Pilot evaluation of 1-amino-2-[18F] fluorocyclopentane-1-carboxylic acid (anti-2-[18F] FACPC) PET-CT in recurrent prostate carcinoma

1266 Objectives Aminocyclopentane carboxylic acid (ACPC) is an unnatural alicyclic amino acid which was originally developed as a therapeutic agent for malignant tumors via competitive inhibition of valine synthesis by tumor cells. Anti-2-[18F]FACPC is an ACPC analogue with high uptake in the DU-145 prostate cancer cell line in-vitro. Methods 5 patients with elevated PSA (1.1-20.5 ng/mL) after curative therapy for prostate carcinoma, underwent 60 minute dynamic imaging of the pelvis on a GE Discovery PET-CT after IV injection of 193-340 MBq of anti-2-[18F]FACPC. Uptake was compared against recently performed PET scans in the same patients with the leucine analogue, anti-[18F]FACBC, at similar time points and validated via pathology, clinical and imaging follow-up. Results At 5 min, mean(SD) SUVmax of known lesions is 4.1(1.3) for FACPC and 4.3(1.1) for FACBC. Yet, blood pool is significantly higher for FACPC with SUVmean 2.7(0.5) compared to FACBC 1.3(0.3). Lesion/blood pool SUV ratio for FACPC is 1.4(0.5) vs. 3.4(0.8) for FACBC. At 20 min, mean(SD) SUVmax of known lesions is 2.8(1.0) for FACPC and 3.9(0.8) for FACBC. Yet, bladder demonstrates intense activity for FACPC with SUVmean of 41.8(31) compared with FACBC 1.5(0.7). Lesion/bladder SUV ratio for FACPC is 0.8(1.6) vs. 3.2(1.2) for FACBC. Bone lesions in one patient were only identified with FACBC. Conclusions While prostate bed lesions are visible on early imaging with anti-2-[18F]FACPC, there is relatively high blood pool obscuring evaluation of nodal disease. As blood pool fades, nodal uptake decreases and high bladder activity then obscures pelvic structures. Compared with anti-[18F]FACBC in these 5 patients, imaging characteristics for anti-2-[18F]FACPC are unfavorable for pelvic prostate carcinoma detection. Research Support Research sponsored by the Georgia Cancer Coalition