A new combination treatment for cancer that uses immunotherapy, nanoparticles and lasers is generating excitement among researchers. A team from Duke University tested the therapy in a small study and found that it could eliminate cancer, not just where it starts, but also where it spreads.
Checkpoint inhibitors activate immune system response
Some immune cells have a protein on their surface called PD-1. This protein binds to another protein on cancer cells called PD-L1, and this interaction stops the immune system from attacking cancer cells. A form of immunotherapy called a checkpoint inhibitor interferes with this interaction, activating the immune system to attack cancer cells.
Checkpoint inhibitors have had some success in treating cancer, but researchers are continuing to find ways to make them better, including combining them with other experimental therapies.
One such therapy uses heat to kill cancer cells. Raising the temperature of cancer cells can kill the cells directly, but can also improve the effectiveness of cancer drugs and help to trigger an anti-cancer immune response.
Researchers combined immunotherapy and heat therapy
In this study, the researchers developed and tested a treatment called SYMPHONY, which combined heat therapy and checkpoint inhibitors.
In the first step of the treatment, the researchers injected specially designed nanoparticles, tiny structures smaller than a millionth of a centimetre, into the bloodstream. These nanoparticles travelled to the tumour and accumulated. The researchers targeted the tumour with a laser, causing the nanoparticles to warm and raising the temperature at the site to kill cancer cells.
After this, the researchers gave a checkpoint inhibitor to activate the immune system. By involving the immune system, cancer cells could be targeted wherever they are in the body, which is important for treating cancer that has spread.
The researchers found that this innovative two-step approach was more effective than treating cancer with the checkpoint inhibitor alone. The approach eliminated cancer cells at the original tumour site with heat, as well as at distant locations where it had spread, likely because of the increased immune system response. The researchers also found that this treatment provided long-lasting protection against cancer, similar to a vaccine.
Combination approach could treat cancer spread
When cancer spreads, or metastasizes, it becomes much more difficult to treat. In many cases, once cancer has spread, treatment is focused more on maintaining a patient’s quality of life rather than on eliminating the disease. Tackling metastasis is one of the most difficult challenges in cancer research today.
This highly innovative treatment strategy offers a new way to treat cancer metastases that eliminates tumours completely. Checkpoint inhibitors are already approved for some people with cancer and could be made more effective for a longer period of time if combined with the experimental nanoparticle and heat therapy.
This research is just the first study showing that this approach has promise, and it is a long way from being used in the clinic. But this early success is encouraging and provides the basis for larger studies to confirm the results and move the approach forward.
Eileen Hoftyzer, BSc, and Carolyn Goard, PhD