Interim Analysis Finds Benefits of Ruxolitinib to Treat PV in Patients Intolerant/Resistant to Hydroxyurea

Patients with polycythemia vera (PV) who are resistant or intolerant to hydroxyurea (HU) may benefit from being treated with ruxolitinib, according to an abstract presented at the European Hematology Association’s annual meeting.

The findings presented were the 52-week interim results from an ongoing phase 3 study. The observational, noninterventional study included 352 patients with PV who were treated with ruxolitinib in 88 European sites. The interim analysis included 60 patients with PV who were resistant/intolerant to HU and had been prescribed or had already initiated treatment with ruxolitinib.

The patients in the study had a mean duration of PV of 4.9 years before they joined the study; 30% had a medical history of infections, 12% had a history of secondary neoplasms (SNP), 25% had a history of thromboembolic events of interest (TEs), and 7% had a history of bleeding. At baseline, 18% had ongoing infections, 10% had ongoing SNP, and 17% had ongoing TEs.

At baseline, 55 patients had hematocrit (HCT) measured, 57 patients had white blood cell counts measured, and 22 had spleen measurements. Thirty-seven (62%) of patients in the interim analysis had required phlebotomies (PHB) 1 year before ruxolitinib treatment, and 24 of them needed 3 or more PHB.

During treatment, HCT levels dropped from 44% at baseline to 40% at week 52, with levels dropping more rapidly in the first 12 weeks before stabilizing. The percentage of patients who were PHB-independent also rose from 38% in the year before ruxolitinib treatment to 88% during the year of treatment. PHB frequency also dropped and the percentage of patients needing 3 or more PHB dropped from 40% in the year before treatment to 5% in the year during treatment.

Most (80%) of the patients remained on ruxolitinib without any discontinuation. The grade 3/4 adverse events during the study were infections (5%), SNP (2%), and TEs (3%).

According to the authors, the results of the interim analysis confirmed findings from previous interventional studies of ruxolitinib in PV. They noted that full data will become available as the study of the full 352 patients concludes after 24 months of follow-up.

Reference

Te Boekhorst PAW, Theocharides A, Alvarez-Larrán A, et al. Ruxolitinib in PV patients resistant and/or intolerant to hydroxyurea: interim analysis of a European multi-centric observational study. Presented at: EHA25 2020; June 11-21, 2020; Abstract EP1115.