Why do new cancer treatments fail?
New cancer treatments based on immunotherapy, the practice of using a patient’s own immune system to treat disease, have sometimes demonstrated outstanding results. But for all of the instances where immunotherapy produced shocking remissions, there are also instances where it has not proved as effective.
Researchers have identified a few potential causes of a lack of response to immunotherapy. Some tumors have mutations that limit their response to immune system cells. Others produce cells or chemicals that suppress the immune system. Still others are made up of cancer cells that are genetically quite different from each other, which makes them harder to target using immunotherapy.
Each of these challenges presents difficulties for researchers developing new immunotherapy treatments. In a step toward addressing them, researchers in Boston developed a new model to test immunotherapeutic approaches, publishing their research in Oncoscience.
A new way to test cancer treatment
In order to test methods of overcoming barriers to effective immunotherapy, researchers need to have tumors to test on. The researchers have developed just such a method of testing by using mice.
Glioblastoma, a brain tumor, is an especially deadly form of cancer with a five-year survival rate under 5%. By studying mice with immunotherapy-resistant glioblastoma, researchers hope to identify and overcome immunotherapy challenges.
The mouse-model in question displays several key characteristics of drug resistance. It has a relatively low response to the immune system, suppresses the immune system in the vicinity of the tumor, and grows rapidly. These characteristics make the model an excellent testing ground for new approaches.
Testing in this model showed that combining immunotherapy treatments may be the answer. Combining several different immunotherapy treatments showed a greater effect on tumors. When the immune system is better able to penetrate and enter the tumor, as is the case with this more varied attack, the effect on cancer is more pronounced.
The authors state that “testing [treatments] in combination with other immunotherapies, and expanding clinical development to patients with minimally immunotherapy responsive lethal cancers” will be essential to finding effective immunotherapy treatments for hard-to-treat tumors.