The evaluations of 99mTc cyclopentadienyl tricarbonyl triphenyl phosphonium cation for multidrug resistance

A triphenylphosphonium cation, ^99mTc]Technetium cyclopentadienyltricarbonyl-6-hexanoyl-triphenylphosphonium cation (^99mTc]3) was prepared to target multidrug resistance (MDR). The radiotracer was evaluated in the MDR-negative MCF-7 and MDR-positive MCF-7/ADR cell lines in vitro, as well as animal models in vivo. ^99mTc]3 was proofed to be a substrate of P-glycoprotein and multidrug resistant protein 1, and showed a higher accumulation in the MDR-negative MCF-7 cells compared to ^99mTc-sestamibi in vitro. The MCF-7 tumor-to-MCF-7/ADR tumor ratio of ^99mTc]3 was ～3 at 1 h p.i. in the biodistribution study. These results demonstrated the capability of the radiotracer to detect multidrug resistance in tumor cells.