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Research Area
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Description
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Mantle cell lymphoma ,Chronic lymphocytic leukaemia |
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Biological Activity
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Description
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PCI-32765 (Ibrutinib) is a potent and highly selective Btk inhibitor with IC50 of 0.5 nM. |
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Targets
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Btk |
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IC50 |
0.5 nM [1] |
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In Vitro
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PCI-32765 shows the potent and irreversible inhibitory effect and selectivity for Btk enzymatic activity. In BCR pathway-activated DOHH2 cell line, PCI-32765 inhibits autophosphorylation of Btk, phosphorylation of Btk's physiological substrate PLCγ, and phosphorylation of further downstream kinase, ERK with IC50 of 11 nM, 29 nM and 13 nM, respectively. [1] PCI-32765 exhibits a significant dose-dependent and time-dependent induction of cytotoxicity in chronic lymphocytic leukemia (CLL) cells. In addition, PCI-32765 induces cell death depending on caspase pathway activation and antagonizes the ability of CLL cells to proliferate after TLR signaling. [2] A recent study shows that PCI-32765 inhibits BCR-activated primary B cell proliferation with IC50 of 8 nM and results in inhibition of TNFα, IL-1β and IL-6 production in primary monocytes with IC50 of 2.6 nM, 0.5 nM and 3.9 nM, respectively. [3] |
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In Vivo
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In a collagen-induced arthritis model, PCI-32765 significantly reduces clinical arthritis scores reflecting paw swelling and joint inflammation by inhibiting B-cell activation. In a MRL-Fas(lpr) lupus model, PCI-32765 reduces renal disease and autoantibody production. [1] In an adoptive transfer TCL1 mouse model of CLL, PCI-32765 (25 mg/kg/day) causes a transient early lymphocytosis, and delays CLL disease progression. [4] |
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Clinical Trials
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PCI-32765 is currently in Phase II clinical trials in patients with Chronic Lymphocytic Leukemia (CLL) or Small Lymphocytic Lymphoma (SLL). Combination of PCI-32765 and Rituximab is currently in Phase II clinical trials in patients with High-Risk Chronic Lymphocytic Leukemia (CLL) and Small Lymphocytic Lymphoma (SLL). |
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Features
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Combination Therapy
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Description
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The use of PCI-32765 in combination with Bendamustine and Rituximab is currently in Phase III clinical trials in patients with Chronic Lymphocytic Leukemia and Small Lymphocytic Lymphoma. |
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Protocol
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Kinase Assay
[1]
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| Kinase Assays |
In vitro kinase IC50 values are measured using 33P filtration binding assay after 1 hour incubation of kinase, 33P-ATP, PCI-32765, and substrate [0.2 mg/mL poly(EY)(4:1]. Assays are performed at Reaction Biology. |
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Cell Assay
[2]
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| Cell Lines |
Chronic lymphocytic leukemia (CLL) cells |
| Concentrations |
0.01-100 μM |
| Incubation Time |
48 hours |
| Methods |
MTT (3'[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide) assays are performed to determine cytotoxicity. Briefly, cells (CLL B cells or healthy volunteer T cells or NK cells) are incubated for 48 hours with different concentrations of PCI-32765, or vehicle control. MTT reagent is then added, and plates are incubated for an additional 20 hours before washing with protamine sulfate in phosphate-buffered saline. Dimethyl sulfoxide is added, and absorbance is measured by spectrophotometry at 540 nm in a Labsystems plate reader. Cell viability is also measured at various time points with the use of annexin/PI flow cytometry. Data are analyzed with Expo-ADC32 software package. Results are expressed as the percentage of total positive cells over untreated control. Experiments examining caspase-dependent apoptosis includes the addition of 100μM Z-VAD. |
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Animal Study
[1]
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| Animal Models |
MRL-Fas(lpr) lupus model and collagen-induced arthritis model. |
| Formulation |
PCI-32765 is dissolved in DMSO. |
| Doses |
≤50 mg/kg |
| Administration |
Administered via p.o. |
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References |
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[1] Honigberg LA, et al. Proc Natl Acad Sci U S A. 2010, 107(29), 13075-13080.
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[2] Herman SE, et al. Blood. 2011, 117(23), 6287-6296.
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[3] Chang BY, et al. Arthritis Res Ther. 2011, 13(4), R115.
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[4] Ponader S, et al. Blood. 2012, 119(5), 1182-1189.
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