A bi-functional antibody-receptor domain fusion protein simultaneously targeting IGF-IR and VEGF for degradation

Abstract

Bi-specific antibodies (BsAbs), which can simultaneously block 2 tumor targets, have emerged as promising therapeutic alternatives to combinations of individual monoclonal antibodies. Here, we describe the engineering and development of a novel, human bi-functional antibody-receptor domain fusion molecule with ligand capture (bi-AbCap) through the fusion of the domain 2 of human vascular endothelial growth factor receptor 1 (VEGFR1) to an antibody directed against insulin-like growth factor – type I receptor (IGF-IR). The bi-AbCap possesses excellent stability and developability, and is the result of minimal engineering. Beyond potent neutralizing activities against IGF-IR and VEGF, the bi-AbCap is capable of cross-linking VEGF to IGF-IR, leading to co-internalization and degradation of both targets by tumor cells. In multiple mouse xenograft tumor models, the bi-AbCap improves anti-tumor activity over individual monotherapies. More importantly, it exhibits superior inhibition of tumor growth, compared with the combination of anti-IGF-IR and anti-VEGF therapies, via powerful blockade of both direct tumor cell growth and tumor angiogenesis. The unique “capture-for-degradation” mechanism of the bi-AbCap is informative for the design of next-generation bi-functional anti-cancer therapies directed against independent signaling pathways. The bi-AbCap design represents an alternative approach to the creation of dual-targeting antibody fusion molecules by taking advantage of natural receptor-ligand interactions.

Aberrant bispecific antibody pharmacokinetics linked to liver sinusoidal endothelium clearance mechanism in cynomolgus monkeys

“…2A-C and 3). As the fusion partner to mAbs G1, G2 and G3 for the BsAb model system, we used the well-folded »11.5 kDa D2 domain of VEGFR1 described previously 19 as the ECD fusion partner to the 3 different IgGs with the same fusion position orientation and linker region. The ECD binds its soluble targets VEGF-A and PlGF, which are known to have low ng/mL and pg/mL circulating concentrations in the blood of normal animals, respectively.…”

“…1). The IgG-ECD construct used the D2 domain of vascular endothelial growth factor receptor 1 (VEGFR1, reported previously 19 ), an »11.5 kDa protein, as the ECD fusion partner to 3 different IgGs with similar orientation and linker (yielding G1-ECD, G2-ECD, G3-ECD). The IgGscFv construct was made with a scFv that was targeted to a soluble ligand having minimal peripheral concentrations in normal animals.…”

Significance of Selective Protein Degradation in the Development of Novel Targeted Drugs and Its Implications in Cancer Therapy

“…[ 86 ] Another BsAb, named bi‐AbCap, was reported to target insulin‐like growth factor I receptor and vascular endothelial growth factor for degradation through a lysosome‐dependent pathway. [ 87 ] Moreover, the tetravalent anti‐HER3 antibody Ab6tet, which is synthesized by the binding of two bivalent components through a Gly‐Ser‐Ser linker, promotes HER3 degradation in breast cancer cells. [ 88 ]…”

Emerging Strategies for Developing Next-Generation Protein Therapeutics for Cancer Treatment

“…Sweeping antibodies have been shown to reduce antigen concentration 50–1000 fold compared to conventional antibodies [107]. A similar format of antigen-clearing antibodies has been developed that uses IGF-IR as a membrane anchor instead of FcRn [108]. …”