This article has been updated to clarify that the FDA accepted Blue Earth Diagnostics' new drug application for 18F-rhPSMA-7.3 in September 2022.
NEW YORK – Blue Earth Diagnostics on Thursday announced new data supporting its diagnostic agent 18F-rhPSMA-7.3 as a tool for identifying prostate-specific membrane antigen (PSMA)-positive prostate cancers.
Blue Earth Diagnostics, which along with Blue Earth Therapeutics operates under parent firm Bracco Imaging, announced in September 2022 that the US Food and Drug Administration had accepted its new drug application filing for its PET imaging agent 18F-rhPSMA-7.3. While the company is seeking approval for the agent purely as a diagnostic tool, it is developing the agent with an eye toward future therapeutic uses, since 18F-rhPSMA-7.3 shares the same chemical backbone as the radionuclide therapy Blue Earth Therapeutics is developing in PSMA-positive prostate cancer, 177Lu-rhPSMA-10.1. The diagnostic and therapeutic both have the radiohybrid compound but are attached to two different radioactive metals: the diagnostic fluorine-18 and the therapeutic lutetium-177.
Blue Earth Diagnostics' FDA application for the imaging agent contains data from the Phase III LIGHTHOUSE trial. At the American Society of Clinical Oncology's Genitourinary Cancers Symposium on Thursday, the firm shared data on 18F-rhPSMA-7.3's performance in detecting distant metastatic prostate cancer lesions.
Study investigators were asked to identify PSMA-positive metastatic lesions using 18F-rhPSMA-7.3 imaging, and their determinations were compared to findings from biopsies or follow-up conventional imaging. The so-called verified detection rate (VDR) of distant metastases was calculated based on the proportion of patients whose metastatic lesions were identified with the PET imaging agent and then confirmed as true positives by biopsy or by follow-up conventional imaging.
Of 335 patients analyzed, 16 to 28 percent had metastatic lesions that were verified across three readers. In all, 10 percent to 15 percent of patients had verified metastatic lesions. Among 314 patients who tested negative for prostate cancer metastases by conventional imaging at baseline, the VDR was 9 percent to 13 percent across readers.
"Pelvic lymph node dissection or pelvic lymphadenectomy is considered the gold standard in assessing pelvic node lesions, but its use is limited to the planned surgical arena, [and] conventional imaging techniques such as CT and MRI are limited in the information they may provide," Brian Chapin, a surgical urologist at MD Anderson Cancer Center and an investigator in the LIGHTHOUSE study, said in a statement. "18F-rhPSMA-7.3 PET provided clinically valuable information prior to surgery that would likely result in management changes for these patients."