Roche's Giredestrant Fails Primary Endpoint in Phase 3 Breast Cancer Trial

Roche's investigational drug giredestrant combined with Pfizer's Ibrance (palbociclib) failed to show statistically significant improvement in progression-free survival compared to standard hormonal therapy (letrozole plus palbociclib) in the phase 3 persevERA trial for first-line treatment of advanced ER-positive, HER2-negative breast cancer.1 2 3 5

The trial showed a numerical improvement in progression-free survival, and the combination was well tolerated with adverse events consistent with known profiles.2 3 5

Roche shares dropped over 5% (up to 8% intraday) following the announcement on March 9, 2026.1 4 6

This is the first of two phase 3 first-line trials; results from the second (pionERA) are expected in 2027.2 3 5 6

Giredestrant, an oral SERD, targets estrogen-driven breast cancers (up to 80% of cases) and has shown promise in earlier trials like evERA and lidERA for adjuvant and other settings; FDA accepted NDA based on evERA with decision December 18.1 4 5 6