MIT’s Robert Langer, a professor of both chemical and biological engineering, and a Harvard counterpart lead this new, $20 million enterprise, which is administered through MIT’s cancer center. And its task of applying nanotechnologies to cancer means using the very small to accomplish things that can be done no other way.
How small is very small? A nanometer’s a billionth of a meter—about one ten-thousandth the width of a human hair.
There are many reasons why anti-cancer agents at that scale are useful. For example, when you’re trying to target something as tiny and stoutly defended (by its outer membrane) as a cell, those are the length scales you need. As Langer notes, “anything bigger than about 150 nanometers can’t penetrate a cell.”
The concept behind Langer’s work on what he terms nanospheres is to turn them, in effect, into battlefield medics. Made of carefully chosen polymers, and infused with the medicine of choice, they would roam freely in the bloodstream. “You’ll also want them to be taken up by specific cells, like tumor cells,” says the scientist, a member of the MIT cancer center and the Harvard-MIT Division of Health Sciences and Technology (HST). Langer and his co-leader on the project, Omid Farokhzad of HST and Brigham & Women’s Hospital, are working on nanospheres with a homing molecule specific for prostate tumors.
“We’re looking at prostate cancer,” explains Langer, “because we already have good targeting entities for that tumor.” But the approach has potential against virtually any type of cancer.
Langer, an Institute Professor at MIT and holder of more than 500 patents, brings unique credentials to the job of making this new approach work. He earned his spurs in medically related engineering while working with a physician-scientist on the process of blood vessel formation, a phenomenon called angiogenesis. That work helped set the stage for new drugs based on choking off a tumor’s blood supply. He has similarly shown that polymers in the form of microspheres — which are, on average, some 1,000 times bigger than his nanospheres — can be great carriers for drugs when injected at the site of a tumor.
In the context of cancer treatments relying on what’s called small interfering RNA (siRNA), a “designed” form of small RNA, Langer’s working on a key facet of the problem: developing nano-scale polymer ferries that can protect the fragile agent from being broken down in the body. His associate Sangeeta Bhatia, meanwhile, is collaborating with Sharp on related issues involving siRNAbearing particles.
Bhatia has a doctorate from HST, and now is a faculty member in that division as well as in electrical engineering and computer science at MIT. The researcher works with particles made of various materials, including gold and iron oxides. Why these choices? Both are approved for patient use, she notes, “and we’re really interested in making formulations that can be applied clinically.”
Bhatia and her co-workers, using an approach akin to but not the same as Langer’s, have already succeeded in targeting cancerous tissues with their nanoparticles. “In a mouse model of cancer,” she notes, “we’ve shown we can make these particles home to tumor tissues.”
Next up: demonstrating that siRNA-bearing nanoparticles can actually slow or shrink tumors. Those experiments start later this year.