Shrimp-shell nanoparticle could cut cancer drug side effects and improve durability, mouse study shows

In the hunt for safer and more effective delivery methods for cancer drugs, scientists are taking a cue from the natural armor that surrounds shrimp, insects and other chitinous critters. 

Researchers at the University of Washington say they've derived a nanoparticle from those exoskeletons that can help cancer drugs remain in the body longer and potentially cut down on side effects, too.

Chitin is an organic polymer that makes up the shells of insects and crustaceans, and because it occurs naturally, chitin-derived carriers could offer a safer alternative to the delivery systems currently used in cancer therapy, many of which come with toxicity risks, lead researcher Miqin Zhang said in a release. 

In a mouse study published in Materials Today, the UW team paired its nanoparticles—made of chitosan, created when chitin is treated with an alkaline substance—with Bristol Myers Squibb's cancer chemotherapy Taxol, also known as paclitaxel.

The drug carriers begin their lives as longer strands of chitosan, which are designed to break down into nanoparticles once exposed to serum in the lab or blood protein in the body. 

When injected into mice, the nanofibers quickly dispersed into nanoparticles, able to move freely through the blood, enter organs and reach tumor sites, the team said. 

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In rodents, the Taxol-paired nanoparticles charted 90% inhibition of breast tumor growth—a dramatic jump from the 66% displayed by standard Taxol, the team said.

The nanoparticles also curbed melanoma tumor growth in mice by up to 75%, and in a separate mouse experiment, prevented the spread of breast cancer to other parts of the body—something free-floating Taxol, delivered via injection in a clinical solution, can't manage, they said.

What's more, the chitinous nanoparticles helped Taxol stick around in the blood much longer than the standard formulation did. The half-life of Taxol delivered with the team's nanoparticles was nearly 25 hours versus the less-than-two-hour half-life of Taxol proper. 

Plus, in a cell culture study, a "majority" of mouse breast cancer cells displayed signs of cell death 48 hours after treatment, suggesting the nanoparticle carriers work on par with standard Taxol, the team said. 

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No side effects from the carriers were observed. This suggests the nanoparticles could be less toxic—and trigger fewer side effects than the current formulation does, the team said.

"Many drug delivery systems used today for anti-cancer drugs come with toxic side effects and don’t protect the drug for very long in the patient’s body," Zhang said in a release. "The small chitosan-based nanocarrier, made in situ, with unique biocompatibility and biodegradability, offers a new strategy for anti-cancer drug delivery and has great potential for rapid translation to the clinic.”