Clarity Pharmaceuticals has announced positive preliminary data from its SECuRE trial, evaluating 67Cu-SAR-bisPSMA in patients with metastatic castrate-resistant prostate cancer (mCRPC). The Phase I/IIa trial (NCT04868604) is assessing the safety and efficacy of the theranostic agent in heavily pre-treated patients. Initial results from the first multi-dose cohort indicate a favorable safety profile and encouraging anti-cancer activity.
Multi-Dose Cohort Shows Encouraging Results
Cohort 4 of the SECuRE trial is the first to explore multiple cycles of 67Cu-SAR-bisPSMA at the highest dose of 12 GBq. Data from the first three participants showed no dose-limiting toxicities (DLTs). Most adverse events were mild to moderate and resolved quickly. Based on these findings, the Safety Review Committee (SRC) has approved the continuation of the trial with the remaining participants in the cohort, and pending their safety evaluation, the trial will proceed to the dose expansion phase with 14 participants.
Significant PSA Declines Observed
Efficacy data revealed that two patients who completed the DLT period experienced PSA declines greater than 60%. Notably, one patient, who had previously failed multiple lines of therapy, achieved a 92.3% reduction in PSA levels, with levels continuing to decline at the last assessment. This patient also demonstrated a radiographic partial response per RECIST v1.1, with a 60.6% reduction in tumor volume on PSMA-PET imaging.
Implications for Future Development
Dr. Alan Taylor, Executive Chairperson of Clarity Pharmaceuticals, stated that the positive safety profile of 67Cu-SAR-bisPSMA, especially compared to existing prostate cancer treatments, supports its potential use in earlier stages of the disease. The company is now planning clinical trials to focus on these earlier stages, while also addressing the unmet need in late-stage patients with high PSA levels who have failed multiple prior therapies.
The SECuRE trial utilizes 64Cu-SAR-bisPSMA to visualize PSMA-expressing lesions, enabling selection of appropriate candidates for 67Cu-SAR-bisPSMA therapy. The trial has enrolled approximately 44 patients across sites in the US and Australia. Participants in cohort 4 received between two and four treatment cycles of 67Cu-SAR-bisPSMA at 12 GBq, while previous cohorts received ascending single doses.
