Evaluation of the Change in PSMA Expression in Prostate Cancer in Response to Hormonal Therapy

Inclusion Criteria:

* Participant or legally authorized representative (LAR) must provide written informed consent before any study-specific procedures or interventions are performed.
* Participants must have confirmed prostate adenocarcinoma, histologically, or by combined imaging and biochemical markers.
* Age \>= 18 years. Given the nature of the disease in question, only men will be included. Members of all races and ethnic groups will be included.
* Participants must have sites of prostate cancer showing uptake on an initial PSMA PET scan.
* Participants are planned to receive hormonal therapy within eight weeks of the initial PSMA PET. The hormonal therapy agents include:

  * For CSPC: GnRH agonists, GnRH antagonists, first-generation antiandrogen (e.g. bicalutamide), or androgen receptor (AR)-targeted agent (e.g. Abiraterone, Enzalutamide, Apalutamide, Darolutamide)
  * For CRPC: this group of patients are typically on continuous ADT (GnRH agonists or antagonists), which will be continued, and the hormonal therapy they will be started on is an androgen receptor (AR)-targeted agent (e.g. Abiraterone, Enzalutamide, Apalutamide, Darolutamide)
* Life expectancy \> 3 months.
* Cohort 1: Castration resistant prostate cancer with rising PSA (confirmed by two PSA values at least 1 week apart), testosterone \< 50 ng/dL, on continuous ADT at least 4 months, no AR targeted agent in the prior 4 months.
* Cohort 2: Castration sensitive prostate cancer with no ADT or AR targeted agents use in the past 12 months, testosterone \>50 ng/dL

Exclusion Criteria:

* Uncontrolled serious infection.
* Intercurrent illness or condition that would limit compliance with study requirements.
* Participants who have undergone any cancer treatment other than the hormonal therapy (systemic or radiation therapy) or who have started any supplements or herbal medications intended to treat cancer between the baseline PSMA PET and PSMA PET at day 28.