Researchers isolate cells that weaken immune response to cancer

Researchers at the University of Colorado are working on a new form of immunotherapy that would use cells originating in the spleen to fight against cancer.

This new immunotherapy would stifle the work of myeloid-derived suppressor cells (MDSCs), which soothe the immune system and are increased in the presence of cancer cells to decrease the body’s immune response to fight against cancer.

The study, published in Cancer Immunology & Immunotherapy, details how researchers at the University of Colorado Cancer Center used previous studies on mouse splenocytes that showed cancer boosted the number of these cells. Similar results were found in human cancer patients.

MDSCs are immune cells that originate from bone marrow cells and develop in the spleen. While in the spleen, these so-called splenocytes are “programmed.” While the exact function of these cells isn’t clear, cancer patients with high levels of MDSCs tend to have poor prognoses and decreased responses to therapy.

Splenocytes are more abundant and easier to isolate in mice than in humans, making previous studies of this type of response difficult. Not only did the research team draw a correlation between the work of splenocytes in mice and humans, but also new methods for isolating human splenocytes.

The research team at the University of Colorado was able to prove that splenocytes had an immunosuppressive response in humans, blocking the work of T-cells in fighting against cancer, according to the report.

Other cancer therapies exist that use T-cells to fight cancer, but this study shows that the work of MDSCs might weaken the response of those T-cells and other cancer-fighting immune cells.

The study findings help to explain why only 20% to 40% of patients respond to existing immunotherapy, and could pave the way for new treatment to weaken the power of MDSCs in suppressing the T-cell’s response to cancer.

Next: Still work to be done

Still work to be done

Martin McCarter, MD, of the University of Colorado Cancer Center and surgical oncologist at the University of Colorado Hospital, led the study and told Medical Economics that it’s too soon to predict when this type of therapy might be available to physicians or to what extent it would be effective. However, his research team has already conducted a small-scale clinical trial to show a proof of principal to target MDSCs.

“It appears we are able to target MDSCs in combination with standard of care immunotherapy,” Martin said of that study. “The final analysis is being done now with a manuscript to follow. A follow-up trial is being planned.”

While the trial was conducted primarily in melanoma patients, Martin said if proven successful the therapy could theoretically be applied to any type of cancer.