UCLA Study Links p53 Activation to Enhanced T-Cell Cancer Killing

Researchers at the UCLA Health Jonsson Comprehensive Cancer Center have demonstrated that briefly stimulating a specific protein can markedly improve how engineered human immune cells attack cancer. The findings, published in Frontiers in Immunology, indicate that activating p53 during laboratory preparation helps T cells maintain their potency against melanoma, offering a potential upgrade for existing immunotherapies.

The Challenge of T-Cell Exhaustion

Engineering patient immune cells to identify tumors does not ensure they will sustain that fight. Repeated exposure to cancer often leads to exhaustion, a state where T cells lose their capacity to multiply and strike effectively. Furthermore, standard laboratory procedures used to prepare these cells for infusion can cause them to mature prematurely, diminishing their long-term survival and therapeutic impact.

These limitations affect both chimeric antigen receptor (CAR) T-cell therapy and T-cell receptor (TCR) therapy. Both methods involve harvesting a patient’s immune cells, genetically modifying them in a lab to recognize cancer markers, and reintroducing them into the body to target tumors. While such treatments have revolutionized care for certain blood cancers, researchers are increasingly exploring their application for solid tumors.

P53’s Role in Immune Regulation

The team focused on p53, widely known as the “guardian of the genome” for its role in preventing damaged cells from becoming malignant. Although scientists have extensively studied this protective function, less is understood about how p53 regulates human T cells. The study suggests this protein may also be crucial for helping immune cells retain their ability to combat disease.

To investigate this, the researchers treated human T cells with navtemadlin, an investigational drug that boosts p53 activity by inhibiting MDM2, a protein that normally keeps p53 levels in check. By comparing treated cells with untreated ones, the team assessed changes in development, energy production, and anti-cancer capabilities.

Enhanced Melanoma Cell Destruction

The scientists genetically engineered the T cells to recognize a protein present on certain melanoma cells and monitored their performance using specialized imaging equipment for nearly seven days. The results showed that T cells prepared with navtemadlin were significantly more effective at killing melanoma cells than those left untreated.

This advantage emerged after approximately 40 hours and persisted throughout the experiment. Notably, the treated cells exhibited improved cancer-fighting activity without requiring additional interleukin-2, a protein typically added to support T-cell growth and survival.

“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. This opens up a new avenue for developing more effective cancer immunotherapies.”

Energy Reserves and Memory Formation

The treated cells displayed greater energy reserves and produced higher levels of interferon-gamma and granzyme B, two proteins essential for coordinating attacks and destroying cancer cells. They were also more likely to develop into central memory T cells, which possess a stronger capacity to survive and multiply upon re-encountering their target.

Alongside fewer molecular signs of exhaustion, these characteristics suggested the cells might remain effective for longer periods. However, the experiments tested human cells in a laboratory setting rather than measuring treatment outcomes in patients.

Dose Sensitivity and Manufacturing Potential

Incorporating drugs like navtemadlin during cell preparation could potentially integrate into existing manufacturing processes. This approach offers a way to enhance engineered T-cell therapies without creating entirely new treatments or introducing further genetic modifications.

At lower concentrations, navtemadlin encouraged the development of healthy memory T cells without substantially reducing the overall number of viable cells. Conversely, higher concentrations caused increased cell death, highlighting the need for careful control of p53 activation if this method is adopted clinically.

The study was funded in part by the American College of Surgeons, the UCLA Broad Center of Regenerative Medicine and Stem Cell Research, the UCLA Health Jonsson Comprehensive Cancer Center, the Tower Cancer Research Foundation, the Sarcoma Foundation of America, and the National Cancer Institute of the National Institutes of Health under the Early-Stage Surgeon Scientist Program.