---
schema_version: "secwatch.filing_event.v1"
accession: "0000950170-24-120268"
form_type: "8-K"
ticker: "ATOS"
cik: "0001488039"
company_name: "ATOSSA THERAPEUTICS, INC."
filed_at: "2024-11-04T23:59:59+00:00"
generated_at: "2026-05-30T05:59:11.061172+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.7
calibrated_materiality_score: 0.7
confidence: "high"
source: SEC EDGAR
---

# Atossa reports positive Phase 2 data for (Z)-endoxifen reducing breast density by up to 26.5%

## Summary
- Relative MBD reduction of 19.3% (1 mg) and 26.5% (2 mg) vs placebo in KARISMA-Endoxifen trial.
- Mean plasma endoxifen: 5.18 ng/mL (1 mg) and 10.87 ng/mL (2 mg) after 1 month; stable at 3 and 6 months.
- Drug-related discontinuations: 4 placebo, 5 (1 mg), 12 (2 mg); vasomotor symptoms minimal on 10-point scale.
- Historical tamoxifen study: 10%+ density reduction associates with 62% lower 5-year breast cancer incidence.
- Detailed results to be presented at San Antonio Breast Cancer Symposium in December 2024.

## SEC filing metadata
- accession: 0000950170-24-120268
- form_type: 8-K
- ticker: ATOS
- cik: 0001488039
- company_name: ATOSSA THERAPEUTICS, INC.
- filed_at: 2024-11-04T23:59:59+00:00
- event_type: other_material
- sentiment: positive
- materiality_score: 0.7
- calibrated_materiality_score: 0.7
- confidence: high
- sec_items: 8.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1488039/000095017024120268/0000950170-24-120268-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1488039/000095017024120268/atos-20241104.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0000950170-24-120268
- JSON: https://secwatch.observer/filing/0000950170-24-120268.json
- Plain text: https://secwatch.observer/filing/0000950170-24-120268.txt

This AI-assisted summary is a reading aid. Review the linked SEC EDGAR filing before relying on any specific claim.