Background
The antibodies that block immunological checkpoints have been successfully applied for the treatment of cancer. Similar effects are expected by molecular targeted therapy, which primarily aims to inhibit molecular pathways for tumor cell growth and survival. Such small molecular drugs may modulate the immune system, which raises the possibility that targeted therapy might be effectively combined with immunotherapy. Sunitinib, a tyrosine kinase inhibitor currently in use for the treatment of metastatic renal cell carcinoma (mRCC), has been reported to modulate immunosuppressive cells such as myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Tregs). We conducted a clinical study of dendritic cell (DC)-based immunotherapy together with Sunitinib in mRCC patients in an effort to enhance immunotherapeutic efficacy by inhibiting immunosuppressive cells.