Design and synthesis of tumor-targeting theranostic drug conjugates for SPECT and PET imaging studies

Theranostics will play a significant role in the next-generation chemotherapy. Two novel tumor-targeting theranostic drug conjugates, bearing imaging arms, were designed and synthesized. These theranostic conjugates consist of biotin as the tumor-targeting moiety, a second generation taxoid, SB-T-1214, as a potent anticancer drug, and two different imaging arms for capturing ^99mTc for SPECT (single photon emission computed tomography) and ⁶⁴Cu for PET (positron emission tomography). To explore the best reaction conditions for capturing radionuclides and work out the chemistry directly applicable to “hot” nuclides, cold chemistry was investigated to capture ¹⁸⁵Re(I) and ⁶³Cu(II) species as surrogates for ^99mTc and ⁶⁴Cu, respectively.