Atossa Therapeutics, Inc. 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.