1.INCB16562, a JAK1/2 selective inhibitor, is efficacious against multiple myeloma cells and reverses the protective effects of cytokine and stromal cell support.
Li J1, Favata M, Kelley JA, Caulder E, Thomas B, Wen X, Sparks RB, Arvanitis A, Rogers JD, Combs AP, Vaddi K, Solomon KA, Scherle PA, Newton R, Fridman JS. Neoplasia. 2010 Jan;12(1):28-38.
Cytokines in the bone marrow of multiple myeloma patients activate Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling pathways in tumor cells and promote tumor growth, survival, and drug resistance. INCB16562 was developed as a novel, selective, and orally bioavailable small-molecule inhibitor of JAK1 and JAK2 markedly selective over JAK3. The specific cellular activity of the inhibitor was demonstrated by its potent and dose-dependent inhibition of cytokine-dependent JAK/STAT signaling and cell proliferation in the absence of effects on Bcr-Abl-expressing cells. Treatment of myeloma cells with INCB16562 potently inhibited interleukin-6 (IL-6)-induced phosphorylation of STAT3. Moreover, the proliferation and survival of myeloma cells dependent on IL-6 for growth, as well as the IL-6-induced growth of primary bone marrow-derived plasma cells from a multiple myeloma patient, were inhibited by INCB16562. Induction of caspase activation and apoptosis was observed and attributed, at least in part, to the suppression of Mcl-1 expression.
2.Efficacy of the JAK2 inhibitor INCB16562 in a murine model of MPLW515L-induced thrombocytosis and myelofibrosis.
Koppikar P1, Abdel-Wahab O, Hedvat C, Marubayashi S, Patel J, Goel A, Kucine N, Gardner JR, Combs AP, Vaddi K, Haley PJ, Burn TC, Rupar M, Bromberg JF, Heaney ML, de Stanchina E, Fridman JS, Levine RL. Blood. 2010 Apr 8;115(14):2919-27. doi: 10.1182/blood-2009-04-218842. Epub 2010 Feb 12.
The discovery of JAK2 and MPL mutations in patients with myeloproliferative neoplasms (MPNs) provided important insight into the genetic basis of these disorders and led to the development of JAK2 kinase inhibitors for MPN therapy. Although recent studies have shown that JAK2 kinase inhibitors demonstrate efficacy in a JAK2V617F murine bone marrow transplantation model, the effects of JAK2 inhibitors on MPLW515L-mediated myeloproliferation have not been investigated. In this report, we describe the in vitro and in vivo effects of INCB16562, a small-molecule JAK2 inhibitor. INCB16562 inhibited proliferation and signaling in cell lines transformed by JAK2 and MPL mutations. Compared with vehicle treatment, INCB16562 treatment improved survival, normalized white blood cell counts and platelet counts, and markedly reduced extramedullary hematopoeisis and bone marrow fibrosis. We observed inhibition of STAT3 and STAT5 phosphorylation in vivo consistent with potent inhibition of JAK-STAT signaling.
3.Combined inhibition of Janus kinase 1/2 for the treatment of JAK2V617F-driven neoplasms: selective effects on mutant cells and improvements in measures of disease severity.
Liu PC1, Caulder E, Li J, Waeltz P, Margulis A, Wynn R, Becker-Pasha M, Li Y, Crowgey E, Hollis G, Haley P, Sparks RB, Combs AP, Rodgers JD, Burn TC, Vaddi K, Fridman JS. Clin Cancer Res. 2009 Nov 15;15(22):6891-900. doi: 10.1158/1078-0432.CCR-09-1298. Epub 2009 Nov 3.
PURPOSE: Deregulation of the Janus kinase-signal transducers and activators of transcription (JAK-STAT) pathway is a hallmark for the Philadelphia chromosome-negative myeloproliferative diseases polycythemia vera, essential thrombocythemia, and primary myelofibrosis. We tested the efficacy of a selective JAK1/2 inhibitor in cellular and in vivo models of JAK2-driven malignancy.