On June 18, 2026, the FDA is expected to decide whether to approve tebipenem pivoxil hydrobromide (tebipenem HBr), an investigational oral carbapenem antibiotic developed by Spero Therapeutics and licensed to GSK, for the treatment of complicated urinary tract infections (cUTI), including pyelonephritis. If approved, tebipenem HBr would be the first oral carbapenem antibiotic available in the United States — a class that has been intravenous-only for decades.
The application is a Class 2 resubmission. The FDA issued a complete response letter (CRL) in June 2022 after the first NDA, requesting an additional phase 3 trial. GSK submitted the new data from the PIVOT-PO study in December 2025, and the FDA accepted the resubmission with a PDUFA date of June 18, 2026. Tebipenem HBr holds Qualified Infectious Disease Product (QIDP) and Fast Track designations.
For antimicrobial stewardship teams, hospital pharmacy committees, and payer organizations, the arrival of an oral carbapenem introduces new questions about formulary design, prior authorization criteria, site-of-care transitions, and stewardship guardrails. This article previews the evidence, the access landscape, and what stakeholders should be watching.
Short answer
| Parameter | Tebipenem HBr |
|---|---|
| Generic name | Tebipenem pivoxil hydrobromide |
| Drug class | Oral carbapenem antibiotic |
| Sponsor | Spero Therapeutics (licensed to GSK) |
| NDA type | Class 2 resubmission |
| PDUFA date | June 18, 2026 |
| Designations | QIDP, Fast Track |
| Proposed indication | cUTI including pyelonephritis |
| Pivotal trial | PIVOT-PO (phase 3) |
| Key advantage | First oral carbapenem; potential to avoid hospitalization or enable early discharge |
| Reference: ClinicalTrials.gov | NCT06059846 |
Why an oral carbapenem matters
Carbapenems — imipenem, meropenem, ertapenem, doripenem — are broad-spectrum beta-lactam antibiotics reserved for multidrug-resistant gram-negative infections. They are among the most important agents in the infectious disease armamentarium, but they have always required intravenous administration. That means patients with cUTI who need a carbapenem typically require hospitalization or outpatient IV therapy.
An effective oral carbapenem could:
- Avoid hospitalization for patients who would otherwise be admitted for IV carbapenem therapy
- Enable earlier discharge for hospitalized patients who could complete treatment at home
- Provide an oral step-down option from IV carbapenems, reducing the need for peripherally inserted central catheters (PICC lines) and home infusion services
- Address rising antimicrobial resistance, particularly extended-spectrum beta-lactamase (ESBL)-producing Enterobacterales, which are increasingly common in community-acquired urinary tract infections
The IDSA's 2025 guideline update on complicated UTI explicitly recommends transitioning from IV to oral antibiotics when patients are clinically improving and an effective oral option is available. An oral carbapenem would give clinicians a new tool to execute that recommendation in patients infected with resistant organisms.
PIVOT-PO: the pivotal phase 3 trial
The PIVOT-PO trial (NCT06059846) was a global, randomized, double-blind, active-controlled phase 3 study comparing oral tebipenem HBr to intravenous imipenem-cilastatin in hospitalized adults with cUTI, including pyelonephritis. The trial was stopped early for efficacy in May 2025 after an interim analysis demonstrated non-inferiority on the primary composite endpoint of clinical cure and microbiological eradication.
Key findings presented at IDWeek 2025:
- Primary endpoint met: Oral tebipenem HBr (600 mg every 6 hours) achieved an overall success rate of 58.5% (261/446 participants) compared to 60.2% (291/483 participants) for IV imipenem-cilastatin (500 mg every 6 hours). The adjusted treatment difference was −1.3% (95% CI: −7.5%, 4.8%), meeting the non-inferiority margin. The composite endpoint measured clinical cure plus microbiological eradication at the test-of-cure visit (approximately 17 days from first dose)
- Trial size: The global, double-blind trial enrolled 1,690 patients with cUTI, including acute pyelonephritis
- Resistant pathogens: Clinical and microbiological response rates in patients with infections caused by antimicrobial-resistant Enterobacterales, including ESBL-producing organisms, were consistent with the overall population
- Safety profile: Adverse events were consistent with the known carbapenem class profile. The most common adverse events (≥3% incidence) were diarrhea and headache, which were mild to moderate and non-serious
- Spectrum: Tebipenem HBr demonstrated activity against levofloxacin-resistant and ESBL-producing pathogens
The earlier phase 3 trial (ADAPT-PO), which formed the basis of the original 2022 NDA, had enrolled primarily Eastern European patients. The FDA's CRL highlighted concerns about the representativeness of the study population. GSK and Spero designed PIVOT-PO to address that deficiency, though the extent of US site enrollment has not been fully disclosed.
The first CRL and the path to resubmission
The original NDA for tebipenem HBr was submitted in 2021 based on the ADAPT-PO trial. In June 2022, the FDA issued a CRL. While the agency did not publicly disclose the specific deficiencies, analysts and the company's disclosures indicated that the FDA requested an additional phase 3 trial, likely driven by concerns about the adequacy of the data package — including the geographic composition of the study population.
Spero subsequently entered into an exclusive licensing agreement with GSK in September 2022, transferring IND and NDA sponsorship. GSK invested $66 million upfront and committed to fund the additional trial. The PIVOT-PO study was initiated and completed under Spero's execution with GSK's support. The positive results led to the December 2025 resubmission.
The QIDP designation provides an additional five years of marketing exclusivity upon approval, and the Fast Track designation enables rolling review and more frequent FDA interactions.
Access implications: what payers and formulary committees should watch
Formulary positioning
If approved, tebipenem HBr will likely be positioned as a specialty antibiotic with stewardship restrictions. Carbapenems are widely considered "last-resort" agents in antimicrobial stewardship programs, and an oral version will require careful formulary management to prevent overuse.
Expected formulary considerations:
- Prior authorization requiring documented resistant organism (e.g., ESBL-positive urine culture) or failure of first-line oral agents
- Infectious disease consultation requirements, similar to existing IV carbapenem stewardship protocols at many health systems
- Step therapy requiring trial of fluoroquinolones or other oral agents before tebipenem HBr, when susceptibility allows
- Restricted to cUTI/pyelonephritis indication — off-label use prevention will be a stewardship priority
Payer and benefit design
Tebipenem HBr is an oral medication, so it will be adjudicated under the pharmacy benefit — not the medical benefit where IV carbapenems currently sit. This has several implications:
- Pharmacy benefit managers (PBMs) will manage prior authorization rather than medical benefit UM teams
- Specialty pharmacy distribution is likely, given the expected cost and stewardship considerations
- Hospital discharge planning teams will need to coordinate pharmacy benefit prior authorization before discharge to avoid readmission
- Copay structure will differ from IV-infused alternatives, which are typically covered under the medical benefit with coinsurance
Site-of-care economics
An oral carbapenem could meaningfully reduce the cost of care for cUTI by:
- Shortening or avoiding hospital stays (average cUTI hospitalization: 4–7 days at $2,000–$4,000/day)
- Eliminating PICC line placement and home infusion nursing costs ($150–$300/day for home IV antibiotics)
- Reducing hospital-acquired infection risk associated with prolonged IV access
Health systems with capitated or bundled payment models may find oral carbapenem therapy economically favorable even at a premium drug cost.
Antimicrobial stewardship considerations
The infectious disease community has raised both enthusiasm and caution:
- Appropriate use: Stewardship programs should develop criteria for tebipenem HBr use, restricting it to patients with documented resistant organisms or clinical failure of narrower-spectrum agents
- Resistance risk: Broadening carbapenem access through an oral route could accelerate carbapenem-resistant Enterobacterales (CRE) if stewardship guardrails are weak
- Diagnostic stewardship: Payers may require culture and susceptibility data before approving tebipenem HBr, creating turnaround-time challenges in urgent clinical settings
- IDSA guideline alignment: The 2025 IDSA cUTI guideline update supports early IV-to-oral transition; tebipenem HBr would be a new tool for that pathway
Pricing outlook
GSK has not disclosed planned pricing for tebipenem HBr. Oral specialty antibiotics in the US typically launch in the $1,500–$4,000 per course range, though the specific price will depend on GSK's assessment of value versus IV carbapenem therapy, hospitalization costs avoided, and payer willingness to pay.
The QIDP designation provides additional exclusivity but does not constrain pricing. Payers will evaluate tebipenem HBr against the total cost of IV carbapenem therapy (drug + administration + hospital days) when assessing value.
What to watch
- June 18, 2026: PDUFA target action date for the tebipenem HBr NDA resubmission
- Labeling language: Whether the FDA restricts the indication to specific pathogen types or cUTI severity levels
- REMS or stewardship requirements: Whether the FDA imposes any risk evaluation or stewardship conditions on the approval
- GSK launch timing: How quickly GSK can execute commercial launch and secure payer coverage
- PBM formulary decisions: Watch for CVS Caremark, Express Scripts, and OptumRx positioning in their 2027 formulary updates
- Hospital formulary committee actions: Health systems will need to update antibiograms and stewardship protocols to incorporate an oral carbapenem
Sources
- Spero Therapeutics. "Spero Announces NDA Resubmission of Tebipenem HBr by GSK to the FDA for Complicated Urinary Tract Infections, Including Pyelonephritis." December 19, 2025. https://www.sperotherapeutics.com
- GSK. "Positive PIVOT-PO Phase III Data Show Tebipenem HBr's Potential as the First Oral Carbapenem Antibiotic for Patients with Complicated Urinary Tract Infections." October 21, 2025. https://www.gsk.com/en-gb/media/press-releases/positive-pivot-po-phase-iii-data-show-tebipenem-hbr-s-potential-as-the-first-oral-carbapenem-antibiotic-for-patients-with-complicated-urinary-tract-infections-cutis
- ClinicalTrials.gov. "A Study of Tebipenem HBr in Adults with Complicated Urinary Tract Infection." NCT06059846. https://clinicaltrials.gov/ct2/show/NCT06059846
- Spero Therapeutics Q1 2026 Form 10-Q, filed with the SEC. May 14, 2026. https://www.sec.gov
- Urology Times. "FDA Approval Sought for Tebipenem HBr for Complicated Urinary Tract Infections." https://www.urologytimes.com/view/fda-approval-sought-for-tebipenem-hbr-for-complicated-urinary-tract-infections
- Fierce Biotech. "GSK Unveils Pivotal Data on Oral Antibiotic Ahead of FDA Filing." October 21, 2025. https://www.fiercebiotech.com/biotech/gsk-unveils-pivotal-data-oral-antibiotic-ahead-fda-filing
- NCBI Bookshelf. "Complicated Urinary Tract Infections." StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK436013
