231 Background: Conventional imaging of advanced prostate cancer (computerized tomography and nuclear bone scintigraphy) is limited and indicates a need for a more specific molecular imaging probe. DCFBC is a radiolabeled PET agent that binds with high affinity to prostate specific membrane antigen (PSMA), which is overexpressed in almost all prostate cancers and through whole-body non-invasive functional imaging, may provide new information on the expression of PSMA. We compare the uptake of DCFBC in bone with respect to NaF PET/CT in metastatic prostate cancer patients. DCFBC has added capability to detect soft tissue metastasis whereas NaF is confined to secondary effects of bone disease. Methods: Subjects with known or suspected prostate cancer metastasis underwent DCFBC PET/CT imaging performed at 1 hour and 2 hours after IV bolus injection of 8 mCi of DCFBC. Patients also underwent a whole body NaF PET/CT scan within 3 weeks of DCFBC PET/CT to assess for bone metastases. Patients received 3 mCi of NaF IV bolus and then were imaged 1hour post injection. PSA levels and antiandrogen therapy status were obtained at the time of DCFBC imaging. Results: Fifteen patients have been preliminarily analyzed. PSA ranged from < .01 to 4379 ng/mL. NaF identified bone lesions in 10 patients but matching focal DCFBC uptake was only seen in 3 patients. DCFBC additionally showed lymph node metastasis in 1of these 3 patient. There were 5 patients without focal abnormal bone uptake on NaF or DCFBC. In this group, 4 of 5 patients had focal DCFBC uptake in lymph nodes or soft tissue lesions. Ten patients were on some form of androgen deprivation therapy (ADT). For those on ADT, 7 of 10 patients had positive findings on NaF, compared to 2 of 10 patients on DCFBC. Conclusions: DCFBC uptake in bone metastasis does not routinely correspond to focal NaF uptake which could be due to distinct mechanisms of tracer uptake and tumor biology. There is an inverse association in focal bone findings when comparing each tracer on antiandrogen therapy. Through whole-body non-invasive functional imaging and further study, DCFBC may prove useful in characterizing prostate cancer based on PSMA expression. Clinical trial information: NCT02190279.
Targeting glucocorticoid metabolism in prostate cancer
