MADRID—Long-term maintenance with ropeginterferon alfa-2b is feasible, effective, and well-tolerated in patients with polycythemia vera (PV), according to researchers.
In the ongoing phase 1/2 PEGINVERA study, patients have received ropeginterferon alfa-2b for a median of 4 years.
After the first 2 years, patients switched from bi-weekly dosing to receiving ropeginterferon alfa-2b once every 4 weeks.
None of the patients discontinued treatment after the switch, and many were able to maintain their best response.
Most adverse events (AEs) were mild, although there were several severe treatment-related AEs.
These results were presented in a poster (abstract P707) at the 22nd Congress of the European Hematology Association (EHA). The research was funded by AOP Orphan Pharmaceuticals AG.
The trial enrolled 51 patients, but the researchers reported results in the 29 patients who had completed 2 years of treatment and switched from bi-weekly dosing to receiving treatment once every 4 weeks.
All 29 patients remained on the 4-week schedule with a median observation period of roughly 2 years. The median monthly dose was 308 μg before the switch and 165 μg after.
At study entry, the patients’ median age was 58 (range, 40-80), and 76% were male. Their median spleen length was 12.8 cm (range, 8.0-22.0), and 34% of patients had prior treatment with hydroxyurea.
Patients’ median hematocrit was 45.40% (range, 36.9-53.8), their median platelet count was 431 G/L (range, 225-1016), their median leukocyte count was 11.1 G/L (range, 4.7-30.9), and their median JAKV617F allelic burden was 78% (range, 2-91.5).
More than 80% of patients achieved a hematologic response, with more than 50% achieving a complete hematologic response. The same percentage of patients maintained their best hematologic response before and 6 months after switching to the 4-week schedule—51.7%.
More than 80% of patients achieved a molecular response, with nearly 20% achieving a complete molecular response. The percentage of patients maintaining their best molecular response was 62.1% before switching to the 4-week schedule and 58.6% 6 months after the switch.
The researchers said changes in hematocrit, platelet count, leukocyte count, and spleen size after the switch were “minimal and without clinical relevance.”
The median hematocrit changed from 42.3% to 42.6%, the median platelet count changed from 201.0 x 109/L to 211.9 x 109/L, the median leukocyte count changed from 5.0 x 109/L to 5.6 x 109/L, and the median spleen size changed from 12.8 cm to 12.4 cm.
The need for phlebotomy did not change, with 24.1% of patients requiring phlebotomy both before and 6 months after the switch.
The researchers also noted that ropeginterferon alfa-2b decreased mutant JAK2 allele burden in all of the patients over time, with the strongest effect observed in the second year of treatment.
After 2 years, most patients had a burden below 10%, and this was not affected by the change in dosing.
There were no cases of progression to myelofibrosis or leukemic transformation.
Seventy-one percent of AEs were mild, and 40.4% were considered likely related to ropeginterferon alfa-2b. The most frequent treatment-related AEs were arthralgia (29.4%) and fatigue (21.6%).
There were 34 severe AEs, 11 of which were related to ropeginterferon alfa-2b.