Photo by Zak Hubbard
SAN DIEGO—Results of the PROUD-PV trial suggest ropeginterferon alfa-2b is safer than hydroxyurea (HU) for patients with polycythemia vera (PV).
In this phase 3 trial, ropeginterferon alfa-2b demonstrated non-inferiority to HU with regard to complete hematologic response (CHR).
Ropeginterferon alfa-2b also had a significantly better overall safety profile.
Unlike the patients who received HU, none of the patients on ropeginterferon alfa-2b developed secondary malignancies.
Heinz Gisslinger, MD, of the Medical University of Vienna in Austria, presented these results at the 2016 ASH Annual Meeting (abstract 475). The PROUD-PV study was sponsored by AOP Orphan Pharmaceuticals AG.
Dr Gisslinger noted that interferons have been successful in treating PV since the 1980s, although toxicities contribute to discontinuation rates of approximately 25%. Still, interferons are the only known drugs with the potential for disease modification by specific targeting of the malignant clone.
Ropeginterferon alfa-2b is a long-acting, mono-pegylated proline interferon with improved pharmacokinetic properties that allow for administration once every 2 weeks.
The goal of PROUD-PV was to determine how this drug stacks up against HU in both treatment-naive and HU-pretreated patients with PV.
“Our results from the first and largest, prospective, controlled trial of an interferon in polycythemia vera confirm previously reported efficacy,” Dr Gisslinger said.
“The observed safety and tolerability profile of ropeginterferon appears to be superior compared to previously reported data of interferon treatment. The unique disease-modification capability of interferon and its potential to improve progression-free survival hold promise for long-term benefit for patients.”
Patients and treatment
PROUD-PV enrolled 254 patients, and they were randomized to receive ropeginterferon alfa-2b (n=127) or HU (n=127). In both arms, 100% of patients were Caucasian, slightly more than half were female, and the median age was 60 (overall range, 21-85).
The median disease duration was 1.9 months in the ropeginterferon alfa-2b arm and 3.6 months in the HU arm. Thirty-seven percent (n=47) of patients in each arm had previously received HU.
The mean hematocrit was about 50% in both arms, the median spleen length was about 13 cm, about 90% of patients had a normal/slightly enlarged spleen, and the mean JAK2V617F burden was slightly more than 40%.
The median plateau dose was 450 µg in the ropeginterferon alfa-2b arm and 1250 mg in the HU arm.
A quarter (25.2%) of patients had dose reductions due to adverse events (AEs) in the ropeginterferon alfa-2b arm, as did 51.2% of patients in the HU arm. The 12-month discontinuation rate was 16.5% in the ropeginterferon alfa-2b arm and 12.6% in the HU arm.
Response
The study’s primary objective was to demonstrate non-inferiority of ropeginterferon alfa-2b compared to HU. For this, the researchers used the 12-month CHR rate. CHR was defined as normalization of red blood cell, white blood cell, and platelet counts (without phlebotomy).
At 12 months, in the intent-to-treat population, the CHR rate was 43.1% in the ropeginterferon alfa-2b arm and 45.6% in the HU arm (P=0.0028). In the per-protocol population, the CHR rate was 44.3% and 46.5%, respectively (P=0.0036).
The researchers therefore concluded that non-inferiority was demonstrated.
The study’s pre-specified primary endpoint was actually a composite of CHR and spleen length normality. However, this was confounded by the fact that the patients’ median spleen length was almost normal at baseline and the observed change was not clinically relevant.
In the intent-to-treat-population, CHR with spleen normality occurred in 21.3% of patients in the ropeginterferon alfa-2b arm and 27.6% of patients in the HU arm (P=0.2233).
Safety
The incidence of AEs was 81.9% in the ropeginterferon alfa-2b arm and 87.4% in the HU arm. The incidence of grade 3 AEs was 16.5% and 20.5%, respectively. And the incidence of treatment-related AEs was 59.6% and 75.6%, respectively (P<0.05).
There was a significantly higher incidence (P<0.01) of the following AEs in the HU arm than the ropeginterferon alfa-2b arm: anemia (24.4% vs 6.3%), leukopenia (21.3% vs 8.7%), thrombocytopenia (28.3% vs 15.0%), and nausea (11.8% vs 2.4%).
There was no significant difference in the incidence of fatigue—13.4% in the HU arm and 12.6% in the ropeginterferon alfa-2b arm.
Patients in the ropeginterferon alfa-2b arm had a significantly higher incidence of gamma-glutamyl transferase increase—14.2% vs 0.8% in the HU arm (P<0.01).
Patients in the ropeginterferon alfa-2b arm also had a higher—but non-significant—incidence of endocrine disorders (3.1% vs 0.8%), psychiatric disorders (1.6% vs 0%), cardiac/vascular disorders (3.1% vs 1.6%), and tissue disorders (1.6% vs 0%).
None of the patients in the ropeginterferon alfa-2b arm developed secondary related malignancies. In the HU arm, however, there were 2 cases of acute leukemia, 2 cases of basal cell carcinoma, and 1 case of malignant melanoma. (This includes data from the ongoing follow-up trial CONTINUATION-PV.)
Drug development
AOP Orphan Pharmaceuticals AG said that, in the coming months, it will submit data from PROUD-PV and the ongoing follow-up trial, CONTINUATION-PV, to obtain European marketing authorization for ropeginterferon alfa-2b.
PharmaEssentia plans to submit the same data to the US Food and Drug Administration.
PharmaEssentia discovered ropeginterferon alfa-2b and has licensed the rights for development and commercialization of the drug in myeloproliferative neoplasms to AOP Orphan Pharmaceuticals AG in Europe, the Commonwealth of Independent States, and Middle Eastern markets.
*Information presented at the meeting differs from the abstract.