Atossa to Showcase 16–26% ER Inhibition and EVANGELINE 40 mg Phase 2 Trial
ATOS•Two ASCO abstracts show (Z)-endoxifen achieved 16–26% of control ER activity and under 5% in ESR1 wild-type models with consistent inhibition across key ESR1 mutations. Its EVANGELINE Phase 2 neoadjuvant trial in premenopausal ER+/HER2- patients uses 40 mg daily plus goserelin, targeting ≥65% achieving Ki-67 ≤10% at four weeks.
1. Preclinical Data Abstract
Atossa’s ASCO 2026 abstract presents new preclinical results showing (Z)-endoxifen achieved dose-dependent ER signaling inhibition to 16–26% of control in parental models and under 5% in ESR1 wild-type models (p<0.001), while maintaining consistent inhibition across Y537N, Y537S and D538G mutations (p<0.01).
2. EVANGELINE Phase 2 Trial
The EVANGELINE study (NCT05607004) is an open-label, multicenter Phase 2 trial evaluating daily 40 mg (Z)-endoxifen plus goserelin as neoadjuvant therapy in premenopausal women with ER+/HER2-, cT2-3, cN0-1 breast cancer, using a Simon two-stage design to assess whether ≥65% of patients achieve Ki-67 ≤10% after four weeks, with additional cohorts measuring ORR and safety.
