US regulators have issued a green light for AstraZeneca and MSD's kinase inhibitor Koselugo (selumetinib) for patients with the rare and debilitating genetic disorder neurofibromatosis.

The decision, which marks approval of the first treatment for the condition anywhere in the world, allows use of the drug in paediatric patients two years of age and older with neurofibromatosis type 1 (NF1) who have symptomatic, inoperable plexiform neurofibromas (PN).

NF1 is a rare and debilitating genetic condition. Some 30-50% of patients with NF1 experience PN – tumours growing inside their nerve sheaths. These PN can cause clinical issues such as pain, motor dysfunction, airway dysfunction, bowel/bladder dysfunction and disfigurement.

The approval came on the back of clinical data showing a 66% overall response rate – the percentage of patients with confirmed complete or partial response of at least 20% reduction in tumour volume – in paediatric patients with NF1 PN when treated with Koselugo as a twice-daily oral monotherapy.

“For the first time, patients and families impacted by this incurable genetic condition have an approved medicine to treat the resulting plexiform neurofibromas,” noted Dave Fredrickson, executive vice president, Oncology Business Unit.