Abstract
Tumor cell-derived heat shock proteins are used as vaccines for immunotherapy of cancer patients. However, current approaches require the generation of custom-made products and are clinically ineffective. To improve the applicability of heat shock protein-based immunotherapy in cancers and to enhance clinical efficacy, we explored combinational treatments in a myeloma setting using pooled heterogeneous or allogeneic myeloma cell line-derived glycoprotein 96 (gp96) as universal vaccines, and clearly demonstrated that pooled but not single gp96 from heterogeneous or allogeneic myeloma cell lines was as effective as autologous gp96 in protecting mice from tumor challenge and rechallenge and in treating established myeloma. We showed that interferon gamma and CD4+ and CD8+ T cells were required for gp96-induced antimyeloma responses and that pooled gp96 induced broader immune responses that protected mice from developing different myeloma. Furthermore, pooled gp96 plus CpG in combination with anti-B7H1 or anti-interleukin-10 monoclonal antibodies were effective in treating mice with large tumor burdens. Thus, this study strongly suggests that pooled gp96 vaccines from myeloma cell lines can replace gp96 vaccines from autologous tumors for immunotherapy and induce immune responses against broader tumor antigens that may protect against tumor recurrence and development of unrelated tumors in vaccinated myeloma patients.