Atossa Therapeutics Inc Stock Price, News & Analysis

Atossa Therapeutics (NASDAQ: ATOS) announced that the U.S. Food and Drug Administration Office of Orphan Products Development has granted Orphan Drug Designation to (Z)-endoxifen for the treatment of Duchenne muscular dystrophy (DMD) on January 16, 2026. This designation follows a previously received Rare Pediatric Disease designation and supports continued development of (Z)-endoxifen in this rare pediatric neuromuscular disorder. The company said it will continue engaging with the FDA as it advances development efforts and will provide updates as appropriate.

Atossa Therapeutics (Nasdaq: ATOS) announced on January 6, 2026 that the U.S. Food and Drug Administration issued a "Study May Proceed" letter for its investigational new drug application for (Z)-endoxifen in metastatic ER+/HER2- breast cancer.

The company presented this as a regulatory milestone to advance a clinical study testing (Z)-endoxifen's activity, including in tumors with resistance to other endocrine therapies and targeting the oncogenic signaling pathway PKCβ1. No clinical efficacy or safety results were reported in this announcement.

Atossa Therapeutics (Nasdaq: ATOS) was named a winner of the 2025 Clinical Trials Arena Research and Development Excellence Award in the Precision Endocrine Therapy category on December 17, 2025.

The company was honored for advancing (Z)-endoxifen, a precision-engineered SERM/D with PKCβ1 inhibition intended to provide consistent systemic exposure independent of CYP2D6 metabolism. (Z)-endoxifen is being evaluated across metastatic, neoadjuvant, adjuvant, and risk-reduction breast cancer settings, with an emerging application in Duchenne muscular dystrophy. The award recognizes scientific rigor and innovation in clinical research and development.

Atossa Therapeutics (Nasdaq: ATOS) presented four clinical updates at SABCS 2025 on (Z)-endoxifen, covering DCIS active surveillance, low-dose I-SPY2 pilot data, ESR1-mutant mechanistic results, and the Phase 2 EVANGELINE neoadjuvant trial.

Key facts: daily 10 mg (Z)-endoxifen was well tolerated with 95% of patients completing ≥75% therapy; MRI tumor volume median change was -72%; ctDNA clearance occurred in 70% of initially positive patients; EVANGELINE run-in showed 86% with Week 4 Ki-67 ≤10% supporting a 40 mg Phase 2 dose.

Atossa Therapeutics (Nasdaq: ATOS) announced on December 11, 2025 that the U.S. FDA granted Rare Pediatric Disease (RPD) designation to (Z)-Endoxifen for the treatment of Duchenne Muscular Dystrophy (DMD). RPD designation targets therapies for serious diseases affecting patients birth to 18 and can make a drug eligible for a Priority Review Voucher (PRV) upon approval. The release cites disclosed PRV sales in the last 18–24 months ranging from $100–$160 million. Company statements note enhanced FDA interaction to define a DMD clinical path, emerging preclinical data supporting (Z)-Endoxifen as a potent SERM/D, and plans to advance the program to the clinic as a potentially broader, exon-agnostic DMD approach.

Atossa Therapeutics (Nasdaq: ATOS) announced that the USPTO issued U.S. Patent No. 12,479,790 B2 on Dec 9, 2025, titled "Methods for Making and Using Endoxifen."

The patent includes 100 claims covering enteric oral formulations of highly pure (Z)-endoxifen free base, specific solid oral dosage forms, scalable manufacturing processes, and methods of use for hormone-dependent breast disorders and other estrogen-related conditions. The company says this grant adds to its existing U.S. patents and worldwide applications to support late-stage trials and potential commercialization of (Z)-endoxifen across prevention and treatment settings.

Atossa Therapeutics (Nasdaq: ATOS) completed a Type C meeting with the FDA on November 17, 2025 to review regulatory strategy for (Z)-endoxifen. The FDA provided feedback on potential expedited pathways and development options across metastatic, neoadjuvant ER+/HER2-, and breast cancer risk-reduction settings, focusing on clinical design, endpoints, and streamlined registrational approaches. Atossa said FDA input clarified routes to accelerate development and regulatory review.

Key program items: a metastatic dose-ranging study is in preparation and an IND was submitted for the metastatic program (awaiting feedback); the Phase 2 EVANGELINE neoadjuvant trial is enrolling; risk-reduction work targets low-dose effects on mammographic density. Atossa reported completing multiple trials involving nearly 800 participants and expects additional INDs in 2026.

Atossa Therapeutics (Nasdaq: ATOS) and Insilico Medicine published a joint AI-driven study in Nature Scientific Reports on Dec 2, 2025 identifying (Z)-endoxifen as a potential therapeutic candidate for glioblastoma (GBM).

The study used Insilico's PandaOmics across >900 cancer indications and multi-omic methods, ranked GBM as a top opportunity, found >1,400 shared genes reversed by endoxifen, and reported in vitro suppression of GBM cell proliferation exceeding high-dose temozolomide plus tolerable in vivo dosing. Insilico also cited 20 preclinical nominations with a 12–18 month average turnaround.

Atossa (Nasdaq: ATOS) highlighted a newly published peer‑reviewed hypothesis article and an invited scientific presentation supporting the investigational therapy (Z)-endoxifen for Duchenne muscular dystrophy (DMD) and symptomatic female carriers (D‑CAPs).

The paper maps multi‑pathway mechanisms — ER modulation, PKC‑β1 inhibition, AKT/mTOR and NF‑κB effects — and notes potential advantages over tamoxifen due to more consistent exposure. Atossa plans preclinical validation and fit‑for‑purpose clinical studies focused on safety, PK/PD, functional and cardiac endpoints; a follow‑up manuscript on utrophin modulation is under review.