Utebzi (tebipenem pivoxil) approved in the US for adults with complicated urinary tract infections (cUTIs)

Rhea-AI Summary

Spero Therapeutics (Nasdaq: SPRO) and GSK (NYSE: GSK) received FDA approval for Utebzi (tebipenem pivoxil), the first and only oral carbapenem for adult complicated urinary tract infections (cUTIs), including pyelonephritis, caused by certain susceptible pathogens in patients with limited or no alternative oral options.

Approval is based on the phase III PIVOT-PO trial showing non-inferiority to intravenous imipenem-cilastatin, with a 58.5% overall success rate versus 60.2% for IV therapy. Utebzi is expected to be available in the US by the end of 2026.

Positive

• First and only oral carbapenem approved in US for adult cUTIs
• PIVOT-PO phase III trial met non-inferiority versus IV imipenem-cilastatin
• Large addressable cUTI population, over 3 million US cases annually
• Potential shift of some treatment from inpatient IV to outpatient oral care
• Confirms productive global licensing and development collaboration with GSK
• BARDA federal funding support reduces Spero’s historical development burden

Negative

• None.

News Market Reaction – SPRO

-23.83% 5.0x vol

13 alerts

-23.83% Session close to close

-34.0% Trough in 5 hr 23 min

$174.86M Market Cap

5.0x Rel. Volume

In the Jun 17 session, SPRO declined 23.83%, reflecting a significant negative market reaction. Argus tracked a trough of -34.0% from its starting point during tracking. Our momentum scanner triggered 13 alerts that day, indicating notable trading interest and price volatility. Trading volume was exceptionally heavy at 5.0x the daily average, suggesting significant selling pressure.

Data tracked by StockTitan Argus on the day of publication.

Market Context

The stock dropped -23.8% in the session following this news. A negative reaction despite positive ap...

Analysis

The stock dropped -23.8% in the session following this news. A negative reaction despite positive approval news fits a pattern where macro or sector pressures can overshadow company milestones. SPRO previously declined 1.69% after reporting a profitable 2025 despite strong fundamentals. With dependence on a single partnered asset and future commercialization and pricing unknowns, some holders may reassess risk even after this milestone, especially if biotech peers collectively traded lower on the same day.

Key Figures

Annual cUTI cases: 3 million cases Treatment failure rate: 34% cUTI healthcare costs: $6 billion per year +5 more

8 metrics

Annual cUTI cases 3 million cases cUTIs treated annually in the US

Treatment failure rate 34% cUTI treatment failure impacts up to this share of patients

cUTI healthcare costs $6 billion per year US healthcare costs attributable to cUTIs annually

Tebipenem success rate 58.5% overall success PIVOT-PO Phase III trial tebipenem arm (261/446)

Imipenem success rate 60.2% overall success PIVOT-PO trial imipenem-cilastatin IV arm (291/483)

Tebipenem arm size 446 participants Hospitalized cUTI patients receiving oral tebipenem pivoxil

Control arm size 483 participants Patients receiving intravenous imipenem-cilastatin

Tebipenem dose 600 mg oral Dose used for tebipenem pivoxil in PIVOT-PO trial

Historical Context

5 past events · Latest: May 28 (Neutral)

Pattern 5 events

Date	Event	Sentiment	24h Move	Catalyst
May 28	Board appointment	Neutral	-1.0%	Compass Pathways added an experienced biopharma executive to its board committees.
May 13	Q1 2026 earnings	Positive	+13.1%	Narrower net loss, lower expenses, and confirmation of tebipenem HBr PDUFA date.
May 05	Earnings date set	Neutral	+4.5%	Company scheduled Q1 2026 results and business update without a conference call.
Mar 26	FY 2025 earnings	Positive	-1.7%	Return to net income in 2025 and confirmation of tebipenem HBr PDUFA date.
Mar 18	Earnings date set	Neutral	+0.4%	Announcement of timing for Q4 and full-year 2025 financial results release.

24h Move is the share-price change in the day after each event; other market factors may also have contributed.

Pattern Detected

SPRO has generally reacted favorably to tebipenem- and earnings-related updates, with one notable divergence on strong full-year 2025 results.

Recent Company History

Over the last six months, Spero’s trajectory has centered on tebipenem HBr for cUTI, now reflected in the FDA approval of Utebzi. Earnings on March 26, 2026 highlighted a pivot to this single lead asset, positive 2025 net income, and a June 18, 2026 PDUFA date. Q1 2026 results on May 13 reiterated that timeline and cash runway into 2028, driving a 13.11% gain. Today’s approval advances this same program from regulatory review to an approved oral carbapenem option.

Key Terms

carbapenem, non-inferiority, multidrug-resistant, phase III, +4 more

8 terms

carbapenem medical

"First and only oral carbapenem antibiotic approved in the US"

Carbapenems are a class of powerful antibiotics used to treat severe or hard-to-treat bacterial infections, often reserved when other drugs no longer work. For investors, they matter because their clinical effectiveness, regulatory approvals, and the growing problem of bacterial resistance can strongly influence a drug’s market value, hospital demand, pricing power, and the commercial prospects of companies developing or selling new or improved versions.

non-inferiority medical

"PIVOT-PO trial demonstrating non-inferiority compared to intravenous treatment"

A non-inferiority trial is a type of clinical test designed to show a new treatment is not meaningfully worse than an existing standard by more than a pre-set, acceptable amount. Think of it like proving a new smartphone model has battery life close enough to the leading model while offering other advantages; for investors, a successful non-inferiority result can clear the way to regulatory approval and market uptake even when the new option isn’t superior in headline effectiveness.

multidrug-resistant medical

"Often caused by multidrug-resistant pathogens, these infections account for over $6 billion"

Multidrug-resistant describes a disease-causing organism — usually a bacterium, virus, or parasite — that no longer responds to several different medications used to treat it. For investors, this matters because it narrows treatment options, can raise costs and regulatory hurdles for new therapies, and increases demand and market value for effective drugs, diagnostics, or preventive measures, much like a stubborn weed that resists multiple herbicides and creates pressure for new solutions.

phase III medical

"PIVOT-PO phase III trial, which demonstrated non-inferiority of tebipenem pivoxil"

A Phase III trial is the late-stage clinical study that tests whether a medical treatment works and is safe in a large group of patients, often comparing it to standard care. Think of it as a final dress rehearsal or full-scale road test before regulators decide on approval; positive or negative results strongly influence a drug maker’s chance to sell the treatment, future revenue, and investment risk.

imipenem-cilastatin medical

"compared to intravenous imipenem-cilastatin in hospitalized patients with cUTI"

Imipenem-cilastatin is a combination drug used to treat serious bacterial infections: imipenem is a broad-spectrum antibiotic that kills bacteria, and cilastatin protects imipenem from being broken down by the kidneys so it stays effective. For investors, this matters because approvals, supply, pricing, and patterns of hospital use or antibiotic resistance can strongly influence sales and the value of companies that develop or market such drugs — think of cilastatin as a protective case that lets the antibiotic do its job.

microbiological eradication medical

"composite of clinical cure plus microbiological eradication at the test of cure visit"

The complete disappearance of a disease-causing germ from a patient or infected site, as shown by tests such as cultures or molecular assays. For investors this matters because it is a concrete measure of a treatment’s ability to clear an infection—like proof that a weed killer removed all roots—affecting regulatory approval chances, prescribing guidance, and the commercial value of a drug or diagnostic.

adverse events medical

"The most frequently reported adverse events (in ≥3% of patients) were diarrhoea"

Adverse events are any harmful or unwanted medical occurrences experienced by people using a drug, device, or undergoing a treatment, whether or not the problem is caused by the product. Think of them as complaints or breakdowns noticed during a trial or after a product is on the market; regulators record and investigate them. Investors care because clusters or serious adverse events can delay approvals, trigger costly studies or recalls, change labeling, and quickly alter a company’s revenue and risk profile.

pyelonephritis medical

"cUTIs including pyelonephritis, caused by certain susceptible pathogens"

A bacterial infection of the kidney that causes inflammation, pain, fever and sometimes serious complications such as scarring or sepsis; think of it as a blockage and infection in the body's plumbing that can require urgent antibiotic treatment or hospitalization. Investors watch pyelonephritis because it can drive demand for antibiotics and diagnostics, affect clinical trial safety and regulatory reviews, and create short- or long-term costs and liability risks for healthcare companies and insurers.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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• First and only oral carbapenem antibiotic approved in the US
• Approval based on PIVOT-PO trial demonstrating non-inferiority compared to intravenous treatmentⁱ
• More than 3 million cases of cUTIs are treated annually in the US with a third of patients impacted by resistant infections^ii,iii

CAMBRIDGE, Mass., June 17, 2026 (GLOBE NEWSWIRE) -- Spero Therapeutics, Inc. (Nasdaq: SPRO) and GSK plc (LSE/NYSE: GSK) today announced that the US Food and Drug Administration (FDA) has approved Utebzi, an oral antibiotic for the treatment of complicated urinary tract infections (cUTIs) including pyelonephritis¹, caused by certain susceptible pathogens² in adult patients who have limited or no alternative oral treatment options. This is the first and only oral carbapenem antibiotic approved for these patients. This approval is a result of GSK’s development and exclusive global licensing agreement (excluding select Asian territories) with Spero Therapeutics.^iv

There are more than 3 million cases of cUTI in the US annually and treatment failure impacts up to 34% of patients.^2,3 Often caused by multidrug-resistant pathogens,^v these infections account for over $6 billion per year in healthcare costs.³ Carbapenems are the standard treatment for severe or resistant infections, but until now have only been available through intravenous administration^vi, increasing hospital resource use and reducing patients’ quality of life.^vii Tebipenem pivoxil offers the potential for an effective oral alternative taken outside of a hospital setting.

Tony Wood, Chief Scientific Officer, GSK, said: “With antibiotic resistance continuing to rise, patients and healthcare professionals need new treatment options. The approval of Utebzi provides the first and only oral carbapenem antibiotic for appropriate adults with complicated UTIs, a solution that could help reduce reliance on hospital-based intravenous care and support efforts to address resistant infections.”

Dr. Bilal Chughtai, Chief of Urology at Plainview Hospital, Northwell Health and Associate Professor of Urology at the Zucker School of Medicine at Hofstra/Northwell, said: “For patients with complicated urinary tract infections (cUTIs) and their caregivers, this approval is a major milestone as today’s standard of care places a serious burden on them and hospitals. A new effective oral treatment offering an alternative option to intravenous care has the potential to enable more treatment in the outpatient settings with the ambition to improve their experience.”

Esther Rajavelu, President and Chief Executive Officer, Spero Therapeutics added: “The FDA approval of tebipenem pivoxil marks the culmination of more than a decade of dedication from our team, partners, and, most importantly, the patients who placed their trust in this program. We are proud to reach this important milestone. Through our partnership with GSK, we look forward to this much-needed oral treatment option reaching cUTI patients to help reduce the burden of the disease.”

This approval is supported by positive results from the PIVOT-PO phase III trial, which demonstrated non-inferiority of tebipenem pivoxil compared to intravenous imipenem-cilastatin in hospitalized patients with cUTI, including pyelonephritis, based on the overall response (composite of clinical cure plus microbiological eradication) at the test of cure visit. Tebipenem pivoxil (oral, 600 mg) achieved a 58.5% overall success rate (261/446 participants) compared to 60.2% overall success rate (291/483 participants) for imipenem-cilastatin (intravenous, 500 mg) (adjusted treatment difference: −1.3%; 95% CI: −7.5%, 4.8%). 

The safety profile of tebipenem pivoxil was generally similar to that of imipenem-cilastatin and other carbapenem antibiotics. The most frequently reported adverse events (in ≥3% of patients) were diarrhoea and headache; these events were all mild or moderate and non-serious.^viii

Tebipenem pivoxil is anticipated to be made available to US patients by the end of 2026. 

This approval confirms the successful and productive collaboration between GSK and Spero Therapeutics. The development of tebipenem pivoxil has been supported in part with federal funds from the US Department of Health and Human Services; Administration for Strategic Preparedness and Response; Biomedical Advanced Research and Development Authority (BARDA), under contract numbers HHSO100201800015C and HHSO100201300011C.

About tebipenem pivoxil

Tebipenem pivoxil was developed in collaboration with Spero Therapeutics^ix for the treatment of cUTIs, including pyelonephritis. In September 2022, GSK entered into an exclusive license agreement with Spero Therapeutics for the development and commercialization in all markets, except certain Asian territories. Under this agreement, GSK sub-licensed back to Spero Therapeutics the rights and responsibility to conduct certain development work, including the PIVOT-PO phase III study. The sponsorship of the New Drug Application has been transferred to GSK. As part of the license agreement, tebipenem pivoxil has received Qualified Infectious Disease Product and Fast Track designations from the US FDA. 

The US Prescribing Information will be available here [https://gskpro.com/content/dam/global/hcpportal/en_US/Prescribing_Information/Utebzi/pdf/UTEBZI-PI-PIL.PDF]

About the PIVOT-PO trial 

The PIVOT-PO trial was a global, randomized, double-blind, pivotal, non-inferiority (NI margin: -10%) phase III trial evaluating the potential of oral tebipenem pivoxil compared to IV imipenem-cilastatin, in hospitalized adult patients with complicated urinary tract infections, including acute pyelonephritis. Patients were randomized 1:1 to receive tebipenem pivoxil (600 mg) orally every six hours, or imipenem-cilastatin (500 mg) IV every six hours, for a total of seven to ten days. Dose adjustments were made for patients with reduced renal function. Matching placebos were used to maintain blinding. The primary efficacy endpoint was composite response (combined per-patient clinical cure and microbiological response) at the test-of-cure visit (about 17 days from first dose administration of study drug) in patients with qualifying pathogens susceptible to imipenem. The trial enrolled a total of 1,690 patients, with randomization stratified by age, baseline diagnosis (cUTI or acute pyelonephritis), and the presence or absence of urinary tract instrumentation. For further details on the trial, refer to clinicaltrials.gov identifier NCT06059846.^x

About complicated urinary tract infections (cUTIs)

cUTIs are broadly described as any UTI that carries an increased risk of morbidity and mortality.⁵ Definitions of cUTIs are not currently uniform among international societies and regulatory agencies. cUTIs encompass a heterogeneous patient population due to the wide range of host factors, comorbidities and urological abnormalities associated with cUTIs. Risk factors for cUTIs include indwelling catheters, ureteric stents, neurogenic bladder, obstructive uropathy, urinary retention, urinary diversion, kidney stones, diabetes mellitus, immune deficiency, urinary tract modification and UTIs in renal transplant patients.^{xi,xii,xiii,xiv}

About GSK
GSK is a global biopharma company with a purpose to unite science, technology and talent to get ahead of disease together. Find out more at gsk.com.

About Spero Therapeutics
Spero Therapeutics, headquartered in Cambridge, Massachusetts, is a clinical-stage biopharmaceutical company focused on identifying and developing novel treatments for rare diseases and diseases with high unmet need. For more information, visit www.sperotherapeutics.com.

Forward Looking Statements

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended, including, without limitation, statements regarding the potential Utebzi to meaningfully improve treatment options for cUTI patients; the potential of Utebzi to help reduce reliance on hospital-based intravenous care and support efforts to address resistant infections; the potential of Utebzi to enable more treatment options in outpatient settings with the ambition to improve patients’ experience; the potential of tebipenem HBr to set a new standard of care and decrease the disease burden. In some cases, forward-looking statements may be identified by terms such as “may,” “will,” “should,” “expect,” “plan,” “aim,” “anticipate,” “could,” “intent,” “target,” “project,” “contemplate,” “believe,” “estimate,” “predict,” “potential” or “continue,” the negative of these terms or other similar expressions. Any forward-looking statements in this press release are based on management’s current expectations and beliefs and are subject to a number of important risks, uncertainties and other factors that may cause actual results to differ materially from those indicated by such forward looking statements, including, but not limited to, whether Spero and GSK will successfully perform their respective obligations under the collaboration between Spero and GSK; risks and uncertainties related to the successful commercial launch of Utebzi and market acceptance; the competitive landscape for Utebzi, risks related to Spero’s expectations regarding the potential clinical benefit of Utebzi to patients; the risk that any regulatory approval may be subject to significant limitations on use or subject to withdrawal or other adverse actions by the applicable regulatory authority; the uncertainties inherent in research and development, including clinical results; regulatory actions or delays or government regulation generally; Spero’s ability to protect its intellectual property portfolio; Spero’s reliance on third parties to manufacture, develop, and commercialize its product candidates; Spero’s reliance on GSK, pursuant to the exclusive GSK License Agreement, to advance development of tebipenem pivoxil and GSK’s right thereunder to determine, in its sole discretion, whether to further develop and commercialize tebipenem pivoxil; Spero’s need for additional funding; Spero’s ability to retain key personnel; whether Spero’s cash resources will be sufficient to fund its continuing operations for the periods anticipated; and other factors discussed in the “Risk Factors” set forth in filings that Spero periodically makes with the SEC. The forward-looking statements included in this press release represent Spero’s views only as of the date hereof and should not be relied upon as representing its views as of any subsequent date. Except as required by law, Spero explicitly disclaims any obligation to update any forward-looking statements.

Investor Relations Contact:
Shai Biran, PhD
Spero Therapeutics
IR@Sperotherapeutics.com

Media Inquiries:
media@sperotherapeutics.com

¹ Pyelonephritis is a specific type of UTI that has travelled up the urinary tract to infect one or both kidneys.

² Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae species complex, Klebsiella oxytoca, and Enterococcus faecalis. 

ⁱ GSK press release, “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)”, October 2025. Available at: press-release-tebi-pivot-po-phase-iii-read-out.pdf (last accessed: May 2026)

ⁱⁱ Carreno JJ, et al. “Longitudinal, nationwide, cohort study to assess incidence, outcomes, and costs associated with complicated urinary tract infection” in Open Forum Infect Dis. 2019;7:ofil446. doi: 10.1093/ofid/ofz446

ⁱⁱⁱ Lodise TP, et al. Hospital admission patterns of adult patients with complicated urinary tract infections who present to the hospital by disease acuity and comorbid conditions: How many admissions are potentially avoidable? Am J Infect Control. 2021;49(12):1528-1534.

^iv GSK press release, GSK and Spero Therapeutics announce exclusive licence agreement for tebipenem HBr, a late-stage antibiotic that may treat complicated urinary tract infections, 22 September 2022

^v Sabih A, Leslie SW. “Complicated urinary tract infections” in StatPearls. 2023. StatPearls Publishing: Treasure Island, FL, USA.

^vi Eckburg PB, et al. “Oral tebipenem pivoxil hydrobromide in complicated urinary tract infection”. In New England Journal of Medicine,. 2022;386:1327-1338. doi: 10.1056/NEJMoa2105462

^vii NHS. Reducing complications with a prolonged hospital stay. 2024. Available from: https://www.plymouthhospitals.nhs.uk/display-pil/pil-reducing-complications-with-a-prolonged-hospital-stay-6686 (last accessed: May 2026)

^viii GSK press release, 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), October 2025

^ix GSK press release, GSK and Spero Therapeutics announce exclusive licence agreement for tebipenem HBr, a late-stage antibiotic that may treat complicated urinary tract infections, 22 September 2022

^x CT.gov, A Study of Oral Tebipenem Pivoxil Hydrobromide (TBP-PI-HBr) Compared to Intravenous Imipenem-cilastatin in Participants With Complicated Urinary Tract Infection (cUTI) or Acute Pyelonephritis (AP) (PIVOT-PO), last updated on 01 July 2025

^xi Bonkat G, et al. “Keep it Simple: A Proposal for a New Definition of Uncomplicated and Complicated Urinary Tract Infections from the EAU Urological Infections Guidelines Panel”. Eur Urol. 2024;86(3):195-197.

^xii Wagenlehner FME, et al. Epidemiology, definition and treatment of complicated urinary tract infections. Nat Rev Urol. 2020;17(10):586-600.

^xiii Gomila A, et al. Predictive factors for multidrug-resistant gram-negative bacteria among hospitalized patients with complicated urinary tract infections. Antimicrob Resist Infect Control. 2018;7:111.

^xiv Altunal N, et al. Ureteral stent infections: a prospective study. Braz J Infect Dis. 2017;21(3):361-364.

FAQ

What did the FDA approve for Spero Therapeutics (SPRO) on June 17, 2026?

The FDA approved Utebzi (tebipenem pivoxil) for adults with complicated urinary tract infections, including pyelonephritis. According to Spero Therapeutics and GSK, it is the first and only oral carbapenem antibiotic approved for these cUTI patients in the US.

What is Utebzi (tebipenem pivoxil) and which infections does it treat?

Utebzi is an oral carbapenem antibiotic for adult complicated urinary tract infections, including pyelonephritis. According to Spero Therapeutics, it targets infections caused by certain susceptible pathogens in patients who have limited or no alternative oral treatment options.

How did Utebzi perform in the PIVOT-PO phase III trial versus IV therapy?

In the PIVOT-PO trial, oral tebipenem pivoxil showed non-inferiority to IV imipenem-cilastatin. According to GSK, Utebzi achieved a 58.5% overall success rate versus 60.2% for IV therapy, based on a composite of clinical cure and microbiological eradication.

When will Utebzi be available in the United States for cUTI patients?

Utebzi is anticipated to be available to US patients by the end of 2026. According to Spero Therapeutics and GSK, the oral option may allow some complicated urinary tract infections to be managed outside hospital settings, where appropriate.

What is the safety profile of Utebzi (tebipenem pivoxil) for adults with cUTIs?

Utebzi’s safety profile was generally similar to imipenem-cilastatin and other carbapenems in trials. According to GSK, the most frequent adverse events (≥3% of patients) were mild to moderate, non-serious diarrhoea and headache.

How large is the US complicated urinary tract infection market targeted by Utebzi?

More than 3 million cUTI cases are treated annually in the US. According to Spero Therapeutics and GSK, up to 34% of patients experience treatment failure, and these infections account for over $6 billion in yearly healthcare costs.

What role did BARDA funding and the GSK partnership play in Utebzi’s development?

Development of tebipenem pivoxil was supported by BARDA federal funds and a global licensing deal with GSK. According to Spero Therapeutics, this collaboration enabled successful development and regulatory approval, excluding select Asian territories from the license.