Scientists Devise “Nanospheres” to Safely Deliver High-Dose Chemotherapy

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Newman_150715_3One of the primary difficulties concerning cancer treatment is finding a way to prevent highly toxic chemo medication from affecting non-cancerous tissue.

According to a recent report published in the journal Advanced Materials, researchers believe they have found a possible way to create a “carrier” that prevents the drugs from being released until it comes in contact with cancer-specific enzymes.

The potential for a tumor to metastasize—to spread to other areas—is the main hallmark of cancer. This is carried out with the aid of a class of enzymes called matrix metalloproteinases (MMPs)—this is what the cancerous cells actively produce. MMPs dissolve membranes in the body, which allow cancer cells to be released and spread.

Cassandra Callmann, the first author of the study, has devised a “nanosphere” made of peptides that she filled with the anti-cancer drug paclitaxel. With an explanation not out of place in a science fiction story, Callmann describes how the MMPs eat through the shell and release the drug near the site of the tumor. The shell fragments then form a “net” to keep the drug’s molecules in place.

During laboratory tests with mice, Callmann and her fellow researchers were able to use the nanospheres to safely administer doses of paclitaxel that were 16 times higher than was possible with the methods currently in use for human patients. In one series of tests, tumor growth was halted for two weeks in mice given the nanosphere-delivered drugs. The control group—given saline or nanospheres resistant to MMPs—had their tumors grow to a lethal size in the same period.

The nanosphere delivery method is compatible with more drugs than just paclitaxel, but since it is based on chemical bonds, further research needs to be done before it can be broadened. The design of the nanosphere itself will be further refined to better protect non-targeted organs, such as the liver or kidneys.

Other research groups have looked into similar applications of nanospheres to enable “smart drug” delivery systems. In 2014, researchers at Boston College developed a nanosphere made of a mix of organic and metallic materials to deliver breast cancer treatments.

Sources for Today’s Article:

Hayward, E., “‘Smart’ Drug Delivery Could Aid Cancer Fight,” The Boston College Chronicle web site, May 8, 2014;–drug-delivery-could-aid-cancer-fight.html.

“Nanospheres shield chemo drugs, safely release high doses in response to tumor secretions,” Medical News Today web site, July 15, 2015;