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

This is a first-in-human, Phase I, non-randomized, open-label clinical trial designed to evaluate AZD2284, AZD2287, and AZD2275.

This trial will consist of 2 Parts:

Part A (Imaging):

* Part A (Cold Antibody Exploration): aims to determine the optimal dosing regimen, with or without unconjugated antibody (AZD2275) pre-administration to improve the biodistribution of AZD2287. * Part A Expansion: aims to explore the prevalence of PSMA and STEAP2 expression by imaging.

Part B (Therapeutic):

* Part B (Actinium-225 Dose Escalation): aims to assess the safety, tolerability, and efficacy of escalating doses of AZD2284 informed by the optimal dosing regimen identified in Part A. * Part B Expansion Cohorts 1 and 2: aims to explore efficacy of AZD2284.