PR21 Secondary Analysis Explores Treatment Sequencing in Advanced Prostate Cancer

Results from a pre-planned secondary analysis of the PR21 PLUDO trial were presented at ASCO 2026—providing insight into treatment sequencing for patients with metastatic castration-resistant prostate cancer (mCRPC). 

PR21 was a randomized phase II trial that compared Lutetium Lu-177 vipivotide tetraxetan (¹⁷⁷Lu-PSMA-617), a targeted radioligand therapy, with docetaxel chemotherapy in patients with PSMA-positive metastatic castration-resistant prostate cancer whose disease had progressed following hormone therapy. 

“In the initial report there was no difference in radiographic progression free survival but there appeared to be an advantage in using chemotherapy over ¹⁷⁷Lu-PSMA-617 in overall survival,” says Dr Fred Saad, Uro-oncologist at CHUM. “The original study was designed to detect a signal of improved cancer control using the targeted approach compared to standard chemotherapy.”

¹⁷⁷Lu-PSMA-617 is a newer form of targeted radioligand therapy designed to deliver high doses of radiation directly to prostate cancer cells while limiting damage to surrounding healthy tissue. 

“Patients in the primary study were given the option of crossing over to the other treatment allowing us to explore the effects of treatment sequencing,” says Dr Kim Chi, Medical Oncologist, BC Cancer – Vancouver, who delivered the oral presentation at the Genitourinary Cancer session. “Whether patients received ¹⁷⁷Lu-PSMA-617 followed by docetaxel or docetaxel followed by ¹⁷⁷Lu-PSMA-617 ^t, outcomes were similar.”  

The secondary analysis found that among patients who received both treatments sequentially, there was no significant difference in progression-free survival or overall survival both patient populations experienced similar outcomes. These results support both therapies as treatment options and may help clinicians make more personalized treatment decisions based on patient preferences and other biomarkers which still be studied in future research using tissue and imaging data collected during the trial.

“This emphasizes the importance of radiopharmaceutical therapy in clinical practice, adding a line of effective, well tolerated treatment that improves the outcome of prostate cancer patients,” says Dr François Bénard, Senior Executive Director, Research, BC Cancer. “Continued research in the field of radiopharmaceutical therapy, including personalized approaches to improve radiation dose delivery, next generation radiopharmaceuticals, and combination with other treatments will lead to further progress”