64Cu-SAR-bisPSMA Earns FDA Fast Track Designation for PET Imaging in Prostate Cancer

The FDA has granted fast track designation to ⁶⁴Cu-SAR-bisPSMA for use in the positron emission tomography (PET) imaging of patients with prostate-specific membrane antigen (PSMA)–positive prostate cancer lesions with suspected metastasis who are candidates for initial definitive therapy.¹

⁶⁴Cu-SAR-bisPSMA features two PSMA-targeting agents connected via Clarity’s proprietary sarcophagine (SAR) technology, which is designed to hold copper isotopes in a cage-like structure called a chelator. The SAR technology is intended to prevent copper leakage into the body, and the SAR-bisPSMA can be used with the copper-64 isotope for imaging and the copper-67 isotope for therapy.

Findings from the phase 1 PROPELLER trial (NCT048393671) showed that ⁶⁴Cu-SAR-bisPSMA was safe and well tolerated in patients with confirmed prostate cancer prior to undergoing radical prostatectomy and lymph node dissection. One patient from the evaluable population (n = 30) experienced grade 1 dysgeusia. Additionally, the imaging agent generated higher maximum standardized uptake values compared with ⁶⁸Ga PSMA-11 in patients given ⁶⁴Cu-SAR-bisPSMA at 200 MBq (n = 18). Results from reader 1 showed that primary prostate cancer was detected in 100% of patients given ⁶⁴Cu-SAR-bisPSMA vs 77.8% of those given ⁶⁸Ga PSMA-11. Results from reader 2 demonstrated primary prostate cancer was detected in 85.7% of patients given ⁶⁴Cu-SAR-bisPSMA vs 83.3% of those given 68Ga PSMA-11.²

The ongoing phase 3 CLARIFY trial (NCT06056830) is further assessing 64Cu-SAR-bisPSMA in patients with high-risk prostate cancer prior to radical prostatectomy.¹

Furthermore, data from the phase 1/2 COBRA trial (NCT05249127) showed that ⁶⁴Cu-SAR-bisPSMA was safe and effective in detecting prostate cancer lesions in patients with biochemical recurrence, and another registrational phase 3 study is being planned for this population.

“Receiving fast track designation for ⁶⁴Cu-SAR-bisPSMA is a significant milestone, especially as we are actively recruiting into our first registrational phase 3 trial, CLARIFY, and preparing for an end-of-phase meeting with the FDA for a second pivotal phase 3 trial with this product,” Alan Taylor, PhD, executive chairperson of Clarity Pharmaceuticals, stated in a news release.¹ “The designation will allow us to work closely with the FDA to facilitate the development process, potentially accelerating the approval of this best-in-class diagnostic.”

The ongoing CLARIFY trial is enrolling patients at least 18 years of age with previously untreated, histologically confirmed adenocarcinoma of the prostate.³ Patients must have high-risk disease or greater per the National Comprehensive Cancer Network Guidelines, defined as a clinical stage of at least T3a, a grade group of at least 4, or a PSA level higher than 20 ng/mL. To be included, patients must elect to undergo radical prostatectomy with pelvic lymph node dissection.

Key exclusion criteria consist of the administration of any high-energy gamma-emitting radioisotope higher than 300 KeV within 5 half-lives of day 1 of the study, known or expected hypersensitivity to ⁶⁴Cu-SAR-bisPSMA, and predominant small cell or neuroendocrine prostate cancer.

All patients in the single-arm, open-label study are receiving 200 MBq of ⁶⁴Cu-SAR-bisPSMA as a single administration.

The study’s primary end point is the diagnostic performance of PET imaging using ⁶⁴Cu-SAR-bisPSMA in detecting regional nodal metastases. Secondary end points include safety and tolerability; consistency of ⁶⁴Cu-SAR-bisPSMA imaging using 3 central readers; positive and negative predicted values of ⁶⁴Cu-SAR-bisPSMA imaging to detect prostate cancer within pelvic lymph nodes compared with standard of truth; the sensitivity of ⁶⁴Cu-SAR-bisPSMA imaging to detect prostate cancer within the prostate gland compared with standard of truth; and the diagnostic ability of ⁶⁴Cu-SAR-bisPSMA imaging to detect regional nodal metastases without subregion matching.

“We believe that ⁶⁴Cu-SAR-bisPSMA could be a game changer in prostate cancer diagnosis. Due to its dual targeting structure, bisPSMA, and the longer half-life of copper-64, enabling next-day imaging, this unique product has shown higher tumor uptake and retention and exhibited a capability of detecting much smaller lesions,” Taylor added in a news release.¹ “The longer half-life of the isotope also translates into a longer shelf life than currently used diagnostic radiopharmaceuticals, allowing for centralized manufacture and wider distribution, while also supporting flexible patient scheduling.”

References

1. Clarity receives FDA fast track designation for ⁶⁴Cu-SAR-bisPSMA. News release. Clarity Pharmaceuticals. August 22, 2024. Accessed August 26, 2024. https://www.claritypharmaceuticals.com/news/fast-track/
2. PROPELLER trial results – SAR-bisPSMA safe, well tolerated and efficacious in the detection of prostate cancer. News release. February 14, 2023. Accessed August 26, 2024. https://www.claritypharmaceuticals.com/news/propeller_results/
3. Positron emission tomography using ⁶⁴Cu-SAR-bisPSMA in participants with high-risk prostate cancer prior to radical prostatectomy (CLARIFY). ClinicalTrials.gov. Updated August 23, 2024. Accessed August 26, 2024. https://clinicaltrials.gov/study/NCT06056830