Low-dose Selumetinib for the Treatment of Plexiform Neurofibromas in Chinese Children

Neurofibromatosis type 1 (NF1) is an autosomal dominant genetic disorder that affects multiple organ systems, with an estimated prevalence of approximately 1/3000. Around 50% of NF1 develop plexiform neurofibromas (PN), which can exhibit invasive growth, leading to compression of surrounding tissues. PN can progress rapidly within a short period, resulting in severe deformities and functional impairments that significantly impact the patient's quality of life. In 2020, selumetinib was approved in the United States for the treatment of symptomatic PN patients aged ≥2 years who were ineligible for surgery, bringing new breakthroughs to this large patient population in China. In recent years, clinical trials have been conducted in many countries and regions to evaluate the efficacy and safety of selumetinib in the treatment of PN. Studies have demonstrated that after one year of treatment, 70% of patients achieved confirmed partial lesion reduction, accompanied by significant improvements in pain symptoms and quality of life. Furthermore, the safety was favorable, with 97.7% of adverse reactions classified as Grade I or II. In China, a single-arm clinical trial involving 16 children also showed that all patients had controlled lesions, of which 63% of children had confirmed partial relief. However, the current dosage for children in China refers to the recommended value of Phase I clinical trials (25 mg/m²) in the United States. There remains a lack of pharmacokinetic and pharmacodynamic data specific to the Chinese population. Since racial differences can influence drug metabolism, the current dosage may exceed the tolerance level for some Chinese children, potentially increasing the risk of serious adverse reactions. Clinically, families frequently report a high incidence of adverse effects such as paronychia, abdominal pain, and rash. Therefore, conducting a dose optimization study based on the Chinese population and exploring the efficacy and safety of low-dose selumetinib in the treatment of PN in Chinese children is of great significance. These efforts will guide clinical practice, reduce adverse reactions, and enhance treatment outcomes.