Among women with HER2-positive, metastatic breast cancer that has progressed during treatment with Herceptin® (trastuzumab), the combination of Tykerb® (lapatinib) and Herceptin appears to be more effective than Tykerb alone. These results were published in the Journal of Clinical Oncology and were previously presented at the 2009 San Antonio Breast Cancer Symposium.
Approximately 20-25% of breast cancers overexpress (make too much of) a protein known as HER2. Overexpression of this protein leads to increased growth of cancer cells. Fortunately, the development of drugs that specifically target HER2-positive cells has improved outcomes among women with HER2-positive breast cancer. These drugs include Herceptin and Tykerb.
To explore the use of these drugs after initial treatment with Herceptin, researchers conducted a study among 296 women with HER2-positive, metastatic breast cancer that had progressed during treatment with Herceptin. Women were assigned to receive Tykerb alone or Tykerb in combination with Herceptin.
- Women treated with a combination of Tykerb and Herceptin remained free of cancer progression for roughly one month longer than women treated with Tykerb alone (12.0 weeks versus 8.1 weeks).
- Overall survival was roughly three months longer among women treated with Tykerb and Herceptin than among women treated with Tykerb alone (51.6 weeks versus 39 weeks). The difference between groups in overall survival was not statistically significant, however, suggesting that it could have occurred by chance alone.
- Women treated with Tykerb and Herceptin were more likely to experience diarrhea than women treated with Tykerb alone.
For women with advanced HER2-positive breast cancer that has progressed during treatment with Herceptin, these results suggest that the combination of Tykerb and Herceptin more effectively delays cancer progression than Tykerb alone.
The combination of Tykerb and Herceptin is also being evaluated among breast cancer patients with earlier-stage HER2-positive disease.
Reference: Blackwell KL, Burstein HJ, Storniolo AM et al. Randomized study of lapatinib alone or in combination with trastuzumab in women with ErbB2-positive, trastuzumab-refractory metastatic breast cancer. Journal of Clinical Oncology. 2010;28:1124-1130.