Baseline Characteristics and Symptom Burden in RESPONSE: A Randomized, Open-Label, Phase 3 Study of Ruxolitinib In Polycythemia Vera Patients Resistant to or Intolerant of Hydroxyurea

Polycythemia vera (PV) is the most common of the myeloproliferative neoplasms and is characterized by elevated hematocrit requiring phlebotomy, splenomegaly, a variety of symptoms and increased thrombotic risk. Ruxolitinib, a JAK1/JAK2 inhibitor, was well tolerated and achieved rapid and durable clinical responses in a phase 2 study of patients (pts) with PV who were resistant to or intolerant of hydroxyurea (HU). Pts experienced phlebotomy independence, resolution of splenomegaly, and improvements in white blood cell (WBC) counts, platelet (PLT) counts, and disease-related symptoms. Here, we describe the baseline (BL) characteristics and symptom burden of pts in a phase 3 study of ruxolitinib in pts with PV who are resistant to or intolerant of HU.

RESPONSE is a randomized (1:1), open-label, phase 3 study (NCT01243944) comparing the efficacy and safety of ruxolitinib with best available therapy (BAT) in pts with PV who are resistant to or intolerant of HU (modified European LeukemiaNet criteria), have splenomegaly, and require phlebotomy for inadequate hematocrit (Hct) control. Fourteen disease-related symptoms were assessed on a scale of 0 (absent) to 10 (worst imaginable) using the modified Myeloproliferative Neoplasm Symptom Assessment Form (MPN-SAF). Blinded data are presented here.

BL demographic data are available for the 222 enrolled pts (Table). Apart from HU, other common prior medications for PV included interferons (15%), PLT aggregation inhibitors (10%), alkylating agents (3.6%), alkyl sulfonates (3.2%), pyrimidine analogues (1.8%), and nitrosoureas (1.4%). The majority of pts (54.5%) had 1 phlebotomy within 12 weeks prior to screening; 23.9% had 2 and 17.1% had 3 or more phlebotomies. RESPONSE BL demographics are generally similar in terms of age (60 years vs 57-67); sex (66% male vs 58%-68%); Hct (44% vs 45%-48%); and platelets (419 x 10⁹/L vs 320-429 x 10⁹/L) to other PV studies including trials of givinostat (Finazzi BJH 2013) and AOP2014 (Gisslinger ASH 2012) and the ECLAP-PV (Marchioli JCO 2005) and CYTO-PV studies (Marchioli NEJM 2012). At the time of writing, BL symptom data from the MPN-SAF were available for 164 pts (Table). Pts in this study reported a similar symptom burden as PV pts from a large study of pts with MPNs (Emanuel JCO 2012; N = 1425; PV, n = 538), including similar mean scores for early satiety, abdominal discomfort, concentration problems, night sweats, itching, and tiredness/fatigue. In addition, prior therapy may have adversely affected BL symptom burden, as many of these symptoms (concentration problems, night sweats, fatigue) have been shown to be worsened by the use of conventional therapy to strictly control Hct (< 45%) and cardiovascular risk (Emanuel EHA 2013). BL MPN-SAF symptom data for all 222 pts will be presented. In addition, correlations between BL EORTC QLQ-C30 and MPN-SAF scores will be presented.

Demographic and BL symptom data from the RESPONSE study demonstrated that pts with HU refractory or intolerant PV have a significant disease burden that includes a variety of symptoms. These findings are consistent with those of Emanuel (JCO 2012), which showed that pts with PV have a significant symptom burden and a reduced quality of life. Pts with PV in the RESPONSE study are representative of those who have been studied in other clinical trials for the treatment of PV.

Vannucchi:Novartis: Honoraria, Membership on an entity’s Board of Directors or advisory committees. Off Label Use: Ruxolitinib, a JAK1/JAK2 inhibitor, has been approved by the US Food and Drug Administration for the treatment of intermediate- or high-risk MF and by the European Commission and Health Canada for the treatment of disease-related splenomegaly or symptoms in adult patients with MF. Here, we describe the baseline (BL) characteristics and symptom burden of patients in a phase 3 study of ruxolitinib in patients with PV who are resistant to or intolerant of HU. Kiladjian:Novartis: Honoraria; Shire: Honoraria. Durrant:Novartis: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Sanofi: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding. Pane:Novartis: Consultancy, Honoraria; Shire: Honoraria. Harrison:Novartis: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding, Speakers Bureau; Sanofi: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Speakers Bureau; YM Bioscience: Honoraria, Membership on an entity’s Board of Directors or advisory committees; Celgene: Honoraria; Shire: Speakers Bureau; SBio: Honoraria, Membership on an entity’s Board of Directors or advisory committees; Gilead: Honoraria, Membership on an entity’s Board of Directors or advisory committees. He:Incyte: Employment. Leopold:Incyte: Employment, Stock options Other. Li:Novartis: Employment, Equity Ownership. Pirron:Novartis: Employment, Equity Ownership. Lawniczek:Novartis: Employment. Verstovsek:Incyte: Research Funding.