The three vaccines were administered sequentially as prime-boost, and each candidate was used only once; this strategy conferred higher titers of HER2-specific immunoglobulins vs. carrier-specific antibodies (which are produced after frequent administration of the same carrier), increasing the toxicity of the antisera toward cancer cells, and prolonging the survival of mice challenged with DDHER2 tumor cells. The gene discussed is ERBB2; the disease is neoplasm.