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Published on: June 13, 2014
Novel Humanized Anti-HER3 Antibodies: Structural Characterization and Therapeutic Activity
Alessia Muzi1, Roberto Arriga1, Giovanni Bulfaro2
1Takis s.r.l., 00128 Rome, Italy.
Background/Objectives:
The ErbB protein family plays a critical role in the progression of various solid tumors, and HER3 has been implicated in resistance mechanisms to multiple cancer therapies due to its ability to form heterodimers with other ErbB receptors, thereby activating pathways that promote tumor growth and survival. This study aimed to generate and characterize humanized monoclonal antibodies against HER3 to inhibit its function and evaluate their potential as therapeutic agents.
Methods:
Murine monoclonal antibodies TK-A3 and TK-A4 were humanized and tested for binding to ErbB3 and competition with neuregulin-1β (NRG). Specificity was assessed by ELISA, and epitope identified by X-ray crystallography. Downstream signaling was analyzed by western blot for phosphorylated ErbB3, Akt, and MAPK. Antitumor activity was evaluated in vitro and in a pancreatic cancer xenograft model. A toxicology study was also conducted.
Results:
TK-hu A3 and TK-hu A4 bound specifically to ErbB3 without cross-reactivity to other ErbB receptors. The ErbB3-TK-hu A3 Fab structure revealed the binding epitope. Both antibodies competed with NRG, inhibiting ErbB3, Akt, and MAPK phosphorylation in a dose-dependent manner. They suppressed cancer cell survival in vitro, and TK-hu A3 significantly delayed tumor growth in vivo. The toxicology study indicated good tolerability.
Conclusions:
TK-hu A3 emerged as the lead candidate, showing specific HER3 targeting, strong pathway inhibition, and antitumor efficacy in vivo. Beyond standalone use, it could support novel strategies such as T-cell engagers, ADCs, CAR-T, and bispecific antibodies. These findings highlight TK-hu A3 as a promising therapy for HER3-positive, treatment-resistant cancers, meriting further development.
Insights
Humanized antibodies targeting HER3 (Human Epidermal growth factor Receptor 3) were developed. TK-hu A3 effectively inhibited HER3 signaling and demonstrated significant antitumor activity in preclinical models.
Area of Science:
- Oncology
- Immunology
- Molecular Biology
Background:
- The ErbB protein family, including HER3, is crucial in solid tumor progression.
- HER3 activation promotes tumor growth and survival, contributing to therapy resistance.
- HER3's role in heterodimerization with other ErbB receptors drives oncogenic signaling.
Purpose of the Study:
- To generate and characterize humanized monoclonal antibodies targeting HER3.
- To evaluate the therapeutic potential of these antibodies in inhibiting HER3 function.
- To assess the antibodies' efficacy against HER3-driven cancers.
Main Methods:
- Humanization of murine monoclonal antibodies TK-A3 and TK-A4.
- Assessment of antibody binding to HER3 and competition with neuregulin-1β (NRG).
- Analysis of downstream signaling pathways (p-ErbB3, Akt, MAPK) and in vitro/in vivo antitumor activity.
Main Results:
- TK-hu A3 and TK-hu A4 demonstrated specific binding to HER3 without cross-reactivity.
- Antibodies competed with NRG, inhibiting key signaling pathways in a dose-dependent manner.
- TK-hu A3 showed significant in vitro and in vivo antitumor efficacy with good tolerability.
Conclusions:
- TK-hu A3 is a promising lead candidate for HER3-targeted therapy.
- The antibody exhibits specific HER3 targeting, potent pathway inhibition, and antitumor activity.
- TK-hu A3 holds potential for combination therapies and treating resistant HER3-positive cancers.
