FDA Issues Breakthrough Therapy Designation for Emerging PSMA PET Agent in Men with Suspected PCa Recurrence

The Food and Drug Administration (FDA) has granted a breakthrough therapy designation for ⁶⁴Cu-SAR-bisPSMA, a PSMA PET radiopharmaceutical, in men with suspected recurrence of prostate cancer (PCa) based on elevated prostate-specific antigen (PSA) levels.

Recent research has demonstrated significant utility for the use of ⁶⁴Cu-SAR-bisPSMA in patients with biochemical recurrence (BCR) of PCa.

In the phase II Co-PSMA trial, researchers compared ⁶⁴Cu-SAR-bisPSMA (Clarity Pharmaceuticals) and ⁶⁸Ga-PSMA-11 in 50 patients who had BCR of PCa after a radical prostatectomy. After initial evaluation with ⁶⁸Ga-PSMA-11, the study authors found that next-day imaging with 64Cu-SAR-bisPSMA more than doubled the number of positive PET scans (78 percent vs. 36 percent) and number of detected PCa lesions (63 vs. 24). The use of ⁶⁴Cu-SAR-bisPSMA also led to treatment changes in 44 percent of the cohort, according to the study.

In an episode of the Molecular Imaging in Focus series, Louise Emmett, MBChB, FRACP, FAANMS, MD, the primary investigator for the Co-PSMA trial, said the increased binding and longer half-life (12 hours) for ⁶⁴Cu-SAR-bisPSMA are key attributes in this patient population.

“It's the double whammy, I think, of the bifid structure and the long half-life of the PET agent, which gives more time for it to concentrate in the cancer and then wash out of all the other structures. That makes it really nice, particularly in this biochemical recurrence setting,” noted Dr. Emmett, the director of theranostics and nuclear medicine at St. Vincent’s Hospital Sydney in Sydney, Australia.

“The FDA’s award of the first Breakthrough Therapy designation in the history of PSMA PET imaging highlights both the unmet need for more accurate detection of recurrent prostate cancer lesions and the significance of the data generated to date, which indicates improved diagnostic performance of ⁶⁴Cu-SAR-bisPSMA compared to SOC (standard of care) PSMA PET in patients with BCR of prostate cancer,” added Alan Taylor, the executive chairperson of Clarity Pharmaceuticals.

⁶⁴Cu-SAR-bisPSMA previously garnered two FDA fast track designations for PCa BCR in patients who have had definitive treatment and suspected metastasis in men who are candidates for definitive PCa treatment.