Nanoparticles Designed to Stop Cancer Metastasis

Particles are surrounded by a protective coating to release drugs in the presence of a specific tumor enzyme.

A team of scientists at University of California, San Diego, has developed nanoparticles that release metastasis-prevention drugs in the presence of tumors.

The researchers engineered small, spherical particles with cancer drugs inside. These nanoparticles were surrounded by a protective coating to only release the drugs in the presence of a specific tumor enzyme.

To ensure that these drugs are only released in the presence of tumors, researchers designed the treatment so that the nanoparticles could be broken apart by matrix metalloproteinase (MMPs). MMPs occur in abundance in cancer cells, making them a good indicator of tumor growth. MMPs are also crucial for metastasis, as they rip open cell membranes for cancer cells, so they spread throughout the body.

The nanoparticles are made so that they are also torn apart by MMPs. When the particles are opened, the anti-cancer drug paclitaxel is released.

By coating the spheres with a peptide shell, the protection allows scientists to give patients much higher doses than currently used in cancer clinics. This was tested in mice infected with fibrosarcoma tumors. In mice treated with these nanoparticles, tumor growth was halted by at least two weeks. In those mice treated with MMP resistant nanoparticles, the tumors grew to lethal sizes.

This work expands on work by Nathan Gianneschi, a professor of chemistry at UCSD. Gianneschi says that these findings will help the team broaden their approach, to make these kinds of treatments available for other therapeutic molecules.

"This kind of platform is not specific to paclitaxel. We'll test this in other models -- with other classes of drug and in mice with a cancer that mimics metastatic breast cancer, for example," he said.

In the future, the team is now trying to perfect the shield further, to offer even more protection. This enzyme-directed assembly of particle theranostics (EDAPT) is patent pending.

This study was published in the July 2015 edition of Advanced Materials.