- The disease
- Prostate cancer is the most common cancer in men in many Western countries. After surgical removal of the prostate (prostatectomy) or radiation treatment, a rise in prostate-specific antigen (PSA) blood levels can indicate the cancer has returned — a state called biochemical recurrence (BCR). Locating where the cancer has returned is critical to guiding further treatment decisions. Positron emission tomography (PET) scans using agents that bind to PSMA, a protein highly expressed on prostate cancer cells, have become a standard imaging approach in this setting.
- What the asset is trying to do
- SAR-bisPSMA uses copper-64 (64Cu), a radioactive isotope, attached to a molecule designed to bind PSMA on prostate cancer cells. The 'bis' refers to the agent carrying two PSMA-binding units, which is intended to increase the time the agent stays attached to target cells compared with single-binding PSMA tracers. The copper-64 emits positrons that are detected by a PET scanner to produce images showing where PSMA-expressing cancer cells are located. The same carrier molecule can also be loaded with copper-67 (67Cu), a different isotope used for therapeutic (rather than imaging) purposes, as explored in the Phase 1/2 trial NCT04868604.
- What the trial is measuring, and why it matters
- The lead Phase 3 trial (NCT06970847) studies participants with BCR after prostatectomy or brachytherapy (seed implant radiation), enrolling 220 participants (per ClinicalTrials.gov NCT06970847). A second Phase 3 trial (NCT06056830) studies participants with high-risk prostate cancer before radical prostatectomy, enrolling 383 participants (per ClinicalTrials.gov NCT06056830). PET imaging trials in this setting typically measure the agent's ability to correctly identify cancerous lesions — endpoints such as correct localisation rate, sensitivity, and specificity are standard in regulatory submissions for diagnostic radiopharmaceuticals.
- Efficacy benchmarks in this setting
- In the BCR setting, 68Ga-PSMA-11 (Illuccix) received US FDA approval based on data from two prospective trials (OSPREY and CONDOR); in CONDOR, the correct localisation rate was 84% (95% CI 75-91%) for 68Ga-PSMA-11 versus 13% (95% CI 7-21%) for conventional imaging (per Akin-Akintayo et al, Journal of Nuclear Medicine 2022, and FDA prescribing information for 68Ga-PSMA-11). 18F-DCFPyL (Pylarify) also received FDA approval in BCR; in the OSPREY cohort B, the positive predictive value was 84.8% (95% CI 70.8-93.5%) (per Pienta et al, Journal of Nuclear Medicine 2021, and FDA prescribing information for 18F-DCFPyL). The Phase 2 head-to-head trial NCT06907641 compares 64Cu-SAR-bisPSMA directly against 68Ga-PSMA-11; figures from that ongoing study are not yet available, and any early-stage figures for SAR-bisPSMA are not statistically comparable to the approval datasets cited above.