PENETRATION OF BEVACIZUMAB AND RANIBIZUMAB THROUGH RETINAL PIGMENT EPITHELIAL LAYER IN VITRO

Inefficacy of anti-VEGF therapy reflected in VEGF-mediated photoreceptor degeneration

Retinal neovascularization (RNV) is primarily driven by vascular endothelial growth factor (VEGF). However, current anti-VEGF therapies are limited by short half-lives and repeated injections, which reduce patient quality of life and increase medical risks. Additionally, not all patients benefit from anti-VEGF monotherapy, and some problems, such as unsatisfactory vision recovery, persist after long-term treatment. In this study, we constructed a recombinant adeno-associated virus (AAV), AAV2-SPLTH, which encodes an anti-VEGF antibody similar to bevacizumab, and assessed its effects in a doxycycline-induced Tet-opsin-VEGFA mouse model of RNV. AAV2-SPLTH effectively inhibited retinal leakage, RNV progression, and photoreceptor apoptosis in a Tet-opsin-VEGF mouse model. However, proteomic sequencing showed that AAV2-SPLTH failed to rescue the expression of phototransduction-related genes, which corresponded to reduced photoreceptor cell numbers. This study suggests that anti-VEGF monotherapy can significantly inhibit RNV to some extent but may not be enough to save visual function in the long term.

Electroretinographic Responses in Retinopathy of Prematurity Treated Using Intravitreal Bevacizumab or Laser

PURPOSE

Intravitreal injection of bevacizumab (IVB) offers advantages over laser photoablation for treatment of type 1 retinopathy of prematurity (ROP). However, retinal function has not, to date, been quantitatively compared following these interventions. Therefore, electroretinography (ERG) was used compare retinal function among eyes treated using IVB or laser, and control eyes. In addition, among the IVB-treated eyes, ERG was used to compare function in individuals in whom subsequent laser was and was not required.

DESIGN

Prospective clinical cohort study.

METHODS

ERG was used to record dark- and light-adapted stimulus/response functions in 21 children treated using IVB (12 of whom required subsequent laser in at least 1 eye for persistent avascular retina [PAR]). Sensitivity and amplitude parameters were derived from the a-wave, b-wave, and oscillatory potentials (OPs), representing activity in photoreceptor, postreceptor, and inner retinal cells, respectively. These parameters were then referenced to those of 76 healthy, term-born controls and compared to those of 10 children treated using laser only.

RESULTS

In children with treated ROP, every ERG parameter was significantly below the mean in controls. However, these significant ERG deficits did not differ between IVB- and laser-treated eyes. Among children treated using IVB, no ERG parameter was significantly associated with dose or need for subsequent laser.

CONCLUSION

Retinal function was significantly impaired in treated ROP eyes. Function in IVB-treated eyes did not differ from that in laser-treated eyes. Functional differences also did not distinguish those IVB-treated eyes that would subsequently need laser for PAR.

Recent advances and future prospects: current status and challenges of the intraocular injection of drugs for vitreoretinal diseases

Effective drug therapy for vitreoretinal disease is a major challenge in the field of ophthalmology; various protective systems, including anatomical and physiological barriers, complicate drug delivery to precise targets. However, as the eye is a closed cavity, it is an ideal target for local administration. Various types of drug delivery systems have been investigated that take advantage of this aspect of the eye, enhancing ocular permeability and optimizing local drug concentrations. Many drugs, mainly anti-VEGF drugs, have been evaluated in clinical trials and have provided clinical benefit to many patients. In the near future, innovative drug delivery systems will be developed to avoid frequent intravitreal administration of drugs and maintain effective drug concentrations for a long period of time. Here, we review the published literature on various drugs and administration routes and current clinical applications. Recent advances in drug delivery systems are discussed along with future prospects.

Factors That Can Prolong Ocular Treatment Duration in Age-Related Macular Degeneration

Intravitreal injections of anti-vascular endothelial growth factor (VEGF) agents are used to treat wet age-related macular degeneration (wAMD); however, they are associated with a considerable treatment burden and poor real-world outcomes. The molecular size and charge of anti-VEGF agents influence drug pharmacokinetics in the vitreous and peak drug efficacy. This article reviews the established and novel strategies to prolong drug action, in the vitreal cavity, and thus reduce dosing frequency. Increased ocular residency can be attained by increasing drug size as with large molecules, such as KSI-301; adding polyethylene glycol to pegcetacoplan (APL-2) or avacincaptad pegol to increase molecular size; or binding to other targets that increase molecular size, such as vitreal albumin in the case of BI-X. Faricimab is a bispecific antibody in which the fragment crystallizable portion is engineered to prolong ocular residency and reduce systemic exposure. Conversely, small VEGF-binding molecules, such as brolucizumab, can be administered at higher clinical doses, with the potential for prolonged clinical activity versus larger molecules. Other important considerations include sustained drug delivery routes, such as the ranibizumab port delivery system or subconjunctival or suprachoroidal injection. More effective and longer-lasting treatments are needed for wAMD to prolong drug action and reduce dosing frequency. Several strategies are under investigation and the prevention of vision loss in patients with AMD or other retinal diseases may be attainable in the near future.

Difference in Lesion Reactivation between Pure Type 2 and Mixed Type 1 and 2 Macular Neovascularization and its Influence on Long-Term Treatment Outcomes

PURPOSE

To compare lesion reactivation and treatment outcomes between pure type 2 and mixed type 1 and 2 macular neovascularization (MNV) treated with anti-vascular endothelial growth factor (VEGF).

METHODS

This retrospective study included 155 patients diagnosed with type 2 MNV. After the initial loading injections, as-needed retreatment was provided. The difference in first lesion reactivation after the initial treatment was evaluated between pure type 2 MNV (pure type 2 group, n = 37) and mixed type 1 and 2 MNV (mixed group, n = 118). The degree of change in the best-corrected visual acuity (BCVA) was also compared between the two groups.

RESULTS

The mean follow-up period was 32.7 ± 13.7 months. Lesion reactivation differed significantly between the type 2 (60.0%) and mixed (84.5%) (P = .004) groups. The degree of visual change during the follow-up period also differed significantly between the pure type 2 (mean 2.8 lines of improvement) and mixed (mean 0.2 lines of deterioration) (P = .008) groups. In multivariate analysis, lesion type (P = .012) and baseline visual acuity (P = .002) were significantly associated with ≥2 lines of visual improvement.

CONCLUSIONS

Lesion reactivation and treatment outcomes differed between pure type 2 and mixed type 1 and 2 MNV. These results suggested the need for different treatment strategies for these two MNV subtypes.

Comparison of Intraocular Cytokine Levels of Choroidal Neovascularization Secondary to Different Retinopathies

Purpose: To investigate and compare the aqueous concentrations of vascular endothelial growth factor (VEGF) and other inflammatory cytokines in various choroidal neovascularization (CNV) diseases and types.

Methods: This observational study included 127 naive eyes with CNV and 43 control eyes with cataracts. Aqueous humor (AH) samples were obtained prior to intravitreal anti-VEGF injection or cataract surgery. Multiple inflammatory cytokines, including VEGF, interleukin (IL) 6, IL-8, IL-10, interferon-inducible protein 10 (IP-10), and monocyte chemotactic protein 1 (MCP-1) levels, were measured using a multiplex bead assay. The angiogenesis index was defined as the ratio of IP-10 to MCP-1. In addition, the relationship among AH cytokine levels, central macular thickness (CMT), and CNV size on optical coherence tomography angiography (OCTA) was evaluated.

Results: Except in the myopic CNV group (P = 0.452), the AH concentration of VEGF was significantly higher in all other CNV groups than in the control group (P < 0.05 for all comparisons). IL-8, IL-10, IP-10, and MCP-1 levels (P < 0.05 for all groups) were significantly higher in all CNV diseases except those with neovascular central serous chorioretinopathy. The angiogenesis index was significantly higher in all CNV diseases (P < 0.05 for all comparisons). The VEGF level may be associated with the size of the CNV on OCTA (p = 0.043).

Conclusions: The level of intraocular inflammatory cytokines varied among different CNV diseases and CNV types. Therefore, the angiogenesis index may be a more sensitive indicator of angiogenesis.

Human Platelets Take up Anti-VEGF Agents

Purpose

Growing evidence suggests different systemic exposure of anti-vascular endothelial growth factor (anti-VEGF) agents with repeated intravitreal application. Since the penetration of anti-VEGF agents through vascular barrier was reported, the interaction of anti-VEGF with nonresident platelets has become a topic of interest. The purpose of this study was to evaluate, with the help of visualization techniques, whether platelets take up the anti-VEGF agents ranibizumab, aflibercept, and bevacizumab.

Methods

The uptake of anti-VEGF agents with or without VEGF treatment was investigated using immunofluorescence and immunogold staining in human platelets. The role of actin filaments and clathrin-coated vesicles in the transport of ranibizumab, aflibercept, and bevacizumab was evaluated by two pharmacologic inhibitors: staurosporine (protein kinase C inhibitor) and cytochalasin D.

Results

All three anti-VEGF agents were taken up by platelets and colocalized with VEGF. Ranibizumab and aflibercept were mainly detected in alpha-granules; however, bevacizumab was equally localized in alpha-granules and in platelet vesicles. Both staurosporine and cytochalasin D completely inhibited the uptake of aflibercept into platelets. Both pharmacological inhibitors also decreased the transport of ranibizumab and bevacizumab into platelets. Bevacizumab was significantly more frequently colocalized within clathrin-coated vesicles than ranibizumab and aflibercept.

Conclusion

All three anti-VEGF agents are taken up by platelets and internalized in alpha-granules, which may result in a higher local exposure of anti-VEGF after the activation of platelets, potentially contributing to arterial thromboembolic events. Clathrin-coated vesicles seem to be more prominent in the transport of bevacizumab than ranibizumab and aflibercept. Nevertheless, whether the different localization and transport of bevacizumab are truly related to specific differences of receptor-mediated endocytosis has to be revealed by further research.

Prospective Study of Vessel Density by Optical Coherence Tomography Angiography After Intravitreal Bevacizumab in Exudative Age-Related Macular Degeneration

INTRODUCTION

The aim of this study was to evaluate retinal and choriocapillaris (CC) vessel density, using optical coherence tomography angiography (OCTA), in the macular region at baseline and after three once-monthly intravitreal injections of bevacizumab (loading phase) in patients affected by exudative age-related macular degeneration (AMD).

METHODS

A total 38 eyes of 38 patients with exudative AMD (16 women, 22 men; mean age 72.47 ± 7.46 years) were included in this study. We evaluated vessel density in different macular areas (whole image, fovea and parafovea) of the superficial capillary plexus (SCP), deep capillary plexus (DCP) and CC. In addition, central macular thickness (CMT) and choroidal thickness in the foveal region and 500 µm in the nasal and temporal directions were analyzed by enhanced depth image-OCT.

RESULTS

There were no significant differences in vessel density in the SCP, DCP and CC after the loading phase compared to baseline (p > 0.05). In contrast, CMT (p = 0.039; 320.63 ± 175.05 vs. 372.47 ± 167.05 µm) and subfoveal choroidal thickness (SFCT) (p < 0.001; 189.21 ± 37.66 µm vs 170.37 ± 37.96 µm) significantly decreased after the loading phase compared to baseline. No significant correlations were found between SFCT and CC vessel density in the fovea, and between CMT and SCP and DCP (p > 0.05) at baseline and after the loading phase. Also, best corrected visual acuity did not correlate with CMT, SCP and DCP at baseline and after treatment (p > 0.05).

CONCLUSION

Macular and choroidal thickness did not correlate with vessel density, but probably correlated to vascular exudation. The anti-VEGF treatment, acting on vascular hyperpermeability, determines the reduction of the retinal and choroidal exudation, resulting in a decrease of their thicknesses. Consequently, these parameters could reflect the effectiveness of the anti-VEGF injections for treating exudative AMD respect to OCTA parameters.

TRIAL REGISTRATION

ClinicalTrials.gov indentifier, NTC04138420.

Effect Of Bevacizumab On Growth Of Human Nasal Polyposis In Vitro; An Off-Label Use Of Anti-Angiogenic Agent For Nasal Polyposis Treatment

Introduction

Nasal polyposis (NP) is a frequent problem during adulthood. Treatment of NP is primarily based on drugs, such as oral or topical steroids and in some types, by surgery. Despite of available therapeutic options for NP, recurrence after polypectomy is found. Vascular endothelial growth factor (VEGF) is a known factor involved in NP. Bevacizumab is a monoclonal antibody, which acts against VEGF.

Aim

Regarding the availability of bevacizumab and its use in ophthalmic off-label application, in this study, we hypothesized that it could be a choice of non-invasive treatment. The researchers aimed at evaluating the use of bevacizumab in vitro on the growth of NP.

Materials and methods

In this experimental study, the researchers used eight non-allergic NP tissues from patients admitted for polypectomy clinic of Imam Reza Hospital, Mashhad. Tissues were cultured in DMEM medium based on standard protocols in the presence or absence of bevacizumab (10 to 250 μM) then incubated. The mean of the responses was reported. The level of VEGF and MTT test for NP epithelial cell viability were determined for each group. Data were analyzed using the SPSS software.

Results

The researchers demonstrated that bevacizumab leads to a decrease in the level of VEGF (the most common cause of angiogenesis in NP) in media culture of NP, dose-dependently (P<0.001). The highest mean was related to the 10-μM group and the least mean was related to the 250-μM group. In MTT test after 5 days, it was shown that the percentage of viable epithelial NP cells (due to apoptosis) was decreased dose-dependently and could lead to resolving NP tissue (P<0.001), significantly.

Conclusion

This study showed that bevacizumab could help decrease the growth of NP tissue dose-dependently in organ culture in vitro by inhibiting VEGF. It seems that bevacizumab could be a good candidate for the treatment of non-allergic NP.

Responses of Types 1 and 2 Neovascularization in Age-Related Macular Degeneration to Anti-Vascular Endothelial Growth Factor Treatment: Optical Coherence Tomography Angiography Analysis

Purpose: To compare the responses of types 1 (sub-pigment epithelial) and 2 (subretinal) neovascularization in neovascular age-related macular degeneration (AMD) to anti-vascular endothelial growth factor (VEGF) treatment. Methods: Fifty-five treatment-naïve neovascular AMD eyes (53 patients) were retrospectively included for analysis. All patients were treated with three loading injections of anti-VEGF agent, followed by further injections as required. The lesion size and vascular density of type 1 and 2 lesions before and after treatment for 12 months were analyzed using optical coherence tomography angiography (OCTA). Results: The mean lesion size of the type 1 neovascularization group (42 eyes) showed no significant change from 2.12 ± 1.01 mm² at baseline to 2.08 ± 0.91 mm² at 12 months (P = .682). However, the mean lesion size of type 2 neovascularization significantly decreased from 1.23 ± 0.93 mm² at baseline to 0.79 ± 0.61 mm² at 12 months (P = .022). The proportion of eyes with lesion sizes that decreased by more than 40% from baseline was also significantly higher for the type 2 compared to the type 1 neovascularization group (46.2% versus 11.9%, P = .007). Vascular density showed no significant changes for both groups after treatment and showed no association with the change in lesion size. There was no significant difference between the groups in terms of visual acuity improvement. Conclusion: OCTA analysis revealed different responses to anti-VEGF treatment depending on the location of neovascularization in neovascular AMD. Type 2 neovascularization was significantly regressed compared to type 1 neovascularization after anti-VEGF treatment. However, the changes in vascular density and visual outcome showed no significant differences between groups after 12 months of treatment.

Assessment of Ocriplasmin Effects on the Vitreoretinal Compartment in Porcine and Human Model Systems

Ocriplasmin (Jetrea®) is a recombinant protease used to treat vitreomacular traction. To gain insight into vitreoretinal observations reported after ocriplasmin treatment, we have developed an in vivo porcine ocriplasmin-induced posterior vitreous detachment (PVD) model in which we investigated vitreoretinal tissues by optical coherence tomography, histology, and cytokine profiling. Eight weeks postinjection, ocriplasmin yielded PVD in 82% of eyes. Subretinal fluid (85%) and vitreous hyperreflective spots (45%) were resolved by week 3. Histological analysis of extracellular matrix (ECM) proteins such as laminin, fibronectin, and collagen IV indicated no retinal ocriplasmin-induced ECM distribution changes. Retinal morphology was unaffected in all eyes. Cytokine profiles of ocriplasmin-treated eyes were not different from vehicle. In cell-based electrical resistance assays, blood-retinal barrier permeability was altered by ocriplasmin concentrations of 6 μg/mL and higher, with all effects being nontoxic, cell-type specific, and reversible. Ocriplasmin was actively taken up by RPE and Müller cells, and our data suggest both lysosomal and transcellular clearance routes for ocriplasmin. In conclusion, transient hyperreflective spots and fluid in a porcine ocriplasmin-induced PVD model did not correlate with retinal ECM rearrangement nor inflammation. Reversible in vitro effects on blood-retinal barrier permeability provide grounds for a hypothesis on the mechanisms behind transient subretinal fluid observed in ocriplasmin-treated patients.

Ocular Pharmacokinetics of Therapeutic Antibodies Given by Intravitreal Injection: Estimation of Retinal Permeabilities Using a 3-Compartment Semi-Mechanistic Model

Intravitreally (IVT) injected macromolecules for the treatment of age-related macular degeneration must permeate through the inner limiting membrane (ILM) into the retina and through the retinal pigment epithelium (RPE) to enter the choroid. A quantitative understanding of intraocular transport mechanisms, elimination pathways, and the effect of molecular size is currently incomplete. We present a semimechanistic, 3-compartment (retina, vitreous, and aqueous) pharmacokinetic (PK) model, expressed using linear ordinary differential equations (ODEs), to describe the molecular concentrations following a single IVT injection. The model was fit to experimental rabbit data, with Fab, Fc, IgG, and IgG null antibodies and antibody fragments, to estimate key ocular pharmacokinetic parameters. The model predicts an ocular half-life, t_1/2, which is the same for all compartments and dependent on the hydrodynamic radius (R_h) of the respective molecules, consistent with observations from the experimental data. Estimates of the permeabilities of the RPE and ILM are derived for R_h values ranging from 2.5 to 4.9 nm, and are found to be in good agreement with ex-vivo measurements from bovine eyes. We show that the ratio of these permeabilities largely determines the ratio of the molecular concentrations in the retina and vitreal compartments and their dependence on R_h. The model further provides estimates for the ratio of fluxes corresponding to the elimination pathways from the eye, i.e., aqueous humor to retina/choroid, which increase from 5:1 to 7:1 as R_h decreases. Our semimechanistic model provides a quantitative framework for interpreting ocular PK and the effects of molecule size on rate-determining parameters. We have shown that intraocular permeabilities can be reasonably estimated from 3-compartment ocular PK data and can determine how these parameters influence the half-life, retinal permeation, and elimination of intravitreally injected molecules from the eye.

Effect of intravitreal ranibizumab on the ocular circulation of the untreated fellow eye

Purpose

To evaluate the effects of unilateral intravitreal ranibizumab (IVR) on the ocular circulation of the fellow eyes.

Methods

Fifteen eyes of 15 patients with macular edema (average age 69.6 ± 11.8 years) were studied. Eleven eyes had diabetic macular edema (DME) and four eyes had macular edema associated with a branch retinal vein occlusion. Each eye received 0.5 mg of IVR. The blood circulation on the optic nerve head of the treated and untreated eyes were determined by laser speckle flowgraphy (LSFG, Softcare Co., Ltd) before, 1 day, and 1 week after the IVR. The mean blur rate (MBR) and the relative changes of the MBRs determined as dMBR(%) = 100−(MBR before/MB after) × 100) were evaluated. The central macular thickness (CMT) and the rate of reduction in the thickness (dCMT = 100−(CMT before/CMT after) × 100) were also evaluated.

Results

The mean dMBR was significantly higher in the treated eyes than the untreated eyes at 1 day (−16.4 ± 17.0% vs 2.31 ± 19.3%) and at 1 week (−12.0 ± 14.6% vs 4.50 ± 25.9%) after the IVR (P = 0.02, paired t tests).

Conclusion

These findings indicate that if ranibizumab enters the systemic circulation, the concentration is not high enough to affect the ocular circulation of the fellow eyes.

Comparison of Ranibizumab and Bevacizumab for Macular Edema Associated with Branch Retinal Vein Occlusion

PURPOSE

To assess the effectiveness and safety of intravitreal ranibizumab compared with bevacizumab for the treatment of macular edema associated with branch retinal vein occlusion (BRVO).

METHODS

This was a retrospective study of 80 eyes with macular edema associated with BRVO. Patients received either 0.5 mg of ranibizumab (n = 24) or 1.25 mg of bevacizumab (n = 56) intravitreally. Both groups received three initial monthly injections followed by as-needed injections. The best-corrected visual acuity, central subfield thickness, mean number of injections, and retreatment rate were evaluated monthly for 6 months after the initial injection.

RESULTS

The best-corrected visual acuity significantly improved from logarithm of the minimal angle of resolution (logMAR) 0.55 ± 0.26 at baseline to 0.24 ± 0.26 at 6 months in the ranibizumab group (p < 0.001) and from logMAR 0.58 ± 0.21 at baseline to 0.29 ± 0.25 at 6 months in the bevacizumab group (p < 0.001), which is not a statistically significant difference (p = 0.770). The mean reduction in central subfield thickness at 6 months was 236 ± 164 μm in the ranibizumab group (p < 0.001) and 219 ± 161 μm in the bevacizumab group (p < 0.001), which is not also a statistically significant difference (p = 0.698). The mean numbers of ranibizumab and bevacizumab injections were 3.25 ± 0.53 and 3.30 ± 0.53, respectively (p = 0.602). In addition, after the three initial monthly injections, the retreatment rates for ranibizumab and bevacizumab injections were 20.8% and 26.7%, respectively (p = 0.573).

CONCLUSIONS

Both ranibizumab and bevacizumab were effective for the treatment of BRVO and produced similar visual and anatomic outcomes. In addition, the mean number of injections and the retreatment rates were not significantly different between the groups.

MACULAR CHOROIDAL VOLUME CHANGES AFTER INTRAVITREAL BEVACIZUMAB FOR EXUDATIVE AGE-RELATED MACULAR DEGENERATION

PURPOSE

To evaluate the effect of intravitreal bevacizumab on the macular choroidal volume and the subfoveal choroidal thickness in treatment naïve eyes with exudative age-related macular degeneration.

METHODS

The macular choroidal volume and the subfoveal choroidal thickness were measured using enhanced depth imaging optical coherence tomography. After a screening examination, each patient received 3 monthly intravitreal injections of 1.25 mg bevacizumab. One month after the third injection was a final assessment.

RESULTS

Forty-seven patients with a mean age of 80 ± 6.4 years were included. The macular choroidal volume decreased significantly from median 4.1 mm (interquartile range 3.4-5.9) to median 3.9 mm (interquartile range 3.1-5.6) between the baseline and final examination (difference -0.46 mm, 95% confidence interval: -0.57 to 0.35, P < 0.001). Similarly, subfoveal choroidal thickness had decreased from 157.0 μm (interquartile range 116.0-244.5) at baseline to 139.0 μm (interquartile range 102.5-212.0) at the final examination (P < 0.001). Both parameters macular choroidal volume at baseline and subfoveal choroidal thickness at baseline were not associated with the response to treatment.

CONCLUSION

The macular choroidal volume and the subfoveal choroidal thickness decreased significantly after 3 monthly bevacizumab injections for exudative age-related macular degeneration.