(UroToday.com) The 2025 GU ASCO annual meeting featured a prostate cancer trials in progress session and a presentation by Michael Gorin discussing CLARIFY, a phase 3 diagnostic performance study assessing PET using 64Cu-SAR-bisPSMA in patients with high-risk prostate cancer prior to radical prostatectomy. Prostate cancer is the second most prevalent cancer in men globally. In men with newly diagnosed, high-risk disease, prostate cancer most often spreads to the pelvic lymph nodes before becoming widely metastatic. PSMA is a type II transmembrane glycoprotein that is strongly overexpressed in prostate cancer, making it an ideal target for imaging and therapy. Current PSMA PET agents have high specificity, but low sensitivity for the detection of pelvic lymph node involvement. 64Cu-SAR-bisPSMA may offer several advantages over the currently approved PSMA PET agents due to its bivalent structure (SAR-bisPSMA) and longer half-life of 64Cu (12.7 hours versus <2 hours for 18F and 68Ga):
In the phase 1 PROPELLER study, 64Cu-SAR-bisPSMA demonstrated 2-3 times higher tumor uptake, prolonged retention, and detection of additional prostate cancer lesions compared to approved PSMA agents:
This phase 3 diagnostic trial aims to establish the diagnostic performance of 64Cu-SAR-bisPSMA PET to detect regional nodal metastases in men with high-risk prostate cancer.
CLARIFY (NCT06056830) is a multi-center, single-arm, non-randomized, open-label phase 3 diagnostic study of 64Cu-SAR-bisPSMA. The target population is patients with untreated, histopathology-confirmed prostate cancer with high-risk features, who are proceeding to radical prostatectomy with pelvic lymph node dissection. The primary endpoint is to assess the sensitivity and specificity of 64Cu-SAR-bisPSMA PET to detect pelvic nodal metastases. Secondary objectives include assessment of safety and determining the positive and negative predictive value of 64Cu-SAR-bisPSMA PET. A total of 383 patients will be enrolled. Standard of care imaging will be acquired at screening (ie. computed tomography, approved PSMA PET/CT).
Eligible patients will receive a single administration of 64Cu-SAR-bisPSMA (200 MBq) followed by a PET/CT scan on Day 1 (1-4 hours post-dose, same-day imaging) and on Day 2 (24 ± 6 hours post-dose, next-day imaging). Patients will then proceed to radical prostatectomy with pelvic lymph node dissection. The specimens from surgery will be processed and analyzed locally to derive the standard of truth:
The 64Cu-SAR-bisPSMA PET/CT scans will be interpreted locally and by 3 independent, blinded, central readers. Each reader will assess the scans for the presence of abnormal 64Cu-SAR-bisPSMA uptake in the pelvic lymph nodes, prostate gland, extra-pelvic lymph nodes, visceral/soft tissue, and bone. The diagnostic performance of 64Cu-SAR-bisPSMA will be based on the PET result on the respective day independently (Day 1 and 2) matched against the standard of truth. The study is currently open for recruitment in sites in the United States and in Australia:
Presented by: Michael A. Gorin, MD, Mount Sinai, New York, NY
Written by: Zachary Klaassen, MD, MSc – Urologic Oncologist, Associate Professor of Urology, Georgia Cancer Center, Wellstar MCG Health, @zklaassen_md on Twitter during the 2025 Genitourinary (GU) American Society of Clinical Oncology (ASCO) Annual Meeting, San Francisco, CA, Thurs, Feb 13 – Sat, Feb 15, 2025.