Fifth patient achieves undetectable disease in SECuRE Phase II trial
Clarity Pharmaceuticals (ASX: CU6) has announced that another participant in the Phase II Cohort Expansion Phase of its SECuRE trial achieved undetectable disease following treatment with 67Cu-SAR-bisPSMA. The 76-year-old man, who had battled prostate cancer for 15 years, achieved undetectable prostate-specific antigen (PSA) after just one treatment cycle, with a negative prostate-specific membrane antigen (PSMA) positron emission tomography (PET) scan following the second cycle. This marks the fifth patient across Clarity Pharmaceuticals SECuRE trial results to reach undetectable disease status by radiographic assessment.
The participant entered the trial with a baseline PSA of 3.25 ng/mL after progressing to metastatic castration-resistant prostate cancer (mCRPC) in 2025. He received two cycles of 8 GBq 67Cu-SAR-bisPSMA each, achieving undetectable PSA at 7 weeks post-first cycle. All treatment-related adverse events were mild (Grade 1), including altered taste, dry eyes, eye pain, fatigue and salivary gland soreness, most of which resolved. Critically, no haematological or renal adverse events were observed, reinforcing the favourable safety profile of the therapy.
The speed and depth of response are particularly striking given the participant’s disease history. First diagnosed in 2010, he underwent radical prostatectomy and radiotherapy for local recurrence before progressing to metastatic disease in 2020. Previous systemic treatments included androgen receptor pathway inhibitors and androgen deprivation therapy. Despite this complex treatment history, 67Cu-SAR-bisPSMA delivered rapid and complete radiographic clearance.
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Understanding PSMA-targeted copper theranostics
SAR-bisPSMA is a targeted radiopharmaceutical that uses copper isotopes to both image and treat prostate cancer. The “bis” in its name refers to a novel structure connecting two PSMA-targeting agents to Clarity’s proprietary SAR chelator technology. This chelator securely holds copper isotopes inside a cage-like structure, preventing leakage into the body, a key advantage over commercially available alternatives.
The theranostic approach pairs copper-64 (64Cu) for imaging with copper-67 (67Cu) for therapy. 64Cu-SAR-bisPSMA identifies patients with PSMA-expressing lesions via PET imaging, enabling precise patient selection. Once identified, 67Cu-SAR-bisPSMA delivers targeted radiation to cancer cells expressing PSMA, a protein found on prostate cancer cells. This integrated diagnostic and therapeutic pathway streamlines treatment and enables clinicians to visualise response using the same molecular platform.
Undetectable PSA means the blood marker used to monitor prostate cancer has fallen below measurable levels, typically less than 0.1 ng/mL. A negative PSMA PET scan indicates no visible cancer lesions on imaging, representing the most stringent measure of treatment response. Together, these outcomes suggest the elimination of detectable disease.
The theranostic framework positions Clarity Pharmaceuticals (ASX: CU6) distinctively within the radiopharmaceutical sector, offering a unified platform from diagnosis through treatment that simplifies clinical workflows and potentially improves patient outcomes.
Previously reported patient maintains undetectable disease after fourth cycle
The participant announced on 15 January 2026, who achieved undetectable PSA after three cycles of 8 GBq 67Cu-SAR-bisPSMA, continues to show no detectable disease. His latest PET scan, conducted in February 2026 following a fourth treatment cycle, confirmed sustained complete radiographic response with PSA remaining undetectable.
This patient presented with bone metastasis at trial entry, a marker of advanced disease, yet now reports excellent quality of life. The durability of response over multiple cycles strengthens confidence in the treatment effect and provides important evidence for regulatory discussions ahead of Phase III planning. No new safety signals emerged during or after the fourth cycle, with all prior adverse events remaining mild (Grade 1), predominantly gastrointestinal, and no haematological or renal events.
Dr Alan Taylor, Executive Chairperson
“We are also excited to see that the previous participant in the Cohort Expansion Phase of the SECuRE trial to achieve undetectable disease observed by anatomical and molecular imaging continues to show undetectable disease during his last follow up in February 2026, following the fourth 67Cu-SAR-bisPSMA cycle. This is especially encouraging as this participant had bone metastasis at study entry and now continues to report excellent quality of life after his treatment with 67Cu-SAR-bisPSMA.”
The sustained response over multiple months provides preliminary evidence that the therapy’s effects may be durable, a critical consideration for patients with advanced mCRPC who typically face limited treatment options and progressive disease. These findings contribute to a growing body of Clarity Pharmaceuticals SECuRE trial results demonstrating consistent efficacy and safety.
Trial design and expansion phase progress
The SECuRE trial (NCT04868604) is a Phase I/IIa theranostic study evaluating 64Cu-SAR-bisPSMA for imaging and 67Cu-SAR-bisPSMA for treatment in participants with PSMA-expressing mCRPC. The trial is a multi-centre, single-arm study enrolling approximately 54 participants in the United States.
Following the Dose Escalation Phase (Phase I), which demonstrated a favourable safety profile and efficacy, the trial progressed to the Cohort Expansion Phase at the 8 GBq dose level based on Safety Review Committee recommendation. Participants in Cohort Expansion may receive up to 6 cycles of treatment.
| Trial Element | Detail |
|---|---|
| Trial Phase | Phase I/IIa (Cohort Expansion Phase active) |
| Dose Level | 8 GBq per cycle |
| Maximum Cycles | Up to 6 |
| Target Enrolment | ~54 participants (24 in Cohort Expansion) |
| Recruitment Completion | 2026 |
The Dose Escalation Phase reported high PSA response rates in the pre-chemotherapy setting: 92% of pre-chemotherapy participants (12/13) experienced PSA drops greater than 35%, 61.5% (8/13) achieved PSA reductions exceeding 50%, and 46.2% (6/13) reached PSA reductions of 80% or more. All three participants in Cohort 2, dosed at 8 GBq, achieved PSA declines of 80% or more (PSA80) with very low rates of related adverse events.
A subset of participants in the Cohort Expansion Phase will receive 67Cu-SAR-bisPSMA in combination with enzalutamide, an androgen receptor pathway inhibitor, aligning with positive results from the Enza-p trial and guidance from key prostate cancer specialists. Recruitment continues with planned completion in 2026.
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Phase III planning underway as clinical momentum builds
Clarity Pharmaceuticals (ASX: CU6) has confirmed that Phase III registrational trial planning for 67Cu-SAR-bisPSMA is ongoing, supported by the data generated to date. The company’s SAR-bisPSMA programme has received three Fast Track Designations from the US Food and Drug Administration (FDA), expediting the regulatory pathway. Positive interactions with the FDA confirm alignment on the development strategy, positioning the therapy for potential accelerated approval pathways.
Complementary diagnostic trials are nearing critical milestones:
- The AMPLIFY and CLARIFY registrational diagnostic trials evaluating 64Cu-SAR-bisPSMA are approaching recruitment completion, bringing the diagnostic component closer to commercialisation
- The Co-PSMA study reported that 64Cu-SAR-bisPSMA more than doubled prostate cancer lesion and patient detection compared to Ga-68 PSMA-11 in a head-to-head trial
- Three Fast Track Designations for SAR-bisPSMA products provide accelerated regulatory review potential
Dr Alan Taylor, Executive Chairperson
“Our registrational diagnostic AMPLIFY and CLARIFY trials with 64Cu-SAR-bisPSMA are also nearing the end of recruitment, getting us closer to commercialisation. We now look forward to progressing the SECuRE trial recruitment and have already initiated the planning for a registrational Phase III trial, as we hope to see more people benefit from our unique theranostic product. Having three Fast Track Designations (FTDs) for SAR-bisPSMA gives us confidence to persevere harder than ever, and positive interactions with the US Food and Drug Administration (FDA) confirm that we are on the right track.”
The convergence of positive therapeutic data from the SECuRE trial, advancing diagnostic trial programmes, and active Phase III planning represents multiple near-term catalysts for shareholders. The integrated theranostic platform positions Clarity to address the entire prostate cancer care pathway, from initial detection through late-stage metastatic disease, potentially creating a comprehensive commercial offering.
Addressing the prostate cancer treatment gap
Prostate cancer represents a substantial global health burden and a large addressable market. It is the second most commonly diagnosed cancer in men worldwide and the fifth leading cause of cancer death in men globally. In the United States, prostate cancer is the second-leading cause of cancer death among American men.
The American Cancer Society estimates approximately 333,830 new cases of prostate cancer will be diagnosed in the US in 2026, with around 36,320 deaths from the disease. These figures underscore the significant unmet medical need for effective therapies, particularly in advanced metastatic disease where treatment options remain limited and outcomes poor.
Clarity Pharmaceuticals’ SAR-bisPSMA platform targets the full disease continuum. 64Cu-SAR-bisPSMA enables early and accurate detection of prostate cancer recurrence, while 67Cu-SAR-bisPSMA provides targeted therapy for advanced and metastatic disease. This comprehensive approach addresses both diagnostic challenges and therapeutic gaps, positioning the company’s products across multiple stages of the patient journey.
The large patient population, combined with the demonstrated efficacy and safety profile in Clarity Pharmaceuticals SECuRE trial results, supports the commercial thesis for SAR-bisPSMA. With Phase III planning underway and regulatory engagement progressing, Clarity is advancing towards potential market entry in a sector characterised by significant clinical need and substantial commercial opportunity.
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