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Ruxolitinib versus best available therapy for ET intolerant or resistant to hydroxycarbamide in a randomized trial

Claire N. Harrison, Adam J. Mead, Anesh Panchal, Sonia Fox, Christina Yap, Emmanouela Gbandi, Aimee Houlton, Samah Alimam, Joanne Ewing, Marion Wood, Frederick Chen, Jason Coppell, Nicki Panoskaltsis, Steven Knapper, Sahra Ali, Angela Hamblin, Ruben Scherber, Amylou C. Dueck, Nicholas C.P. Cross, Ruben Mesa and Mary Frances McMullin

Key points

  • Ruxolitinib showed no significant improvement for attainment of either CR or PR over BAT within the first year of therapy in high-risk ET.

  • Ruxolitinib significantly improved some disease-related symptoms but rates of thrombosis, hemorrhage or transformation were not different.

Abstract

Treatments for high-risk essential thrombocythemia (ET) address thrombocytosis, disease-related symptoms, as well as risks of thrombosis, hemorrhage, transformation to myelofibrosis and leukemia. Patients resistant/intolerant to hydroxycarbamide (HC) have a poor outlook. MAJIC (ISRCTN61925716) is a randomized phase II trial of ruxolitinib (JAK1/2 inhibitor) vs Best Available Therapy (BAT) in ET and polycythemia vera (PV) patients resistant or intolerant to HC. Here findings of MAJIC-ET are reported, where the modified intention-to-treat population included 58 & 52 patients randomized to receive ruxolitinib or BAT respectively. There was no evidence of improvement in complete response within 1 year reported in 27 (46.6%) patients treated with ruxolitinib vs 23 (44.2%) with BAT (P=.40). At 2 years rates of thrombosis, hemorrhage and transformation were not significantly different, however some disease-related symptoms improved in patients receiving ruxolitinib relative to BAT. Molecular responses were uncommon; there were two complete molecular responses (CMR) and one partial molecular response (PMR) in CALR positive ruxolitinib-treated patients. Transformation to myelofibrosis occurred in one CMR patient, presumably due to the emergence of a different clone raising questions about the relevance of CMR in ET patients. Grade 3&4 anemia occurred in 19% & 0% of ruxolitinib vs 0% (both grades) BAT arm, grade 3&4 thrombocytopenia in 5.2% & 1.7% of ruxolitinib vs 0% (both grades) of BAT treated patients. Rates of discontinuation or treatment switching did not differ between the two trial arms. The MAJIC-ET trial suggests that ruxolitinib is not superior to current second-line treatments for ET.

  • Submitted May 24, 2017.
  • Accepted July 24, 2017.