A bivalent, bispecific Dab-Fc antibody molecule for dual targeting of HER2 and HER3

Abstract

Dual targeting of surface receptors with bispecific antibodies is attracting increasing interest in cancer therapy. Here, we present a novel bivalent and bispecific antagonistic molecule (Dab-Fc) targeting human epidermal growth factors 2 and 3 (HER2 and HER3) derived from the Db-Ig platform, which was developed for the generation of multivalent and multispecific antibody molecules. Dab-Fc comprises the variable domains of the anti-HER2 antibody trastuzumab and the anti-HER3 antibody 3–43 assembled into a diabody-like structure stabilized by C H 1 and C L domains and further fused to a human γ1 Fc region. The resulting Dab-Fc 2 × 3 molecule retained unhindered binding to both antigens and was able to bind both antigens sequentially. In cellular experiments, the Dab-Fc 2 × 3 molecule strongly bound to different tumor cell lines expressing HER2 and HER3 and was efficiently internalized. This was associated with potent inhibition of the proliferation and migration of these tumor cell lines. Furthermore, IgG-like pharmacokinetics and anti-tumoral activity were demonstrated in a xenograft tumor model of the gastric cancer cell-line NCI-N87. These results illustrate the suitability of our versatile Db-Ig platform technology for the generation of bivalent bispecific molecules, which has been successfully used here for the dual targeting of HER2 and HER3.

Design and selection of optimal ErbB-targeting bispecific antibodies in pancreatic cancer

“…Thus the BiXAb™ format offers a versatile platform for the rapid generation of tetravalent bispecific antibodies. The tetravalent nature of the BiXAb™ format allowed maintaining the “bivalent avidity” towards the receptors observed for the parental mAbs, which is often not the case with some other BsAb formats composed of monovalent antigen binders ( 40 , 42 , 43 , 51 ). On the basis of the recently described dynamic model of antibody/antigen interaction ( 68 ), compared to BsAb formats with monovalent antigen binding, the BiXAb™ format, with bivalent antigen-binding sites, should more efficiently induce avidity-mediated interactions, such as antigen-antibody bivalent binding and complex formation (first-order avidity) and clustering of antigen-antibody complexes on the cancer cell surface (second-order avidity).…”

“…Our original pseudo-hinge format between Fab1 and Fab2 probably facilitates BiXAb™ structural constraints, and optimizes the distance/orientation of the four paratopes for efficient avidity interactions. Other factors, including IgG subclasses ( 84 ), internalization and degradation ( 51 , 58 , 84 , 88 ) also can affect the affinity/avidity equilibrium of BsAb interactions, and the subsequent therapeutic index. Moreover, the high affinity of tetravalent BiXAb™ (similar to that of mAbs), their potential ability to bind to FcRn via their functional Fc, and their larger size (compared to the parental mAbs) may lead to more favorable pharmacokinetic/pharmacodynamic profiles compared to those of mAbs or combinations.…”

“…The anti-EGFR/HER3 BsAb SI-B001 is included in phase 2/3 trials in lung cancer ( 41 ). Moreover, anti-EGFR/HER2 ( 48 , 49 ), anti-HER2/HER3 ( 50 , 51 ) and anti-EGFR/HER3 ( 52 , 53 ) BsAbs, and a tetravalent anti-EGFR/HER2/HER3/VEGF antibody ( 54 ) have been evaluated in pre-clinical studies.…”

HER3 in cancer: from the bench to the bedside

“…Indeed, this bAb in combination with trastuzumab is also effective in colorectal cancer models, bypassing NRG-induced resistance to anti-EGFR therapies [227]. The same lab had also generated Dab-Fc 2 × 3 molecule, an innovative bivalent and bispecific molecule (Dab-Fc) that targets HER2 and HER3 with anti-tumoral activity in vitro and in vivo [228]. Dab-Fc comprises the variable domains of trastuzumab (anti-HER2 Ab) and IgG 3-43 (anti-HER3 Ab) assembled into a diabody-like construction stabilized by CH1 and CL domains and fused to a human γ1 Fc region.…”

A scDb-based trivalent bispecific antibody for T-cell-mediated killing of HER3-expressing cancer cells

“…However, there is still no approved treatment targeting HER3 and clinical trials for the two most prominent candidates patritumab 9 and seribantumab 10 were terminated due to lack of efficacy (NCT02134015, NCT03241810). As extensive signaling crosstalk and redundancy was observed between the EGFR family members, combinatorial treatment strategies have been developed 11 , including antibody combinations and bispecific antibodies for dual targeting of HER3 and other members of the EGFR family 12 – 17 . However, also these approaches face several limitations.…”