280P Intracranial activity of trastuzumab-deruxtecan (T-DXd) in HER2-positive breast cancer patients with active brain metastases: Results from the first stage of the phase II TUXEDO-1 trial

Brain metastases (BM) are frequently diagnosed in HER2-positive breast cancer (BC) and add to morbidity and mortality. Trastuzumab deruxtecan (T-DXd) is a novel antibody-drug conjugate approved for the treatment of HER2-positive metastatic BC but has not been specifically investigated in the context of BM. Here, we present preliminary results of the prospective, single-centre, single-arm, phase II TUXEDO-1 trial investigating T-DXd in HER2-positive BC patients (pts) with active BM.