What is immunotherapy and how does it treat cancer and other conditions? | Immunology
What is immunotherapy?
Immunotherapies are biological treatments that harness the immune system to prevent, control and fight diseases and other conditions. The best-known vaccines are those that train the immune system to recognize targets such as invading pathogens. Other immunotherapies boost immune responses when they are too weak or dampen them when they are out of control. Still others rely on artificial immune cells or laboratory-made antibodies to disrupt disease processes.
When were they invented?
Efforts to prevent disease by strengthening the immune system date back thousands of years, but advanced therapies for a wide range of diseases have emerged over the past two decades. A global clinical trial registry listed 1,257 immunotherapy trials between 2006 and 2016. This figure increased to 4,591 over the past decade. “It’s really exciting. People are starting to realize how important the immune system is,” says Adrian Liston, an immunologist and professor of pathology at the University of Cambridge. “This is the era of immunology.”
How do cancer immunotherapies work?
Cancer patients have seen great benefits from immunotherapies, and dozens of them are now approved for more than 30 types of cancer. Some tumors evade the body’s defenses by turning off immune cells, but antibody drugs – called checkpoint inhibitors – reactivate them so they can recognize and attack malignant tumors. Highly mutated or “hot” cancers like melanoma may respond particularly well, but not in all patients.
Why some patients do well and others barely respond is an important puzzle that researchers hope to solve with a four-year study launched last week. The project will recruit thousands of patients with breast, bladder, kidney and skin cancer to find out what factors affect their outcomes.
Other antibody drugs attack cancer differently. A drug called herceptin binds to breast and stomach tumors and signals them for destruction, while blocking chemical signals that indicate cancer growth. Another extremely promising area is cancer vaccines, many of which are based on the mRNA technology used in Covid shots. More than 100 cancer vaccines, which stimulate the immune system to attack tumors, are currently in trials.
Other therapies harness immune cells themselves. In 2018, doctors treated a woman with metastatic breast cancer by harvesting immune cells infiltrated from her tumors. They grew billions of cells in the lab and injected the most potent ones back into his bloodstream. Another approach called Car-T cell therapy allows patients’ immune cells to hunt down cancer cells. Last month, Jurassic Park actor Sam Neill announced he was cancer-free after undergoing treatment for stage 3 blood cancer as part of a trial.
Samra Turajlić, director of the Cancer Research UK Manchester Institute and head of the Cancer Dynamics Laboratory at the Francis Crick Institute in London, says there has been a conceptual shift around the disease. “We increasingly view cancer as something that is shaped by the immune system,” she says. “In fact, the onset of cancer is due to the inability of the immune system to eliminate it in the first place. »
Can they treat other conditions?
Cancer immunotherapies tend to intensify immune attacks; immunotherapies for other conditions aim to alleviate them. The simplest treats allergies such as hay fever and peanut intolerance by exposing people to small but increasing amounts of allergy-triggering proteins. A recent trial in China aimed to alleviate egg allergy by feeding people pancakes.
Researchers are currently testing whether existing immunotherapies can help a wider range of patients. This week, a team from Bristol described giving tocilizumab, an immunotherapy for rheumatoid arthritis, to people suffering from depression. The study was too small to say whether it worked, but researchers were encouraged by hints of improvements in depression severity, fatigue, anxiety and quality of life.
Some of the most exciting new immunotherapies build on last year’s Nobel Prize-winning work on regulatory T cells, or Tregs. Humans have dozens of different immune cells that attack invading pathogens, but Tregs are unusual: They shut down the immune system once the threat has been dealt with.
Liston, co-founder of a Cambridge spinout called Aila Biotech, is developing a Treg therapy for multiple sclerosis, a disease caused by immune cells mistakenly attacking the nervous system. The therapy aims to stimulate Tregs in the brain to reverse the attack. The same approach could reduce swelling after head trauma, he says.
The potential of Tregs is vast. Therapies are in the pipeline to combat dementia and autoimmune diseases, from type 1 diabetes and rheumatoid arthritis to lupus and chronic inflammation. A therapy being developed by Peter Eggenhuizen of Monash University uses Tregs to treat inflammatory bowel disease, a condition that affects at least 7 million people worldwide.
“Probably half of all deaths have an immunological component,” Liston says. “It’s an underlying theme in aging, autoimmune diseases, allergies, infectious diseases and inflammatory diseases like diabetes. But one of the great things about the immune system is that it’s very easy to modify. We can tailor it to our goals.”
