Abstract 91: FLT3 is a major driver of glucose consumption in squamous cell lung cancer
Authors: Ghezzi Chiara , Damoiseaux Robert , Clark Peter M. 
Published: July 2021

Squamous cell lung cancer (SqCLC) represents 30% of all cases of non-small cell lung cancer. Despite the prevalence of SqCLC, there are few molecularly targeted therapies for SqCLC patients. There is an urgent need for new approaches in this area. SqCLC cells consume elevated levels of glucose and are highly dependent on glucose consumption for their survival. Targeting glucose consumption may be a valuable therapeutic strategy in SqCLC but is challenged by the fact that glucose consumption is critical for vital organs. Our ability to selectively target glucose consumption in SqCLC is limited by an incomplete understanding of the shared and distinct mechanisms through which SqCLC and healthy cells drive glucose consumption.

We recently developed and validated a high-throughput glucose consumption assay that serves as a platform technology for identifying new proteins and pathways that drive glucose consumption in cancerous and healthy cells. In this project, we screened H520, SK-MES-1, and H596 SqCLC cell lines against 3555 bioactive small molecules including a library of kinase inhibitors and FDA-approved drugs, and measured glucose consumption 24 hours after drug treatment. We discovered and validated 62 compounds that decreased glucose consumption per cell by &gt;50% in at least one cell line. From this list, we searched for compounds that decreased glucose consumption in all three cell lines, by &gt;70% in at least one cell line, and with an EC50 value &lt;~1 µM; that have been used in mice and people; that have not been previously linked to glucose consumption; and that do not significantly decrease cell growth at the time point measured (24 hours post-treatment). This led us to further investigate Pacritinib, a small molecule kinase inhibitor in clinical trials for the treatment of myelofibrosis.

Pacritinib reduces glucose consumption in all three SqCLC cell lines with an EC50 value of 1.2 µM in cell culture and blocks glucose consumption in cell line xenografts in vivo without affecting glucose consumption in healthy tissues. In the SqCLC cell lines, Pacritinib decreases protein levels of Hexokinase 1 and Hexokinase 2 as well as hexokinase activity as measured by a FRET-based glucose sensor. Hexokinase 1 overexpression in the SqCLC cell lines blocks Pacritinib from inhibiting glucose consumption. Pacritinib targets JAK2, TYK2, FLT3, and additional kinases at low nanomolar concentrations in vitro. Additional small molecule inhibitors of JAK2 and TYK2 had no effect on SqCLC glucose consumption. However additional inhibitors of FLT3 blocked glucose consumption in all three SqCLC cell lines. FLT3 overexpression increased SqCLC glucose consumption and blocked Pacritinib from inhibiting glucose consumption.

In conclusion, using our high-throughput technology, we discovered that FLT3 is a selective and targetable driver of glucose consumption in SqCLC. Our data suggest that FLT3 activates glucose consumption by increasing Hexokinase 1 levels.

Citation Format: Chiara Ghezzi, Robert Damoiseaux, Peter M. Clark. FLT3 is a major driver of glucose consumption in squamous cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 91.