MMP9 and neoplasm: Even though the Cu (II)-DOTA-CTT inhibited MMP2 and MMP9 activities with binding affinities (EC50) of 8.7 μM and 18.2 μM, respectively, which are very similar to those of the original CTT (13.2 μM and 11.0 μM, respectively), it was not successful in in vivo tumor imaging [210].