Molecular rationale for the use of PI3K/AKT/mTOR pathway inhibitors in combination with crizotinib in ALK-mutated neuroblastoma
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Nathan F. Moore1,*, Anna M. Azarova1,*, Namrata Bhatnagar1, Kenneth N. Ross4, Lauren E. Drake1, Stacey Frumm1, Qinsong S. Liu2,5, Amanda L. Christie3, Takaomi Sanda1,7, Louis Chesler6, Andrew L. Kung1,3, Nathanael S. Gray2,5, Kimberly Stegmaier1,4 and Rani E. George1
1 Departments of Pediatric Hematology/Oncology, Dana-Farber Cancer Institute, Boston, MA
2 Cancer Biology, Dana-Farber Cancer Institute, Boston, MA
3 Lurie Family Imaging Center, Dana-Farber Cancer Institute, Boston, MA
4 Broad Institute of MIT and Harvard, Cambridge, MA
5 Departments of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA
6 Institute of Cancer Research, Sutton, United Kingdom
7 Cancer Science Institute of Singapore, Singapore
* These authors contributed equally to this work
Rani E. George, email:
Keywords: ALK, neuroblastoma, crizotinib, mTOR inhibitor, MYCN
Received: July 28, 2014 Accepted: August 18, 2014 Published: August 19, 2014
Mutations in the ALK tyrosine kinase receptor gene represent important therapeutic targets in neuroblastoma, yet their clinical translation has been challenging. The ALKF1174L mutation is sensitive to the ALK inhibitor crizotinib only at high doses and mediates acquired resistance to crizotinib in ALK-translocated cancers. We have shown that the combination of crizotinib and an inhibitor of downstream signaling induces a favorable response in transgenic mice bearing ALKF1174L/MYCN-positive neuroblastoma. Here, we investigated the molecular basis of this effect and assessed whether a similar strategy would be effective in ALK-mutated tumors lacking MYCN overexpression. We show that in ALK-mutated, MYCN-amplified neuroblastoma cells, crizotinib alone does not affect mTORC1 activity as indicated by persistent RPS6 phosphorylation. Combined treatment with crizotinib and an ATP-competitive mTOR inhibitor abrogated RPS6 phosphorylation, leading to reduced tumor growth and prolonged survival in ALKF1174L/MYCN-positive models compared to single agent treatment. By contrast, this combination, while inducing mTORC1 downregulation, caused reciprocal upregulation of PI3K activity in ALK-mutated cells expressing wild-type MYCN. Here, an inhibitor with potency against both mTOR and PI3K was more effective in promoting cytotoxicity when combined with crizotinib. Our findings should enable a more precise selection of molecularly targeted agents for patients with ALK-mutated tumors.
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