Spero Therapeutics Halts SPR720, Reduces Workforce Amid Financial Restructuring

Spero Therapeutics has encountered a significant obstacle with its SPR720 program after the candidate failed to meet expectations in a Phase IIa trial. The interim analysis indicated that the antibiotic, aimed at treating nontuberculous mycobacterial pulmonary disease, did not achieve the primary endpoint and showed concerning safety issues, such as reversible grade 3 hepatotoxicity. This outcome has led Spero to halt the SPR720 development program and implement a substantial workforce reduction, laying off approximately 39% of its employees, all in an effort to extend its financial runway into mid-2026[1][2].