First drug to help detect prostate-specific membrane antigen positive lesions

WASHINGTON — The FDA approved Gallium (Ga) 68 PSMA-11, the first drug designed to assist health care providers in identifying prostate-specific membrane antigen (PSMA) positive lesions during positron emission tomography (PET) imaging of the prostate.

In its announcement, the agency noted that Ga 68 PSMA-11, a radioactive diagnostic agent administered via intravenous injection, is indicated for patients with “suspected prostate cancer metastasis… who are potentially curable by surgery or radiation therapy,” as well as “patients with suspected prostate cancer recurrence based on elevated serum prostate-specific antigen (PSA) levels.”

“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, in a statement. “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 works by binding to PSMA, which can then be imaged by PET to help physicians detect PSMA-positive prostate cancer throughout the body, the FDA explained.

The approval was based on results from two prospective clinical trials evaluating Ga 68 PSMA-11 in a total of 960 men with prostate cancer who each received one injection of the drug. “In the first trial, 325 patients with biopsy-proven prostate cancer underwent PET/CT or PET/MRI scans performed with Ga 68 PSMA-11,” the FDA wrote. “These patients were candidates for surgical removal of the prostate gland and pelvic lymph nodes and were considered at higher risk for metastasis. Among the patients who proceeded to surgery, those with positive readings in the pelvic lymph nodes on Ga 68 PSMA-11 PET had a clinically important rate of metastatic cancer confirmed by surgical pathology. The availability of this information prior to treatment is expected to have important implications for patient care. For example, it may spare certain patients from undergoing unnecessary surgery.

“The second trial enrolled 635 patients who had rising serum PSA levels after initial prostate surgery or radiotherapy, and thus had biochemical evidence of recurrent prostate cancer,” the agency continued. “All of these patients received a single Ga 68 PSMA-11 PET/CT scan or PET/MR scan. Based on the scans, 74% of these patients had at least one positive lesion detected by Ga 68 PSMA-11 PET in at least one body region (bone, prostate bed, pelvic lymph node, or extra-pelvic soft tissue). In patients with positive Ga 68 PSMA-11 PET readings who had correlative tissue pathology from biopsies, results from baseline or follow-up imaging by conventional methods, and serial PSA levels available for comparison, local recurrence or metastasis of prostate cancer was confirmed in an estimated 91% of cases. Thus, the second trial demonstrated that Ga 68 PSMA-11 PET can detect sites of disease in patients with biochemical evidence of recurrent prostate cancer, thereby providing important information that may impact the approach to therapy.”

No serious adverse reactions were attributed to the drug in either trial—the most common adverse events included nausea, diarrhea, and dizziness. However, “there is a risk for misdiagnosis because Ga 68 PSMA-11 binding may occur in other types of cancer as well as certain non-malignant processes which may lead to image interpretation errors,” the agency noted. “There are radiation risks because Ga 68 PSMA-11 contributes to a patient’s overall long-term cumulative radiation exposure, which is associated with an increased risk for cancer.”

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

John McKenna, Associate Editor, BreakingMED™

Cat ID: 25

Topic ID: 78,25,730,25,192,725,925