Glutamine utilization in patient-derived breast cancer xenografts under treatment with the glutaminase inhibitor CB-839
In recent years, there has been great interest in the abnormal metabolism observed in cancer, resulting in development of novel anticancer drugs targeting metabolic reactions. Among these drugs is the glutaminase inhibitor CB-839, which currently is in early-phase clinical trials in breast cancer (clinicaltrials.gov identifier: NCT02071862).
However, the drug is not effective in all patients, due to metabolic heterogeneity and different degree of glutamine addiction in different tumors. More knowledge about metabolic plasticity and redundancy, causingresistance to glutaminase inhibition, is needed for improved prediction of outcome and, ultimately, stratification of patients to therapy with CB-839.
In a recent experiment (FOTS ID 7713), we demonstrated that CB-839 significantly inhibited tumor growth in a luminal-like breast cancer xenograft model (MAS98.06), whereas no response was seen in a basal-like xenograft tumor model (MAS98.12).
Our hypothesis is that differences in glutamine utilization between these two models accounts for the differential response.
The objective of the current experiment is therefore to compare the glutamine consumption in responding and non-responding breast xenografts prior to therapy, and to compare the metabolic response following CB-839 treatment.
We will perform an in vivo glutamine tracing experiment, where mice carrying MAS98.12 or MAS98.06 xenografts will receive an infusion with 13C-enriched glutamine. Following termination of the mice, tumor tissue will be harvested and 13C NMR analysis will be performed to explore the metabolic fate of glutamine in the tumors.
We will use a total of 32 xenograft-bearing BalbC nu/nu mice:
8 x MAS98.06, no therapy
8 x MAS98.12, no therapy
8 x MAS98.06, treated with CB-839 for 2 days
8 x MAS98.12, treated with CB-839 for 2 days
To ensure that the experimental protocol can be carried out successfully in all mice, we have also applied for up to 20 non-tumor bearing mice to practice the infusion procedure and verify that it does not cause significant inconvenience to the mice.
The experiment is designed to compare differences in metabolic characteristics, specifically glutamine consumption and utilization, in responding and non-responding tumors. If successful, the study will provide valuable information that can guide design of future clinical trials of CB-839 in breast cancer patients.
The experiment must be carried out in a preclinical model, because the microenvironment of solid tumors significantly regulates metabolic activity and influence the efficacy of anticancer treatment (including metabolic inhibitors). We will use patient-derived xenograft models, as these represent the heterogeneity of human disease, and have higher translational value than traditional models.
The number of mice to be used in the study is based on extensive experience with these animal models, and NMR studies of metabolic properties in solid tumors. The explorative nature of the experiment does not allow us to perform formal power calculations.
The infusion procedure has been developed by a collaborating research group in the UK, and has been successfully performed in awake, restrained mice. We have, however, chosen to perform glutamine infusions in anaesthetized (isoflurane) mice to reduce stress and inconvenience.
However, the drug is not effective in all patients, due to metabolic heterogeneity and different degree of glutamine addiction in different tumors. More knowledge about metabolic plasticity and redundancy, causingresistance to glutaminase inhibition, is needed for improved prediction of outcome and, ultimately, stratification of patients to therapy with CB-839.
In a recent experiment (FOTS ID 7713), we demonstrated that CB-839 significantly inhibited tumor growth in a luminal-like breast cancer xenograft model (MAS98.06), whereas no response was seen in a basal-like xenograft tumor model (MAS98.12).
Our hypothesis is that differences in glutamine utilization between these two models accounts for the differential response.
The objective of the current experiment is therefore to compare the glutamine consumption in responding and non-responding breast xenografts prior to therapy, and to compare the metabolic response following CB-839 treatment.
We will perform an in vivo glutamine tracing experiment, where mice carrying MAS98.12 or MAS98.06 xenografts will receive an infusion with 13C-enriched glutamine. Following termination of the mice, tumor tissue will be harvested and 13C NMR analysis will be performed to explore the metabolic fate of glutamine in the tumors.
We will use a total of 32 xenograft-bearing BalbC nu/nu mice:
8 x MAS98.06, no therapy
8 x MAS98.12, no therapy
8 x MAS98.06, treated with CB-839 for 2 days
8 x MAS98.12, treated with CB-839 for 2 days
To ensure that the experimental protocol can be carried out successfully in all mice, we have also applied for up to 20 non-tumor bearing mice to practice the infusion procedure and verify that it does not cause significant inconvenience to the mice.
The experiment is designed to compare differences in metabolic characteristics, specifically glutamine consumption and utilization, in responding and non-responding tumors. If successful, the study will provide valuable information that can guide design of future clinical trials of CB-839 in breast cancer patients.
The experiment must be carried out in a preclinical model, because the microenvironment of solid tumors significantly regulates metabolic activity and influence the efficacy of anticancer treatment (including metabolic inhibitors). We will use patient-derived xenograft models, as these represent the heterogeneity of human disease, and have higher translational value than traditional models.
The number of mice to be used in the study is based on extensive experience with these animal models, and NMR studies of metabolic properties in solid tumors. The explorative nature of the experiment does not allow us to perform formal power calculations.
The infusion procedure has been developed by a collaborating research group in the UK, and has been successfully performed in awake, restrained mice. We have, however, chosen to perform glutamine infusions in anaesthetized (isoflurane) mice to reduce stress and inconvenience.