Deep inside a lung tumor, immune cells called macrophages face a choice: defend the body or feed the cancer. Researchers at Justus Liebig University Giessen have discovered what controls that choice—and it's a naturally occurring molecule called itaconate that can flip the switch toward survival.
Lung cancer remains one of the deadliest cancers worldwide, and the battlefield where it thrives matters as much as the tumor itself. The tumor microenvironment—the tissue surrounding a cancer—shapes whether immune cells become defenders or enablers. Macrophages, the immune system's scavenger cells, can swing either way, actively fighting tumors or unwittingly supporting their growth. Understanding what tips this balance could transform how we treat cancer.
An international team led by Prof. Dr. Rajkumar Savai of Justus Liebig University Giessen, working with the Institute for Lung Health in Giessen and the Max Planck Institute for Heart and Lung Research in Bad Nauheim, identified the mechanism behind this switch. Their finding, published in Cell Metabolism, centers on itaconate—a molecule the body produces naturally. In healthy tissue around tumors, itaconate levels are remarkably low. This deficiency is no accident; it allows macrophages to adopt a pro-tumoral state that shields cancer cells and accelerates their growth.
When the research team artificially boosted itaconate concentrations in tissue samples and mouse models, the transformation was striking. Macrophages switched to an anti-tumoral form, becoming active fighters that slowed tumor growth. The immune system, given the right metabolic signal, shifted from complicity to combat.
But itaconate's power goes further. The researchers discovered that a variant called octyl-itaconate attacks cancer cells directly, independent of immune activation. It blocks G6PD, a critical enzyme that lung cancer cells depend on for their metabolism. Starved of this enzymatic fuel, tumor cells lose their capacity for rapid multiplication. The cancer weakens from the inside and the outside simultaneously.
"Our results show that by specifically influencing metabolism, we can both strengthen the immune system and directly weaken the cancer cells," says Prof. Savai. What makes this finding particularly compelling is that the effect held true not just in mice, but in human lung tissue samples. That translation from laboratory to human biology signals genuine clinical potential.
This research sketches the outline of a new therapeutic strategy: drugs designed to restore itaconate levels could simultaneously activate a person's own immune defenses while metabolically crippling the tumor. Rather than attacking cancer from a single angle, this approach exploits both biological fronts—reprrogramming immune cells while depriving cancer cells of the resources they need to survive.
Lung cancer patients have endured decades of incremental progress in survival rates. This discovery—that a single metabolic adjustment can reprogram immunity and starve tumors—offers a more elegant path forward. The work now shifts to transforming this understanding into drugs that can be taken to patients, but the metabolic principle is clear: sometimes the most powerful way to fight cancer is to speak the body's own chemical language.