Multiple antigens in a breast cancer vaccine result in a higher immune response rate in breast cancer patients

Abstract

2607 Background: We have previously reported that whole cell preparations of breast carcinoma cells from either an autologous or allogeneic source (MCF-7 cells) and tumor antigens (CA 15–3, CEA and CA125) could produce immune responses, increased lymphocyte proliferation in a Lymphocyte Blastogenesis Assay (LBA), in breast cancer patients vaccinated with tumor cells, tumor antigens and two biological adjuvants (IL-2 and GM-CSF). The present study was undertaken to determine if the use of multiple antigens, cells and tumor antigens, in a breast cancer vaccine could increase the proportion of patients demonstrating an immune response to vaccination. Methods: Twenty-four patients were vaccinated 6 times with allogeneic cells, CA 15–3, CEA, and CA 125 antigens. LBAs were done before and after vaccination and the ratio of antigen to the media control was determined for each antigen before and after vaccination (a ratio of 1 means no stimulation by the antigen). The post-vaccine ratios for each patient's antigens were compared to the pre-vaccine ratio and an increase of 2 times was considered a significant immune response. Results: The following immune response rates were found: 25% (6 of 24 patients) for allogeneic MCF-7 cells, 21% (5 of 24 patients) for CA 15–3, 25% (6 of 24 patients) for CEA and 22% (5 of 23 patients) for CA 125. When an immune response to either the whole cell or any one of the tumor antigens was considered an immune response for that patient, then 58% (14 of 24) of the patients had immune responses. Conclusions: Whole cell preparations of allogeneic MCF-7 cells and tumor antigens (CA 15–3, CEA and CA 125) can induce immune responses in breast cancer patients. Each antigen produces an immune response, as measured by a LBA, in approximately 25% of the patients but by using multiple antigens over half of the patients will have an immune response to one or more of the antigens. This suggests that the use of multiple antigens in cancer vaccines may increase the clinical response rate, but a larger study with long-term follow-up will be needed. No significant financial relationships to disclose.