Calcium Carbonate Microparticles as Carriers of 224 Ra: Impact of Specific Activity in Mice with Intraperitoneal Ovarian Cancer

Background: Patients with advanced-stage ovarian cancer face a poor prognosis because of recurrent peritoneal cavity metastases following surgery and chemotherapy. Alpha-emitters may enable the efficient treatment such disseminated diseases their short range highly energetic radiation. Radium-224 is candidate ?-emitter due to its convenient 3.6-day half-life, more than 90% decay energy originating from ?-particles. However, inherent skeletal accumulation must be overcome facilitate intraperitoneal delivery radiation dose. Therefore, 224 Ra-labeled CaCO 3 microparticles have been developed. Objective: The antitumor effect as carrier for Ra was investigated, an emphasis on ratio activity mass dose , that is, specific activity. Methods: Nude athymic mice were inoculated intraperitoneally human cells (ES-2) treated single injection varying combinations dose, or cationic in solution. Survival ascites volume at sacrifice evaluated. Results: Significant therapeutic achieved all tested activities ranging 0.4 4.6 kBq/mg. Although mean 1305 kBq/kg prolonged survival compared control, equivalent median could only 420 kBq/kg. best outcome highest (2.6 kBq/mg). Conclusion: Radium-224-labeled present promising therapy against dissemination body cavities.