Atossa Therapeutics, Inc. (Atossa), a clinical-stage biopharmaceutical company, develops proprietary innovative medicines in areas of significant unmet medical need in oncology with a focus on women’s breast cancer and other breast conditions.
The company’s lead drug candidate under development is oral (Z)-endoxifen, which is being developed for both the prevention and treatment of breast cancer, and other therapeutic areas.
The company’s business strategy is to advance its programs through cl...
Atossa Therapeutics, Inc. (Atossa), a clinical-stage biopharmaceutical company, develops proprietary innovative medicines in areas of significant unmet medical need in oncology with a focus on women’s breast cancer and other breast conditions.
The company’s lead drug candidate under development is oral (Z)-endoxifen, which is being developed for both the prevention and treatment of breast cancer, and other therapeutic areas.
The company’s business strategy is to advance its programs through clinical studies, including potentially with partners, and opportunistically add programs in areas of high unmet medical need through acquisition, minority investment, collaboration, or internal development.
(Z)-endoxifen is an active metabolite of tamoxifen, which is an FDA-approved drug to treat and prevent breast cancer. Up to 50% of breast cancer survivors who take tamoxifen do not achieve therapeutic (Z)-endoxifen levels (meaning they are ‘refractory’) for a number of reasons, including that they, due to their genotype, do not have the requisite liver enzymes.
(Z)-endoxifen is a proprietary, novel Selective Estrogen Receptor Modulator (SERM), which is a class of drug that blocks estrogen from connecting with breast cancer cells, with the intent of keeping the cells from multiplying. The company is developing oral (Z)-endoxifen for the potential prevention and treatment of breast cancer. It has completed four Phase 1 clinical studies (including a study in men) and two Phase 2 clinical studies with its proprietary (Z)-endoxifen (including oral and topical formulations). The company has also developed clinical manufacturing capabilities through qualified third parties.
(Z)-endoxifen is currently being investigated in four Phase 2 trials:
EVANGELINE: EVANGELINE is a Phase 2 randomized study evaluating (Z)-endoxifen as neoadjuvant therapy for premenopausal women with primary ER+, HER2– breast cancer. The trial will enroll approximately 190 patients across up to 25 U.S. sites and is divided into two parts:
Part 1: Pharmacokinetic (PK) Run-In Cohort: A 40 mg/day cohort was opened in February 2023 to assess if plasma steady state concentrations (Css) of 500 to 1000 ng/mL, which is required for optimal PKC-ß inhibition, could be achieved. Subsequently, an 80 mg/day PK cohort was initiated and fully enrolled in July 2024.
Data from both the 40 mg and 80 mg cohorts, which included 12-week and 24-week Magnetic Resonance Imaging (MRI) and safety assessments, showed that no patients in the 40 mg cohort achieved the target plasma Css. In the 80 mg cohort, approximately 50% of patients receiving (Z)-endoxifen with Ovarian Function Suppression (OFS or goserelin), and 38% of patients receiving (Z)-endoxifen alone reached the target plasma Css, with an average plasma Css of 484 ng/mL.
(Z)-endoxifen was well tolerated overall. No significant Grade 3 or 4 toxicities were observed, although four gynecologic events were reported in the 80 mg group, including one Grade 3 hemorrhagic ovarian cyst.
In January 2025, based on an analysis of Part 1 of the study, which included the PK, efficacy, and safety data, the company further revised the study protocol to focus on the 40 mg per day dose, a dose to be sufficient to achieve tumor Css levels >500 ng/g for effective PKC-ß1 targeting.
Part 2: The Treatment Cohort: This cohort is expected to be initiated in the first half of 2025 and compares two treatment arms: Part 2a, which assesses (Z)-endoxifen plus goserelin for patients with baseline Ki-67 >10%, and Part 2b, which assesses (Z)-endoxifen on its own for patients with baseline Ki-67 =10%.
The primary objective of Part 2a is to determine if the endocrine sensitive disease rate (ESDR), which is defined as the percentage of patients with Ki-67 =10% after 4 weeks of treatment in patients given (Z)-endoxifen plus goserelin is non-inferior to the ESDR in patients given exemestane plus goserelin, in patients with baseline Ki-67 =10%.
Karisma-(Z)-endoxifen: Karisma-(Z)-endoxifen is a Phase 2 study of the company’s proprietary oral (Z)-endoxifen in healthy premenopausal women with measurable mammographic breast density (MBD). In November 2024, the Karisma-(Z)-Endoxifen study reported data that showed the potential of low-dose (Z)-endoxifen to significantly reduce MBD, a key risk factor for breast cancer, while showing a favorable safety profile. The randomized, double-blind, placebo-controlled study enrolled 240 premenopausal women aged 40-55, randomized to one of three arms: placebo, 1 mg, or 2 mg of daily oral (Z)-endoxifen for six months.
Based on input received in March 2020 from the FDA and Swedish Medical Products Agency, reduction in MBD may not be an approvable indication unless the company can demonstrate that (Z)-endoxifen also reduces the incidence of breast cancer. The company may therefore conduct additional studies of (Z)-endoxifen to assess its correlation with the risk of breast cancer and/or reduction in the incidence of new breast cancers.
I-SPY 2 Endocrine Optimization Pilot (EOP): I-SPY 2 EOP is a Phase 2 trial investigating (Z)-endoxifen in the neoadjuvant treatment setting, which is the window of time between a diagnosis and the primary treatment. The intent of neoadjuvant therapy is to slow the growth of the cancer or even shrink the cancer prior to surgery.
The I-SPY 2 trial is being conducted through a partnership with Quantum Leap Healthcare Collaborative (QLHC), which was established in 2005 by medical researchers at the University of California, San Francisco, and Silicon Valley entrepreneurs to encourage the development of innovative breast cancer therapies like (Z)-endoxifen. The platform trial enrolled patients with newly diagnosed ER+ invasive breast cancer. Participants in the study were treated with 10 mg of (Z)-endoxifen daily for up to 24 weeks prior to surgery. Efficacy measures include reduction in Ki-67, a marker for tumor cell proliferation, and the objective response rate as measured by MRI. The (Z)-endoxifen treatment cohort of 20 participants completed full enrollment in the first quarter of 2024.
On October 31, 2024, a preliminary data analysis was released, which showed that (Z)-endoxifen met the primary endpoint with 95% (19/20 patients) receiving >75% of the planned treatment. The data also showed (Z)-endoxifen activity in rapidly reducing key biomarkers, such as Ki-67, by 69% from baseline and a 30.4% reduction in functional tumor volume (FTV) from baseline after three weeks of treatment.
(Z)-endoxifen was well tolerated in this study, with the most common side effects being mild, including hot flashes, insomnia, and fatigue.
On April 15, 2024, the company announced its participation in a new study arm of I-SPY 2 EOP, which was initiated to evaluate its proprietary (Z)-endoxifen in combination with abemaciclib (VERZENIO), a cyclin-dependent kinase (CDK) 4/6 inhibitor marketed by Eli Lilly and Company, in women with ER+/HER2- breast cancer.
Participants in this trial were initially intended to receive 80 mg of (Z)-endoxifen once daily alongside 150 mg of abemaciclib twice daily for 24 weeks prior to surgery.
RECAST DCIS: RECAST DCIS is a Phase 2 platform study investigating (Z)-endoxifen in women diagnosed with Ductal Carcinoma In Situ (DCIS). The goal of the study, which was initiated in October 2023, is to prevent the progression of DCIS to breast cancer. Participants receive six months of treatment with a 10 mg oral dose of (Z)-endoxifen daily, with the intent of determining their suitability for long-term active surveillance without surgery. On February 22, 2024, the first patient was dosed with the company’s proprietary SERM (Z)-endoxifen.
Other Programs
Forthcoming Programs: On March 11, 2025, the company announced its strategic decision to pursue a metastatic breast cancer indication for (Z)-endoxifen.
Pre-Clinical Program: The company sponsors strategic research, and has agreements with Weill Cornell Medicine, with the goal of making TNBC more treatable.
Investment in CAR-T Company: During the fourth quarter of 2024, Dynamic Cell Therapies, Inc. (DCT), a U.S. private company previously focused on Chimeric Antigen Receptor (CAR) T-cell therapies, laid off all employees and ceased operations. The company has recorded impairment charges related to its investment in DCT.
Research and Development Phase
The company’s research and development expenses for the year ended December 31, 2024, were approximately $14.1 million.
Intellectual Property
As of February 3, 2025, based on a review of the company’s patent portfolio, it owns and maintains 13 issued patents (five U.S. patents and eight international patents), and is pursuing 119 pending patent applications (28 U.S. patent applications, and 91 international patent applications, including two allowed U.S. applications and three allowed international applications) directed to the company’s (Z)-endoxifen therapies, immunotherapies, such as CAR-T therapies, and other therapies. The company continues to evaluate its patent portfolio on a regular basis and is no longer pursuing or maintaining patents, patent applications, or technologies that it has determined are no longer core to its business as a result of evolving business goals.
Government Regulation
The company is subject to extensive regulation by the FDA and other federal, state, and local regulatory agencies. The Federal Food, Drug, and Cosmetic Act, or the FDCA, and its implementing regulations set forth, among other things, regulations for the execution of clinical studies, and the requirements for the testing, development, manufacture, quality control, safety, effectiveness, approval, labeling, storage, record keeping, reporting, distribution, import, export, advertising, and promotion of its products.
After receiving approval in the U.S., the company must comply with the FDA’s regulation of drug promotion and advertising, including requirements that communications be consistent with the FDA-approved labeling, truthful and non-misleading, and present a fair balance of risk and benefit information, and compliance with federal anti-kickback statutes, limitations on gifts and payments to physicians, and reporting of payments to certain third parties, among other requirements.
The company needs to submit an updated RMP, at the request of EMA or a national competent authority, or whenever the risk-management system is modified, especially as the result of new information being received that may lead to a significant change to the benefit-risk profile or as a result of an important pharmacovigilance or risk-minimization milestone being reached.
The company’s business activities outside of the U.S. are subject to anti-bribery or anti-corruption laws, regulations, industry self-regulation codes of conduct, and physicians’ codes of professional conduct or rules of other countries in which it operates, including the U.K. Bribery Act of 2010.
Numerous other comprehensive privacy laws have passed or are being considered in other states, as well as at the federal and local levels, which also exempt some data processed in the context of clinical trials; but others exempt covered entities and business associates subject to HIPAA altogether, further complicating compliance efforts, and increasing legal risk and compliance costs for the company and the third parties upon which it relies.
Specific health-care laws and regulations that the company is subject to include: the federal Anti-Kickback Statute; the federal Physician Self-Referral Law; the False Claims Act (FCA); the federal Civil Monetary Penalties Law; and the federal Physician Payments Sunshine Act.
History
The company was founded in 2008. The company was incorporated in the State of Delaware in 2009. The company was formerly known as Atossa Genetics Inc. and changed its name to Atossa Therapeutics, Inc. in January 2020.
The Analyst Price Target shows the analysts’ low, high, and average target at a glance.
