RARE-02. OBSERVATIONAL REGISTRY STUDY OF TREATMENT PRACTICES AND LONG-TERM OUTCOMES OF CHILDREN WITH NEUROFIBROMATOSIS TYPE 1 (NF1) AND PLEXIFORM NEUROFIBROMAS (PN) INITIATING SELUMETINIB IN REAL-WORLD PRACTICE IN THE UNITED STATES (US): STUDY DESIGN AND METHODOLOGY

Selumetinib (ARRY-142886, AZD6244) is an oral, allosteric MEK1/2 inhibitor approved in the US for children aged ≥2 years with NF1 and symptomatic, inoperable PN, based on results from the pivotal SPRINT study. Aims of the US Selumetinib Registry study [NCT05683678] include understanding treatment practices and assessing short- and long-term safety and effectiveness outcomes of selumetinib treatment in children with NF1-PN in real-world US practice. Clinical and non-clinical factors affecting outcomes will also be explored. This observational registry study of pediatric patients with NF1-PN will be conducted in up to 22 US centers. Eligible patients will be 2–18 years old at the time of selumetinib initiation (on/after April 10, 2020), and not currently participating in a clinical trial. Patients will be divided into three cohorts: Cohort 1 – treatment discontinued before enrollment, Cohort 2 – treatment initiated before enrollment and currently on treatment, Cohort 3 – treatment initiation intended within 3 months of enrollment. Patients will be followed for ≥36 and up to 60 months. Primary objectives are to describe patient demographics and disease characteristics (including diagnosis criteria and related manifestations, diagnostic tests and results, and PN-related morbidities), selumetinib treatment course, short- and long-term effectiveness and safety, and disease course and treatment following discontinuation. Key secondary objectives include measures of quality of life, pain and physical functioning before, during, and after selumetinib. Target enrollment is 200 patients with a 24-month enrollment period and will begin in 2023. The US Registry study will facilitate understanding of treatment practices and assess short and long-term outcomes of selumetinib for NF1-PN in a real-world setting.