64Cu-SAR-bisPSMA PET/CT and Lesion Detection in Biochemical Recurrence

A press-release on the Co-PSMA Phase II investigator-initiated trial reports higher lesion and patient detection with 64Cu-SAR-bisPSMA PET/CT than with 68Ga-PSMA-11 PET/CT in men with biochemical recurrence after radical prostatectomy.

A cohort of 50 patients with prostate-specific antigen eligibility between 0.2 and 0.75 ng/mL was the setting for this head-to-head comparison. Co-PSMA was a within-participant comparison in the post-prostatectomy biochemical recurrence setting, with 68Ga-PSMA-11 PET/CT performed first and 64Cu-SAR-bisPSMA PET/CT performed within 3 weeks, including imaging at 1 hour (same-day) and 24 hours (next-day) post-injection. Participants were candidates for curative salvage therapy after radical prostatectomy.

For the study’s primary endpoint, the release reports mean lesions per patient of 1.26 with 64Cu-SAR-bisPSMA versus 0.48 with 68Ga-PSMA-11. The between-tracer difference was 0.78 (95% CI, 0.52–1.04), with a ratio of 2.63 (95% CI, 1.64–4.20).

Across all participants, the total lesion count is reported as 63 lesions detected on 64Cu-SAR-bisPSMA next-day imaging versus 24 lesions detected on 68Ga-PSMA-11. At the per-patient level, the release reports positivity rates of 78% (39/50) for 64Cu-SAR-bisPSMA and 36% (18/50) for 68Ga-PSMA-11. Among participants with an evaluable standard of truth, the true positive rate is reported as 75% (21/28) for 64Cu-SAR-bisPSMA compared with 39% (11/28) for 68Ga-PSMA-11.

Beyond detection, planned patient management changed after assessment with 64Cu-SAR-bisPSMA PET/CT in 22/50 participants.

Key Takeaways:

• Higher lesion and patient detection with 64Cu-SAR-bisPSMA PET/CT than with 68Ga-PSMA-11 were reported in a post-prostatectomy biochemical recurrence cohort.
• A change in planned management after 64Cu-SAR-bisPSMA assessment is reported in 22/50 participants.