Nano-scale drug delivery for chemotherapy drugs

Bioengineers at Duke University have developed a simple and inexpensive method for loading cancer drugs into nano-scale delivery vehicles which can eliminate tumours in one treatment. 

After 24 hours, cancer cells have taken up the chimeric polypeptide -chemo combination, shown in magenta

Nano-delivery systems have become increasingly attractive to researchers because of their ability to get into tumours efficiently.  Blood vessels supplying tumours are more porous than normal vessels, and nano-drugs can enter tumour cells more easily and accumulate, meaning higher doses of the drugs can be delivered, increasing its cancer-killing abilities while decreasing the side effects associated with systematic chemotherapy.

“When used to deliver anti-cancer medications in our models, the new formulation has a four-fold higher maximum tolerated dose than the same drug by itself, and it induced nearly complete tumour regression after one injection,” said Ashutosh Chilkoti, Theo Pilkington Professor of Biomedical Engineering at Duke’s Pratt School of Engineering.

Bioengineers used Escherichia coli which had been genetically altered to produce a specific artificial polypeptide known as a chimeric polypeptide. When attached to the chimeric polypeptide, the chemotherapy drug – in this case doxorubicin which is commonly used to treat cancers of the blood, breast ovaries and other organs – dissolves in water consistently and reliably in a size of 50 nanometers, which makes them ideal for cancer therapy.  Once the drug has been delivered, the vehicle breaks down into harmless by-products, reducing toxicity to the recipient.

Chilkoti’s results – published in Nature Materials – showed mice treated with doxorubicin alone had an average tumour size 25 times greater than those treated with the new formulation, and survived for 27 days, compared to 66 days for mice receiving the new treatment.

 “Unlike other approaches, we can produce large quantities simply and inexpensively, we believe the new method theoretically could be used to improve the effectiveness of other existing cancer drugs,” Chilkoti said.

The researchers plan to test the new combinations on different types of cancer, as well as tumours growing in different organs.  They will also try combining the chimeric polypeptides with other insoluble drugs to test their effectiveness against tumours.