The Challenge of Immunotherapy: Why T Cells Get "Exhausted"
Engineered T-cell therapies, including chimeric antigen receptor (CAR) T-cell therapy and T-cell receptor (TCR) therapy, have transformed treatment for certain blood cancers and are increasingly being investigated for solid tumors. These treatments involve collecting a patient's immune cells, genetically modifying them in the laboratory to recognize cancer, and infusing them back into the patient to attack tumors.
Despite their success, one of the biggest challenges is T-cell exhaustion—when immune cells gradually lose their ability to multiply and attack tumors after repeated exposure to cancer. The preparation process itself can also cause cells to mature too quickly, making them less likely to survive and remain effective over time. Scientists have been searching for ways to help these cells function longer and maintain their cancer-fighting abilities.
Research Highlight: A New Role for p53
Researchers at the UCLA Health Jonsson Comprehensive Cancer Center turned their attention to p53, a protein best known as the "guardian of the genome" for its role in preventing cancer. Its role in regulating human T cells, however, is less understood.
The study, published in Frontiers in Immunology, found that temporarily activating p53 during the preparation of human T cells helped immune cells develop characteristics associated with longer-lasting immune responses. Specifically, treated cells showed:
- Fewer molecular signs of exhaustion;
- Greater energy reserves;
- More effective killing of melanoma cells in the laboratory.
How the Study Was Conducted
The team used an investigational drug called navtemadlin, which blocks another protein called MDM2 that normally keeps p53 levels under control. By blocking MDM2, the drug increases p53 activity. Researchers compared treated and untreated T cells to determine how the drug affected their development, energy production, and ability to fight cancer.
The team also genetically engineered T cells to recognize a protein found on certain melanoma cells and monitored the cells for nearly seven days using specialized imaging equipment.
Key Findings: Younger, Stronger Fighters
Results showed that T cells treated with navtemadlin were more likely to develop into central memory T cells, which have a greater ability to survive and multiply when they encounter their target again. The cells were also more likely to produce two important cancer-fighting proteins—interferon-gamma and granzyme B—which help immune cells coordinate an attack and destroy cancer cells.
Most importantly, when tested against melanoma cells, engineered T cells prepared with navtemadlin began clearing cancer cells more effectively after approximately 40 hours and maintained their advantage throughout the experiment—without additional interleukin-2, a protein commonly used to support T-cell growth.
The study also highlighted that dosage matters: lower concentrations of navtemadlin promoted healthy memory T-cell development without substantially reducing viable cell numbers, while higher concentrations caused more cell death, underscoring the need to carefully control p53 activation.
What This Means
The findings suggest that rather than developing an entirely new treatment or introducing additional genetic modifications, researchers could potentially incorporate a drug like navtemadlin into existing manufacturing processes to produce immune cells better equipped to fight cancer. "This is one of the first studies to link p53, one of the most extensively studied proteins in biology, to T-cell exhaustion in humans," said Joseph Crompton, MD, PhD, assistant professor of surgery at the David Geffen School of Medicine at UCLA and senior author of the study. "While p53 has long been known for its role in preventing cancer, our findings suggest it may also play an important role in helping immune cells maintain their ability to fight it."
Everyday Health Management Matters Too
While immunotherapy advances are exciting, for most people, tracking everyday health metrics and maintaining good habits remain the foundation of cancer prevention and overall wellness. You can use the Xiaoshu Health App to sync relevant data from Apple Health, track sleep, activity, and other health indicators, and support your long-term health management.