IBCSG Trial 22-00 Serum Substudy

Overview

The serum protein research study is a substudy of the core study 'Maintenance Chemotherapy in Hormone Non-responsive Breast Cancer'. This substudy is an evaluation of blood proteins and their relationship to breast cancer treatment. It will assess the levels of Vascular Endothelial Growth Factor (VEGF), Soluble HER2 Protein (NRP, neu-related protein) and Vascular Cellular Adhesion Molecule-1 (VCAM-1) in serum samples of patients' blood at different time points. The goal is to evaluate differences in serum levels between patients receiving the maintenance chemotherapy and those who do not. The serum levels will be also examined to determine if they vary during the three year period of evaluation. In addition, the serum levels of patients who have a recurrence of their breast cancer will be compared with those who remain disease free. The information obtained from these studies will enable breast cancer physicians to better tailor therapies for future patients.

The Serum Substudy will assess the levels of Vascular Endothelial Growth Factor (VEGF), Soluble HER2 Protein (NRP, neu-related protein) and Vascular Cellular Adhesion Molecule-1 (VCAM-1) in patients' serum samples at different time points. VEGF: Angiogenesis plays a central role in tumor progression of solid neoplasia. The switch from the avascular to the vascular phase is generally accompanied by rapid primary tumor growth and local invasiveness. Furthermore, angiogenesis is also necessary both at the beginning and end of the development of distant metastasis and is implicated in the phenomenon of dormant micrometastases. Antiangiogenic peptides may be altered in the serum or urine of cancer patients. In a study of 144 breast cancer patients, angiogenic protein basic fibroblast growth factor was abnormally elevated in the urine in 29% of cases and in the serum in 10%. Another angiogenic protein, vascular endothelial factor (VEGF), was abnormally elevated in the serum in over 70% of these breast cancer patients (4). Since platelets bind VEGF, platelet values will also be assayed. HER2-ECD: No data are available regarding the presence of serum HER2-ECD (NRP) levels in c-erbB2 negative tumors, but the extracellular domain of the c-erbB2 oncogene product (NRP) is detectable in sera of 30-60% of patients with cerbB2 positive tumors. Many reports have correlated the elevated serum levels of the cerbB2 with gene amplification and c-erbB2 overexpression in tumor. These data support the hypothesis that the level of NRP protein can reflect the presence of c-erbB2 positive cells and that modification of the factor can predict a decrease of c-erbB2 positive cells during standard adjuvant chemotherapy. Moreover, change in the detectable NRP during the maintenance phase can suggest a possible modification in the biology and/or behaviour of hypothetic micrometastasis. VCAM-1: In tumors, endothelial VCAM-1 play a major role in the adhesion of leukocytes to the endothelium, suggesting a relationship between cellular adhesion and angiogenesis. Soluble VCAM-1 has been implicated in the mediation of angiogenesis and some studies support the hypothesis that VCAM-1 provides surrogate markers for endothelial activation and angiogenesis occurring during cancers. Recently, VCAM-1 serum levels have been associated with microvessel density and response to endocrine therapy.