Development and biological assessment of MMAE-trastuzumab antibody–drug conjugates (ADCs)

Trastuzumab, a humanized monoclonal antibody targeting Human Epidermal growth factor Receptor 2 (HER2), is a therapeutic option used for the treatment of patients with HER2-overexpressing breast cancers. The primary purpose of the present study was to establish a trastuzumab-based antibody drug conjugate (ADC) to enhance the biopharmaceutical profile of trastuzumab. In this study, trastuzumab was linked to the microtubule-disrupting agent monomethyl auristatin E (MMAE) through a peptide linker. Following conjugation, MMAE-trastuzumab ADCs were characterized using SDS-PAGE, UV/VIS, and cell-based ELISA. The inhibitory effects of the ADCs were measured on MDA-MB-453 (HER2-positive cells) and HEK-293 (HER2-negative cells) using in vitro cell cytotoxicity and colony formation assays. Our findings showed that approximately 3.4 MMAE payloads were conjugated to trastuzumab. MMAE-trastuzumab ADCs produced six bands, including H2L2, H2L, HL, H2, H, and L in non-reducing SDS-PAGE. The conjugates exhibited the same binding ability to MDA-MB-453 as unconjugated trastuzumab. The MTT assay showed a significant improvement in the trastuzumab activity following MMAE conjugation, representing a higher antitumor activity as compared with unconjugated trastuzumab. Furthermore, ADCs were capable of potentially inhibiting colony formation in HER2-positive cells, as compared with trastuzumab. MMAE-trastuzumab ADCs represent a promising therapeutic strategy to treat HER2-positive breast cancer.