Exhibit 99.1 Spero Therapeutics Announces First Quarter 2024 Operating Results and Provides a Business Update • On track for topline data from SPR720 Phase 2a proof-of-concept trial in treatment-naive and treatment-experienced non-refractory NTM-PD patients, expected in 2H 2024 • Enrollment ongoing in PIVOT-PO, a pivotal Phase 3 clinical trial of oral tebipenem HBr in cUTI • Received FDA Fast Track designation for SPR206 for treatment of HABP/VABP due to CRABc and CRPA • Cash balance of $82.3 million as of ...