Anti-Angiogenic Activity of a Tetravalent Bispecific Antibody (TAvi6) Targeting VEGF and Angiopoietin-2

VEGF blockade has been validated clinically as a treatment for human cancers. Angiopoietin-2 (Ang-2) expression has been shown to function as a key regulator of blood vessel remodeling and tumor angiogenesis. Several publications described that VEGF and Ang-2 are up-regulated in several hematological tumors like B-CLL, AML or multiple myeloma. In particular, Ang-2 may qualify as a novel prognostic marker in AML and CLL. We have generated TAvi6, a novel bispecific antibody targeting VEGF-A and Ang-2 and tested its anti-tumor and anti-angiogenic activity. TAvi6 is a tetravalent IgG-like bispecific antibody based on bevacizumab and targets Ang-2 with 2 disulfide-stabilized scFvs (LC06) fused to the C-terminus of the heavy chain.

TAvi 6 was profiled in biochemical and cellular (angiogenesis) assays. Antitumoral and anti-angiogenic efficacy was assessed in established s.c. Colo205, s.c. Calu-3 and orthotopic i.m.f.p. KPL-4 xenografts in SCID beige mice. Mice were treated with bevacizumab or <Ang-2> antibody LC06 (10 mg/kg), the respective combination (each 10 mg/kg) and TAvi6 (13.3 mg/kg). In addition, TAvi6 was evaluated for inhibition of metastasis to the lung quantified by Alu-PCR. Tumors were explanted for histological analysis of angiogenesis and inhibition of angiogenesis was assessed in the cornea angiogenesis assay.

In biochemical assays (affinity, Tie2-Ang-2 interaction) and cellular assays (Tie2 phosphorylation, HUVEC proliferation, tube formation) TAvi6 shows properties identical to the parental antibodies bevacizumab and LC06. In the orthotopic KPL-4-003 xenograft tumor growth inhibition was 79% for bevacizumab; 39% for LC06; 90% for the combination and 91% for TAvi6. In the s.c. Colo205-009 xenograft TGI was 66% for bevacizumab; 50% for LC06; 78% for the combination and 87% for TAvi6. TAvi6 was able to suppress growth of tumors refractory to 1^st-line treatment with bevacizumab (Colo205 xenograft) and suppressed metastasis to the lung significantly (KPL-4 xenograft). In the s.c. Calu-3 xenograft we observed a strong inhibition of angiogenesis by in vivo and ex vivo imaging and an advantage of TAvi6 compared to the antibody combination. Furthermore, TAvi6 potently inhibited VEGF-induced angiogenesis in the mouse corneal angiogenesis assay.

We have generated a novel tetravalent IgG-like bispecific antibody targeting VEGF-A and Ang-2 simultaneously. TAvi6 shows identical properties compared to the respective parental antibodies. In particular, TAvi6 blocks angiogenesis in vivo efficacously and mediates strong tumor growth inhibition in various xenograft models with a slight advantage of TAvi6 over the combination of the respective single agents bevacizumab and LC06 in several models. Further studies are foreseen to assess the application of bispecific antibodies targeting Ang-2 and VEGF as novel therapeutic approach for the treatment of hematological cancers.

Weidner:Roche: Employment, Equity Ownership. Scheuer:Roche: Employment, Patents & Royalties. Thomas:Roche: Employment, Patents & Royalties. Baehner:Roche: Employment, Patents & Royalties. Seeber:Roche: Employment, Patents & Royalties. Kettenberger:Roche: Employment, Patents & Royalties. Schanzer:Roche: Employment, Patents & Royalties. Brinkmann:Roche: Employment, Patents & Royalties. Regula:Roche: Employment, Patents & Royalties. Klein:Roche: Employment, Equity Ownership, Patents & Royalties.