Dyar, Stephen

BACKGROUNDIncreased soluble human epidermal growth factor receptor 2 (sHER2) is an indicator of a poor prognosis in HER2‐positive metastatic breast cancer. In this study, the authors evaluated levels of sHER2 during treatment and at the time of disease recurrence in the adjuvant North Central Cancer Treatment Group N9831 clinical trial.METHODSThe objectives were to describe sHER2 levels during treatment and at the time of recurrence in patients who were randomized to treatment arms A (standard chemotherapy), B (standard chemotherapy with sequential trastuzumab), and C (standard chemotherapy with concurrent trastuzumab). Baseline samples were available from 2318 patients, serial samples were available from 105 patients, and recurrence samples were available from 124 patients. The cutoff sHER2 value for the assay was 15 ng/mL. Statistical methods included repeated measures linear models, Wilcoxon rank‐sum tests, and Cox regression models.RESULTSThere were differences between groups in terms of age, menopausal status, and hormone receptor status. Within treatment arms A, B, and C, patients who had baseline sHER2 levels ≥15 ng/mL had worse disease‐free survival than patients who had baseline sHER2 levels <15 ng/mL (arm A: hazard ratio, 1.81; P = .0014; arm B: hazard ratio, 2.08; P = .0015; arm C: hazard ratio, 1.96; P = .01). Among the 124 patients who experienced disease recurrence, sHER2 levels increased from baseline to the time of recurrence in arms A and B but remained unchanged in arm C. Patients who had recurrence sHER2 levels ≥15 ng/mL had a shorter survival after recurrence with a 3‐year overall survival rate of 51% compared with 77% for those who had recurrence sHER2 levels <15 ng/mL (hazard ratio, 2.36; 95% confidence interval, 1.19‐4.70; P = .01).CONCLUSIONSIn patients with early stage, HER2‐positive breast cancer, a high baseline sHER2 level was identified as a prognostic marker associated with shorter disease‐free survival, and a high sHER2 level at recurrence was predictive of shorter survival. Cancer 2013;119:2675–2682. © 2013 American Cancer Society.

There is an ongoing need for development of new chemotherapeutic regimens for metastatic breast cancer [mBC], especially when tumors lack therapeutic targets such as the estrogen or progesterone receptor [ER/PR], or the human epidermal growth factor receptor-2 [HER2]. Capecitabine is an orally bioavailable fluoropyrimidine approved for monotherapy in mBC, and bevacizumab is a monoclonal antibody targeting vascular endothelial growth factor which has shown to be active in mBC and tolerable in combination with other chemotherapeutics. The combination of these two agents has been explored in multiple phase II and III clinical studies, with improvements in progression-free survival and overall response rates noted as compared to capecitabine monotherapy. However, the use of bevacizumab in combination with capecitabine and other chemotherapy agents for mBC remains beset with controversy due to safety concerns, cost issues, and pending regulatory decisions.