Intraocular neutralizing antibodies against aflibercept in patients with age related macular degeneration

Nonclinical study of ixo-vec gene therapy for nAMD supports efficacy for a human dose of 6E10 vg/eye and staggered dosing of fellow eyes

Ixoberogene soroparvovec (ixo-vec), formerly ADVM-022, is an adeno-associated virus (AAV) gene therapy using the AAV.7m8 capsid for intravitreal delivery (IVT) to transduce retinal tissue and produce sustained intraocular aflibercept for treating neovascular age-related macular degeneration (nAMD). Non-clinical studies show that aflibercept production by ixo-vec is less than dose proportional, while intraocular inflammation (IOI) increases with dose, suggesting that lower doses could yield effective aflibercept levels with reduced IOI risk. Our evaluation confirmed that doses as low as 3E10 vg (vector genome)/eye (6E10 vg/eye human equivalent) maintained effective aflibercept production. The concept behind ADVM-022 is supported by clinical studies OPTIC (NCT03748784) and LUNA (NCT05536973), where a single IVT administration eliminated or significantly reduced the need for additional anti-VEGF injections in patients. Moreover, LUNA confirmed the clinical efficacy of a 6E10-vg/eye dose, demonstrating robust and sustained aflibercept levels. Additionally, we evaluated staggered dosing in contralateral eyes to treat asynchronous disease development. Staggered dosing, administered 2 months apart, did not exacerbate IOI, and both eyes maintained therapeutic aflibercept levels. These findings support the tolerability and efficacy of staggered dosing, indicating the potential for bilaterally relevant aflibercept levels with ixo-vec, due to immune response confinement to the dosed eye.

Comparative Pharmacokinetic Analysis of Aflibercept and Brolucizumab in Human Aqueous Humor Using Nano-Surface and Molecular-Orientation Limited Proteolysis

Aflibercept and brolucizumab, two anti-VEGF agents used as intravitreal injections in ophthalmology, differ significantly in molecular weight (aflibercept-115 kDa and brolucizumab-26 kDa). Using aqueous humor samples collected after drug administration, we measured and performed a comparative analysis of pharmacokinetics and half-lives of these drugs in the human eye. Since the quantification of monoclonal antibodies (mAbs) using antigen-antibody reactions, such as ELISA, is influenced by endogenous ligands or anti-drug antibodies, we employed nano-surface and molecular-orientation limited proteolysis (nSMOL), combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS), for accurate measurements. Aqueous humor samples were collected from 59 eyes of 59 patients treated with aflibercept and 52 eyes of 52 patients treated with brolucizumab. Samples were obtained with a median post-injection period of 30 (range, 2-49) days for aflibercept and 28 (range, 4-60) days for brolucizumab. A population pharmacokinetic (PPK) analysis revealed that the half-life of aflibercept in human aqueous humor was significantly shorter than that of brolucizumab, 2.88 days versus 9.00 days, respectively (p = 1.16 × 10-7). Using the same mass spectrometry conditions, we calculated the half-lives of the two drugs. These results may be useful for optimizing the efficacy of these drugs in clinical practice.

Conversion to faricimab after prior anti-vascular endothelial growth factor therapy for persistent diabetic macular oedema

BACKGROUND

To assess the anatomical and functional outcomes in eyes with persistent diabetic macular oedema (pDME) on chronic anti-vascular endothelial growth factor therapy switched to intravitreal faricimab.

METHODS

Patients with pDME on chronic anti-vascular endothelial growth factor therapy that were switched to faricimab and received at least three injections at our institution between April 2022 and May 2023 were included in this study. Patients were excluded if they had complete response to previous treatment but were switched to extend treatment intervals if they had steroid or laser treatment for DME within 6 months prior to switch. Clinical and imaging data were extracted from the electronic medical record. Central foveal thickness (CFT) and Snellen visual acuity (VA) were obtained before and after three intravitreal faricimab injections. Generalised estimating equations were used to analyse the change in CFT and VA.

RESULT

During the study period, 69 eyes of 53 patients met inclusion criteria. The mean age was 68.6±9.0 years. The mean number of injections prior to switch was 18.1±16.0. Pre-switch mean logarithm of the minimal angle of resolution VA was 0.40±0.30 (Snellen equivalent 20/50) and 0.38±0.27 (Snellen equivalent 20/48) after three faricimab injections (p=0.397). Mean CFT improved from 380±155 microns to 323±147 microns (p<0.001). No ophthalmic or systemic adverse events occurred during the study period.

CONCLUSIONS

Intravitreal faricimab can improve anatomic outcomes while maintaining visual acuity in eyes with pDME previously treated with anti-VEGF therapy.

Gene therapy for age-related macular degeneration: potential, feasibility, and pitfalls

PURPOSE OF REVIEW

The landscape for age-related macular degeneration (AMD) is rapidly changing with addition of biosimilars and now United States Food and Drug Administration (FDA) approved nonneovascular AMD (nnAMD) treatment options. These developments have inspired a burgeoning pipeline of gene therapy approaches focused on similar antivascular endothelial growth factors (VEGF) and complement related pathways. Historic and more recent setbacks in the gene therapy pipeline, including intraocular inflammatory reactions, have raised important concerns for adverse events related to AMD therapeutics both for gene and nongene approaches. The specific clinical profile of these therapeutics approaching later stage clinical trials are complex and under active investigation; however, these options hold promise to disrupt the current landscape and change management paradigms for one of the leading causes of vision loss worldwide.

RECENT FINDINGS

This review covers current gene therapy approaches for neovascular AMD (nAMD) and nnAMD. Intravitreal, suprachoroidal, and subretinal delivery routes are discussed with attention to technical procedure, capabilities for transgene delivery to target tissue, immunogenicity, and collateral effects. Suprachoroidal delivery is an emerging approach which may bridge some of the practical drawbacks for intravitreal and subretinal methods, though with less elaborated immunologic profile. In parallel to delivery modification, viral vectors have been cultivated to target specific cells, with promising enhancements in adeno-associated viral (AAV) vectors and persistent interest in alternate viral and nonviral delivery vectors. Ongoing questions such as steroid or immunosuppressive regimen and economic considerations from a payer and societal perspective are discussed.

SUMMARY

The present review discusses emerging gene therapy options which could foster new, more durable nAMD and nnAMD therapeutics. These options will need refinement with regards to route, vector, and dosage, and specialists must decipher the specific clinical risk benefit profile for individual patients. Ongoing concerns for immunogenicity or dosage related adverse events could stifle progress, while further vector development and refined delivery techniques have the potential to change the safety and efficacy of currently options in the pipeline.