Atossa Therapeutics FY Conference Summary Company Overview - **Company**: Atossa Therapeutics (NasdaqCM: ATOS) - **Lead Asset**: Zinhoxifen, a novel drug for breast cancer treatment Key Points Product Differentiation - Zinhoxifen is a pure form of (Z)-endoxifen, which is derived from tamoxifen, offering efficacy with fewer side effects [2][5] - It has unique properties: it blocks estrogen receptor interaction and stimulates receptor degradation, unlike other drugs that only block [2][3] - Higher doses of Zinhoxifen activate a different apoptotic pathway (PKC beta), enhancing its cancer-fighting capabilities [3] Clinical Trial Insights - Clinical trials involving approximately 700 women showed a reduced incidence of vasomotor symptoms (e.g., hot flashes) compared to tamoxifen [5][6] - Higher levels of (Z)-endoxifen correlated with fewer hot flashes, indicating a potentially better safety profile [6] - Zinhoxifen is being explored for both prevention (1-4 mg) and treatment of metastatic breast cancer (20-80 mg) [7][8] Metastatic Breast Cancer - Initial data from trials at the National Cancer Institute and Mayo Clinic indicated a 25% clinical response rate and 50% partial response rate in patients resistant to current therapies [9] - The iSpy 2 trial is underway, combining Zinhoxifen with the CDK4/6 inhibitor abemaciclib, showing promising recruitment [11][12] Regulatory and Development Plans - Atossa is preparing for an IND filing under the FDA's Project Optimus, focusing on optimal dosing strategies [14][20] - The iSpy 2 trial aims to assess biological activity and tumor shrinkage in high-risk breast cancer patients [21] Market Opportunity - Approximately 1.7 million women currently take tamoxifen, indicating a significant market for Zinhoxifen, especially due to its better tolerance [27] - Pricing strategies suggest that Zinhoxifen could be positioned between $6,000 to $20,000 per year for prevention, contrasting with higher costs for metastatic treatments [28] Upcoming Milestones - Key upcoming events include data from the low-dose program in December and the initiation of the high-dose Project Optimus trial [29] Additional Insights - The FDA's recent requirement for mammogram results to include breast density information may increase awareness and demand for preventive treatments like Zinhoxifen [24][25] - The potential for Zinhoxifen to reduce side effects associated with current therapies could enhance patient compliance and market acceptance [26] This summary encapsulates the critical aspects of Atossa Therapeutics' conference, highlighting the innovative approach of Zinhoxifen in breast cancer treatment and the company's strategic direction in clinical development and market positioning.

Core Viewpoint - Atossa Therapeutics is actively engaging with investors and the biotech community to discuss its clinical advancements and future milestones, particularly focusing on its lead product candidate, (Z)-endoxifen, which aims to innovate breast cancer treatment and prevention [1][3]. Group 1: Company Overview - Atossa Therapeutics, Inc. is a clinical-stage biopharmaceutical company dedicated to transforming breast cancer treatment and prevention through innovative science and patient-focused solutions [6]. - The company's lead product candidate, (Z)-endoxifen, is being developed as a therapy across the breast cancer spectrum, including both prevention and treatment settings [6]. Group 2: Upcoming Events - Dr. Steven Quay, Chairman and CEO of Atossa, will participate in a fireside chat at the H.C. Wainwright 27th Annual Global Investment Conference on September 8, 2025, at 3:00 p.m. ET [1][3]. - The live presentation will be webcast, with a replay available for approximately 90 days on the company's investor website [4]. Group 3: Clinical Progress - Dr. Quay will provide updates on the clinical progress of (Z)-endoxifen, highlighting its dual mechanisms of action as a Selective Estrogen Receptor Modulator (SERM) that may offer a differentiated solution for breast cancer prevention and treatment [3]. - Recent feedback from regulatory advisors has been encouraging, which could potentially accelerate the company's development path [3].

Core Insights - Atossa Therapeutics is advancing (Z)-endoxifen into a pivotal Phase 2 dose-ranging study for metastatic breast cancer, with regulatory input from the FDA and an IND filing expected in Q4 2025, aiming for topline results in 2026 [1][3][4] Study Design and Execution - The global Phase 2 study will evaluate the safety, pharmacokinetics, pharmacodynamics, and preliminary anti-tumor activity of (Z)-endoxifen monotherapy [3][4] - PSI has been selected as the contract research organization to manage the study, recognized for its efficiency in oncology trials, with 93% of its studies enrolling on time in 2024 [4][5][6] Market Opportunity - Approximately 5.6% of newly diagnosed invasive breast cancers in the U.S. are metastatic, equating to about 13,000 women annually, with an estimated 170,000 women currently living with metastatic breast cancer [7] - Current therapies often fail due to resistance, creating a significant market opportunity for (Z)-endoxifen as a potential first-in-class therapy in this multi-billion-dollar market [7] Pipeline Development - In addition to the metastatic trial, Atossa is advancing other Phase 2 studies, including (Z)-endoxifen monotherapy in early-stage breast cancer and combination therapy with abemaciclib [8] Product Profile - (Z)-endoxifen is a potent Selective Estrogen Receptor Modulator/Degrader (SERM/D) with dual mechanisms of action, showing potential for superior bone protection and a favorable safety profile compared to tamoxifen [9][10] - The proprietary formulation of (Z)-endoxifen is designed to enhance bioavailability and overcome limitations of previous formulations [10]

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2025 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from XXXXXXXX XX, XXXX to XXXXXXXX XX, XXXX Commission File Number: 001-35610 ATOSSA THERAPEUTICS, INC. (Address of principal executive offices) (Zip Code) Registrant ...

FDA Provides Positive Feedback, Clears Path for Atossa to File IND for (Z)-Endoxifen in Metastatic Breast Cancer; FDA Indicates No Additional Toxicity Studies Required Exhibit 99.1 Atossa Therapeutics Announces Second Quarter 2025 Financial Results and Provides a Corporate Update Strong I-SPY2 Results Reinforce Ef icacy of Atossa's Monotherapy at 3-weeks SEATTLE, August 12, 2025 — Atossa Therapeutics, Inc. (Nasdaq: ATOS) (Atossa or the Company), a clinical-stage biopharmaceutical company developing innovati ...

FDA Provides Positive Feedback, Clears Path for Atossa to File IND for (Z)-Endoxifen in Metastatic Breast Cancer; FDA Indicates No Additional Toxicity Studies Required Strong I-SPY2 Results Reinforce Efficacy of Atossa's Monotherapy at 3-weeks SEATTLE, Aug. 12, 2025 /PRNewswire/ -- Atossa Therapeutics, Inc. (Nasdaq: ATOS) (Atossa or the Company), a clinical-stage biopharmaceutical company developing innovative medicines for breast cancer, today announced its financial results for the second quarter ended Ju ...

Core Viewpoint - Atossa Therapeutics has received positive feedback from the FDA regarding its proposed dose optimization trial for (Z)-endoxifen, aimed at treating ER+/HER2- metastatic breast cancer, which is a significant milestone for the company [1][2][3] FDA Feedback and Clinical Development - The FDA's constructive responses affirm key elements of Atossa's clinical development plan, eliminating the need for a virtual pre-IND meeting and facilitating a potential IND submission by Q4 2025 [2][3] - The FDA supports Atossa's dose optimization strategy and agrees with the existing nonclinical data package, enhancing confidence in the company's regulatory approach [3][7] Dose Optimization Strategy - The FDA has confirmed that existing clinical and nonclinical data are sufficient to initiate Part A (monotherapy) of the proposed dose optimization study, providing guidance on study design enhancements [7] - Atossa plans to explore multiple dose levels in its upcoming clinical study to define the optimal dose for combination therapy, aligning with the FDA's Project Optimus initiative [6][7] Combination Study Support - The FDA agrees with the scientific rationale for combining (Z)-endoxifen with standard-of-care therapies for breast cancer, which helps narrow the strategic approach for the potential IND [7] Cardiac Safety and Nonclinical Data - The FDA has confirmed that Atossa's cardiac safety assessment plan, including ECGs and QT interval monitoring, is sufficient for the monotherapy portion of the trial [7] - The existing nonclinical safety data package is deemed adequate, allowing Atossa to proceed without additional toxicity studies [7] Next Steps and Strategic Momentum - Atossa will announce plans for the target patient population, combination backbone, and overall trial design for the upcoming dose-ranging study in the coming weeks [7] - The company is positioned to maintain strategic momentum and meet regulatory milestones, aiming to deliver (Z)-endoxifen to patients and enhance shareholder value [5][10] About (Z)-Endoxifen - (Z)-endoxifen is a potent Selective Estrogen Receptor Modulator (SERM) that inhibits and potentially degrades estrogen receptors, showing activity in tumors resistant to other therapies [8][10] - Atossa is developing an oral formulation of (Z)-endoxifen that is enteric-coated to ensure optimal bioavailability and therapeutic integrity [9] Clinical Trials and Intellectual Property - Atossa is prioritizing (Z)-endoxifen for metastatic breast cancer, currently evaluating it in three Phase 2 trials [10] - The program is supported by a growing global intellectual property portfolio, including recently issued U.S. patents [10]

Core Viewpoint - Atossa Therapeutics has received positive feedback from the FDA regarding its proposed dose optimization trial for (Z)-endoxifen, aimed at treating ER+/HER2- metastatic breast cancer, which is a significant milestone for the company [1][2][3] FDA Feedback and Clinical Development - The FDA's constructive responses affirm key elements of Atossa's clinical development plan, eliminating the need for a virtual pre-IND meeting and facilitating a potential IND submission by Q4 2025 [2][3] - The FDA supports Atossa's dose optimization strategy and agrees with the existing clinical and nonclinical data, allowing the initiation of Part A (monotherapy) of the proposed study [7] Strategic Momentum and Future Plans - Atossa is positioned to maintain strategic momentum and meet regulatory milestones, aiming to deliver (Z)-endoxifen to patients and enhance shareholder value [5] - The company plans to announce details regarding the target patient population, combination therapies, and overall trial design for the upcoming dose-ranging study in the coming weeks [7] Project Optimus and Dose Exploration - The FDA's Project Optimus initiative emphasizes data-driven dose exploration to maximize benefits and minimize toxicity, which aligns with Atossa's upcoming clinical study plans [6] - Atossa will explore multiple dose levels in its study to define the optimal dose for combination therapy while ensuring a balance between efficacy and patient safety [6] (Z)-Endoxifen Overview - (Z)-endoxifen is a potent Selective Estrogen Receptor Modulator (SERM) that inhibits and potentially degrades estrogen receptors, showing activity in tumors resistant to other therapies [8] - The compound is being developed in a proprietary oral formulation that is enteric-coated to ensure optimal bioavailability and therapeutic integrity [9] Clinical Trials and Intellectual Property - Atossa is prioritizing (Z)-endoxifen for metastatic breast cancer, currently evaluating it in three Phase 2 trials [10] - The program is supported by a growing global intellectual property portfolio, including recently issued U.S. patents and pending applications worldwide [10]

(Z)-endoxifen's Potential & Differentiation - (Z)-endoxifen is a novel, next-generation anti-estrogen with best-in-class potential across the breast cancer treatment paradigm[8] - (Z)-endoxifen is potentially a superior ER antagonist, being 100-fold more potent vs other SERMs, and demonstrates superior antitumor efficacy in preclinical and clinical studies[7] - (Z)-endoxifen inhibits clinically relevant ESR1 mutants, an acquired resistance mechanism to aromatase inhibitors[7] - (Z)-endoxifen has the potential to avoid current negative "on target off tissue" effects, potentially improving safety & tolerability and adherence[7] Clinical Trial Results & Regulatory Path - In a Phase II trial, CDK4/6 inhibitor-naïve patients had improved Progression-Free Survival (PFS) with (Z)-endoxifen compared to tamoxifen, with median PFS of 7.2 months versus 2.4 months, HR=0.42 (95% CI 0.22-0.80), Log rank test P=0.002[12] - The KARISMA trial showed a 17.3 percentage point reduction (p<0.01) in mammographic breast density with 1 mg of (Z)-endoxifen compared to a minimal change in the placebo group of 0.27 percentage points[13] - In an ongoing neoadjuvant clinical study, (Z)-endoxifen has demonstrated promising early efficacy with 1 CR and multiple PRs[14] Financials - The company's research and development expenses were $14.117 million in 2024, compared to $17.334 million in 2023[21] - The company's general and administrative expenses were $13.504 million in 2024, compared to $14.043 million in 2023[21] - The company's net loss was $(25.504) million in 2024, compared to $(30.094) million in 2023[21]

Atossa Therapeutics Conference Summary Company Overview - Atossa Therapeutics (NASDAQ: ATOS) focuses on breast cancer and oncology, addressing a multi-billion dollar opportunity in estrogen receptor positive breast cancer with its lead molecule, Z endoxifen [3][52]. Key Points and Arguments - **Market Opportunity**: Atossa is targeting a significant market in estrogen receptor positive breast cancer, with Z endoxifen showing potential from prevention to metastatic treatment [3][52]. - **Intellectual Property**: The company boasts a robust and growing intellectual property portfolio, with 92 patents held by the CEO, indicating strong future value for shareholders [4][52]. - **Financial Position**: Atossa is in a strong financial position, with over $65 million in cash as of March 31, providing approximately two years of operational runway and no debt [5][50][51]. - **Leadership Team**: The company has an experienced leadership team and advisory group, including experts from renowned institutions like the Mayo Clinic and UCSF [6][52]. Product Differentiation - **Z endoxifen's Unique Properties**: - It has superior estrogen receptor antagonism, which is crucial as 75% of breast cancers are driven by estrogen receptors [16][52]. - It triggers apoptosis, a unique mechanism that differentiates it from other endocrine therapies [10][18][52]. - Improved adherence due to a favorable side effect profile compared to existing treatments like tamoxifen and aromatase inhibitors [11][20][52]. Clinical Insights - **Unmet Needs**: Approximately 40-50% of patients stop taking current treatments due to adverse events, highlighting the need for better-tolerated therapies [7][8][52]. - **Efficacy Data**: Clinical trials have shown significant reductions in tumor size and improved patient outcomes with Z endoxifen compared to traditional therapies [33][45][52]. - **Combination Therapies**: Ongoing research indicates that Z endoxifen may work synergistically with CDK4/6 inhibitors, enhancing treatment efficacy [21][36][52]. Regulatory Strategy - **FDA Engagement**: Atossa is actively engaging with the FDA to expedite the approval process for Z endoxifen, focusing on the metastatic setting as the first target for approval [29][48][52]. - **Upcoming Trials**: The company aims to initiate its first patient in an FDA-approved registration trial by the end of 2025, with ongoing trials in prevention and neoadjuvant settings [50][52]. Conclusion - Atossa Therapeutics is positioned strongly within the breast cancer treatment landscape, with a promising drug candidate, a solid financial foundation, and a strategic approach to regulatory approval and market entry [52].