XL228

XL228 is a multi-targeted tyrosine kinase inhibitor with IC50s of 5, 3.1, 1.6, 6.1, 2 nM for Bcr-Abl, Aurora A, IGF-1R, Src and Lyn, respectively.

Signaling Pathways >> Protein Tyrosine Kinase/RTK >> Bcr-Abl

Signaling Pathways >> Protein Tyrosine Kinase/RTK >> IGF-1R

Signaling Pathways >> Protein Tyrosine Kinase/RTK >> Src

Research Areas >> Cancer

Aurora A:3.1 nM (IC50)

IGF-1R:1.6 nM (IC50)

XL228 shows a broad pattern of protein kinase inhibition, including the tyrosine kinases IGF1R, SRC, ABL, FGFR1‐3, and ALK and the serine/threonine kinases Aurora A and Aurora B. A panel of kinase inhibitors including XL228 is profiled against a series of cancer cell lines with known alterations in major signaling pathways. Approximately 30% of the lines demonstrate XL228 IC50 values of <100nM in viability assays, including many lines with characterized ALK or FGFR mutations or amplifications. XL228 eliminates the phosphorylation of Aurora A and B at concentrations above 10 nM. Short‐term treatment of HeLa cells leads to disruption of mitotic spindle formation, with the majority of mitotic cells exhibiting a unipolar spindle and disorganized chromosomes[2]. It displays low nanomolar biochemical activity against wild type Abl kinase (Ki=5 nM), as well as the T315I form of Abl resistant to imatinib and dasatinib (Ki=1.4 nM). XL228 inhibits phosphorylation of BCR-ABL and its substrate STAT5 in K562 cells in vitro with IC50s of 33 and 43 nM, respectively[3].

Single-dose pharmacodynamics studies demonstrate a potent effect of XL228 on BCR-ABL signaling in K562 xenograft tumors. Phosphorylation of BCR-ABL is decreased by 50% at XL228 plasma concentrations of 3.5 μM; a similar decrease in phospho-STAT5 occurred at 0.8 μM plasma concentration[3].

[1]. Cortes J, et al. Preliminary Clinical Activity in a Phase I Trial of the BCR-ABL/IGF- 1R/Aurora Kinase Inhibitor XL228 in Patients with Ph++ Leukemias with Either Failure to Multiple TKI Therapies or with T315I Mutation. Blood 2008 112:3232

[2]. Douglas O, et al. Abstract C192: Characterization of the target profile of XL228, a multi‐targeted protein kinase inhibitor in phase 1 clinical development. Mol Cancer Ther 2009;8(12 Suppl):C192.

[3]. Shah N, et al. Targeting Drug-Resistant CML and Ph+-ALL with the Spectrum Selective Protein Kinase Inhibitor XL228. Blood 2007 110:474;

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