Background: This postmarketing surveillance assessed the real-world safety and effectiveness of selumetinib in pediatric patients with neurofibromatosis type 1 (NF1) and plexiform neurofibromas (PN) in Japan.
Methods: The surveillance was initiated on November 16, 2022, the launch date of selumetinib in pediatric indication in Japan. All patients treated with selumetinib were eligible for enrollment. The observation period was set to 3 years from drug initiation (data cutoff for 1-year analysis: October 9, 2024). Patient characteristics and safety and effectiveness data were captured using case report forms.
Results: In total, 52 patients were included in the analysis (median [range] age, 13.0 [5-20] years; age <19 years, 49 [94.2%] patients; female, 28 [53.8%] patients; dermatological, neurological, and bone manifestations [DNB] classification stage 5, 30 [57.7%] patients; median disease duration [N = 49], 118.0 months). The median treatment duration was 52.1 weeks, and 46 (88.5%) patients were on selumetinib treatment at 1 year. Adverse drug reactions (ADRs) and serious ADRs were observed in 46 (88.5%) and 9 (17.3%) patients, respectively. The most common ADRs were diarrhoea (28.8%), dermatitis acneiform (26.9%), blood creatine phosphokinase increased (23.1%), and paronychia (19.2%). No fatal ADRs were reported. The median time to the first onset of any ADR was 0.492 months. Investigator's assessment, target PN size on imaging, patient's general self-assessment, and performance status generally indicated the effectiveness of selumetinib.
Conclusions: The safety profile of selumetinib was generally consistent with the findings of the phase 2 SPRINT trial and Japanese phase 1 trial. No new safety concerns were identified.
Keywords: Japan; neurofibromatosis type 1; plexiform neurofibromas; postmarketing surveillance data; selumetinib.
© The Author(s) 2026. Published by Oxford University Press, the Society for Neuro-Oncology and the European Association of Neuro-Oncology.