Trial of PSMA-PET imaging agent 64Cu-SAR-bisPSMA completes enrollment

Enrollment has been completed for the phase 1 PROPELLER trial exploring the novel PSMA-PET imaging product ⁶⁴Cu-SAR-bisPSMA in patients with treatment-naïve, histologically confirmed prostate cancer who are scheduled for radical prostatectomy.¹

The study has met its target accrual of 30 patients. To enroll in the trial, patients must have at least 1 of these intermediate- to high-risk features: a PSA level ≥10.0 ng/ml within 12 weeks prior to enrolling, a Gleason score of 7 (4+3) or higher, and/or a clinical stage ≥T2b.²

The study aims to assess the safety, tolerability, and efficacy of ⁶⁴Cu-SAR-bisPSMA. Patients will receive imaging with ⁶⁴Cu-SAR-bisPSMA, which will subsequently be sent to blinded central readers who will determine the capability of the agent to detect primary prostate cancer and identify secondary prostate cancer. The study will also assess the image quality across various doses of ⁶⁴Cu-SAR-bisPSMA .

Clarity, the developer of the imaging agent, reported in a news release that it intends to share topline results from the PROPELLER trial in the “coming months” and subsequently proceed with a phase 3 trial.

"The initial imaging data from the PROPELLER trial with the SAR-bisPSMA product looks very encouraging and we look forward to supporting the comprehensive analysis in due course. Having recently also seen the benefits of Clarity's SAR-Bombesin product in breast and prostate cancer patients, there is now growing interest from oncology professionals in Targeted Copper Theranostics (TCTs), particularly due to the efficacy and added flexibility that Clarity's copper-based products provide for patients. Coupled with the logistical benefits TCTs offer through on-demand distribution of ready-to-use products, these may be significant advantages in comparison to the current generation of radiopharmaceuticals. These benefits mean that critical imaging scans can be delivered to cancer patients on time and at a convenient location, representing a treatment paradigm focused on the needs of patients and their treating staff," Louise Emmett, MD, MBChB, BSc, St Vincent's Hospital Sydney, principal investigator of the PROPELLER trial, stated in the news release.

⁶⁴Cu-SAR-bisPSMA is also being explored in the phase 1/2a SECURE trial (NCT04868604),³ which is examining the imaging agent along with the PSMA targeted therapy ⁶⁷Cu-SAR-bisPSMA in patients with metastatic castration-resistant prostate cancer. In the open-label, single-arm, dose-escalation trial, ⁶⁴Cu-SAR-bisPSMA will be used for the selection of appropriate patients who will then receive targeted treatment with ⁶⁷Cu-SAR-bis-PSMA. Recruitment has been completed for the initial dosimetry phase of the trial.

"We are very pleased to have reached full recruitment in our PROPELLER trial. In this trial we are comparing the diagnostic efficacy of ⁶⁴Cu SAR-bisPSMA to the prostate cancer tissue samples (ie, histology), as well as seeing how the images compare to ⁶⁸Ga-PSMA-11, a product that is currently approved in Australia and the United States. We are looking forward to seeing whether the image comparisons in the clinic follow our preclinical observations of higher uptake into tumors with our SAR-bisPSMA product. This is critical in providing a correct diagnosis, especially in patients with early disease. The data from the PROPELLER trial will then inform us on our phase 3 trial protocol and commencement of this next trial in calendar year 2023. We look forward to further progressing our SAR-bisPSMA product to improve treatment outcomes for cancer patients," Dr Alan Taylor, executive chairman of Clarity, commented in the news release.

References

1. Recruitment complete for Clarity's PROPELLER prostate cancer diagnostic trial. Published online July 20, 2022. Accessed July 20, 2022. https://prn.to/3IQWaUS

2. NIH ClinicalTrials.gov. Positron Emission Tomography (PET) Imaging of Participants With Confirmed Prostate Cancer Using 64Cu-SAR-bisPSMA (PROPELLER) (PROPELLER) Last update August 18, 2021. Accessed December 9, 2021. https://clinicaltrials.gov/ct2/show/NCT04839367

3. NIH ClinicalTrials.gov. 64Cu-SAR-bisPSMA and 67Cu-SAR-bisPSMA for Identification and Treatment of PSMA-expressing Metastatic Castrate Resistant Prostate Cancer (SECURE). Last update May 3, 2021. Accessed May 5, 2021. https://clinicaltrials.gov/ct2/show/NCT04868604