Phase 2: Copper-Based PET Imaging Agent Surpasses Standard Tracer for Early Prostate Cancer Lesion Detection

The phase 2 Co-PSMA trial conducted at St Vincent’s Hospital in Sydney evaluated 64Cu-SAR-bisPSMA, a novel copper-based PET imaging agent, against the standard 68Ga-PSMA-11 tracer in patients with biochemical recurrence of prostate cancer and low PSA levels.

Results showed 64Cu-SAR-bisPSMA detected a statistically greater number of PSMA-positive lesions per patient than the standard agent, particularly enhancing detection of disease recurrence and staging for candidates of curative salvage therapy. The agent’s performance was further validated through increased sensitivity on delayed imaging, with next-day imaging revealing nearly double the number of lesions compared to same-day imaging or standard PET agents.

In comparative trials such as COBRA, 64Cu-SAR-bisPSMA identified lesions up to six months sooner than the standard of care, often detecting tumors as small as 2 mm. These advances are attributed to the agent’s longer half-life and dual PSMA-targeting design using a proprietary SAR chelator technology, which is also assessing 64Cu-SAR-bisPSMA in the larger phase 3 CLARIFY and AMPLIFY trials.

Unlike ⁶⁸Ga-based agents, which have a short half-life limiting imaging flexibility, copper-64’s longer half-life (12.7 hours) allows for delayed imaging and improved lesion contrast. This enables ⁶⁴Cu-SAR-bisPSMA PET/CT to detect smaller or earlier recurrent tumors missed by conventional imaging methods. In same-day imaging, the tracer identified 26.3 total lesions across all reads, which increased to 52.6 lesions with next-day imaging—compared with only 20 detected via standard ⁶⁸Ga-PSMA-11 scans.

⁶⁴Cu-SAR-bisPSMA currently holds two FDA Fast Track Designations, for detection of suspected metastasis (August 2024) and biochemical recurrence (January 2025) reflecting its potential to fill a major diagnostic need in prostate cancer imaging.

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