[Efficacy and Safety of Ruxolitinib in Polycythemia Vera]

To evaluate the efficacy and safety of ruxolitinib in patients with polycythemia vera (PV).

The clinical data of patients with PV treated with ruxolitinib in Peking Union Medical College Hospital from January 1, 2013 to December 31, 2019 were retrospectively analyzed. The starting dose of oral ruxolitinib was 10 mg twice daily and could be increased after 3 months of treatment if hematocrit (HCT) control was not achieved. HCT control was defined as HCT<45% in the absence of phlebotomy.

Thirty-three patients (17 males and 16 females) were treated with ruxolitinib at a median age of 50 (21-72) years. JAK2V617F and JAK2exon12 alleles were detected in 31 and 2 patients, respectively. Before treatment, median hemoglobin level was 187 (166-208) g/L, median white blood cell and platelet level was 10.4 (5.0-15.8)×10⁹/L and 457(237-677)×10⁹/L, respectively. Totally 17 patients (51.5%) who were resistant to or intolerant of hydroxyurea were treated with ruxolitinib as second-line therapy, and 16 patients (48.5%) were treated with ruxolitinib as first-line therapy voluntarily. The median time since PV diagnosis to treatment of ruxolitinib was 47 (3-188) months. By December 31, 2019, all the patients continued to receive ruxolitinib. The median duration of ruxolitinib exposure was 19 (2-91) months. Both in the first-line therapy group and second-line therapy group, 15 cases (accounting for 93.8% and 88.2%, respecitvely) achieved HCT control. The median time from start of therapy to HCT control was 2.2 (0.8-11.6) months. One patient (3.0%) had disease progression after HCT control. The most common hematologic adverse events included anemia and thrombocytopenia, according to CTCAE classification, including 1 case of grade 1 anemia (3.0%) and 1 case of grade 2 thrombocytopenia (3.0%). There was no thromboembolic event occurred during the therapy of ruxolitinib.

The remission rate of HCT in PV patients treated with ruxolitinib is high, and adverse reactions are rare. Ruxolitinib is effective in HCT control and generally well tolerated in patients with PV.