Lab Chat: The leaky blood vessels that change how nano-drugs treat cancer
Nanotherapeutics — the use of tiny particles to deliver drugs to hard-to-reach parts of the body — have been approved to treat a few different types of cancer. Now, investigators have found a way to figure out which tumors will actually respond to drugs sent by way of nanoparticles. It has to do with how “leaky” a tumor is, meaning how likely the drugs are to actually penetrate the cancer cells. I chatted with lead researcher Omid Farokhzad of Harvard — who has been involved with several startups that work on nanotherapeutics — about the findings, published in Science Translational Medicine.
Explain this leakiness in tumor cells to me.
The epithelial cells, which line blood vessels, form very, very tight contact with neighboring cells. That’s equivalent to the piping in your house, in that these cells form a tight barrier that doesn’t leak things out, like water can flow through pipes without leaking into the walls.
And how do you think that affects how well nanotherapeutics work?
As cancer grows, it encourages new blood vessels to form, and they’re forming so rapidly that they don’t have time to form these tight junctions. Cancer makes the blood cells intentionally leaky so tumors can get more nutrients from blood cells as they go by. But some cancer patients are more leaky than others. In the patients who don’t have leaky blood vessels, giving them nanoparticles isn’t helpful [because the particles can't penetrate to the tumor].
How have you figured out how to predict which tumors will respond?
We tried to deliver an imaging nanoparticle before a drug nanoparticle. And what the study shows is when the imaging nanoparticle is able to accumulate in tumors at a high level, that tumor will respond really well to a therapeutic nanoparticle.