FACBC Prostate Therapy Response

The purpose of this study is to assess if using anti-1-amino-3-[18F]fluorocyclobutane-1-carboxylic acid (FACBC or fluciclovine) PET scan will be useful in determining if participants are responding to chemotherapy treatment. Investigators will enroll participants whose cancer has been treated with hormone therapy and now the cancer is not responding to the treatment (castration -resistant), and so therefore will be started on chemotherapy. Investigators aim to enroll thirty participants in this study.

The goal of the investigation is to examine therapeutic monitoring of chemotherapy in castrate resistant prostate carcinoma with anti-3-[18F]FACBC in prostate carcinoma to determine if anti-3-[18F]FACBC amino acid imaging can serve as an accurate and efficient imaging biomarker. Investigators will perform a baseline anti-3-[18F]FACBC PET-CT of the whole body. All participants will also undergo conventional staging including 99mTc methylene diphosphonate (MDP) bone scanning and computed tomography scan (CT) or magnetic resonance imaging (MR) of the abdomen and pelvis which are standard of care at the enrolling institution. This study will not interfere with standard patient evaluation or delay therapy. All 30 participants will receive chemotherapy every 3 weeks for 6 cycles. Participants will undergo a repeat anti-3-[18F]FACBC PET-CT after 1 and 6 cycles and also repeat conventional imaging including bone scanning CT or MR of the abdomen and pelvis after 6 cycles. At the end of the study, the study team will then record the response (or lack thereof) on anti-3-[18F]FACBC PET-CT and correlate that response with response per standard clinical criteria including bone scan uptake for skeletal lesions, CT or MR for soft tissue and skeletal lesions, prostate-specific antigen (PSA) progression or regression, and other clinical parameters such as declining performance status.

Participants with biopsy-proven primary or recurrent castration-resistant prostate carcinoma with skeletal and/or nodal involvement will undergo an FACBC PET-CT scan.

Anti-3-[18F]FACBC is an investigational positron emission tomography (PET) radiotracer being studied given intravenously prior to PET scan.

Conventional imaging such as a MRI, CT, or bone scan will be performed to correlate imaging findings.

Clinical response will be assessed with FACBC PET imaging. The same measurements of the lesions and background structures will be undertaken at baseline and post-therapy scan. The researchers utilized the following parameters to follow response to therapy: maximum standardized uptake value (SUVmax) of most intense lesion each of bone and node, sum and mean SUVmax of up to 5 index lesions for each of bone and node of most intense lesion each of bone and node of the 5 index lesions for each of bone and node. SUVmax measures uptake of the radiotracer by malignant cells. Percent change after therapy, compared to baseline, was calculated and a positive percent increase indicates greater uptake of FACBC by cancer cells.

Prostate Specific Antigen (PSA) serum biomarker will be used to assess response to treatment. PSA level will be collected via blood draw. While a formal cutpoint signifying prostate cancer is not generally used as PSA levels vary between men, in general, higher PSA levels indicate prostate cancer.

Participants will have an MRI or a CT scan to assess response to treatment. Treatment response will be reported as follows: Complete Response (CR) Disappearance of all target lesions. Any pathological lymph nodes (whether target or non-target) must have reduction in short axis to <10 mm. Complete Response Unknown (CRU) Partial Response (PR) At least a 30% decrease in the sum of diameters of target lesions, taking as reference the baseline sum of diameters. Stable Disease (NR/SD) Neither sufficient shrinkage to qualify for PR nor sufficient increase to qualify for PD. Progressive Disease (PD) At least a 20% increase in the sum of diameters of target lesions, taking as reference the smallest sum on study (this may include the baseline sum). The sum must also demonstrate an absolute increase of at least 5 mm.

A CT will be used to assess response to treatment. Treatment response will be reported as follows: Complete Response (CR) Disappearance of all target lesions. Any pathological lymph nodes (whether target or non-target) must have reduction in short axis to <10 mm. Partial Response (PR) At least a 30% decrease in the sum of diameters of target lesions, taking as reference the baseline sum of diameters. Stable Disease (NR/SD) Neither sufficient shrinkage to qualify for PR nor sufficient increase to qualify for PD. Progressive Disease (PD) At least a 20% increase in the sum of diameters of target lesions, taking as reference the smallest sum on study (this may include the baseline sum). The sum must also demonstrate an absolute increase of at least 5 mm.

Each patient underwent 99mTc MDP whole body bone scanning at baseline, and after the 6th cycle. Bone scans findings were interpreted based on recommendations from Prostate Cancer Clinical Trial Working Group 3 (PCCTWG3) using a specialized Bone Scan Assessment Tool. The change in disease response after cycle 6 compared to the baseline assessment is presented here.

Inclusion Criteria: Primary or recurrent castration resistant prostate carcinoma with skeletal and/or nodal involvement not currently undergoing systemic chemotherapy who are about to commence therapy with docetaxel/prednisone. (Note that systemic hormonal targeted therapy including luteinizing hormone-releasing hormone (LHRH) agonists (Lupron or Trelstar), other anti-androgens, and/or Abiraterone or Enzalutamide may be in use.) Ability to lie still for PET scanning Ability to provide written informed consent Exclusion Criteria: Age less than 18 years Inability to lie still for PET scanning Inability provide written informed consent Currently undergoing chemotherapy for organ confined or systemic disease. This does not preclude patients who had previously received upfront docetaxel in the hormone sensitive setting.

Schuster DM, Nieh PT, Jani AB, Amzat R, Bowman FD, Halkar RK, Master VA, Nye JA, Odewole OA, Osunkoya AO, Savir-Baruch B, Alaei-Taleghani P, Goodman MM. Anti-3-[(18)F]FACBC positron emission tomography-computerized tomography and (111)In-capromab pendetide single photon emission computerized tomography-computerized tomography for recurrent prostate carcinoma: results of a prospective clinical trial. J Urol. 2014 May;191(5):1446-53. doi: 10.1016/j.juro.2013.10.065. Epub 2013 Oct 19.