FPI-2265 (225Ac-PSMA-I&T) for Patients with PSMA-Positive Metastatic Castration-Resistant Prostate Cancer (mCRPC)

Key Inclusion Criteria:

- Ability to understand and sign an approved informed consent form (ICF) and comply
with all protocol requirements.

- Phase 2: Eastern Cooperative Oncology Group (ECOG) Performance Status 0 or 1

- Diagnosis of adenocarcinoma of prostate proven by histopathology.

- Must have had prior orchiectomy and/or ongoing androgen-deprivation therapy and a
castrate level of serum/plasma testosterone

- Progressive mCRPC.

- Must have been previously treated with lutetium-PSMA therapy (lutetium-177
vipivotide tetraxetan or other lutetium-177-PSMA RLT). Treatment must have been
completed >6 weeks prior to the first dose of study drug.

- Participants with known BRCA mutations should have received FDA-approved therapies
such as PARP inhibitors, per Investigator discretion.

- Positive PSMA PET/CT scan

- Adequate organ function

- For participants who have partners of childbearing potential: Partner and/or
participant must not be planning to conceive and must use a method of birth control
with adequate barrier protection deemed acceptable by the Principal Investigator
during the study treatment and for six months after last study drug administration.

Key Exclusion Criteria:

- Participants who received more than two prior lines of cytotoxic chemotherapy for
CRPC.

- Phase 2: participants who progress within two cycles of prior treatment with
177Lu-PSMA therapy

- All prior treatment-related adverse events must have resolved to Grade ≤1 (CTCAE
v5.0). Alopecia and stable persistent Grade 2 peripheral neuropathy may be allowed
at the discretion of the Investigator.

- Participants with known, unresolved, urinary tract obstruction are excluded.

- Administration of any systemic cytotoxic or investigational therapy ≤30 days of the
first dose of study treatment or five half-lives, whichever is shorter. Completion
of large-field external beam radiotherapy ≤four weeks of the first dose of study
treatment.

- Participants with a history of central nervous system (CNS) metastases are excluded
except those who have received therapy

- Participants with any liver metastases will be excluded from the Phase 2 segment of
the study.

- Participants with skeletal metastases presented as a superscan on a ⁹⁹ᵐTc bone scan.

- Previous or concurrent cancer that is distinct from the cancer under investigation
in primary site or histology, except treated cutaneous basal cell carcinoma or
squamous cell carcinoma and superficial bladder tumors. Any cancer curatively
treated >two years prior to the first dose of treatment is permitted.

- Concurrent serious (as determined by the investigator) medical conditions

- Major surgery ≤30 days prior to the first dose of study treatment.