A mechanism-based model for the population pharmacokinetics of free and bound aflibercept in healthy subjects

Comparison of the efficacy and safety of SCD411 and reference aflibercept in patients with neovascular age-related macular degeneration

To compare the efficacy and safety of the proposed aflibercept biosimilar SCD411 and reference aflibercept in patients with neovascular age-related macular degeneration, this randomized, double-masked, parallel-group, multicenter study was conducted in 14 countries from 13 August 2020 to 8 September 2022. Patients with neovascular age-related macular degeneration. With subfoveal, juxtafoveal, or extrafoveal choroidal neovascularization were aged 50 years or older. Intravitreal injection of SCD411 or aflibercept (2.0 mg) were administered every 4 weeks for the first three injections and every 8 weeks until week 48. The primary efficacy endpoint was the change in best-corrected visual acuity from baseline to week 8 with an adjusted equivalence margin of ± 3.0 letters. Patients were randomly assigned to receive either SCD411 (n = 288) or reference aflibercept (n = 288). A total of 566 participants (98.3%) completed week 8 of the study. The least-squares mean difference of change in best-corrected visual acuity from baseline to week 8 (SCD411-aflibercept) was - 0.4 letters (90% confidence interval =  - 1.6 to 0.9). The incidence of ocular (69 of 287 [24.0%] vs. 71 of 286 [24.8%]) and serious ocular (5 of 287 [1.7%] vs. 3 of 286 [1.0%]) treatment-emergent adverse effects were similar between the SCD411 and aflibercept groups. Immunogenicity analysis revealed a low incidence of neutralizing antibody formation in both groups. In conclusion, SCD411 has equivalent efficacy compared with reference aflibercept in patients with neovascular age-related macular degeneration and has a comparable safety profile. The results support the potential use of SCD411 for the treatment of neovascular age-related macular degeneration.

A novel LC-MS/MS approach to the pharmacokinetic study of free and bound aflibercept simultaneously

To comprehensively evaluate the pharmacokinetic (PK) characteristics of aflibercept, we established a liquid chromatography with tandem mass spectrometry (LC-MS/MS) method to determine the concentration of vascular endothelial growth factor (VEGF)-A-bound aflibercept and free aflibercept. A specific sample preparation method of nano-surface and molecular-orientation limited (nSMOL) proteolysis was performed to extract both free and bound aflibercept from plasma. The tryptic peptides unique to aflibercept and VEGF-A were selected to quantify the amounts of total aflibercept and aflibercept-VEGF complex, respectively. The method was validated by evaluating its selectivity, linearity, precision, accuracy, extraction recovery, matrix effect, and stability. It was then successfully used to quantify total and bound aflibercept concentrations in cynomolgus monkey plasma, while indirectly obtaining the concentration of free aflibercept by subtraction. The PK results of this LC-MS/MS method are comparable to the traditional enzyme-linked immunosorbent assay (ELISA) results. It is thus a reliable and complementary method for the PK evaluation of aflibercept. Graphical abstract.

Utility of free and total target measurements as target engagement and efficacy biomarkers in biotherapeutic development--opportunities and challenges

For biotherapeutics directed against soluble targets, most often monoclonal antibodies (mAbs), their therapeutic efficacy theoretically is driven by the magnitude and duration of free target suppression. However, for soluble targets of rapid turnover and low abundance, it can be technically challenging to directly measure the lowering of free target following treatment with biologics. The opportunities, challenges, and practical approaches to assess free and bound soluble targets and the utility of free and bound target measurements as biomarkers for target engagement and efficacy are covered in this review. In particular, case examples are presented to illustrate the interplay between drug and free/bound target, and how an integrated bioanalytical and pharmacokinetic/target engagement/pharmacodynamic (PK/TE/PD) modeling approach can be used to assess the target engagement for biologics directed against soluble targets with rapid turnover. Important caveats of the modeling approach in the absence of free target measurements are also discussed.

Treatment of Exudative Age-related Macular Degeneration: Focus on Aflibercept

A formulation of aflibercept for intravitreal injection (Eylea) is approved for the treatment of patients with exudative age-related macular degeneration (AMD). Aflibercept has a significantly higher affinity for Vascular endothelial growth factor (VEGF)-A compared with other monoclonal anti-VEGF antibodies. In addition to binding all VEGF-A isoforms, aflibercept also blocks other proangiogenic factors such as VEGF-B and placental growth factor. The VIEW 1 and 2 trials showed this drug achieves improved results in patients with exudative AMD similar to those obtained with monthly ranibizumab, using a bimonthly treatment regimen after a loading dose of three intravitreal injections, which translates to less use of healthcare resources. There is a subgroup of patients that present with persistent fluid after the loading dose that could benefit from monthly injections or personalized proactive treatment after the first year. In the second year of treatment, the Treat and Extend patterns can permit even more lengthening of the time between injections. More data are needed to confirm the optimal monitoring and retreatment dosing, to maintain long-term efficacy. Other preliminary data suggest that patients that do not respond to other anti-angiogenics and patients with special pathologies such as polypoidal choroidopathy or retinal angiomatous proliferation can improve upon switching to aflibercept. To date, the safety profile of aflibercept is excellent and is comparable to other anti-angiogenic treatments.

A Tutorial on Target-Mediated Drug Disposition (TMDD) Models

Target-mediated drug disposition (TMDD) is the phenomenon in which a drug binds with high affinity to its pharmacological target site (such as a receptor) to such an extent that this affects its pharmacokinetic characteristics.1 The aim of this Tutorial is to provide an introductory guide to the mathematical aspects of TMDD models for pharmaceutical researchers. Examples of Berkeley Madonna2 code for some models discussed in this Tutorial are provided in the Supplementary Materials.

Vascular endothelial growth factor trap-eye and trap technology: Aflibercept from bench to bedside

Anti-vascular endothelial growth factor (VEGF) currently used to treat eye diseases have included monoclonal antibodies, antibody fragments, and an aptamer. A different method of achieving VEGF blockade in retinal diseases includes the concept of a cytokine trap. Cytokine traps technology are being evaluated for the treatment of various diseases that are driven by excessive cytokine levels. Traps consist of two extracellular cytokine receptor domains fused together to form a human immunoglobulin G (IgG). Aflibercept/VEGF trap-eye (VTE) is a soluble fusion protein, which combines ligand-binding elements taken from the extracellular components of VEGF receptors 1 and 2 fused to the Fc portion of IgG. This protein contains all human amino acid sequences, which minimizes the potential for immunogenicity in human patients. This review presents the latest data on VTE in regard to the pharmacokinetics, dosage and safety, preclinical and clinical experiences. Method of the literature search: A systematic search of the literature was conducted on PubMed, Scopus, and Google Scholar with no limitation on language or year of publication databases. It was oriented to articles published for VTE in preclinical and clinical studies and was focused on the pharmacokinetics, dosage and safety of VTE.

What is the evidence for systemic effects of intravitreal anti-VEGF agents, and should we be concerned?

Anti-vascular endothelial growth factor (VEGF) therapy has revolutionised the treatment of retinal disease, and appears to be very safe. Nevertheless, there are several lines of evidence that imply that small doses of these agents could potentially have a systemic effect. The clinical significance of these systemic effects remains unclear, but further study is indicated.

Mechanistic pharmacokinetic/target engagement/pharmacodynamic (PK/TE/PD) modeling in deciphering interplay between a monoclonal antibody and its soluble target in cynomolgus monkeys

For therapeutic monoclonal antibodies (mAbs) against soluble ligands, the free ligand level can, theoretically, be used as a surrogate for efficacy. However, it can be extremely challenging technically to measure free ligand level in the presence of an excessive amount of antibody-ligand complex. The interplay among such mAbs, ligands, and the downstream pharmacodynamic (PD) effects has not been well defined. Using siltuximab and interleukin-6 (IL-6) as model compounds, a pharmacokinetic (PK)/target engagement (TE) model was established via simultaneous fitting of total siltuximab, total IL-6, and free IL-6 concentration profiles following a low dose of siltuximab in cynomolgus monkeys. The model adequately captured the observed data and provided estimation of model parameters with good precision. The PK/TE model was used to predict free IL-6 profiles at higher siltuximab doses, where the accurate determination of free IL-6 concentration became technically too difficult. The measured free IL-6 levels from the low-dose groups and PK/TE model-predicted free IL-6 levels from the high-dose groups were used to drive an indirect response TE/PD model to describe the concentration-effect relationship between free IL-6 and C-reactive protein (CRP). The TE/PD model adequately captured both CRP elevation and CRP suppression in response to free IL-6 concentration change from baseline with a linear stimulation function, providing direct evidence that the PK/TE model-predicted free IL-6 levels from the high-dose groups were accurate. Overall, the results provided an integrated PK/TE/PD modeling and bioanalytical framework for prediction of efficacious dose levels and duration of action for mAbs against soluble ligands with rapid turnover.

Development of a preclinical PK/PD model to assess antitumor response of a sequential aflibercept and doxorubicin-dosing strategy in acute myeloid leukemia

Timing of the anti-angiogenic agent with respect to the chemotherapeutic agent may be crucial in determining the success of combination therapy in cancer. We investigated the effects of sequential therapy with the potent VEGF inhibitor, aflibercept, and doxorubicin (DOX) in preclinical acute myeloid leukemia (AML) models. Mice were engrafted with human HL-60 and HEL-luciferase leukemia cells via S.C. and/or I.V. injection and treated with two to three doses of aflibercept (5-25 mg/kg) up to 3-7 days prior to doxorubicin (30 mg/kg) administration. Leukemia growth was determined by local tumor measurements (days 0-16) and systemic bioluminescent imaging (days 0-28) in animals receiving DOX (3 mg/kg) with or without aflibercept. A PK/PD model was developed to characterize how prior administration of aflibercept altered intratumoral DOX uptake. DOX concentration-time profiles were described using a four-compartment PK model with linear elimination. We determined that intratumoral DOX concentrations were 6-fold higher in the aflibercept plus DOX treatment group versus DOX alone in association with increased drug uptake rates (from 0.125 to 0.471 ml/h/kg) into tumor without affecting drug efflux. PD modeling demonstrated that the observed growth retardation was mainly due to the combination of DOX plus TRAP group; 0.00794 vs. 0.0043 h(-1). This PK/PD modeling approach in leukemia enabled us to predict the effects of dosing frequency and sequence for the combination of anti-VEGF and cytotoxic agents on AML growth in both xenograft and marrow, and may be useful in the design of future rational combinatorial dosing regimens in hematological malignancies.

Aflibercept: a Potent Vascular Endothelial Growth Factor Antagonist for Neovascular Age-Related Macular Degeneration and Other Retinal Vascular Diseases

Introduction

In the western hemisphere, age-related macular degeneration (AMD) is the leading cause of visual loss in the elderly. Currently approved therapies for AMD include argon laser, photodynamic therapy, and antivascular endothelial growth factor (VEGF) therapy. The index review discusses aflibercept (VEGF Trap-Eye) in the context of current anti-VEGF therapies for neovascular AMD and other retinal vascular diseases. It highlights important differences between VEGF Trap-Eye and currently used anti-VEGF therapies for neovascular AMD; and discusses the efficacy of these treatments utilizing information from landmark clinical trials.

Methods

A systematic search of literature was conducted on PubMed, Science Direct, and Scopus with no limitations of language or years of publication.

Results

Preclinical studies have shown that VEGF Trap-Eye binds to VEGF-A with a higher affinity than other anti-VEGF molecules; and that it also binds to placental growth factor (PlGF). In clinical trials, VEGF Trap-Eye has been shown to be as effective in the treatment of neovascular AMD as other anti-VEGF therapies and possibly to have a longer duration of drug activity.

Conclusion

VEGF Trap-Eye has enhanced the treatment options currently available for the management of neovascular AMD. The comparable efficacy of VEGF Trap-Eye (to other anti-VEGF agents) coupled with its longer dosing interval may decrease the number of annual office visits for patients with AMD and their caregivers.