SNMMI 2019: Phase I/II Trial of Lutetium-177–PSMA-617 Plus Idronoxil in Metastatic Castration-Resistant Prostate Cancer
A novel therapy using two targeted treatments for prostate cancer has been shown to maximize efficacy while reducing side effects, according to research presented at the 2019 Annual Meeting of the Society of Nuclear Medicine and Molecular Imaging (SNMMI) and published by Emmett et al in The Journal of Nuclear Medicine.
Trials with the targeted radionuclide therapy lutetium-177 PSMA-617 (LuPSMA) have proven safe and effective in some men with metastatic castration-resistant prostate cancer; however, not all respond to treatment, and responses may be limited in duration. To build upon these trials, researchers paired LuPSMA with the tumor-specific radiation sensitizer idronoxil (NOX66) to assess responses in patients with heavily treated metastatic castration-resistant prostate cancer.
Methods
The phase I/II trial enrolled 16 men with pretreated, progressive metastatic castration-resistant prostate cancer. All men received up to six doses of LuPSMA at 6-week intervals. Half the patients (cohort 1) received additional treatment of 400 mg NOX66 daily for 10 days. Following a safety data review, the remaining patients (cohort 2) received additional treatment of 800mg NOX66 daily.
Results
Researchers found that nearly 70% of all patients saw a more than a 50% reduction in their prostate-specific antigen levels (62.5% in cohort 1 and 75% in cohort 2) after the combination treatment. Adverse side effects, such as fatigue and pneumonitis, were reported in 31% of all patients (37.5% in cohort 1 and 12.5% in cohort 2).
“The initial results of this phase I dose escalation study show that the combination targeted treatments were well tolerated together, with no increase in toxicity from LuPSMA, and an apparent high efficacy in men who have already had extensive treatments,” said Louise Emmett, MD, Associate Professor at the University of New South Wales in Sydney, Australia.
She continued, “We are now in a dose-expansion phase II stage to further evaluate toxicity and efficacy. This raises the very important possibilities of combining tumor-targeted therapeutic agents to gain synergistic treatment effects without an increase in side effects.”
Disclosure: For full disclosures of the study authors, visit jnm.snmjournals.org.
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