SPRO · Spero Therapeutics, Inc.

Spero Therapeutics announced first quarter 2026 results showing significant improvement in net loss to $7.2 million from $13.9 million year-over-year, primarily due to sharply reduced research and development expenses of $2.9 million versus $13.6 million in Q1 2025. This decline stemmed from decreased clinical activities after the tebipenem HBr Phase 3 PIVOT-PO trial was stopped early for efficacy in May 2025, alongside lower personnel costs. General and administrative expenses also fell to $4.9 million from $6.8 million, reflecting reduced legal and personnel-related spending. Revenue dropped to $0.3 million from $5.9 million, tied to lower collaboration revenue from GSK. Balance sheet remains solid with $56.1 million in cash and equivalents as of March 31, 2026, up from year-end 2025, supporting operations into 2028 without near-term dilution risk. The highlight is the tebipenem HBr NDA under FDA review, submitted by GSK in December 2025 with PDUFA target of June 18, 2026. The oral carbapenem demonstrated non-inferiority to IV imipenem-cilastatin in cUTI patients, with a favorable safety profile of mostly mild diarrhea and headache. CEO Esther Rajavelu emphasized progress with GSK and plans to expand the clinical-stage portfolio, positioning Spero for potential milestone payments and commercialization if approved.