The vitamin E analog, alpha-tocopheryloxyacetic acid enhances the anti-tumor activity of trastuzumab against HER2/neu-expressing breast cancer

• Main Authors: Penichet Manuel L, Lu Hailing, Mary Disis L, Gately Stephen, Von-Hoff Daniel, Hurley Laurence H, Bradley-Dunlop Deborah J, Hahn Tobias, Besselsen David G, Cole Brook B, Meeuwsen Tanisha, Walker Edwin, Akporiaye Emmanuel T
• Format: Article
• Language: English
• Published: BMC 2011-11-01
• Series: BMC Cancer
• Online Access: http://www.biomedcentral.com/1471-2407/11/471

<p>Abstract</p> <p>Background</p> <p><it>HER2/neu </it>is an oncogene that facilitates neoplastic transformation due to its ability to transduce growth signals in a ligand-independent manner, is over-expressed in 20-30% of human breast cancers correlating with aggressive disease and has been successfully targeted with trastuzumab (Herceptin^®). Because trastuzumab alone achieves only a 15-30% response rate, it is now commonly combined with conventional chemotherapeutic drugs. While the combination of trastuzumab plus chemotherapy has greatly improved response rates and increased survival, these conventional chemotherapy drugs are frequently associated with gastrointestinal and cardiac toxicity, bone marrow and immune suppression. These drawbacks necessitate the development of new, less toxic drugs that can be combined with trastuzumab. Recently, we reported that orally administered alpha-tocopheryloxyacetic acid (α-TEA), a novel ether derivative of alpha-tocopherol, dramatically suppressed primary tumor growth and reduced the incidence of lung metastases both in a transplanted and a spontaneous mouse model of breast cancer without discernable toxicity.</p> <p>Methods</p> <p>In this study we examined the effect of α-TEA plus HER2/<it>neu</it>-specific antibody treatment on HER2/neu-expressing breast cancer cells <it>in vitro </it>and in a HER2/<it>neu </it>positive human xenograft tumor model <it>in vivo</it>.</p> <p>Results</p> <p>We show <it>in vitro </it>that α-TEA plus anti-HER2/<it>neu </it>antibody has an increased cytotoxic effect against murine mammary tumor cells and human breast cancer cells and that the anti-tumor effect of α-TEA is independent of HER2/<it>neu </it>status. More importantly, in a human breast cancer xenograft model, the combination of α-TEA plus trastuzumab resulted in faster tumor regression and more tumor-free animals than trastuzumab alone.</p> <p>Conclusion</p> <p>Due to the cancer cell selectivity of α-TEA, and because α-TEA kills both HER2/<it>neu </it>positive and HER2/<it>neu </it>negative breast cancer cells, it has the potential to be effective and less toxic than existing chemotherapeutic drugs when used in combination with HER2/<it>neu </it>antibody.</p>