A Phase I Study of [225Ac]-AZD2284 in Patients With Metastatic Castration-Resistant Prostate Cancer

Main Inclusion Criteria: * Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1. * Histologically confirmed diagnosis of adenocarcinoma of the prostate or neuroendocrine differentiated prostate cancer. * Must have had prior bilateral orchiectomy and/or ongoing androgen-deprivation therapy and a castrate level of serum/plasma testosterone (\< 50 ng/dL or \< 1.7 nmol/L). * At least one metastatic lesion present on baseline Computed Tomography (CT), Magnetic Resonance Imaging (MRI), or bone scan obtained ≤ 28 days prior to the first dose of Investigational Medicinal Product (IMP). Participants may have non-measurable lesions including bone only metastases. * Adequate organ function Main Exclusion Criteria: * Treatment with any radiopharmaceutical within 6 weeks of the first dose of Investigational Medicinal Product (IMP). * Radiation therapy (RT) within 28 days prior to the first dose and all RT-related events have not recovered to Grade ≤ 1. * Administration of any systemic cytotoxic or investigational therapy ≤ 28 days of the first dose of IMP or 5 half-lives, whichever is shorter. * All prior treatment-related adverse events must have resolved to Grade ≤ 1. * Concurrent severe and/or uncontrolled illness not related to cancer and/or social situation that would limit compliance with study requirements. * Known or suspected allergies or contraindications to any of the investigational drugs or any component of the investigational drug formulation. * Clinically relevant proteinuria