Exhibit 99.1 Atossa Therapeutics Announces Year-End 2023 Financial Results and Provides Corporate Update • Fully enrolled two Phase 2 studies with data from both expected in the second half of 2024 • First patient dosed in new Phase 2 breast cancer prevention study • Data from ongoing Phase 2 EVANGELINE study scheduled to be presented at 2024 AACR Annual Meeting • Ended 2023 with $88.5 million of cash and cash equivalents and no debt SEATTLE, April 1, 2024— Atossa Therapeutics, Inc. (Nasdaq: ATOS) ("Atossa" ...