According to a press release published by GlaxoSmithKline, the addition of the investigative agent Tykerb® (lapatinib) to the chemotherapy agent Xeloda® (capecitabine) slows cancer progression in some patients with advanced breast cancer that has stopped responding to standard therapies.
Breast cancer claims the lives of approximately 40,000 women annually in the U.S. alone. Metastatic breast cancer refers to cancer that has spread from the breast to distant sites in the body. Refractory breast cancer refers to cancer that has stopped responding to standard therapies.
Since long-term survival for patients with metastatic or refractory breast cancer is not favorable, research continues to evaluate ways to improve survival while maintaining quality of life for these patients.
The epidermal growth factor pathway is a biologic pathway that is involved in the replication and growth of cells. However, when there is a mutation (alteration) within this pathway, it can contribute to the growth and spread of cancer cells. Therefore, the epidermal growth factor pathway has been a focus of targeted therapy. The goal of such therapy is to reduce or prevent cancer spread.
There are several sites within the pathway that can be targeted to control the spread of cancer. Researchers are now beginning to target more than one site within the pathway in order to reduce its activity and ultimately prevent cancer from spreading.
Herceptin® (trastuzumab) is a targeted therapy aimed at the epidermal growth factor pathway; it is approved for initial treatment of metastatic breast cancer in combination with the chemotherapy agent Taxol® (paclitaxel); this combination is approved for metastatic breast cancer that overexpresses human epidermal growth factor 2 (HER-2), a protein of the epidermal growth factor pathway. It is also approved as a single agent for the treatment metastatic breast cancer that overexpresses HER-2 and has stopped responding to prior therapies. Patients who stop responding to Herceptin® and chemotherapy have limited treatment options.
Tykerb is an agent that has recently completed the last phase of clinical trials prior to FDA review. Tykerb is targeted against two different sites within the epidermal growth factor pathway.
Researchers recently stopped enrolment in a clinical trial evaluating Tykerb due to positive results. The trial directly compared the treatment combination of Tykerb plus the chemotherapy agent Xeloda to Xeloda alone in the treatment of advanced breast cancer. Patients in this trial had metastatic breast cancer and had stopped responding to standard therapies, including Herceptin. These breast cancers overexpressed HER-2.
- An interim analysis including 321 women revealed that the addition of Tykerb to Xeloda slowed cancer progression by at least 50% compared to Xeloda alone.
- The most common side effects of treatment including Tykerb plus Xeloda were nausea and diarrhea.
An Independent Data Monitoring Committee (IDMC) unanimously recommended halting enrolment in this trial due to these results. Patients already involved in the trial who had received Xeloda alone can choose to switch to the treatment combination of Tykerb plus Xeloda if they wish. Filing to the Food and Drug Administration for Tykerb is planned for the second half of 2006.
Reference: GlaxoSmithKline. GlaxoSmithKline receives positive data and halts enrolment in Phase III trial of Tykerb® (Lapatinib) in advanced breast cancer. Available at: www.gsk.com. Accessed April 2006.
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