Related Experiment Video
Updated: Dec 7, 2025
Spectrophotometric Screening for Potential Inhibitors of Cytosolic Glutathione S-Transferases
Published on: October 10, 2020
A facile and sensitive method of quantifying glutaminase binding to its inhibitor CB-839 in tissues
Yicheng Chen1, Yiqing Zhao1, David L Bajor2
1Department of Genetics and Genome Sciences, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA; Case Comprehensive Cancer Center, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA.
Abstract:
Many cancer types reprogram their metabolism to become addicted to glutamine. One of the critical enzymes in the utilization of glutamine in these cells is glutaminase. CB-839 (telaglenastat) is a drug that targets glutaminase that is currently being evaluated in many clinical trials for efficacy in various cancer types that are known to be driven by glutamine metabolism. Despite its use, there are limited assays available for testing the pharmacodynamic on-target effects of CB-839 on the limited, small-volume patient samples that are obtained in early-phase clinical trials. Thus, we developed an assay based on the cellular thermal shift assay technique using AlphaLISA technology to show that CB-839 specifically engages glutaminase in colon cancer cell lines in vitro and in minute quantities of mouse xenograft tumors. Notably, we show that this assay detects CB-839 binding to glutaminase in platelets of patients collected while receiving CB-839 on a clinical trial. This assay may be used to study the pharmacodynamic profile of CB-839 in very small tissue samples obtained from patients on a clinical trial and may be useful in future studies designed to screen other inhibitors of glutaminase.
Insights
A new assay accurately measures the effects of glutaminase inhibitor CB-839 (telaglenastat) in small patient samples. This method enables pharmacodynamic studies for cancer patients undergoing clinical trials.
Area of Science:
- Oncology
- Biochemistry
- Pharmacology
Background:
- Cancer cells often rely on glutamine metabolism for survival.
- Glutaminase is a key enzyme in glutamine utilization and a target for cancer drugs.
- CB-839 (telaglenastat) is an investigational glutaminase inhibitor used in clinical trials for various cancers.
Purpose of the Study:
- To develop a sensitive assay for measuring the pharmacodynamic effects of CB-839.
- To validate the assay using small patient-derived samples.
- To facilitate drug efficacy studies in early-phase clinical trials.
Main Methods:
- Development of a cellular thermal shift assay (CETSA) combined with AlphaLISA technology.
- In vitro testing in colon cancer cell lines.
- Analysis of xenograft tumors and patient-derived platelets.
Main Results:
- The developed assay specifically detects CB-839 engagement with glutaminase.
- Assay validation in colon cancer cell lines and mouse xenograft tumors.
- Successful detection of CB-839 binding to glutaminase in patient platelets from a clinical trial.
Conclusions:
- The novel AlphaLISA-based CETSA is effective for assessing CB-839's on-target effects in minimal sample volumes.
- This assay can be utilized for pharmacodynamic profiling in early-phase clinical trials.
- The assay holds potential for screening other glutaminase inhibitors.
