- 01SECuRE hit its 16-patient main-group target at 8GBq.
- 02Enzalutamide arm recruitment continues.
- 03Prior data: 74% had ≥25% PSA decline; Phase III planned.
Clarity Pharmaceuticals (ASX: CU6) has reached the recruitment target for the Main Group of the Cohort Expansion in its Phase I/IIa SECuRE trial evaluating 67Cu-SAR-bisPSMA in metastatic castration-resistant prostate cancer (mCRPC).
Sixteen participants have been enrolled in the Main Group and are being assessed for the efficacy and safety of up to six treatment cycles at a dose of 8 gigabecquerels (GBq).
Recruitment is continuing for additional participants who will receive 8GBq of 67Cu-SAR-bisPSMA in combination with enzalutamide, an androgen receptor pathway inhibitor (ARPI).
The Cohort Expansion is designed to assess the therapy in 24 mCRPC participants before taxane or radioligand-based therapies, with Clarity also planning a registrational Phase III trial based on preliminary results.
Clarity expects to release further updates as data from recently enrolled participants mature while it continues collecting data across the cohort and evaluating the potential additional benefit of the enzalutamide combination.
Trial Recruitment Milestone
The Main Group milestone follows completion of the SECuRE Dose Escalation phase, which treated 21 participants before the trial progressed into Cohort Expansion at the 8GBq dose level on the recommendation of its Safety Review Committee.
A multi-centre, single-arm trial planning to enrol about 54 participants in the US, SECuRE is using 64Cu-SAR-bisPSMA to visualise prostate-specific membrane antigen (PSMA)-expressing lesions before selected participants receive 67Cu-SAR-bisPSMA therapy.
The expansion phase is structured to include about eight participants receiving 67Cu-SAR-bisPSMA alone and about 16 receiving the treatment with enzalutamide, with recruitment into the combination arm continuing.
“Reaching the recruitment target in the Main Group of the SECuRE study is a significant milestone in the development of this promising theranostic product,” executive chair Alan Taylor said.
“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.”
Efficacy Data to Guide Next Steps
Data previously reported from 19 participants treated at the 8GBq level showed substantial declines in prostate-specific antigen (PSA), with 74% of evaluable participants achieving at least a 25% reduction from baseline and 63% achieving at least a 50% reduction.
The same dataset showed 53% achieved at least a 75% PSA reduction and 26% achieved at least a 90% decline, while 81% of 16 radiographically evaluable participants achieved disease control.
That disease-control result comprised 50% with stable disease and 31% with complete response or undetectable disease, while seven participants across the broader 67Cu-SAR-bisPSMA clinical development program had achieved complete response or undetectable disease.
Most related adverse events were reported as mild or moderate and transient, although 67Cu-SAR-bisPSMA and 64Cu-SAR-bisPSMA remain unregistered products whose safety and efficacy have not been assessed by health authorities.
Clarity is continuing to develop SAR-bisPSMA as a Targeted Copper Theranostic platform using copper-64 for imaging and copper-67 for therapy, with the SECuRE program intended to establish the safety and efficacy of the therapeutic component in prostate cancer.
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