An allosteric Akt inhibitor effectively blocks Akt signaling and tumor growth with only transient effects on glucose and insulin levels in vivo

Craig Cherrin, Kathleen Haskell, Bonnie Howell, Raymond Jones, Karen Leander, Ronald Robinson, Aubrey Watkins, Mark Bilodeau, Jacob Hoffman, Philip Sanderson, George Hartman, Elizabeth Mahan, Thomayant Prueksaritanont, Guoqiang Jiang, Qing Bai She, Neal Rosen, Laura Sepp-Lorenzino, Deborah Defeo-Jones, Hans E. Huber

Research output: Contribution to journalArticlepeer-review

57 Scopus citations

Abstract

The PI3K-Akt pathway is dysregulated in the majority of solid tumors. Pharmacological inhibition of Akt is a promising strategy for treating tumors resistant to growth factor receptor antagonists due to mutations in PI3K or PTEN. We have developed allosteric, isozyme-specific inhibitors of Akt activity and activation, as well as ex vivo kinase assays to measure inhibition of individual Akt isozymes in tissues. Here we describe the relationship between PK, Akt inhibition, hyperglycemia and tumor efficacy for a selective inhibitor of Akt1 and Akt2 (AKTi). In nude mice, AKTi treatment caused transient insulin resistance and reversible, dose-dependent hyperglycemia and hyperinsulinemia. Akt1 and Akt2 phosphorylation was inhibited in mouse lung with EC50 values of 1.6 and 7 μM, respectively, and with similar potency in other tissues and xenograft tumors. Weekly subcutaneous dosing of AKTi resulted in dose-dependent inhibition of LNCap prostate cancer xenografts, an AR-dependent tumor with PTEN deletion and constitutively activated Akt. Complete tumor growth inhibition was achieved at 200 mpk, a dose that maintained inhibition of Akt1 and Akt2 of greater than 80 and 50%, respectively, for at least 12 h in xenograft tumor and mouse lung. Hyperglycemia could be controlled by reducing Cmax, while maintaining effi cacy in the LNCap model, but not by insulin administration. AKTi treatment was well tolerated, without weight loss or gross toxicities. These studies supported the rationale for clinical development of allosteric Akt inhibitors and provide the basis for further refining of pharmacokinetic properties and dosing regimens of this class of inhibitors.

Original languageEnglish
Pages (from-to)493-503
Number of pages11
JournalCancer Biology and Therapy
Volume9
Issue number7
DOIs
StatePublished - Apr 1 2010

Keywords

  • Akt
  • Hyperglycemia
  • Inhibitor
  • Isozyme-specific
  • Pharmacodynamics

ASJC Scopus subject areas

  • Molecular Medicine
  • Oncology
  • Pharmacology
  • Cancer Research

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