Two targeted therapies - lapatinib plus trastuzumab -  are better than one in the fight against HER2-positive metastatic breast cancer, according to study results presented at the CTRC-AACR Annual San Antonio Breast Cancer Symposium, USA.

"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. Kimberly L. Blackwell, associate professor of medicine and director of the Clinical Trials Program in Breast Cancer at Duke University Medical Center.

What makes these results stand out from previous studies, according to Blackwell, is that this study demonstrated an improvement in survival without the incorporation of endocrine therapy or chemotherapy.

"We demonstrated the effectiveness of combined targeted therapy; no other study has examined this combination in a phase III, randomised design," she said.

The researchers randomized 296 metastatic breast cancer patients to receive lapatinib 1,500 mg once a day or lapatinib 1,000 mg once a day in combination with trastuzumab 2 mg/kg every week. Patients’ tumours had progressed on a number of trastuzumab-chemotherapy combination treatments, and patients were faced with limited treatment options.

Lapatinib is an orally active small molecule inhibitor against HER2 and epidermal growth factor receptor for use against solid tumors, and for combination therapy for metastatic breast cancer patients. Trastuzumab is a monoclonal antibody that binds selectively to the HER2 protein, and has demonstrated benefits when combined with chemotherapy in early stage and metastatic breast cancer patients.

Overall survival significantly improved among the patients who used combination therapy, compared with those who were treated with the lapatinib monotherapy, they found. Even after adjusting for prognostic factors, the survival benefit was maintained.

Further, Blackwell and colleagues noted a trend toward a 25 percent reduction in risk of death.
The same combination of lapatinib and trastuzumab from this study is now being compared to either drug alone in the prevention of breast cancer recurrence in patients faced with HER2-positive, early stage breast cancer.

"In the treatment of HER2-positive breast cancer, we have highly effective treatments and when we combine them, we can make a significant difference in survival," she said. "This represents a step forward toward a day when we do not have to give chemotherapy for breast cancer at all."

Source: www.sabcs.org