 3.86 

Conclusions

Our study indicates that applying conbercept by subretinal injection can reduce the drug clearance rate and sustain a long maintenance period in ocular tissue, which suggests that subretinal conbercept injection may be a potentially valuable treatment option.

Different conbercept injection strategies for the treatment of exudative age-related macular degeneration: A retrospective cohort study

Conbercept is a novel anti-vascular endothelial growth factor for the treatment of age-related macular degeneration (AMD). The most optimal injection strategy is unknown. To assess the effectiveness of intravitreal injection of conbercept using the 3 + pro re nata (PRN) and 3 + Q3 M strategies for the treatment of exudative AMD.From January 2015 to January 2018, patients confirmed with exudative AMD at Qilu Hospital of Shandong University were included in this retrospective study. Intravitreal injection of 0.5 mg of conbercept was conducted either with the 3 + PRN or 3 + Q3 M strategy. Best-corrected visual acuity (BCVA), intraocular pressure, and optical coherence tomography were conducted at 1 and 2 weeks, then every month. fundus fluorescein angiography examination was conducted every 3 months.There were 106 eyes from 106 patients. The number of follow-ups (3 + Q3 M: 12.4 ± 1.3 vs 3 + PRN: 12.9 ± 1.6, P = .079) and the follow-up time (3 + Q3 M: 12.7 ± 0.6 vs 3 + PRN: 12.5 ± 0.7 months, P = .121) were similar in the 2 groups. The number of injections was less in 3 + PRN than 3 + Q3 M (5.3 ± 1.0 vs 6.0 ± 0.0, P < .001) The BCVA at months 7 and 9 to 12 in the 3 + Q3 M (n = 51) group were lower than for 3 + PRN (n = 55) (all P < .05). The CRT at months 9 to 12 in the 3 + Q3 M group was lower than in the 3 + PRN group (all P < .05). There were no differences between the 2 groups regarding the exudation area during follow-up. No serious treatment-related ocular complications or serious systemic adverse events were found.The 3 + PRN and 3 + Q3 M strategies of intravitreal injection of conbercept are effective in treating exudative AMD. The 3 + Q3 M strategy needs more injection but is more effective in increasing visual acuity and reducing macular CRT than the 3 + PRN strategy.

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

Administration of RC28-E, a VEGF/bFGF dual decoy receptor (IgG1 Fc-fusion protein), have shown relative therapeutic value in ocular in vivo models, including laser-induced choroidal neovascularization (CNV) in monkeys and streptozotocin (STZ)-induced diabetic retinopathy (DR) in rats. In the present study, we have elucidated the pharmacokinetics profiles of RC28-E at the systemic, vitreous and aqueous humor after administration in a primate model (Macaca fascicularis). Moreover, here we tease out the ocular tissue distribution of RC28-E after intravitreal administration, and we also determine the systemic bioavailability after both intravitreal and intravenous administration. Our results show that RC28-E is rapidly and well-distributed into ocular tissues after intravitreal administration. Drug exposure in choroid and retina was approximately one-quarter and one-twelfth of that in vitreous humor, while its half-life in vitreous and aqueous humor were well-sustained (3.3 and 3.0 days). Remarkably, RC28-E could cross the blood-ocular barrier, and the systemic bioavailability of RC28-E was ~25%. No drug accumulation after multiple administration was noticed, but low titers of antibody produce against RC28-E were detected. Overall, RC28-E exhibited high clinical value due to adequate pharmacokinetic profiling, safety and efficacy.

Preoperative Intravitreal Conbercept Facilitates Vitrectomy in Proliferative Diabetic Retinopathy: Is Attention Required for the Fellow Eye?

Purpose

To evaluate the effect of preoperative intravitreal conbercept (IVC) injection on patients with proliferative diabetic retinopathy (PDR).

Methods

Medical records of patients who underwent vitrectomy due to complications of PDR were retrospectively reviewed. Patients were grouped as the IVC group and non-IVC group according to preoperative IVC. Preoperative, intraoperative, and postoperative data of both eyes were collected. The main outcome measures were best-corrected visual acuity (BCVA), intraocular pressure (IOP), central retinal thickness (CRT), and incidence of tractional retinal detachment (TRD).

Results

A total of 37 cases were included, 16 in the IVC group and 21 in the non-IVC group. Preoperative IVC significantly reduced surgical duration (IVC vs. non-IVC, 88.9 ± 11.9 min vs. 97.8 ± 12.8 min, p  <  0.05). In the vitrectomized eye, no significant difference existed between the IVC group and non-IVC group regarding postoperative BCVA (logMAR, 1.20 ± 0.53 vs. 1.27 ± 0.54, p = 0.68), IOP (16.5 ± 2.9 mmHg vs. 15.6 ± 3.7 mmHg, p = 0.44), and CRT (330.1 ± 35.2 μm vs. 319.2 ± 32.5 μm, p=0.34). In the fellow eye, 6 cases in the IVC group were diagnosed with TRD during postoperative follow-up, while only 2 cases were diagnosed in the non-IVC group (p  <  0.05).

Conclusion

Preoperative intravitreal injection of conbercept has effectively facilitated vitrectomy in PDR patients, but it potentially promotes tractional retinal detachment in the fellow eye following preoperative injection.

Conbercept for Treatment of Neovascular Age-related Macular Degeneration: Results of the Randomized Phase 3 PHOENIX Study

PURPOSE

Age-related macular degeneration (AMD) can cause irreversible vision loss leading to blindness. We aim to evaluate the efficacy and safety of intravitreal injections of 0.5 mg conbercept, a new anti-vascular endothelial growth factor (anti-VEGF) drug, for treatment of AMD on a schedule more manageable for patients.

DESIGN

A prospective, double-masked, multicenter, sham-controlled, phase III randomized trial.

METHODS

Patients: Patients with choroidal neovascularization (CNV) secondary to AMD were enrolled and randomized to the conbercept group or the sham control group.

INTERVENTION

The conbercept group received intravitreal injections of conbercept (0.5 mg) once monthly for the first 3 months, then once quarterly until month 12 (3 + Q3M). The sham group received first 3 monthly sham injections and then 3 monthly injections of conbercept (0.5 mg) followed by quarterly administrations until month 12.

MAIN OUTCOME MEASURES

The primary endpoint was mean change from baseline in best-corrected visual acuity (BCVA) at month 3.

RESULTS

A total of 114 patients (91.9%) from 9 sites in China completed the 12-month study. At the 3-month primary endpoint, the mean changes in BCVA from baseline were +9.20 letters in the conbercept group and +2.02 letters in the sham group, respectively (P < .001). At 12 months, the mean changes from baseline in BCVA letter score were +9.98 letters in the conbercept group and +8.81 letters in the sham group (P = .64). The most common ocular adverse events were associated with intravitreal injections, such as conjunctival hemorrhage, and increased intraocular pressure.

CONCLUSIONS

A conbercept dosing regimen of 3 initial monthly administrations followed by quarterly treatments is effective for treatment of AMD. In previous reports, other anti-VEGF agents were unable to maintain similar clinical benefits with the same regimen.

Pharmacokinetic Simulations of Intravitreal Biologicals: Aspects of Drug Delivery to the Posterior and Anterior Segments

Biologicals are important ocular drugs that are be delivered using monthly and bimonthly intravitreal injections to treat retinal diseases, such as age-related macular degeneration. Long acting delivery systems are needed for prolongation of their dosing interval. Intravitreal biologicals are eliminated from the eye via the aqueous humor outflow. Thus, the anterior and posterior segments are exposed to the drug. We utilized a kinetic simulation model to estimate protein drug concentrations in the vitreous and aqueous humor after bolus injection and controlled release administration to the vitreous. The simulations predicted accurately the experimental levels of 5 biologicals in the vitreous and aqueous humor. The good match between the simulations and experimental data demonstrated almost complete anterior segment bioavailability, and major dose sparing with ocular controlled release systems. Overall, the model is a useful tool in the design of intraocular delivery of biologicals.

The efficacy and safety of aflibercept and conbercept in diabetic macular edema

Diabetic macular edema (DME) has shown an increasing prevalence during the past years and is the leading cause of diabetic retinopathy blindness. Traditional treatment modalities include laser and corticosteroid therapy, which, however, either act through unclear mechanisms or cause cataracts and elevated intraocular pressure. In recent years, as the pathogenic role of VEGF in DME has been well-recognized, the intravitreal injection of anti-VEGF drugs has become the first-line treatment of DME due to their great efficacy in improving visual acuity and mitigating macular edema. Advantages have been shown for aflibercept and conbercept, the two recombinant decoy receptors that can bind VEGF with high specificity and affinity, in DME treatment in clinical trials conducted both worldwide and in People’s Republic of China. This review introduces the structural characteristics and molecular mechanisms of action of these two anti-VEGF drugs, and summarizes the clinical trials evaluating their efficacy and safety, with the hope to provide clues for designing optimal and personalized therapeutic regimens for DME patients.

Efficacy comparison of intravitreal injections of conbercept and ranibizumab for severe proliferative diabetic retinopathy

OBJECTIVE

To determine the efficacy of preoperative intravitreal injections of conbercept (IVC) and ranibizumab (IVR) on postoperative best-corrected visual acuity (BCVA), vitreous hemorrhage (VH), and neovascular glaucoma (NVG) in a population with proliferative diabetic retinopathy (PDR) undergoing vitrectomy.

DESIGN

Retrospective, cross-sectional study.

PARTICIPANTS

386 patients with severe PDR (428 eyes).

METHODS

The patients who did not receive IVC or IVR were assigned to group A (125 eyes), the patients who received IVR (0.5 mg) were assigned to group B (146 eyes), and the patients who received IVC (0.5 mg) were assigned to group C (157 eyes).

RESULTS

Both group B (p = 0.009) and group C (p = 0.002) had better postoperative BCVA than group A. Early postoperative VH occurred significantly less frequently in group B (22.60%; p = 0.007) and group C (12.10%; p < 0.001) than in group A (37.60%). Importantly, the incidences of postoperative NVG in group B (2.74%; p = 0.001) and group C (0.64%; p < 0.001) were both significantly less than that in group A (15.20%). However, there was no significant difference in the incidences of postoperative NVG between groups B and C (p = 0.325).

CONCLUSIONS

The contribution of preoperative IVC to an improved BCVA for patients with severe PDR was better than that of IVR, and IVC decreased the risk of postoperative early VH. Pretreatment with IVC or IVR reduced the incidence of postoperative NVG based on the 24-month follow-up data.