This phase II trial investigates how well trastuzumab deruxtecan works alone or in combination with anastrozole in treating patients with HER2 low, hormone receptor positive breast cancer. Trastuzumab deruxtecan is a monoclonal antibody, called trastuzumab, linked to a chemotherapy drug called deruxtecan. Trastuzumab attaches to HER2 expressed at low levels on cancer cells in a targeted way and delivers deruxtecan to kill them. Anastrozole works by decreasing estrogen production and suppressing the growth of tumors that need estrogen to grow. This study is evaluating how effective trastuzumab deruxtecan is at treating hormone receptor positive cancer cells that have low levels of HER2 expressed on them when given alone or in combination with anastrozole.
Previously untreated operable invasive carcinoma of the breast greater than 2.0 cm (cT2) in size based on physical exam or imaging. Patients with clinical node negative disease or clinical node (cN1/cN2) positive are allowed provided they are deemed to have operable disease at study entry
Participants with clinically involved lymph nodes should not have radiological evidence of distant disease per standard of care staging prior to patient informed consent form (PICF) signature
In the United States
Tumor is HER2-low by immunohistochemistry (IHC), defined as 1+ or 2+, confirmed by central testing (central testing results not required for enrollment, unless no local results available). If HER2 is 2+ by IHC, fluorescence in situ hybridization (FISH) must be performed (per standard of care) and the FISH result must be HER2 non-amplified per 2018 American Society of Clinical Oncology College of American Pathologists (ASCO CAP) guidelines
Recurrent or metastatic breast cancer
Bilateral breast cancer (multifocal or multicentric breast cancer is allowed provided that all biopsied lesions are HER2 1+ or 2+, not FISH amplified and are HR positive per ASCO guidelines)
Inflammatory breast cancer
Prior systemic therapy for invasive cancer
Jonsson Comprehensive Cancer Center
Lead sponsor
Translational Research in Oncology-U.S
Collaborator
Daiichi Sankyo Co., Ltd.
Collaborator