68Ga-PSMA-11 patients with newly diagnosed and recurrent prostate cancer (Firefly Study): Preliminary results.

Abstract

54 Background: A primary challenge facing oncologists is the accurate identification of the source of the rising PSA in the recurrent disease setting and the failure of proper staging at the time of initial therapy. PSMA imaging allows for progress in this regard, however access remains an issue. As such, we designed the Firefly study to offer PSMA imaging to patients between May 2021 and May 2022, to better characterize their disease. Methods: This is a phase II expanded access intermediate sized clinical trial using 68Ga-PSMA-11 (Telix Pharma cold kit) under Tulane’s own Investigational New Drug (IND). Clinical trial information: NCT04854369. Two cohorts are utilized, recurrent disease with a PSA > 0.2 or > 2.0 post-radiation, and newly diagnosed high risk or oligo-metastatic patients as assessed by conventional imaging. Between May 2021 and May 2022, a total of 90 patients were enrolled. The study was designed for a maximum of 300 patients but was terminated when access to insurance approved PSMA scans was available. Patients received 1.8–2.2 MBq/kg body weight with 68Ga-PSMA-11 (per EANM guidelines). The lower and upper limits of the dose were set to 3 to 7 mCi respectively. Primary Objective(s): Utilize 68Ga-PSMA-11 PET to define uptake location for localization of prostate cancer metastatic sites in patients prior to initial therapy, and in both local recurrences and metastatic sites in patients with recurrent disease after initial therapy. Secondary Objectives: To assess the therapeutic consequences of 68Ga-PSMA-11 PET/CT imaging in prostate cancer patients with and without prior treatment. Results: Of the 90 patients enrolled 81 were in the recurrent disease cohort and nine had newly diagnosed disease. Of the 81 patients with recurrent disease; 30 were known metastatic and were scanned with the intention of application for expanded access to 177Lu-PSMA-617, 8 received radiation for their oligometastases, 12 received a combination of radiation and initiation of hormone therapy, 13 continued surveillance, 5 were sent for salvage therapy, 13 were treated with novel hormones. Of the 9 patients with newly diagnosed disease all of them were negative for metastasis on conventional imaging. However, when scanned with 68Ga-PSMA-11, 7/9 had a positive PSMA scan. A lesion in the prostate was identified in 2/7 patients, 2/7 were found to have de novo metastatic disease to the lymph nodes and 3/7 were found to have bone metastasis. All these patients were treatment naïve and 5/7 had changes to their planned definitive treatment plan based on these results, as high-risk patients found to have previously unidentified de novo metastatic disease. Conclusions: Further analysis of the data is planned to complete secondary objectives; however, this study demonstrates the potentially meaningful impact of PSMA imaging for patient treatment planning and individualized care. Clinical trial information: NCT04854369 .