Atossa Therapeutics to Present Pharmacokinetic and Tolerability Data from Phase 2 EVANGELINE Trial at the 2024 San Antonio Breast Cancer Symposium

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Atossa Therapeutics, Inc.
Atossa Therapeutics, Inc.

SEATTLE, Dec. 10, 2024 (GLOBE NEWSWIRE) -- Atossa Therapeutics, Inc. (Nasdaq: ATOS) (“Atossa” or the “Company”), a clinical stage biopharmaceutical company developing innovative medicines in areas of significant unmet medical need in oncology with a focus on breast cancer, today announced that three posters involving pharmacokinetic and tolerability data from the Phase 2 EVANGELINE trial will be presented at the 2024 San Antonio Breast Cancer Symposium (SABCS 2024). EVANGELINE is a randomized Phase 2 non-inferiority study investigating (Z)-endoxifen as a neoadjuvant treatment for premenopausal women with estrogen receptor-positive (ER+)/HER2-negative breast cancer.

The first poster, “Neoadjuvant Z-Endoxifen for Premenopausal Estrogen Receptor (ER)+, Human Epidermal Receptor (HER2)- Breast Cancer (BC): Evaluation of the Pharmacokinetic (PK) Run-in for the EVANGELINE Study,” discusses findings from the pharmacokinetic (PK) run-in phase of the trial. This phase evaluated (Z)-endoxifen monotherapy at 40 mg (data previously reported) and 80 mg (new data presented) doses, with and without goserelin (for ovarian function suppression or OFS). Findings include:

  • Primary Endpoint Achieved: 50 percent of patients (3/6) in the group that received 80 mg of (Z)-endoxifen with goserelin met the target steady-state plasma concentrations (Css) of 500–1000 ng/mL. Approximately 38 percent of patients (3/8) in the 80 mg/day (Z)-endoxifen only group reached target Css levels. The average plasma Css level for all patients receiving 80mg/day of (Z)-endoxifen was 484 ng/mL. As previously reported, no patients in the 40 mg/day (Z)-endoxifen arm reached the target plasma Css level of 500 ng/mL.

  • Tissue Penetration: Consistent with the recently updated trial protocol, tissue Css levels were evaluated in addition to plasma Css levels. The 80 mg/day dose, in both treatment arms, achieved tissue Css levels more than double that of plasma levels, surpassing the 500 ng/g target in 90 percent of patients—a level adequate to target PKCβ.

  • Antitumor Activity: Substantial tumor suppression was observed across all dosing levels, with or without ovarian function suppression (OFS). The 4-week Ki-67 ≤10 percent response rate was generally above 85 percent across dose levels, with or without the presence of OFS.

  • Safety and Tolerability: Overall, (Z)-endoxifen was well tolerated and target tissue Css levels were achieved without significant Grade 3–4 toxicities. Four gynecologic events were reported in the 80 mg groups, including one Grade 3 hemorrhagic cyst. These findings have informed protocol amendments to optimize dosing and tolerability.