Polymer Implant Trains Immune Cells To Find and Destroy Tumors

Researchers at Harvard have developed a polymer immunotherapy implant that trains the immune system to become cancer soldiers that seek out and destroy tumors inside the body.

Up until now, many immunotherapy treatments involved chemicals and drugs designed to coax immune cells into attacking tumors. However, these methods were only about 60 percent effective in clinical trials. This new polymer implant does all of the work inside the body, and has increased the survival rate of mice with a deadly melanoma from 0 to 90 percent in past studies.

First, it attracts dendritic cells by releasing a kind of chemical signal called a cytokine. Once the cells are there, they take up temporary residence inside spongelike holes within the polymer, allowing time for the cells to become highly active.

The polymer carries two signals that serve to activate dendritic cells. In addition to displaying cancer-specific antigens to train the dendritic cells, it is also covered with fragments of DNA, the sequence of which is typical of bacteria. When cells grab on to these fragments, they become highly activated. "This makes the cells think they're in the midst of infection," Mooney explains. "Frequently, the things you can do to cells are transient—especially in cancer, where tumors prevent the immune system from generating a strong response." This extra irritant was necessary to generate a strong response, the Harvard researchers found.

A lot of questions about the effectiveness of this approach in humans have yet to be answered, but if all goes well the hope is that polymer implants could be not only helpful with cancer patients, but also with those afflicted with immune disorders. [Technology Review]