The Half Maximal Effective Concentration (EC50) of a Novel VEGF-A and Ang-2 Bispecific Protein (RO-634) for Back of the Eye Disease

Abstract

Purpose : To investigate the half maximal effective concentration (EC50) of a novel bispecific protein, RO-634, to Vascular Endothelial Growth Factor-A (VEGF-A) and Angiopoietin-2 (Ang-2) individually versus in tandem. These findings may have important clinical implications for treatment of retinal disease including diabetic macular edema and exudative macular degeneration.

Methods : An Enzyme-linked Immunoassay (ELISA) was utilized to determine the EC50 of the bispecific RO-634 to recombinant human VEGF-A and human Ang-2 analytes independently and in combination. A polyclonal antibody was used to detect when RO-634 bound individually to VEGF-A or Ang-2, while Streptavidin Horseradish Peroxidase (SA-HRP) was used when RO-634 bound both analytes (Figure 1).

Results : The data demonstrate the bispecific RO-634 has an EC50 for solely VEGF-A of 10.04 pM and an EC50 for solely Ang-2 of 136 pM. The bispecific RO-634 demonstrated a lower EC50 to Ang-2 while bound jointly to VEGF-A of 101.9 pM (Figure 2).

Conclusions : Our data suggests EC50 for RO-634 to Ang-2 decreases when the bispecific is also bound to VEGF-A. This synergistic effect could be due to a conformational change that occurs when RO-634 is bound to VEGF-A. Further testing should be done to assess the pharmacokinetics behind the demonstrated synergistic effect.

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

 

The binding configuration for the bispecific RO-634 to VEGF-A and Ang-2 test in the ELISA described.

 

Comparison of RO-634 binding to the control vs VEGF and Ang-2 vs VEGF-A only vs Ang-2 only. EC50 in this graph is demonstrated using Log [RO-634] in nanomolars (nM).