Trastuzumab does not bind rat or mouse ErbB2/neu: implications for selection of non-clinical safety models for trastuzumab-based therapeutics

• Published in: Breast cancer research and treatment Vol. 191; no. 2; pp. 303 - 317
• Main Authors: Lewis Phillips, Gail, Guo, Jun, Kiefer, James R., Proctor, William, Bumbaca Yadav, Daniela, Dybdal, Noel, Shen, Ben-Quan
• Format: Journal Article
• Language: English
• Published: New York Springer US 01-01-2022; Springer; Springer Nature B.V
• Subjects: Amino acid substitution; Amino acids; Animal models; Animals; Antibodies; Antibodies, Monoclonal, Humanized; Antigens; Biological products; Breast cancer; Breast Neoplasms; Cancer research; Cell lines; Cell viability; Chromatography, Liquid; Enzyme-linked immunosorbent assay; ErbB-2 protein; Ethylenediaminetetraacetic acid; Female; Flow cytometry; Hepatocytes; Homeopathy; Humans; Kinases; Materia medica and therapeutics; Maytansine - adverse effects; Medical research; Medicine; Medicine & Public Health; Mice; Monoclonal antibodies; Oncology; Pertuzumab; Pharmacokinetics; Preclinical Study; Rats; Reagents; Receptor, ErbB-2 - genetics; Safety; Safety and security measures; Tandem Mass Spectrometry; Targeted cancer therapy; Therapeutics; Toxicity; Trastuzumab; Trastuzumab - adverse effects; Binding; Human; T-DM1; Trastuzumab emtansine; Rodent; Trastuzumab
• ISSN: 0167-6806; 1573-7217
• DOI: 10.1007/s10549-021-06427-w

Purpose
Assessment of non-clinical safety signals relies on understanding species selectivity of antibodies. This is particularly important with antibody–drug conjugates, where it is key to determine target-dependent versus target-independent toxicity. Although it appears to be widely accepted that trastuzumab does not bind mouse or rat HER2/ErbB2/neu, numerous investigators continue to use mouse models to investigate safety signals of trastuzumab and trastuzumab emtansine (T-DM1). We, therefore, conducted a broad array of both binding and biologic studies to demonstrate selectivity of trastuzumab for human HER2 versus mouse/rat neu.
Methods
Binding of anti-neu and anti-HER2 antibodies was assessed by ELISA, FACS, IHC, Scatchard, and immunoblot methods in human, rat, and mouse cell lines. In human hepatocytes, T-DM1 uptake and catabolism were measured by LC-MS/MS; cell viability changes were determined using CellTiter-Glo.
Results
Our data demonstrate, using different binding methods, lack of trastuzumab binding to rat or mouse neu. Structural studies show important amino acid differences in the trastuzumab-HER2 binding interface between mouse/rat and human HER2 ECD. Substitution of these rodent amino acid residues into human HER2 abolish binding of trastuzumab. Cell viability changes, uptake, and catabolism of T-DM1 versus a DM1 non-targeted control ADC were comparable, indicating target-independent effects of the DM1-containing ADCs. Moreover, trastuzumab binding to human or mouse hepatocytes was not detected.
Conclusions
These data, in total, demonstrate that trastuzumab, and by extension T-DM1, do not bind rat or mouse neu, underscoring the importance of species selection for safety studies investigating trastuzumab or trastuzumab-based therapeutics.