Arginine may combat immunosuppression in glioblastoma
A common amino acid may help restore function to cancer-fighting T-cells in persons with glioblastoma, say researchers.
Immunotherapy has become a focus of recent glioblastoma research due to the potential for combined target specificity and sensitivity. However, a major potential pitfall of this approach is the known suppression of cellular immunity seen in patients with this deadly form of brain cancer, explain Allen Waziri, MD, of the University of Colorado Cancer Center in Denver, and colleagues in Clinical Cancer Research (2011;17:6992-7002; http://clincancerres.aacrjournals.org/content/17/22/6992.full.pdf+html).
Neutrophils often stop the immune response in persons with glioblastoma by persistently secreting the enzyme arginase. Arginase deletes arginine, an amino acid upon which T-cells are critically dependent for activation and function. Waziri's team found that the arginase was not directly responsible for blunting T-cell activity in glioblastoma patients; rather, the resulting lack of arginine suppresses the immune system in these patients.
The researchers are now conducting a phase 0 clinical trial in persons with newly diagnosed glioblastoma to explore whether a week-long, high-dose course of arginine before cancer surgery can allow an immune system that previously missed cancer cells to recognize and attack those cells.