Impact of Monosodium Glutamate on 68GA-PSMA-11, PET Imaging Biodistribution in Patients With Prostate Cancer

PRIMARY OBJECTIVE: I. To determine the effect of monosodium glutamate (MSG) administration (glutamate supplementation) on the salivary gland uptake of gallium Ga 68-labeled PSMA-11 (68Ga-PSMA-11). SECONDARY OBJECTIVES: I. To determine the effect of MSG administration on renal 68Ga-PSMA-11 uptake. II. To determine the effect of MSG administration on tumor 68Ga-PSMA-11 uptake. III. To determine if 68GA-PSMA-11 is excreted in the saliva. IV. Safety of MSG administration both oral ingestion and oral-salivary stimulation. OUTLINE: Patients are randomized to 1 of 2 arms. Arm I: Patients receive gallium Ga 68-labeled PSMA-11 intravenously (IV) and undergo a positron emission tomography (PET)/computed tomography (CT) scan on day 1. Within 2 weeks (days 2-14), patients receive MSG orally (PO) over 10 minutes and receive a second dose of gallium Ga 68-labeled PSMA-11 IV, followed by a second PET/CT scan. Patients also undergo collection of saliva at 0, 30, and 60 minutes after gallium Ga 68-labeled PSMA-11 injection and 90 minutes after PET/CT. Arm II: Patients receive gallium Ga 68-labeled PSMA-11 IV and undergo a PET/CT scan on day 1. Within 2 weeks (days 2-14), patients receive a second dose of gallium Ga 68-labeled PSMA-11 IV immediately followed by MSG applied in the mouth over 30 seconds every 10 minutes for a total of 6 times, and then undergo a second PET/CT scan. Patients also undergo collection of saliva at 0, 30, and 60 minutes after gallium Ga 68-labeled PSMA-11 injection and 90 minutes after PET/CT.