Detection of Early Progression with 18F-DCFPyL PET/CT in Men with Metastatic Castration-Resistant Prostate Cancer Receiving Bipolar Androgen Therapy.

Rationale: Bipolar androgen therapy (BAT) is an emerging treatment for metastatic castration resistant prostate cancer (mCRPC). 18F-DCFPyL is a small-molecule positron emission tomography (PET) radiotracer targeting prostate-specific membrane antigen (PSMA). We analyzed the utility of 18F-DCFPyL PET/CT in determining clinical response to BAT. Methods: Six men with mCRPC receiving BAT were imaged with 18F-DCFPyL PET/CT at baseline and after 3 months of treatment. Progression by PSMA-targeted PET/CT was defined as the appearance of any new 18F-DCFPyL-avid lesion. Results: Three of 6 (50%) patients had progression on 18F-DCFPyL PET/CT. All three had stable disease or better on contemporaneous conventional imaging. Radiographic progression on CT and/or bone scan was observed within 3 months of progression on 18F-DCFPyL PET/CT. For the 3 patients that did not have progression on 18F-DCFPyL PET/CT, radiographic progression was not observed for > 6 months. Conclusion: New radiotracer-avid lesions on 18F-DCFPyL PET/CT in men with mCRPC undergoing BAT can indicate early progression.