MMP9 and neoplasm: 64Cu-DOTA-CTT was found to inhibit MMP-2 (EC50 = 8.7 μM) and MMP-9 (EC50 = 18.2 μM) with similar affinity as CTT (EC50 = 13.2 and 11.0 μM, respectively), but in vivo was a poor tumor imaging agent due to its low affinity and instability [51].