This study is designed as a randomized, active-controlled, superiority study in patients with unresectable locally advanced or metastatic HER2-positive breast cancer. The patients should have had either progression during or after at least two HER2-targeting treatment regimens for locally advanced or metastatic disease or progression during or after (ado-)trastuzumab emtansine treatment.
Eligible patients will be randomly assigned (2:1) to receive SYD985 or physician's choice treatment until disease progression, unacceptable toxicity or study termination by the Sponsor. During treatment, patients will have to visit the clinical site to assess efficacy, quality of life (QoL), and safety using standardized criteria.
