18F-fluciclovine PET in Metastatic Castration Resistant Prostate Cancer Treated With Life Prolonging Therapies

This is a pilot phase 2 single-arm study, of men with metastatic castration-resistant prostate cancer (mCRPC). Patients will be treated with any of the approved life-prolonging therapies: abiraterone 1000 mg daily plus prednisone 5 mg (or dexamethasone 0.5 mg) daily, enzalutamide 160 mg daily, or docetaxel 50 mg/m2 every two weeks or 75 mg/m2 every three weeks.

Prostate cancer is a hormonally-driven disease and androgens are key in the growth of both normal prostate and prostate cancer cells. Once mCRPC is evident, most patients receive a second-generation hormonal therapy to further suppress the synthesis or androgens (abiraterone) and to block androgen receptor (AR) activation, nuclear translocation and DNA binding (enzalutamide). Conventional imaging of prostate cancer has limitations in staging, restaging after biochemical relapse, and response assessment. Functional imaging with positron emission tomography (PET) can target various aspects of tumor biology and is clearly superior in the detection of extra-prostatic disease. 18F-fluciclovine is a synthetic amino acid transported across mammalian cell membranes by amino acid transporters that are upregulated in prostate cancer cells. 18F-fluciclovine is approved for PET imaging to identify sites of prostate cancer recurrence in men with rising prostate specific antigen (PSA) following prior definitive treatment. This study describes the changes in 18F-fluciclovine PET scan and compare these results with PSA and conventional computerized tomography (CT) and bone scans, in mCRPC patients treated with abiraterone acetate-prednisone, enzalutamide or docetaxel.