Real-World Analysis of Ruxolitinib Treatment Patterns and Outcomes Among Patients with Myelofibrosis

Background: Myelofibrosis (MF) is a myeloproliferative neoplasm characterized by bone marrow fibrosis, splenomegaly, cytopenias, and poor survival. Ruxolitinib (RUX) is the only approved treatment for Intermediate or High-risk MF. In a previous study, we have shown almost 1 in 3 patients initiating RUX had dose modifications during the first 3 months of treatment (Burton T et al. HemaSphere 2019). The objective of this study was to assess RUX treatment patterns among patients with MF.

Methods: This retrospective analysis used administrative claims data from a large US health plan to identify adults (aged ≥ 18 years) with ≥ 1 claim for RUX and ≥ 2 non-diagnostic medical claims for primary (International Classification of Diseases [ICD] 9th or 10th Revision [9/10]: 238.76, D47.4) or secondary MF (ICD-9/10: 289.83, D75.81) from January 1, 2012 to June 30, 2018. The first RUX claim on or after the first MF claim defined the index date. Included patients were continuously enrolled in a commercial or Medicare Advantage health plan for 3 months before the index date (pre-index period) and 6 months on or after the index date (post-index period). Clinical characteristics, MF-related treatments, health care resource utilization (HCRU), and costs were assessed during the pre- and post-index periods. Costs were adjusted to 2018 US dollars using the medical component of the Consumer Price Index. Cohorts were created based on the maximum (max) RUX daily dose observed during the 6-month post-index period: suboptimal max < 30 mg/day (SUB); and optimal max ≥ 30 mg/day (OPT). All variables were analyzed descriptively.

Results: Among 495 eligible patients, mean (SD) age was 69.4 (10.3) years; 54.1% were male; and 25% had a primary MF diagnosis code. Median initial RUX dose was 30 mg/day and patients continued with this dose for a mean (SD) of 70.0 (45.8) days. RUX dose was modified for 19.4% of patients during the 6-month post-index period, and the distribution of max RUX daily doses was: < 15 mg (13.7%), 15-29 mg (24.9%), 30-40 mg (55.8%), and > 40 mg (5.7%). Two groups based on max RUX dosing were further analyzed: 191 (38.6%) in the SUB cohort (< 30 mg), and 304 (61.4%) in the OPT cohort (≥ 30 mg). Patients in the SUB cohort were older than patients in the OPT cohort (SUB: mean 70.8 [SD 10.1] years; OPT: mean 68.5 [SD 10.3] years; P = 0.013), but the mean Charlson Comorbidity Index scores did not differ (SUB: mean 1.6 [SD 1.8]; OPT: mean 1.5 [SD 1.8]; P = 0.601). Rates of anemia were higher at baseline for the SUB cohort than the OPT cohort (SUB: 64.9%; OPT: 53%; P = 0.009). During the 6-month post-index period, compared with patients in the OPT cohort, patients in the SUB cohort had a higher proportion of thrombocytopenia (SUB: 31.4%; OPT: 22.7%; P = 0.03). Nearly half (45.5%) the sample used a supportive agent such as an androgen, systemic steroid, or erythropoiesis-stimulating agent during the post-index period (SUB: 48.2%; OPT: 43.8%; P = 0.34). With respect to HCRU and costs, the SUB cohort had a higher proportion of emergency department (ED) visits than the OPT cohort during baseline (SUB: 31.4%; OPT: 23.4%; P = 0.048); and baseline total mean (SD) all-cause costs were USD 18,079 (21,876) overall, USD 18,908 (24,411) for the SUB cohort, and USD 17,559 (20,145) for the OPT cohort (P = 0.523). During the 6-month follow-up period, 31.1% of patients had ≥ 1 ED visit (SUB: 35.1%; OPT: 28.6%; P = 0.131), 22.8% had ≥ 1 inpatient (IP) hospitalization (SUB: 24.6%; OPT: 21.7%; P = 0.455), and total mean (SD) all-cause costs were USD 94,498 (97,391) overall (SUB: USD 93,289 [115,418]; OPT: USD 95,258 [84,315]; P = 0.839).

Conclusion: In this study, patients with MF treated with RUX experienced significant disease burden and high costs, regardless of dose. Both anemia and thrombocytopenia were observed along with nearly half of patients using a supportive agent. Given the large proportion of patients with a dose adjustment, suboptimal dosing, and an IP hospitalization, there continues to be a need for additional therapeutic options for patients with MF.