PSMA-Targeted Imaging Agent Posluma Approved to Aid in Prostate Cancer Detection

The Food and Drug Administration (FDA) has approved Posluma^® (flotufolastat F 18) injection for positron emission tomography (PET) of prostate-specific membrane antigen (PSMA) positive lesions in men with prostate cancer, with suspected metastasis who are candidates for initial definitive therapy; or with suspected recurrence based on elevated serum prostate-specific antigen (PSA) level.

Posluma consists of a radiohybrid PSMA-targeted receptor ligand that binds to and is internalized by prostate cancer cells. The product assists clinicians in detecting and localizing prostate cancer as fluorine-18 is a ß+ emitting radionuclide that can be detected using PET.

The approval of Posluma was based on data from the LIGHTHOUSE study (ClinicalTrials.gov Identifier: NCT04186819), a phase 3, prospective, open-label, single-arm trial that included patients with prostate cancer who were candidates for initial definitive therapy. All study participants received a single dose of Posluma. Three central readers blinded to clinical information interpreted the scans for lesions considered positive for prostate cancer in pelvic lymph nodes.

The study demonstrated high specificity for the detection of pelvic lymph nodes (overall specificity of 96%) as compared with histopathology standard of truth in men with PSMA-positive lesions prior to radical prostatectomy. The overall sensitivity of Posluma was reported to be 24% by majority read.

“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,” said Brian F. Chapin, MD, Associate Professor, Department of Urology, Division of Surgery, The University of Texas MD Anderson Cancer Center, and Coordinating Investigator of the phase 3 LIGHTHOUSE study. “The study showed that Posluma PET provided clinically valuable information prior to surgery that would likely result in management changes for these patients.”

Posluma was also investigated in the SPOTLIGHT study (ClinicalTrials.gov Identifier: NCT04186845), which included patients with biochemical evidence of recurrent prostate cancer. All patients received a single dose of Posluma. Three central readers blinded to clinical information interpreted each scan for the presence and location of lesions considered positive for prostate cancer.

Results showed an overall detection rate of 83% (322/389) based on the majority read from the 3 blinded PET readers.  Among patients with prior prostatectomy, the detection rates were: 64% (77/121) for PSA level less than 0.5ng/mL; 76% (51/67) for PSA level 0.5 to less than 1ng/mL; 93% (42/44) for PSA 1 to less than 2ng/mL; and 97% (152/156) for PSA level greater than or equal 2ng/mL.

The most common adverse reactions reported with Posluma were diarrhea, increased blood pressure, and injection site pain.

Posluma is expected to be commercially available in early June 2023.