In what scientists are calling a “crack in the solid wall of cancer,” a new form of personalized immunotherapy has shown promising results in shrinking tumors in patients with hard-to-treat gastrointestinal cancers. 

The treatment, developed by the National Institutes of Health (NIH), uses the body’s own immune cells—called Tumor Infiltrating Lymphocytes (TILs)—to attack and destroy cancer cells.

The clinical trial results, published in Nature Medicine, involved 91 patients with advanced cancers of the colon, rectum, pancreas, bile duct, and other parts of the digestive system. Most of these patients had already undergone multiple rounds of chemotherapy without success.

Researchers said nearly 24% of patients who received selected TILs combined with an immune-boosting drug called pembrolizumab (Keytruda) saw a significant reduction in tumor size, compared to just 7.7% of those who received the TILs alone. Those who got unselected TILs—meaning the immune cells weren’t specifically trained to attack the tumor—showed no improvement at all.

“We’re seeing the first extension of cellular therapy with TILs into the common solid cancers. We see a little crack in the solid wall of cancer… and we think we have ways to open that crack even further.” Dr. Steven A. Rosenberg, the lead investigator of the study and a pioneer in cancer immunotherapy, said, quoted by the National Institutes of Health in a report.

Therapy for Tough Cancers

Importantly, the study showed that patients with pancreatic, bile duct, rectal, and colon cancers -cancers that usually don’t respond well to current therapies – did benefit from this approach.

While some of the responses lasted just a few months, others continued for up to 5.8 years, giving fresh hope for long-term survival in these aggressive cancers. However, serious side effects were seen in about 30% of the patients, highlighting the need for careful monitoring.

The researchers are now working on improving the technique by identifying TILs that target multiple specific proteins within a tumor, known as neoantigens, which could make the treatment more widely effective.

“I’m very excited about this approach to treating cancer,” Rosenberg told Healio, a health publication. “I see it as the approach most likely to result in significant improvements in the future.

Last year, the FDA approved the first TIL therapy for solid tumors, lifileucel (Amtagvi), for advanced melanoma. This new study suggests that a similar approach might soon be possible for a broader range of solid cancers.

As research continues, the study’s authors hope this could lead to a paradigm shift in how we treat metastatic gastrointestinal cancers, making the once-impossible task of turning the immune system into a precision weapon against cancer a new reality.

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