Metastatic colorectal cancer (CRC) patients will be randomly assigned (3:1) to receive either modified FOLFOX6 [mFOLFOX6] chemotherapy combined with Antigen Pulsed Dendritic Cells (Arm APDC + Chemotherapy), or chemotherapy alone (Arm Chemotherapy). Each patient recruited in the study will receive maximum 12 cycles of (14 days/cycle) mFOLFOX6 chemotherapy. Patients in Arm APDC + Chemotherapy will receive APDC vaccination in addition to chemotherapy in the cycle 1-3 and 7-9, and in cycle 4-6 and 10-12 receive only chemotherapy. APDC + Chemotherapy or Chemotherapy will be stopped in case of disease progression, intolerable toxicities, or patient withdrawal with the consent. After 12 cycles, patients in Arm APDC + Chemotherapy will receive 5-Fluorouracil treatment plus every 3 months APDC therapy and patients in Arm Chemotherapy will receive only 5-Fluorouracil treatment. PFS, ORR and OS will be assessed, and toxicity and immunologic effects will be monitored.