Abstract 4756: Anti-melanoma-specific humoral immune responses in vitro in patients vaccinated with DC-rIL-2-VMO

Abstract

Abstract Introduction: DC-rIL-2-VMO, an allogeneic cellular melanoma vaccine consisting of five melanoma cell lines, a recombinant vaccinia virus encoding for IL-2, as well as dendritic cells, has previously been shown to generate a potent cellular response in murine tumor models. We now demonstrate that this vaccine also has the capacity to generate a sustained humoral response in vitro. Methods: To detect anti-tumor antibodies in pre- and post-vaccinated melanoma patients’ sera, a mixed hemadsorption assay (MHA) was used. The binding of human antibody from diluted patients’ sera (1:05, 1:15 and 1:45) to cultured melanoma cells (Mel-2, Mel V, GLM-2 and KFM cells) was determined as indicator cells, sheep red blood cells (SRBC) coated sequentially with mouse anti-SRBC sera, goat sera against mouse sera, and mouse anti-human IgG sera to detect binding of human anti-melanoma antibodies. Results: Out of four patients evaluated with Stage IIIA-C and Stage IV resected with no evaluable disease (NED), three patients’ post-vaccination sera showed antibodies specifically binding to melanoma cell lines. Antibodies from two of the patients’ sera showed moderate to strong binding to three different melanoma cell lines (Mel 2, Mel V and GLM-2). Additionally, antibodies from patients’ sera and sera from two normal healthy donors did not show any binding to colorectal carcinoma (SW1116) cells (CRC), a negative control. Conclusions: Treatment of patients with Stage IIIA-C and Stage IV melanoma resected to be NED with DC-rIL-2-VMO induced a tumor-specific antibody response. The presence of these anti-melanoma antibodies suggests that this vaccine may be effective in slowing the progression of melanoma in some patients via cellular and humoral immune mechanisms. DC-rIL-2-VMO has been FDA-approved for Phase I trials. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4756.