Spero Therapeutics, Inc. (NASDAQ:SPRO) saw its stock soar by 240% after announcing highly encouraging results from its Phase 3 PIVOT-PO trial, conducted in collaboration with development partner GSK plc (LSE/NYSE: GSK). The trial assessed tebipenem HBr, an investigational oral carbapenem antibiotic aimed at treating complicated urinary tract infections (cUTIs).
The study, which enrolled 1,690 patients, was halted early due to positive efficacy results, based on recommendations from an Independent Data Monitoring Committee (IDMC). The trial achieved its primary goal, showing that tebipenem HBr was non-inferior to IV-administered imipenem-cilastatin in treating hospitalized adults with cUTI, including pyelonephritis. The most common side effects reported were diarrhea and headache, with no new safety concerns identified.
According to the company’s May 28, 2025 press release, tebipenem HBr has the potential to become the first oral carbapenem antibiotic approved for use in the U.S., targeting an estimated 2.9 million cUTI cases annually. These infections are a major driver of hospitalizations and contribute over $6 billion in healthcare costs each year.
“This is a significant milestone for Spero,” said CEO Esther Rajavelu. “We believe tebipenem HBr has the potential to transform how cUTIs and pyelonephritis are treated.”
GSK’s Chief Scientific Officer, Tony Wood, also underscored the broader implications, noting, “Complicated UTIs can significantly burden patients and the healthcare system, especially when oral treatment options for drug-resistant infections are limited.”
Spero and GSK plan to present full trial data at an upcoming scientific meeting and will submit it for peer-reviewed publication. They also intend to file with the FDA in the second half of 2025. The project has received partial funding from the U.S. Department of Health and Human Services, including BARDA, under contract HHSO100201800015C.