Patients With PV Who Switched from Hydroxyurea to Ruxolitinib Had Improved Hematocrit, White Blood Cell Counts

Real-world research published in Blood demonstrated that when patients with polycythemia vera (PV) switched from treatment with hydroxyurea to ruxolitinib (Jakafi; Incyte Corp.), they experienced an improved hematocrit and white blood cell count control. Additionally, the study investigators observed that the frequency of phlebotomy was numerically lower during treatment with ruxolitinib compared with hydroxyurea.

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PV is a myeloproliferative neoplasm that often presents with elevated hemoglobin and/or hematocrit levels. According to current National Comprehensive Cancer Network guidelines, it is recommended that all patients maintain a hematocrit level below 45% with phlebotomy or cytoreductive treatment, such as hydroxyurea. For this analysis, the investigators aimed to describe treatment patterns, blood count control, and the use of phlebotomy in patients with PV who had switched from hydoxyurea to ruxolitinib at community practices within the US.

This retrospective study enrolled a total of 443 adult patients with PV who switched from treatment with hydroxyurea to ruxolitinib. All patients were newly diagnosed and had 2 or more postdiagnosis visits during the study period, which was January 2014 to May 2023. Additionally, all patients were enrolled from the Integra Precision Q electronic health record database. Patients who switched from hydroxyurea to ruxolitinib either as a first line of treatment to second line, or from second line to third line, were characterized in this analysis.

The investigators defined elevated blood counts as hematocrit of 45% or higher, white blood cell count of 11×10⁹ per liter or higher, or platelet count over 400, which aligns with the European LeukemiaNet response criteria and findings from the CYTO-PV study (NCT01645124). In addition, treatment duration and time between treatments were based on the dates of prescription refills.

Among the 443 patients with a mean age of 68.8 years (at the time of hydroxyurea initiation) enrolled in the study, 317 switched from hydroxyurea to ruxolitinib as their second line of treatment and the remaining 126 received it as a third line. Additionally, approximately 10.6% (n = 47) of patients received ruxolitinib as a combination therapy, either in combination with hydroxyurea (97.9%, n = 46) or with pegylated-interferon (2.1%, n = 1). Most of the patients (79.7%) were 60 years of age or older and were White (62%). Mean time from PV diagnosis to hydroxyurea initiation was about 9.3 months, and from PV diagnosis to ruxolitinib initiation was about 31.0 months (second line: 27.5 months; third line: 39.8 months).

The investigators observed that the median duration of hydroxyurea treatment was about 9.7 months (IQR 3.6-27.5 months) for the first line of therapy and 9.2 (IQR 3.9-25.0 months) for the second line. Additionally, the time between end date of hydroxyurea treatment and initiation of ruxolitinib was about 4.3 months for first to second line, and 3.1 months for second to third line. Median duration of ruxolitinib treatment was 10.5 months (IQR 4.1-28.7 months) for second line and 12.2 months (IQR 5.0-29.4 months) for third line. The median time from ruxolitinib initiation to the end of the study period was 20.4 months (IQR 9.1-39.5 months). At that time, approximately 38.4% (n = 170) of patients continued to receive ruxolitinib (initiation at second line: 37.2%; initiation at third line: 41.3%).

Further, among those who had switched to ruxolitinib, 178 patients had hematocrit data available at all 4 time points, of which about 41.6% (n = 74) had elevated levels following hydroxyurea treatment and prior to ruxolitinib initiation. At the time of ruxolitinib initiation, about 22.5% (n = 40), 18.0% (n = 32), and 14.6% (n = 26) of patients had elevated hematocrit levels at the 3-, 6-, and 12-month periods, respectively.

Of 192 patients with available white blood cell data, approximately 54.7% (n = 105) had elevated levels following hydroxyurea and before ruxolitinib initiation, with elevated levels observed in 40.6% (n = 78), 46.4% (n = 89), and 45.8% (n = 88) of patients at the 3-, 6-, and 12-month periods from ruxolitinib initiation, respectively. Additionally, 200 patients had available PLT data of which 42.5% (n = 85) had elevated platelets with elevations present in 46.0% (n = 92), 46.5% (n = 93), 42.5% (n = 85) at the 3-, 6-, and 12-month periods from ruxolitinib initiation, respectively.

Further, patients had high mean phlebotomies per patient per year when receiving treatment with hydroxyurea. Patients who initiated ruxolitinib as a second line or third line of treatment presented a mean of 7.2 and 5.0, respectively, during hydroxyurea treatment, compared with 3.8 and 3.6 during ruxolitinib treatment. With these findings, the investigators suggest that there are clinical benefits for patients with PV if they switch to ruxolitinib following inadequate disease control while receiving hydroxyurea.

REFERENCE

Pemmaraju N, Yu J, Vasudevan A, Qureshi H, Braunstein EM, Chojecki AL. Real-world treatment patterns and blood count control in patients with polycythemia vera who switched from hydroxyurea to ruxolitinib. Blood. 2024;144(Supplement 1):3813. doi:10.1182/blood-2024-205193