Clarity Pharmaceuticals has initiated the phase 2 Co-PSMA trial to compare its 64Cu-SAR-bisPSMA PET/CT imaging agent with the current standard-of-care 68Ga-PSMA-11 PET/CT for the detection of prostate cancer recurrence. The trial, conducted at St. Vincent’s Hospital in Sydney, Australia, seeks to determine if 64Cu-SAR-bisPSMA can more accurately detect sites of disease recurrence in patients with biochemical recurrence following radical prostatectomy. This comparative study could significantly impact the management of prostate cancer by improving the precision of salvage radiotherapy planning.
Co-PSMA Trial Design and Objectives
The Co-PSMA trial plans to enroll 50 patients who have experienced biochemical recurrence after radical prostatectomy and are being considered for curative salvage radiotherapy. The primary objective is to compare the detection rate of prostate cancer recurrence sites, measured by the number of lesions detected per patient, between 64Cu-SAR-bisPSMA and 68Ga-PSMA-11. Led by Dr. Louise Emmett, the trial aims to address the critical need for highly sensitive imaging techniques to accurately locate recurrence sites when prostate-specific antigen (PSA) levels begin to rise.
Clinical Significance and Current Landscape
Dr. Emmett emphasized the importance of accurate recurrence detection, stating, "Men with [biochemical recurrence] after radical prostatectomy have a window of opportunity for a cure with the use of external beam radiotherapy. In order to achieve that, we need to use highly sensitive imaging techniques that can accurately detect the site of disease recurrence when the prostate-specific antigen levels start to rise." The trial's findings could potentially improve patient outcomes by enabling more targeted and effective radiotherapy.
64Cu-SAR-bisPSMA: A Potential Advancement
64Cu-SAR-bisPSMA received fast track designation from the FDA in August 2024, highlighting its potential to address an unmet medical need in prostate cancer imaging. Previous data from Clarity Pharmaceuticals’ phase 1 PROPELLER trial (NCT04839367) demonstrated favorable safety and efficacy of 64Cu-SAR-bisPSMA in patients with untreated prostate cancer. The PROPELLER trial, which enrolled 30 patients undergoing radical prostatectomy and lymph node dissection, showed that 64Cu-SAR-bisPSMA was safe and well-tolerated, with a recommended dose of 200 MBq providing the highest imaging quality scores.
PROPELLER Trial Data
In the PROPELLER trial, 64Cu-SAR-bisPSMA exhibited higher SUVmax values compared to 68Ga PSMA-11 in patients receiving the 200 MBq dose. These results supported the initiation of the ongoing registrational phase 3 CLARIFY trial (NCT06056830), which is currently enrolling participants in the United States and Australia. The CLARIFY trial aims to enroll 383 adult patients with high-risk prostate cancer undergoing radical prostatectomy with pelvic lymph node dissection. The primary endpoint is the diagnostic performance of 64Cu-SAR-bisPSMA PET to detect regional nodal metastases prior to radical prostatectomy, assessed over 16 weeks, with final completion anticipated in February 2025.
