In nearly one-third of breast cancer cases, a gene encoding a protein called HER2 runs amok. The resulting oversupply of HER2 makes the cancer more aggressive and prone to spread.
Scientists created a stir in 1998 when they reported preliminary findings that the drug trastuzumab, a bioengineered antibody, could prolong survival in some breast cancer patients by neutralizing excess HER2. Details of that study, now published in the March 15 New England Journal of Medicine, have rekindled the optimism sparked by the earlier report.
The drug--called Herceptin by its maker, Genentech in South San Francisco, Calif.--quells HER2 by binding to it. Physician Dennis J. Slamon of the University of California, Los Angeles School of Medicine and his colleagues targeted HER2 because it's suspected of contributing to cell proliferation.