Drug combination delays advanced breast cancer progression in international trial

An experimental drug combination has delayed the worsening of advanced, estrogen-sensitive breast cancer in an international trial involving 373 patients across 13 countries.

The phase 3 evERA study tested giredestrant plus everolimus against standard hormone therapy plus everolimus. Participants had ER-positive, HER2-negative cancer that had progressed after hormone therapy and a targeted medicine called a CDK4/6 inhibitor, a setting where treatment options are limited.

Across the trial, median progression-free survival, meaning how long patients remained alive without their cancer worsening, was 8.8 months with the experimental combination, compared with 5.5 months in the comparison group. For patients whose tumors carried an ESR1 mutation, which can contribute to resistance to hormone treatment, the corresponding figures were 10 months and 5.5 months. Both improvements were statistically significant.

Giredestrant is taken by mouth and is designed to break down the estrogen receptors that help fuel these cancers. The Roche-funded study was published in the New England Journal of Medicine.

Side effects were common in both groups, with similar overall rates. They included mouth sores, diarrhea and anemia. Giredestrant remains experimental, and longer follow-up is needed to establish whether the combination also helps patients live longer overall.