NIH researchers have achieved a significant breakthrough in cancer immunotherapy, successfully using patients' own immune cells to target gastrointestinal cancers in a clinical trial published in Nature Medicine. The personalized treatment approach demonstrated tumor shrinkage in approximately one-quarter of patients with colon, rectal, and other GI cancers.
Led by immunotherapy pioneer Dr. Steven Rosenberg, the study represents a crucial step toward addressing one of oncology's most persistent challenges: extending the success of cell-based immunotherapies from blood cancers to common solid tumors that account for the majority of cancer deaths.
"I think this is a very exciting study," said Patrick Hwu, president of the Moffitt Cancer Center in Tampa, Florida, who was not involved in the research. "There's still a lot of work to do... but this is a really great start in the right direction."
Innovative Approach to Solid Tumors
Until now, cell-based immunotherapies have shown remarkable efficacy against blood cancers like leukemia but have struggled to impact solid tumors in organs such as the breast, brain, lungs, pancreas, and gastrointestinal tract.
The NIH team's approach evolved through multiple iterations. Their initial attempt to apply melanoma-based tumor infiltrating lymphocyte (TIL) methods to GI cancers failed completely in 18 patients. In a second phase, researchers sequenced each patient's tumor mutations and used this information to identify and expand specific TILs that could target those particular cancer cells. This refined approach showed modest results, with tumor shrinkage in three of 39 patients.
The breakthrough came in the trial's final stage when researchers added pembrolizumab, an immune checkpoint inhibitor that removes inhibitory signals from immune cells. This combination therapy resulted in clinical responses in eight of 34 patients.
"Right now, only a few labs in the country can do what they just did," noted Dr. Hwu, highlighting the technical sophistication of the approach.
Technical Details of the Immunotherapy
The treatment utilizes tumor infiltrating lymphocytes (TILs) – immune cells naturally present within tumors but typically not in sufficient quantities to effectively combat cancer. The NIH protocol involves:
- Sequencing the patient's tumor to identify specific mutations
- Isolating TILs from the patient's tumor tissue
- Identifying and expanding the specific TILs that recognize the patient's unique tumor mutations
- Administering these expanded cells back to the patient
- Adding pembrolizumab to enhance immune cell activity
This personalized approach represents a significant advancement over previous cell-based therapies, as it targets the specific genetic mutations present in each patient's cancer.
Impact on Patient Care
For patients with advanced GI cancers who have exhausted standard treatment options, this experimental therapy offers new hope. Natalie Phelps, a 43-year-old mother of two from Bainbridge Island, Washington, is among those waiting to participate in the trial. Diagnosed with colorectal cancer five years ago, she has undergone extensive treatments including major surgery, brain radiation, multiple liver surgeries, and 48 rounds of chemotherapy.
"When I was invited out, just to be screened, I was overjoyed. I felt like I won the jackpot," Phelps said about her visit to the NIH Clinical Center in Bethesda, Maryland.
Research Challenges Amid NIH Staffing Changes
Despite the promising clinical advances, the research faces significant operational challenges. Recent staffing reductions at NIH have begun to impact patient care and research progress. Two patients' treatments using the experimental therapy have already been delayed due to reduced capacity for producing personalized cell therapies.
"Everything I try to do, I try to do at warp speed. These are people with desperate illnesses and nowhere to go," Rosenberg explained. "Right now, assuming things don't get any worse, it would be a month [delay]. These are not patients that have very many months left."
Two scientists involved in the specialized process of preparing cells for patients' treatments were recently dismissed, and nine highly skilled scientists on Rosenberg's team face uncertain futures with appointments that need renewal in 2025 or early 2026.
Historical Context and Future Directions
The current breakthrough builds on decades of immunotherapy research. In 2017, the first CAR-T cell therapy – based on genetically engineered immune cells – was approved for blood cancers. Last year, a TIL-based therapy received approval for metastatic melanoma.
Rosenberg's work has been instrumental in advancing both approaches. His team is already working to refine and improve upon the current results for GI cancers, aiming to increase response rates and extend the therapy to other solid tumors.
"Very rarely does research work in a straight line – you have ideas, you pursue them, most things do not work, some things do work. You build upon them," Rosenberg said, emphasizing the iterative nature of scientific progress.
For patients like Phelps, who is waiting for one of her tumors to grow large enough to meet the trial's size criteria, the research timeline is critical. "It's one thing that seems unfair: Why would a metastatic cancer patient need any more stress?" she asked. "Why slow down the research when cancer rates are on the rise, particularly with young people under 50?"
The study represents a significant milestone in cancer immunotherapy, potentially opening new treatment avenues for patients with common solid tumors who currently have limited options. As researchers continue to refine the approach, the hope is that response rates will improve and more patients will benefit from this personalized form of cancer treatment.
