MSG Use With 18F-DCFPyL PET/CT Imaging

18F-DCFPyL is an agent that binds to prostate specific membrane antigen (PSMA). Due to high levels of PSMA in prostate cancer, treatments targeting PSMA have been developed to deliver therapy to these specific target cells. Unfortunately when this treatment is delivered there is radiotracer uptake in the salivary glands and kidneys, not related to cancer, which causes dry mouth and causes patients to stop treatment. It is proposed that having tomato juice containing monosodium glutamate (MSG) may reduce radiotracer uptake in the salivary glands and kidneys and reduce damage to these tissues.

This is a prospective single cohort study to evaluate the utility of MSG in reducing salivary gland radiotracer uptake, in patients who undergo an 18F-DCFPyL Positron Emission tomography / Computer Tomography (PET/CT) scan.

18F-DCFPyL PET/CT scans Each participant will receive 2 18F-DCFPyL PET/CT scans at the BC Cancer - Vancouver Centre, as part of this research sub-study. Each participant will receive tomato juice before each appointment. One visit they will have tomato juice containing MSG and the other will be a placebo (standard tomato juice).

Each study participant will receive a bolus intravenous dose of 18F-DCFPyL. The participant will rest in a comfortable chair for 120 minutes and will then be taken to the PET/CT scanner for images.

24 hour follow-up All participants will be requested to either return to the functional imaging department approximately 24 hours (acceptable range 16-28 hours) after the injection of 18F-DCFPyL and tomato juice consumption or agree to be contacted by phone. The participants will be asked if they experienced any undesirable effects following the administration of 18F-DCFPyL and tomato juice, or in the intervening 24 hours. The local site attending nuclear medicine physician will then make an assessment as to whether these effects are likely related to 18F-DCFPyL and/or tomato juice administration.

The study is expected to take approximately 1 year for accrual.

Eligibility Criteria:
Inclusion Criteria:

* Known prostate cancer with biochemical recurrence after initial curative therapy with radical prostatectomy, presenting with a prostate specific antigen (PSA) greater than 0.4 ng/mL.
* Subjects with findings on other examinations (such as plain x-ray, CT, MRI or bone scintigraphy and others) that are suspicious for metastatic disease but not conclusively diagnostic of metastatic disease, within 3 months of PET scan.
* Known prostate cancer with biochemical recurrence after initial curative therapy with radiation therapy (including brachytherapy), with a PSA level \>2 ng/mL above the nadir after radiation therapy.
* Castration resistant prostate cancer with a minimum PSA of 2.0 ng/mL with 2 consecutive rises above the nadir and castrate levels of testosterone (\<1.7 nmol/L). Treatment does not need to be discontinued before the 18F-DCFPyL scan.
* Eastern Cooperative Oncology Group (ECOG) performance status of 2 or less.

Exclusion Criteria:

* Medically unstable (eg. acute illness, unstable vital signs)
* Unable to lie supine for the duration of imaging
* Unable to provide written consent
* Exceeds safe weight limit of the PET/CT bed (204.5 kg) or unable to fit through the PET/CT bore (diameter 70 cm)
* Severe uncontrolled hypertension (systolic blood pressure above 140 mm Hg and diastolic blood pressure above 90 mm Hg, or systolic blood pressure above 180 mm Hg, or diastolic blood pressure above 110 mg Hg). Patients with controlled hypertension under medication are eligible
* History of severe asthma that has led to hospitalizations or emergency room visits
* History of intolerance to MSG
* History of severe headaches or migraines triggered by food or MSG
* Participants on a sodium/salt restricted diet due to other medical conditions
* No new treatment has started between the first and second 18F-DCFPyL PET/CT