Vaccination of Women with Metastatic Breast Cancer, Using a Costimulatory Gene (CD80)-Modified, HLA-A2-Matched, Allogeneic, Breast Cancer Cell Line: Clinical and Immunological Results

MDA-MB-231, an HLA-A2+, HER2/neu+ allogeneic breast cancer cell line genetically modified to express the costimulatory molecule CD80 (B7-1), was used to vaccinate 30 women with previously treated stage IV breast cancer. Expression of CD80 conferred the ability to deliver a costimulatory signal and thereby improved the antigen presentation capability of the tumor cells to patient T cells in vitro. Patients were vaccinated with 107 or 108 irradiated gene-modified tumor cells with granulocyte-macrophage colony-stimulating factor (GM-CSF) or BCG, three times at 2-week intervals and then monthly until progressive disease developed. GM-CSF-related flulike symptoms and minor injection site reactions were observed frequently. Prolonged disease stabilization was observed in four patients but no objective tumor regressions were seen. Immune responses were measured in matched peripheral blood samples collected before and after treatment from 9 of 15 patients treated at the 108 tumor cell dose. Four patients exhibite...