This study will evaluate a structured sequential treatment strategy starting with T-DXd + pertuzumab upfront therapy, followed by an optimized maintenance therapy with dual HER2+blockade + CDK4/6i + ET and the opportunity to retreat with T-DXd once patients progress under maintenance aimed to maximizing disease control, optimizing tolerability, and preserving T-DXd as a future therapeutic option, while ensuring participant safety and regulatory compliance in participants with HER2+/HR+ advanced/metastatic breast cancer.
Sign and date the Main Trial informed consent form (ICF), prior to the start of any trial-specific procedures.
Participant must be ≥18 years of age at the time the ICF is signed.
Is locally advanced and unresectable or metastatic (participants who can be treated with curative intent are not eligible).
Participant must have histologically confirmed HER2+ and HR+ (ER+ and/or PR+), mBC. ER, PR, and HER2 measurements should be locally performed according to institutional guidelines.
Has prior therapy with any CDK inhibitor.
Previous T-DXd therapy for early BC with an EFS or disease-free interval of < 12 months from completion of T-DXd therapy in the neoadjuvant or post-neoadjuvant setting.
Is receiving concurrent therapy with other trial interventions (except pertuzumab which is part of Upfront Treatment and Maintenance Treatment).
Has prior therapy with any CDK inhibitor.
Daiichi Sankyo
Lead sponsor
AstraZeneca
Collaborator