In a new development, scientists have weaponized patients’ own immune cells to combat metastatic colon cancer. This innovative approach, which genetically enhances lymphocytes to target and destroy cancer cells, has shown promising results in a recent National Institutes of Health (NIH) trial. Lymphocytes, a type of white blood cell generated in bone marrow, are found in blood, lymph tissue, and lymphoid organs like the thymus, spleen, and lymph nodes.
The two main types are B-cells, which produce antibodies to attack invading pathogens, and T-cells, which destroy virus-infected or cancerous cells. The new therapy builds on successes with chimeric antigen receptor (CAR) T-cell and tumor-infiltrating lymphocyte (TIL) therapies, extending their application to solid tumors. CAR T-cell therapy uses T-cells from a patient’s blood, while TIL therapy uses T-cells from a patient’s tumor.
Doctors then grow and strengthen more of these cells before returning them to the body to attack the cancer. The new approach isolates specific T-cell receptors that recognize unique tumor antigens, creates modified lymphocytes in a lab, and reintroduces them into the patient’s body. The study included seven participants with metastatic colon cancer.
Three patients showed tumor shrinkage, primarily in the liver, lungs, and lymph nodes. Sustained tumor control was up to seven months. About 20 percent of immune cells in one patient still carried the engineered receptors two years post-treatment.
“The fact that we can take a growing metastatic solid cancer and get it to regress shows that the new cellular immunotherapy approach has promise,” Dr. Steven Rosenberg, chief of the Surgery Branch at the National Cancer Institute and lead author of the study, said in a press release. However, he added that these findings are preliminary and need further refinement and testing in more types of solid cancers.
The ongoing trial now includes patients with various solid tumors. This trial tested a personalized cellular immunotherapy, distinct from immune checkpoint inhibitors, a type of immunotherapy that blocks proteins that stop the immune system from attacking cancer cells. Most colon cancers are microsatellite stable (MSS) or “MMR proficient,” and they typically don’t respond to standard immunotherapies such as checkpoint inhibitors.
MSS refers to the condition of DNA in tumor cells. In MSS tumors, the DNA remains stable with few mutations. This contrasts with microsatellite instability (MSI), where tumor DNA is unstable and highly mutated.
Doctors often test for MSS in colorectal cancer to help guide treatment decisions. This treatment combines personalized medicine and immunotherapy—“the best of two worlds,” Kuang said. Getting responses in several of seven colon cancer patients is a “huge sign of hope,” he noted.
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