Definition

A radiotracer composed of a nanobody against the macrophage mannose receptor (MMR, CD206) conjugated with the bifunctional, macrocyclic chelating agent 1,4,7-triazacyclononane-N,N’,N”-triacetic acid (NOTA) and labeled with the radionuclide gallium Ga 68, with potential imaging activity using positron emission tomography (PET). Upon administration, the nanobody moiety of gallium Ga 68-NOTA-anti-MMR-VHH2 nanobody binds to MMR on tumor-associated macrophages (TAMs). Upon PET imaging, MMR-expressing TAMs can be visualized. MMR-expressing TAMs play a role in tumor growth and metastasis as well as immunotherapy resistance.