Proteomic profiles in the aqueous following anti-vegf therapy in treatment naïve neovascular age-related macular degeneration.

BACKGROUND/STUDY OBJECTIVES: Age-related macular degeneration (AMD), a degenerative disease of the photoreceptor support system of the macula, is a leading cause of vision loss in individuals over 60 years of age. In this exploratory longitudinal study, we studied VEGF-related proteins and other protein concentrations in the aqueous humor of patients with treatment naïve neovascular AMD (defined as patients with a previously untreated and recently diagnosed advanced neovascular form of AMD (NVAMD) who were eligible for an intra-vitreal administration of an anti-VEGF agent to treat choroidal neovascularization). The objectives of this small pilot study were: (1) To determine levels of VEGF-related proteins in the aqueous humor of treatment naïve NVAMD patients compared with control patients, (2) To determine whether levels of VEGF-related proteins change over time with anti-VEGF injections in NVAMD patients, (3) To put these differences into perspective relative to all protein targets and identify other off-target (non-VEGF) proteins that may be related to NVAMD or NVAMD treatment.

METHODS

We used an aptamer-based proteomic technology to study protein concentrations. Cases had a sample of aqueous collected immediately prior to starting the anti-VEGF intra-vitreal injection and at two follow-up visits. Controls were cataract patients with no AMD. Aqueous was collected at the time of cataract surgery.

RESULTS

Comparison between 9 cases and 11 controls revealed 56 proteins, out of 3,803 targets, with significant differences in baseline levels. After treatment, a decline in aqueous VEGF concentrations was indicated from two aptamer reagents, while a third recorded a significant increase. Interference studies demonstrated that the increase in levels observed for the latter reagent was due to measuring both drug-bound and free VEGF concentrations (total VEGF) while the others measured only free VEGF.

CONCLUSIONS

In this exploratory study, 56 proteins were identified that could potentially be linked with NVAMD. In interference studies free aqueous VEGF levels declined while total VEGF levels increased following anti-VEGF treatment. No large off-target effects on the proteome were observed with treatment. We illustrate how the protein interactome can mask or potentially unmask binding epitopes leading to signal changes not necessarily related to the absolute protein level.