Trastuzumab, Cyclophosphamide, and an Allogeneic GM-CSF-secreting Breast Tumor Vaccine for the Treatment of HER-2/Neu-Overexpressing Metastatic Breast Cancer

the vaccine containing a mixture of two GM-CSF-secreting allogeneic breast cancer cell lines (two parts 2T47D-V and one part 3SKBR3-7 mixed in a fixed dose of 5 X 108 cells for each patient and each vaccination cycle) on day 0.

Trastuzumab is a humanized monoclonal antibody specific for the extracellular domain of HER-2/neu that is now one component of the standard of care for both early and late stage HER-2/neu-overexpressing breast cancers. It exerts a pleiotropic antitumor effect by multiple mechanisms. The antibody decreases heterodimer formation with other members of the epidermal growth factor receptor (EGFR) family, thereby indirectly inhibiting signaling through the Ras/Raf/mitogen-activated protein kinases (MAPK) and Phosphatidylinositol 3-kinase(PI3K)/protein kinase B (Akt) pathways. It also inhibits tumor neovascularization, and augments apoptosis both in vitro and in vivo. Trastuzumab prevents cleavage of the extracellular domain of HER-2/neu, thus abrogating the constitutive activation of the remaining membrane-associated intracellular domain.

The doses of Cyclophosphamide are based on previously reported clinical experience as well as our own preclinical data demonstrating augmented vaccine efficacy with CY-modulated vaccination. In particular, 300 mg/m2