Nanoparticle technology has allowed scientists to package an anticancer component of bee venom into a targeted therapy for cancer. Melittin, a host-defense peptide found in bee venom, has long been known to possess antitumor properties, but its use as an anticancer agent has been limited because melittin also attacks healthy cells, particularly red blood cells. However, researchers at Washington University in St. Louis have created melittin-containing nanospheres—which they call nanobees—that can be safely introduced into the bloodstream. The nanoparticle delivery system protects normal cells from the melittin. The anticancer activity of the melittin begins only after the melittin detaches from the nanoparticles in the presence of a tumor. The nanobee approach may thus avoid some of the systemic toxic effects of traditional chemotherapy. So far, the nanobees have been tested only in mice, using breast and skin cancer models. In treated mice, the tumors shrank or stopped growing.

Development of the nanobee system involved scientists from several disciplines and was essentially accidental. Once the scientists found that melittin formed a stable bond with the outer lipid layer of the nanoparticle, they realized they had a potential vehicle for delivering melittin directly to tumors. To get the melittin to detach at a tumor site, they added a ligand that had special affinity for a receptor associated with new blood vessels, which are plentiful around tumors. At tumor sites, the melittin detaches. It therefore does not circulate unattached in the bloodstream.

The researchers used synthetically produced bee venom, not bee venom extracts, to reduce the potential for allergic reactions. Human trials are planned.

The research results were published in the August 10 online issue of the Journal of Clinical Investigation.