Nanoparticle Delivers Cancer Drugs to Tumor Blood Vessels

In a set of studies in mice bearing human tumors, nanoparticles designed to bind to a protein called P-selectin successfully delivered both chemotherapy drugs and targeted therapies to tumor blood vessels. Targeting the blood vessels improved the delivery of drugs to tumor tissue, causing the tumors to shrink and improving how long the mice lived.

A tumor’s blood vessels can serve as a barrier to engineered drug-delivery systems like nanoparticles, which may not be able to cross the blood vessel wall. However, the same blood vessels may express proteins—such as P-selectin—that researchers can potentially exploit, by engineering their nanoparticles to recognize and latch onto those proteins, which enables them to reach the tumor.

What makes P-selectin different from other nanoparticle targets, the research team that led the study showed, is that it can be “turned on” in the blood vessels of tumors that do not normally express it by exposing the tumors to certain stressful conditions—in these experiments, a low dose of focused radiation.
This ability to trigger the expression of P-selectin in a tumor that normally lacks the protein, they wrote, suggests that the nanoparticle may be useful against a wide range of cancer types.
The study results were published June 29 in Science Translational Medicine.

Turning on the Target

Blood vessels in some tumors naturally express P-selectin on their surfaces, providing a target for nanoparticles. In the study, a research team led by Daniel Heller, Ph.D., of Memorial Sloan Kettering Cancer Center, engineered drug-carrying nanoparticles made of a sugar-based compound called fucoidan, which is derived from algae and binds to P-selectin.

Read the article here:  http://www.cancer.gov/news-events/cancer-currents-blog/2016/nanoparticle-tumor-vessels