Statistically significant failure to achieve key secondary endpoints. The current data do not demonstrate sufficient potential to achieve the planned scientific objectives. The need to optimize the allocation of company resources.

The purpose of this study is to evaluate the effectiveness, safety of selumetinib and patient's parameters of symptomatic inoperable PN NF1 in real clinical practice in Russia

This study will be non-interventional retrospective and prospective study. Assessment of parameters will be carried out as if a patient is treated in real-life clinical setting. The patients should be enrolled into this project after evaluation of eligibility criteria by an investigator 10 clinical sites. No additional procedures besides those already used in the routine clinical practice will be applied to the patients. Study population will consist of pediatric patients aged 3 years and older with NF1 and symptomatic inoperable PN who were prescribed with selumetinib

Inclusion Criteria:

• NF1 diagnosed (according to the criteria for evaluating NF1),
• Symptomatic inoperable PN,
• Patients receiving therapy with selumetinib. For newly treated patients - registration on the first day of starting treatment with selumetinib,
• Age at starting of selumetinib treatment ≥ 3 to ≤ 18 years old (included in the study or started the therapy at the age of 18 years old),
• Patients whose parents or guardians have signed a consent form.

Exclusion Criteria:

• Patients currently participating in an interventional study/clinical trial,
• Patients are excluded if there is evidence of an optic glioma, malignant glioma, malignant peripheral nerve sheath tumor, or other cancer, requiring treatment with chemotherapy or radiation therapy,
• Patients who receive other antitumor treatment options on optic nerve glioma, malignant glioma, malignant tumor of the peripheral nerve sheath, or other cancer. If the patient on selumetinib treatment develop optic nerve glioma, malignant glioma, malignant tumor of the peripheral nerve sheath, or other cancer, he can continue selumetinib therapy +\- other treatment options on physician decision,
• Female patients above 12 age who are pregnant /plan to become pregnant or at breast feeding.

Study population will consist of pediatric patients aged 3 years and older with NF1 and symptomatic inoperable PN who were prescribed with selumetinib