OBJECTIVES: Selumetinib received U.S. Food and Drug Administration approval on April 10, 2020 for the treatment of pediatric patients aged ≥2 years with neurofibromatosis type 1 (NF1) and symptomatic, inoperable plexiform neurofibromas (PN). The primary objective of this study was to evaluate real-world adherence, persistence/discontinuation, and re-initiation among pediatric patients treated with selumetinib.

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 (baseline period) and ≥6 months after (follow-up period) first selumetinib prescription (index) and ≥2 selumetinib prescription fills (4/10/2020–12/31/2022). Proportion of days covered (PDC; days covered/days in timeframe) was assessed to evaluate adherence (PDC ≥80%). Time-to-discontinuation (TTD; days from first fill to last day covered) and time-to-re-initiation of selumetinib (after a gap of ≥84 days) were determined using Kaplan–Meier analyses.

RESULTS: Overall 90 patients with ≥2 selumetinib fills were identified (mean [standard deviation] age, 12 [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. Mean PDC was 83.6% and 70% of patients were adherent. Younger patients (aged 2–5 years; n=8) were generally more adherent than those aged 6–11 (n=29) and 12–18 years (n=53; PDC ≥80%: 87.5% of n=8 vs. 72.4% of n=29 vs. 66.0% of n=53, respectively). Patients were 10% less likely to be adherent than those 1 year younger (odds ratio 0.90; 95% confidence interval: 0.80–1.0; p=0.063). At 6 months post-index, the probability of discontinuation was 14.5% (median TTD 2.25 years). Approximately 20% (n=7) of patients who discontinued later re-initiated, most (~80%) within 6 months of discontinuation.

CONCLUSIONS: Most patients were adherent to selumetinib treatment and the probability of adherence decreased with age. Approximately 20% of patients who discontinued selumetinib subsequently re-initiated, mostly within 6 months.