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A.A. Cortés et al.
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Figure 4. Effect of ruxolitinib (R), nilotinib (N), prednisone (P), and their combination, on collagen I mRNA expression using quantita- tive polymerase chain reaction or protein expression by immunocy- tochemistry. HS27a cell line was incubated with R, N, P or their com- bination for 1 hour (h) and then for 24 h with 2 ng/mL TGF-β. Results
were expressed as mean±Standard Error of Mean. Data are representative of at least 2 independent experiments. *P<0.05; **P<0.01.
the
the need to increase the effectiveness of the treatment and decrease its toxicity.
We found that the best combinations were those with BCR/ABL inhibitors, nilotinib and bosutinib, used for the treatment of chronic myeloid leukemia (CML).31 Nevertheless, TKIs such as perifosine or BKM120, corticos- teroids such as prednisone, androgens such as danazol, and the TGF-β receptor inhibitor SB431542, also decreased the EC50 in combination with ruxolitinib. It is interesting to note that some of these combinations have already been tested in clinical trials, such as ruxolitinib plus danazol (clin- icaltrials.gov identifier: 01732445);18 this study showed that while there was no improvement in hematologic response, stabilization of the patients was achieved. Regarding ruxolitinib plus BKM120 (clinicaltrials.gov identifi- er: 01730248), although no results have yet been reported, preliminary analyses (ASH 2015) are not encouraging.
Interestingly, it has previously been described that the combination nilotinib plus ruxolitinib can eliminate CD34+ leukemic progenitors in CML32 and Philadelphia chromo-
some positive acute lymphoblastic leukemia;33 however, it was not known whether this also holds for MF. We show here synergistic behavior of nilotinib plus ruxolitinib, which blocks colony formation in clonogenic assays with patients' PMBCs, and inhibits the phosphorylation of both STAT5 and ERK 1/2. Furthermore, the inclusion of pred- nisone is key to achieve synergy in the survival assays of cell lines and increases the power of synergy in patients' samples. In addition, this combination inhibited the syn- thesis of collagen in BM mesenchymal cells, which is important to achieve histopathological response. The antifibrogenic effect of nilotinib has been previously described in skin cells,20,34 liver35 and muscle,36 via its ability to inhibit the PDGF receptor, which is directly involved in the induction of collagen synthesis. In addition, ruxolitinib is able to stabilize, or even ameliorate, fibrosis through its ability to reduce the proinflamatory state, which is typical in MF.37 Similar results are seen with corticosteroids like prednisone, which decreases the levels of cytokines and proinflammatory growth factors including TGF-β.24
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haematologica | 2019; 104(5)