64Cu-SAR-bisPSMA Bests SOC 68Ga-PSMA-11 PET/CT in Detecting PSMA-Positive Prostate Cancer Lesions

The phase 2 Co-PSMA trial (NCT06907641) has achieved its primary end point, displaying a significantly higher proportion of prostate-specific membrane antigen (PSMA)–positive prostate cancer lesions detected using ⁶⁴Cu-SAR-bisPSMA compared with standard-of-care (SOC) ⁶⁸Ga-PSMA-11 PET/CT in patients with low prostate-specific antigen (PSA) levels.¹

The topline findings support the hypothesis that SAR-bisPSMA, a targeted copper theranostic that can be used with isotopes of copper-64 for imaging and copper-67 for therapy, can improve early detection of prostate cancer recurrence and staging in patients with low PSA levels who are candidates for curative salvage therapy. A complete analysis of the full data generated in Co-PSMA is ongoing and further findings from the trial will be presented at an upcoming international medical conference.

“Achieving the primary end point in the Co-PSMA trial, which was a head-to-head trial against a SOC competing product, is yet another important step in the development of ⁶⁴Cu-SAR-bisPSMA as we look to further validate this agent as best-in-class through two registrational trials with 2 fast track designations under our belt for diagnostic applications and a strong focus on commercialization,” Alan Taylor, PhD, the executive chairperson of Clarity Pharmaceuticals, stated in a news release.

In August 2024, ⁶⁴Cu-SAR-bisPSMA received fast track designation from the FDA for the PET evaluation of patients with PSMA-positive prostate cancer lesions with suspected metastasis who are candidates for initial definitive therapy.² In January 2025, the theranostic received fast track designation from the FDA for the PET evaluation of patients with PSMA-positive prostate cancer lesions with biochemical recurrence of prostate cancer after definitive therapy.³

What Prior Data Have Been Reported With ⁶⁴Cu-SAR-bisPSMA?

⁶⁴Cu-SAR-bisPSMA was also evaluated in the phase 1/2 COBRA study (NCT05249127), which examined the theranostic in patients with prostate cancer who experienced biochemical recurrence after definitive therapy.⁴ Findings from the trial revealed that ⁶⁴Cu-SAR-bisPSMA led to a change in intended treatment plan in 48% of efficacy evaluable patients (n = 32). Moreover, the approach was found to be safe with only 1 adverse effect being related to ⁶⁴Cu-SAR-bisPSMA, which was a grade 2 instance of worsening of type 2 diabetes that resolved.

What Was the Design of the Co-PSMA Trial?

Co-PSMA enrolled male patients who were at least 18 years old who underwent radical prostatectomy for confirmed adenocarcinoma.⁵ Eligible patients also needed to have rising PSA levels (0.20 ng/mL to 0.75 ng/mL) following radical prostatectomy with no prior salvage radiotherapy and have received ⁶⁸Ga PSMA-11 PET/CT within the past 4 weeks for prostate cancer biochemical recurrence. All patients received a single administration of ⁶⁴Cu-SAR-bisPSMA at 200 MBq.

“We look forward to [releasing] the full Co-PSMA trial data at world-leading congresses as we continue to adhere to the highest standards of clinical research in our aspirations to bring a best-in-class diagnostic option to men with prostate cancer with clear evidence of superiority,” Taylor added in the news release.¹

The primary end point was the detection rate of lesions per participants between ⁶⁴Cu-SAR-bisPSMA and ⁶⁸Ga PSMA-11 PET/CT in patients with biochemical recurrence following radical prostatectomy who are being considered for curative salvage radiotherapy.⁵ Secondary end points included comparing ⁶⁴Cu-SAR-bisPSMA and ⁶⁸Ga PSMA-11 PET/CT in terms of the number of lesions outside of the prostatic fossa per patient, diagnostic accuracy, the magnitude of clinical management change, and the number of total lesions at the 1-to-4, and 24-hour imaging timepoints.

“We have already seen in the first-in-human PROPELLER trial [NCT04839367] an improved diagnostic performance of ⁶⁴Cu-SAR-bisPSMA compared [with] ⁶⁸Ga-PSMA-11 on same-day imaging, including a higher number of lesions identified and 2 [to] 3 times higher tumor uptake and tumor-to-background ratio,” Taylor said.¹ “We then showed in the COBRA trial that approximately twice the amount of lesions was identified on ⁶⁴Cu-SAR-bisPSMA PET on next-day vs same-day imaging, and vs SOC PSMA PET. ⁶⁴Cu-SAR-bisPSMA also allowed for the identification of lesions in the 2-mm range, something that SOC PSMA PET agents often fail to achieve. This improvement was driven by a substantially increased tumor-to-background ratio and lesion uptake over time with next-day imaging.”

References

1. Co-PSMA trial achieves primary endpoint. News release. Clarity Pharmaceuticals. October 14, 2025. Accessed October 14, 2025. https://www.claritypharmaceuticals.com/news/co-psma-endpoint/
2. Clarity receives FDA fast track designation for 64Cu-SAR-bisPSMA. News release. Clarity Pharmaceuticals. October 14, 2025. Accessed October 14, 2025. https://www.claritypharmaceuticals.com/news/fast-track/
3. Clarity receives U.S. FDA fast track designation for Cu-64 SAR-bisPSMA in biochemical recurrence of prostate cancer. News release. Clarity Pharmaceuticals. January 24, 2025. Accessed October 14, 2025. https://www.claritypharmaceuticals.com/news/ftd-2/
4. Nordquist L, Lengyelova E, Saltzstein D, et al. COBRA: assessment of safety and efficacy of 64Cu-SAR-bisPSMA in patients with biochemical recurrence of prostate cancer following definitive therapy. J Nucl Med. 2024;65(suppl 2):242291.
5. Comparative performance of 64Copper [64Cu]-SAR-bis-PSMA vs 68Ga PSMA-11 PET CT for the detection of prostate cancer recurrence in the setting of biochemical failure following radical prostatectomy (Co-PSMA). ClinicalTrials.gov. Updated April 2, 2025. Accessed October 14, 2025. https://clinicaltrials.gov/study/NCT06907641