Efficacy of ALK5 inhibition in myelofibrosis
Lanzhu Yue, … , Amit Verma, Pearlie K. Epling-Burnette
Lanzhu Yue, … , Amit Verma, Pearlie K. Epling-Burnette
Published April 6, 2017
Citation Information: JCI Insight. 2017;2(7):e90932. https://doi.org/10.1172/jci.insight.90932.
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Research Article Hematology

Efficacy of ALK5 inhibition in myelofibrosis

Abstract

Myelofibrosis (MF) is a bone marrow disorder characterized by clonal myeloproliferation, aberrant cytokine production, extramedullary hematopoiesis, and bone marrow fibrosis. Although somatic mutations in JAK2, MPL, and CALR have been identified in the pathogenesis of these diseases, inhibitors of the Jak2 pathway have not demonstrated efficacy in ameliorating MF in patients. TGF-β family members are profibrotic cytokines and we observed significant TGF-β1 isoform overexpression in a large cohort of primary MF patient samples. Significant overexpression of TGF-β1 was also observed in murine clonal MPLW515L megakaryocytic cells. TGF-β1 stimulated the deposition of excessive collagen by mesenchymal stromal cells (MSCs) by activating the TGF-β receptor I kinase (ALK5)/Smad3 pathway. MSCs derived from MPLW515L mice demonstrated sustained overproduction of both collagen I and collagen III, effects that were abrogated by ALK5 inhibition in vitro and in vivo. Importantly, use of galunisertib, a clinically active ALK5 inhibitor, significantly improved MF in both MPLW515L and JAK2V617F mouse models. These data demonstrate the role of malignant hematopoietic stem cell (HSC)/TGF-β/MSC axis in the pathogenesis of MF, and provide a preclinical rationale for ALK5 blockade as a therapeutic strategy in MF.

Authors

Lanzhu Yue, Matthias Bartenstein, Wanke Zhao, Wanting Tina Ho, Ying Han, Cem Murdun, Adam W. Mailloux, Ling Zhang, Xuefeng Wang, Anjali Budhathoki, Kith Pradhan, Franck Rapaport, Huaquan Wang, Zonghong Shao, Xiubao Ren, Ulrich Steidl, Ross L. Levine, Zhizhuang Joe Zhao, Amit Verma, Pearlie K. Epling-Burnette

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Figure 5

Galunisertib in vivo treatment reverses the fibrotic phenotype of the MSCs in MPLW515L mice.

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Galunisertib in vivo treatment reverses the fibrotic phenotype of the MS...
(A) Diagram showing the procedures of the experiments. After randomization on either day 10 or day 12, groups of mice were treated for 14 days with of vehicle or galunisertib (Galu) in vivo. Mesenchymal stromal cells (MSCs) were then isolated from MPLW515L mice and cultured for collagen production analysis. (B–D) Representative images of MSCs from MPLWT (B) and MPLW515L mice treated with vehicle (C) or 300 mg/kg galunisertib (D) are shown. Original magnification, ×250. (E) Col1A1 and Col3A1 mRNA production was measured by qRT-PCR relative to TATA sequence–binding protein (TBP) in the MSCs (n = 6). **P < 0.01, ***P < 0.001 by ANOVA, followed by Dunnett’s multiple comparison test. (F) Signaling pathways in the MSCs were detected by Western blot after galunisertib in vivo treatment. See complete unedited blots in the supplemental material.