Breakthrough in Cancer Treatment: New Natural Killer Cells Offer Safer Option
Scientists have made a significant advancement in the fight against cancer by developing new ‘natural killer’ (NK) cells that can effectively target and destroy cancerous tumors while minimizing harmful side effects. This breakthrough, led by researchers from Harvard Medical School and the Massachusetts Institute of Technology (MIT), could revolutionize cancer treatment by offering a safer alternative to traditional therapies.
The study involved implanting mice with cancerous tumors and injecting them with genetically modified CAR-NK (Chimeric Antigen Receptor Natural Killer) cells. Unlike conventional methods, these NK cells are part of the immune system and can kill invaders without needing prior training to recognize specific threats. This makes them a promising candidate for cancer treatment.
Similar to CAR-T cells, which have become widely used in cancer treatments, CAR-NK cells are engineered to specifically target cancer cells. However, one major challenge with CAR-NK cells is their potential rejection by the patient’s immune system. To address this, the Boston-based research team developed a new series of CAR-NK cells that can evade detection by the body’s immune defenses.
The key to this innovation lies in modifying the NK cells to “silence” certain properties that would otherwise trigger an immune response. By doing so, the cells can remain in the body longer and continue fighting cancer. In the experiment, mice that received these modified CAR-NK cells retained the cells in their bodies for three weeks, leading to nearly complete elimination of the cancer. In contrast, mice that received naturally occurring NK cells or standard CAR-NK cells saw those cells deplete within two weeks, allowing the cancer to grow unchecked.
Another advantage of the new CAR-NK cells is their reduced risk of causing cytokine release syndrome (CRS), a severe side effect associated with chemotherapy. The genetic modification required for the new CAR-NK cells involves just one additional step, making it easier to develop ‘off-the-shelf’ versions that can be administered immediately after diagnosis. Traditional CAR-NK and CAR-T cell therapies often take several weeks to prepare due to multiple complex steps.
Jianzhu Chen, senior study author and professor of biology at MIT, emphasized the benefits of this approach. He stated, “This enables us to do one-step engineering of CAR-NK cells that can avoid rejection by host T cells and other immune cells. And, they kill cancer cells better and they’re safer.”
Targeting Lymphoma and Beyond
The study, published in Nature Communications, focused on mice with human-like immune systems that were injected with lymphoma-inducing cells. Lymphoma affects approximately 90,000 Americans each year and leads to around 20,000 deaths annually.
To create CAR-NK cells, doctors typically extract blood from a patient, isolate NK cells, and engineer them to express the chimeric antigen receptor (CAR), which targets proteins found on cancer cells. These cells then replicate over several weeks before being transfused back into the patient.
Researchers discovered that NK cells can evade detection by T cells if the T cells lack surface proteins known as HLA class 1. These proteins usually signal T cells to attack if the immune system cannot recognize the cells. The team engineered the CAR-NK cells to express short interfering RNA that prevents the expression of HLA 1 genes. This modification allowed the cells to remain undetected by the immune system.
Mice that received the modified CAR-NK cells retained the cells in their bodies for three weeks and experienced near-complete remission of their lymphoma. In contrast, mice receiving normal NK cells or CAR-T cells did not show a response, as the cells were filtered out of their bodies after two weeks, allowing the cancer to progress.
Chen suggested that these modified CAR-NK cells could eventually replace CAR-T cell therapy. While CAR-NK cells are already being tested in clinical trials for lymphoma and other cancers, the Boston researchers believe their findings could enhance these studies.
Future Implications and Research Directions
The team is now planning to conduct a clinical trial using their approach and is collaborating with a biotech company to test CAR-NK cells in treating lupus, an autoimmune disorder affecting 1.5 million Americans. Lupus causes the immune system to attack healthy tissues and organs, and this new treatment could offer a more effective and safer option for patients.
As research continues, the potential of CAR-NK cells to transform cancer treatment and autoimmune disease management remains a promising area of exploration. With ongoing advancements, the future of medicine may soon see these innovative therapies become a standard part of care.
