SERENA-6 interpretation and clinical implications: intercepting endocrine resistance in metastatic breast cancer

In patients treated with first-line AI plus CDK4/6 inhibitor, SERENA-6 showed the benefit of switching from an aromatase inhibitor to the oral SERD camizestrant upon detection of an emerging ESR1 mutation, before disease progression. While this adaptive oncology approach has shown key benefits for patients, the integration of emerging ctDNA targets into treatment decisions has been questioned. Here, we provide further clarification on several aspects of this clinically relevant discussion.