Bioanalysis Zone

Development and evaluation of an ultrasensitive free VEGF-A immunoassay for analysis of human aqueous humor

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Aim: Novel bifunctional vascular endothelial growth factor A (VEGF-A) neutralizing therapies are being developed for the treatment of retinal vascular diseases such as age-related macular degeneration and diabetic retinopathy. In developing new therapeutic drugs, only small aqueous humor sample volumes are available for analyzing several parameters. Highly sensitive detection methods must be applied in analyzing VEGF-A levels in ocular fluids in order to demonstrate VEGF-A suppression following drug administration. Experimental: A highly sensitive immunoassay for VEGF-A was developed on the single molecule array (Simoa) platform, and validated before being used for the analysis of clinical aqueous humor samples from patients treated with anti-VEGF-A therapeutics. Results: This highly sensitive immunoassay allows the detection of baseline VEGF-A levels and suppression effects after drug administration, even in sample volumes as low as 12 μl. Conclusion: The Simoa VEGF-A assay is a valuable tool for the reliable monitoring of VEGF-A suppression after intravitreal administration of anti-VEGF-A drugs.

Key words: aqueous humor, biomarker, diabetic macular edema, faricimab, immunoassay, ophthalmology, single molecule array, soluble target, VA2 Cross Mab, vascular endothelial growth factor A


Choroidal neovascular eye diseases, such as diabetic macular edema (DME), diabetic retinopathy or wet age-related macular degeneration (wAMD), are caused by abnormal leakage and neovascularization of retinal vessels and are the major causes of visual impairment worldwide [1–3]. In recent years, anti-VEGF-A drug treatments [4] have dramatically improved the prognosis in patients with neovascular age-related macular degeneration (nvAMD) or DME and have become standard treatment [5,6]. In clinical studies, visual acuity is usually considered to be the primary efficacy end point. In addition, aqueous humor (AH) offers further relevant parameters, with VEGF-A being one of the most notable analytes [7].

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