Long-term safety and effectiveness of ruxolitinib in patients with myelofibrosis in Japan: an observational study.

Aim: To evaluate the safety and effectiveness of ruxolitinib in patients with myelofibrosis (MF) in Japan.

Methods: A multicenter, observational study of patients who received ruxolitinib for MF from July 2014.

Results: Of 892 patients (mean age: 70 years, 45.9% primary MF, ruxolitinib treatment median duration, 541.0 days), 67.7% had adverse drug reactions (ADRs) and 31.5% had serious ADRs. The most frequent ADRs were anemia and decreased platelet count. Incidences of ADRs by time of onset were 57.7%, 20.3%, 14.4%, 11.1%, 11.3%, 9.0%, and 1.8% from the treatment initiation to Day 182, and every 6 months thereafter until Day 1,093 or later, respectively. ADRs of special interest included myelosuppression (46.8%), infections (17.6%), hepatic impairment (13.5%), hemorrhagic events (10.2%), cardiac failure (2.5%), interstitial lung disease (1.5%), malignancy (1.4%) and tuberculosis (0.5%). Incidences of common ADRs were similar between patients with hepatic or renal impairment and patients without hepatic or renal impairment. At 6 months, spleen responses and symptom improvement were observed in 26.2% and 52.0% of patients, respectively. Median overall survival was not reached.

Conclusion: In a real-world setting in Japan, ruxolitinib demonstrated a reasonable degree of effectiveness with no new safety concerns. Results were similar to those from clinical trials.