Radionuclide therapy using nanoparticle of 131I-Lactosome in combination with percutaneous ethanol injection therapy

We present here a radionuclide therapy using nanoparticle of 131I-labeled Lactosome (131I-Lactosome) is effective as a tumor therapy when combined with the local therapy of the percutaneous ethanol injection therapy (PEIT). A mixture of 131I-labeled poly(l-lactic acid)30 and amphiphilic block polymer of poly(sarcosine)64-block-poly(l-lactic acid)30 was dispersed in saline to generate polymeric micelles of 131I-Lactosome (the diameter of 46 nm with PDI of 0.057). Mice were transplanted with murine mammary cancer (4T1) cells, and a relatively small amount of ethanol was injected percutaneously to the tumor region, followed by intravenous administration of 131I-Lactosome (2.0 × 102 MBq/kg). At 16 days after the 131I-Lactosome dosage with PEIT, the relative tumor volume (RTV) was suppressed as low as 5.32 ± 1.06, while the RTV values became significant to be 15.9 ± 5.0 with PEIT alone and 17.4 ± 3.9 with 131I-Lactosome alone. Indeed, 131I-accumulation in the transplanted tumor region at 48 h after 131I-Lactosome dosage became three times higher with PEIT than that without PEIT. The nanoparticle-based radionuclide therapy in combination with PEIT was, therefore, effective in suppression of tumor proliferation.