Lapatinib used in tandem with paclitaxel demonstrates significant clinical activity in HER2-overexpressing (HER2+) patients with metastatic breast cancer, according to results released today at the 14th European Cancer Conference (ECCO).
Lapatinib is an oral tyrosine kinase inhibitor of EGFR/HER2 that was recently approved in the U.S., Switzerland, and several other countries worldwide for use in combination with capecitabine for HER2+ advanced/metastastic breast cancer pretreated with taxanes, anthracyclines, and trastuzumab-based therapy.
The taxane paclitaxel has shown activity alone and in combination in HER2+ breast cancer.
Dr. Richard Finn, MD, assistant professor of hematology/oncology at the Geffen School of Medicine at UCLA in Los Angeles, California, and colleagues elsewhere analyzed biomarkers in 580 women whose HER2 status was unknown at the time they enrolled in a phase III trial comparing lapatinib with pacelitaxel versus paclitaxel plus placebo as first-line treatment for metastatic breast cancer.
Initial results from the trial, known as EGF30001, documented a direct correlation between lapatinib efficacy and HER2+ overexpression.
Importantly, the new analysis revealed that biomarkers correlated with clinical efficacy in 579 patients.
Specifically, the data showed that in a subset of 91 patients determined to be HER2+, lapatinib plus paclitaxel demonstrated significant superiority over the paclitaxel plus placebo group in key measures of clinical activity. The median progression-free survival was 34.4 weeks in the lapatinib/paclitaxel group versus 22.6 weeks in the paclitaxel plus placebo group (p=0.007), and the median time to disease progression was 35.1 versus 25.1 weeks for the two groups, respectively, p=0.0107. A complete or partial response was documented in 60% versus 36% of the two groups, respectively, p=0.027.
The lapatinib/paclitaxel combination did not confer additional benefit in patients with HER2- disease.
“The study bolsters evidence in support of lapatinib’s potential to improve the clinical management of HER2+ metastatic breast cancer,” Professor John Crown, consultant medical oncologist at St. Vincent’s University Hospital in Dublin, Ireland, said.
There are approximately 430,000 new cases of breast cancer per year in Europe. In 2006, breast cancer accounted for one in seven (13.5%) of all newly diagnosed cancers, with 132,000 deaths due to the disease. Roughly a third of breast tumors are HER2+, which is a recognized marker for poor prognosis. Up to 40% of HER2+ patients are unresponsive to trastuzumab therapy.
By Jill Stein
Jill Stein is a Paris based medical writer
Jillstein03 at cs.com