Determining the Ocular Biocompatibility of a Novel VEGF-A and Ang-2 Bispecific Protein (RO-634) Through Histological Analysis

Abstract

Purpose : Antibodies against Vascular Endothelial Growth Factor-A (VEGF-A) and Angiopoietin-2 (Ang-2) are validated targets in the treatment of retinal disease. With the introduction of a novel bispecific protein, RO-634, dual targeting of VEGF-A and Ang-2 is possible. This study investigates the ocular biocompatibility of the bispecific, RO-634, using histological analysis.

Methods : All experiments were performed in accordance with the ARVO statement for Use of Animals in Ophthalmic and Vision Research. Five Brown Norway rats received intravitreal injections of RO-634 in the right eye, and BSS in the left eye to evaluate for potential retinal toxicity. One month post intravitreal injection, the rats were sacrificed, and retinal tissue was collected for histological analysis. The tissues were sectioned, stained, and analyzed via Imagepro software to quantify the number of cells present in ganglion, inner nuclear, and outer nuclear cell layers. Each layer was identified by the software in three distinct areas to increase accuracy in quantification. Following automated check, a manual count was conducted to ensure all cells were counted. Those samples that did not have adequate sectioning and fixation were discarded.

Results : RO-634 was well tolerated in the Brown Norway rats. Histological analysis between RO-634 and BSS did not demonstrate a statistically significant difference in cell count between ganglion cell layer (L=17.90 ± 1.31, R = 16.33 ± 1.11, T test = 0.40), outer nuclear cell layer (L= 156.04 ± 2.49, R = 153.09 ± 3.19, T test = 0.42) or inner nuclear cell layers (L=56.33 ± 2.11, R = 56.38 ± 1.42, T test = 0.98) within the retina (Figure 1), suggesting biocompatibility of RO-634.

Conclusions : The novel VEGF-A and Ang-2 bispecific protein (RO-634) demonstrates biocompatibility in this animal model. Further studies are needed to understand the therapeutic potential of this bispecific protein in retinal disease.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.

 

Figure 1: Comparison of nuclei cell counts of ganglion (GCL), inner-nuclear (INL), and outer-nuclear cell layers (ONL) between VEGF-A and Ang-2 bispecific (RO-634) and control (BSS) intravitreal injections.