Antibody-Drug Conjugates Targeting the EGFR Ligand Epiregulin Elicit Robust Anti-Tumor Activity in Colorectal Cancer

Abstract

PurposeThe EGFR ligand, epiregulin (EREG), is highly expressed in colorectal cancers (CRCs) and a biomarker for predicting benefit inRASwildtype patients receiving EGFR-targeted therapies. Here, we report the development and preclinical evaluation of EREG-targeted antibody-drug conjugates (ADCs) incorporating diverse chemical linkers and duocarmycin DM (DuoDM) payload in CRC models of different mutational status and subtypes.Experimental DesignRNA-seq datasets from different patient cohorts were analyzed for EREG expression. EREG monoclonal antibody, H231, was characterized for specificity, affinity, internalization, and biodistribution and tumor uptake using89Zr-immunoPET. H231 was conjugated to a series of cleavable dipeptide and tripeptide linker-DuoDM payloads and cytotoxicity of EREG ADCs were assessed in a panel of CRC cell lines. Safety, antitumor efficacy, and survival was evaluated in vivo.ResultsEREG was high in bothRASmutant and wildtype tumors and inversely associated with microsatellite instability.89Zr-immunoPET showed significant tumor uptake of H231 with minimal uptake in normal tissues. EREG ADCs incorporating tripeptide linkers demonstrated highest potency in EREG-expressing CRC cells (IC50s = 0.01-0.50 nmol/L). EREG ADCs were safe and well-tolerated at doses tested and showed significant tumor growth inhibition with increased survival in patient-derived tumor xenograft models.ConclusionsEREG is a promising target for the development of ADCs for treating colorectal and other tumor types that express high levels of EREG. Importantly, EREG ADCs demonstrated significant therapeutic efficacy in bothRASmutant and wildtype CRC cell lines and tumors, suggesting their potential as an alternative to EGFR-targeted therapy to benefit a broader patient population.Translational RelevanceAs colorectal cancer (CRC) remains a leading cause of cancer-related death, identifying novel therapeutic targets and approaches is essential to improve patient outcomes. The epidermal growth factor receptor (EGFR) ligand epiregulin (EREG) is highly expressed on the surface ofRASwildtype and mutant colorectal tumors with minimal expression in normal tissues, making it a favorable target for antibody-drug conjugate (ADC) development. In this work, we generated novel EREG ADCs that show high selectivity and potency in CRC cells irrespective ofRASmutational status. Importantly, EREG ADCs were well-tolerated, caused significant tumor growth inhibition, and increased survival in patient-derived xenograft models. While efficacy of standard of care anti-EGFR therapies, cetuximab and panitumumab, are largely limited byRASmutation status, EREG ADCs may show promise for bothRASmutant and wildtype patients, thus improving existing treatment options.