A drug that delivers chemotherapy directly to tumors has shown impressive activity against some of the hardest-to-reach cancer cells: those that have spread to the brain in patients with advanced HER2-positive breast cancer. The findings, from an international clinical trial, reinforce earlier findings of the benefits of the drug — trastuzumab deruxtecan (T-DXd), an antibody-drug conjugate — in these patients, trial leaders say. 

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