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Revised assessment of response and long-term discontinuation rates among 111 patients with myelofibrosis treated with momelotinib or ruxolitinib

Leukemia volume 29, pages 498–500 (2015)Cite this article

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Current estimates of response to JAK inhibitor therapy, in patients with myelofibrosis (MF), are based on the 2006 response criteria published by the International Working Group for Myeloproliferative Neoplasms (MPN) Research and Treatment (IWG-MRT).1 These criteria were recently revised by the IWG-MRT and the European LeukemiaNet (ELN), with the intent to include stricter definitions of red cell transfusion dependency and independency, objective measurement of spleen size and formal assessment of response in disease-related symptoms.2 In addition, the 2013 revised criteria require at least 12 weeks of response duration and a clinical improvement (CI) response category that accounts for the absence of concomitant deterioration in severity of cytopenias.2 The latter is particularly relevant to JAK inhibitor therapy, because their value in reducing spleen size is often antagonized by their adverse effect on hemoglobin level and platelet count.3, 4, 5, 6

The currently available drugs are incapable of inducing complete (CR) or partial (PR) remission in MF. CR or PR in MF requires a hemoglobin level ⩾10 g/dl without transfusion, platelet count ⩾100 × 109/l, neutrophil count ⩾1 × 109/l and resolution of disease-related symptoms, palpable hepatosplenomegaly and leukoerythroblastosis; in addition, reversal of bone marrow fibrosis and normalization of bone marrow cellularity is required for CR or ‘PR with incomplete recovery of blood counts’.2 In other words, ‘CI’ is currently the maximum benefit that one derives from drug treatment in MF, including JAK inhibitor therapy.3, 4, 5, 6 Furthermore, as discussed above, previously reported CI rates associated with JAK inhibitor therapy might not be valid in the context of the 2013 revised criteria. In the current study, we provide a retrospective estimation of response, taking into consideration elements of the 2013 IWG-MRT-ELN criteria, wherever possible, for 111 patients with MF treated with either momelotinib (n=60) or ruxolitinib (n=51), in the context of phase-1/2 studies at our institution.5,7,8

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References

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Acknowledgements

Drugs and support for the conduct of the clinical trials were provided by Incyte Corporation, Wilmington, DE, USA (ruxolitinib) and YM BioSciences, Inc., Mississauga, Canada (momelotinib).

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Authors and Affiliations

  1. Division of Hematology and Department of Medicine, Mayo Clinic, Rochester, MN, USA

    R A Abdelrahman, K H Begna, A Al-Kali, W J Hogan, M R Litzow & A Tefferi

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  1. R A Abdelrahman
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  2. K H Begna
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  3. A Al-Kali
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  4. W J Hogan
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  5. M R Litzow
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  6. A Tefferi
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Correspondence to A Tefferi.

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Abdelrahman, R., Begna, K., Al-Kali, A. et al. Revised assessment of response and long-term discontinuation rates among 111 patients with myelofibrosis treated with momelotinib or ruxolitinib. Leukemia 29, 498–500 (2015). https://doi.org/10.1038/leu.2014.286

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