The super-small objects known as nanoparticles are playing a big role in combating cancer. They’ve been used to deliver cancer-fighting drugs, to glow in the body to indicate chemotherapy’s efficacy; and to bring powerful alpha particles directly to tumors. Now, researchers at the Mayo clinic have enlisted the petite powerhouses in a new way that helps them recruit the body’s immune system into fighting tumors while also teaching it to be on the lookout for cancer’s return any time in the future.
Along with the use of nanoparticles, one of the more promising developments in treating cancer of late is the use of the body’s own immune system to destroy tumors. The Mayo Clinic technique combines both approaches.
First, a nanoparticle is coated with antibodies that recognize a protein known as HER2. HER2 is found in 40 percent of all breast cancers, and tumors containing the protein tend to grow and spread aggressively. These antibodies help the nanoparticles latch onto the tumor. Then two other molecules attached to to the nanoparticle call in the troops: “clean-up cells” known as macrophages and phagocytes. Basically, the nanoparticle acts like a beacon on the tumor, guiding in the body’s immune system.
But that’s just the first step in the complex mobilization. Once the macrophages and phagocytes arrive on site, they not only set to devouring the cancer cells, but they deliver information to the immune system’s T-cells, which then arrive to destroy any remaining cells. Even more significantly, the T-cells retain a memory of the cancer they’ve battled so that if the same type of tumors return, they can recognize and destroy them, working like a cancer vaccine.
In mice studies, the animals treated with the nanoparticles had a 70-80 percent reduction in tumor size and the rodents showed resistance to growing new tumors even when cancerous cells were introduced into their systems a month later.
The idea of using T-cells to combat cancer is gaining steady traction in the world of oncology, but the technique that employs them – known as adoptive immunotherapy – requires the cells to be removed, modified and returned to the body. The Mayo Clinic method bypasses this step by getting the T-cells to do what they need while still inside the body.
“Our study represents a novel concept of designing nanomedicine that can actively interact with the immune cells in our body and modulate their functions to treat human diseases,” says Betty Y.S. Kim, principal investigator, and a neurosurgeon and neuroscientist who specializes in brain tumors at Mayo Clinic’s Florida campus. “It builds on recent developments in cancer immunotherapy, which have been successful in treating some types of tumors; however, most immunotherapy developed so far does not harness the power of the entire immune system. We’ve developed a new platform that reaches tumor cells and also recruits abundant clean-up cells for a fully potent immune response.”
While this particular study focused on breast cancer, Kim is confident that it can be expanded to combat other tumors. The next step for the researchers is to investigate the potential of the nanoparticles to keep tumors from spreading throughout the body through metastasis.
“In this proof-of-concept study, we were astounded to find that the animals treated with these nanoparticles showed a lasting anti-cancer effect … (with) our custom-designed nanomaterials … prompting the body to create its own memory system to minimize tumor recurrence,” said Kim. “These nanomedicines can be expanded to target different types of cancer and other human diseases, including neurovascular and neurodegenerative disorders.”