Benzinga | Jun 9, 2021 01:29PM EDT

Atossa Therapeutics Reveals Final Endoxifen Data From Mid-Stage Breast Cancer Trial

* Atossa Therapeutics Inc (NASDAQ:ATOS) has announced final data from its Phase 2 study of oral Endoxifen administered between the diagnosis of breast cancer and surgery.

* The study enrolled seven newly-diagnosed patients with ER+ and human epidermal growth factor receptor 2 negative (HER2-) stage 1 or 2 invasive breast cancer, requiring mastectomy or lumpectomy.

* Patients received oral Endoxifen for at least 14 days from the time of diagnosis up to the day of surgery.

* Results showed a 65.1% reduction in Ki-67, a measure of tumor cell activity, from an average of 25.6% at the screening to 6% on the day of surgery.

* Ki-67 was reduced below 25% for all patients, potentially clinically meaningful because studies by others have shown that a reduction below 25% improves long-term survival.

* All adverse events were mild and considered related to the study drug.

* No abnormal laboratory findings and no differences in vital signs, physical examinations, and ECGs were observed.

* Estrogen receptor expression decreased from 100% at the screening to 88.6% on the day of surgery, and progesterone receptor expression increased from 84.3% at the screening to 92.9% on the day of surgery.

* No correlation between Ki-67 expression and Endoxifen levels was observed.

* Price Action: ATOS shares are down 26.9% at $4.44 during the market session on the last check Wednesday.