Basilea receives further USD 6 million from BARDA to continue development of novel antibiotic ceftibuten-ledaborbactam

Ad hoc announcement pursuant to Art. 53 LR

Allschwil, Switzerland, February 25, 2026

Basilea Pharmaceutica Ltd, Allschwil (SIX: BSLN), a commercial-stage biopharmaceutical company committed to meeting the needs of patients with severe bacterial and fungal infections, announced today that the Biomedical Advanced Research and Development Authority (BARDA), part of the Administration for Strategic Preparedness and Response (ASPR) within the U.S. Department of Health and Human Services, awarded USD 6 million to Basilea to continue the development of Basilea’s novel oral antibiotic ceftibuten-ledaborbactam etzadroxil, a beta-lactam/beta-lactamase inhibitor (BL/BLI) combination, for the treatment of complicated urinary tract infections (cUTIs), including pyelonephritis.

David Veitch, Chief Executive Officer of Basilea, said: “We are very pleased to receive the continued funding from BARDA to support the further development of our novel antibiotic ceftibuten-ledaborbactam, including the preparation of clinical phase 3 studies. We believe that, by addressing the critical unmet medical need for the oral treatment of cUTIs caused by multidrug-resistant bacteria, this candidate holds a strong promise for patients suffering from these severe infections.”

Under the terms of the specific Contract^[1] with BARDA, upon completion of predefined milestones, Basilea could be reimbursed for a significant proportion of the further development costs required to bring the candidate to market, including the planned phase 3 clinical studies. After the current tranche of USD 6 million, the Contract could provide up to USD 147 million of additional non-dilutive funding.

About beta-lactam/beta-lactamase inhibitor (BL/BLI) combinations

Many Gram-negative bacteria express enzymes such as extended spectrum beta-lactamases (ESBL) that confer resistance against commonly used antibiotics. Beta-lactamase inhibitors block these enzymes and restore the activity of beta-lactam antibiotics against initially resistant Gram-negative bacteria, therefore BL/BLI combinations are an important addition to the armamentarium for the treatment of infections caused by multidrug-resistant bacterial pathogens.

About ceftibuten-ledaborbactam etzadroxil

Ledaborbactam etzadroxil is the orally bioavailable prodrug of ledaborbactam, a novel broad-spectrum boronic acid beta-lactamase inhibitor, which is being developed in combination with ceftibuten, an oral cephalosporin antibiotic, which is approved in the US for the treatment of upper and lower respiratory tract infections and for urinary tract infections outside the US. In vitro and in vivo studies demonstrated that ledaborbactam etzadroxil restores the activity of ceftibuten against strains of Enterobacterales expressing Ambler class A extended spectrum beta-lactamases (ESBLs), class C cephalosporinases, and class A and D carbapenemases (KPC and OXA-48, respectively) as well as multidrug-resistant (MDR) Enterobacterales.^[2] Ceftibuten-ledaborbactam etzadroxil has been granted Qualified Infectious Disease Product (QIDP) and Fast Track designations by the US Food and Drug Administration (FDA) for cUTI and uncomplicated urinary tract infections. Ceftibuten-ledaborbactam etzadroxil is an investigational drug and is not yet approved in any country for commercial use.

About complicated urinary tract infections (cUTI)

Complicated UTIs, which include pyelonephritis (kidney infections), are defined as urinary tract infections ascending from the bladder accompanied by local and systemic signs and symptoms and are one of the most common bacterial infections in hospital and community settings. Increasing resistance of bacteria causing complicated urinary tract infections has led to limited availability of effective oral antibiotic treatment options.^[3] Currently, there are no approved oral beta-lactam or beta-lactam/beta-lactamase inhibitor combinations that are effective against Enterobacterales expressing Ambler class A ESBLs, class C cephalosporinases, and class A & D serine carbapenemases (KPC and OXA-48).

About Basilea

Basilea is a commercial-stage biopharmaceutical company founded in 2000 and headquartered in Switzerland. We are committed to discovering, developing and commercializing innovative drugs to meet the needs of patients with severe bacterial and fungal infections. We have successfully launched two hospital brands, Cresemba for the treatment of invasive fungal infections and Zevtera for the treatment of bacterial infections. In addition, we have preclinical and clinical anti-infective assets in our portfolio. Basilea is listed on the SIX Swiss Exchange (SIX: BSLN). Please visit basilea.com.

Disclaimer

This communication expressly or implicitly contains certain forward-looking statements, such as "believe", "assume", "expect", "forecast", "project", "may", "could", "might", "will" or similar expressions concerning Basilea Pharmaceutica Ltd, Allschwil and its business, including with respect to the progress, timing and completion of research, development and clinical studies for product candidates. Such statements involve certain known and unknown risks, uncertainties and other factors, which could cause the actual results, financial condition, performance or achievements of Basilea Pharmaceutica Ltd, Allschwil to be materially different from any future results, performance or achievements expressed or implied by such forward-looking statements. Basilea Pharmaceutica Ltd, Allschwil is providing this communication as of this date and does not undertake to update any forward-looking statements contained herein as a result of new information, future events or otherwise.

For further information, please contact:

Peer Nils Schröder, PhD Head of Corporate Communications & Investor Relations Basilea Pharmaceutica International Ltd, Allschwil Hegenheimermattweg 167b 4123 Allschwil Switzerland
Phone	+41 61 606 1102
E-mail	media_relations@basilea.com investor_relations@basilea.com

This ad hoc announcement can be downloaded from www.basilea.com.

References

1. This project has been funded in part with federal funds from the U.S. Department of Health and Human Services; Administration for Strategic Preparedness and Response; Biomedical Advanced Research and Development Authority, under Contract No. 75A50123C00050.
2. J. A. Karlowsky, M. G. Wise, M. A. Hackel et al. Ceftibuten-Ledaborbactam Activity against Multidrug-Resistant and Extended-Spectrum-β-Lactamase-Positive Clinical Isolates of Enterobacterales from a 2018–2020 Global Surveillance Collection. Antimicrobial Agents and Chemotherapy 2022, Nov 15;66(11):e0093422
3. T. P. Lodise, T. Chopra, B. H. Nathanson et al. Epidemiology of Complicated Urinary Tract Infections due to Enterobacterales Among Adult Patients Presenting in Emergency Departments Across the United States. Open Forum Infectious Diseases 2022, Jun 24;9(7):ofac315.
   

Attachment

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