OBJECTIVES: Selumetinib, an oral MEK1/2 inhibitor, received U.S. Food and Drug Administration approval in April 2020 for pediatric patients (aged ≥2 years) with neurofibromatosis type 1 (NF1) and symptomatic, inoperable plexiform neurofibromas (PN). PN may develop anywhere in the body, can cause pain, and may impair quality of life. This study aimed to evaluate real-world changes in pain medication utilization (PMU) post-selumetinib initiation.

METHODS: This descriptive, non-interventional, retrospective cohort study used Merative™ MarketScan® Research Databases to identify patients aged 2–18 years with continuous enrollment 6 months before and after first selumetinib prescription (index), and ≥2 selumetinib prescription fills (4/10/2020–12/31/2022). PMU was assessed. A paired generalized estimating equation (GEE) model with exchangeable correlation structure estimated difference in PMU (≥1 prescription fill of pain medication) pre- and post-selumetinib initiation. GEE was adjusted for sex, age, and Charlson Comorbidity Index.

RESULTS: Of 90 eligible patients, the mean (standard deviation) age at index was 12.0 (4.3) years, 65.6% (n=59) had NF1 and PN diagnoses, 65.6% (n=59) were male, and 67.8% (n=61) had commercial insurance. General baseline indicators of pain included dorsalgia (16.7%), muscle weakness (15.6%), and abdominal pain (13.3%). PMU decreased by 38% post-index (adjusted odds ratio [OR] 0.62; 95% confidence interval [CI]: 0.30–1.28; p=0.198), mostly driven by a reduction in gabapentin and opioid use. Post-index, gabapentin and opioid utilization decreased by 67% (adjusted OR 0.33; 95% CI: 0.10–1.09; p=0.070) and 41% (adjusted OR 0.59; 95% CI: 0.19–1.90; p=0.379), respectively. In selumetinib-adherent patients (patients with ≥80% proportion of days covered [days covered/days in timeframe]; n=63), PMU decreased by 54% (adjusted OR 0.46; 95% CI: 0.18–1.16; p=0.100) versus no difference in non-adherent patients (adjusted OR 1.00; 95% CI: 0.30–3.37; p=1.000).

CONCLUSIONS: These data demonstrated a reduction in PMU in pediatric patients 6 months post-selumetinib initiation.