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Atossa Therapeutics Receives FDA "Study May Proceed" Letter for (Z)-Endoxifen Investigational New Drug Application for Metastatic Breast Cancer
SEATTLE, Jan. 6, 2026 /PRNewswire/ -- Atossa Therapeutics, Inc. (Nasdaq: ATOS), a clinical-stage biopharmaceutical company developing innovative medicines for
About this update from Atossa Therapeutics, Inc.
[{"type":"text","content":"SEATTLE, Jan. 6, 2026 /PRNewswire/ -- Atossa Therapeutics, Inc. (Nasdaq: ATOS), a clinical-stage biopharmaceutical company developing innovative medicines for unmet medical needs, today announced that the U.S. Food and Drug Administration (\"FDA\") issued a \"Study May Proceed\" letter for the Company's study in metastatic breast cancer which was the subject of a recent investigational new drug application for (Z)-endoxifen.\n \n \n \n \n \n \n \n\"This letter marks an important regulatory milestone for Atossa and to potentially expand the use of (Z)-endoxifen for metastatic ER+/HER2- Breast Cancer. We believe its activity, even in tumors that have developed resistance to other endocrine therapies and in the oncogenic signaling pathway, protein kinase C beta 1 (PKCĪ²1), may offer a new tool in treating this disease.,\" said Dr. Steven Quay, M.D., Ph.D., Atossa Therapeutics President and Chief Executive Officer. \"We appreciate the FDA's review and look forward to advancing this clinical investigation.\"About (Z)-Endoxifen(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.About Atossa TherapeuticsAtossa 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. More information is available at https://atossatherapeutics.com.Forward-Looking StatementsThis 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, the potential indications that the ...