GRAND RAPIDS, Mich. (WOOD) — Researchers at the University of Michigan believe they are closer to a breakthrough that could potentially help more than half of the world’s cancer patients.

In a study published last month in the academic journal Cancer Cell, the research team reports they have identified a metabolic mechanism that tends to block the body’s natural immune response and makes immunotherapies ineffective.

Weiping Zou, a senior author on the study and the executive director of the Michigan Center for Excellence for Cancer Immunology and Immunotherapy, said the extremely complex system can be broken down into simple terms.

“(Immunotherapy uses) your own immune system to kill the tumor cells,” Zou told News 8. “We have T-cells in our immune system. T-cells are the soldiers of the immune system. They recognize tumor cells and they kill tumor cells.”

But currently, only 20% to 30% of cancer patients respond well to immunotherapy. Zou and his team are working to figure out why, and how to overcome that.

Zou and the team identified a protein that transports one specific metabolite within cancerous cells that allows the cell to resist those attacks by the T-cells. In the study, the researchers proved that tumor samples with high levels of a specific protein, called SLC13A3, was prevalent in patients who had a poor response to immunotherapy and a lower survival rate.

After confirming the findings with tests on multiple types of cancers, the research team experimented on mice. The animals grew tumors where the SLC13A3 protein was suppressed. In those cases, tumor development slowed. Once the protein was “restored,” the tumor development rate returned back to previous levels.

“That’s why we feel this is not only scientifically important, but we have some levels of application,” Zou said.

While the SLC13A3 protein is a promising target, more work needs to be done to determine other effects caused by the protein inhibitor.

“The next steps involve assessing the toxicity of this inhibitor in natural animals and also in humans,” Zou said. “It is still far away from real application, but as we know, future cancer treatment will rely on innovative immunotherapies. This may be one way to go.”