A Site-Specifically Modified Imaging-Enabled Antibody-Drug Conjugate for Therapy and ImmunoPET

The conjugation of antibodies with cytotoxic drugs can alter their in vivo pharmacokinetics. As a result, the careful assessment of the in vivo behavior and specifically the tumor-targeting properties of antibody-drug conjugates represents a crucial step in their development. In order to facilitate this process, we have created a methodology that facilitates the dual labeling of an antibody with both a toxin and a radionuclide for positron emission tomography (PET). To minimize the impact of these modifications, this chemoenzymatic approach leverages strain-promoted azide-alkyne click chemistry to graft both cargoes to the heavy chain glycans of the immuoglobulin’s Fc domain. As a proof-of-concept, a HER2-targeting trastuzumab immunoconjugate was created bearing both a monomethyl auristatin E (MMAE) toxin as well as the long-lived positron-emitting radiometal 89Zr (t1/2 ~ 3.3 days). Both the tumor targeting and therapeutic efficacy of the 89Zr-trastuzumab-MMAE immunoconjugate were validated in vivo using ...