On May 27, the U.S. Food and Drug Administration (FDA) approved piflufolastat F-18 injection (Pylarify), an F-18–labeled prostate-specific membrane antigen (PSMA)-targeted positron-emission tomography (PET) imaging agent, to identify suspected metastasis or recurrence of prostate cancer. This is the first and only commercially available approved PSMA PET imaging agent for prostate cancer. The product will be immediately available in parts of the mid-Atlantic and southern regions, and availability is expected to rapidly expand over the next 6 months with broad availability across the United States anticipated by year-end.
Identification of suspected metastatic prostate cancer in men considering initial definitive therapy is important to optimize treatment planning and to avoid futile interventions. Of men with localized prostate cancer who undergo initial curative intent/management, up to 50% may experience recurrence of their disease within 10 years of treatment. Recurrent disease is often detected by a rise in serum prostate-specific antigen (PSA) levels; however, conventional imaging, especially at low PSA levels, may not be able to identify the location and extent of the disease in the majority of cases.
Piflufolastat F-18 injection was developed to target PSMA, a protein that is overexpressed on the surface of more than 90% of primary and metastatic prostate cancer cells. It binds to the target, enabling the reader of the PET scan to detect and locate the disease. Cyclotron production of F-18 offers high-batch capacity and high-image resolution, and F-18’s 110-minute half-life allows for wide geographic distribution.
OSPREY and CONDOR Studies
The approval of piflufolastat F-18 injection is based on data from two studies—OSPREY and CONDOR—designed to establish the safety and diagnostic performance of the agent across the prostate cancer disease continuum. Results from OSPREY (cohort A) demonstrated improvement in specificity and positive predictive value (PPV) of piflufolastat F-18 injection PET imaging over conventional imaging in men at risk for metastatic prostate cancer prior to initial therapy. CONDOR studied men with biochemical-recurrent prostate cancer. In patients with biochemical-recurrent prostate cancer and noninformative baseline imaging, piflufolastat F-18 injection demonstrated high correct localization and detection rates, including in patients with low PSA values (median = PSA 0.8 ng/mL).
In the clinical trials, piflufolastat F-18 injection was well tolerated. In OSPREY and CONDOR, 593 patients with various states of prostate cancer were exposed to a single dose. Adverse reactions (headache, dysgeusia, and fatigue) were reported in ≤ 2% of patients within the studies. In addition, a delayed hypersensitivity reaction was reported in one patient (0.2%) with a history of allergic reaction.
“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. Specifically, standard imaging poorly detects the early spread to distant organs, such as the lymph nodes, bones, and other organs,” said Michael J. Morris, MD, Prostate Cancer Section Head, Genitourinary Medical Oncology, Memorial Sloan Kettering Cancer Center and the lead study investigator in the CONDOR trial/study investigator in the OSPREY trial. “[Piflufolastat F-18 injection] can detect the spread of disease well before standard imaging and can be a transformative diagnostic tool that helps clinicians develop treatment plans based on a much more accurate understanding of a patient’s distribution of disease.”
More About the Agent and Dosing
Piflufolastat F-18 injection is a fluorinated small-molecule PSMA-targeted PET imaging agent that enables visualization of lymph nodes and bone and soft tissue metastases to determine the presence or absence of recurrent and/or metastatic prostate cancer.
The recommended piflufolastat F-18 injection dose is 333 MBq (9 mCi), with an acceptable range of 296 MBq to 370 MBq (8 mCi to 10 mCi), administered as a bolus intravenous injection.
