SEP 07, 2016 8:24 AM PDT

Moving Away from Chemo: New Approach to Cancer Immunotherapy

WRITTEN BY: Jennifer Ellis
Why isn’t our immune system able to fight off cancer? This is a tough question cancer researchers have long been working on, and we are getting closer to figuring it out. When treating cancer, doctors are looking to immunotherapy and other alternatives to help target actual tumors instead of attacking all rapidly dividing cells in a patient’s body with chemotherapy. Immunotherapy uses the immune system to recognize and destroy specific tumors or spreading cancer cells. Many immunotherapies to date activate and strengthen the adaptive immune system, similar to how vaccines allow protection to specific diseases. While these treatments have had some success, they are slow to develop as each therapy is very specific to a unique and known protein.

Scanning electron microscope image of immune cells attacking a cancer cell (mskcc.org)

Carolyn Bertozzi of Stanford University has recently introduced a new approach to immunotherapy, activating another arm of the immune system, the innate immune system. The innate immune system, or non-specific immune system, provides general defense from infection by identifying and removing foreign bodies. Bertozzi hypothesized that there must be a way to push the immune system to recognize cancer cells more frequently and in a more general manner, based not only on protein recognition but on the sugars fixed to the outside of the cells. The study is published online in the Proceedings of the National Academy of Sciences.

The Bertozzi lab studies the glycocalyx, or sugars that surround cells, and how these sugars interact with the immune system. Cancer cells tend to be overlooked by the immune system as normal healthy cells, allowing them to metastasize and proliferate uncontrolled. New thinking highlights sugars surrounding cancer cells as part of the problem.

“This is a whole new dimension to immune therapy,” Bertozzi says, “People in this field are starting to appreciate that there are many different nodes that you need to affect to get a more robust immune reaction against a tumor, and the glycocalyx appears to be one of those nodes.”

It has long been known that certain sugars and proteins aid in masking cancer cells from the immune system. Bertozzi wanted to find out specifically what role sugars play in helping cancer cells hide. She discovered that if certain sugars are present on cancer cells, therapies are less likely to be effective, and that these sugars can act as a signal to the innate immune system to ignore the cells. Sialic acid is one type of sugar associated with spreading cancer cells. Researchers in the Netherlands showed that excessively high sialic acid expression in cancer cells can affect undetected tumor growth and initiation of metastasis.

By removing sialic acid from the cancer cell surface, Bertozzi was able to trigger the innate immune system. The team used the common cancer therapy Herceptin, an antibody that binds to the HER2 protein expressed on some breast cancer cells, flagging the cell for destruction by natural killer (NK) cells. Bertozzi attached a chemical “cleaver” to the Herceptin antibody to create an antibody-enzyme conjugate. Once the antibody bound to the HER2 protein, the cleaver could cut off any nearby sugars on the cell surface. This lack of sugars decreased the mask on the tumor cells, allowing the innate immune system to recognize and destroy the cells more frequently. Essentially, Bertozzi discovered that the less sugars around a cancer cell, the more activation she saw from the immune system to destroy cancer cells.

This new approach provides a boost to cancer treatments by enabling current therapies to work more effectively on a broader range of patients. Not only could this method be applied to HER2 proteins using Herceptin making it more successful when less HER2 is expressed, but also potentially applied to a variety of other expressed proteins and sugars. This study was done in cell culture, providing a solid foundation for additional testing and the creation of new cancer treatments in patients. The approach brings to light a new way of thinking about the complex relationship between the innate immune system and cancer cells, and opens the door to advancing cancer immunotherapy.

Sources: Stanford Report, PNAS, NCBI
 
About the Author
  • I love all things science and am passionate about bringing science to the public through writing. With an M.S. in Genetics and experience in cancer research, marketing and technical writing, it is a pleasure to share the latest trends and findings in science on LabRoots.
You May Also Like
MAR 22, 2021
Cancer
Can we use our own bacteria to fight cancer?
MAR 22, 2021
Can we use our own bacteria to fight cancer?
New research highlighted recently in Nature explores the ways that bacteria in tumors could be targeted to trigger immun ...
APR 08, 2021
Cancer
What can modifiying cultured cells to act more like normal cells teach us about cancer?
APR 08, 2021
What can modifiying cultured cells to act more like normal cells teach us about cancer?
A team from the University of Louisville has developed a technique to make cell cultures act more like normal cells. Thi ...
MAY 13, 2021
Immunology
Tumors Hide From the Immune System by Masquerading as Baby Cells
MAY 13, 2021
Tumors Hide From the Immune System by Masquerading as Baby Cells
The immune system is programmed to recognize foreign bodies as potentially dangerous, promptly removing them before the ...
MAY 10, 2021
Cell & Molecular Biology
Getting RNA-Based Medicine Past the Blood-Brain Barrier
MAY 10, 2021
Getting RNA-Based Medicine Past the Blood-Brain Barrier
RNA molecules serve several functions, one of which is to help the cell generate proteins from active genes. It also may ...
JUN 07, 2021
Health & Medicine
Higher Incidence of Breast Cancer in Polluted Urban Areas
JUN 07, 2021
Higher Incidence of Breast Cancer in Polluted Urban Areas
A Taiwanese study looked at the incidence of breast cancer in areas of Taiwan with varying levels of air pollutants. Air ...
JUN 01, 2021
Cancer
No level of secondhand smoke is safe for pregnant women
JUN 01, 2021
No level of secondhand smoke is safe for pregnant women
A study published recently in Environmental Health Perspectives concludes that no amount of exposure to secondhand smoke ...
Loading Comments...