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Last update 26 Sep 2026

Tamoxifen Citrate

Last update 26 Sep 2026

Overview

R&D Status

Clinical Result

Translational Medicine

Overview

Basic Info

Drug Type

Small molecule drug

Synonyms

(Z)-2-(4-(1,2-Diphenyl-1-butenyl)phenoxy)-N,N-dimethylethanamine, (Z)-2-(para-(1,2-Diphenyl-1-butenyl)phenoxy)-N,N-dimethylamine, 1-p-beta-Dimethylaminoethoxyphenyl-trans-1,2-diphenylbut-1-ene

+ [20]

Target

Action

antagonists

Mechanism

ERs antagonists(Estrogen receptors antagonists)

Therapeutic Areas

NeoplasmsSkin and Musculoskeletal Diseases

Active Indication

Estrogen receptor positive breast cancerNoninfiltrating Intraductal CarcinomaBreast Cancer

Inactive Indication

Advanced Malignant Solid NeoplasmBreast Cancer, FamilialDementia+ [10]

Originator Organization

AstraZeneca PLC

Active Organization

Mayne Pharma Commercial LLC

Suzhou First Pharmaceutical Co., Ltd.AstraZeneca KK

Inactive Organization

AstraZeneca PLCAstraZeneca Pharmaceuticals LP

Daré Bioscience, Inc.

License Organization

Midatech Pharma US, Inc.

DARA BioSciences, Inc.

Drug Highest PhaseApproved

First Approval Date

United States (30 Dec 1977),

Breast Cancer

RegulationOrphan Drug (European Union)

Structure/Sequence

Molecular FormulaC32H37NO8

InChIKeyFQZYTYWMLGAPFJ-OQKDUQJOSA-N

CAS Registry54965-24-1

442

Clinical Trials associated with Tamoxifen Citrate

NCT07729046

/ Not yet recruitingPhase 2IIT

Neu Direction: A Single Center Phase II Randomized Clinical Trial to Assess the Efficacy of Adding HER Inhibition to Standard of Care in Patients With Metastatic MLH1-low Endocrine-resistant ER+/HER2- Breast Cancer

The goal of this clinical trial is to learn if neratinib, an FDA-approved oral pan-HER2/3/4 inhibitor, improves disease control for participants with metastatic endocrine-resistant ER+/HER2-negative breast cancer. Neratinib is already approved for the treatment of HER2-postive breast cancers. The study will also learn about the safety of adding this drug to standard of care treatments. The main questions it aims to answer are:
1. Does adding neratinib to standard of care systemic therapy improve disease control for patients with metastatic hormone-driven breast cancer that is resistant to endocrine therapy?
2. What side effects do participants have when adding neratinib to standard of care therapy? Researchers will compare standard of care endocrine therapy regimens with and without neratinib to see if neratinib improves control of treatment-resistant metastatic breast cancer that has continued to progress while eon first line endocrine therapy.
Participants will:
1. Take standard of care endocrine therapy for metastatic endocrine-resistant breast cancer as determined by their medical oncologist or standard of care therapy with neratinib daily
2. Visit the clinic every 3 months for checkups, tests and imaging studies

Start Date01 Jul 2027

Sponsor / Collaborator

University of California San Diego

NCT07806630

/ Active, not recruitingPhase 2IIT

SHORTened Duration of TAMoxifen for Risk Reduction in Breast Intraepithelial Neoplasms in Post-menopausal Women

The purpose of this study is to learn whether a shorter-duration, low-dose tamoxifen regimen can reduce the risk of developing breast cancer or breast cancer recurrence in post-menopausal women who are at increased risk for breast cancer.

Start Date01 Sep 2026

Sponsor / Collaborator

Rutgers State University of New Jersey

PACTR202607871406155

/ SuspendedNot ApplicableIIT

Circadian Optimisation of Tamoxifen Administration Improves Disease-Free and Overall Survival in High-Risk ER-Positive/HER2-Negative Early Breast Cancer: A Multi-Centre Retrospective Cohort Study

Start Date01 Aug 2026

Sponsor / Collaborator-

100 Clinical Results associated with Tamoxifen Citrate

100 Translational Medicine associated with Tamoxifen Citrate

100 Patents (Medical) associated with Tamoxifen Citrate

11,640

Literatures (Medical) associated with Tamoxifen Citrate

01 Aug 2026·JOURNAL OF CLINICAL ONCOLOGY

Low-Dose Tamoxifen in Noninvasive Breast Neoplasia: Long-Term Results From an Individual-Participant Data Pooled Analysis

Article

Author: Cortesi, Laura ; Serra, Patrizia ; Digennaro, Maria ; Debiasi, Marcio ; Rizzo, Roberta ; Buttiron Webber, Tania ; Bonanni, Bernardo ; Johansson, Harriet ; Giordano, Livia ; Sousa, Berta ; DeCensi, Andrea ; Gandini, Sara ; Carbone, Alessio ; Serrano, Davide ; Aprile, Giuseppe ; Aurilio, Gaetano ; Gallerani, Elisa ; Lazzeroni, Matteo ; Cagossi, Katia ; Guerrieri-Gonzaga, Aliana ; Millo, Francesco ; Gouveia, Pedro ; Puntoni, Matteo

PURPOSE:

Tamoxifen 20 mg once-daily reduces the risk of breast cancer recurrence after ductal carcinoma in situ (DCIS), but its use is limited by adverse effects. Lower doses may be effective, but benefit durability and differences according to menopausal status and site of recurrence remain uncertain.

METHODS:

We conducted an individual-participant pooled analysis of three clinical studies involving women with estrogen receptor–positive or unknown DCIS, microinvasive carcinoma, or high-risk breast lesions. Participants received low-dose tamoxifen (5 mg once daily or 10 mg once-every other day for 2-5 years) or a control intervention. The primary end point was breast cancer–free interval, defined as the first occurrence of any ipsilateral or contralateral invasive breast cancer, DCIS, regional recurrence, or distant recurrence. Hazard ratios (HRs) were estimated with mixed-effects Cox models accounting for between-study variability.

RESULTS:

Among 1,545 women included with a median follow-up of 9.4 years, low-dose tamoxifen reduced breast cancer events overall, with evidence of treatment heterogeneity according to menopausal status ( P = .01). In postmenopausal women, breast cancer events occurred in 40 of 335 receiving low-dose tamoxifen versus 93 of 401 controls (HR, 0.51 [95% CI, 0.35 to 0.73]), with a 10-year absolute reduction of 11.2%. Among premenopausal women, no significant reduction was observed (HR, 0.90 [95% CI, 0.70 to 1.17]), although contralateral breast cancer was reduced (HR, 0.45 [95% CI, 0.26 to 0.76]). Serious adverse events were infrequent and similar between groups.

CONCLUSION:

Low-dose tamoxifen was associated with a sustained reduction in breast cancer events, with differences by menopausal status and site of event. These findings support endocrine dose de-escalation to improve the benefit-risk profile of preventive therapy in DCIS and high-risk lesions.

01 Apr 2026·NEUROMUSCULAR DISORDERS

Safety and Efficacy of Tamoxifen in Patients with Duchenne muscular dystrophy: open Label Extension of TAMDMD Trial

Article

Author: Spinty, Stefan ; Zwingli, Gaëtan ; Lawrence, Fiona ; Lopez Lobato, Mercedes ; Houwen-van Opstal, Saskia ; Schara-Schmidt, Ulrike ; Laugel, Vincent ; Amthor, Helge ; Nascimento Osorio, Andrés ; Schaedelin, Sabine ; Rubino-Nacht, Daniela ; Hafner, Patricia ; Deconinck, Nicolas ; Fischer, Dirk ; Horrocks, Iain ; Putananickal, Niveditha ; von Moers, Arpad ; Childs, Anne-Marie ; Henzi, Bettina C ; Dorchies, Olivier M ; Nagy, Sara ; Schmidt, Simone

Safety and efficacy of tamoxifen in boys with Duchenne muscular dystrophy was assessed in the double-blind, randomised, placebo-controlled, multicenter phase 3 trial (TAMDMD), which was followed by an 48 weeks open label extension study. The aim of the open label extension study was to investigate if earlier initiation of tamoxifen could reduce the progression of the disease compared to delayed initiation of tamoxifen. Of the initial TAMDMD trial participants, 66 patients were enrolled in the open label extension (OLE). The objective was to investigate the efficacy of prolonged treatment with tamoxifen 20 mg daily, adjunct to corticosteroids, in individuals with DMD over 48 weeks. We aimed to analyse the sustained effect and the timing effect of tamoxifen in patients with DMD on the basis of a set of motor function tests. The sustained effect corresponds to the treatment effect seen in the tamoxifen treatment arm of the RCT phase of the trial being sustained after all patients got the treatment in the OLE phase. The timing effect addresses if patients with earlier tamoxifen initiation show more favourable disease trajectory than patients with delayed tamoxifen initiation. This study was registered with ClinicalTrials.gov (NCT03354039). Between May 28th 2019 and July 28th 2021, 66 patients in 10 study centres in seven European countries could be enrolled into the OLE phase. Of those, 32 had previously been treated with tamoxifen and 34 had been assigned to placebo. The efficacy outcome defined as the change in the motor function did not differ significantly between the early tamoxifen treatment group and the delayed tamoxifen treatment group. There was neither a sustained nor a timing effect of tamoxifen. Overall tamoxifen was well tolerated. No deaths or life-threatening serious adverse events occurred. The OLE phase of the TAMDMD trial showed that treatment with tamoxifen continued to be well tolerated overall; however, there was neither a sustained nor a timing effect of tamoxifen treatment in patients with DMD. We cannot provide statistical nor clinical evidence that prolonged treatment with tamoxifen is effective in delaying disease progression in DMD when used as an adjunct to corticosteroids.

24 Mar 2026·JOURNAL OF BIOMOLECULAR STRUCTURE & DYNAMICS

Deciphering the in silico molecular mechanism of coumestrol activity for uterine fibroids remedy: a promising estrogenic target drug candidate

Article

Author: Chtita, Samir ; Munir, Aqsa ; Olowosoke, Christopher Busayo ; Ojo, Oluwafemi Adeleke ; Khedraoui, Meriem ; Sofela, Salimat Opeyemi ; Ibisanmi, Tope Abraham ; Taiwo, Odunayo ; Eze, Chioma Joy ; Osuagwu, Olachi Lilian ; Babatope, Valerie Onyia

Uterine fibroids (UF) are reproductive conditions that occur as tumours in the womb. It is a gynecological outgrowth of diverse sizes often allied with infertility risks that might require surgery to reduce the complication in the worst-case scenario in women. Recent studies have uncovered that estrogen can induce and facilitate other target pathways' action on target cells for UF's pathogenesis, among the targets probed for pharmaceutical intervention. This study screens the interaction effects of 32 phytochemicals from indigenous and adopted potent Chinese plants and herbs; Chamomile, Pomegranate, Red clover, Cinnamomum, and Date palm, against estrogen receptor alpha (ESRα) to serve for anti-UF drug candidates using in silico tools through the molecular mechanisms. The interaction identifies coumestrol as the best-docked candidate (-9.6 kcal/mol) with a correlation to the binding free energy (-30.487 kcal/mol) as compared to the standard drug tamoxifen (-9.3 kcal/mol; -46.928 kcal/mol). The downstream post-docking evaluation reveals coumestrol to have excellent pharmacokinetics, drug-likeness, leadlikeness (no violation), less toxic (LD50; 2991 mg/kg), and highly interactive with ESRα. Coumestrol was top-ranked for ESRα (1QKU) target by PharmMapper among 300 human protein targets, with a z-score of 1.19368. The density functional theory (DFT) and dynamic simulation of 200 ns reveal regions of coumestrol structure and its complex that contribute to the chemical reactivity, stability, flexibility, and compactness of druggability. Ultimately, coumestrol emerged as a potential candidate suitable for anti-UF management, therefore future direction for its application should be on the design and synthesis of new structural derivatives for further in silico, in vitro, and in vivo studies.

139

News (Medical) associated with Tamoxifen Citrate

24 Sep 2026

·www.businesswire.com

New Data Shows Physicians Changed Extended Endocrine Therapy Recommendations for Over 40% of Patients Following Breast Cancer Index Testing

MARLBOROUGH, Mass.--(BUSINESS WIRE)--Hologic, Inc. and its subsidiary, Biotheranostics, Inc., today announced newly published data in JAMA Network Open showing that Breast Cancer Index® (BCI®) test results led physicians to change their extended endocrine therapy recommendations for 42% of patients. In two-thirds of those cases, physicians changed their recommendation against extending treatment.1 "[This study] reinforces the clinical utility of the Breast Cancer Index test to provide individualized insight into tumor biology that can meaningfully change how physicians and patients approach these decisions.” - Tara B. Sanft, M.D. The findings come from a large-scale BCI Registry Study conducted across multiple institutions at the Sarah Cannon Research Institute, involving nearly 3,000 patients with early-stage, hormone receptor-positive (HR+) breast cancer who received the BCI test. 1 Endocrine therapy is the standard of care for breast cancer survivors to help limit the effects of hormones that can fuel cancer growth — but it is also often the longest phase of a breast cancer patient’s treatment and can cause adverse health outcomes that impact quality of life.2-8 In this analysis, 83% of patients reported side effects ranging from muscle and joint pain to vaginal, sexual and psychological complaints.1 “Decisions about extended endocrine therapy can be challenging, and assumptions based on standard information, such as nodal involvement and tumor size and grade, may be misleading,” said Tara B. Sanft, M.D., of Hartford Healthcare and lead author of the study. “This final analysis of the BCI Registry Study reinforces the clinical utility of the Breast Cancer Index test to provide individualized insight into tumor biology that can meaningfully change how physicians and patients approach these decisions.” Approximately half of recurrences in HR+ breast cancer occur beyond five years post-diagnosis.9 Yet studies suggest that roughly 30–50% of women discontinue endocrine therapy before reaching the five-year mark, often due to side effects or uncertainty about whether continued treatment is necessary.10-13 Multiple trials have demonstrated that while extended endocrine therapy may be beneficial for some women in reducing their risk of late recurrence, not all benefit.14-17 As of July 2026, physicians can now access an updated report option from the same BCI test, providing additional clinical insights earlier — at the time of diagnosis — to support greater clarity as patients plan for treatment.18-20 The updated report offers additional context on 10-year recurrence risk, which can either reinforce the case for medication adherence or help identify whether a patient’s risk may be low enough to consider a less intensive approach to endocrine therapy. “The Breast Cancer Index test’s updated report supports a more informed plan for the years ahead, allowing physicians to further personalize patient care and provide them with a clear roadmap from the time of diagnosis,” said Lloyd Sanders, Vice President and General Manager, Oncology Services at Hologic. “That clarity can make a real difference as patients plan for treatment and life as a cancer survivor.” The BCI test is the only genomic assay recognized by both the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) and the ASCO® Clinical Practice Guideline to predict which patients with early-stage, HR+, HER2- breast cancer are likely to benefit from extended endocrine therapy.2-3 The test has been used by more than 10,000 healthcare providers and evaluated across multiple clinical studies involving more than 15,000 patients.14-27 The recently published results from the BCI Registry Study solidify the clinical impact and value of the Breast Cancer Index test beyond its extensive validation and exclusive guideline recognition. Additional clinical insights from the same established test now enable earlier treatment planning and greater Clarity from the Start™.18-20 About the Breast Cancer Index Test The Breast Cancer Index test is a molecular, gene expression-based test uniquely positioned to provide information to help physicians individualize treatment decisions for patients with early-stage, HR+ breast cancer. This breakthrough test helps oncology care teams and patients navigate the difficult trade-offs between taking steps to prevent recurrence of their disease and facing significant side effects and safety challenges related to unnecessary treatment. The Breast Cancer Index test has guideline designation from the American Joint Committee on Cancer for cancer staging based on molecular profile. The ASCO® Clinical Practice Guideline and the NCCN Guidelines® acknowledge the Breast Cancer Index test as a biomarker to help inform extended endocrine treatment decisions.2-3 The Breast Cancer Index test is intended for routine clinical use, and physician treatment decisions based on results are the responsibility of the physician. It is a sole-source laboratory-developed test (LDT) performed by Biotheranostics, Inc., a CLIA-certified and CAP-accredited diagnostic laboratory. For more information and the full intended use and limitations, visit www.breastcancerindex.com. About Hologic, Inc. Hologic, Inc. is a global leader in women’s health dedicated to developing innovative medical technologies that effectively detect, diagnose and treat health conditions and raise the standard of care around the world. To learn more, visit www.hologic.com and connect with us on LinkedIn, Facebook, X, Instagram and YouTube. Forward-Looking Statements This news release may contain forward-looking information that involves risks and uncertainties, including statements about the use of Hologic products. There can be no assurance these products will achieve the benefits described herein or that such benefits will be replicated in any particular manner with respect to an individual patient, as the actual effect of the use of the products can only be determined on a case-by-case basis. In addition, there can be no assurance that these products will be commercially successful or achieve any expected level of sales. Hologic expressly disclaims any obligation or undertaking to release publicly any updates or revisions to any such statements presented herein to reflect any change in expectations or any change in events, conditions or circumstances on which any such data or statements are based. Hologic, Biotheranostics, Breast Cancer Index, BCI and Clarity from the Start are trademarks and/or registered trademarks of Hologic, Inc. and/or its subsidiaries in the United States and/or other countries. All other trademarks are the property of their respective owners. References Sanft T, et al. JAMA Netw Open. 2026;9(9):e2634974. Referenced with permission from the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) for Breast Cancer V.6.2026. © National Comprehensive Cancer Network, Inc. 2026. All rights reserved. Accessed September 8, 2026. To view the most recent and complete version of the guideline, go online to NCCN.org. NCCN makes no warranties of any kind whatsoever regarding their content, use or application and disclaims any responsibility for their application or use in any way. Andre F, et al. J Clin Oncol. 2022;40(16):1816-1837. Referenced with permission from the American Society of Clinical Oncology (ASCO® Clinical Practice Guideline) Clinical Practice Guideline Biomarkers for Adjuvant Endocrine and Chemotherapy in Early-Stage Breast Cancer. © American Society of Clinical Oncology. 2026. All rights reserved. To view the most recent and complete version of the guideline, go online to https://ascopubs.org/jco/special/guidelines . ASCO makes no warranties of any kind whatsoever regarding their content, use of application and disclaims any responsibility for their application or use in any way. Breastcancer.org. Side Effects of Hormonal Therapy for Breast Cancer. Breastcancer.org. Last updated June 11, 2026. Accessed on September 8, 2026. https://www.breastcancer.org/treatment/hormonal-therapy/side-effects U.S. Food & Drug Administration. Armidex Full Prescribing Information. Last updated December 16, 2024. Accessed June 16, 2026. https://www.accessdata.fda.gov/drugsatfda_docs/label/2024/020541s036lbl.pdf U.S. Food & Drug Administration. Aromasin Full Prescribing Information. Last updated December 16, 2024. Accessed September 8, 2026. https://www.accessdata.fda.gov/drugsatfda_docs/label/2024/020753s025lbl.pdf U.S. Food & Drug Administration. Femara Full Prescribing Information. Last updated September 16, 2025. Accessed September 8, 2026. https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/209092Orig1s025,209935Orig1s031lbl.pdf U.S. Food & Drug Administration. Soltamox Full Prescribing Information. Last updated April 8, 2019. Accessed June 16, 2026. https://www.accessdata.fda.gov/drugsatfda_docs/label/2019/021807s006lbl.pdf Pan H, et al. N Engl J Med. 2017;377:1836-1846. Hershman DL, et al. J Clin Oncol. 2010;20;28(27):4120-4128. Friese CR, et al. Breast Can Res Treat. 2013;138(3):931-39. Saha P, et al. J Clin Oncol. 2017;(35):3113-3122. Wei J, et al. Breast Cancer Res Treat. 2025;214(2):239-246. Sgroi DC, et al. J Natl Cancer Inst. 2013;105(14):1036-1042. Bartlett JMS, et al. Clin Cancer Res. 2022;28(9):1871-1880. Noordhoek I, et al. Clin Cancer Res. 2021;27(1):311-319. Mamounas EP, et al. Clin Cancer Res. 2024;30(9):1984-1991. Jilderda MF, et al. Clin Cancer Res. 2025;3;31(11):2222-2229. Jilderda MF, et al. npj Breast Cancer. 2026;12;21. O’Regan RM, et al. Breast. 2026;86:104714. Data on file. Zhang Y, et al. Clin Cancer Res. 2013;19(15):4196-4205. Sgroi DC, et al. Lancet Oncol. 2013;14(11):1067-1076. Zhang Y, et al. Clin Cancer Res. 2017;23(23):7217-7224. Bartlett JMS, et al. Clin Cancer Res. 2024;30(8):1509-1517. O’Regan RM, et al. JAMA Oncol. 2024;10;(10):1379-1389. O’Regan RM, et al. JAMA Netw Open. 2025;8(11):e2540931.

ASCOClinical Result

24 Sep 2026

·www.prnewswire.com

Atossa Therapeutics CEO Dr. Steven Quay to Participate in ARDD 2026 Panel on Clinical Trials and Regulatory Pathways for Diseases of Aging

Panel at Harvard University will explore translating evidence in diseases of aging into new therapeutics and regulatory pathways SEATTLE, Sept. 24, 2026 /PRNewswire/ -- Atossa Therapeutics, Inc. (Nasdaq: ATOS) ("Atossa" or the "Company"), a clinical-stage biopharmaceutical company, today announced that Steven Quay, M.D., Ph.D., Atossa's President and Chief Executive Officer, will participate as a panelist at the 13th Aging Research and Drug Discovery Meeting (ARDD 2026), being held October 1–3, 2026, at the David Rubenstein Treehouse at Harvard University in Boston, MA. The discussion will explore the translation of scientific evidence in aging and age-related diseases into clinical development programs, including the design of clinical trials, development of new therapeutics and regulatory considerations for advancing potential treatments to patients. "Advances in our understanding of the biology underlying aging and progressive disease are creating opportunities to approach drug development in new ways," said Dr. Quay. "Turning promising science into meaningful therapies requires clinical trials that are grounded in strong biological evidence, use appropriate and measurable endpoints, and are designed with a clear understanding of the regulatory pathway. These considerations are particularly relevant as Atossa expands its development efforts in rare diseases, and I look forward to exchanging perspectives with this distinguished group of leaders." ARDD brings together leaders from the pharmaceutical and biotechnology industries, academia, clinical medicine and other disciplines to discuss advances in aging research and the translation of scientific discoveries into potential new medicines. The 2026 program includes discussions addressing clinical trials and regulatory pathways, drug discovery and development, emerging technologies and approaches to extending healthy longevity. Event Details Event: ARDD 2026 – Aging Research and Drug Discovery Meeting Panel: Clinical Trials in Diseases of Aging: From Evidence to New Therapeutics and Regulatory Pathways Date: Thursday, October 1, 2026 Time: 11:20 a.m. – 12:00 p.m. ET Location: David Rubenstein Treehouse at Harvard University, Boston, Massachusetts Moderator: Sebastien Thuault, Editor at Nature Medicine Other Panelists: Jill Lee, Director, Regulatory Policy & Intelligence at Novo Nordisk; Calum MacRae, Professor at Mass General Brigham; and Steve Horvath, Professor at UCLA Additional information about ARDD 2026 and the full program is available at agingpharma.org. About Atossa Therapeutics Atossa Therapeutics, Inc. (Nasdaq: ATOS) is a clinical-stage biopharmaceutical company developing innovative medicines in oncology and other areas of significant unmet need. The Company's lead product candidate, (Z)-endoxifen, is currently in development across several clinical settings. (Z)-Endoxifen is a potent Selective Estrogen Receptor Modulator/Degrader (SERM/D) with demonstrated activity across multiple mechanisms of interest. Atossa is evaluating its potential applications in oncology and rare diseases. The Company's proprietary oral formulation has shown a favorable safety profile and pharmacology distinct from tamoxifen, including ER-targeted effects and PKC inhibition. Atossa's (Z)-endoxifen is not approved for any indication. Atossa's (Z)-endoxifen program is supported by a growing global intellectual property portfolio, including multiple recently issued U.S. patents and numerous pending applications worldwide. More information is available at . Forward-Looking Statements This press release contains certain "forward-looking statements" within the meaning of applicable securities laws, including, but not limited to, our expectations regarding the Company's development and regulatory strategy and related milestones, including the potential indications that the Company may pursue for (Z)-endoxifen, the potential role of (Z)-endoxifen in endocrine therapies, the potential for (Z)-endoxifen to receive regulatory approval and the timing thereof, and the potential market and growth opportunities for the Company. Words such as "expect," "potential," "continue," "may," "will," "should," "could," "would," "seek," "intend," "plan," "estimate," "anticipate," "believe," "design," "predict," "future," or other similar expressions or statements regarding intent, belief or current expectations, are forward-looking statements. Forward-looking statements in this press release are subject to risks and uncertainties that may cause actual results, outcomes, or the timing of actual results or outcomes to differ materially from those projected or anticipated, including, without limitation, risks and uncertainties associated with: our ability to successfully execute our strategy to shorten our clinical development timelines and pursue a MAS indication or other indications for our lead program, (Z)-endoxifen; expected timing, completion and results of our preclinical studies, clinical trials and research and development programs; the unpredictable relationship between preclinical study results and clinical study results; the timing or likelihood of regulatory filings and approvals; the outcome or timing of necessary regulatory approvals; our ability to maintain compliance with Nasdaq listing requirements; our ability to establish and maintain intellectual property rights covering our products; the impact of general macroeconomic conditions on our business; our ability to raise capital; and other risks and uncertainties detailed from time to time in Atossa's filings with the SEC, including, without limitation, its Annual Reports on Form 10-K and Quarterly Reports on Form 10-Q. Forward-looking statements are presented as of the date of this press release. Except as required by law, we do not intend to update any forward-looking statements. SOURCE Atossa Therapeutics Inc 21% more press release views with Request a Demo

11 Sep 2026

·www.astrazeneca.com

Update on SERENA-4 Phase III trial of Etcamah in combination with palbociclib in upfront 1st-line advanced ER-positive breast cancer

This announcement contains inside information SERENA-4 trial did not meet primary objective of statistically significant improvement in progression-free survival, however a numerical improvement was observed Etcamah is the only oral SERD to demonstrate benefit in 1st-line setting and is approved for patients with an emergent ESR1 tumour mutation based on SERENA-6 The SERENA-4 Phase III trial of AstraZeneca’s Etcamah (camizestrant) in combination with palbociclib, a cyclin-dependent kinase (CDK) 4/6 inhibitor, did not meet the primary endpoint of progression-free survival (PFS), however a numerical improvement was observed in the upfront 1st-line treatment of patients with estrogen receptor (ER)-positive, HER2-negative advanced breast cancer who have not received any systemic treatment for advanced disease. The trial evaluated the Etcamah combination versus treatment with an aromatase inhibitor (anastrozole) in combination with palbociclib. Susan Galbraith, Executive Vice President, Oncology Haematology R&D, AstraZeneca, said: “Whilst we are disappointed by the SERENA-4 outcome, it sharpens our focus on maximising the number of patients who can benefit from Etcamah today based on SERENA-6 and reinforces the importance of ESR1 testing for patients on first-line therapy. Early breast cancer represents an important opportunity, and we remain confident in the long-term potential of Etcamah in the early setting as we advance our broader programme.” The safety profile of Etcamah in combination with palbociclib in SERENA-4 was consistent with the known safety profile of each medicine, with no new safety concerns identified. Data will be shared in due course. Etcamah in combination with a CDK4/6 inhibitor (palbociclib, ribociclib or abemaciclib) is approved in the US, EU, Japan and several other countries for the treatment of adult patients with hormone receptor (HR)-positive (or ER-positive), HER2-negative locally advanced or metastatic breast cancer upon detection or emergence of ESR1 mutation during 1st-line endocrine-based therapy, based on the results from the SERENA-6 Phase III trial. Etcamah is currently being evaluated in the most comprehensive oral SERD development programme in early breast cancer. Encompassing approximately 10,000 patients, the CAMBRIA-1 and CAMBRIA-2 Phase III trials are designed for patients at both intermediate and high risk of recurrence in the adjuvant setting, evaluating Etcamah as a monotherapy, in combination with CDK4/6 inhibitors and following CDK4/6 inhibitor treatment to address areas of unmet need in HR-positive, HER2-negative breast cancer. Notes ER-positive breast cancer Breast cancer is the second most common cancer and one of the leading causes of cancer-related deaths worldwide.1 More than two million patients were diagnosed with breast cancer in 2024, with more than 690,000 deaths globally.1 While survival rates are high for those diagnosed with early breast cancer, only about 30% of patients diagnosed with or who progress to metastatic disease are expected to live five years following diagnosis.2 HR-positive breast cancer, characterised by the expression of estrogen or progesterone receptors, or both, is the most common subtype of breast cancer with 70% of tumours considered HR-positive and HER2-negative.2 ERs often drive the growth of HR-positive breast cancer cells.3 More than 97% of HR-positive breast cancer tumours are ER-positive.4,5 SERENA-4 SERENA-4 is a Phase III, double-blind, randomised trial evaluating the efficacy and safety of camizestrant in combination with palbociclib, a CDK4/6 inhibitor, versus treatment with an aromatase inhibitor (AI) (anastrozole) in combination with palbociclib in patients with ER-positive, HER2-negative advanced breast cancer (patients with either locally advanced disease, or metastatic disease). The global trial enrolled 1,371 adult patients, newly diagnosed with Stage IV de novo or recurrent disease who had not received any systemic treatment for metastatic disease. Patients with recurrence from early-stage disease had received at least 24 months of standard adjuvant endocrine therapy (AI or tamoxifen), and at least 12 months had elapsed since the last dose of adjuvant AI therapy without disease progression on treatment. The primary endpoint of the SERENA-4 trial is PFS as assessed by investigator, with secondary endpoints including OS, PFS2, and health-related quality of life (HRQOL). Etcamah Etcamah is a potent, next-generation oral selective estrogen receptor degrader (SERD) and complete ER antagonist, administered orally, once daily. The recommended dose of Etcamah in combination with a CDK4/6 inhibitor is 75mg. Etcamah in combination with a CDK4/6 inhibitor (palbociclib, ribociclib or abemaciclib) is approved in the US, EU, Japan and several other countries for the treatment of adult patients with HR-positive (or ER-positive), HER2-negative locally advanced or metastatic breast cancer upon detection or emergence of ESR1 mutation during 1st-line endocrine-based therapy, based on the results from the SERENA-6 Phase III trial. The broad, robust and innovative Etcamah clinical development programme, including the CAMBRIA-1 and CAMBRIA-2 Phase III trials, is evaluating the safety and efficacy of Etcamah when used as a monotherapy or in combination with CDK4/6 inhibitors to address a number of areas of unmet need in HR-positive, HER2-negative breast cancer. AstraZeneca in breast cancer Driven by a growing understanding of breast cancer biology, AstraZeneca is challenging, and redefining, the current clinical paradigm for how breast cancer is classified and treated to deliver even more effective treatments to patients in need – with the bold ambition to one day eliminate breast cancer as a cause of death. AstraZeneca has a comprehensive portfolio of approved and promising compounds in development that leverage different mechanisms of action to address the biologically diverse breast cancer tumour environment. With Enhertu (trastuzumab deruxtecan), a HER2-directed antibody drug conjugate (ADC), AstraZeneca and Daiichi Sankyo are aiming to improve outcomes in previously treated HER2-positive, HER2-low and HER2-ultralow metastatic breast cancer and are exploring its potential in earlier lines of treatment and in new breast cancer settings. In HR-positive breast cancer, AstraZeneca continues to improve outcomes with foundational medicines Faslodex (fulvestrant) and Zoladex (goserelin) and aims to reshape the HR-positive space with first-in-class AKT inhibitor, Truqap (capivasertib), the TROP-2-directed ADC, Datroway (datopotamab deruxtecan) and next-generation oral SERD, Etcamah. PARP inhibitor Lynparza (olaparib) is a targeted treatment option that has been studied in early and metastatic breast cancer patients with an inherited BRCA mutation. AstraZeneca with MSD (Merck & Co., Inc. in the US and Canada) continue to research Lynparza in these settings. AstraZeneca is also exploring the potential of saruparib, a potent and selective inhibitor of PARP1, in combination with Etcamah or endocrine therapy in BRCA-mutated, HR-positive, HER2-negative advanced breast cancer. To bring much-needed treatment options to patients with triple-negative breast cancer, an aggressive form of breast cancer, AstraZeneca is collaborating with Daiichi Sankyo to evaluate the potential of Datroway alone and in combination with immunotherapy Imfinzi (durvalumab). AstraZeneca in oncology  AstraZeneca is leading a revolution in oncology with the ambition to provide cures for cancer in every form, following the science to understand cancer and all its complexities to discover, develop and deliver life-changing medicines to patients. The Company's focus is on some of the most challenging cancers. It is through persistent innovation that AstraZeneca has built one of the most diverse portfolios and pipelines in the industry, with the potential to catalyse changes in the practice of medicine and transform the patient experience.  AstraZeneca has the vision to redefine cancer care and, one day, eliminate cancer as a cause of death. AstraZeneca AstraZeneca (LSE/STO/NYSE: AZN) is a global, science-led biopharmaceutical company that focuses on the discovery, development, and commercialisation of prescription medicines in Oncology, Rare Disease, and BioPharmaceuticals, including Cardiovascular, Renal & Metabolism, and Respiratory & Immunology. Based in Cambridge, UK, AstraZeneca’s innovative medicines are sold in more than 125 countries and used by millions of patients worldwide. Please visit astrazeneca.com and follow the Company on Social Media @AstraZeneca. Contacts For details on how to contact the Investor Relations Team, please click here. For Media contacts, click here. References Matthew Bowden Company Secretary AstraZeneca PLC This announcement contains information that AstraZeneca PLC is obliged to make public pursuant to the EU Market Abuse Regulation (596/2014) and the assimilated EU Market Abuse Regulation (596/2014) as it forms part of the law of the United Kingdom by operation of the European Union (Withdrawal) Act 2018. This announcement was submitted for publication, through the agency of the contact person(s) set out above, at 21:15 BST 11 September 2026. tags

Phase 3Drug ApprovalImmunotherapyClinical ResultADC

100 Deals associated with Tamoxifen Citrate

External Link

KEGG	Wiki	ATC	Drug Bank
D00966	Tamoxifen Citrate	L02BA01	DB00675

R&D Status

Approved

10 top approved records.

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Indication	Country/Location	Organization	Date
Estrogen receptor positive breast cancer	United States	Mayne Pharma Commercial LLC	25 Sep 2018
Noninfiltrating Intraductal Carcinoma	United States	Mayne Pharma Commercial LLC	29 Oct 2005
Breast Cancer	United States	AstraZeneca Pharmaceuticals LP	30 Dec 1977

Developing

10 top R&D records.

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Indication	Highest Phase	Country/Location	Organization	Date
Gynecomastia	Phase 3	Italy	AstraZeneca PLC	01 Dec 2003
Prostatic Cancer	Phase 3	Italy	AstraZeneca PLC	01 Dec 2003
Invasive Mammary Carcinoma	Phase 3	-	AstraZeneca PLC	01 Jul 1996
Hormone receptor positive breast cancer	Phase 3	Austria	AstraZeneca PLC	01 Jan 1996
Early Stage Breast Carcinoma	Phase 3	-	AstraZeneca PLC	01 Dec 1990
Vulvovaginal atrophy	Phase 2	Australia	Daré Bioscience, Inc.	22 Nov 2021
Dementia	Phase 2	United States	AstraZeneca PLC	01 Jan 2007
Dementia	Phase 2	Italy	AstraZeneca PLC	01 Jan 2007
Metastatic Neoplasm to the Bladder	Phase 2	United States	AstraZeneca PLC	01 Jan 2007
Metastatic Neoplasm to the Bladder	Phase 2	Italy	AstraZeneca PLC	01 Jan 2007

Clinical Result

Indication

Phase

Evaluation

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Study	Phase	Population	Analyzed Enrollment	Group	Results	Evaluation	Publication Date


NCT04570956 (CTgov)	Phase 2	Atypical lobular hyperplasia \| Breast Carcinoma in Situ \| Atypical Lobular Breast Hyperplasia ... View more	65	Questionnaire Administration+Tamoxifen (Oral Tamoxifen 10 mg/Day)	huvukahcsh(cvjfaycgwg) = fvzbdvdkfo swsfbavzjs (hsekohwjza, bseautdwpt - kucsjyeuzj) View more	-	01 Sep 2026
				Questionnaire Administration+Topical 4-OHT( 4-hydroxytamoxifen)gel 4 mg/each breast/day (Topical 4-OHT (4-hydroxytamoxifen) Gel 4 mg/Each Breast/Day)	huvukahcsh(cvjfaycgwg) = ebnwtpvknb swsfbavzjs (hsekohwjza, cddxtwoojm - lbzfxvkqdn) View more
NCT02206984 (P3-05-14 \| TBCRC037, CTgov)	Phase 2	Invasive Lobular Breast Carcinoma	201	fulvestrant (Fulvestrant)	btzgeqzklj(guuufgvyiu) = isdjmtdewq zldpdubwoo (fpepvnvpuk, 1.1) View more	-	07 Aug 2026
				anastrozole (Anastrozole)	btzgeqzklj(guuufgvyiu) = coogdhhcjj zldpdubwoo (fpepvnvpuk, 1.1) View more
NCT06982313 (Pubmed \| J Clin Oncol)	Not Applicable	Neoplasms	1,545	Low-dose tamoxifen	lejmfljgix(szzgtcjmef): HR = 0.45 (95.0% CI, 0.26 - 0.76) View more	Positive	01 Aug 2026
				Placebo
NCT00053898 (NSABP B-35, Pubmed \| JAMA Surg)	Phase 3	Noninfiltrating Intraductal Carcinoma hormone receptor (HR)-positive	3,104	Tamoxifen	zoldjcasva(xwlaqjzyiu) = xyomvqjaqm kqnxbwfbax (pqleayxdgo ) View more	Positive	01 Jul 2026
				Anastrozole	zoldjcasva(xwlaqjzyiu) = whonxfeedr kqnxbwfbax (pqleayxdgo ) View more
NCT06982313 (ASCO2026)	Not Applicable	Breast Carcinoma in Situ \| Noninfiltrating Intraductal Carcinoma \| Inappropriate ADH Syndrome	1,772	Low-dose tamoxifen (Babytam)	qffnkvfwfn(eurvfhshiz) = fmoyjritgw iqeleaiepq (jxmpccfajp ) View more	Positive	29 May 2026
				Placebo	qffnkvfwfn(eurvfhshiz) = xukyfuxyyk iqeleaiepq (jxmpccfajp ) View more
NCT03346200 (KARISMA Tamoxifen, ESMO_BC2026)	Phase 2	-	585	Tamoxifen 5 mg	fxgkbfdqgl(jwbznxgzmo) = zuwenxqatm rngutyndnz (tinecxwwev ) View more	Positive	07 May 2026
NCT04292886 (Pubmed \| Int J Gen Med)	Phase 3	-	120	Tamoxifen Combined with Hormone Replacement	veshhjonrh(qqbaprdexe) = yawzifqiso iuuihcslbr (hzlasdegyq, 0.93)	Positive	01 May 2026
				Hormone Replacement	veshhjonrh(qqbaprdexe) = bgnnskjtiq iuuihcslbr (hzlasdegyq, 0.8)
NCT03354039 (TAMDMD, Pubmed \| Neuromuscul Disord)	Phase 3	Muscular Dystrophy, Duchenne	66	Delayed tamoxifen treatment group	ppuqsjgfos(rjltrjiqpp) = pldgtfpfmb speqneugxs (diawaxrlli )	Negative	01 Apr 2026
POSITIVE (ESGO2026)	Not Applicable	Hormone receptor positive breast cancer hormone receptor-positive (HR+)	974	Paused tamoxifen	ypsnxragei(tquazrzwne) = pwhrbdwzkb kboirduvkq (dyivxtjjgp ) View more	Positive	28 Feb 2026
				Tamoxifen users (Retrospective cohort)	ghkorjpxrt(dauodqzzjj) = ydhcxhhkbj zygfvheosw (bqhsjypfaj ) View more
NCT05101564 (CTgov)	Phase 2	ER-positive/HER2-negative Breast Cancer \| HER2-negative breast cancer \| Estrogen receptor positive breast cancer	19	Fulvestrant+Zotatifin (Cohort 2: Zotatifin in Combination With Fulvestrant (Treatment Arm))	lpmxpeoeia(thebcjzrjc) = rfyrcmmthd jaaiwivwro (jnltcloyhi, uthsuqrgpv - mpkaaareuu) View more	-	22 Jan 2026
				Fulvestrant (Cohort 2: Fulvestrant (Control Arm))	lpmxpeoeia(thebcjzrjc) = qmugjijqtz jaaiwivwro (jnltcloyhi, ayvvzswwbm - fjjjgyswpn) View more

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