BERLIN — Enhertu has become a staple treatment in advanced breast cancer, but new data presented Saturday at the European Society for Medical Oncology’s annual conference show the drug can have powerful benefits for patients when given earlier in the disease, opening the door to higher rates of cures.

For Enhertu’s makers, AstraZeneca and Daiichi Sankyo, the findings from the two trials could expand the drug, already a blockbuster, to tens of thousands of additional patients. The results also reflect how drugs like Enhertu — what are known as antibody-drug conjugates, or ADCs — are increasingly moving beyond late-stage and metastatic cancers, upending traditional chemotherapy regimens.

“It has been clawing its way up the ladder,” said Harold Burstein, a breast oncologist at Dana-Farber

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