Clarity Pharmaceuticals (ASX: CU6), a clinical-stage radiopharmaceutical company with a mission to develop next-generation products that improve treatment outcomes for patients with cancer, has provided a positive update on its SECuRE trial for 67Cu-SAR-bisPSMA in metastatic castration-resistant prostate cancer (mCRPC). The announcement details a preliminary assessment of the 8 GBq 67Cu-SAR-bisPSMA dose cohorts, which included 19 participants from both the Dose Escalation and Cohort Expansion phases of the study.
The preliminary assessment revealed significant efficacy, with 74% of evaluable participants achieving a PSA25 response (reductions of ≥25% in PSA), 63% achieving PSA50, 53% PSA75, and 26% PSA90. Furthermore, 81% of radiographically evaluable participants achieved disease control, comprising 50% stable disease and 31% complete response or undetectable disease. Importantly, two new participants in the Cohort Expansion phase achieved complete responses, bringing the total across the 67Cu-SAR-bisPSMA program to seven, with five of these observed in the 8 GBq dose cohorts. The patient population was challenging, with most participants having bone metastases and 79% having received five or more prior anti-cancer regimens.
Regarding safety, the 8 GBq dose level demonstrated a favourable profile. Most related adverse events (AEs) were mild or moderate (Grade 1/2) and transient, with common events including dry mouth and nausea. The prevalence and severity of related AEs observed in this group were generally lower compared to the overall trial population, and no Grade ≥4 related events were reported. The median number of treatment cycles was two, indicating significant anti-tumour activity after a small number of doses.
Clarity Pharmaceuticals continues recruitment into the Cohort Expansion Phase of the SECuRE trial, with ongoing planning for a Phase III registrational trial. These results underscore the potential of 67Cu-SAR-bisPSMA as a treatment option for mCRPC patients who have exhausted multiple lines of prior therapy, aiming to improve outcomes for a broader prostate cancer patient population.
