The dHER2 + AS15 candidate Antigen-Specific Cancer Immunotherapeutic (ASCI) contains a recombinant protein termed dHER2, which is a truncated version of the HER2 protein. HER2 is a protein that is commonly overexpressed in breast cancer. This protein is combined with the immunological adjuvant AS15 Adjuvant System from GSK (GlaxoSmithKline), which is a liposomal formulation containing three immunostimulatory components.