Among women with HER2-positive advanced breast cancer who have been previously treated with Herceptin® (trastuzumab), the combination of Tykerb® (lapatinib) and Herceptin improves progression-free survival, and possibly overall survival, compared with Tykerb alone. These findings were recently presented at the 2008 annual meeting of the American Society of Clinical Oncology.
The HER2 pathway is a biological pathway within cells that is involved in cellular replication and growth. Approximately 25–30% of breast cancers overexpress the HER2 protein on the surface of the cell; these cancers are referred to as HER2-positive breast cancers.
Treatment options for HER2-positive breast cancer include Herceptin and Tykerb. Herceptin is a monoclonal antibody that targets the HER2 protein. The binding of Herceptin to HER2 prevents or reduces replication of cancer cells. Tykerb is also targeted against the HER2 protein and has produced promising results in women with metastatic or refractory breast cancer. Targeted therapies, such as Herceptin and Tykerb, are anticancer drugs that are designed to treat cancer cells while minimizing damage to normal, healthy cells.
In this recent study, researchers sought to determine whether the combination of Tykerb and Herceptin could improve outcomes compared with Tykerb alone in the treatment of HER2-positive breast cancer that had progressed on prior Herceptin therapy. This Phase III clinical trial involved 296 patients with HER2-positive advanced breast cancer. Nearly half of all patients had hormone-positive breast cancer. Participants received Tykerb plus Herceptin or Tykerb alone.
- Overall, 25% of patients experienced a partial or complete disappearance of their cancer following treatment with Tykerb/Herceptin compared with12% for patients treated with Tykerb-alone.
- 45% of patients treated with Tykerb/Herceptin survived greater than one year compared with 36% of patients treated with Tykerb alone.
- The median overall survival was nearly 52 weeks for the Tykerb/Herceptin group compared with 39 weeks for the Tykerb-alone group.
- Side effects were similar between the two groups (with the exception of diarrhea, which occurred in 60% of patients treated with combination therapy versus 48% for those treated with Tykerb alone).
The researchers concluded that the addition of Herceptin to Tykerb significantly improves progression-free survival and overall response compared with Tykerb alone in patients with HER2-positive advanced breast cancer who have been previously treated with Herceptin. These patients may wish to discuss with their physician their risks and benefits of treatment with Tykerb and Herceptin.
Reference: O’Shaughnessy J, Blackwell KL, Burstein H, et al. A randomized study of lapatinib alone or in combination with trastuzumab in heavily pretreated HER2+ metastatic breast cancer progressing on trastuzumab therapy. Program and abstracts of the 44th American Society of Clinical Oncology Annual Meeting; May 30 – June 3, 2008; Chicago, Illinois. Abstract 1015.
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