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ATOS Atossa Therapeutics

Atossa Therapeutics Inc is a clinical-stage biopharmaceutical company engaged in the development of proprietary medicines for oncology, with a focus on breast cancer and related conditions. The company's lead product candidate, oral (Z)-endoxifen, is a selective estrogen receptor modulator and degrader (SERM/SERD) in P…

Assets on file: (Z)-endoxifen

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Catalyst calendar

Dated catalysts for ATOS, including recently decided ones.

November 2026

Nov 2026

~ Nov 2026

ATOSAtossa Therapeutics

(Z)-endoxifen: Phase 2 trial NCT05607004 expected to finish collecting primary-endpoint data (topline results usually follow)

Trial primary completionClinicalTrials.govMonth only

November 2028

Nov 2028

~ Nov 2028

ATOSAtossa Therapeutics

(Z)-endoxifen: Phase 2 trial NCT06075953 expected to finish collecting primary-endpoint data (topline results usually follow)

Trial primary completionClinicalTrials.govMonth only

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Material

Jan 6, 2026

01:30 PM

ATOSAtossa Therapeutics

Atossa receives FDA Study May Proceed letter for (Z)-endoxifen in metastatic breast cancer

FDA cleared the IND application for (Z)-endoxifen in metastatic ER+/HER2- breast cancer, allowing the company to initiate the planned clinical study. This regulatory green-light advances the program into the next stage of clinical development.

OtherSEC 8-K Open record

Notable

Dec 4, 2025

01:15 PM

ATOSAtossa Therapeutics

Atossa completes FDA Type C meeting on (Z)-endoxifen regulatory strategy

Atossa held a Type C meeting with the FDA on November 17, 2025, receiving feedback on expedited regulatory pathways for (Z)-endoxifen across metastatic, neoadjuvant, and risk-reduction settings. The Company plans to incorporate this feedback to accelerate development timelines and pursue streamlined registrational approaches. An IND for metastatic breast cancer has been submitted and is awaiting feedback.

Conference presentationSEC 8-K

Material

Nov 12, 2025

01:40 PM

ATOSAtossa Therapeutics

Atossa Therapeutics schedules FDA Type C meeting for (Z)-endoxifen

Atossa requested and received preliminary FDA comments for a Type C meeting on November 17, 2025 to discuss regulatory strategy for accelerating (Z)-endoxifen development in breast cancer risk reduction. The meeting aims to align on NDA requirements and potential expedited programs, with meeting minutes expected in December 2025.

Advisory committee scheduledSEC 8-K Open record