The Mutanome Engineered RNA Immuno-Therapy (MERIT) study introduces a novel concept for Individualized Cancer Immunotherapy (IVAC®) to treat each patient with the relevant and immunogenic RNA vaccines for a given patient's tumour. The TNBC-MERIT trial uses two complementary strategies, the IVAC® WAREHOUSE and the IVAC® MUTANOME concept, resulting in two custom-made IVAC® investigational medicinal products (IMPs) (IVAC_W_bre1_uID and IVAC_M_uID) for each individual patient.