Spero Therapeutics, Inc.

Forward-Looking Statements

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended. Forward-looking statements include, but are not limited to, statements relating to Spero’s plans to advance SP001 into a Phase 2 study in IgG4-related disease; Spero’s plans to explore the use of SP001, and the role of CD40L inhibition, in additional autoimmune and inflammatory diseases; the anticipated benefits of thenon-dilutive royalty-backed transaction, including the anticipated use of proceeds; Spero’s expectation that Utebzi will be made available to U.S. patients by the end of 2026; anticipated cash runway, and future milestones. Forward-looking statements are based on Spero’s current expectations and assumptions and are subject to risks and uncertainties that could cause actual results to differ materially from those expressed or implied by such statements. These risks and uncertainties include, among others, risks related to the completion and integration of the Innovent transaction; Spero’s ability to successfully develop SP001; the timing and outcome of clinical trials and regulatory interactions; the ability to obtain and maintain regulatory approvals; potential safety, efficacy, manufacturing, supply, intellectual property, financing, competitive, and market risks; and other risks described in Spero’s filings with the Securities and Exchange Commission. Spero undertakes no obligation to update any forward-looking statements, except as required by law.