Background Plexiform neurofibromas (PNs) affect approximately 20% to 50% of patients with NF1 and can lead to pain, disfigurement, and compression of vital structures (Nguyen et al., 2011; Tchernev et al., 2016; Miller et al., 2019). Selumetinib, a MEK1/2 inhibitor, is the first and only pharmacological treatment licensed for the treatment of symptomatic, inoperable PNs in children with NF1 (approved by the US Food and Drug Administration in April 2020). The aim of this study was to assess the drivers for initiation of treatment as well as the impact of selumetinib treatment on the patient’s quality of life from the perspective of the patient’s caregiver. Methods This was a qualitative study of caregivers of children aged 2-17 years who were prescribed selumetinib for the treatment of their PN(s). Study materials were IRB reviewed and approved. Caregivers had to be a parent or primary caregiver of a patient who had been taking selumetinib for > 6 months. Telephone interviews were conducted with each caregiver and interview transcripts were developed from the audio recordings and thematic analysis of the data was performed to identify patterns. Demographic and clinical background information were summarized using descriptive statistics. Results The study included 12 caregivers who reported a mean patient age of 13.1 years (range 5 – 17 years) with an average duration of selumetinib treatment of 42.1 months (range 12 – 96 months.) Reported treatment goals mainly focused on tumor size reduction (n=5, 41.6%) and stabilization (n=4, 33.3%) of PN(s). Additional goals included a decrease in PN-associated pain (n=3, 25%). In terms of treatment response, a majority of caregivers (n=11, 91.6%) reported either stabilization or a reduction in size of PNs. While four caregivers (33.3%) reported no PN-associated pain pre-treatment, over half (n=7, 58.3%) reported that their child experienced a reduction in pain following selumetinib initiation. Of three caregivers who reported exhaustion as a pre-treatment symptom, all reported improvement in the child’s energy level. More than half (n=7, 58.3%) attributed psycho-social benefits, including social, emotional and learning, to selumetinib therapy. Conclusion Caregivers of NF1 PN pediatric patients are concerned about the presence of PNs and associated morbidities in their children. Treatment goals primarily focus on tumor shrinkage/stabilization and reduction in PN-associated pain. Most caregivers reported tumor stability and/or shrinkage, reduction in pain, as well as well improvement in psycho-social aspects following selumetinib therapy initiation in their children. References Miller DT, Freedenberg D, Schorry E, Ullrich NJ, Viskochil D, Korf BR; Council on Genetics and American College of Medical Genetics and Genomics. Health supervision for children with neurofibromatosis type 1. Pediatrics. 2019;143(5). Nguyen R, Kluwe L, Fuensterer C, Kentsch M, Friedrich RE, Mautner VF. Plexiform neurofibromas in children with neurofibromatosis type 1: frequency and associated clinical deficits. J Pediatr. 2011; 159(4):652-5.e2. Tchernev G, Chokoeva AA, Patterson JW, Bakardzhiev I, Wollina U, Tana C. Plexiform neurofibroma: a case report. Medicine (Baltimore). 2016 Feb;95(6):e2663.