Clarity Pharmaceuticals has reached its recruitment target for the main group of the expansion phase of its SECuRE trial, and says it is already planning a registrational Phase 3 study of its copper isotope therapy for advanced prostate cancer.
The company announced that sixteen men with metastatic castration-resistant prostate cancer have now been enrolled in the main group of the trial's Cohort Expansion. Each will receive up to six cycles of 8 GBq of 67Cu‑SAR‑bisPSMA while investigators assess how well the experimental treatment works and how safe it is.
The expansion will eventually include 24 patients who have not yet received taxane chemotherapy or radioligand therapy. About eight of them will receive the drug alongside enzalutamide, an androgen receptor pathway inhibitor, and recruitment into that arm is continuing. Clarity said the combination follows positive results from the ENZA‑p trial and advice from leading prostate cancer experts worldwide.
The most recent efficacy data, reported from 19 participants, showed that a median of two cycles at the 8 GBq dose produced substantial falls in prostate-specific antigen, the blood marker used to track the disease. Among evaluable participants, 74 per cent recorded a fall of at least 25 per cent, 63 per cent a fall of at least half, 53 per cent a fall of at least three quarters and 26 per cent a fall of at least 90 per cent.
Of the 16 participants who could be assessed on imaging at that dose, 81 per cent achieved disease control. Half had stable disease and 31 per cent had a complete response or undetectable disease. Across the whole 67Cu‑SAR‑bisPSMA program, seven participants have now reached that point. Most treatment-related adverse events were mild or moderate and short-lived, the company said.
Clarity's Executive Chairperson, Dr Alan Taylor, said, "Our SAR-bisPSMA programs continue to generate an impressive evidence base in clinical trials and real-world case profiles. As our two registrational diagnostic trials are nearing readouts early next year, we look forward to further leveraging the benefits of the bivalent PSMA molecule as well as of the 'perfect pairing' of copper isotopes to explore the positive impact our product could make in the treatment of mCRPC, an area of focus for us as we look to develop a product with key advantages over standard-of-care. Reaching the recruitment target in the Main Group of the SECuRE study is a significant milestone in the development of this promising theranostic product."
SAR‑bisPSMA joins two molecules that target PSMA, a protein found on prostate cancer cells, to a cage‑like structure that holds copper securely and stops it leaking into the body. Copper‑64 is used to find tumours on scans and copper‑67 is used to treat them. In SECuRE, the imaging version picks out patients whose cancer is likely to respond before they receive the therapy.
Dr Taylor said the results so far were encouraging enough to start planning the next stage. "With a total of 16 patients enrolled in the main group of the Cohort Expansion (multi-dose), as well as 21 participants treated in the Dose Escalation phase, we have observed strong efficacy with a favourable safety profile of 67Cu-SAR-bisPSMA. We are inspired and motivated to progress our theranostic program as almost a third of all evaluable patients treated at the 8 GBq dose level had achieved undetectable levels of disease and/or complete response across the 67Cu-SAR-bisPSMA program at the date of the last assessment (20 July 2026). While we continue to collect data from the enrolled participants and to recruit into the enzalutamide arm to explore the potential further benefits of this combination with 67Cu-SAR-bisPSMA, we are already in planning for a registrational theranostic Phase III trial based on the preliminary results."
"We look forward to providing a further update on the SECuRE trial shortly as our team and collaborators continue to generate a compelling body of high-quality data, advancing SAR-bisPSMA towards commercialisation, as we believe this unique molecule could improve the outcomes for prostate cancer patients across multiple stages of disease, from accurate lesion detection in the pre-prostatectomy and biochemical recurrence (BCR) settings through to treatment in mCRPC," Dr Taylor added.
