Clarity Pharmaceuticals Completes Dosimetry Phase of SAR-bisPSMA Theranostic Trial for Metastatic Prostate Cancer
Key Insights
Clarity Pharmaceuticals (search) has completed recruitment for the initial dosimetry phase of its SECuRE clinical trial investigating SAR-bisPSMA (search) Targeted Copper Theranostics in patients with metastatic castrate-resistant prostate cancer (search).
The Phase I/IIa theranostic trial uses 64Cu SAR-bisPSMA (search) for imaging PSMA (search)-expressing lesions and selecting candidates for subsequent 67Cu SAR-bisPSMA (search) therapy.
Preliminary imaging data shows promising tumor targeting and retention with tissue washout, demonstrating superior bone involvement visualization compared to standard bone scans.
Clarity Pharmaceuticals (search) has successfully completed recruitment for the initial dosimetry phase of its SECuRE clinical trial (NCT04868604), investigating SAR-bisPSMA (search) Targeted Copper Theranostics (TCT) in patients with metastatic castrate-resistant prostate cancer (search) (mCRPC (search)). The Australian-based clinical stage radiopharmaceutical company is now preparing dosimetry data for safety review before advancing to the therapeutic phase.
Trial Design and Objectives
The SECuRE trial is a Phase I/IIa theranostic study designed for identification and treatment of prostate specific membrane antigen (search) (PSMA (search))-expressing mCRPC (search) using TCT. The multi-centre, single arm, dose escalation study includes a cohort expansion planned for up to 44 patients in the US. The trial utilizes 64Cu SAR-bisPSMA (search) to visualize PSMA expressing lesions and select candidates for subsequent 67Cu SAR-bisPSMA (search) therapy.
The initial dosimetry phase employed 64Cu SAR-bisPSMA (search) to determine biodistribution and dosimetry of the products in humans. The primary aim of the trial is to determine the safety and efficacy of 67Cu SAR-bisPSMA (search) as a therapy.
Promising Preliminary Results
Dr. Alan Taylor, Clarity's Executive Chairman, reported encouraging preliminary findings from the dosimetry phase. "The PET imaging data acquired in the SECuRE trial to date looks very promising and the images confirm our excellent preclinical results of high tumour targeting and retention whilst seeing washout in other tissues," Taylor stated.
The imaging results demonstrated that 64Cu SAR-bisPSMA (search) can visualize bone involvement, showing advantages over standard bone scans. According to Taylor, this "further supports the emerging evidence of increased sensitivity and specificity of PSMA (search) PET tracers for detecting micrometastatic disease compared to conventional imaging."
Clinical Advantages of Copper-Based Theranostics
Dr. Luke Nordquist, CEO and Urologic Medical Oncologist at the Urology Cancer Center and GU Research Network in Omaha, Nebraska, who treated patients in the initial dosimetry phase, highlighted the clinical benefits of the copper-based approach. "Current standard of care SPECT imaging agents don't have the resolution of the new PET agents, however the new PET agents rely on radionuclides with very short half-lives such as 18F and 68Ga, which limits their availability and utilisation," Nordquist explained.
The longer half-life of 64Cu offers significant logistical advantages. "Having access to centrally manufactured PET imaging products with a more suitable half-life, such as 64Cu, will significantly improve patient care and address the current backlog of patients waiting for critical imaging scans," Nordquist noted.
Theranostic Platform Benefits
Clarity's TCT platform uniquely uses the same chemical entity for both diagnosis and therapy, utilizing the isotope pairing of 64Cu and 67Cu. This approach enables imaging data collection from 1 hour to 72 hours after administration to help determine the suitability of treatment with 67Cu.
Taylor emphasized the manufacturing and logistical advantages: "The central manufacture, logistical and treatment advantages of TCT associated with using the isotope pairing of 64Cu and 67Cu in large patient populations such as prostate cancer (search) will provide significant benefits to both patients and clinicians in comparison to current products in the market."
Market Context and Disease Burden
Prostate cancer (search) represents a significant global health burden, being the second most common cancer diagnosed in men globally and the fifth leading cause of cancer death worldwide. The National Cancer Institute estimated 248,530 new cases of prostate cancer in the US in 2021, with around 34,130 deaths from the disease.
Approximately 34,000 men in the US are diagnosed annually with mCRPC (search), with around 90% having tumors that express PSMA (search). This patient population represents the target demographic for Clarity's SAR-bisPSMA (search) theranostic approach.
Regulatory Landscape
The development occurs within a favorable regulatory environment, with recently updated US National Comprehensive Cancer Network Guidelines now allowing FDA-approved PSMA (search) PET agents to be used as an alternative to conventional imaging. This regulatory shift supports the clinical advancement of PSMA-targeted imaging agents like SAR-bisPSMA (search).
Next Steps
Following the completion of the dosimetry phase, Clarity will progress through safety review before moving to the therapy phase with 67Cu SAR-bisPSMA (search) at all seven clinical sites selected for the trial in the US. The company aims to generate compelling clinical data to advance its ultimate goal of developing better treatments for children and adults with cancer.