Herceptin: 'Simply Stunning' Results for Treating Breast Cancer

October 22, 2005

Herceptin: 'Simply Stunning' Results for Treating Breast Cancer

In test results researchers describe as "simply stunning", Herceptin (trastuzumab)-a drug already used in treatment of advanced cancer-was shown to halve the recurrence of breast tumors after standard therapy.

However, Herceptin works only in women whose breast tumors contain high amounts HER2, a protein that makes the cancer particularly aggressive; moreover, the drug can cause significant effects, according to a report by Reuters on 20 October.

About 20% of women with breast cancer have this type of tumor, so about 42,000 women in the Untied States could benefit from Herceptin treatment, according to Reuters. About 400,000 people worldwide die from breast cancer each year.

Results of two studies on Herceptin were published in the New England Journal of Medicine (NEJM) on 20 October 2005. Study 1 Study 2

Trastuzumab is sold under brand-name Herceptin by Genentech Inc. in the US and by Swiss drug manufacturer Roche in Europe.

"This is a very important finding. It's likely to change the recommended care for patients. But we need to know more about the side effects and the long-term effectiveness," said Richard Gelber of the Dana-Farber Cancer Institute and an author of one study (the "HERA" study), according to Reuters.

"The results are simply stunning," said Gabriel Hortobagyi of the University of Texas MD Anderson Cancer Center in Houston, according to Reuters. Hortobagyi predicted in a NEJM editorial that the findings "will completely alter our approach to the treatment of breast cancer."

Last May, when preliminary findings were first released at the American Society of Clinical Oncology annual conference, the presenters received a standing ovation, according to Reuters.

Clinical Trials of Herceptin

Researchers conducted three international clinical trials that included over 6,500 patients. Results showed that Herceptin, which has previously primarily been used to enhance survival of patients with advanced HER2 breast cancer, is also highly effective in treating patients in the early stages of breast cancer also, according to a report in TurkishPress.com.

A NEJM summary of the trials described the results as being so impressive that Herceptin could lead to "a cure" for breast cancer.

"This is probably the biggest evidence of a treatment effect I've ever seen in oncology", said Gelber, according to TurkishPress.com. "It is quite remarkable."

Herceptin and HER2

HER2 is a particularly aggressive protein that is involved in up to 30% of the more than one million new breast-cancer cases diagnosed worldwide each year. HER2 is often resistant to chemotherapy.

Herceptin is a monoclonal antibody drug (generic name trastuzumab) that has been used since 1998 to treat women in the advanced stages of HER2-positive breast cancer following chemotherapy. Herceptin blocks HER2 activity to prevent the cancer's recurrence.

In the largest clinical trial to date, in 2001 the Breast International Group teamed up with Roche (Herceptin's European manufacturer) to test the drug's effect on 5,000 women in 39 countries who had been were diagnosed with early-stage HER2-positive breast cancer.

Within one year, women who received Herceptin showed unusually high positive results-the recurrence rate of breast cancer was reduced 46%. Consequently, two years after treatment began, 8% more women were free of breast cancer.

Concerns About Side Effects

As with many new drugs, the good news about Herceptin is tempered by concerns about side effects.

Studies show that trastuzumab may cause heart damage in some women, although these problems usually fade if treatment is discontinued, Gelber reportedly told Reuters. Moreover, women who receive Herceptin after breast-cancer surgery have a higher risk of developing subsequent tumors in the brain or elsewhere in the nervous system.

However, at a time when even marginal improvements in survival rate earn accolades for any drug, a medicine such as Herceptin that nearly halves the rate of tumor recurrence is considered highly significant.

Tamoxifen is the only other cancer drug that produces such good results, according to Hortobagyi. HER2 tumors tend to be resistant to tamoxifen, said Harold Burstein of Dana-Farber, according to Reuters.

Herceptin clinical trials are ongoing, and researchers must still determine whether Herceptin would work more effectively if administered during chemotherapy, or for longer than one year.

For more on Herceptin, visit these websites:

• National Cancer Institute
• BreastCancer.org
• ClinicalTrials.gov (for information on the Herceptin clinical trial)

Sources:
Breast cancer drug Herceptin results 'simply stunning': scientists, TurkishPress.com, 20 October 2005.
Drug halves breast cancer relapse rate for some, Reuters, 20 October 2005.
Trastuzumab after Adjuvant Chemotherapy in HER2-Positive Breast Cancer, Martine J. Piccart-Gebhart, MD, PhD, et al., The New England Journal of Medicine, volume 353, pages 1659-1672, 20 October 2005.
Trastuzumab plus Adjuvant Chemotherapy for Operable HER2-Positive Breast Cancer, Edward H. Romond, MD, et al., The New England Journal of Medicine, volume 353, pages 1673-1684, 20 October 2005.
The Distinctive Nature of HER2-Positive Breast Cancers, Harold J. Burstein, MD, PhD, The New England Journal of Medicine, volume 353, pages 1652-1654, 20 October 2005.

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