Once cancer cells have spread to lymph nodes, the chances of survival are reduced.
The researchers, from Cornell University in Ithaca, NY, describe how they produced and tested their "super natural killer cells" in a paper published in the journal Biomaterials.
Senior author Michael R. King, a professor in biomedical engineering, says:
"We want to see lymph node metastasis become a thing of the past."
Natural killer cells are a type of white blood cell in the immune system that targets abnormal cells, such as tumor- promoting cells and cells infected with viruses.
Once they recognize their target cell, they latch onto it and then inject toxic molecules into it. These disrupt several processes inside the target cell, triggering apoptosis or cell death.
Prof. King and colleagues have found they can significantly boost this effect by attaching a protein called TRAIL (Tumor necrosis factor Related Apoptosis-Inducing Ligand) to the natural killer cells and turn them into "super killer cells."
The killer cells inject TRAIL into the cancer cells and trigger cell death and disintegration.
In previous work in mice, the team showed that attaching TRAIL to white blood cells in the bloodstream could kill cancer cells entering the bloodstream and stop them spreading to the lung, kidney, liver and other organs.
However, most cancers spread through the lymph nodes, and presence in the lymph node is a way of staging the disease. Once cancer cells reach the lymph nodes, the chances of survival are much reduced.
Eliminated cancer cells in lymph nodes within days
In the new study, Prof. King and colleagues found they could kill cancerous tumor cells in the lymph nodes of mice by injecting liposomes armed with TRAIL that attach to the natural killer cells that reside in the lymph nodes. The super killer cells eliminated the cancer cells within days.
Liposomes are tiny spherical sacs enclosed in a thin membrane that can be used as vehicles for delivering drugs and nutrients to cells.
Prof. King sums up the study:
"In our research, we use nanoparticles - the liposomes we have created with TRAIL protein - and attach them to natural killer cells, to create what we call 'super natural killer cells' and then these completely eliminate lymph node metastases in mice."
He says they now need to test the method in other animal studies and suggests it may be several years before it is ready for human trials.
In the following video, Prof. King describes the work he and his team have been doing with TRAIL to create super natural killer cells.
Doctors use a four-stage system to categorize cancer progress. In stage 1, the tumor is small and localized - the cancer has not yet spread to the lymph nodes. In stages 2 and 3, the tumors are bigger and it is likely that cancer cells have made it to the lymph nodes. Stage 4 cancers are where the cells have traveled through the lymph node and set up tumors in other parts of the body.
In the case of breast, colorectal and lung cancer, 29-37% of patients are diagnosed with metastases in their tumor-draining lymph nodes - that is, their cancer has reached the stage where cells from the original tumor have spread to nearby lymph nodes. These patients are at a much higher risk of the cancer spreading to other organs.
Meanwhile, Medical News Today learned of a gene study that has compiled a catalog of biomarkers for multiple cancers. The researchers say it should lead to biomarker tests for early detection and treatment of cancer.