An interdisciplinary group of scientists has successfully destroyed tumor cells in mice by using nano-sized copper compounds alongside immunotherapy. Importantly, the tumors did not return after the treatment ceased.
According to the World Health Organization, cancer is the second leading cause of death worldwide — in 2018, it was responsible for approximately 9.6 million deaths.
Reducing behavioral or dietary risks associated with cancer is an important way of lowering the total number of cancer deaths; however, finding effective treatments is also crucial.
Doctors usually treat cancer with chemotherapy, but this often has significant side effects. For example, some chemotherapy medication can wipe out a person's white blood cells, leaving their immune system compromised and open to infection.
Although chemotherapy treatment can be successful, there is always a risk that a person's cancer might return.
Recent advances in cancer treatment include immunotherapy, which involves using a person's immune system to fight cancer cells. However, this does not always work or may only slow down the growth of cancer, so it cannot yet replace chemotherapy.
In the new study on mice, the scientists combined immunotherapy with copper-based nanoparticles. This combination treatment destroyed the tumor cells without the use of chemotherapy. Most importantly, however, the tumor cells did not return after treatment ceased.
The team of scientists — from KU Leuven in Belgium, the University of Bremen, the Leibniz Institute of Materials Engineering both in Germany, and the University of Ioannina in Greece — found that tumors in mice are sensitive to copper oxide nanoparticles.
Typically, these nanoparticles are toxic when inside an organism. The scientists found that by using iron oxide to create the nanoparticles, they could control which cells the nanoparticles destroyed, leaving healthy cells unaffected. They recently published their findings in the journal Angewandte Chemie International Edition.
Prof. Stefaan Soenen and Dr. Bella B. Manshian from the Department of Imaging and Pathology at KU Leuven worked together on the study. They explain how "any material that you create at a nanoscale has slightly different characteristics than its normal-sized counterpart." They continue:
"If we ingest metal oxides in large quantities, they can be dangerous, but at a nanoscale and at controlled, safe concentrations, they can actually be beneficial."
The scientists began by using only the nanoparticles to target the tumor cells. As expected, the cancer returned. However, the team discovered that the nanoparticles could work in conjunction with the mice's immune systems.
"We noticed that the copper compounds not only could kill the tumor cells directly, they also could assist those cells in the immune system that fight foreign substances, like tumors," said Dr. Manshian.
Blocking cancer's return
When the scientists combined the nanoparticles with immunotherapy, the tumor cells died and did not return.
To confirm the results, the scientists injected the mice with new tumor cells. The mice's immune systems immediately destroyed the new tumor cells.
"As far as I'm aware, this is the first time that metal oxides [have been used] to efficiently fight cancer cells with long lasting immune effects in live models," Prof. Soenen says. "As a next step, we want to create other metal nanoparticles and identify which particles affect which types of cancer. This should result in a comprehensive database."
Results derived from animal testing do not necessarily work when it comes to humans, and to take the research further, the team intends to test the treatment on human tumor cells. If that is successful, they will conduct a clinical trial.
However, according to Prof. Soenen, there are still several hurdles along the way:
"Nanomedicine is on the rise in the United States and Asia, but Europe is lagging behind. It's a challenge to advance in this field because doctors and engineers often speak a different language. We need more interdisciplinary collaboration so that we can understand each other better and build upon each other's knowledge."