Ruxolitinib Reduces Spleen Size and Improves Disease-Related Symptoms in Patients with Lower-Risk MF

Although there have been several trial-based studies on the use of ruxolitinib in patients with lower-risk myelofibrosis (MF), Keith L. Davis, MA, Senior Director of Health Economics at RTI Health Solutions and colleagues sought to conduct a study in the real-world setting.

Based on the positive results of previous studies in patients with intermediate-2 and high-risk MF, the authors conducted a retrospective assessment to determine whether patients with lower-risk MF could benefit from ruxolitinib therapy.

Using anonymized medical record data collected by 49 US hematologists and oncologists in January 2014, Mr Davis and colleagues measured changes in spleen size and disease-related symptoms in patients with lower-risk MF receiving ruxolitinib. Eligibility criteria for study inclusion included patients with a diagnosis of lower-risk MF (International Prostate Symptom Score of 0 [Lower-risk] or 1 [intermediate-1 risk]), receiving initial therapy with ruxolitinib ≥ 3 months prior to the date of medical record abstraction, aged ≥ 18 years at time of treatment initiation, having a medical history of MF, and having never been enrolled in a previous interventional MF-related trial.

Overall, 108 patients were included in the study; of them, 25 patients with low-risk MF and 83 with intermediate-1-risk disease. The majority of patients in both groups were men, and had primary MF at initial diagnosis. At the time of their MF diagnosis, 53% of the patients with intermediate-1-risk MF and 66% of patients with low-risk MF had moderate-to-severe splenomegaly (palpable spleen >10 cm). In addition, most patients were still receiving ruxolitinib therapy at the time of medical record abstraction

Patients with low-risk MF taking ruxolitinib had a substantial improvement in spleen size; moderate or severe splenomegaly decreased from 64% at the time of MF diagnosis to 16% at best response. In total, 78% of patients with low-risk disease demonstrated a decrease in spleen size from time of MF diagnosis to best response during ruxolitinib treatment, and 68% had a decrease from time of ruxolitinib initiation to best response. Findings were similar for the patients with intermediate-1-risk disease

Overall in both groups, symptom severity shifted distinctly toward a more favorable, less severe profile from time of MF diagnosis to the time of best response during treatment with ruxolitinib, Mr Davis and colleagues observed. The proportion of patients with fatigue-which was the most common reported symptom-decreased from 90% and 76% at MF diagnosis to 37% and 42% at best ruxolitinib response in patients with low-risk and intermediate-1-risk MF, respectively.

"Findings from this study indicated that patients with lower-risk MF in routine clinical practice may benefit from ruxolitinib treatment, specifically for spleen size reduction and improved splenomegaly-related and constitutional symptoms," the investigators concluded. "Furthermore, ruxolitinib has been shown to prolong overall survival in patients with intermediate-2 or high-risk MF and to reduce the risk of death among high-risk patients receiving ruxolitinib to that of intermediate-2-risk patients receiving placebo or best available therapy."

According to the study authors, these results have the potential to change the clinical course of this patient population. Further research is warranted to evaluate the effect of ruxolitinib in patients with intermediate-1 or low-risk MF.

Reference

Davis KL, Cote I, Kaye JA. Real-world assessment of clinical outcomes in patients with lower-risk myelofibrosis receiving treatment with ruxolitinib. Adv Hematol. 2015;2015:848473.