---
title: "Atossa says novel endoxifen-related compounds show potent preclinical activity in ER-positive breast cancer models"
type: "News"
locale: "en"
url: "https://longbridge.com/en/news/294066238.md"
description: "Atossa Therapeutics reported that five novel (Z)-endoxifen-related compounds demonstrated potent preclinical activity in ER-positive breast cancer models. The study highlighted anti-estrogenic effects, efficacy in ESR1-mutant models associated with endocrine resistance, and synergistic results when combined with abemaciclib. These candidates are being positioned as potential second- or third-line treatments, pending further in vivo safety and efficacy studies."
datetime: "2026-07-28T12:30:34.000Z"
locales:
  - [zh-CN](https://longbridge.com/zh-CN/news/294066238.md)
  - [en](https://longbridge.com/en/news/294066238.md)
  - [zh-HK](https://longbridge.com/zh-HK/news/294066238.md)
generator: "portal-rs"
---

# Atossa says novel endoxifen-related compounds show potent preclinical activity in ER-positive breast cancer models

-   Atossa Therapeutics highlighted a peer-reviewed preclinical npj Breast Cancer study on five novel (Z)-endoxifen-related compounds in ER-positive breast cancer models. \* Several candidates showed anti-estrogenic activity across tumor-growth assays, apoptosis, cell-cycle effects, migration, invasion, estrogen receptor transcription, gene-expression changes. \* Selected compounds retained activity in ESR1-mutant models tied to endocrine resistance in recurrent or metastatic disease. \* Combinations with CDK4/6 inhibitor abemaciclib produced additive-to-synergistic effects, matching or exceeding abemaciclib with (Z)-endoxifen in some settings. \* Authors flagged select candidates for in vivo safety work, then efficacy studies, positioning them as potential second- or third-line approaches; results remain preclinical. Disclaimer: This news brief was created by Public Technologies (PUBT) using generative artificial intelligence. While PUBT strives to provide accurate and timely information, this AI-generated content is for informational purposes only and should not be interpreted as financial, investment, or legal advice. Atossa Therapeutics Inc. published the original content used to generate this news brief via PR Newswire (Ref. ID: 202607280830PR\_NEWS\_USPR\_\_\_\_\_SF13421) on July 28, 2026, and is solely responsible for the information contained therein. © Copyright 2026 - Public Technologies (PUBT)

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> **Disclaimer: This article is for reference only and does not constitute any investment advice.**