Efficacy of Anti-RON Antibody Zt/g4–Drug Maytansinoid Conjugation (Anti-RON ADC) as a Novel Therapeutics for Targeted Colorectal Cancer Therapy

Abstract

Purpose: The receptor tyrosine kinase RON is critical in epithelial tumorigenesis and a drug target for cancer therapy. Here, we report the development and therapeutic efficacy of a novel anti-RON antibody Zt/g4-maytansinoid (DM1) conjugates for targeted colorectal cancer (CRC) therapy.Experimental Design: Zt/g4 (IgG1a/k) was conjugated to DM1 via thioether linkage to form Zt/g4-DM1 with a drug-antibody ratio of 4:1. CRC cell lines expressing different levels of RON were tested in vitro to determine Zt/g4-DM1-induced RON endocytosis, cell-cycle arrest, and cytotoxicity. Efficacy of Zt/g4-DM1 in vivo was evaluated in mouse xenograft CRC tumor model.Results: Zt/g4-DM1 rapidly induced RON endocytosis, arrested cell cycle at G 2 -M phase, reduced cell viability, and caused massive cell death within 72 hours. In mouse xenograft CRC models, Zt/g4-DM1 at a single dose of 20 mg/kg body weight effectively delayed CRC cell-mediated tumor growth up to 20 days. In a multiple dose-ranging study with a five injection regimen, Zt/g4-DM1 inhibited more than 90% tumor growth at doses of 7, 10, and 15 mg/kg body weight. The minimal dose achieving 50% of tumor inhibition was approximately 5.0 mg/kg. The prepared Zt/g4-DM1 is stable at 37 C for up to 30 days. At 60 mg/kg, Zt/g4-DM1 had a moderate toxicity in vivo with an average of 12% reduction in mouse body weight. Conclusion: Zt/g4-DM1 is highly effective in targeted inhibition of CRC cell-derived tumor growth in mouse xenograft models. This work provides the basis for development of humanized Zt/g4-DM1 for RON-targeted CRC therapy in the future. Clin Cancer Res; 20(23); 6045-58. Ó2014 AACR.

Preclinical studies of a Pro-antibody-drug conjugate designed to selectively target EGFR-overexpressing tumors with improved therapeutic efficacy

“…In addition, a preliminary toxicity study was performed in BALB/c mice and tumor-bearing nude mice by comparing the changes on body weight with injection of PanP-DM1. [26][27][28] To conclude, these data suggest that PanP-DM1, the first cancer-selective PDC for EGFR-targeted therapy, holds promise for clinical development because of its high potency and improved cancer selectivity.…”

“…injection of PanP-DM1 at 0, 25, 50, 75 or 100 mg/kg body weight. 26 In addition, toxicity associated with therapeutic dose was evaluated in nude mice bearing A431 and NCI-H292 cells (10 mice per group). Mice were observed for~15-20 d Toxicity was evaluated by observing mouse body weight loss.…”

RON Receptor Tyrosine Kinase as a Therapeutic Target for Eradication of Triple-Negative Breast Cancer: Efficacy of Anti-RON ADC Zt/g4-MMAE

“…Briefly, MC-VC-PAB-MMAE was coupled to cysteine residues of Zt/g4 after partial reduction of the interchain disulfide bonds to form Zt/g4-MMAE with an average DAR of 3.29:1. Zt/g4 conjugated with maytansinoid (Zt/g4-DM1) was used as previously described (26). Isotype-matched mouse IgG was conjugated with MC-VC-PAB-MMAE (CmIgG-MMAE) as the control.…”

“…Preliminary results indicate that suppressing RON signaling or targeting RON for drug delivery has the therapeutic potential for breast cancer treatment (18). Recently, a novel anti-RON antibody-drug conjugates (ADC) with significantly improved therapeutic index has been developed and used in preclinical studies (21,25,26), which open a new avenue for RON-targeted targeted therapy of breast cancer.…”

Monoclonal antibody Zt/g4 targeting RON receptor tyrosine kinase enhances chemosensitivity of bladder cancer cells to Epirubicin by promoting G1/S arrest and apoptosis

“…It was documented recently that Zt/g4 intracellular delivery of maytansinoid could result in cell cycle changes, suggesting that cell cycle arrest might contribute to enhancement of chemosensitivity by Zt/g4 (37). Therefore, we analyzed the cell cycle distribution of EPI-treated 5637 cells.…”