Atossa selects PSI for Z-endoxifen monotherapy study

Atossa Therapeutics (ATOS) announced it has selected PSI, a leading global contract research organization, or CRO, to operationalize and manage its planned Z-endoxifen monotherapy dose-ranging study in women with metastatic breast cancer, or mBC. The study was designed following guidance from the FDA and is intended to directly inform a subsequent Phase 3 trial. The global Phase 2, multi-center dose-ranging study is designed to evaluate Z-endoxifen monotherapy for safety, pharmacokinetics/pharmacodynamics, and preliminary anti-tumor activity. Patient enrollment is expected to follow the Investigational New Drug filing in Q4 2025, with topline data anticipated in 2026. In addition to the upcoming metastatic dose-ranging trial, Atossa is advancing additional Phase 2 studies in the ER+/HER2- neoadjuvant breast cancer setting, including studies of monotherapy of Z-endoxifen in early stage breast cancer; combination therapy with abemaciclib in women with early stage breast cancer at high risk of recurrence; and monotherapy in women with a biopsy-proven diagnosis of ductal carcinoma in situ (DCIS). Multiple clinical readouts are anticipated in the coming months.