Targeted Radionuclide Therapy for Metastatic Castration-Resistant Prostate Cancer
Posted: Friday, July 12, 2019
For men diagnosed with metastatic castration-resistant prostate cancer, the addition of the tumor-specific radiation sensitizer idronoxil with the targeted radionuclide therapy lutetium-177–PSMA-617 appears to be safe and active, according to the phase I/II trial findings presented at the 2019 Society of Nuclear Medicine and Molecular Imaging (SNMI) Annual Meeting in Anaheim (Abstract 465) and published in The Journal of Nuclear Medicine. Louise Emmett, MD, of Monash University and the Peter MacCallum Cancer Centre, Melbourne, Australia, and colleagues found that the combination seemed particularly effective in men who had already underwent extensive treatment for prostate cancer.
“We are now in a dose-expansion phase II stage to further evaluate toxicity and efficacy,” Dr. Emmett said in an SNMMI press release. “This raises the very important possibilities of combining tumor-targeted therapeutic agents to gain synergistic treatment effects without an increase in side effects.”
In this phase I/II trial, the authors enrolled 16 men with metastatic castration-resistant prostate cancer that progressed despite being treated with docetaxel, cabazitaxel, and either abiraterone or enzalutamide. Each patient received up to 6 doses of lutetium-177–PSMA-617 every week for 6 weeks. Additionally, eight men were treated daily with 400 mg of idronoxilfor 10 days. Subsequently, after investigators reviewed the safety profiles among the enrolled men, the eight other patients received daily doses of 800 mg of idronoxil.
Nearly 70% of all the patients enrolled demonstrated a more than 50% reduction in their prostate-specific antigen (PSA) levels. Specifically, 62.5% of the men who received 400 mg of idronoxiland 75% of the men who received 800 mg of idronoxilexperienced a reduction in PSA levels. In the former group, 37.5% of the patients reported adverse side effects such as fatigue or pneumonitis, whereas 12.5% of the men in the latter group reported those same side effects.
Disclosure: The study authors’ disclosure information can be found at jnm.snmjournals.org
