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A Method for Screening and Validation of Resistant Mutations Against Kinase Inhibitors
Published on: December 7, 2014
Tumors with AKT1E17K Mutations Are Rational Targets for Single Agent or Combination Therapy with AKT Inhibitors
Barry R Davies1, Nin Guan2, Armelle Logie3
1Oncology iMED, AstraZeneca, Alderley Park, Macclesfield, United Kingdom. barry.davies@astrazeneca.com.
Abstract:
AKT1(E17K) mutations occur at low frequency in a variety of solid tumors, including those of the breast and urinary bladder. Although this mutation has been shown to transform rodent cells in culture, it was found to be less oncogenic than PIK3CA mutations in breast epithelial cells. Moreover, the therapeutic potential of AKT inhibitors in human tumors with an endogenous AKT1(E17K) mutation is not known. Expression of exogenous copies of AKT1(E17K) in MCF10A breast epithelial cells increased phosphorylation of AKT and its substrates, induced colony formation in soft agar, and formation of lesions in the mammary fat pad of immunodeficient mice. These effects were inhibited by the allosteric and catalytic AKT inhibitors MK-2206 and AZD5363, respectively. Both AKT inhibitors caused highly significant growth inhibition of breast cancer explant models with AKT1(E17K) mutation. Furthermore, in a phase I clinical study, the catalytic Akt inhibitor AZD5363 induced partial responses in patients with breast and ovarian cancer with tumors containing AKT1(E17K) mutations. In MGH-U3 bladder cancer xenografts, which contain both AKT1(E17K) and FGFR3(Y373C) mutations, AZD5363 monotherapy did not significantly reduce tumor growth, but tumor regression was observed in combination with the FGFR inhibitor AZD4547. The data show that tumors with AKT1(E17K) mutations are rational therapeutic targets for AKT inhibitors, although combinations with other targeted agents may be required where activating oncogenic mutations of other proteins are present in the same tumor.
Insights
The AKT1(E17K) mutation drives tumor growth and is a target for AKT inhibitors. Clinical studies show these inhibitors can be effective, sometimes requiring combination therapy for optimal results in certain cancers.
Area of Science:
- Oncology
- Molecular Biology
- Cancer Therapeutics
Background:
- Activating mutations in AKT1, specifically AKT1(E17K), are found in various solid tumors.
- While AKT1(E17K) transforms rodent cells, its oncogenic potential and therapeutic targeting in human cancers remain under investigation.
- The efficacy of AKT inhibitors in human tumors harboring endogenous AKT1(E17K) mutations is not well-established.
Purpose of the Study:
- To investigate the oncogenic role of AKT1(E17K) in breast epithelial cells.
- To evaluate the therapeutic efficacy of AKT inhibitors against tumors with AKT1(E17K) mutations.
- To explore the potential of combination therapies for tumors with co-occurring mutations.
Main Methods:
- Exogenous expression of AKT1(E17K) in MCF10A cells to assess cellular transformation and in vivo tumor formation.
- Treatment of breast cancer explants and MGH-U3 bladder cancer xenografts with AKT inhibitors (MK-2206, AZD5363) and/or FGFR inhibitor (AZD4547).
- Analysis of a Phase I clinical study involving AZD5363 in cancer patients with AKT1(E17K) mutations.
Main Results:
- Expression of AKT1(E17K) increased AKT phosphorylation, colony formation, and tumor growth in mice, effects reversed by AKT inhibitors.
- Both allosteric and catalytic AKT inhibitors significantly inhibited growth in breast cancer models with AKT1(E17K).
- Phase I study showed partial responses to AZD5363 in patients with AKT1(E17K)-mutated breast and ovarian cancers. AZD5363 combined with AZD4547 showed tumor regression in bladder cancer xenografts with AKT1(E17K) and FGFR3(Y373C) mutations.
Conclusions:
- Tumors harboring the AKT1(E17K) mutation represent a validated therapeutic target for AKT inhibitors.
- AKT inhibitors demonstrate clinical activity in patients with AKT1(E17K)-mutated cancers.
- Combination therapy with other targeted agents may be necessary for tumors with multiple oncogenic driver mutations, such as AKT1(E17K) and FGFR3(Y373C).
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