A paper-thin, biodegradable implant is proving an effective way to attack cancer cells without punishing the body with chemotherapy. The implant is a clear, flexible film that can be designed in any shape or size. A key ingredient in the film is chitosan, which is derived from a natural material extracted from algae and the exoskeletons of shellfish.
Researchers at the University of Toronto have developed a way to dissolve a high concentration of various cancer-fighting drugs within the film, which is then applied directly to a site where a tumor has been removed. The drugs, which are loaded into polylactide nanoparticles, are control-released over several weeks as the implant breaks down in the body. “The formulation appears to be quite flexible,” says Micheline Piquette-Miller, an assistant professor of pharmaceutical sciences at the university and codeveloper of the drug-delivery system. “We can incorporate very diverse types of chemicals into it, and that’s what a lot of other systems have had trouble with.”
Piquette-Miller and her team are currently focusing their research on ovarian cancer, which has a high relapse rate and typically requires several rounds of chemotherapy following tumor removal.
Cancer drugs administered orally or intravenously often don’t reach the right organ or region of the body in strong enough doses. By applying a high concentration of cancer-fighting agents directly to a tumor site, the drugs are more likely to kill the target cells.
“We’re also working on an injectable formulation,” says Piquette-Miller, explaining that an implant could be placed within an area of the body without the need for surgery–ideal for treating prostate, breast, and other forms of cancer. “It’s a liquid gel at room temperature, and it forms an implant once it is injected into the body and reaches 37 degrees Celsius,” she says.
For the past three years, the team has been testing the system on different strains of mice to determine the efficacy of certain drug concentrations. Two weeks ago the researchers received funding to carry out a series of toxicity studies on mice before beginning human testing. Christine Allen, codeveloper and University of Toronto chemical engineer, says the film has been designed to be flexible enough that it won’t puncture internal organs. It’s also completely biocompatible. “One of the problems with past systems like this is they’re seen as foreign by the body, and tissue grows around it,” Allen explains. In this situation, called fibrous encapsulation, the surrounding tissue can often prevent proper drug release or keep the drug from reaching the tumor. “We haven’t had this problem,” she says.