Pacritinib (SB1518)
Catalog No.S8057
Molecular Weight(MW): 472.58
Pacritinib (SB1518) is a potent and selective inhibitor of Janus Kinase 2 (JAK2) and Fms-Like Tyrosine Kinase-3 (FLT3) with IC50s of 23 and 22 nM in cell-free assays, respectively. Phase 3.
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Biological Activity
| Description | Pacritinib (SB1518) is a potent and selective inhibitor of Janus Kinase 2 (JAK2) and Fms-Like Tyrosine Kinase-3 (FLT3) with IC50s of 23 and 22 nM in cell-free assays, respectively. Phase 3. | |||||||||||
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| Features | Dual JAK2/FLT3 inhibitor that has progressed to Phase III clinical trials for treatment of Myelofibrosis. | |||||||||||
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| In vitro |
Pacritinib is a potent inhibitor of both wild-type JAK2 and JAK2V617F mutant (IC50= 19 nM) that is present in high frequencies among patients with MPD. Relative to JAK2, Pacritinib is two-fold less potent against TYK2 (IC50= 50 nM), 23-fold less potent against JAK3 (IC50= 520 nM) and 56-fold less potent against JAK1 (IC50= 1280 nM). Pacritinib effectively permeates cells to modulate signaling pathways downstream of JAK2, whether agonist activated or mutationally activated. Pacritinib induces apoptosis, cell cycle arrest and antiproliferative effects in JAK2WT- and JAK2V617F-dependent cells. Pacritinib inhibits cell proliferation of Karpas 1106P and Ba/F3-JAK2V617F with IC50 of 348 and 160 nM, respectively. Pacritinib inhibits endogenous colony growth derived from erythroid and myeloid progenitors with IC50 of 63 and 53 nM , respectively. [1] SB1518 also inhibits FLT3 and its mutant FLT3-D835Y(IC50= 6 nM ). Pacritinib inhibits FLT3 phosphorylation and downstream STAT, MAPK and PI3K signaling in FLT3-internal-tandem duplication (ITD), FLT3-wt cells and primary AML blast cells. Pacritinib treatment leads to a dose-dependent decrease of pFLT3, pSTAT5, pERK1/2 and pAkt in FLT3-ITD harboring MV4-11 cells with IC50 of 80, 40, 33 and 29 nM , respectively. Treatment of the primary AML blast cells with Pacritinib for 3 h leads to a dose-dependent decrease of pFLT3, pSTAT3 and pSTAT5 with an IC50 below 0.5 μM. Pacritinib induces apoptosis, cell cycle arrest and anti-proliferative effects in FLT3-mutant and FLT3-wt cells. Pacritinib inhibits cell proliferation of FLT3-ITD-harboring cells MV4-11 and primary AML blast cells with IC50s of 47 nM and 0.19-1.3 μM, respectively. [2] |
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| In vivo | Pacritinib administrated at 150 mg/kg p.o. q.d. to JAK2V617F-dependent xenograft model, significantly ameliorates splenomegaly and hepatomegaly symptoms, with 60% normalization of spleen weight and 92% normalization of liver weight and is well tolerated without significant weight loss or any hematological toxicities, including thrombocytopenia and anemia. Pacritinib induces dose-dependent inhibition of tumor growth of JAK2V617F-dependent SET-2 xenograft model (40% for 75 mg/kg and 61% for 150 mg/kg). [1] Pacritinib is efficacious in FLT3-ITD-bearing MV4-11 xenograft models. Pacritinib treated once daily for 21 consecutive days, induces dose-dependent inhibition of tumor growth (38% for 25 mg/kg, 92% for 50 mg/kg and 121% for 100 mg/kg). Complete regression is observed in 3/10 and 8/8 mice for the 50 and 100 mg/kg/day groups, respectively. [2] |
Protocol
| Kinase Assay:[1] |
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kinase activity assays: All assays are carried out in 384-well white microtiter plates. Compounds are 4-fold serially diluted in 8 steps, starting from 10 μM. The reaction mixture consisted of 25 μL assay buffer (50 mM HEPES pH 7.5, 10 mM MgCl2, 5 mM MnCl2, 1 mM DTT, 0.1 mM Na3VO4, 5 mM β-glycerol phosphate). For FLT3 assays, the reaction contains 2.0 μg/mL FLT3 enzyme, 5 μM of poly(Glu,Tyr) substrate and 4 μM of ATP. For JAK1 assays, the reaction contains 2.5 μg/mL of JAK1 enzyme, 10 μM of poly(Glu,Ala,Tyr) substrate and 1.0 μM of ATP. For JAK2 assays, the reaction contained 0.35 μg/mL of JAK2 enzyme, 10 μM of poly (Glu,Ala,Tyr) substrate and 0.15 μM of ATP. For JAK3 assays, the reaction contained 3.5 μg/mL of JAK3 enzyme, 10 μM of poly (Glu,Ala,Tyr) substrate and 6.0 μM of ATP. For TYK2 assays, the reaction contained 2.5 μg/mL of TYK2 enzyme, 10 μM of poly (Glu,Ala,Tyr) substrate and 0.15 μM of ATP. The reaction is incubated at room temperature for 2 h prior to addition of 13 μL PKLight® detection reagent. After 10 min incubation luminescent signals are read on a multi-label plate reader. |
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| Cell Research:[1] |
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| Animal Research:[1] |
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Solubility (25°C)
| In vitro | DMSO | 11 mg/mL warmed (23.27 mM) |
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| Water | Insoluble | |
| Ethanol | Insoluble |
* Please note that Selleck tests the solubility of all compounds in-house, and the actual solubility may differ slightly from published values. This is normal and is due to slight batch-to-batch variations.
Chemical Information
| Molecular Weight | 472.58 |
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| Formula | C28H32N4O3 |
| CAS No. | 937272-79-2 |
| Storage | powder |
| in solvent | |
| Synonyms | N/A |
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Clinical Trial Information
| NCT Number | Recruitment | Conditions | Sponsor/Collaborators | Start Date | Phases |
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| NCT03601819 | Not yet recruiting | Lymphoma T-Cell Cutaneous|Lymphoma T-Cell Peripheral|Chronic Lymphocytic Leukemia|Lymphoproliferative Disorders|Waldenstrom Macroglobulinemia|Lymphoplasmacytic Lymphoma|Mantle Cell Lymphoma | University of Michigan Rogel Cancer Center | March 2019 | Phase 1 |
| NCT03601819 | Not yet recruiting | Lymphoma T-Cell Cutaneous|Lymphoma T-Cell Peripheral|Chronic Lymphocytic Leukemia|Lymphoproliferative Disorders|Waldenstrom Macroglobulinemia|Lymphoplasmacytic Lymphoma|Mantle Cell Lymphoma | University of Michigan Rogel Cancer Center | March 2019 | Phase 1 |
| NCT03645824 | Recruiting | Myelofibrosis | Stichting Hemato-Oncologie voor Volwassenen Nederland|Dutch Cancer Society|CTI BioPharma | June 4 2018 | Phase 2 |
| NCT03645824 | Recruiting | Myelofibrosis | Stichting Hemato-Oncologie voor Volwassenen Nederland|Dutch Cancer Society|CTI BioPharma | June 4 2018 | Phase 2 |
| NCT03165734 | Active not recruiting | Primary Myelofibrosis|Post-polycythemia Vera Myelofibrosis|Post-essential Thrombocythemia Myelofibrosis | CTI BioPharma|Covance | June 26 2017 | Phase 2 |
| NCT02564536 | Withdrawn | Chronic Myelomonocytic Leukemia|Juvenile Myelomonocytic Leukemia|Atypical Chronic Myeloid Leukemia|Myeloproliferative Neoplasm|Myelodysplastic Syndromes|Myelofibrosis | Washington University School of Medicine|CTI BioPharma | June 2017 | Phase 1 |
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