Basilea announces start of clinical study by partner Asahi Kasei Therapeutics in Japan with antifungal Cresemba® (isavuconazole) in pediatric patients

Allschwil, Switzerland, September 14, 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 its partner Asahi Kasei Therapeutics Corp. started a phase 2 clinical study in Japan with the antifungal Cresemba^® (isavuconazole) for pediatric patients at risk of deep mycoses.

Dr. Marc Engelhardt, Chief Medical Officer of Basilea, said: “We are very pleased with the start of the pediatric study for Cresemba by our partner Asahi Kasei Therapeutics Corp. Invasive fungal infections pose a critical threat for children suffering from hematologic malignancies or immunodeficiency disorders. Despite this high-risk setting, treatment options remain limited. Making Cresemba available to pediatric patients in Japan would represent a major advance in addressing this important medical need.”

The multicenter, open-label, non-controlled study is assessing the safety and pharmacokinetics of Cresemba in children at risk from deep mycoses.

Cresemba is already approved for the treatment of children in the US, Canada, Europe and China. In Japan, Cresemba is approved for the treatment of adults with severe fungal infections, but currently not for use in pediatric patients.

About Cresemba^® (isavuconazole)

Cresemba, with the active ingredient isavuconazole, is an intravenous (i.v.) and oral azole antifungal. Cresemba is marketed in more than 70 countries. In Japan, orally and intravenously administered isavuconazole is approved for use in adults for the treatment of aspergillosis (invasive aspergillosis, chronic progressive pulmonary aspergillosis, simple pulmonary aspergilloma), mucormycosis, and cryptococcosis (pulmonary cryptococcosis and disseminated cryptococcosis). Isavuconazole is also approved in the European Union¹, the United Kingdom², the United States (US)³ and many additional countries, including in the Asia Pacific region.⁴

According to the latest available market data, total global in-market sales of Cresemba in the twelve-month period between April 2025 and March 2026 amounted to USD 782 million, a 27 percent growth year-on-year, making it the largest branded antifungal for invasive fungal infections worldwide.⁵

Deep mycoses

Deep mycoses like invasive aspergillosis (IA), invasive mucormycosis (IM) and invasive cryptococcosis are life-threatening fungal infections that spread beyond superficial sites into deep tissues, including lung, eyes, brain, bones, the bloodstream, and other sites or organs. They predominantly affect immunocompromised patients, including patients with hematologic malignancies (blood cancer), transplant patients, or patients with immunodeficiency disorders. These infections are associated with high morbidity and mortality, also in pediatric patients.^{6, 7, 8}

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.

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This press release can be downloaded from www.basilea.com.

References

1. European Public Assessment Report (EPAR) Cresemba: https://www.ema.europa.eu/en/medicines/human/EPAR/cresemba [Accessed: September 13, 2026]
2. Summary of Product Characteristics (SmPC) Cresemba: https://www.medicines.org.uk/emc/search?q=cresemba [Accessed: September 13, 2026]
3. Full US prescribing information: https://www.astellas.us/docs/cresemba.pdf [Accessed: September 13, 2026]
4. The registration status and approved indications may vary from country to country.
5. IQVIA Analytics Link, March 2026. In-market sales reported as moving annual total (MAT) in US dollar.
6. J. Cadena, G. R. Thompson 3rd, T. F. Patterson. Aspergillosis: Epidemiology, Diagnosis, and Treatment. Infectious Disease Clinics of North America 2021 (35), 415-434
7. M. Slavin, S. van Hal, T. C. Sorrell et al. Invasive infections due to filamentous fungi other than Aspergillus: epidemiology and determinants of mortality. Clinical Microbiology and Infection 2015 (21), 490.e1-490.e10
8. Z. D. Pana E. Roilides, A. Warris et al. Epidemiology of Invasive Fungal Disease in Children. Journal of the Pediatric Infectious Diseases Society 2017 (6), suppl. 1, S3-S11

Attachment

• Basilea Press release