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 (defined as 1 lesion with positive uptake on bone scan) and/or ≥ 1 soft tissue lesion (measurable and/or non-measurable) that can be accurately assessed at baseline and is suitable for repeated assessment with CT and/or MRI. Participants with metastatic disease identified by PSMA-PET only, will not be eligible. Participants with disease limited to regional pelvic lymph nodes only are not eligible.
Participant is receiving ADT with a GnRH analogue or has undergone bilateral orchiectomy starting ≥ 14 days and < 4 months prior to randomisation with no radiographic evidence of disease progression or rising PSA levels prior to first day of dosing. Participant must remain on ADT throughout the study and be a candidate for treatment with an NHA. Combination with first generation AR antagonists to counter testosterone flare is permitted until randomisation. Note: Due to the interaction between relugolix and enzalutamide, this combination of ADT and NHA is not allowed. Relugolix is otherwise permitted.
ECOG performance status of 0 or 1 with no deterioration over the 2 weeks prior to randomisation.
Minimum life expectancy of 6 months.
Provision of a FFPE tumour tissue sample and a blood sample (for ctDNA) as specified in the Laboratory Manual is required to determine HRRm status (refer to Section 8.8 and to Table 7).
Confirmed HRRm status by central tumour tissue and/or ctDNA test is required to determine cohort eligibility as described below:
Participants will be considered eligible for the HRRm Cohort if a loss of function mutation (deleterious/pathogenic or suspected deleterious/likely pathogenic in at least one of the genes BRCA1, BRCA2, ATM, CDK12, PALB2, RAD51B, RAD51C, RAD51D, and BARD1) is detected by either central tumour tissue or central ctDNA test, ie, a positive HRRm result reported by one assay (tissue or ctDNA) is sufficient irrespective of the result of the other assay;
Participants will be considered eligible for the Non-HRRm Cohort if no gene mutation (in any of BRCA1, BRCA2, ATM, CDK12, PALB2, RAD51B, RAD51C, RAD51D, and BARD1) is detected by either tumour tissue or ctDNA test and a participant must have a non-HRRm tumour tissue test result. Participants without a valid non-HRRm tumour tissue result will not be eligible for randomisation into the Non-HRRm Cohort. For details see Table 7.
Adequate organ and bone marrow function as follows:
Haemoglobin ≥ 10.0 g/dL with no blood transfusion in the 14 days prior to randomisation;
Absolute neutrophil count ≥ 1.5 × 10^9 /L with no growth factor support in the 28 days prior to randomisation;
Platelet count ≥ 100 × 10^9 /L;
Serum albumin ≥ 3.0 g/dL;
INR ≤ 1.5. Participants receiving oral anticoagulants may be enrolled with an INR < 2. Participants with other causes of INR increase such as haematologic disorders or impaired hepatic synthesis should be excluded;
Total bilirubin ≤ 1.5 × the ULN or ≤ 3 × ULN in the presence of documented Gilbert’s syndrome (unconjugated hyperbilirubinaemia);
Alanine aminotransferase and AST ≤ 2.5 × ULN; for participants with hepatic metastases, ALT and AST ≤ 5 × ULN (please see Appendix E 6 and Appendix E 4.2);
Estimated GFR (eGFR) of ≥ 45 mL/min/1.73 m^2 as determined by CKD-EPI formula (Inker et al 2021):
For participants with SCr ≤ 0.9 mg/dL (≤ 79.56 µmol/L), use the following formula: 142 x (SCr/0.9)-0.302 × 0.9938Age (years);
For participants with SCr > 0.9 mg/dL (> 79.56 µmol/L), use the following formula: 142 x (SCr/0.9)-1.200 × 0.9938Age (years).
Participants with a history of MDS/AML or with features suggestive of MDS/AML (as determined by prior diagnostic investigation). Specific screening for MDS/AML is not required.
Participants with any known predisposition to bleeding (eg, active peptic ulceration, recent [within 6 months] haemorrhagic stroke, proliferative diabetic retinopathy).
Any history of persisting (> 2 weeks) severe cytopenia due to any cause (eg, absolute neutrophil count < 0.5 × 10^9 /L or platelets < 50 × 10^9 /L).
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:
Adequately resected non-melanoma skin cancer;
Curatively treated in situ disease;
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. Participants with side effects that are not reasonably expected to affect the safety of the participant on study intervention in the opinion of the investigator (eg, ADT-related side effects) may be included if agreed with the Study Clinical Lead.
Spinal cord compression or brain metastases unless asymptomatic, stable, and not requiring steroids for at least 4 weeks prior to start of study intervention. A minimum of 2 weeks must have elapsed between the end of brain radiotherapy and signing the main study ICF.
Any of the following cardiac criteria:
Mean resting corrected QT interval (QTcF) > 470 milliseconds obtained from triplicate ECGs and averaged, recorded 5 minutes apart;
Congenital long QT syndrome, family history of long QT syndrome, or unexplained sudden death under 40 years of age in first-degree relatives.
History of arrhythmia (multifocal premature ventricular contractions, bigeminy, trigeminy, ventricular tachycardia), which is symptomatic or requires treatment (CTCAE Grade 3), symptomatic or uncontrolled atrial fibrillation despite treatment, or asymptomatic sustained ventricular tachycardia. Participants with atrial fibrillation controlled by medication or arrhythmias controlled by pacemakers may be permitted upon discussion with the AstraZeneca study physician.
Other cardiovascular disease as defined by any of the following:
Symptomatic heart failure (as defined by New York Heart Association class ≥ 2);
Acute coronary syndrome /acute myocardial infarction, unstable angina pectoris, coronary intervention procedure with percutaneous coronary intervention or coronary artery bypass grafting within 6 months prior to randomisation;
Cardiomyopathy of any aetiology;
Presence of clinically significant valvular heart disease;
Left ventricular ejection fraction ≤ 50% measured by echocardiogram or MUGA scan at screening or based on assessment performed within 6 months prior to randomisation;
Transient ischaemic attack, or stroke within 6 months prior to randomisation;
Participants with symptomatic hypotension at screening;
Uncontrolled hypertension despite medical management.
Evidence of active and uncontrolled hepatitis B and/or hepatitis C. Screening for hepatitis B and hepatitis C is not required. Participants previously exposed to hepatitis B or hepatitis C are eligible if they meet 1 of the following criteria:
Are negative for HBsAg and anti-HBc; or
Are HBsAg+ and anti-HBc+ (chronic hepatitis B), and meet conditions i to iii below:
HBV DNA viral load < 2000 IU/L;
Have normal aminotransferase values, or, if liver metastases are present, abnormal aminotransferase, with a result of AST/ALT < 3 x ULN, which are not attributable to HBV infection;
Start antiviral treatment at least 2 weeks prior to the first dose of study intervention and maintain antiviral treatment during the interventional period. For permitted concomitant therapies, refer to Appendix I.
Are anti-HBc positive, HBsAg negative, and have HBV DNA < 2000 IU/L;
Participants positive for HCV antibody are eligible only if polymerase chain reaction is negative for HCV RNA;
NOTE: Inclusion of this group of participants should be carefully considered if participant has no access to hepatology service and/or is currently in need of antiviral treatments.
Evidence of active and uncontrolled HIV infection. Participants with controlled HIV need to meet the following criteria: undetectable viral RNA load less than 400 copies/mL in the last 4 weeks prior to first dose of study intervention, CD4+ count of ≥ 350 cells/µL, no history of AIDS-defining opportunistic infection within the past 12 months, and stable on the same anti-HIV medications (as permitted in Appendix I) for at least 6 months. Screening for HIV is not required. NOTE: Inclusion of this group of participants should be carefully considered if participant has no access to specialist service and/or is not stabilised on antiviral treatments.
Active tuberculosis infection (clinical evaluation that may include clinical history, physical examination and radiographic findings, or tuberculosis testing in line with local practice).
Major surgical procedure (excluding placement of vascular access) or significant traumatic injury within 4 weeks of the first dose of study intervention or an anticipated need for major surgery during the study. Participants should have fully recovered from any clinically significant AEs.
As judged by the investigator, any other evidence of diseases (such as severe or uncontrolled systemic diseases or active uncontrolled infections, including but not limited to uncontrolled major seizure disorder, active bleeding diseases, superior vena cava syndrome, or history of allogenic organ transplant, which, in the investigator’s opinion, makes it undesirable for the participant to participate in the study or would jeopardise compliance with the protocol.