A novel targeted therapy known as ¹⁷⁷Lu-PSMA-617 significantly improved survival among patients with metastatic castration-resistant prostate cancer, according to findings presented at the 2021 ASCO Annual Meeting.

“This novel targeted radiotherapy could fill a significant need for patients with metastatic castration-resistant prostate cancer that has progressed despite chemotherapy and targeted antiandrogen therapy,” Lori J. Pierce, MD, FASTRO, FASCO, president of ASCO, said in a press release. “The success of this treatment highlights the importance of investigating alternatives to traditional types of cancer therapies.”

The therapy is “a radioactive compound that binds to prostate cancer cells expressing prostate-specific membrane antigen (PSMA) enabling targeted delivery of radiation to the tumor and surrounding microenvironment,” the announcement from ASCO said.

Michael J. Morris, MD, head of the Prostate Cancer Section at Sloan Kettering Cancer Center, New York, and colleagues performed a phase 3 international open-label trial of 831 patients with metastatic castration-resistant prostate cancer. Researchers randomly assigned patients at a 2:1 ratio to receive either standard of care and ¹⁷⁷Lu-PSMA-617 (n = 551) or standard of care alone (n = 280). The main outcomes were progression-free survival and overall survival.

All patients had previously undergone treatment with androgen receptor pathway inhibitors and 1–2 taxane chemotherapy regimens, and all were PSMA-positive. Median follow-up was 20.9 months.

Patients assigned to the novel therapy group demonstrated a median progression-free survival of 8.7 months, compared with 3.4 months in the standard of care group, the researchers reported (HR = 0.40; 99.2% CI, 0.29-0.57). Patients assigned to ¹⁷⁷Lu-PSMA-617 also demonstrated an improved median overall survival (15.3 vs. 11.3 months; HR = 0.62; 95% CI, 0.52-0.74).

Those assigned to the ¹⁷⁷Lu-PSMA-617 group experienced a higher rate of treatment-emergent adverse events (52.7% vs. 38%). Morris and colleagues reported that the drug was well-tolerated, however.

“The findings suggest that ¹⁷⁷Lu-PSMA-617 warrants consideration as a new standard of care in this patient population, pending regulatory review and approval,”Morris  said in the announcement.

Disclosures: Morris reports consulting or advisory roles with Advanced Accelerator Applications, Athenex, Bayer, Curium Pharma, Endocyte, Johnson & Johnson and ORIC Pharmaceuticals; research funding from Bayer (Inst), Corcept Therapeutics (Inst), Endocyte (Inst), Janssen (Inst), Progenics (Inst), Roche/Genentech (Inst) and Sanofi (Inst); and travel, accommodations and expenses from Endocyte and Fujifilm. Pierce reports stock and other ownership interests with PFS Genomics, and patents, royalties or other intellectual property with  PFS Genomics and UpToDate, as well as uncompensated relationships with Bristol-Myers Squibb and Exact Sciences.