Between 1970 and 1994, well over 1 million women died as a consequence of breast cancer in the US alone, representing the third most common cause of cancer-related death across both sexes. The search for new anti-cancer drugs remains intense and in fact almost 25% of all drugs in development or on the market are intended for the treatment of cancer, 12% of which are specifically for breast cancer. The majority of molecules (70%) in development or on the market for breast cancer are cytostatic in nature. Cytostatic approaches usually include the use of hormonal and/or chemotherapies. Doxorubicin is one of the most frequently used examples of the latter however it is associated with well characterized toxicity. This not only presents quality of life issues but also means that dose escalation is often not possible in the event that drug resistance develops. There is a considerable need therefore to develop new chemotherapies that cause less severe systemic toxicity. This is reflected in the high level of activity surrounding the development of next-generation chemotherapies. Targeting chemotherapies to tumor cells through the use of antibodies represents one approach to reducing systemic toxicity (Click here for our recent dossier "Targeted immunotherapy as an evolving strategy for the treatment of primary, residual and metastatic cancer"). An equally promising area of drug development, virosome technology, has now been harnessed to improve tumor targeting. Virosomes are spherical, unilamellar lipid bilayer into which are inserted purified viral (for example influenza) envelope glycoproteins. These viral protein are responsible for virosome:host cell fusion and consequent penetration. Virosomes can be loaded with genes, oligonucleotides or chemotherapies. Swiss researchers have made exciting advances in this technology, conjugating the Fab' fragment of anti-NEU monoclonal antibody to virosomes loaded with doxorubicin. This combines effective targeting of breast cancer cells with efficient virosome mediated cell penetration. Unsurprisingly, this resulted in the inhibition of tumor formation at a tumor load representing metastatic spread. This approach is highly flexible and can be used to target a wide variety of therapeutic agents to a range of different tumors through the selection of appropriate antibody fragments. Collaboration with this group is likely to help drive forward a ground-breaking approach to cancer.

Targeting her-2/neu with antirat Neu virosomes for cancer therapy