Optimal Humanized Scg3-Neutralizing Antibodies for Anti-Angiogenic Therapy of Diabetic Retinopathy

Authors

Chengchi Huang
Prabuddha Waduge
Avinash Kaur
Hong Tian
Christina Y Weng
John Timothy Stout
Iok-Hou Pang
Keith A Webster
Wei Li

Publication Date

9-1-2024

Journal

International Journal of Molecular Sciences

DOI

10.3390/ijms25179507

PMID

39273454

PMCID

PMC11394726

PubMedCentral® Posted Date

9-1-2024

PubMedCentral® Full Text Version

Post-print

Published Open-Access

yes

Keywords

Diabetic Retinopathy, Humans, Animals, Mice, Human Umbilical Vein Endothelial Cells, Antibodies, Neutralizing, Angiogenesis Inhibitors, Cell Movement, Cell Proliferation, Antibodies, Monoclonal, Humanized, Mice, Inbred C57BL, RNA-Binding Proteins, Adaptor Proteins, Signal Transducing, secretogranin III, Scg3, anti-Scg3 therapy, Scg3-neutralizing antibodies, diabetic retinopathy, choroidal neovascularization

Abstract

Secretogranin III (Scg3) is a diabetic retinopathy (DR)-restricted angiogenic factor identified in preclinical studies as a target for DR therapy. Previously, our group generated and characterized ML49.3, an anti-Scg3 monoclonal antibody (mAb) which we then converted into an EBP2 humanized antibody Fab fragment (hFab) with potential for clinical application. We also generated anti-Scg3 mT4 mAb and related EBP3 hFab. In this study, to identify the preferred hFab for DR therapy, we compared all four antibodies for binding, neutralizing and therapeutic activities in vitro and in vivo. Octet binding kinetics analyses revealed that ML49.3 mAb, EBP2 hFab, mT4 mAb and EBP3 hFab have Scg3-binding affinities of 35, 8.7, 0.859 and 0.116 nM, respectively. Both anti-Scg3 EBP2 and EBP3 hFabs significantly inhibited Scg3-induced proliferation and migration of human umbilical vein endothelial cells in vitro, and alleviated DR vascular leakage and choroidal neovascularization with high efficacy. Paired assays in DR mice revealed that intravitreally injected EBP3 hFab is 26.4% and 10.3% more effective than EBP2 hFab and aflibercept, respectively, for ameliorating DR leakage. In conclusion, this study confirms the markedly improved binding affinities of hFabs compared to mAbs and further identifies EBP3 hFab as the preferred antibody to develop for anti-Scg3 therapy.