Atossa Therapeutics Announces Last Patient, Last Dose in its Phase 2 Karisma-Endoxifen Clinical Trial

SEATTLE, May 15, 2024 (GLOBE NEWSWIRE) -- Atossa Therapeutics, Inc. (Nasdaq: ATOS) (“Atossa” or the “Company”) today announced that the last patient in the Company’s Karisma-Endoxifen clinical trial received their final dose of study medication. Atossa is a clinical stage biopharmaceutical company developing innovative medicines in areas of significant unmet medical need in oncology with a focus on breast cancer.

The Karisma-Endoxifen study, which fully enrolled in November 2023, is a 240-person Phase 2 clinical trial investigating (Z)-endoxifen in premenopausal women with measurable mammographic breast density (MBD). Participants were randomized to placebo, 1 mg, and 2 mg daily doses of (Z)-endoxifen and treated for six months, over the course of which mammograms are conducted to measure reduction in MBD. Medication-induced MBD reduction has been associated with a 50% to 63% reduction in the incidence of breast cancer in a three-to-fifteen-year follow-up period.

Approximately half of all women are estimated to have mammographically dense breasts, which makes mammography less sensitive and mammograms more difficult to interpret, since cancer and dense breast tissue both appear white on a mammogram. Women with the highest density are up to six-times more likely to develop breast cancer in their lifetime compared to women with the lowest density. Additionally, in this patient population, approximately 50% of all breast cancers are missed on a mammogram and diagnosed in the interval between two screening rounds. These tumors, which are known as interval cancers, are often larger, more advanced, and more difficult to treat.

“Completing dosing of the final patient in the Karisma-Endoxifen study is an important milestone for Atossa and our robust (Z)-endoxifen development program, which includes five ongoing Phase 2 studies,” said Steven Quay, M.D., Ph.D., Atossa’s President and Chief Executive Officer. “We look forward to seeing the breast density reduction data in the coming months and sharing it with regulatory authorities as it will allow us to further progress plans for a potential Phase 3, registrational study.”

About (Z)-Endoxifen
(Z)-endoxifen is the most potent Selective Estrogen Receptor Modulator (SERM) for estrogen receptor inhibition and also causes estrogen receptor degradation. It has also been shown to have efficacy in the setting of patients with tumor resistance to other hormonal treatments. In addition to its potent anti-estrogen effects, (Z)-endoxifen has been shown to target PKCβ1, a known oncogenic protein, at clinically attainable blood concentrations. Finally, (Z)-endoxifen appears to deliver similar or even greater bone agonistic effects while resulting in little or no endometrial proliferative effects compared with standard treatments, like tamoxifen.