Dr Mabel Mardones speaks to ecancer about the primary analysis of the phase III persevERA BC trial.
In first-line treatment of ER-positive, HER2-negative locally advanced or metastatic breast cancer (LA/mBC), CDK4/6 inhibitors combined with endocrine therapy remain the standard of care.

Giredestrant, a next-generation oral selective oestrogen receptor degrader, has shown promising efficacy in earlier settings, prompting evaluation in combination with palbociclib versus letrozole plus palbociclib in the phase 3 persevERA BC trial.

Results showed a numerical improvement in progression-free survival with giredestrant plus palbociclib compared to letrozole plus palbociclib, with a median benefit of 4.9 months. However, this difference did not reach statistical significance.

The safety profile was consistent with known effects of CDK4/6 inhibition, with haematologic toxicities being the most common high-grade adverse events. Treatment discontinuation rates due to adverse events were low and similar between groups.

Dr Mardones says that overall, while giredestrant demonstrated modest clinical activity, it did not significantly improve outcomes over standard endocrine therapy in this setting.