Efficacy and Safety of Biosimilar FYB201 Compared with Ranibizumab in Neovascular Age-Related Macular Degeneration.

PURPOSE: This trial was conducted to investigate the clinical equivalence of the proposed biosimilar FYB201 and reference ranibizumab in patients with treatment-naive, subfoveal choroidal neovascularization caused by neovascular age-related macular degeneration (nAMD). DESIGN: This was a prospective, multicenter, evaluation-masked, parallel-group, 48-week, phase III randomized study. PARTICIPANTS: A total of 477 patients were randomly assigned to receive FYB201 (n = 238) or reference ranibizumab (n = 239). METHODS: Patients received FYB201 or reference ranibizumab 0.5 mg by intravitreal (IVT) injection in the study eye every 4 weeks. MAIN OUTCOME MEASURES: The primary end point was change from baseline in best-corrected visual acuity (BCVA) by Early Treatment Diabetic Retinopathy Study (ETDRS) letters at 8 weeks before the third monthly IVT injection. Biosimilarity of FYB201 to its originator was assessed via a 2-sided equivalence test, with an equivalence margin in BCVA of 3 ETDRS letters. RESULTS: The BCVA improved in both groups, with a mean improvement of +5.1 (FYB201) and +5.6 (reference ranibizumab) ETDRS letters at week 8. The analysis of covariance (ANCOVA) least squares mean difference for the change from baseline between FYB201 and reference ranibizumab was -0.4 ETDRS letters with a 90% confidence interval (CI) of -1.6 to 0.9. Primary end point was met as the 90% CI was within the predefined equivalence margin. Adverse events were comparable between treatment groups. CONCLUSIONS: FYB201 is biosimilar to reference ranibizumab in terms of clinical efficacy and ocular and systemic safety in the treatment of patients with nAMD.

Ocular Pharmacokinetics of Intravitreally Injected Protein Therapeutics: Comparison among Standard-of-Care Formats.

The current standard of care for antivascular endothelial growth factor (VEGF) treatment requires frequent intravitreal (IVT) injections of protein therapeutics, as a result of limited retention within the eye. A thorough understanding of the determinants of ocular pharmacokinetics (PK) and its translation across species is an essential prerequisite for developing more durable treatments. In this work, we studied the ocular PK in macaques of the protein formats that comprise today's anti-VEGF standard of care. Cynomolgus monkeys received a single IVT injection of a single-chain variable fragment (scFv, brolucizumab), antigen-binding fragment (Fab, ranibizumab), fragment crystallizable-fusion protein (Fc-fusion, aflibercept), or immunoglobulin G monoclonal antibody (IgG, VA2 CrossMAb). Drug concentrations were determined in aqueous humor samples collected up to 42 days postinjection using immunoassay methods. The ocular half-life (t1/2) was 2.28, 2.62, 3.13, and 3.26 days for scFv, Fab, Fc-fusion, and IgG, respectively. A correlation with human t1/2 values from the literature confirmed the translational significance of the cynomolgus monkey as an animal model for ocular research. The relation between ocular t1/2 and molecular size was also investigated. Size was inferred from the molecular weight (MW) or determined experimentally by dynamic light scattering. The MW and hydrodynamic radius were found to be good predictors for the ocular t1/2 of globular proteins. The analysis showed that molecular size is a determinant of ocular disposition and may be used in lieu of dedicated PK studies in animals.

Long-acting nanoparticle-loaded bilayer microneedles for protein delivery to the posterior segment of the eye.

Treatment of neovascular ocular diseases involves intravitreal injections of therapeutic proteins using conventional hypodermic needles every 4-6 weeks. Due to the chronic nature of these diseases, these injections will be administrated to patients for the rest of their lives and their frequent nature can potentially pose a risk of sight-threatening complications and poor patient compliance. Therefore, we propose to develop nanoparticle (NP)-loaded bilayer dissolving microneedle (MN) arrays, to sustain delivery of protein drugs in a minimally invasive manner. In this research, a model protein, ovalbumin (OVA)-encapsulated PLGA NPs were prepared and optimised using a water-in-oil-in-water (W/O/W) double emulsion method. The impact of stabilisers and primary sonication time on the stability of encapsulated OVA was evaluated using an enzyme-linked immunosorbent assay (ELISA). Results showed that the lower primary sonication time was capable of sustaining release (77 days at 28.5% OVA loading) and improving the OVA bioactivity. The optimised NPs were then incorporated into a polymeric matrix to fabricate bilayer MNs and specifically concentrated into MN tips by high-speed centrifugation. Optimised bilayer MNs exhibited good mechanical and insertion properties and rapid dissolution kinetics (less than 3 min) in excised porcine sclera. Importantly, ex vivo transscleral distribution studies conducted using a multiphoton microscope confirmed the important function of MN arrays in the localisation of proteins and NPs in the scleral tissue. Furthermore, the polymers selected to prepare bilayer MNs and OVA NPs were determined to be biocompatible with retinal cells (ARPE-19). This delivery approach could potentially sustain the release of encapsulated proteins for more than two months and effectively bypass the scleral barrier, leading to a promising therapy for treating neovascular ocular diseases.

Efficacy and Safety of a Proposed Ranibizumab Biosimilar Product vs a Reference Ranibizumab Product for Patients With Neovascular Age-Related Macular Degeneration: A Randomized Clinical Trial.

Importance: Neovascular age-related macular degeneration is the leading cause of blindness in individuals 50 years or older. The availability of a ranibizumab biosimilar product (SB11) may facilitate access to an effective alternative to this treatment. Objective: To demonstrate equivalence of efficacy, similar safety, and similar immunogenicity of SB11 compared with the reference ranibizumab. Design, Setting, and Participants: This randomized, double-masked, parallel-group phase 3 equivalence study was conducted in 75 centers in 9 countries from March 14, 2018, to December 9, 2019, among 705 participants 50 years or older with neovascular age-related macular degeneration with active subfoveal choroidal neovascularization lesions. Analysis was performed on an intent-to-treat basis. Interventions: Intravitreous injection of SB11 or ranibizumab, 0.5 mg, every 4 weeks through week 48. Main Outcomes and Measures: Preplanned interim analysis after all participants completed the week 24 assessment of primary efficacy end points at week 8 for change from baseline in best-corrected visual acuity (BCVA) and week 4 for central subfield thickness (CST), with predefined equivalence margins for adjusted treatment differences of -3 letters to 3 letters for BCVA and -36 µm to 36 µm for CST. Results: Baseline and disease characteristics among 705 randomized participants (403 women [57.2%]; mean [SD] age, 74.1 [8.5] years) were comparable between treatment groups (SB11, 351; ranibizumab, 354). Least-squares mean (SE) changes in BCVA from baseline at week 8 were 6.2 (0.5) letters in the SB11 group vs 7.0 (0.5) letters in the ranibizumab group, with an adjusted treatment difference of -0.8 letter (90% CI, -1.8 to 0.2 letters). Least-squares mean (SE) changes in CST from baseline at week 4 were -108 (5) µm in the SB11 group vs -100 (5) µm in the ranibizumab group, with an adjusted treatment difference of -8 µm (95% CI, -19 to 3 µm). Incidences of treatment-emergent adverse events (231 of 350 [66.0%] vs 237 of 354 [66.9%]), including serious treatment-emergent adverse events (44 of 350 [12.6%] vs 44 of 354 [12.4%]) and treatment-emergent adverse events leading to study drug discontinuation (8 of 350 [2.3%] vs 5 of 354 [1.4%]), were similar in the SB11 and ranibizumab groups. Immunogenicity was low, with a cumulative incidence of antidrug antibodies up to week 24 of 3.0% (10 of 330) in the SB11 group and 3.1% (10 of 327) in the ranibizumab group. Conclusions and Relevance: These findings of equivalent efficacy and similar safety and immunogenicity profiles compared with ranibizumab support the use of SB11 for patients with neovascular age-related macular degeneration. Trial Registration: ClinicalTrials.gov Identifier: NCT03150589.

REVIEW OF OPHTHALMIC AND BREASTFEEDING MEDICINE EVIDENCE: Real and Theoretical Risks of Intravitreal Anti-Vascular Endothelial Growth Factor Administration in Lactating Women.

BACKGROUND/PURPOSE: There is limited research regarding the consequences of treating lactating mothers with intravitreal anti-vascular endothelial growth factor (VEGF) agents. Balancing the need for vision-saving treatment, the benefits of breastfeeding, and the concern for affecting the newborn can present a conflict for both mothers and ophthalmologists. This review summarizes the state of the literature regarding the use of intravitreal anti-VEGF agents during breastfeeding along with details about their pharmacology. RESULTS: Bevacizumab and aflibercept have Fc domains subjecting them to FcRn recycling and extending their half-life compared with ranibizumab which is an antibody fragment and lacks the Fc domain. Case reports and small studies have shown that ranibizumab has the lowest serum concentration after intravitreal injection and the least effect on plasma-free VEGF concentrations and breastmilk VEGF levels. CONCLUSION: Clinical and pharmacologic data suggest that ranibizumab has less systemic circulation and effect on maternal serum and breastmilk VEGF levels when compared to bevacizumab and aflibercept. However, there is significant need for further research on the degree and duration to which intravitreal agents circulate systemically, what fraction is transferred into breastmilk and is absorbed, and whether this results in any functional adverse effects to the infant. Other factors to consider in the medical decision-making of lactating mothers necessitating intravitreal anti-VEGF treatment include the gestational and post-natal age of the child and whether it is feasible to avoid breastfeeding for the half-life duration of the intravitreal agent rather than ceasing breastfeeding altogether.

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 (MRT0-t ) by subretinal injection (11.57 ± 0.83 days) was significantly longer than the mean MRT0-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.

Non-invasive molecular tracking method that measures ocular drug distribution in non-human primates.

Intravitreal (IVT) injection has become the standard route for drug administration in retinal diseases. However, the ability to measure biodistribution of ocular therapeutics in large species remains limited, due to the invasive nature of some techniques or their lack of spatial information. The aim of this study was to develop in cynomolgus monkeys a non-invasive fluorescence imaging technology that enables tracking of IVT-dosed drugs and could be easily translated into humans. Here, we show a proof-of-concept for labeled ranibizumab with observed half-lives of 3.34 and 4.52 days at the retina and in the vitreous, respectively. We further investigate a long acting anti-VEGF antibody, which remains as an agglomerate with some material leaking out until the end of the study at Day 35. Overall, we were able to visualize and measure differences in the in vivo behavior between short and long-acting antibodies, demonstrating the power of the technology for ocular pharmacokinetics.

In Vitro Epiretinal Membrane Model and Antibody Permeability: Relationship With Anti-VEGF Resistance in Diabetic Macular Edema.

Purpose: Diabetic macular edema (DME) is characterized by an accumulation of fluid in the macula due to diabetic retinopathy. Currently, anti-VEGF drugs are the standard treatment worldwide for DME. This study aimed to assess whether the existence of epiretinal membrane (ERM) affects anti-VEGF efficacy, due to reduced permeability of the antibody through the ERM. Methods: We retrospectively examined clinical data of DME patients who underwent anti-VEGF treatment and evaluated whether clinical differences existed between DME eyes with ERM and those without ERM. We then created an in vitro ERM model using MIO-M1, ARPE-19, and NTI-4 cells on Transwell membranes and evaluated antibody permeability through this in vitro ERM model using fluorescently labeled antibodies. Results: Central retinal thickness (CRT) change between before and 1 month after first anti-VEGF treatment, as well as final CRT and final visual acuity 12 months after first anti-VEGF treatment, significantly differed between DME eyes with ERM and those without ERM. The in vitro ERM model led to production of collagen I in a manner similar to that of human ERM specimens. Fluorescence intensity of the lower chamber of the in vitro ERM model was significantly reduced in a dose-dependent manner. Conclusions: Clinical data analysis indicated that the existence of ERM in DME eyes lowered the efficacy of anti-VEGF treatment. Reduced antibody permeability through the in vitro ERM model suggested ERM presence was associated with resistance to anti-VEGF treatment in DME eyes with ERM.

Nephrotoxicity induced by intravitreal vascular endothelial growth factor inhibitors: emerging evidence.

Vascular endothelial growth factor (VEGF) inhibitors have emerged as powerful tools to treat malignant neoplasms and ocular diseases by virtue of their ability to inhibit angiogenesis. Recent data indicate that intravitreal injections of VEGF inhibitors can lead to significant systemic absorption as well as a measurable reduction of plasma VEGF activity. There is increasing evidence showing that vitreal absorption of these drugs is associated with cases of accelerated hypertension, worsening proteinuria, glomerular disease, thrombotic microangiopathy, and possible chronic renal function decline. In this review, the 3 most commonly used anti-VEGF agents-bevacizumab, ranibizumab, and aflibercept-are discussed, highlighting their intravitreal absorption and associated effects on the kidney as a target organ system. We provide clinical suggestions for clinicians to both better manage patients receiving anti-VEGF agents intravitreally and detect any putative systemic renal effects of these agents. While acknowledging the risks of aberrant retinal angiogenesis, it is important for clinicians to be aware of the potential for adverse renal risks with use of these agents.

Three-Dimensional Transport Model for Intravitreal and Suprachoroidal Drug Injection.

Purpose: Quantitative understanding of the transport of therapeutic macromolecules following intraocular injections is critical for the design of efficient strategies in treating eye diseases, such as neovascular (wet) age-related macular degeneration (AMD) and macular edema (ME). Antiangiogenic treatments, such as neutralizing antibodies against VEGF or recently characterized antiangiogenic peptides, have shown promise in slowing disease progression. Methods: We developed a comprehensive three-dimensional (3D) transport model for intraocular injections using published data on drug distribution in rabbit eyes following intravitreal and suprachoroidal (SC) injection of sodium fluorescein (SF), bevacizumab, and ranibizumab. The model then was applied to evaluate the distribution of small molecules and antiangiogenic proteins following intravitreal and SC injections in human eyes. Results: The model predicts that intravitreally administered molecules are substantially mixed within the vitreous following injection, and that the long-term behavior of the injected drug does not depend on the initial mixing. Ocular pharmacokinetics of different drugs is sensitive to different clearance mechanisms. Effective retinal drug delivery is impacted by RPE permeability. For VEGF antibody, intravitreal injection provides sustained delivery to the retina, whereas SC injection provides more efficient, but short-lived, retinal delivery for smaller-sized molecules. Long-term suppression of neovascularization through SC administration of antiangiogenic drugs necessitates frequent injection or sustained delivery, such as microparticle-based delivery of antiangiogenic peptides. Conclusions: A comprehensive 3D model for intravitreal and SC drug injection is developed to provide a framework and platform for testing drug delivery routes and sustained delivery devices for new and existing drugs.

Photokinetic Drug Delivery: Near infrared (NIR) Induced Permeation Enhancement of Bevacizumab, Ranibizumab and Aflibercept through Human Sclera.

PURPOSE: Permeation studies, with near infrared (NIR) light and anti-aggregation antibody formulation, were used to investigate the in vitro permeation of bevacizumab, ranibizumab and aflibercept through human sclera. METHODS: A vertical, spherical Franz cell diffusion apparatus was used for this scleral tissue permeation model. A photokinetic ocular drug delivery (PODD) testing device accommodated the placement of NIR LEDs above the donor chambers. An adjustable LED driver/square wave generator provided electrical energy with a variable pulse rate and pulse width modulation (duty cycle). RESULTS: Exposure to non-thermal NIR light had no effect on mAbs with regard to monomer concentration or antibody binding potential, as determined by SE-HPLC and ELISA. The optimal LED wavelength was found to be 950 nm. Duty cycle power of 5% vs 20% showed no difference in permeation. When compared to controls, the combination of non-aggregating antibody formulation and NIR illumination provided an average transscleral drug flux enhancement factor of 3X. CONCLUSION: Narrow wavelength incoherent (non-laser) light from an NIR LED source is not harmful to mAbs and can be used to enhance drug permeation through scleral tissue. The topical formulation, combined with pulsed NIR light irradiation, significantly improved scleral permeation of three anti-VEGF antibody drugs.

[Systemic safety following intravitreal injections of anti-VEGF]. / Tolérance systémique des injections intravitréennes d'anti-VEGF.

The goal of this manuscript is to assess data suggesting that intravitreal injection of anti-vascular endothelial growth factors (anti-VEGFs) could result in systemic adverse events (AEs). The class-specific systemic AEs should be similar to those encountered in cancer trials. The most frequent AE observed in oncology, hypertension and proteinuria, should thus be the most common expected in ophthalmology, but their severity should be lower because of the much lower doses of anti-VEGFs administered intravitreally. Such AEs have not been frequently reported in ophthalmology trials. In addition, pharmacokinetic and pharmacodynamic data describing systemic diffusion of anti-VEGFs should be interpreted with caution because of significant inconsistencies reported. Thus, safety data reported in ophthalmology trials and pharmacokinetic/pharmacodynamic data provide robust evidence that systemic events after intravitreal injection are very unlikely. Additional studies are needed to explore this issue further, as much remains to be understood about local and systemic side effects of anti-VEGFs.

Systemic Biodistribution and Intravitreal Pharmacokinetic Properties of Bevacizumab, Ranibizumab, and Aflibercept in a Nonhuman Primate Model.

Purpose: To determine the intravitreal pharmacokinetic properties and to study the systemic biodistribution characteristics of I-124-labeled bevacizumab, ranibizumab, and aflibercept with positron emission tomography-computed tomography (PET/CT) imaging in a nonhuman primate model. Methods: Three groups with four owl monkeys per group underwent intravitreal injection with 1.25 mg/0.05 mL I-124 bevacizumab, 0.5 mg/0.05 mL I-124 ranibizumab, or 2.0 mg/0.05 mL I-124 aflibercept in the right eye of each subject. All subjects were imaged using PET/CT on days 0, 1, 2, 4, 8, 14, 21, 28, and 35. Serum blood draws were performed at hours 1, 2, 4, 8, 12 and days 1, 2, 4, 8, 14, 21, 28, and 35. Radioactivity emission measurements were used to determine the intravitreal half-lives of each agent and to study the differences of radioactivity uptake in nonocular organs. Results: The intravitreal half-lives were 3.60 days for I-124 bevacizumab, 2.73 days for I-124 ranibizumab, and 2.44 days for I-124 aflibercept. Serum levels were highest and most prolonged for bevacizumab as compared to both ranibizumab and aflibercept. All agents were primarily excreted through the renal and mononuclear phagocyte systems. However, bevacizumab was also found in significantly higher levels in the liver, heart, and distal femur bones. Conclusions: Among the three anti-VEGF agents used in clinical practice, bevacizumab demonstrated the longest intravitreal retention time and aflibercept the shortest. Significantly higher and prolonged levels of bevacizumab were found in the serum as well as in the heart, liver, and distal bones. These differences may be considered by clinicians when formulating treatment algorithms for intravitreal therapies with these agents.

[Clinical associations between photoreceptor status and visual outcomes in diabetic macular edema]. / Klinicheskie paralleli sostoyaniya fotoretseptorov setchatki i vosstanovleniya zritel'nykh funktsii pri diabeticheskom makulyarnom oteke.

AIM: to investigate morphological changes and visual acuity response to ranibizumab therapy in patients with different OCT-types of diabetic macular edema (DME) as well as different state of the inner and outer photoreceptor segments (IS and OS) and the outer limiting membrane (OLM); to study relationships between functional and morphological parameters before and after the treatment; to study the effect of glycated hemoglobin levels on morphological parameters and ME duration. MATERIAL AND METHODS: The study included 113 patients (113 eyes) with DME, who underwent 3 once-monthly intravitreal injections of ranibizumab (the mean patient age, 63.5±2.2 years; men, 51.3%; type 2 diabetes, 81.4%). Basing on the results of OCT, 3 groups were formed: group 1 (40 patients) - intact IS and OS; group 2 (32 patients) - disturbed photoreceptor segments integrity, but intact OLM; group 3 (41 patients) - destruction of both layers. RESULTS: Visual acuity at baseline and after the treatment was the highest in group 1 (p<0.05). In all groups, most parameters that indicated the state of photoreceptor segments and the OLM improved. Correlation analysis revealed a statistically significant negative correlation between visual acuity at baseline and after the treatment and morphological parameters (p<0.05). There was also a direct correlation between the morphometric parameters at baseline and after the treatment (p<0.05). The most favorable type of DME in terms of preserving the integrity of photoreceptor segments and the OLM was sponge-like edema, while DME with neuroepithelial detachment and mixed-type DME were prognostically unfavorable. Moreover, the state of photoreceptors and the OLM depended on the duration of ME and the level of glycated hemoglobin. Thus, the integrity of the inner and outer photoreceptor segments as well as the outer limiting membrane can contribute to prognosis for functional outcomes in DME patients that receive antiangiogenic therapy.

Long-acting protein drugs for the treatment of ocular diseases.

Protein drugs that neutralize vascular endothelial growth factor (VEGF), such as aflibercept or ranibizumab, rescue vision in patients with retinal vascular diseases. Nonetheless, optimal visual outcomes require intraocular injections as frequently as every month. Here we report a method to extend the intravitreal half-life of protein drugs as an alternative to either encapsulation or chemical modifications with polymers. We combine a 97-amino-acid peptide of human origin that binds hyaluronan, a major macromolecular component of the eye's vitreous, with therapeutic antibodies and proteins. When administered to rabbit and monkey eyes, the half-life of the modified proteins is increased ∼3-4-fold relative to unmodified proteins. We further show that prototype long-acting anti-VEGF drugs (LAVAs) that include this peptide attenuate VEGF-induced retinal changes in animal models of neovascular retinal disease ∼3-4-fold longer than unmodified drugs. This approach has the potential to reduce the dosing frequency associated with retinal disease treatments.

SYSTEMIC PHARMACOKINETICS AND PHARMACODYNAMICS OF INTRAVITREAL AFLIBERCEPT, BEVACIZUMAB, AND RANIBIZUMAB.

PURPOSE: To evaluate the systemic pharmacokinetics (PKs) of aflibercept, bevacizumab, and ranibizumab in patients with neovascular age-related macular degeneration (AMD), diabetic macular edema (DME), or retinal vein occlusion (RVO). METHODS: Prospective, open-label, nonrandomized clinical trial of patients with AMD, DME, or RVO who were antivascular endothelial growth factor (VEGF) naïve or had not received anti-VEGF for ≥4 months. Patients received 3 monthly intravitreal injections of aflibercept 2.0 mg, bevacizumab 1.25 mg, or ranibizumab (0.5 mg for AMD/RVO, 0.3 mg for DME). The main outcome measures were serum PKs and plasma free-VEGF concentrations after the first and third injections. RESULTS: A total of 151 patients were included. In AMD/DME/RVO, systemic exposure to each drug was highest with bevacizumab, then aflibercept, and lowest with ranibizumab. Ranibizumab cleared from the bloodstream more quickly than bevacizumab or aflibercept. Aflibercept treatment resulted in the greatest reductions in plasma free-VEGF relative to baseline levels, whereas ranibizumab treatment resulted in the smallest decreases in plasma free-VEGF. CONCLUSION: The three anti-VEGF treatments examined in this analysis demonstrated notable differences in systemic PKs. Generally, the reduction in plasma free-VEGF levels correlated with elevated levels of circulating anti-VEGF agents, with the reduction in free-VEGF levels greatest with aflibercept and least with ranibizumab.

Ranibizumab interacts with the VEGF-A/VEGFR-2 signaling pathway in human RPE cells at different levels.

Vascular endothelial growth factor (VEGF) secreted by the retinal pigment epithelium (RPE) plays an important role in ocular homeostasis, but also in diseases, most notably age-related macular degeneration (AMD). To date, anti-VEGF drugs like ranibizumab have been shown to be most effective in treating these pathologic conditions. However, clinical trials suggest that the RPE could degenerate and perish through anti-VEGF treatment. Herein, we evaluated possible pathways and outcomes of the interaction between ranibizumab and human RPE cells (ARPE-19). Results indicate that ranibizumab affects the VEGF-A metabolism in RPE cells from an extra- as well as intracellular site. The drug is taken up into the cells, with the VEGF receptor 2 (VEGFR-2) being involved, and decreases VEGF-A protein levels within the cells as well as extracellularly. Oxidative stress plays a key role in various inflammatory disorders of the eye. Our results suggest that oxidative stress inhibits RPE cell proliferation. This anti-proliferative effect on RPE cells is significantly enhanced through ranibizumab, which does not inhibit RPE cell proliferation substantially in absence of relevant oxidative stress. Therefore, we emphasize that anti-VEGF treatment should be selected carefully in AMD patients with preexistent extensive RPE atrophy.

Vascular Endothelial Growth Factor (VEGF) Concentration Is Underestimated by Enzyme-Linked Immunosorbent Assay in the Presence of Anti-VEGF Drugs.

PURPOSE: Commercially available enzyme-linked immunosorbent assay (ELISA) kits are often used to monitor vascular endothelial growth factor (VEGF) levels in exudative age-related macular degeneration. To test their accuracy, this study performed measurements using the ELISA kits in the presence of anti-VEGF drugs. METHODS: The concentrations of bevacizumab, pegaptanib, or ranibizumab at 28 days and aflibercept at 28 and 56 days after an injection were estimated based on previous pharmacokinetic studies. Vascular endothelial growth factor concentrations were measured with two widely used VEGF ELISA kits in the presence of anti-VEGF drugs or control mouse immunoglobulin G (IgG). The monocyte chemotactic protein-1 (MCP-1) ELISA kit was used as a non-VEGF ELISA control kit. RESULTS: The concentrations of aflibercept, bevacizumab, pegaptanib, and ranibizumab were estimated at 0.14 to 7.2, 4.9, 8.6, and 0.11 to 1.1 µg/mL, respectively. ELISA underestimated the VEGF concentration 2- to 100-fold lower in the presence of an anti-VEGF drug, except for pegaptanib, at all VEGF concentrations tested (7.8-1500 pg/mL). Vascular endothelial growth factor at 1000 pg/mL was measured as 92, 150, and 170 pg/mL in the presence of aflibercept (7.2 µg/mL), bevacizumab (4.9 µg/mL), and ranibizumab (1.1 µg/mL), respectively (all P < 0.0001), and the measured VEGF concentration decreased proportionately by 90% to 92% with aflibercept, 85% to 94% with bevacizumab, and 83% to 99% with ranibizumab. The control mouse IgG did not interfere with the measurement of VEGF. Ranibizumab did not affect the measurements with MCP-1 ELISA. CONCLUSIONS: Investigators should exercise caution when interpreting measurements of VEGF ELISA in patients being treated with an anti-VEGF drug.