Successful New Breast Cancer Treatment Announced by Revlon/UCLA Women's Cancer Research Program
Researchers at UCLA's Jonsson Comprehensive Cancer Center today (May 17) announced a significant medical breakthrough: positive results of extensive trials of a new breast cancer drug that is the first successful cancer treatment targeted to attack a specific genetic alteration. The treatment is not yet available to the general public.
UCLA's cancer center developed the drug with financial support from the Revlon/UCLA Women's Cancer Research Program and in conjunction with the pharmaceutical company Genentech Inc. of South San Francisco.
The drug, called Herceptin, can be effective for breast cancer patients who have an overabundance in their tumor cells of a gene called HER-2/neu. About 30 percent of women with breast cancer fall into that category.
"Herceptin is the first successful cancer treatment that targets a specific genetic alteration as opposed to using a shotgun approach that kills both diseased and healthy cells," said Dr. Dennis Slamon of UCLA's Jonsson Cancer Center, director of the Revlon/UCLA Women's Cancer Research Program and lead scientist in the discovery research and early development of Herceptin.
"And Herceptin has none of the serious side effects associated with traditional chemotherapy, such as nausea, vomiting, hair loss or significant drops in blood counts," Slamon continued. "A few patients using Herceptin who have used or are using the drug Adriamycin experience cardiac abnormality, but in most cases the situation can be remedied and patients can continue using Herceptin."
Experimental Herceptin treatments were given to women for whom the best available standard chemotherapy was judged to be either a combination of the drugs Adriamycin and Cytoxin or the single drug Taxol.
When taken in combination with the drugs Adriamycin and Cytoxin, Herceptin resulted in a significant response (a 50 percent or greater measurable breast cancer reduction) in 52 percent of patients, as opposed to similar results in just 43 percent of patients who took Adriamycin and Cytoxin alone. So using Herceptin in combination with Adriamycin and Cytoxin was 20 percent more effective than using Adriamycin and Cytoxin alone.
Results were even more impressive among women who took Herceptin in combination with the drug Taxol. While significant response to Taxol alone was only 16 percent, women taking Taxol in combination with Herceptin had significant responses in 42 percent of the cases, representing a 160 percent improvement.
Overall, the Herceptin/chemotherapy combinations caused a significant decrease in measurable breast cancer in 48 percent of patients, whereas only 32 percent experienced significant response with chemotherapy alone. In other words, patients using Herceptin in combination with chemotherapy had a 50 percent better response rate than patients using chemotherapy alone. Moreover, that better response rate was accompanied by a greater than 60 percent increase in duration of the response over what was found in women treated with the chemotherapy alone.
(In a trial being reported separately, 22 percent of patients who took Herceptin alone experienced a 50 percent or greater measurable reduction in breast cancer.)
Results of the Herceptin trials were announced in Los Angeles at the American Association of Clinical Oncology after a 2« -year worldwide study.
Women entering the trial were "randomized" so that approximately half of them received Herceptin combined with the best available chemotherapy and the other half received chemotherapy alone.
"The success of Herceptin opens a new frontier in cancer treatment," Slamon said. "Not only did it exceed our expectations as a drug against breast cancer, but because about 20 percent of women with ovarian cancer overexpress the HER-2/neu gene, we think it may also be effective for women with that disease."
Slamon emphasized that Herceptin does not work for all patients who overexpress the HER-2/neu gene, and that the drug is not yet available to the general public.
"We are working in the lab right now to find out why Herceptin does not help all women who overexpress the HER-2/neu gene," Slamon said.
The HER-2/neu gene is involved in the replication of many types of cells. However, when the gene is present in extra numbers, and as a result is overexpressed in breast or ovarian cancer cells, those cells replicate out of control, causing cancer.
Slamon said he and his colleagues are currently investigating the relationship between the HER-2/neu gene and various other cancers.
HER-2/neu genes produce a specific protein in the cell. That protein is found on the cell surface, where it acts like a tiny antenna, receiving signals from outside of the cell and relaying those signals to the nucleus to tell the cell to split, or replicate.
In a cell that overproduces the HER-2/neu protein, Herceptin binds to the protein "antenna," preventing the cell from receiving and/or transmitting the growth stimulatory signal that would tell it to replicate.
"The next step is to seek the most expeditious FDA approval route for Herceptin, based on the data in our trials," Slamon said. "We're hoping for that approval before the end of this year."