Trial of PSMA-PET imaging agent 64Cu-SAR-bisPSMA meets primary end points

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 has met its primary end points.¹

The secondary end point of optimal dose for subsequent investigation was also achieved at a dose of 200 MBq.

Clarity Pharmaceuticals, the developer of the imaging agent, announced in a press release that ⁶⁴Cu-SAR-bisPSMA was, “safe, well tolerated, and efficacious in detecting primary prostate cancer.” The secondary end point of optimal dose for subsequent investigation was also achieved at a dose of 200 MBq.

Specific data from the trial will first be shared next year at the 2023 ASCO Genitourinary Cancers Symposium in February, according to Clarity. The company now plans to use the PROPELLER outcomes to inform the development of a pivotal phase 3 trial scheduled to launch next year.

“We are impressed by the high uptake of ⁶⁴Cu SAR-bisPSMA and look forward to progressing its development and further analyzing the data. We have seen to date the high uptake of the product in tumors and the ability to image ⁶⁴Cu SAR-bisPSMA at later time points, which may improve the treatment paradigm for many men with prostate cancer. Being able to accurately stage cancer means that we can better develop a treatment approach that can more effectively prevent its further spread throughout the body. We are excited to continue analysing the data and present the initial results at the ASCO GU Symposium in February 2023,” Louise Emmett, MD, MBChB, BSc, St Vincent's Hospital Sydney, principal investigator of the PROPELLER trial, stated in the news release.

Overall, the PROPELLER trial aimed to assess the safety, tolerability, and efficacy of ⁶⁴Cu-SAR-bisPSMA. Patients received imaging with ⁶⁴Cu-SAR-bisPSMA, which was subsequently sent to blinded central readers who determined the capability of the agent to detect primary prostate cancer and identify secondary prostate cancer. The study also assessed the image quality across various doses of ⁶⁴Cu-SAR-bisPSMA .

The study accrued 30 patients, which was the targeted enrollment goal.² 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.³

“The initial PROPELLER data further substantiates the utility of ⁶⁴Cu SAR-bisPSMA in the diagnosis of prostate cancer. Combined with our clinical and pre-clinical trial data to date, this validates SAR-bisPSMA as a potential best-in-class PSMA agent for the diagnosis (with ⁶⁴Cu) and subsequent treatment (with ⁶⁷Cu) of prostate cancer. As such, we are thrilled to continue the development of SAR-bisPSMA as a theranostic pair in our SECuRE trial2 as well as in two diagnostic prostate cancer indications: pre-prostatectomy/pre-definitive treatment and suspected biochemical recurrence of the disease (COBRA trial3). We have already commenced work towards our diagnostic Phase III trials with ⁶⁴Cu SAR-bisPSMA and we look forward to engaging with the United States Food and Drug Administration shortly as we get closer to our ultimate goal of improving treatment outcomes of people with cancer,” Dr Alan Taylor, executive chairman of Clarity, commented in the news release.

References

1. Positive topline results from Clarity’s PROPELLER SAR-bisPSMA prostate cancer diagnostic trial. Published online December 14, 2022. Accessed December 15, 2022. https://www.claritypharmaceuticals.com/news/propeller_topline.

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

3. 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