Combining GlaxoSmithKline Plc’s Tykerb drug with Roche Holding AG’s Herceptin to treat breast cancer was almost twice as effective as single-drug therapy, according to researchers in a 23-country clinical trial.
The rate of eradicating residual invasive breast cancer in patients given the combination therapy was 51 percent compared with 30 percent in patients given Herceptin alone and 25 percent for those receiving Tykerb alone, researchers led by Jose Baselga, associate director at the Massachusetts General Hospital Cancer Center in Boston, said in a study published today in The Lancet journal.
Tykerb, known scientifically as lapatinib, is approved in 107 countries to treat metastatic, or late-stage, breast cancer. The drug is being studied by London-based Glaxo in sequence and in combination with Herceptin to treat early-stage cancer. Herceptin, also known as trastuzumab, is the first medicine approved to directly target HER2, a protein that tells malignant cells to grow and spread throughout the body. About 25 percent of breast cancers are driven by HER2.
“Our study provides proof of concept that dual HER2 blockade is better than single-agent anti-HER2 therapy,” the researchers said in the article.
The study followed 455 women with the HER2 protein who took the combination or single therapies over a six-week period, followed by 12 weeks of standard paclitaxel treatment, surgery and the same drug treatment for one year.
A side effect of Tykerb is diarrhea, which occurred in 21 percent of participants using the combination therapy, compared with 2 percent taking Herceptin alone.
The trial, funded by Glaxo, is “a model for future research and clinical trial design” as treatment in the first phase was given without chemotherapy, allowing tumor response to be assessed without possible effects from the toxic therapy, Michael Gnant and Guenther G. Steger, professors at the Medical University of Vienna, said in a commentary published with the Lancet article.
More research is needed to explore how long patients should receive the targeted therapies to avoid overtreatment, they wrote.
In a separate study published in The Lancet Oncology journal today, German researchers compared patients receiving chemotherapy and Tykerb or Herceptin and found Herceptin to be more effective. Among those taking the Roche drug, 30 percent showed no signs of residual invasive breast cancer following the treatment, compared with 23 percent of patients who received Tykerb, according to the researchers.