Atossa Therapeutics Partners with PSI for Pivotal Breast Cancer Study

Atossa Therapeutics selects PSI as CRO for pivotal Phase 2 study of (Z)-endoxifen in metastatic breast cancer. Patient enrollment expected to begin in Q4 2025, with topline data in 2026. The market opportunity includes approximately 170,000 women living with metastatic breast cancer in the U.S. PSI's expertise in oncology trials is anticipated to expedite the clinical timeline and potentially accelerate the path to market for (Z)-endoxifen.

Atossa Therapeutics, Inc. (Nasdaq: ATOS) has selected PSI, a leading global contract research organization (CRO), to operationalize and manage its planned Phase 2 dose-ranging study of (Z)-endoxifen in women with metastatic breast cancer (mBC). The study, designed with input from the U.S. Food and Drug Administration (FDA), aims to evaluate the safety, pharmacokinetics, pharmacodynamics, and preliminary anti-tumor activity of (Z)-endoxifen as a monotherapy [1].

Patient enrollment for the study is expected to commence following the Investigational New Drug (IND) filing in the fourth quarter of 2025, with topline results anticipated in 2026. The successful completion of this study positions Atossa to transition into Phase 3 development, a crucial step towards regulatory approval and market entry [1].

PSI, renowned for its expertise in oncology trials, is expected to expedite the clinical timeline and potentially accelerate the path to market for (Z)-endoxifen. The CRO's ability to deliver regulatory-grade data, achieve on-time enrollment, and seamlessly scale programs into Phase 3 trials underscores its suitability for this pivotal study [1].

The market opportunity for (Z)-endoxifen is substantial, with approximately 170,000 women living with metastatic breast cancer in the United States. Current therapies often fail due to resistance, leaving patients with limited treatment options. (Z)-endoxifen, a highly potent Selective Estrogen Receptor Modulator/Degrader (SERM/D), has demonstrated clinical activity in tumors resistant to existing endocrine therapies, positioning it as a potential first-in-class therapy in this multi-billion-dollar market [1].

Atossa is also advancing additional Phase 2 studies in the ER+/HER2- neoadjuvant breast cancer setting, including studies of monotherapy and combination therapy with abemaciclib. Multiple clinical readouts are anticipated in the coming months [1].

References:
[1] https://www.prnewswire.com/news-releases/atossa-therapeutics-selects-psi-as-contract-research-organization-for-pivotal-dose-ranging-study-of-z-endoxifen-in-metastatic-breast-cancer-302534234.html