GSK's $66M Investment in Spero's Rejected UTI Antibiotic Succeeds in Phase 3

GSK has achieved a significant milestone in the field of antibiotic development, particularly targeting complicated urinary tract infections (cUTIs). The FDA has recently approved Blujepa, marking a regulatory triumph for the pharmaceutical giant. This achievement stems from GSK's strategic decision to acquire and advance Spero Therapeutics' antibiotic candidate, tebipenem HBr, three years ago. The decision has proven fruitful based on promising phase 3 trial results.

The phase 3 trial, involving 1,690 patients hospitalized due to cUTIs, was concluded ahead of schedule. The early halt was due to clear indications that tebipenem HBr would successfully meet the primary endpoint, demonstrating its non-inferiority to the intravenous antibiotic treatment with imipenem/cilastatin. With these positive results, GSK is poised to seek an FDA review within the year. Should the approval be granted, tebipenem HBr will emerge as the first oral carbapenem antibiotic available to U.S. patients suffering from complicated UTIs.

Complicated UTIs can have severe repercussions for patients, posing significant risks such as sepsis and septic shock. As noted by GSK's Chief Scientific Officer, Tony Wood, Ph.D., these infections necessitate hospital-based intravenous treatments due to limited oral drug options for resistant infections. This situation contributes to an annual healthcare cost exceeding $6 billion in the U.S. The promising phase 3 outcomes offer hope for an effective oral alternative that patients can take at home, potentially easing the burden on healthcare systems.

GSK’s journey with tebipenem HBr began in 2022 when the company saw potential despite the FDA's previous rejection of Spero's application for approval. The upfront payment of $66 million from GSK enabled Spero Therapeutics to fund the pivotal phase 3 trial. Spero’s CEO, Esther Rajavelu, emphasized the importance of achieving the primary endpoint in the trial, describing it as a significant milestone for tebipenem HBr. If approved, the oral antibiotic could revolutionize treatment strategies for patients diagnosed with cUTIs, including pyelonephritis.

This late-stage success is a much-needed boost for Spero Therapeutics, particularly after a challenging year marked by workforce reductions and a narrowed pipeline. Among the challenges faced was the discontinuation of work on SPR720, another oral antibiotic, after it failed to outperform placebo and exhibited liver toxicity signs during a phase 2 trial for non-tuberculous mycobacterial pulmonary disease.

Despite the low return on investment that has deterred many major biopharmaceutical companies from pursuing new antifungal or antibiotic ventures, GSK has continued to forge ahead. The corporation has consistently engaged in strategic deals and has reported promising clinical outcomes against various infections, including gonorrhea.

GSK's dedication to advancing antibiotic solutions, particularly oral options for complicated infections, underscores its commitment to addressing significant healthcare challenges. The potential FDA approval for tebipenem HBr would not only mark a triumph for GSK but could also transform the clinical management of complicated UTIs, offering patients more accessible and effective treatment options.