Saruparib (AZD5305) Plus Camizestrant or Plus Endocrine Therapy, Compared With CDK4/6 Inhibitor Plus Endocrine Therapy or Plus Camizestrant in HR-Positive, HER2-Negative (IHC 0, 1+, 2+/ ISH Non-amplified), BRCA1, BRCA2, or PALB2m Advanced Breast Cancer

Approximately 4680 participants will be screened to achieve approximately 788 participants randomised to study intervention. Participants will be randomised in a 2:2:1:2 ratio to one of the following intervention groups: * Arm 1: saruparib (AZD5305) plus camizestrant * Arm 2: Physician's choice CDK4/6i plus physician's choice ET * Arm 3: Physician's choice CDK4/6i plus camizestrant * Arm 4: Saruparib (AZD5305) plus physician's choice ET Treatment continues until BICR-confirmed disease progression, unacceptable toxicity occurs, or the participant withdraws consent.