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New Treatment Paradigms for Breast Cancer: Managing the Flow of New Data

December 12, 2009

Written By Yarissa Reyes

Breaking news continues to emerge from the San Antonio Breast Cancer Symposium . In the third press conference organized by symposium officials, four studies were presented that looked at existing therapies being tested in unique ways as the landscape of acceptable treatment and management of breast cancer continues to shift.

Tykerb Alone Versus Combined with Herceptin for Advanced Breast Cancer

The first study, " Updated Survival Analysis of a Randomized Study of Lapatinib Alone or in Combination with Trastuzumab in Women with HER2-Positive Metastatic Breast Cancer Progressing on Trastuzumab Therapy," was presented in a general session Friday by Kimberly Blackwell, MD, associate professor of medicine and director of the clinical trials program in breast cancer at Duke University Medical Center.

This study concluded that two targeted therapies given together—Lapatinib plus Trastuzumab—are better than one alone in the fight against HER2 positive metastatic breast cancer. Lapatinib (brand name: Tykerb) is a pill, a small molecule that easily enters cancer cells and inhibits HER2 and epidermal growth factor receptor (EGFR) in solid tumors. It is used and for combination therapy for metastatic breast cancer. Trastuzumab (brand name: Herceptin) is a monoclonal antibody that targets and binds only to the HER2 protein and has been shown in previous studies to be tremendously effective when combined with chemotherapy in women with early-stage and metastatic breast cancer.

"These two targeted therapies against HER2, sort of a ‘one-two punch,’ conveyed a more than four month significant improvement in survival when compared to lapatinib alone," said Dr. Blackwell, who is a member of LBBC’s Medical Advisory Board. "This represents a step forward toward a day when we don’t have to give chemotherapy for breast cancer at all."

Avastin and Chemotherapy for Metastatic Disease

The second study, " RIBBON-2: A Randomized, Double-Blind, Placebo-Controlled, Phase III Trial Evaluating the Efficacy and Safety of Bevacizumab in Combination with Chemotherapy for Second-line Treatment of HER2-Negative Metastatic Breast Cancer," was presented in a general session by Adam Brufsky, MD, PhD, associate professor of medicine, associate chief of hematology-oncology and associate director of clinical investigation at the University of Pittsburgh Cancer Institute.

The study results demonstrated that adding Bevacizumab (brand name: Avastin) to chemotherapy as a second-line treatment for metastatic breast cancer significantly improved progression-free survival, the amount of time participants lived without the cancer growing. The findings prompted more questions about the appropriate use of bevacizumab, Dr. Brufsky said.

"Potentially, we have another biologic agent that can improve the survival or at least the progression-free survival of women with metastatic breast cancer," said Dr. Brufsky. "The fact that Bevacizumab has a benefit in first- and second-line treatment really begs the question: ‘Should we be giving this drug to someone through the entire course of metastatic disease?’"

Avastin and Taxotere for Advanced Breast Cancer

The third study, " Final Overall Survival (OS) Results from the Randomized, Double-Blind, Placebo-Controlled, Phase III AVADO Study of Bevacizumab (BV) Plus D for the First-line Treatment of Locally Recurrent (LR) or Metastatic Breast Cancer ," was presented in a general session by David W. Miles, MD, consultant medical oncologist at Mount Vernon Hospital in the United Kingdom.

Results of the AVADO study showed that adding Bevacizumab to Docetaxel Chemotherapy (brand name: Taxotere) significantly improved progression-free survival for women with metastatic breast cancer.

"The AVADO study confirms that the use of bevacizumab in combination with [Docetaxel] increases the chance of reducing tumor burden and prolongs the time for which disease is controlled," said Dr. Miles. "Bevacizumab does not exacerbate the [side effects] of chemotherapy but increases its effect in terms of response rate and progression-free survival. We must make efforts to identify those most likely to benefit based on conventional characteristics or molecular markers, though the latter remain somewhat elusive."

Aromasin Alone Versus a Switch from Tamoxifen for Early, HR Positive Breast Cancer

The final study featured in the press conference, " Five Years of Exemestane as Initial Therapy Compared to 5 Years of Tamoxifen Followed by Exemestane: The TEAM Trial, a Prospective, Randomized, Phase III Trial in Postmenopausal Women with Hormone-Sensitive Early Breast Cancer," was presented Friday in a general session by Daniel Rea, MD, senior lecturer in medical oncology at the University of Birmingham, United Kingdom.

The study, based on data collected over five years from the Tamoxifen Exemestane Adjuvant Multinational trial (TEAM), compared initial therapy with the steroidal aromatase inhibitor Exemestane (brand name: Aromasin) versus a switch from initial therapy of Tamoxifen to Exemestane after a few years. Of the three FDA approved aromatase inhibitors, Exemestane is the only one whose efficacy had not previously been tested against Tamoxifen as initial therapy for hormone-sensitive (estrogen receptor-positive) breast cancer.

"Our hypothesis under examination in this presentation is that Exemestane taken as initial endocrine therapy will improve relapse-free survival compared with starting Tamoxifen," said Dr. Rea. "In addition to analysis by traditional prognosis features, we may be able to identify subgroups defined by relatively simple biomarkers which can be used or combined with standard prognostic variables to rationally select optimal treatment strategies."

Dr. Rea reported results on the nearly 5,000 women who took part in this study. After 5.1 years, he and his research team did not find any significant difference in overall survival between people who took Exemestane alone and those who started with Tamoxifen and switched to exemestane.

Stay tuned for more breaking news from the San Antonio Breast Cancer Symposium and dial in to our SABCS Annual Update teleconference scheduled for January 6 for a recap of the latest information presented at the symposium.