A retrospective survival analysis of Glioblastoma patients treated with selective serotonin reuptake inhibitors

Glioblastoma (GBM) is the most common and aggressive form of malignant glioma in adults with a median overall survival (OS) time of 16–18 months and a median age of diagnosis at 64 years old. Recent work has suggested that depression and psychosocial distress are associated with worse outcomes in patients with GBM. We therefore hypothesized that the targeted neutralization of psychosocial distress with selective serotonin reuptake inhibitor (SSRI) antidepressant treatment would be associated with a longer OS among patients with GBM. To address this hypothesis, we retrospectively studied the association between adjuvant SSRI usage and OS in GBM patients treated by Northwestern Medicine-affiliated providers. The medical records of 497 GBM patients were analyzed after extraction from the Northwestern Medicine Enterprise Data Warehouse. Data were retrospectively studied using a multivariable Cox model with SSRI use defined as a time-dependent variable for estimating the association with OS. Of the 497 patients, 315 individuals died, while 182 were censored due to the loss of follow-up or were alive at the end of our study. Of the 497 patients, 151 had a recorded use of SSRI treatment during the disease course. Unexpectedly, SSRI usage was not associated with an OS effect in both naïve (HR ​= ​0.81, 95% CI ​= ​0.64–1.03) and adjusted time-dependent (HR ​= ​1.26, 95% CI ​= ​0.97–1.63) Cox models. Ultimately, we failed to find an association between SSRI treatment and an improved OS of patients with GBM. Additional work is necessary for understanding the potential therapeutic effects of SSRIs when combined with other treatment approaches, and immunotherapies in particular, for subjects with GBM.

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SSRI use was not associated with improved overall survival in GBM patients.

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Analysis included fluoxetine, citalopram, escitalopram, sertraline, paroxetine, vilazodone.

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Multiple statistical models were used to verify the findings.

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Time-dependent modeling of SSRI use was critical to avoid immortal time bias.

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Future work in animal models or prospective studies is critical.

Gain of glucose-independent growth upon metastasis of breast cancer cells to the brain

Breast cancer brain metastasis is resistant to therapy and a particularly poor prognostic feature in patient survival. Altered metabolism is a common feature of cancer cells, but little is known as to what metabolic changes benefit breast cancer brain metastases. We found that brain metastatic breast cancer cells evolved the ability to survive and proliferate independent of glucose due to enhanced gluconeogenesis and oxidations of glutamine and branched chain amino acids, which together sustain the nonoxidative pentose pathway for purine synthesis. Silencing expression of fructose-1,6-bisphosphatases (FBP) in brain metastatic cells reduced their viability and improved the survival of metastasis-bearing immunocompetent hosts. Clinically, we showed that brain metastases from human breast cancer patients expressed higher levels of FBP and glycogen than the corresponding primary tumors. Together, our findings identify a critical metabolic condition required to sustain brain metastasis and suggest that targeting gluconeogenesis may help eradicate this deadly feature in advanced breast cancer patients.

EGFR-SGLT1 interaction does not respond to EGFR modulators, but inhibition of SGLT1 sensitizes prostate cancer cells to EGFR tyrosine kinase inhibitors

BACKGROUND

Overexpression of epidermal growth factor receptor (EGFR) is associated with poor prognosis in malignant tumors. Sodium/glucose co-transporter 1 (SGLT1) is an active glucose transporter that is overexpressed in many cancers including prostate cancer. Previously, we found that EGFR interacts with and stabilizes SGLT1 in cancer cells.

METHODS

In this study, we determined the micro-domain of EGFR that is required for its interaction with SGLT1 and the effects of activation/inactivation of EGFR on EGFR-SGLT1 interaction, measured the expression of EGFR and SGLT1 in prostate cancer tissues, and tested the effect of inhibition of SGLT1 on the sensitivity of prostate cancer cells to EGFR tyrosine inhibitors.

RESULTS

We found that the autophosphorylation region (978-1210 amino acids) of EGFR was required for its sufficient interaction with SGLT1 and that this interaction was independent of EGFR's tyrosine kinase activity. Most importantly, the EGFR-SGLT1 interaction does not respond to EGFR tyrosine kinase modulators (EGF and tyrosine kinase inhibitors). EGFR and SGLT1 co-localized in prostate cancer tissues, and inhibition of SGLT1 by a SGLT1 inhibitor (Phlorizin) sensitized prostate cancer cells to EGFR inhibitors (Gefitinib and Erlotinib).

CONCLUSION

These data suggest that EGFR in cancer cells can exist as either a tyrosine kinase modulator responsive status or an irresponsive status. SGLT1 is a protein involved in EGFR's functions that are irresponsive to EGFR tyrosine kinase inhibitors and, therefore, the EGFR-SGLT1 interaction might be a novel target for prostate cancer therapy.

Abstract 993: Enhanced EGFR activity of prostate cancer cells by low pH, low glucose environment

Background: Hypoxia, lack of nutrients and high aerobic glycolysis creates a microenvironment of high lactate, low glucose and low pH conditions within a solid tumor. The purpose of the current research is to study how the cancer cells adapt to a microenvironment with low pH, low glucose and high lactate levels with selective growth advantages.

Methods: We simulated solid tumor microenvironment conditions by making DMEM media with low glucose (2mM), high lactate (10mM) and low pH (6.5). To study the growth advantages of this microenvironment, we determined the effect of low pH, low glucose and lactate medium on EGFR activation. Prostate cancer (PC3) cells were grown in six-well plates in 10% serum containing DMEM and serum starved overnight before they were changed to experimental medium. Control cells were grown in normal DMEM. We treated PC3 cells growing in normal DMEM and experimental medium with EGF at 1ng/ml. Protein samples were collected at different time intervals and subjected to western blotting to observe the activation of EGFR by using phospho EGFR antibody. EGFR and actin antibodies were used as control and loading controls, respectively.

Results: Robust and sustained phosphorylation of EGFR for longer time was observed with EGF treatment when the cells were grown in low pH, low glucose and high lactate medium when compared with the cells grown in normal DMEM medium.

Conclusion: The robust activation of EGFR with low pH, low glucose and high lactate medium suggest that the microenvironment containing high lactate provides growth or survival advantages to the cancer cells.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 993. doi:10.1158/1538-7445.AM2011-993