Initial experience with the PET radiotracer anti-1 amino 3 [¹⁸F]fluorocyclobutane-1-carboxylic acid (anti-[¹⁸F]FACBC) in newly diagnosed prostate cancer

Abstract

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Objectives: Currently, there is no definitive imaging technique in the initial diagnosis and staging of prostate cancer. Anti-[¹⁸F]FACBC is a synthetic L-leucine analog which has excellent in-vitro uptake within the DU-145 prostate cancer cell line and within orthotopic implanted prostate tumor in nude rats. There is also little renal excretion compared with ¹⁸F-FDG. The present study examines anti-[¹⁸F]FACBC uptake in patients with newly diagnosed prostate cancer.

Methods: 9 patients with a recent diagnosis of prostate cancer underwent 65 minute dynamic imaging of the pelvis on a GE Discovery PET-CT after IV injection of 300-380 MBq anti-[¹⁸F]FACBC followed by static body images. Each study was evaluated qualitatively and quantitatively. Maximum SUV TACs were recorded in the right and left lobes of the prostate and within lymph nodes. SUV values at 4.5 and 20 min were correlated with presence of disease as defined by clinical, imaging and pathology criteria.

Results: The prostate was not dynamically imaged in 1 patient. In 14/16 lobes, visual analysis correctly identified the presence or absence of focal neoplastic involvement. There was 1 false negative (micro-focus) and 1 false positive (chronic inflammation). Mean +/- SD SUV in the malignant lobes (n=14) were 8.7 +/- 5.7 at 4.5 minutes, and 5.1 +/- 1.4 at 20 minutes; in the benign lobes (n=2), 5 +/- 1.1 at 4.5 minutes and 3.6 +/- .2 at 20 minutes. There was no correlation of SUV to PSA level or Gleason score. Intense uptake was present in metastatic pelvic or retroperitoneal lymph nodes in 2 patients. SUV in a sample of 8 such nodes was 10.5 +/- 3 at 4.5 minutes and 5.9 +/- 2.4 at 20 minutes. All 3 patients who had negative pelvic dissections had no abnormal nodal uptake of FACBC. Chronic prostate inflammation and a clinically benign inguinal node had early moderate uptake (SUV 5.8, 5.8 respectively) which faded at 20 minutes (SUV 3.5, 2.1). Most, though not all, abnormal uptake diminished to background by 65 minutes.

Conclusions: In this small patient sample, anti-[¹⁸F]FACBC uptake is elevated in primary and metastatic prostate carcinoma. Inflammation demonstrated early though not delayed uptake. Future research should be directed towards pathologic mapping, clinical follow-up, and developing a strategy for clinical imaging.

Research Support (if any): This research was sponsored by Nihon Medi-Physics Co., Ltd.