On May 27, 2021, the U.S. Food and Drug Administration (FDA) approved piflufolastat F 18 (Pylarify®), a drug for positron-emission tomography (PET) imaging of prostate-specific membrane antigen (PSMA)-positive lesions in patients with prostate cancer.
FDA approved the first PSMA-targeted PET imaging drug, Ga 68 PSMA-11, on December 1, 2020, for the same prostate cancer imaging indications as piflufolastat F 18. Ga 68 PSMA-11 is currently available only at two sites in California. Piflufolastat F 18 is anticipated to be distributed from multiple sites throughout the United States.
Piflufolastat F 18 is a radioactive diagnostic agent administered via IV injection. With approval, certain patients with prostate cancer will have greater access to PSMA-targeted PET imaging that can aid healthcare providers in assessing prostate cancer.
Safety and efficacy were evaluated in 593 patients with prostate cancer who each received one injection of piflufolastat F 18 in two prospective clinical trials. In the first trial, a cohort of 268 patients with biopsy-proven prostate cancer underwent PET/computed tomography (CT) scans performed with piflufolastat F 18. The patients were candidates for surgical removal of the prostate gland and pelvic lymph nodes and were considered at higher risk for metastasis. Patients who proceeded to surgery after positive readings in the pelvic lymph nodes on piflufolastat F 18 PET had a clinically important rate of metastatic cancer confirmed by surgical pathology.
The second trial enrolled 208 patients with rising serum prostate-specific antigen (PSA) levels after initial prostate surgery or other definitive therapy, which is considered biochemical evidence of recurrent prostate cancer. Baseline conventional imaging did not show definite spread of prostate cancer, but piflufolastat F 18 PET detected at least one positive lesion in at least one body region (bone, prostate bed, pelvic lymph node, other lymph nodes, or soft tissue) in 60% of the patients.
In patients with positive piflufolastat F 18 PET readings who had correlative tissue pathology from biopsies, results from baseline or follow-up imaging by conventional methods, or serial PSA levels available for comparison, local recurrence or metastasis of prostate cancer was confirmed in an estimated 85%–87%, depending on the reader. Both trials demonstrated that piflufolastat F 18 PET provides clinical guidance on a patient’s potential for metastatic disease that can help patients and providers make appropriate treatment decisions.
The most common adverse reactions were headache, altered taste, and fatigue. Piflufolastat F 18 increases a patient’s risk for hypersensitivity reactions, particularly in patients with a history of allergy to other drugs and foods. Patients are also at risk for misdiagnosis because piflufolastat F 18 binding may occur in other types of cancer as well as certain nonmalignant conditions, which may lead to image interpretation errors. Piflufolastat F 18 contributes to a patient’s overall long-term cumulative radiation exposure, which is associated with an increased risk for cancer.
Piflufolastat F 18 received priority review designation for the approval. A description of FDA expedited programs is in the Guidance for Industry—Expedited Programs for Serious Conditions—Drugs and Biologics.
Healthcare professionals should report all serious adverse events they suspect are associated with the use of any medicine or device to FDA’s MedWatch Reporting System or by calling 800-FDA-1088.