Laser Therapy Breakthrough May Extend Survival in Aggressive Brain Cancer

Brain Cancer Regions (File Photo- Bruce Blaus)

Keck Medicine of USC researchers have reported striking early results from a clinical trial that could reshape treatment for one of the deadliest brain cancers.

By News Desk

High-grade astrocytoma — including glioblastoma — is a fast-growing, aggressive cancer that almost always returns after surgery. Once it recurs, patients typically survive only four to five months. Standard therapies offer limited hope, and immune checkpoint inhibitors, which have revolutionized treatment for many cancers, have largely failed in brain tumors.

The reason: the blood-brain barrier. This tightly sealed protective layer prevents immune cells from easily reaching tumors in the brain, limiting the effectiveness of drugs designed to activate cancer-fighting T-cells.

But in a Phase 1/2b trial published in Nature Communications, investigators combined a minimally invasive laser procedure known as laser interstitial thermal therapy (LITT) with the immune checkpoint inhibitor pembrolizumab — and the results were dramatic.

Nearly half of the patients treated with LITT followed by pembrolizumab were still alive 18 months later. By contrast, none of the patients who received conventional surgery followed by pembrolizumab survived to the 18-month mark. More than one-third of patients receiving the combined therapy lived longer than three years — far beyond the typical survival window for recurrent high-grade astrocytoma.

The key appears to be heat.

Using MRI guidance, neurosurgeons insert a probe directly into the tumor and apply targeted laser heat. The heat destroys tumor tissue while temporarily disrupting the blood-brain barrier for several weeks. That window allows tumor materials to enter the bloodstream and alerts T-cells to the cancer’s presence. Once activated by pembrolizumab, those T-cells can cross back into the brain and attack the tumor.

Lead author Dr. David Tran, chief of neuro-oncology at Keck Medicine and co-director of the USC Brain Tumor Center, said the findings suggest LITT may enable immune therapies to work in brain cancers where they previously failed.

The trial enrolled 45 patients, all facing advanced recurrences of astrocytoma. The combination treatment was found to be generally safe and well tolerated.

Since the study began, the U.S. Food and Drug Administration has cleared LITT for certain brain tumors, and pembrolizumab has already been approved for several cancers. The trial was conducted at three sites nationwide, including Keck Medicine of USC, Washington University in St. Louis and the University of Florida.

For patients with few remaining options, the approach could represent a meaningful step forward — and a rare source of hope in a disease long marked by grim statistics.