Expression of C-erbB-2/HER-2 in patients with metastatic breast cancer undergoing high-dose chemotherapy and autologous blood stem cell support

C-erbB-2/HER-2 (designated HER-2) is overexpressed in both primary and metastatic breast cancer and predicts poor prognosis. We investigated the expression of HER-2 in patients with metastatic breast cancer undergoing high-dose chemotherapy (HDCT) with autologous blood stem cell (ABSC) support and correlated the presence (positive) or absence (negative) of HER-2 overexpression in these patients with response to treatment, progression-free survival (PFS) and overall survival (OS). The level of HER-2 expression was analyzed in 57 patients with metastatic breast cancer undergoing HDCT with ABSC support. Plasma from peripheral blood was taken at three different time points during the course of treatment and was analyzed using an enzyme immunoassay (EIA) to detect circulating levels of the extracellular portion of HER-2. HER-2 levels were elevated (>0.2 U/mg protein) in 27/57 (47.4%) patients at one or more time points during treatment. The level of HER-2 varied during the course of treatment. Following induction chemotherapy (ICT), five patients who were negative initially, showed overexpression of HER-2. Three patients overexpressed HER-2 only after HDCT/ABSC. Response to treatment was similar in patients independent of plasma HER-2 levels. Overexpression of HER-2 was associated with a significantly shorter PFS (P = 0.004, log rank) and OS (P = 0.003, log rank) after HDCT/ABSC. HER-2 overexpression, patient age, estrogen receptor status, progesterone receptor status, and previous hormone treatment were assessed by univariate and multivariate analysis. Univariate analysis determined that only HER-2 overexpression correlated significantly with decreases in progression free survival (P = 0.005, Cox regression). Decreased overall survival correlated significantly with HER-2 overexpression (P = 0.004) and decreased expression of both estrogen receptor (P = 0.032) and progesterone receptor (P = 0.039). In multivariate analysis of these variables, only HER-2 expression levels proved to be of independent statistical significance in predicting outcome for both PFS (P = 0.007) and OS (P = 0.002). These results suggest that overexpression of HER-2, measured by EIA in plasma may predict a shorter PFS and OS in patients with metastatic breast cancer treated with HDCT and ABSC support.

Cancer cell interactions with injured or activated endothelium

Blood vessels and lymphatics are the most important pathways for dissemination of cancer cells but the entry and exit of these cells into and from the vasculature requires that they pass through barriers formed by the endothelium and its basement membrane. This review summarizes evidence that this step in metastasis can be regulated by microenvironmental influences which alter the properties of this barrier. These phenomena can be attributed to both 'passive' and 'active' responses of the endothelium. The microvasculature is susceptible to perturbation from environmental agents, host cells and cancer cells. There is clinical and experimental evidence that this can upregulate the metastatic process. Using established animal models of pulmonary microvascular injury it has been shown that endothelial damage promotes the localization and metastasis of circulating cancer cells to the lung and that this effect is lost after endothelial repair. Oxidative stress is an effector of vascular damage in several of the experimental models. While endothelial cells appear to be directly susceptible to free radical attack, basement membranes are not. However, oxidative injury of endothelial cells causes release of proteases which can then degrade the basement membrane. This event is associated with generation of tumor cell chemoattractants and enhances cancer cell invasion of vascular basement membranes in vitro. Vascular endothelial cells are also susceptible to stimulation by systemic mediators including cytokines, thrombin, or endotoxin which induce a series of active responses in the vessel wall. These perturbed endothelial cells synthesize and express cell surface adhesion molecules which can interact with cancer cells. They also release chemoattractants which stimulate cancer cell motility. We postulate that such responses endow the vessel wall with the potential to act as a determinant of metastatic rate.