Randomized Trial of Pegylated Interferon Alfa-2a Versus Hydroxyurea in Polycythemia Vera (PV) and Essential Thrombocythemia (ET)

The Philadelphia chromosome negative myeloproliferative neoplasms (MPN) are a group of clonal hematological malignancies that are characterized by a chronic course which can be punctuated by a number of disease related events including thrombosis, hemorrhage, pruritis and leukemic transformation. These disorders include Polycythemia Vera (PV), Essential Thrombocythemia (ET) and Primary Myelofibrosis (PM). Recently an acquired somatic mutation in the intracellular kinase, JAK2 (JAK2V617F) has been observed in 95% of patients with PV, 50% of patients with ET and 50% of patients with primary myelofibrosis. At present the chemotherapeutic agent hydroxyurea is the standard of care for high risk patients with PV. Concern exists about prolonged use of this drug leading to leukemia and the inability of hydroxyurea to eliminate the malignant clone. Interferon (rIFN -2b), is a drug that appears to be non-leukemogenic, and may have a preferential activity on the malignant clone in PV, as suggested by cytogenetic remissions obtained in patients treated with rIFN -2b. Several investigators recently reported that patients with PV treated with rIFN -2b had lower JAK2V617F allele burdens as compared to a control group that included patients treated with phlebotomy, hydroxyurea, or anagrelide, or who remained untreated. The results confirm the hypothesis that rIFN -2b preferentially targets the malignant clone in PV and raises the possibility that the JAK2V617F allele burden, and a reversion of clonal hematopoiesis monitored in females by expression of X-chromosome polymorphic alleles maybe useful in monitoring minimal residual disease in PV patients. Pegylated Interferon Alfa-2a (PEGASYS) has been demonstrated in phase II trials of patients with PV and ET to have clinical efficacy as measured by normalization of myeloproliferation, lack of vascular events while on therapy, and a decrease in the JAK2V617F allele burden. Overall the tolerability of the therapy was good, with each of these trials having a dropout rate secondary to toxicity of less than 10% of those enrolled. Although dropout rates for toxicity were low, that is not to say the therapy was without symptomatic toxicity, and indeed a spectrum of toxicities might be encountered and need to be weighed in the analysis of the net clinical benefit patients experience on a clinical trial with Pegylated Interferon Alfa-2a. A new MPN assessment form will be utilized in this study. This 19 item instrument includes a previously validated 9 item brief fatigue inventory (BFI), symptoms related to splenomegaly, inactivity, cough, night sweats, pruritus, bone pains, fevers, weight loss, and an overall quality of life assessment. The instrument yields an independent result for each symptom (fatigue is a composite score), as this methodology (of linear analog scale assessment \[LASA\]) has proven very valid in the past. This instrument was validated prospectively (by comparison to a panel of instruments each containing an aspect of the MPN-SAF) for administration at a single time point. This is a randomized trial between hydroxyurea and Pegylated Interferon Alfa-2a, it is an open label clinical trial in two independent disease strata: (1) high risk polycythemia vera and (2) high risk essential thrombocythemia.