gallium Ga 68-labeled tilmanocept

A radioconjugate composed of tilmanocept, a macromolecule consisting of multiple units of mannose and the chelating agent diethylenetriaminepentaacetic acid (DTPA) each covalently attached to a 10 kDa dextran backbone, labeled with the radioisotope gallium Ga 68, with potential use as a tracer for cancer sentinel lymph node (SLN) upon positron emission tomography (PET)/computed tomography (CT). Upon administration, the mannose moiety of gallium Ga 68-labeled tilmanocept selectively binds to macrophage mannose receptor 1 (mannose receptor; MR; CD206) expressed on the surface of macrophages and dendritic cells (DCs) in lymphatic tissue. Upon PET/CT imaging, SLN may be imaged and mapped. Tilmanocept exhibits rapid clearance from the injection site, rapid uptake and high retention within the first draining lymph node, and low uptake by the remaining lymph nodes. CD206, a member of the C-type lectin (CLEC) family that binds mannose or fucose carbohydrate residues, such as those found on the surfaces of many pathogens, is expressed on the surface of macrophages and DCs in lymphatic tissue.