Long-term safety and efficacy of ropeginterferon alfa-2b in Japanese patients with polycythemia vera

Abstract

Ropeginterferon alfa-2b (ropegIFN), a new-generation interferon-based agent, has been approved in Japan for patients with polycythemia vera (PV) who are ineligible for or respond inadequately to conventional treatment. However, long-term outcomes with ropegIFN in Japanese patients have not been reported. This extension of a phase 2 study of ropegIFN in Japanese patients with PV aimed to determine its long-term safety/efficacy, and changes over time in JAK2 V617F allele burden. Here, we report data from the phase 2 study and subsequent extension over a period of 36 months. The primary endpoint was the complete hematologic response (CHR) maintenance rate without phlebotomy (hematocrit value < 45% without phlebotomy during the previous 12 weeks, platelet count ≤ 400 × 10⁹/L, and white blood cell count ≤ 10 × 10⁹/L). The CHR maintenance rates were 8/27 (29.6%), 18/27 (66.7%), and 22/27 (81.5%) at 12, 24, and 36 months, respectively. No thrombotic or hemorrhagic events occurred. The median allele burden change from baseline was - 74.8% at 36 months. All patients experienced adverse events; 25/27 (92.6%) experienced adverse drug reactions (ADRs), but no serious ADRs or deaths occurred. This interim analysis demonstrated the safety and efficacy of ropegIFN over 36 months in Japanese patients with PV.

Keywords: JAK2 V617F allele burden; Hematologic response; Molecular response; Polycythemia vera; Ropeginterferon alfa-2b.

Fig. 1

Maintenance of CHR with/without prior HU use (intention-to-treat population, central laboratory data). CHR, complete hematologic response; HU, hydroxyurea; RR, relative risk

Fig. 2

Maintenance of CHR by disease duration (intention-to-treat population, central laboratory data). CHR, complete hematologic response; RR, relative risk

Fig. 3

JAK2 V617F allele burden (intention-to-treat population). The box shows the median line and upper and lower quartiles, whiskers represent the range. Data at week 148 or week 160 are shown as 36 months, as one patient had missing data at week 148; therefore, week 160 data were used for this patient