Mean Percent Change From Baseline to Week 24 ± SD SV TSS Ruxolitinib Placebo Primary MF -29.9 ± 17.5 +8.5 ± 16.7 -38.5 ± 54.3 +41.7 ± 92.0 Post-Polycythemia Vera MF -37.3 ± 20.9 +5.9 ± 14.5 -54.9 ± 41.5 +27.2 ± 105 Post-Essential Thrombocythemia MF -27.0 ± 17.4 +11.1 ± 11.2 -49.9 ± 45.1 +73.7 ± 112 High Risk -30.9 ± 19.5 +7.7 ± 15.8 -41.5 ± 52.2 +48.7 ± 94.8 Intermediate-2 Risk -32.8 ± 18.4 +9.1 ± 14.5 -53.5 ± 43.2 +28.8 ± 107 Age ≤65 years -31.1 ± 18.8 +12.7 ± 15.6 -48.1 ± 46.6 +28.6 ± 73.0 Age >65 years -32.2 ± 19.3 +6.3 ± 14.9 -45.0 ± 50.6 +47.7 ± 109 V617F Positive -34.6 ± 19.8 +8.1 ± 16.5 -52.6 ± 44.9 +42.8 ± 98.6 V617F Negative -23.8 ± 14.2 +8.4 ± 8.5 -28.1 ± 55.5 +37.2 ± 105 Baseline Palpable Spleen Length ≤10cm -26.8 ± 19.1 +13.0 ± 11.7 -28.5 ± 56.6 +39.1 ± 116 Baseline Palpable Spleen Length >10cm -32.9 ± 18.9 +6.9 ± 15.9 -51.1 ± 45.4 +42.4 ± 95.5 Baseline Hb≥10g/dL -33.4 ± 18.7 +7.6 ± 16.1 -47.0 ± 49.6 +27.2 ± 99.7 Baseline Hb<10g/dL -28.3 ± 19.2 +8.9 ± 14.3 -45.6 ± 47.1 +63.8 ± 95.6