BY THE OPTIMIST DAILY EDITORIAL TEAM

Cancer immunotherapy has transformed treatment for some patients. For the 60 to 80 percent who don’t respond, the problem often isn’t the killer T cells at the end of the immune chain. It’s the cells responsible for training them. A new UCLA study published in iScience identifies creatine, the supplement commonly used by athletes and bodybuilders, as a critical fuel source for those training cells, and finds that supplementing with it significantly slowed tumor growth in mouse models.

Why dendritic cells are the missing link in immunotherapy

Killer T cells are the immune system’s frontline fighters against cancer. But before they can act, dendritic cells must capture fragments from tumors, carry those fragments to T cells, and direct them toward the target. Most approved cancer immunotherapies skip this step and go straight for T cells. That may be why so many patients don’t respond.

The UCLA team, whose earlier work showed that creatine fuels killer T cells in tumor environments, turned its attention to dendritic cells after noticing something in the metabolic data. When the researchers looked at which genes were most active in dendritic cells that had infiltrated tumors in mice, one stood out: the gene for the creatine transporter, a protein that pulls creatine into cells, was significantly elevated in tumor-infiltrating dendritic cells compared to those in healthy tissue.

What creatine deprivation and supplementation revealed

To find out what that meant, the team removed the creatine transporter from dendritic cells entirely. Those cells showed impaired survival, reduced activation, and a weakened ability to prime T cells for a tumor response. When creatine-deficient dendritic cells were grown alongside T cells in the lab, the T cells divided less and produced fewer of the signaling molecules cancer-fighting requires.

The team then ran the opposite experiment. Daily creatine injections in mouse models of melanoma significantly slowed tumor growth, boosted the number of dendritic cells inside tumors, and increased their activation. Creatine-treated dendritic cells also produced more of the chemical signals that draw additional immune cells into the tumor microenvironment.

Metabolomics analyses pointed to the mechanism: creatine raised intracellular ATP levels in dendritic cells. ATP is what cells use to power nearly every function. Creatine acts like a battery, releasing stored energy when demand spikes, which helps dendritic cells hold their metabolic position even while competing with fast-growing tumor cells for nutrients. The inflammatory signaling pathways needed for activation stay on.

“What this study shows is that creatine doesn’t just help the T cells fighting cancer — it also energizes the entire infrastructure that supports and guides them,” said Lili Yang, the study’s senior author and a professor of microbiology, immunology and molecular genetics at UCLA. “That makes creatine a promising supplement to holistically support the immune response that modern immunotherapies depend on.”

Human cell results and implications for cancer vaccines

The same pattern held in human cell experiments. Creatine enhanced the activation of human monocyte-derived dendritic cells, a type commonly used to make dendritic cell cancer vaccines, and improved their ability to stimulate human T cells against a cancer-associated target. The team suggests incorporating creatine into the manufacturing process for those vaccines could increase their potency before a patient ever receives them.

Co-first author James Elsten-Brown described the two directions the research points toward: “creatine could be used in two complementary ways: as a supplement to enhance the immune response of patients already receiving immunotherapy, and as a tool to improve the quality of dendritic cell-based vaccines before they’re administered.”

Clinical outlook and important caveats for patients

This research was done in mouse models and human cells, not in patients. No clinical recommendations follow from it, and anyone undergoing cancer treatment should check with their physician before adding any supplement to their routine.

Creatine monohydrate has been used as a supplement for decades and is generally regarded as safe at recommended doses. Because that safety profile is already established, the bar for clinical testing is lower than it would be for a new drug. The team is working with physicians toward prospective trials to test whether creatine supplementation improves outcomes in patients receiving immunotherapy.

“Understanding how to metabolically support dendritic cells is about supporting the entire anti-tumor response, not just the killer T cells at the end of it,” said co-first author Elliot Kang. Rather than layering another intervention onto T cells directly, this approach works upstream. If the results translate to humans, creatine could turn out to be one of the least expensive components in an immunotherapy protocol.

Source study: iScience – Creatine uptake promotes dendritic cell activation and enhances antitumor immunity

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