Alexion, AstraZeneca Rare Disease Koselugo gets USFDA nod for neurofibromatosis type 1

The approval by the US Food and Drug Administration (FDA) was based on positive results from KOMET, the largest and only placebo-controlled global Phase III trial in this patient population. Data were presented at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting and published in The Lancet.

NF1 is a rare, progressive, genetic condition usually diagnosed in early childhood, but often progressing into adulthood, that can impact every organ system. Up to 50% of people living with NF1 may develop a type of non-malignant tumour called PN that may affect the brain, spinal cord and nerves. PN may appear later in a person’s life and can grow and become large, leading to pain, disfigurement and muscle weakness, among other debilitating symptoms.

Prof. Pierre Wolkenstein, MD, PhD, Head of the Department of Dermatology at Henri Mondor Hospital, APHP, Paris East University (UPEC), and Investigator of the KOMET trial, said, “The KOMET Phase III trial, which builds on the established clinical profile of Koselugo and its real-world use in paediatric patients, underscores its potential to address the substantial and oftentimes progressive clinical burdens associated with PN in adulthood. This approval reaffirms the role of Koselugo as a strong option for the treatment of adult and paediatric patients with NF1 PN.”

Marc Dunoyer, Chief Executive Officer, Alexion, said, “This expanded approval of Koselugo in adults with NF1 PN, together with the recently approved granule formulation for young children aged one year and older, enables much-needed continuity of care and supports patients across the disease journey in the US. As the first approved therapy in NF1 PN, backed by more than a decade of clinical evidence, Koselugo has transformed the treatment standard for this rare disease.”

Annette Bakker, PhD, Chief Executive Officer, Children’s Tumor Foundation, said, “We celebrate this FDA approval of Koselugo for adults with NF1 plexiform neurofibromas—a major step forward for NF patients everywhere. Koselugo has already changed what is possible for children with NF1, and now adults will benefit from that same progress. It is proof that NF research is delivering real results and opening the door to even more treatment options. This milestone shows what can be achieved when scientists, clinicians, industry and the NF community work together with one focus: getting effective treatments to patients faster.”

In the primary analysis of the KOMET Phase III trial, Koselugo showed a statistically significant and clinically meaningful overall response rate (ORR) of 20% (n=14/71, 95% confidence interval [CI]: 11, 31) compared to 5% with placebo (n=4/74, 95% CI: 2, 13; p=0.011) by cycle 16, with 86% of patients on Koselugo having an observed duration of response (DOR) of at least 6 months. After 12 cycles, patients on placebo were switched to Koselugo and patients on Koselugo remained on treatment for an additional 12 cycles.

The safety of Koselugo in the KOMET Phase III trial was consistent with its known profile and established use in paediatric patients.

Koselugo has been recently approved in the EU, Japan and other countries for the treatment of adult patients with NF1 who have symptomatic, inoperable PN based on data from the KOMET Phase III trial, and additional regulatory reviews are ongoing. In the US, Koselugo granules have recently been approved for paediatric patients one year of age and older with NF1 PN.