AZD5305 vs Placebo in Men with Metastatic Castration-Sensitive Prostate Cancer Receiving Physician's Choice New Hormonal Agents.

Prior treatment

• Participants with a history of MDS/AML or with features suggestive of MDS/AML (as determined by prior diagnostic investigation). In case there is no clinical MDS/AML suspicion, no specific screening for MDS/AML (by BM/bone biopsy) is required.
• Any prior anticancer pharmacotherapy or surgery for metastatic prostate cancer, with the following exceptions: a) ≤ 4 months ADT for metastatic disease (per inclusion criterion 4). b) Radiation therapy (for example radiation therapy to the prostate for participants with low volume metastatic disease or palliative radiation therapy to treat symptoms resulting from metastatic disease). Radiation therapy needs to have been completed > 4 weeks prior to randomisation for wide field radiation therapy and > 2 weeks for limited field radiation therapy. Participants should have fully recovered from any clinically significant adverse events. c) Surgical therapy to treat symptoms from metastatic disease if it was completed at least 4 weeks prior to first day of dosing and participant fully recovered from any clinically significant AEs.
• Prior treatment within 14 days with blood product support or growth factor support.
• Refractory nausea and vomiting, chronic gastrointestinal diseases, inability to swallow the formulated product or previous significant bowel resection that would preclude adequate absorption of AZD5305 and/or the assigned NHA.
• History of another primary malignancy, with the following exceptions: a) Adequately resected non-melanoma skin cancer. b) Curatively treated in situ disease. c) Malignancy treated with curative intent ≥ 3 years before the first dose of study intervention, and with no known active disease during the intervening time period.
• Persistent toxicities (CTCAE Grade ≥ 2) caused by previous anticancer therapy.
• Spinal cord compression or brain metastases unless asymptomatic, stable, and not requiring steroids for at least 4 weeks prior to start of study intervention.

Other illness

• Cardiac criteria, including history of arrythmia and cardiovascular disease.
• Participants with any known predisposition to bleeding.
• Any history of persisting (> 2 weeks) severe cytopenia.

Other

• Patients in whom the standard of care is judged by the investigator to be docetaxelin combination with darolutamide.
• Participants who are unevaluable for both bone and soft tissue progression.

• Male ≥ 18 years of age.
• Participants must use a condom from signing ICF, during study intervention, and for 6 months after the last dose of study drug, with all sexual partners.
• Histologically documented prostate adenocarcinoma which is de novo or recurrent and castration-sensitive. Participants with pathologic features of small cell, neuroendocrine, sarcomatoid, spindle cell, or signet cell histology are not eligible.
• Metastatic disease as documented by the investigator prior to randomisation, with clear evidence of ≥ 1 bone lesion and/or ≥ 1 soft tissue lesion that is suitable for repeated assessment with CT and/or MRI.
• Participant is receiving ADT with a GnRH analogue or has undergone bilateral orchiectomy starting ≥ 14 days and < 4 months prior to randomisation.
• ECOG performance status of 0 or 1 with no deterioration over the 2 weeks prior to randomisation.
• Provision of FFPE tumour tissue sample and blood sample (for ctDNA).
• Confirmed HRRm status by central tumour tissue and/or ctDNA test is required to determine cohort eligibility.
• Adequate organ and bone marrow function as described in study protocol.
• Participants must not father children or donate sperm from signing ICF, during the study intervention and for 6 months after the last dose of study intervention.