Engineering multivalent antibodies to target heregulin-induced HER3 signaling in breast cancer cells

Abstract

The use of antibodies in therapy and diagnosis has undergone an unprecedented expansion during the past two decades. This is due in part to innovations in antibody engineering that now offer opportunities for the production of “second generation” antibodies with multiple specificities or altered valencies. The targeting of individual components of the human epidermal growth factor receptor (HER)3-PI3K signaling axis, including the preferred heterodimerization partner HER2, is known to have limited anti-tumor effects. The efficacy of antibodies or small molecule tyrosine kinase inhibitors (TKIs) in targeting this axis is further reduced by the presence of the HER3 ligand, heregulin. To address these shortcomings, we performed a comparative analysis of two distinct approaches toward reducing the proliferation and signaling in HER2 overexpressing tumor cells in the presence of heregulin. These strategies both involve the use of engineered antibodies in combination with the epidermal growth factor receptor (EGFR)/HER2 specific TKI, lapatinib. In the first approach, we generated a bispecific anti-HER2/HER3 antibody that, in the presence of lapatinib, is designed to sequester HER3 into inactive HER2-HER3 dimers that restrain HER3 interactions with other possible dimerization partners. The second approach involves the use of a tetravalent anti-HER3 antibody with the goal of inducing efficient HER3 internalization and degradation. In combination with lapatinib, we demonstrate that although the multivalent HER3 antibody is more effective than its bivalent counterpart in reducing heregulin-mediated signaling and growth, the bispecific HER2/HER3 antibody has increased inhibitory activity. Collectively, these observations provide support for the therapeutic use of bispecifics in combination with TKIs to recruit HER3 into complexes that are functionally inert.

Macrophage-Mediated Trogocytosis Leads to Death of Antibody-Opsonized Tumor Cells

“…Trastuzumab, rituximab, pertuzumab and pertuzumab Fab fragments were labeled using Alexa 488 or 555 labeling kits (Life Technologies). The construction of trastuzumab heavy and light chain expression constructs was performed as described previously (24). Mutations to enhance the binding of trastuzumab (human IgG1) to FcγRs, G236A/I332E (AE) and G236A/S239D/I332E (ADE; 13) were introduced into the trastuzumab expression construct by splicing by overlap extension (25).…”

Heregulin/ErbB3 Signaling Enhances CXCR4-Driven Rac1 Activation and Breast Cancer Cell Motility via Hypoxia-Inducible Factor 1α

“…Enhanced HRG/ErbB3 signaling has also been implicated in resistance to anticancer agents, including antiestrogens, ErbB tyrosine kinase inhibitors, and taxanes, and adaptive responses leading to drug resistance involve reprogramming of the kinome through reactivation of an HRG/ErbB3 axis (23)(24)(25)(26)(27)(28)(29). Consistent with the critical role of ErbB3 activation in breast cancer and other cancers, several targeted approaches designed to block HRG/ErbB3 are currently under clinical evaluation (30)(31)(32). Despite the recognized complexities of ErbB4 signaling and controversies regarding its role in cancers, this HRG receptor has been also implicated in breast tumorigenesis (33,34).…”

Emerging anti-cancer antibodies and combination therapies targeting HER3/ERBB3

“…So far, Tab6 was used in vitro, either alone or in combination with lapatinib, and showed an ability to decrease proliferation of breast cancer cells overexpressing HER2. 168 Sym013 (Pan-HER) is a mixture of 6 mAbs, comprising 3 pairs of synergistic mAbs, each targeting EGFR, HER2 and HER3. 169 The mixture has been reported to effectively inhibit growth of lung (NSCLC) and head and neck (HNSCC) cancer models in vitro and in vivo.…”