AstraZeneca said its oral next-generation selective estrogen receptor degrader (SERD), camizestrant (Etcamah), missed the primary endpoint in the Phase III SERENA-4 study.
In 1,371 people with previously untreated ER-positive/HER2-negative advanced breast cancer, camizestrant plus Pfizer’s palbociclib (Ibrance) showed only a numerical—not statistically significant—improvement in progression-free survival versus anastrozole plus palbociclib.
The outcome is a setback for using camizestrant broadly as an upfront, first-line treatment in this population. AstraZeneca has not yet released the detailed efficacy data and plans a future scientific presentation.
The disappointment contrasts with the earlier SERENA-6 trial, where switching to camizestrant after an ESR1 mutation emerged during first-line endocrine therapy significantly improved progression-free survival. That suggests its potential may be more targeted than universal first-line use.
Reuters reported the result on September 11, 2026, shortly after the medicine had received U.S. approval in a different setting.
Sources:
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