Atossa Therapeutics Announces Acceptance of Four Abstracts Highlighting (Z)-Endoxifen Research for Presentation at the 2025 San Antonio Breast Cancer Symposium

Rhea-AI Summary

Atossa Therapeutics (Nasdaq: ATOS) announced four abstracts featuring (Z)-endoxifen research were accepted for presentation at the 2025 San Antonio Breast Cancer Symposium (SABCS), Dec 9-12, 2025 in San Antonio, TX. The company will present four posters on Dec 11-12 covering DCIS management, a low-dose I-SPY2 endocrine pilot, ESR1 mutant activity, and a Phase 2 neoadjuvant EVANGELINE trial.

Presentations include scheduled poster sessions on Dec 11 (12:30pm–2:00pm CT) and Dec 12 (7:00am–8:30am CT and 12:30pm–2:00pm CT).

Insights

Clinical development strategist

Four SABCS poster acceptances increase visibility for (Z)-endoxifen but provide no new clinical outcomes yet.

Atossa Therapeutics secured four poster presentations at the San Antonio Breast Cancer Symposium on December 9-12, 2025, covering RECAST DCIS, an I-SPY2 endocrine optimization pilot, mechanistic data on ESR1 mutants, and the randomized Phase 2 EVANGELINE non-inferiority trial comparing (Z)-endoxifen + goserelin versus exemestane + goserelin.

The business mechanism is straightforward: scientific presentations raise awareness among clinicians and researchers and can accelerate external scrutiny and collaboration. These listings do not report efficacy or safety results in this notice, so the clinical and commercial implications remain undefined.

Key dependencies and risks include the actual data content and statistical strength presented at the sessions, regulatory interpretation of any positive endpoints, and how the Phase 2 EVANGELINE outcomes compare on prespecified non-inferiority margins. Watch the poster sessions on December 11, 2025 and December 12, 2025 for concrete efficacy, safety, and biomarker readouts within the next week of the symposium.

Studies highlight findings in the use of (Z)-endoxifen to advance breast cancer treatment and prevention

SEATTLE, Nov. 6, 2025 /PRNewswire/ -- Atossa Therapeutics, Inc. (Nasdaq: ATOS) ("Atossa" or the "Company"), a clinical-stage biopharmaceutical company developing innovative medicines in oncology, announces that four abstracts featuring data on (Z)-endoxifen have been accepted for presentation at the San Antonio Breast Cancer Symposium (SABCS), being held on December 9-12, 2025, in San Antonio, TX.

"We continue to add to our body of clinical evidence. At SABCS 2025, we look forward to four poster presentations highlighting findings from studies evaluating the use of (Z)-endoxifen to advance breast cancer treatment and prevention," said Dr. Steven Quay, Atossa Therapeutics President and Chief Executive Officer.

Poster Presentation Details:
Title:	Initial results from RECAST DCIS: Multicenter platform trial testing active surveillance and novel endocrine therapy agents for DCIS management
Date/Time:	Thursday, December 11, 2025, 12:30pm - 2:00pm CT
Title:	Low dose (Z)-endoxifen in the I-SPY2 Endocrine Optimization Pilot
Date/Time:	Thursday, December 11, 2025, 12:30pm - 2:00pm CT
Title:	(Z)-Endoxifen Maintains ERα Antagonist Function Against ESR1 Mutants via Inactive Conformation Stabilization and Reversal of Mutant ESR1-Associated Transcriptional Signatures
Date/Time:	Friday, December 12, 2025, 7:00am - 8:30am CT
Title:	A Randomized Phase 2 Non-Inferiority Trial of (Z)-Endoxifen + Goserelin vs Exemestane + Goserelin as Neoadjuvant Treatment for Premenopausal Women with ER+/HER2- Breast Cancer (EVANGELINE)
Date/Time:	Friday, December 12, 2025, 12:30pm - 2:00pm CT

 

About Atossa Therapeutics

Atossa Therapeutics, Inc. (Nasdaq: ATOS) is a clinical-stage biopharmaceutical company developing innovative therapies for significant unmet needs in breast cancer. Atossa's strategy emphasizes disciplined capital allocation, focusing resources on programs and data packages that can enable future regulatory submissions and potential commercialization. For more information, visit www.atossatherapeutics.com and refer to Atossa's filings with the U.S. Securities and Exchange Commission (SEC).

Forward-Looking Statements
This press release contains forward-looking statements, including statements regarding Atossa's commercial readiness, financing strategy, operational plans, and the development and potential commercialization of (Z)-endoxifen. These statements are subject to risks and uncertainties that could cause actual results to differ materially, including market conditions, regulatory outcomes, clinical results, manufacturing and supply, intellectual-property challenges, and the Company's ability to secure sufficient funding on acceptable terms. For a discussion of risks and uncertainties, please refer to Atossa's filings with the U.S. Securities and Exchange Commission. Atossa undertakes no obligation to update forward-looking statements, except as required by law.

 

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SOURCE Atossa Therapeutics Inc

FAQ

What is Atossa (ATOS) presenting at SABCS 2025 and when?

Atossa (ATOS) will present four (Z)-endoxifen posters at SABCS 2025 on Dec 11–12, 2025, including sessions at 12:30pm–2:00pm CT and 7:00am–8:30am CT.

Which (Z)-endoxifen studies will ATOS present at the Dec 11, 2025 poster session?

On Dec 11, 2025 (12:30pm–2:00pm CT) ATOS will present: the RECAST DCIS initial results and the low-dose (Z)-endoxifen I-SPY2 endocrine optimization pilot.

What are the topics of ATOS's Dec 12, 2025 SABCS presentations?

On Dec 12, 2025 ATOS will present an abstract on (Z)-endoxifen activity against ESR1 mutants (7:00am–8:30am CT) and the EVANGELINE Phase 2 neoadjuvant randomized trial (12:30pm–2:00pm CT).

Does the SABCS schedule for ATOS include clinical trial data for (Z)-endoxifen?

Yes. Scheduled posters include clinical study results from RECAST DCIS, an I-SPY2 pilot, ESR1 mutant analyses, and the randomized Phase 2 EVANGELINE trial.

How can investors follow ATOS presentations at SABCS 2025?

Investors can note the poster titles and scheduled session times (Dec 11–12, 2025) and check SABCS event listings or Atossa investor communications for access details.

What is the significance of ATOS presenting four abstracts on (Z)-endoxifen at SABCS 2025?

Multiple accepted abstracts indicate ongoing clinical and translational work on (Z)-endoxifen across DCIS management, endocrine optimization, ESR1 biology, and a Phase 2 neoadjuvant trial.