Based on the results of a Phase III clinical trial, the U.S. Food and Drug Administration has approved two new Herceptin® (trastuzumab)-containing regimens for the adjuvant treatment of early HER2-positive breast cancer. One of these regimens does not contain an anthracycline, and appears to be less likely than anthracycline-containing regimens to cause heart problems.
Herceptin is a monoclonal antibody that targets the HER-2 protein-a protein that is involved in cellular growth and replication and overexpressed in roughly 30% of breast cancers. The binding of Herceptin to HER-2 prevents or reduces replication of cancer cells.
The combination of Herceptin with an anthracycline-based chemotherapy regimen improves breast cancer outcomes compared with chemotherapy alone but can result in severe heart complications. Researchers therefore continue to evaluate ways to maintain the effectiveness of Herceptin and chemotherapy while minimizing the risk of heart problems.
A Phase III clinical trial known as BCIRG 006, which enrolled patients from around the world, evaluated the possibility that non-anthracycline-containing chemotherapy regimens used in combination with Herceptin may reduce the risk of heart complications while maintaining efficacy of treatment.
This trial included 3,222 women with HER2-positive breast cancer. All women had cancer that had spread to lymph nodes or that was high-risk in spite of no lymph node involvement. Patients were randomly assigned to receive one of the following treatments:
- AC-T: doxorubicin and cyclophosphamide followed by Taxotere® (docetaxel)
- AC-TH: doxorubicin and cyclophosphamide followed by Taxotere with Herceptin
- TCH: Taxotere and carboplatin with Herceptin (TCH)
Patients in the two Herceptin groups (AC-TH and TCH) were compared with patients who did not receive Herceptin (AC-T). Researchers also assessed differences in effectiveness and toxicity between the two Herceptin groups: AC-TH contains an anthracycline (doxorubicin) and TCH does not.
- Compared with patients treated with AC-T, patients treated with either AC-TH or TCH had better overall survival. Risk of death was 34% lower among patients treated with TCH and 42% lower among patients treated with AC-TH.
- Risk of congestive heart failure was lower among patients treated with TCH (0.4%) than among patients treated with AC-TH (1.9%).
Based on these results, both the TCH and the AC-TH regimens were approved. TCH does not include an anthracycline, and appears to have a low rate of heart complications. Patients with early HER2-positive breast cancer may wish to talk with their doctor about the range of adjuvant therapy options available.
Reference: Cancer International Research Group (CIRG) Press Release. First taxane-based non-anthracycline containing chemotherapy in combination with Herceptin (TCH) for HER2 positive early breast cancer patients obtains approval from the FDA. May 29, 2008. Available at: http://www.bcirg.org/Internet/Press+Releases/default.htm Accessed May 30, 2008.