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Nanotechnology therapies for cancer progress, block metastasis

Nanotech approaches to cancer therapies continue to show great promise, in large part thanks to wise investment of government funds in basic research. Brandon Keim briefly describes why in a report on the Wired Science blog “Cancer Nanotech: Government Spending Done Right“:

The [National Cancer Institute] poured money into cancer nanotech training and research. At the time, experiments were largely restricted to animals; as of today, at least 48 clinical trials are ongoing, many already in Phase II.

…”The field has been quietly progressing,” said David Cheresh, a University of California, San Diego pathologist … “What happened is that the National Cancer Institute supported this area. They assembled teams at various universities, including my own. That money directly allowed us to do this work [see below].”

Such basic research, said Cheresh, “is not something that industry would necessarily do. They’re not going to support the kind of research that the government would for bringing this to fruition. But they’ll capitalize on the discoveries we make. Those will be taken into the private sector, because we do discovery but aren’t in a position to do a scale-up and the pre-clinical studies. That has to come from the private sector.”

One very recent example of the potential of nanotechnology for cancer therapy is the topic of another article by Keim. In experiments in mice, chemotherapy drugs encapsulated in nanoparticles targeted to the blood vessels that supply nutrients to tumor cells prevented the usually fatal spread of the cancer to additional sites. From “Drug-Infused Nanoparticles Stop Cancer From Spreading“:

By using tumor-targeting nanoparticles filled with chemotherapy drugs, scientists kept kidney and pancreas cancers from spreading through the bodies of mice.

In an experiment described today in the Proceedings of the National Academy of Sciences [abstract], researchers led by University of California, San Diego pathologist David Cheresh designed nanoparticles that selectively attached to a protein found on the surface of blood vessels that supply tumors with nutrients and oxygen.

The particles were loaded with doxorubicin, an effective but highly toxic anti-cancer drug with side effects ranging from white cell destruction to fatal heart disease. By targeting blood vessel cells, the researchers needed just one-fifteenth the amount used in a traditional, system-flooding dose.

…Such findings aren’t unique in the fast-growing field of cancer nanotech, but the researchers found something new: Although their nanoparticles didn’t affect the original tumor, they did stop the cancers from spreading through the mice. That process is known as metastasis — a word synonymous, for anyone who has experience with cancer, with doom.

…”Those trials have begun or are in the process of being finalized,” [Cheresh] said. “The day isn’t too far off.”

A press release from the University of California – San Diego, via AAAS EurekAlert, provides the additional information that the nanoparticles used were “of 100 nanometers [diameter], made of various lipid-based polymers”.

Additional coverage of this research in Discover magazine elicited a comment from someone presumably associated with the drug delivery company pSivida about a nanostructured silicon product for pancreatic cancer that is already in phase IIb clinical trials in humans.

There is also another nano-structured product that is in development for pancreatic cancer called BrachySil. This is nano-structured silicon, doped with P32 that is injected directly into the pancreas. On July 7 it was announced that a Phase IIb clinical trial in humans started in the UK at Guy’s and St. Thomas’ NHS Foundation Trust in London and University Hospital in Birmingham. In the Phase IIa trials completed last year (and the data presented at the ASCO-GI meeting in January) BrachySil in combination with standard chemotherapy (gemcitabine) was well tolerated with no clinical significant adverse events related to the device. Data showed disease control in 82% of patients and an overall median survival of 309 days.

This research from UC San Diego is the second example we’ve seen in less than two weeks of using nanoparticles to enable an otherwise-too-toxic drug to attack the blood vessels supporting a cancer (see Nanodot July 3).
—Jim

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