Site-specific conjugation of auristatins onto engineered antibody fragments to target her2-positive breast cancer in vitro

poster + "pitch" de présentation du poster de 90sposter + "pitch" de présentation du poster de 90sThe combination of a highly potent cytotoxic agent (drug) with a specific therapeutic monoclonal antibody (mAb) via a suitably constructed spacer arm (linker) (Figure 1) appear to be an ideal embodiment of the “magic bullet” concept leading to the development of a novel therapeutic class named Antibody-Drug-Conjugates (ADC). This armed antibodies can be viewed as a way to improve tumor-cell killing while sparing normal tissues. While ADC have been successfully implemented in clinical strategies for the treatment of hematological cancers, the case of solid tumors suffer from insufficient ADCs activity at the maximum doses that can be tolerated. Currently, almost all ADC in clinical trials are based on canonical IgG molecules associated with limitations including bad tumor penetration as well as Fc-mediated off-target toxicity, due to an increase of normal tissue exposure (due to long half-life via FcRn recycling) and cross reaction with immune cells (due to Fc R interactions). Thereby, the aim of our project is to use antibody fragments to try to circumvent this limitations.Our strategy is based on a site-specific conjugation of an auristatin derivative onto an engineered anti-HER2 antibody fragment including single chain fragment variable (scFv) of the trastuzumab antibody, generating new scFv-drug conjugates (SDC). Cysteines were judiciously incorporated in the scFv aminoacid sequence to allow controlled bioconjugation of a heterobifunctional linker, either cleavable (for monomethyl auristatin E) or noncleavable (for monomethyl auristatin F) (Figure 1)