Spero Therapeutics Announces First Quarter 2025 Operating Results and Provides a Business Update (Form 8-K)

Pre-specified interim analysis of the ongoing Phase 3 PIVOT-PO clinical trial of tebipenem HBr in complicated urinary tract infection (cUTI), including acute pyelonephritis (AP), on track to be completed in Q2 2025

Existing cash, together with earned development milestones from GSK, provide runway to fund operating expenses and capital expenditures into Q2 2026

Together with GSK, we are conducting a pre-specified interim analysis of the Phase 3 PIVOT-PO clinical trial of tebipenem HBr. This pre-specified interim analysis is expected in Q2 2025.

This randomized, double-blind clinical trial compares oral tebipenem HBr with intravenous imipenem-cilastatin, in hospitalized adult patients with cUTI/AP. The primary endpoint is overall response (a combination of clinical cure and favorable microbiological response) at the Test-of-Cure (TOC) visit. For more information on our PIVOT-PO trial, please refer to ClinicalTrials.gov ID NCT06059846.

The oral development program in NTM-PD was suspended in 4Q 2024. This followed a planned interim analysis of 16 patients dosed in the Phase 2a study, which demonstrated the study did not meet its primary endpoint.

The Company is currently completing analysis of the data from all 25 patients dosed in the Phase 2a proof-of-concept study in NTM-PD and plans to determine next steps for the program.

Esther Rajavelu was appointed as Spero's President and Chief Executive Officer, effective May 2, 2025. Ms. Rajavelu has also been nominated for election to the Board of Directors at Spero's 2025 annual meeting of stockholders. She will continue to serve as the Company's Chief Financial Officer and Treasurer.

Spero reported a net loss of $(13.9) million for the first quarter of 2025 compared to a net loss of $(12.7) million for the first quarter of 2024, or a diluted net loss and net income per share of common stock of $(0.25) and $(0.24), respectively.

Total revenue for the first quarter of 2025 was $5.9 million, compared with total revenue of $9.3 million for the first quarter of 2024. The revenue decrease for the first quarter of 2025 was primarily due to a decrease in grant revenue, offset by higher collaboration revenue related to our agreement with GSK.

Research and development expenses for the first quarter of 2025 were $13.6 million, compared to $17.3 million of research and development expenses for the same period in 2024. The decrease in research and development expenses compared with the prior year period was primarily due to lower expenditure on the SPR720 clinical program.

General and administrative expenses for the first quarter of 2025 were $6.8 million, compared to $5.9 million of general and administrative expenses for the same period in 2024. This increase compared with the prior year period was primarily due to an increase in personnel-related costs, as well as an increase consulting and professional fees.

As of March 31, 2025, Spero had cash and cash equivalents of $48.9 million. Spero estimates that its existing cash and cash equivalents, together with upcoming $23.75M of earned and non-contingent development milestone payments from GSK will be sufficient to fund its operating expenses and capital expenditures into Q2 2026.