Phase IIa Clinical Trial of Trans-1-Amino-3-18F-Fluoro- Cyclobutane Carboxylic Acid in Metastatic Prostate Cancer

Objective(s): We performed a phase IIa clinical trial of trans-1-amino-3-18Ffluoro-cyclobutane carboxylic acid (anti-18F-FACBC), a synthetic amino acid analog for PET, in patients with metastatic prostate cancer. Methods: The study subjects consisted of 10 untreated prostate cancer patients having lymph node and/or bone metastasis. Five patients underwent whole-body PET 5 and 30 min after intravenous injection of anti-18F-FACBC. The other five patients underwent 60 min dynamic PET of the pelvis. Safety assessment was performed before and 24 h after injection. PET/CT images were assessed visually, and time courses of anti-18F-FACBC uptake were evaluated from dynamic imaging. Results: Two mild adverse events were observed and resolved without treatment. All 10 patients showed increased accumulation of anti-18F-FACBC in the primary prostate lesion. CT revealed five enlarged lymph nodes indicating metastasis, and all showed increased uptake. Additionally, anti-18F-FACBC PET delineated unenlarged lymph nodes as hot spots. Anti-18F-FACBC PET demonstrated metastatic bone lesions, similar to conventional imaging. In one of two patients with lung metastasis, some lesions showed increased uptake. Regarding the time course, increased uptake of anti-18F-FACBC in the lesion was demonstrated immediately after injection, followed by gradual washout. Conclusion: The results of this phase IIa clinical trial indicated the safety of anti-18F-FACBC in patients with prostate cancer and the potential of anti-18F-FACBC PET to delineate primary prostate lesions and metastatic lesions. This clinical trial was registered as JapicCTI-101326.