This week, the FDA granted the antifungal, isavuconazonium sulfate (Cresmba, Astellas Pharma), both an orphan drug designation and pediatric exclusivity status. Late last year, the therapy was FDA approved for the treatment of invasive aspergillosis (IA) and invasive mucormycosis (IM) in pediatric patients as young as 1 years old, making it the only azole antifungal approved for this age group.

This orphan drug designation means that Astellas has received a marketing rights exclusivity for 7 years in those indications beginning from the date of approval of the supplemental New Drug Application on December 8, 2023. Pediatric exclusivity extends that period by another 6 months.¹ These federal actions help to ensure the therapy has market viability.

"Astellas recognizes the importance of addressing significant unmet medical needs, especially for pediatric patients with rare and potentially life-threatening IA and IM infections,” Laura Kovanda, PhD, executive director, asset lead, BioPharma Development, Astellas, said in a statement. “I am incredibly proud of the Astellas team for advancing research, development and commercialization to offer Cresemba to pediatric patients who have limited treatment options."¹

FDA Approval and What the Data Showed
At the time of the approval last December, the therapy was indicated for the youngest patients. And for pediatric patients with compromised immune systems, they are at a higher risk for IA and IM. "Invasive fungal infections are a significant concern to healthcare professionals who care for pediatric, adolescents and young adults with hematologic malignancies, transplant recipients and primary immune deficiencies," said Antonio Arrieta, MD, medical director, Pediatric Infectious Disease, Children's Health of Orange County. "IA, currently the most common invasive mold infection in these patients, and IM are associated with significant morbidity and high fatality rates. The FDA approval of Cresemba for pediatric patients adds a much-needed treatment option."²

In the youngest patient population, isavuconazonium sulfate is recommended as an injection. In addition, isavuconazonium sulfate capsules are approved for pediatric patients 6 years of age and older who weigh 35 pounds and greater. The capsules had already been approved for adults.²

Isavuconazonium sulfate is manufactured by Astellas, and back in 2010, Basilea Pharmaceutica partnered with Astellas to complete phase 3 trials, obtain regulatory approvals, and market the drug. In 2013 and 2014, the partners won orphan drug designation in the US for isavuconazonium for treating invasive aspergillosis, mucormycosis, and invasive candidiasis in adults.²

Isavuconazonium is an azole antifungal, and the approval is based off the results of 2 clinical trials, including a phase 2 open-label, non-comparative, multicenter study evaluating the safety, efficacy and pharmacokinetics of isavuconazonium sulfate for the treatment of IA or IM in pediatric patients aged 1 to 17 years old. In the study, 31 patients aged 1 to 17 with possible, probable or proven IA or IM were treated with isavuconazonium sulfate (10 mg/kg) every 8 hours on days 1 and 2, and once-daily thereafter for ≤84 days for IA or ≤180 days for IM.²

Median treatment duration was 55 days. All-cause case fatality through Day 42 was 6.5% and through day 84 was 9.7% which occurred during the follow-up period and none were considered treatment-related. Successful response rates were 54.8% at the end of treatment. Treatment emergent adverse events (TEAEs) occurred in 93.5% of patients and 29.0% patients experienced drug-related TEAEs. Treatment was withdrawn in two patients due to TEAEs. Serious TEAEs occurred in 58.1% of patients and were assessed as drug-related by the investigator in 1 patient.²

References

1. FDA Grants Orphan Drug and Pediatric Exclusivities for CRESEMBA® (isavuconazonium sulfate) for Invasive Aspergillosis and Invasive Mucormycosis in Children. Astellas Pharma press statement. March 11, 2024. Accessed March 14, 2024.
https://newsroom.astellas.us/2024-03-11-FDA-Grants-Orphan-Drug-and-Pediatric-Exclusivities-for-CRESEMBA-R-isavuconazonium-sulfate-for-Invasive-Aspergillosis-and-Invasive-Mucormycosis-in-Children

2. Parkinson J. FDA Approves Therapy for Fungal Infections in Young Children. Contagionlive.com. December 9, 2023. Accessed March 14, 2024.
https://www.contagionlive.com/view/fda-approves-therapy-for-fungal-infections-in-young-children