Hepatocellular carcinoma is the most common primary liver cancer and the fifth most frequently diagnosed cancer worldwide. Most patients with advanced disease are offered non-surgical palliative treatment options. This work explores the first α-emitting radioembolization for the treatment and monitoring of hepatic tumors. Furthermore, this works demonstrates the first in vivo simultaneous multiple-radionuclide SPECT images of the complex decay chain of an [225Ac]Ac-labeled agent using a clinical SPECT system to monitor the temporal distribution.
Methods: A DOTA chelator was modified with a lipophilic moiety and radiolabeled with Actinium-225. The resulting agent, [225Ac]Ac-DOTA-TDA, was emulsified in Lipiodol® and evaluated in vivo in mouse model and the VX2 rabbit technical model of liver cancer. SPECT imaging was performed to monitor distribution of the TAT agent and the free daughters.
Results: [225Ac]Ac-DOTA-TDA was shown to retain within the HEP2G tumors and VX2 tumor, with minimal uptake within normal tissue. In the mouse model, significant improvements in overall survival were observed. SPECT imaging was able to distinguish between the Actinium-225 agent (Francium-221) and the loss of the longer lived daughter, Bismuth-213.
Conclusion: A TAT agent emulsified in Lipiodol® is capable of targeting liver tumors with minimal accumulation in normal tissue, providing a potential therapeutic agent for the treatment of HCC as well as a variety of hepatic tumors. In addition, SPECT imaging presented here provides a foundation for imaging methodology and protocols that can be rapidly translated into the clinic to monitor Actinium-225-labeled agents.