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.

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