Virulizin is an immunotherapy drug preparation that is thought to stimulate the patient's immune system, which in turn may slow the growth of tumors. It is presented in vials as a sterile preparation for IM injection. The purpose of the trial is to investigate if Virulizin in combination with gemcitabine provides better efficacy than gemcitabine alone (with placebo) against pancreatic cancer.Virulizin® efficacy will continue to be assessed if chemotherapy is changed to 5-Fluorouracil.