RESUMO
Monitoring therapeutic response in patients with metastatic castration-resistant prostate cancer (mCRPC) can be challenging. We set out to determine if 18F-fluciclovine PET/CT could be a useful imaging biomarker for response to docetaxel chemotherapy in patients with mCRPC. Seven patients with mCRPC had 18F-fluciclovine PET/CT scheduled at baseline and after 1 and 6 cycles of chemotherapy. The sum of SUVmax from the prostate/bed and up to 5 metastatic bone and soft tissue/visceral lesions were recorded. The SUVpeak of the hottest lesion (PERCIST-like) was also recorded. In comparison to the baseline scan, a decrease of ≥30% was considered response; new lesions or >30% increase was progressive disease; change of <30% was stable disease. Bone scintigraphy and CT were acquired at baseline and after the 6th cycle. Response assessment was based on the Prostate Cancer Clinical Trial Working Group 3 recommendations. All (7/7) enrolled patients completed the 1st and 2nd scans, while 4/7 patients completed all 3 scans. PET response correlated with PSA response in 3/7 (42.9%) patients after 1 cycle of docetaxel, and 3/4 (75%) patients after 6 cycles of docetaxel, respectively. Bone scan and CT correlated with PSA response in 1/4 (25%) patients. There was no significant correlation between baseline 18F-fluciclovine PET parameters or changes in PET parameters and time to PSA progression. In conclusion, this exploratory study showed that 18F-fluciclovine PET/CT has better correlation with PSA response than CT or bone scan in patients with mCRPC treated with docetaxel. 18F-fluciclovine PET/CT however did not predict time to PSA progression.