AstraZeneca’s Etcamah worked when an ESR1 mutation appeared. Why did the broader first-line trial fail?
AstraZeneca has secured FDA accelerated approval for Etcamah after SERENA-6 showed that switching therapy when an ESR1 mutation emerged in circulating tumour DNA sharply delayed disease progression. Days later, however, the broader SERENA-4 first-line trial missed its primary endpoint, creating an unusually clear demonstration that patient selection and treatment timing may matter as much as