FDA Approves Gallium 68 PSMA-11 as PET-Imaging Drug for Prostate Cancer

The FDA has approved Gallium 68 PSMA-11, the first drug for PET imaging of prostate-specific membrane antigen (PSMA)–positive lesions in patients with prostate cancer.

Specifically, the drug is indicated for patients with suspected prostate cancer metastasis who are potentially curable via surgery or radiation therapy. Ga 68 PSMA-11 is also indicated for those with suspected prostate cancer recurrence based on elevated serum prostate-specific antigen levels. The PET imaging drug is a radioactive diagnostic that is given via an intravenous injection.

“Ga 68 PSMA-11 is an important tool that can aid health care providers in assessing prostate cancer,” said Alex Gorovets, MD, acting deputy director of the Office of Specialty Medicine in FDA’s Center for Drug Evaluation and Research, stated in a press release. “With this first approval of a PSMA-targeted PET imaging drug for men with prostate cancer, providers now have a new imaging approach to detect whether or not the cancer has spread to other parts of the body.”

Ga 68 PSMA-11 was developed to bind to PSMA, which is known to be a critical pharmacologic target for imaging in this disease, as cancer cells typically contain higher levels of this antigen. The radioactive agent releases positrons; as such, it can be imaged by PET to identify PSMA-positive lesions in tissue within the body, according to the regulatory agency.

Ga 68 PSMA-11 was investigated in 2 clinical trials that collectively enrolled 960 patients with prostate cancer; these patients were each given 1 injection of the PET imaging agent.

The first trial included a total of 325 patients with prostate cancer, confirmed via biopsy, who had undergone PET/CT or PET/MRI scans with the agent. The participants were eligible for surgical removal of the prostate gland and pelvic lymph nodes; they were also determined to be at increased risk for metastasis.

Of those who continued on to surgery, patients who had positivity in the pelvic lymph nodes on Ga 68 PSMA-11 PET were found to have a clinically important rate of metastatic disease which was confirmed by surgical pathology. "The availability of this information prior to treatment is expected to have important implications for patient care," according to the FDA. For instance, this information could potentially spare patients from undergoing an unnecessary surgical procedure.

The second trial included 635 patients who had rising PSA levels following initial surgery or radiotherapy for their disease, thus demonstrating biochemical evidence of recurrent disease. Here, patients received a single Ga 68 PSMA-11 PET/CT scan or PET/MR scan. These scans revealed that 74% of participants had at least 1 positive lesion in at least 1 body region, whether it was in the bone, prostate bed, pelvic lymph node, or extrapelvic soft tissue.

Moreover, among those who showcased positivity and who had: correlative tissue pathology from biopsies, data from either baseline or follow-up imaging via conventional methods, and serial PSA levels available for evaluation, local recurrence or metastasis was confirmed in about 91% of cases. Investigators concluded that Ga 68 PSMA-11 PET is capable of identifying sites of disease in those with biochemical evidence of recurrent disease; this provides critical information that can potentially inform treatment decisions, according to the regulatory agency.

With regard to safety, no serious reactions were associated with Ga 68 PSMA-11. The most frequently experienced adverse reactions to the PET imaging drug comprised nausea, diarrhea, and dizziness.

Moreover, the FDA warned that there is a risk for misdiagnosis, as Ga 68 PSMA-11 binding can happen in other cancers beyond prostate cancer and other nonmalignant processes could potentially result in errors in image interpretation. Additionally, Ga 68 PSMA-11 is known to contribute to overall long-term cumulative radiation exposure; this has been linked with increased cancer risk.

The approval was granted to the University of California Los Angeles and the University of California San Francisco.

Reference

FDA approves first PSMA-targeted PET imaging drug for men with prostate cancer. News release. FDA. December 1, 2020. Accessed December 1, 2020. https://bit.ly/2Vo5esv.