FDA Approves Radiohybrid PET Diagnostic Agent Posluma for PSMA-Positive Lesions in Prostate Cancer

The PET diagnostic imaging agent, flotufolastat F 18 injection (Posluma; formerly 18F-rhPSMA-7.3) has been approved by the FDA for the identification of prostate-specific membrane antigen (PSMA)–positive lesions in men with prostate cancer. To be eligible for imaging with the agent, patients must have suspected metastasis and be eligible for initial definitive therapy or have suspected recurrence based on elevated serum prostate-specific antigen (PSA) level. The approval is based on data from the phase 3 LIGHTHOUSE (NCT04186819) and SPOTLIGHT (NCT04186845) studies.1

In LIGHTHOUSE, Posluma demonstrated high specificity for 296 patients with unfavorable, intermediate-risk or high-/very high–risk prostate cancer across results from 3 central, blinded readers. The specificity was 93% (95% CI, 89%-96%), 94% (95% CI, 90%-97%), and 97% (95% CI, 94%-99%).2

Of note, the agent has the following safety warnings including image interpretations that may demonstrate false positive results. The label states that flotufolastat F 18 is not specific for prostate cancer and may occur in normal tissue, therefore it is recommended that clinical correlation via histopathological evaluation occur.2

Safety of the agent was evaluated in 747 patients with prostate cancer, among whom adverse reactions were minimal with diarrhea reported in 5 patients (0.7%), blood pressure increase in 4 patients (0.5%), and injection site pain in 3 patients (0.4%).2

For administration of the agent, the recommended amount of radioactivity is 296 MBq (8 mCi) via intravenous bolus injection. Imaging should occur approximately 60 minutes after administration with scanning starting from mid-thigh toward the base of the skull.2

It is recommended that waterproof gloves, effective radiation shielding (ie, syringe shields) should be used when handling the Posluma.2

“Effective staging in newly diagnosed prostate cancer—determining its presence and helping determine whether it may have metastasized—is critical in establishing optimal clinical management strategies, because up to 25% of patients with primary prostate cancer may have detectable regional pelvic lymph node metastases, which are correlated with a risk for recurrence and associated overall survival,” Brian F. Chapin, MD, associate professor, Department of Urology, Division of Surgery at The University of Texas MD Anderson Cancer Center in Houston said in a news release.1 “Conventional imaging techniques such as CT and MRI are limited in the information they may provide. The LIGHTHOUSE study looked at unfavorable intermediate, high- and very high–risk patients who were scheduled for radical prostatectomy plus pelvic lymph node dissection prior to POSLUMA PET. The study showed that POSLUMA PET provided clinically valuable information prior to surgery that would likely result in management changes for these patients.”

“The highly variable nature of recurrent prostate cancer presents clinical challenges, and up to 40% of patients who undergo radical prostatectomy, and up to 50% of patients who undergo radiation therapy will develop local or distant recurrences within 10 years,” David M. Schuster, MD, FACR, professor of radiology and imaging sciences at Emory University School of Medicine, and researcher at Winship Cancer Institute of Emory University stated in a news release.1 “The ability to determine the extent and location of recurrent disease is necessary to inform physicians and their patients for appropriate clinical management. The Phase 3 SPOTLIGHT study investigated the diagnostic performance of POSLUMA PET imaging as a potential decision-making aid in assessing suspected biochemical recurrence of the disease and demonstrated that it offered precision diagnostic performance even at low PSA levels with an overall 83% detection rate.”

According to a news release from the developer Blue Earth Diagnostics, the imaging agent will be commercially available in early June 2023.1


  1. US FDA approves Blue Earth Diagnostics’ Posluma (flotufolastat F 18 injection, first radiohybrid PSMA-targeted PET imaging agent for prostate cancer. News release. Blue Earth Diagnostics. May 30, 2023. Accessed May 30, 2023. https://bit.ly/42aFlMJ
  2. Posluma. Prescribing information. Blue Earth Diagnostics; 2023. Accessed May 30, 2023. https://www.posluma.com/prescribing-information.pdf

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