Author’s Disclosure Block: Andrew Mihalache: none; Ryan Huang: none; Marko Popovic: Financial support (to institution) – PSI Foundation, Fighting Blindness Canada.; Sue Demian: none; Rajeev Muni: Consultant – Alcon, Apellis, AbbVie, Bayer, Bausch Health, Roche; Financial Support (to institution) – Alcon, AbbVie, Bayer, Novartis, Roche.

Abstract Body
Purpose: The critical role of vascular endothelial growth factor (VEGF) in the pathogenesis of neovascular age-related macular degeneration (nAMD) is well established. While anti-VEGF agents have transformed the management of nAMD, a substantial portion of patients exhibit suboptimal responses despite receiving optimal therapy, underscoring the need for new therapeutic targets. To address this gap, the present investigation aims to elicit novel associations between aqueous humor (AH) cytokines and clinical characteristics in patients with nAMD, with the goal of identifying new biomarkers for disease severity and potential therapeutic targets.Design: Cross-sectional analysis of a prospective clinical trial (NCT03056092). Methods: Treatment-naïve patients aged 50 years or older with active choroidal neovascularization secondary to nAMD were prospectively recruited between 2017 and 2023 at St. Michael’s Hospital in Toronto, Canada. Baseline AH samples (60-80 μL) were obtained via anterior chamber paracentesis from the inferotemporal quadrant prior to intravitreal ranibizumab injection. The MILLIPLEX® MAP Human Cytokine/Chemokine/Growth Factor Assay (Panel A) was used to quantify levels of platelet-derived growth factor (PDGF)-AA, monocyte chemoattractant protein (MCP)-1, interleukin (IL)-6, as well as C-X-C motif chemokine ligand (CXCL)-9 and CXCL-10. Correlations between AH cytokine levels and baseline clinical parameters such as best-corrected visual acuity (BCVA), central macular thickness (CMT), macular volume, and intraocular pressure (IOP) were analyzed using Stata v17.0 (College Station, Texas, USA). Results: A total of 24 eyes from 23 treatment-naïve patients with nAMD underwent AH analysis. The cohort included 17 (70.8%) females and 7 (29.2%) males, with a mean age of 79.0 ± 8.2 years. Baseline measurements showed a mean BCVA of 0.75 ± 0.63 logMAR (~20/125 Snellen), a mean macular volume of 10.48 ± 0.94 mm3, a mean CMT of 335.48 ± 75.99 μm, and a mean IOP was 14.00 ± 1.64 mmHg. The following cytokines were significantly associated with macular volume: PDGF-AA (r=0.70, p<0.001), MCP-1 (r=0.68, p<0.001), IL-6 (r=0.54, p=0.01), and IP-10 (r=0.53, p=0.04). Notably, PDGF-AA (r=0.65, p<0.01) and MCP-1 (r=0.57, p<0.01) levels were also significantly associated with CMT, whereas IP-10 (r=0.51, p=0.04) and MIG/CXCL9 (r=0.51, p=0.01) levels were significantly associated with IOP. Conclusions: Elevated AH concentrations of PDGF-AA, MCP-1, IL-6, and IP-10 may be associated with poorer anatomical outcomes in patients with nAMD. As cytokine changes can precede anatomical alterations detected on optical coherence tomography, these cytokines have the potential to serve as clinically valuable biomarkers for nAMD severity, as well as potential therapeutic targets for suppression. Future longitudinal research is warranted in this setting.