Comparison of the Efficacy of Placebo and Best Available Therapy for the Treatment of Myelofibrosis in the COMFORT Studies

Ruxolitinib (INC424), a potent and selective oral JAK1 and JAK2 inhibitor, has demonstrated rapid and durable reductions in splenomegaly and improved disease-related symptoms, role functioning, and quality of life (QoL) in 2 phase 3 studies in patients with myelofibrosis (MF) (the COMFORT studies). These studies compared ruxolitinib with either placebo or best available therapy (BAT). This analysis compares the efficacy outcomes between the placebo arm from COMFORT-I and the BAT arm from COMFORT-II.

COMFORT-I is a randomized (1:1), double-blind, multicenter study comparing ruxolitinib 15 or 20 mg twice daily (bid) with placebo, and COMFORT-II is a randomized (2:1), open-label, multicenter study comparing ruxolitinib 15 or 20 mg bid with BAT (investigator-selected therapy, including no treatment). Both studies met their primary end points with statistical significance (ruxolitinib vs control): the percentage of patients achieving ≥35% reduction in spleen volume at week 24 (COMFORT-I, P <.0001) and week 48 (COMFORT-II, P <.0001). QoL was measured using patient responses with the European Organisation for the Research and Treatment of Cancer (EORTC) QoL Questionnaire–Core 30 (QLQ-C30) as an exploratory end point in both studies.

In the COMFORT-I and COMFORT-II studies, 154 patients received placebo (ruxolitinib, n=155) and 73 patients received BAT (ruxolitinib, n=146), respectively, and were included in the primary efficacy analyses. The demographic and baseline characteristics were similar between the control arms of the 2 studies, including spleen size below the costal margin (mean [standard deviation, SD] 16.4 [6.27] cm and 15.8 [6.71] cm in placebo and BAT, respectively). Only 1 patient (0.7%) who received placebo and no patients who received BAT had a ≥35% reduction in spleen volume from baseline at week 24. The median spleen volume increased from baseline at week 24 in both the placebo and BAT groups and was numerically similar (placebo, 8.5% [range, −46.4% to 48.8%]; BAT, 5.1% [range, −33.3% to 29.7%]). In contrast, patients who received ruxolitinib had median reductions in spleen volume from baseline at week 24 of −33.0% (COMFORT-I) and −27.5% (COMFORT-II).

The QLQ-C30 provides a measurement of change in QoL and MF-related symptoms, including fatigue, pain, dyspnea, insomnia, and appetite loss. At 24 weeks, neither the placebo nor BAT arms had clinically meaningful changes from baseline (10 points [Osoba et al. J Clin Oncol. 1998]) in any of the QoL (decreases indicate worsening) or symptom scores (increases indicate worsening) (Table). Although differences existed between the placebo and BAT arms, the SDs are large, thus complicating comparisons between the 2 groups.

In the COMFORT studies, ruxolitinib demonstrated significantly greater reductions in spleen size compared with placebo or BAT. This post hoc analysis of the 2 studies shows that patients who received BAT in the COMFORT-II study had similar symptom and QoL responses and numerically similar increases in spleen size as those who received placebo in the COMFORT-I study. No clinically meaningful improvements in QoL or symptoms were seen on either the placebo or BAT arms. These new data strongly suggest that current therapies for MF provide little improvement in spleen size, symptoms, or QoL as compared with placebo.

Mesa:Incyte: Research Funding; Lilly: Research Funding; SBio: Research Funding; Astra Zeneca: Research Funding; NS Pharma: Research Funding; Celgene: Research Funding. Verstovsek:Incyte Corporation: Research Funding. Cervantes:Bristol-Myers-Squibb: Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Waltzman:Novartis: Employment. Mendelson:Novartis: Employment, Equity Ownership. Martin:Novartis Pharma AG: Employment. Sun:Incyte: Employment. Sandor:Incyte: Employment. Levy:Incyte Corporation: Employment, Equity Ownership. Harrison:Novartis: Honoraria; Incyte: Honoraria; S*Bio: Honoraria; Celgene: Honoraria; Sanofi Aventis: Honoraria.