Robert Langer, a chemical engineer at MIT, says that tissue growth can affect how implants deliver drugs, although most systems can handle small amounts of encapsulation. "If [the University of Toronto system] doesn't have any fibrous encapsulation, that would be an advance," he says.

Various polymer systems have been developed for the localized delivery of anticancer drugs, but the University of Toronto film is the first formulation to physically cross-link chitosan--widely used as a wound dressing and in artificial skin--with naturally occurring phospholipids. "Chitosan based polymer blends are useful for controlled drug delivery because they degrade uniformly into non-toxic molecules that are non-mutagenic, non-cytotoxic and non-inflammatory," according to patent documents describing Allen and Piquette-Miller's approach.

Marcel Bally, a senior scientist with the department of advanced therapeutics at the British Columbia Cancer Agency, says the chitosan-based film has the potential to be translated rapidly into clinical use. "It's novel and very practical," says Bally. "What I think is really exciting about this technology is the idea that they're developing a drug-delivery system that's designed for multiple drugs, and there's really not a lot of people doing that right now." He says drug combinations are proving much more effective at battling cancer, so the ability to deliver such anticancer cocktails locally is key. "I think that's where drug-delivery systems will play a huge role in the future."