Atossa Therapeutics Presents Data from 40mg Cohort of Phase 2 EVANGELINE Clinical Trial Showing 100% Disease Control Rate After 24-Weeks of Treatment with (Z)-Endoxifen

SEATTLE, April 09, 2024 (GLOBE NEWSWIRE) -- Atossa Therapeutics, Inc. (Nasdaq: ATOS) (“Atossa” or the “Company”) today announced promising safety and efficacy data from the Company’s Phase 2 EVANGELINE (Endoxifen Versus exemestANe GosEreLIn) clinical trial. The EVANGELINE study is evaluating (Z)-endoxifen as a neoadjuvant treatment for pre-menopausal women with Grade 1 or 2 Estrogen Receptor positive (ER+) / Human Epidermal Growth Factor Receptor 2 negative (HER2-) breast cancer. Atossa is a clinical stage biopharmaceutical company developing innovative medicines in areas of significant unmet medical need in oncology with a focus on breast cancer.

The data, which is being presented at the American Association for Cancer Research (AACR) Annual Meeting, is from the 40mg pharmacokinetic (PK) run-in cohort of the study. Seven women were enrolled in the cohort and treated daily for 28 days. At 28 days, six of the seven had Ki-67 levels below 10% and stayed on treatment for an additional five months. Per the study protocol, the seventh patient, whose Ki-67 decreased 19% but stayed above 10%, discontinued treatment and had surgery.

Among the six patients who were treated for a total of 24-weeks, magnetic resonance imaging (MRI) central review demonstrated target lesion decreases in all patients with one complete response (CR), one partial response (PR) and four stable disease (SD), per Response Evaluation Criteria In Solid Tumors (RECIST) criteria. The average target lesion decrease was 32% at 12 weeks and 37% at 24 weeks with all patients experiencing at least a 15% reduction in target lesion at 24-weeks.

Ki-67 for the 40mg cohort patients was reduced from an average of 14.5% at screening to 5.3% at 28 days and 1.2% at 24-weeks. This represents a reduction of 63% at 28 days and 92% at 24 weeks. Ki-67 is a cellular marker for proliferation and indicates how fast the tumor is growing. Less than 10% is considered low and associated with better surgical outcomes and a lower incidence of recurrence.

Treatment related toxicities included grade 3 headache (one patient), grade 2 amenorrhea (one patient), and grade 2 hot flashes (one patient). There were no grade 4 or 5 treatment related toxicities.

"The EVANGELINE study introduces a promising neoadjuvant approach for premenopausal women with ER+/HER2- breast cancer, exploring a potential treatment option that could improve clinical outcomes without the need for ovarian function suppression,” said Nusayba A. Bagegni, MD, Associate Professor of Medicine, Division of Oncology, Washington University School of Medicine and EVANGELINE study investigator. “The data thus far, which shows (Z)-endoxifen is beneficial and well tolerated, suggests that this treatment could potentially help address a significant unmet need in this patient population.”