A randomized phase II, open-label trial of orally administered SAR302503 in patients with polycythemia vera (PV) or essential thrombocythemia (ET) who are resistant or intolerant to hydroxyurea.
TPS6641 Background: Hydroxyurea is widely used to treat patients with high-risk PV and ET. However, some patients are either clinically resistant to hydroxyurea or have unacceptable side effects, supporting the need for active therapeutic options in this setting. SAR302503 is an orally administered selective JAK-2 inhibitor that reduced symptom burden and provided a durable clinical benefit, including a reduction in the JAK2V617F allele burden, with an acceptable safety profile in a Phase 1/2 trial of patients with primary myelofibrosis (MF), post-PV MF, or post-ET MF (J Clin Oncol 2011;29:789; Pardanani, ASH 2011; Abs 3838). Based on the results in MF, in October 2011 we initiated a Phase 2 trial to evaluate SAR302503 for the treatment of patients with PV and ET who are resistant or intolerant to hydroxyurea (NCT01420783; ARD12042). Methods: Eligibility criteria include age of at least 18 years, ECOG PS 0–2, and hydroxyurea resistant PV or ET as defined by European LeukemiaNet Consensus Criteria (Blood 2009;113:4829). Patients are being randomized (1:1:1) to receive 100, 200, or 400 mg of SAR302503 orally once daily in consecutive 28-day cycles for at least 8 cycles in the absence of progression or unacceptable toxicity. The primary end points will be assessed after the completion of 8 cycles and are: for PV, the proportion of patients maintaining a hematocrit below 45% without phlebotomy for at least 3 months; for ET, the proportion of patients with a platelet count lower than 400 × 109/L for at least 3 months. Secondary objectives include safety, response rate, pharmacokinetics, pharmacodynamics as measured by JAK2V617F allele burden and STAT3 phosphorylation inhibition, assessment of disease-related symptoms, and quality of life. Enrollment of the planned total of 90 patients is ongoing at approximately 45 sites globally. Twelve patients have been enrolled as of January 2012.