Protective effects of gp96 vaccines against myeloma development. Results shown are measurements of tumor burdens and survival of mice that received different treatments. Tumor burdens were measured twice every week. Mice were killed when subcutaneous tumors reached 225 mm² or when mice became moribund. (A) Balb/c mice (10 per group) were subcutaneously vaccinated twice with either normal gp96 (g96N); gp96 from tumor A (gp96A), tumor B (gp96B), or tumor C (gp96C); pooled allogeneic gp96 from tumors B and C (gp96BC); or pooled allogeneic gp96 from tumors B, C, and D (gp96BCD) followed by challenge with tumor A. (B) Mice were subcutaneously vaccinated twice with gp96A followed by challenge with tumor A, and surviving mice (5 per group) were rechallenged with tumors A, B, C, or D 8 weeks after the first challenge. (C) Mice were subcutaneously vaccinated twice with gp96BCD followed by challenge with tumor A, and surviving mice (5 per group) were rechallenged with tumors A, B, C, or D 8 weeks after the first challenge. (D) Staining for CD138⁺ myeloma cells (brown) in the tumor nodules of tumor-bearing or injection sites of tumor-free Balb/c mice immunized with autologous gp96A or pooled heterogeneous gp96BCD. Representative results of 1 of 3 independent experiments performed are shown. *P < .05; **P < .01 (compared with controls).