18F-DCFPyL Imaging as a Method to Assess Treatment Response to Stereotactic Body Radiation Therapy

Overview

Background: Identifying medium- and high-risk prostate cancer early may allow for treatments to work. But identification can be hard. Researchers want to see if a radiotracer used during PET scans can help. Objective: To test how an imaging agent called 18F-DCFPyL detects response to standard prostate cancer treatment. Eligibility: People ages 18 and older with newly diagnosed prostate cancer who have no evidence of distant metastatic disease and plan to get stereotactic body radiation therapy (SBRT) with or without androgen deprivation therapy (ADT). Design: Participants will be screened with: Medical history Physical exam Blood tests MRI Participants will have baseline MRI and PET/CT scans. For the MRI, they may get a contrast agent by IV injection. For the PET/CT scan, they will get an IV injection of 18FDCFPyL. About 1 to 2 hours later, they will get the PET/CT scan. During the scans, participants will lie on their back and remain still for 45 minutes to 1 hour. These scans will be repeated at different points during the study. Participants will get SBRT with or without ADT. Participants will complete questionnaires about their quality of life. Participants will be asked about any symptoms they are having. They will also be asked about medications they are using. They may have a physical exam. Participants will give blood and urine samples. They will give a tumor sample from a biopsy they have had in the past. After treatment, participants will have follow-up visits. These will occur 1 month after treatment, then every 3 months for a year, and then every 6 months for 1 more year.

Background: Radiotherapy is a highly effective treatment for localized prostate cancer; however, recurrence is more common in patients with unfavorable intermediate and high-risk prostate cancer, and is usually diagnosed by rising prostate specific antigen (PSA - biochemical failure). Early identification of disease persistence or recurrence before meeting criteria of biochemical failure may allow effective potentially curative salvage treatment, but identification of local recurrence or persistence at early stages is challenging. CT imaging is relatively insensitive at localizing recurrence, while MRI is more sensitive for local recurrence but is non-specific. Prostate specific membrane antigen (PSMA) targeted PET imaging was recently FDA approved for imaging men with suspected prostate cancer metastases who are potentially curable by radiation or surgery. PSMA based imaging has been used in prospective trials to define extent of disease and to alter radiation treatment volumes. 18F-DCFPyL, a second generation PSMA PET agent that binds with high affinity to PSMA yet clears rapidly from the blood pool, has recently been approved by the FDA as a method to stage high risk cancer and detect recurrent disease. Primary Objective: To define 18F-DCFPyL PET/CT imaging response in participants with localized prostate cancer after treatment with stereotactic body radiation therapy (SBRT) with or without androgen deprivation therapy (ADT). Eligibility: Biopsy proven localized prostate cancer in whom prostate SBRT with or without ADT is appropriate therapy Must have at least 1 MRI detected, biopsy proven site of prostate cancer. ECOG 0-2 Design: This is a single center, prospective study aimed at recruiting the following cohorts: Up to 40 evaluable participants with presumed localized prostate cancer (intermediate or high risk) scheduled to undergo radiotherapy with systemic androgen deprivation therapy. Up to 40 evaluable participants with presumed localized prostate cancer (intermediate or high risk) scheduled to undergo SBRT without androgen deprivation therapy. Up to 20 evaluable participants with presumed localized prostate cancer (intermediate or high risk) scheduled to undergo radiotherapy with localized androgen deprivation therapy. Participants receiving neoadjuvant androgen deprivation therapy will undergo a second 18F-DCFPyL PET/CT and multiparametric MRI (mpMRI) at 8 weeks after initiation of ADT but before SBRT. All participants will undergo 18F-DCFPyL PET/CT and mpMRI 6 months following completion of SBRT and at recurrence, if applicable. Participants will be followed for up to 2 years after completion of SBRT to evaluate longitudinal quality of life and biochemical control.