Anti-tumor efficacy of an MMAE-conjugated antibody targeting cell surface TACE/ADAM17-cleaved Amphiregulin in breast cancer

Kristopher A Lofgren; Sreeja Sreekumar; E Charles Jenkins Jr; Kyle J Ernzen; Paraic A Kenny

doi:10.1093/abt/tbab026

Anti-tumor efficacy of an MMAE-conjugated antibody targeting cell surface TACE/ADAM17-cleaved Amphiregulin in breast cancer

Antib Ther. 2021 Nov 10;4(4):252-261. doi: 10.1093/abt/tbab026. eCollection 2021 Oct.

Authors

Kristopher A Lofgren¹, Sreeja Sreekumar¹, E Charles Jenkins Jr², Kyle J Ernzen¹, Paraic A Kenny^{1

3}

Affiliations

¹ Kabara Cancer Research Institute, Gundersen Medical Foundation, La Crosse, Wisconsin, USA.
² Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, New York, USA.
³ Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA.

Abstract

Background: The Epidermal Growth Factor Receptor (EGFR) ligand, Amphiregulin (AREG), is a key proliferative effector of estrogen receptor signaling in breast cancer and also plays a role in other malignancies. AREG is a single-pass transmembrane protein proteolytically processed by TACE/ADAM17 to release the soluble EGFR ligand, leaving a residual transmembrane stalk that is subsequently internalized.

Methods: Using phage display, we identified antibodies that selectively recognize the residual transmembrane stalk of cleaved AREG. Conjugation with fluorescence labels and monomethyl auristatin E (MMAE) was used to study their intracellular trafficking and anti-cancer effects, respectively.

Results: We report the development of an antibody-drug conjugate (ADC), GMF-1A3-MMAE, targeting an AREG neo-epitope revealed following ADAM17-mediated cleavage. The antibody does not interact with uncleaved AREG, providing a novel means of targeting cells with high rates of AREG shedding. Using fluorescent dye conjugation, we demonstrated that the antibody is internalized by cancer cells in a manner dependent on the presence of cell surface cleaved AREG. Antibodies conjugated with MMAE were cytotoxic in vitro and induced rapid regression of established breast tumor xenografts in immunocompromised mice. We further demonstrate that these antibodies recognize the AREG neo-epitope in formalin-fixed, paraffin-embedded tumor tissue, suggesting their utility as a companion diagnostic for patient selection.

Conclusions: This ADC targeting AREG has potential utility in the treatment of breast and other tumors in which proteolytic AREG shedding is a frequent event.

Keywords: ADC; amphiregulin; breast cancer; estrogen receptor; targeted delivery.