Study of AZD5305 When Given in Combination With New Hormonal Agents in Patients With Metastatic Prostate Cancer

The study consists of 2 parts, Part A and Part B. Part A consists of the dose escalation cohorts and will include patients with metastatic castration resistant prostate cancer (mCRPC) or metastatic castration-sensitive prostate cancer (mCSPC); Part B consists of dose expansion cohorts and will include patients with mCSPC only. Part A comprises 4 individual arms each evaluating the safety, tolerability, and preliminary efficacy of AZD5305 in combination with a specific new hormonal agent (NHA). Part B comprises up to 4 individual arms (arms to be opened at Sponsor's discretion) each investigating the preliminary efficacy and aims to further build on the safety data for the combination of AZD5305 with a specific NHA. Approximately 783 patients will be enrolled and screened to ensure the required number of evaluable patients in each part and arm are enrolled. For Part A, 356 patients may be screened to obtain up to approximately 308 patients that can be assigned to study treatments across all study arms (1 to 4). For Part B dose expansion cohorts, up to 427 patients may be screened to obtain up to approximately 360 patients that can be assigned to study treatments across all study arms (1 to 4). Study treatment administration will continue until disease progression, initiation of alternative anticancer therapy, unacceptable toxicity, withdrawal of consent, or other reasons to discontinue study treatment occur.