Flotufolastat F 18 Shows Role of PET Imaging in Prostate Cancer

prostate cancer under the microscope: © heitipaves - stock.adobe.com

Flotufolastat F 18 (Posluma) helps guide treatment selection for positron emission tomography (PET) in men with newly diagnosed, high-risk prostate cancer who had negative results with conventional imaging, according to results from a sub-group analysis from the phase 3 LIGHTHOUSE trial (NC04186819).¹

Findings presented at ASTRO 2023 showed that in 174 patients who underwent surgery, the sensitivity and specificity of flotufolastat F 18 for the detection of pelvic lymph nodes ranged from 24-33% and 92-96%, respectively. These data were from across 3 blinded, independent readers.

For flotufolastat F 18 in 197 patients, the detection rate for M1 lesions was 14%-25% across the 3 readers, and of the identified lesions, 16-25 were successfully verified as true positive. These data demonstrated a M1 verified detection rate of 8.1-13%, across the 3 readers.

“Effective initial staging of prostate cancer, particularly with regards to the detection of metastatic disease, is critical to optimal clinical management of patients,” said Phillip H. Kuo, MD, PhD, departments of medical imaging, medicine, and biomedical engineering at the University of Arizona, in a press release.¹

“The demonstrated performance of PSMA-PET imaging fits an important unmet need, given that conventional imaging techniques are limited in the information they provide. This analysis from the LIGHTHOUSE study showed that flotufolastat F 18 provides clinically useful information about the presence of both metastatic pelvic lymph nodes and M1 disease prior to surgery in patients with high-risk prostate cancer who had negative results on conventional imaging. Such information can help guide treatment selection and potentially avoid futile surgery for patients with high-risk disease,” Kuo added._¹

In May 2023, the FDA approved flotufolastat F 18, indicated for 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. This approval was based on findings from the phase 3 LIGHTHOUSE and SPOTLIGHT (NCT04186845) trials.^2,3

The multicenter, single-arm, LIGHTHOUSE trial assessed the imaging agent in 335 newly diagnosed patients with prostate cancer who had unfavorable intermediate- to very high-risk prostate cancer. Patients must also have been set to undergo radical prostatectomy and pelvic lymph node dissection. Once enrolled, PET/CT was performed for 50 to 70 minutes on patients, following a 296 MBq (8mCi) intravenous dose of 18F-rHPSMA-7.3.²

In this analysis of LIGHTHOUSE, a subgroup of patients with high/very high-risk prostate cancer were evaluated. Patients included those with no evidence of nodal or metastatic disease on conventional imaging, and those who were treatment-naïve scheduled for radical prostatectomy (RP) plus pelvic lymph node (PLN) dissection underwent flotufolastat F 18 PET.¹

Before RP, local readers interpreted the scans. This was prior to the blinded read by 3 central readers. If M1 disease was indicated in the local read, verification of PET-positive M1 lesions was attempted before treatment. This included biopsy, surgery, or confirmatory follow-up imaging.

In the analysis, the sensitivity and specificity of flotufolastat F 18 was evaluated for detection of PLN metastases in high or very high-risk patients who had negative conventional imaging at baseline, who had undergone flotufolastat F 18 PET, and subsequent surgery.

There were no serious adverse events (AEs) seen and overall, 28 of the 356 (7.9%) patients given flotufolastat F 18 had at least 1 treatment-emergent AEs which was potentially related to flotufolastat F 18. Among those in the LIGHTHOUSE trial, the most frequently reported AE was injection site pain, which was observed in 0.8% (n = 3) of patients.

“[Flotufolastat F 18] provides physicians with high-quality diagnostic information based on its diagnostic performance even at low PSA levels, high-affinity PSMA binding and low urinary bladder activity. In a post-hoc phase 3 analysis, as well as in preclinical and phase 1 studies, [flotufolastat F 18] demonstrated low urinary bladder activity, providing for enhanced image evaluation in the prostate and regions near the ureters for patients with prostate cancer,” added David E. Gauden, PhD, chief executive officer of Blue Earth Diagnostics, in a press release.¹

REFERENCES:

Additional results of POSLUMA® (Flotufolastat F 18) performance in newly diagnosed, high-risk prostate cancer patients presented at ASTRO. News release. Blue Earth Diagnostics. October 3, 2023. Accessed October 4, 2023. https://tinyurl.com/2s484xxn

Blue Earth Diagnostics announces additional results from phase 3 LIGHTHOUSE trial of investigational PET imaging agent 18F-rhPSMA-7.3 in newly diagnosed prostate cancer. News release. Blue Earth Diagnostics. February 16, 2023. Accessed May 30, 2023. https://tinyurl.com/3dhxwb58

Schuster DM. Detection rate of 18F-rhPSMA-7.3 PET in patients with suspected prostate cancer recurrence: results from a phase 3, prospective, multicenter study (SPOTLIGHT). J Clin Oncol. 2022(suppl 6):9. doi:10.1200/JCO.2022.40.6_suppl.009