This clinical trial evaluates the use of an imaging scan (18F-rhPSMA-7.3 positron emission tomography [PET]/magnetic resonance imaging [MRI]) for identifying patients who are at risk of having their disease spread to the lymph nodes in those undergoing radical prostatectomy for prostate cancer that has not spread to other parts of the body (localized). Prostate specific membrane antigen (PSMA) PET/computed tomography (CT) has emerged as an option to stage newly diagnosed high risk prostate cancer patients. PSMA PET/CT has demonstrated improved diagnostic accuracy for identifying metastasis. PET is procedure in which a small amount of radioactive glucose (sugar) is injected into a vein, and a scanner is used to make detailed, computerized pictures of areas inside the body where the glucose is used. Because cancer cells often use more glucose than normal cells, the pictures can be used to find cancer cells in the body. MRI is procedure in which radio waves and a powerful magnet linked to a computer are used to create detailed pictures of areas inside the body. These pictures can show the difference between normal and diseased tissue. This study may help researchers learn whether 18F-rhPSMA-7.3 PET/ MRI may improve predicting which patients are at risk of lymph node metastases and who are suitable candidates for pelvic lymph node dissection in patients with localized high-risk prostate cancer undergoing radical prostatectomy.

PRIMARY OBJECTIVE:

I. To investigate the diagnostic ability of flotufolastat F-18 gallium (18F-rhPSMA-7.3) PSMA PET/MRI prior to radical prostatectomy in newly diagnosed, high-risk prostate cancer patients.

SECONDARY OBJECTIVES:

I. Calculating the specificity, positive-predictive value, and negative-predictive value for the detection of lymph node positivity.

II. Investigating the rates of biochemical recurrence (BCR) as measured by post-operative prostate specific antigen (PSA) (PSA > 0.20) at pre-defined timepoints in patients.

OUTLINE:

Patients receive 18F-rhPSMA-7.3 intravenously (IV) and undergo PET/MRI up to 30 days prior to standard of care (SOC) robotic radical prostatectomy with bilateral pelvic lymph node dissection. Patients also undergo CT/MRI or bone scan/PET, as well as tissue collection during screening.

Upon completion of study treatment, patients are followed up at 6 weeks, 3 months, 9 months, and 12 months post-surgery.

Inclusion Criteria:

• Male subjects ≥ 30 and ≤ 85 years old
• Primary diagnosis of prostate cancer selected for surgical intervention (radical prostatectomy with extended lymph node dissection)
• Primary diagnosis of untreated American Urological Association (AUA) guidelines high-risk localized prostate cancer, hormone-naïve prostate cancer via contrast enhanced prostate MRI + tissue sampling
• Planned elective radical prostatectomy with extended pelvic lymph node dissection
• Clinical oligometastatic disease with ≤ 3 nodes positive on preoperative standard of care imaging of prostate region within 6 months of surgery
• Patient agrees to comply with the investigator instructions
• Patient agrees to comply with the follow-up surveillance schedule
• Have ability to provide full written consent

Exclusion Criteria:

• High-risk cancer planned for neoadjuvant therapy
• Patients with a history of more than two weeks treatment with immunosuppressants (including systemic corticosteroids), cytotoxic chemotherapy within one month prior to initial screening, or who receive such medications during the screening period, or who are anticipated to require such medications during the course of the study
• Patients that have had prior hormonal therapy such as Lupron or oral antiandrogens ≤ 12 weeks prior to registration
• Clinical oligometastatic disease with > 3 nodes positive preoperative standard of care imaging of prostate region
• Previous history of pelvic radiation
• Patients with obesity defined as body mass index (BMI) > 40 kg/m^2
• History of prior laparoscopic inguinal hernia repair with mesh
• Scheduled at the time of screening to undergo chemotherapy, radiation, hormone therapy, or open surgery during the study period
• Inability to lie still for 75 minutes during 18F-rhPSMA-7.3 PSMA PET-MRI imaging
• Any neurologic disorder or psychiatric disorder that might confound postsurgical assessments
• Has any condition(s), which seriously compromises the subject's ability to participate in this study, sign consent, or has a known history of poor adherence with medical treatment
• Received administration of an investigational drug within 30 days prior to study registration, and/or has planned administration of another investigational product or procedure during participation in this study