Atossa presents preclinical data on breast cancer drug at ASCO
Atossa Therapeutics Inc announced today that two abstracts on its experimental drug (Z)-endoxifen have been accepted for presentation at the 2026 American Society of Clinical Oncology Annual Meeting, scheduled for May 29 to June 2 in Chicago.
Preclinical Findings on ESR1 Mutations
The first abstract presents preclinical data showing (Z)-endoxifen inhibited estrogen receptor signaling in breast cancer models with ESR1 mutations, according to a press release statement.In MCF-7 breast cancer cells, the drug reduced ER activity to 16-26% of control levels.The data showed the compound maintained inhibition across Y537N, Y537S, and D538G mutations.
The preclinical study compared (Z)-endoxifen to oral Selective Estrogen Receptor Degraders elacestrant and imlunestrant in ESR1-mutant settings.ESR1 mutations occur in patients with advanced ER-positive breast cancer following endocrine therapy and are associated with treatment resistance.
Updates on the EVANGELINE Phase 2 Study
The second abstract describes EVANGELINE (NCT05607004), an ongoing Phase 2 study evaluating (Z)-endoxifen at 40 mg daily plus goserelin administered every 28 days as neoadjuvant therapy in premenopausal women with ER-positive/HER2-negative, cT2-3, cN0-1 breast cancer.The study’s primary objective is to determine the proportion of patients with baseline Ki-67 above 10% who achieve Ki-67 of 10% or less after four weeks of therapy.
The trial uses a Simon two-stage design with 20 patients in the first stage and potentially 25 additional patients in the second stage.A parallel cohort of 20 patients with baseline Ki-67 of 10% or less will assess objective response rate at 24 weeks.Phase 2 enrollment opened in May 2025.
Corporate and Financial Developments
Atossa is a clinical-stage biopharmaceutical company with a market capitalization of $42.63 million.According to InvestingPro data, the company holds more cash than debt on its balance sheet and maintains liquid assets that exceed short-term obligations, though it is quickly burning through cash and is not expected to be profitable this year. The stock has faced significant headwinds, declining 57.68% over the past six months and trading at $4.95, well below its 52-week high of $19.35.Despite these challenges, analysts maintain a positive outlook with price targets ranging from $20 to $25, and InvestingPro analysis suggests the stock is currently undervalued relative to its Fair Value.
In other recent news, Atossa Therapeutics Inc. has released results from its Phase 2 trial of endoxifen, showing a reduction in mammographic breast density among participants.This development was published in the Journal of the National Cancer Institute and involved 240 healthy premenopausal women in Sweden.Additionally, the U.S. Food and Drug Administration granted a Rare Pediatric Disease designation to Atossa’s (Z)-endoxifen for treating McCune-Albright Syndrome in females.This designation allows Atossa to qualify for a Priority Review Voucher upon approval, which can be used for expedited reviews or sold to other sponsors, with recent sales ranging from $100 million to $205 million.
Moreover, Atossa has reached a settlement agreement with Intas Pharmaceuticals Ltd. and Jina Pharmaceuticals, Inc. to resolve patent disputes related to Endoxifen intellectual property.This agreement aims to terminate ongoing proceedings before the U.S. Patent and Trademark Office Patent Trial and Appeal Board.In analyst news, H.C. Wainwright has raised its price target for Atossa’s stock to $25 from $7, maintaining a Buy rating on the shares.The adjustment follows a 1-for-15 reverse stock split executed by the company.These developments highlight significant progress and strategic movements for Atossa Therapeutics in recent times.
