Trial of 64Cu/67Cu SAR-bisPSMA progresses following positive data
No dose-limiting toxicities were observed among the initial 3 patients in cohort 3, and no patients experienced adverse events related to 64Cu-SAR-bisPSMA.
The Safety Review Committee has recommended progression of the phase 1/2 SECuRE trial (NCT04868604) exploring 64Cu/67Cu SAR-bisPSMA in patients with metastatic castrate-resistant prostate cancer (mCRPC) following positive data from the initial 3 patients enrolled in cohort 3, who are being treated at the highest dose level of 12GBq, announced Clarity Pharmaceuticals, the developer of the products, in a news release.1
Recruitment of the additional 3 participants for cohort 3 of the study has opened across clinical sites in the US.
According to the release, no dose-limiting toxicities were observed among the initial 3 patients in cohort 3, and no patients experienced adverse events (AEs) related to 64Cu-SAR-bisPSMA. Only 1 patient experienced an AE related to treatment with 67Cu-SAR-bisPSMA, which was a grade 1 reduction in neutrophil count. The patient has fully recovered.
Additionally, 2 of the 3 participants experienced a reduction in prostate-specific antigen (PSA) levels within weeks following single dose administration of 12GBq 67Cu-SAR-bisPSMA. At the time of data report, 1 patient had experienced a greater than 90% reduction in PSA, and the other had experienced an approximately 40% reduction in PSA.
Given the SECuRE trial’s 3+3 design, the Safety Review Committee has recommended that the trial continue with the 3 additional patients in cohort 3 as planned.
"A number of patients from the SECuRE trial have either received, or will soon receive, additional doses of 67Cu-SAR-bisPSMA under the US Food and Drug Administration's (FDA) Expanded Access Program (EAP). This demonstrates the initial clinical benefit observed in such patients after the administration of a single cycle of the product during the trial,” said Executive Chairperson for Clarity Pharmaceuticals Alan Taylor, PhD, in the news release.1
The SECuRE trial is a multicenter, single-arm, dose escalation study to assess the safety and efficacy of 67Cu-SAR-bisPSMA following detection of PSMA-expressing lesions with 64Cu-SAR-bisPSMA.2 The trial includes patients with mCRPC who have progressed following treatment with androgen deprivation therapy and at least 1 second-generation androgen receptor pathway inhibitor, such as abiraterone acetate (Zytiga) or enzalutamide (Xtandi).
Cohort 3 of the SECuRE trial is the last to assess 67Cu-SAR-bisPSMA administered in single doses. Pending safety evaluations from the additional 3 participants in the cohort, the trial will progress to multi-dose cohort explorations. All 3 initial participants in cohort 3 remain on trial.
Recruitment of the additional 3 participants for cohort 3 of the study has opened across clinical sites in the US.
Taylor concluded in the news release, "As we have seen PSA reductions in the majority of patients after a single cycle of 67Cu-SAR-bisPSMA across all dose levels, which is known to be an independent prognostic indicator of improved overall survival following radio-ligand therapy, we hope to achieve long-term and durable responses once we progress to the multi-dose cohorts of the trial. Furthermore, with commercial quantities of the 67Cu radioisotope now being routinely produced domestically in the US, we see a clear path to commercialization as we can resolve the supply and manufacturing issues which have plagued the commercial launch of first-generation products. We look forward to sharing more data along with any further updates from patients who may receive single or multiple cycles of 67Cu-SAR-bisPSMA in our programs and bringing this product to the greater prostate cancer patient population.”1
References
1. Clarity’s theranostic prostate cancer trial progresses at the highest dose level cohort. News release. Clarity Pharmaceuticals. Published online and accessed November 29, 2023. https://www.prnewswire.com/news-releases/claritys-theranostic-prostate-cancer-trial-progresses-at-the-highest-dose-level-cohort-302000099.html
2. 64Cu-SAR-bisPSMA and 67Cu-SAR-bisPSMA for Identification and Treatment of PSMA-expressing Metastatic Castrate Resistant Prostate Cancer (SECURE). ClinicalTrials.gov. Last updated May 24, 2023. Accessed November 29, 2023. https://clinicaltrials.gov/ct2/show/NCT04868604
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