Non-responsiveness to therapeutic tumor vaccination is overcome by functional modulation of myeloid derived suppressor cells

Therapeutic tumor vaccination represents a promising strategy to induce anti-tumor activity in cancer patients. However, usually only a subpopulation of patients benefits from tumor vaccines, whereas others display continuous tumor growth and metastatic spreading. Here we report a similar observation in a B16 melanoma model. Vaccinating these mice with a model tumor antigen and a combination of adjuvants, i.e. TLR-9-ligand CpG and NKT-cell ligand α-galactosylceramide, controlled the tumor in most animals (High-Responders), whereas others showed no clear benefit from the treatment (Non-Responders). No differences…