FDA fast tracks 64Cu-SAR-bisPSMA for biochemically recurrent prostate cancer

The FDA has awarded a fast track designation (FTD) to ⁶⁴Cu-SAR-bisPSMA for PET imaging of prostate-specific membrane antigen (PSMA)-positive lesions in patients with biochemical recurrence (BCR) of prostate cancer following initial definitive therapy, Clarity Pharmaceuticals announced in a news release.¹

The FTD was primarily supported by data from the phase 1/2 COBRA trial.

FTD is awarded to novel agents that are intended to treat or prevent serious conditions and have the potential to address an unmet medical need. With this designation, the development process for ⁶⁴Cu-SAR-bisPSMA can benefit from more frequent engagement with the FDA, eligibility for accelerated approval, and priority review.

⁶⁴Cu-SAR-bisPSMA was previously granted a fast track designation in August 2024 for PET imaging of PSMA-positive prostate cancer lesions in patients with suspected metastasis who are candidates for initial definitive therapy.

“Receiving the second FTD for ⁶⁴Cu-SAR-bisPSMA and well within the 60-day period following our application submission, reserved by the US FDA for review, is yet another significant milestone in our bisPSMA program,” said Clarity’s Executive Chairperson, Alan Taylor, PhD, in the news release.¹ “This highlights the high unmet need for novel diagnostics in prostate cancer and the high quality of data we presented to the FDA.”

Data on ⁶⁴Cu-SAR-bisPSMA

The FTD was primarily supported by data from the phase 1/2 COBRA trial (NCT05249127), which demonstrated the safety and efficacy of the agent in detecting prostate cancer lesions in patients with BCR who had negative or equivocal standard of care scans at study entry.^2,3 In total, the trial enrolled 52 patients, of whom 42 were included in the efficacy analysis.

Overall, data showed that ⁶⁴Cu-SAR-bisPSMA was able to identify lesions in approximately 60% of patients on same-day imaging and up to 80% of patients on next-day imaging in whom standard of care imaging was unable to detect any lesions.

Further, the correct detection rate (defined as the proportion of true positive patients who had at least 1 evaluable reference standard data point among all participants) ranged from 21.4% to 28.6% among 3 central readers on day 0 and 28.6% to 38.1% on day 1. The region-level positive predictive value (defined at the proportion of true positive regions ⁶⁴Cu-SAR-bisPSMA PET/CT scan with corresponding evaluable reference standard among all positive regions) ranged from 39.1% to 44.8% on day 0 and 32.7% to 43.3% on day 1 across all readers.

Investigators in the trial noted that ⁶⁴Cu-SAR-bisPSMA imaging led to a change of treatment plan in 48% of patients.

According to Clarity, findings from this study informed planning for the ongoing phase 3 AMPLIFY trial.

The company announced plans to launch the phase 3 AMPLIFY trial in October 2024.⁴ Overall, the non-randomized, single-arm, open-label, multicenter trial will further evaluate the ability of ⁶⁴Cu-SAR-bisPSMA PET/CT to detect biochemical recurrence of prostate cancer. Efficacy will be assessed on both same-day imaging (day 1, day of administration) and next-day imaging (day 2, approximately 24 hours post-administration).

The study plans to enroll approximately 220 patients who have rising or detectable prostate-specific antigen (PSA) levels following initial definitive treatment for prostate cancer. According to the company, recruitment for the trial is expected to commence in the coming months.

Clarity Pharmaceuticals noted in the news release, “As a pivotal trial, the final study results are intended to provide sufficient evidence to support an application to the FDA for approval of ⁶⁴Cu-SAR-bisPSMA as a new diagnostic imaging agent in prostate cancer in patients with BCR.”¹

References

1. Clarity receives U.S. FDA Fast Track Designation for Cu-64 SAR-bisPSMA in biochemical recurrence of prostate cancer. News release. Published online and accessed January 24, 2025. https://www.claritypharmaceuticals.com/news/ftd-2/

2. Initial COBRA results: Clarity’s SAR-bisPSMA is safe and highly effective in detecting tumours in prostate cancer patients. Phase 3 planning underway. News release. Clarity Pharmaceuticals. February 15, 2024. Accessed January 24, 2025. https://www.claritypharmaceuticals.com/news/cobra_results/

3. Nordquist L, Lengyelova E, Saltzstein D, et al. COBRA: Assessment of safety and efficacy of 64Cu-SAR-bisPSMA in patients with biochemical recurrence of prostate cancer following definitive therapy. Presented at: 2024 American Society of Clinical Oncology Annual Meeting. Chicago, Illinois. May 31-June 4, 2024. Abstract 5100. https://ascopubs.org/doi/10.1200/JCO.2024.42.16_suppl.5100

4. Positive guidance from the U.S. FDA on 64Cu-SAR-bisPSMA phase III trial in patients with recurrence of prostate cancer. News release. Clarity Pharmaceuticals. October 14, 2024. Accessed January 24, 2025. https://www.prnewswire.com/news-releases/positive-guidance-from-the-us-fda-on-64cu-sar-bispsma-phase-iii-trial-in-patients-with-recurrence-of-prostate-cancer-302274687.html