Nanoparticle drug delivery systems are a hot area in medical research at the moment. The ability to engineer particles that can enter a human body and transport a drug directly to a targeted cell is revolutionizing how medicine is delivered. A team of researchers from the University of Illinois has now created a new nanoparticle therapy that can target and destroy cancer stem cells to stop the disease returning.

The fear of relapse is one that constantly haunts cancer patients after any initial treatment has moved the disease into remission, but understanding how and why cancer returns eluded scientists for many years. In the mid-1990s, researcher John Dick first identified cancer stem cells, upending the field of cancer research and pointing to an entirely new area of study for scientists.

The discovery was that some cancers can be generated by these cancer stem cells (CSCs), and many existing treatments, while effective in destroying fast-growing cancer cells, completely miss these CSCs.

"It is critical to administer treatments for already-developed tumors; however, long-term survival and not allowing it to come back are equally important," says lead on the new study, Dipanjan Pan. "We want to destroy the cells that are hidden in the tissue and cause the cancer to come back or spread to other parts of the body."

The new research focused on breast cancer stem cells and identified a variation in a protein called CD44 that only appears on the surface of those cells. The team then designed a nanoparticle that binds to that specific protein.

"I call them 'GPS-enabled nanoparticles,' because they seek out only the cells that have cancer stem cell properties," says Pan. "Then they latch onto the cells and deliver the drug."

Inside these nanoparticles is a drug called niclosamide, an already approved drug used for tapeworm infections. Previous research by the same team revealed the drug is effective in disabling the pathways that cause cancer stem cells to grow.

Early studies on human cell cultures in vitro and in live mice showed the team's nanoparticles were effective in both targeting the specific cancer stem cells and decreasing their growth into cancer cells.

The most interesting aspect of this particular research is the way it is concentrating on using preexisting, and cheap, drugs in combination with a type of nanoparticle that is easy to manufacture. This means the treatment will not only ultimately be relatively inexpensive, but it should be able to move through approval processes more rapidly than if it made use of an entirely new drug.

"We purposely used an extremely inexpensive drug," says Pan. "It's generic and we can mass produce it on a very large scale. The nanoparticles are a polymer that we can make on a large scale – it's highly defined and consistent, so we know exactly what we are delivering. The rest of the process is just self-assembly."

The treatment is currently being tested on larger animal models in the hopes it can be moved to human clinical trials in the near future.

The study was published in the journal Molecular Cancer Therapeutics.