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Medline ® Abstract for Reference 21

of 'HER2 and predicting response to therapy in breast cancer'

Serum HER-2/neu and relative resistance to trastuzumab-based therapy in patients with metastatic breast cancer.
Ali SM, Carney WP, Esteva FJ, Fornier M, Harris L, Köstler WJ, Lotz JP, Luftner D, Pichon MF, Lipton A, Serum HER-2/neu Study Group
Cancer. 2008;113(6):1294.
BACKGROUND: Previous reports based on small patient numbers suggested that changes in serum HER-2/neu levels may predict response or lack of response to trastuzumab-based therapies in metastatic breast cancer (MBC). The objectives of this study were to pool data from 307 patients with MBC from 7 medical institutions to validate that the serum HER-2/neu profile predicts patient resistance to trastuzumab and to establish a clinically relevant cutoff.
METHODS: This was an international, multicenter, retrospective analysis of individual pooled data from 307 patients with MBC who were treated with first-line trastuzumab-based therapy. Serum was collected at baseline and 30 to 120 days after the initiation of trastuzumab therapy. A serum HER-2/neu decrease>or=20% (receiver operating curve analysis) was defined as a significant HER-2/neu change.
RESULTS: Of the 307 patients with MBC, 191 patients (62%) had a significant decline (>20%) in serum HER-2/neu and 116 patients (38%) didnot. The objective response rate was 57% for patients who achieved this decline in serum HER-2/neu (>20%) compared with 28% for patients who did not. Patients who achieved this decline in serum HER-2/neu also had a significantly longer time to disease progression (320 days vs 180 days; P<.0001), longer duration of response (369 days vs 230 days; P = .008), and longer overall survival (898 days vs 593 days; P<.018).
CONCLUSIONS: In this pooled analysis of 307 patients with MBC, individuals who did not achieve a significant decline (>or=20%) in serum HER-2/neu levels had decreased benefit from trastuzumab-based therapy, and these patients should be considered for clinical trials evaluating additional HER-2/neu-targeted interventions.
Department of Hematology-Oncology, Penn State Hershey Cancer Center, Penn State University/Hershey Medical Center, Hershey, Pennsylvania 17033, USA.