On May 27, 2021, the FDA accelerated the approval of piflufolastat F-18 (Pylarify; Progenics Pharmaceuticals) injection, the second radioactive, prostate-specific membrane antigen (PSMA)-targeted positron-emission tomography (PET) imaging drug used for the diagnosis of suspected prostate cancer recurrence or metastasis.
Piflufolastat F-18 is indicated for PET diagnosis of PSMA-positive lesions in men with prostate cancer and suspected metastasis who are candidates for initial definitive therapy and for those with suspected prostate cancer recurrence, based on elevated serum prostate-specific antigen (PSA) levels. Last December, the FDA approved the first PSMA-targeted imaging drug, Ga-68 PSMA-11.
“Conventional imaging has significant limitations in detecting prostate cancer, both in initial staging and when the cancer has recurred or spread after initial primary treatment,” said Michael J. Morris, MD, Prostate Cancer Section Head, Genitourinary Medical Oncology, Memorial Sloan Kettering Cancer Center, and lead investigator in the CONDOR clinical trial. He noted that piflufolastat F-18 injection “can detect the spread of disease well before standard imaging and can be a transformative diagnostic tool.”
The FDA approval of piflufolastat F-18 was based on 2 prospective clinical trials that together included 593 men with prostate cancer who received 1 injection of piflufolastat F-18. The first study included 268 patients with prostate cancer who had PET or computed tomography (CT) scans after receiving piflufolastat F-18. The patients were candidates for resection of the prostate gland and pelvic lymph nodes and were at higher risk for metastasis. Among those who proceeded to surgery, metastatic cancer was confirmed by surgical pathology in the patients who had positive lesions on the piflufolastat F-18 PET scan. Having this information before surgery may spare patients from undergoing needless procedures.
The second study included 208 patients with elevated serum PSA levels after initial prostate surgery or other definitive therapy that provided evidence of recurrent prostate cancer. Before undergoing the piflufolastat F-18–based PET or CT scan, the patients had baseline conventional imaging that did not show definite metastasis. The use of piflufolastat F-18 detected at least 1 positive lesion in at least 1 body region (bone, prostate bed, pelvic lymph node, other lymph nodes, or soft tissue) in 60% of the patients.
The diagnosis of prostate cancer recurrence or metastasis was confirmed in an estimated 85% to 87% of patients (depending on the reader) with positive lesions using piflufolastat F-18–based PET scan who had correlated tissue pathology from biopsies, baseline or follow-up imaging by conventional methods, or serial PSA levels.
The most common adverse events with piflufolastat F-18 were headache, altered taste, and fatigue.