INNV-02. MULTIFOCAL, DURABLE AND PATHOLOGICALLY-CONFIRMED BRAIN METASTASIS COMPLETE RESPONSE TO TRASTUZUMAB DERUXTECAN

Abstract Antibody-based conjugates (ADCs) have transformed the treatment of Her2+ breast and other cancers. Unfortunately, CNS remains a sanctuary site for many such patients in part due to differential activity macromolecules across blood-brain tumor barriers. Trastuzumab deruxtecan (T-DXd), high-payload ADC, was recently found improve progression-free survival cancer compared with prior-generation trastuzumab emtansine, prompting us evaluate this agent woman CNS-only metastatic disease. T-DXd achieved complete response despite heavy pretreatment. Three persistent (and previously-irradiated) lesions were subsequently biopsy-proven represent effect. Response durable through 7 months treatment, subsequent recurrence setting holiday; partial observed drug rechallenge. Drug discontinuation ultimately required concern pulmonary toxicity. Our case suggests is active brain metastases supports further prospective evaluation randomized clinical trials.