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An expanded treatment protocol study has shown that ruxolitinib was safe and effective in patients with polycythemia vera who were neither candidates for hydroxyurea nor enrollment in another ongoing clinical trial. The findings from this study were published in Leukemia and Lymphoma.1
Polycythemia vera is associated with activating JAK2 mutations, resulting in constitutive activation of the JAK/STAT pathway. Common clinical manifestations of the disease, including thrombosis, bleeding, and splenomegaly, are a consequence of myeloproliferation, particularly erythrocytosis. In addition, other symptoms, including night sweats, pruritus, and bone pain can result in substantial quality of life detriments.
The main treatment goal for patients with this disease is to minimize associated clinical sequelae by regulating the hematocrit level. Although hydroxyurea is the mainstay of treatment for polycythemia vera, some patients are resistant to, or intolerant of, this approach.
Ruxolitinib, a JAK kinase inhibitor, was approved by the US Food and Drug Administration (FDA) for the treatment of patients with polycythemia vera who are hydroxyurea resistant or intolerant based on results of the RESPONSE studies (ClinicalTrials.gov Identifier: NCT01243944) .2,3
In this study, initiated prior to FDA approval of ruxolitinib, researchers sought to provide early access to the drug. The primary endpoint was safety, with secondary endpoints including change in hematocrit level, as well as patient-reported outcomes.
Inclusion criteria in the single-arm, open-label, phase 3b, expanded treatment protocol study (ClinicalTrials.gov Identifier: NCT02292446) were adults, diagnosis of polycythemia vera, intolerance/resistance to hydroxyurea, and ineligibility for another standard treatment option or enrollment in another clinical study.
Baseline characteristics of the 161 patients enrolled in the study included a median age of 66 years, a hematocrit level of 45% or higher in 51.5% of patients, and a history of a disease-related thromboembolic event in 32.9% of patients. All but 1 of these patients had received prior treatment with hydroxyurea.
