Thermoresponsive polymeric radionuclide delivery system--an injectable brachytherapy

Area of Science:

• Oncology
• Radiotherapy
• Biomedical Engineering

Background:

• Brachytherapy offers targeted radiation for solid tumors, minimizing systemic exposure.
• Injectable brachytherapy aims to enhance ease of administration and patient tailoring compared to traditional implantation methods.

Purpose of the Study:

• To evaluate the efficacy of injectable intratumoral brachytherapy using iodine-131-labeled thermoresponsive polymer in a murine prostate cancer model.
• To assess the dose-dependent effects of this novel brachytherapy system on tumor growth and potential side effects.

Main Methods:

• A single dose of injectable intratumoral brachytherapy with iodine-131-labeled poly(N-isopropyl acrylamide) was administered to murine xenografts (PC3 human prostate adenocarcinoma).
• Two doses were tested: 2 MBq/mouse and 25 MBq/mouse.
• Tumor volume and signs of inflammation were monitored.

Main Results:

• The higher dose (25 MBq/mouse) resulted in significant tumor volume reduction, with 2 out of 6 mice achieving complete tumor eradication (cures).
• The lower dose (2 MBq/mouse) demonstrated statistically significant tumor growth retardation compared to controls.
• No signs of inflammation were observed in either treatment group.

Conclusions:

• Injectable iodine-131-labeled thermoresponsive polymer brachytherapy shows significant dose-dependent efficacy in reducing solid tumors.
• This approach offers a less invasive, potentially patient-tailored alternative to conventional brachytherapy.
• Further research into this bioerodable injectable system is warranted for clinical oncology applications.