ABSTRACT
The cell surface glycoprotein P-cadherin is highly expressed in a number of malignancies, including those arising in the epithelium of the bladder, breast, esophagus, lung, and upper aerodigestive system. PCA062 is a P-cadherin specific antibody-drug conjugate that utilizes the clinically validated SMCC-DM1 linker payload to mediate potent cytotoxicity in cell lines expressing high levels of P-cadherin in vitro, while displaying no specific activity in P-cadherin-negative cell lines. High cell surface P-cadherin is necessary, but not sufficient, to mediate PCA062 cytotoxicity. In vivo, PCA062 demonstrated high serum stability and a potent ability to induce mitotic arrest. In addition, PCA062 was efficacious in clinically relevant models of P-cadherin-expressing cancers, including breast, esophageal, and head and neck. Preclinical non-human primate toxicology studies demonstrated a favorable safety profile that supports clinical development. Genome-wide CRISPR screens reveal that expression of the multidrug-resistant gene ABCC1 and the lysosomal transporter SLC46A3 differentially impact tumor cell sensitivity to PCA062. The preclinical data presented here suggest that PCA062 may have clinical value for treating patients with multiple cancer types including basal-like breast cancer.
Subject(s)
Antineoplastic Agents, Immunological/pharmacology , Biomarkers, Tumor , Cadherins/genetics , Immunoconjugates/pharmacology , Neoplasms/genetics , Amino Acid Sequence , Animals , Antibody-Dependent Cell Cytotoxicity/immunology , Antineoplastic Agents, Immunological/chemistry , Antineoplastic Agents, Immunological/pharmacokinetics , Binding Sites , Cadherins/chemistry , Cadherins/metabolism , Cell Line, Tumor , Disease Models, Animal , Drug Resistance, Neoplasm , Gene Expression , Humans , Immunoconjugates/chemistry , Immunoconjugates/pharmacokinetics , Immunohistochemistry , Macaca fascicularis , Mice , Models, Molecular , Neoplasms/drug therapy , Neoplasms/metabolism , Neoplasms/pathology , Protein Binding , Protein Transport , Rats , Structure-Activity Relationship , Xenograft Model Antitumor AssaysABSTRACT
Numerous lines of evidence suggest that the polypeptide hormone prolactin (PRL) may contribute to breast and prostate tumorigenesis through its interactions with the prolactin receptor (PRLR). Here, we describe the biologic properties of LFA102, a humanized neutralizing monoclonal antibody directed against the extracellular domain of PRLR. This antibody was found to effectively antagonize PRL-induced signaling in breast cancer cells in vitro and in vivo and to block PRL-induced proliferation in numerous cell line models, including examples of autocrine/paracrine PRL activity. A single administration of LFA102 resulted in regression of PRL-dependent Nb2-11 tumor xenografts and significantly prolonged time to progression. Finally, LFA102 treatment significantly inhibited PRLR signaling as well as tumor growth in a carcinogen-induced, estrogen receptor-positive rat mammary cancer model as a monotherapy and enhanced the efficacy of the aromatase inhibitor letrozole when administered in combination. The biologic properties of LFA102, elucidated by the preclinical studies presented here, suggest that this antibody has the potential to be a first-in-class, effective therapeutic for the treatment of PRL-dependent cancers.
