Replies to post #312631 on Avid Bioservices Inc (CDMO)

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STILL OUR IP? chinese to me ...

>>we have generated PS-targeting agents by fusing PS-binding domains to a human IgG1-derived Fc fragment. The tumor localization and pharmacokinetics of several PS-specific Fc fusions have been analyzed in mice and demonstrate that Fc-Syt1, a fusion containing the synaptotagmin 1 C2A domain, effectively targets tumor tissue. Conjugation of Fc-Syt1 to the cytotoxic drug, monomethyl auristatin E, results in a protein-drug conjugate (PDC) that is internalized into target cells and, due to the Ca²?-dependence of PS binding, dissociates from PS in early endosomes. The released PDC is efficiently delivered to lysosomes and has potent anti-tumor effects in mouse xenograft tumor models. Interestingly, whilst an engineered, tetravalent Fc-Syt1 fusion shows increased binding to target cells, this higher avidity variant demonstrates reduced persistence and therapeutic effects compared with bivalent Fc-Syt1. Collectively, these studies show that finely tuned, Ca²?-switched PS-targeting agents can be therapeutically efficacious.