Humanized dual-targeting antibody–drug conjugates specific to MET and RON receptors as a pharmaceutical strategy for the treatment of cancers exhibiting phenotypic heterogeneity

Cancer heterogeneity, characterized by diverse populations of tumorigenic cells, involves the occurrence of differential phenotypes with variable expressions of receptor tyrosine kinases. Aberrant expressions of mesenchymal-epithelial transition (MET) and recepteur d'origine nantais (RON) receptors contribute to the phenotypic heterogeneity of cancer cells, which poses a major therapeutic challenge. This study aims to develop a dual-targeting antibody-drug conjugate (ADC) that can act against both MET and RON for treating cancers with high phenotypic heterogeneity. Through immunohistochemical staining, we show that MET and RON expressions are highly heterogeneous with differential combinations in more than 40% of pancreatic and triple-negative breast cancer cases. This expressional heterogeneity provides the rationale to target both receptors for cancer therapy. A humanized bispecific monoclonal antibody specific to both MET and RON (PCMbs-MR) is generated through IgG recombination using monoclonal antibody sequences specific to MET and RON, respectively. Monomethyl auristatin E is conjugated to PCMbs-MR to generate a dual-targeting ADC (PCMdt-MMAE), with a drug-to-antibody ratio of 4:1. Various cancer cell lines were used to determine PCMdt-MMAE-mediated biological activities. The efficacy of PCMdt-MMAE in vivo is evaluated using multiple xenograft tumor models. PCMdt-MMAE shows a favorable pharmacokinetic profile, with a maximum tolerated dose of ~30 mg/kg in mice. Toxicological studies using Sprague-Dawley rats reveal that PCMdt-MMAE is relatively safe with slight-to-moderate, temporary, and reversible adverse events. Functionally, PCMdt-MMAE induces a robust internalization of both MET and RON and causes a large-scale cell death in cancer cell lines exhibiting MET and RON heterogeneous co-expressions. Both in vitro and in vivo studies demonstrate that the dual-targeting approach in the form of an ADC is highly effective with a long-lasting effect against tumors exhibiting MET/RON heterogeneous phenotypes. Hence, we can suggest that a dual-targeting ADC specific to both MET and RON can be employed as a novel therapeutic strategy for tumors with expressional phenotypic heterogeneity.