Activity of TroVax® Alone vs. TroVax® Plus GM-CSF in Patients With Prostate Cancer

Inclusion Criteria: * Histologically confirmed adenocarcinoma of the prostate. * Stable or progressive disease after androgen deprivation. * Karnofsky Performance Status ≥ 60%. * At least one prior taxane based chemotherapy for prostate cancer therapy (or patient refusal of chemotherapy) * At least four weeks have lapsed since prior chemotherapy (if administered) * Patients on stable doses of bisphosphonates that show subsequent tumor progression may continue on this medication; however, patients are not allowed to initiate bisphosphonate therapy within one month prior to starting therapy or throughout the study. * Major surgery or radiation therapy completed ≥ 4 weeks prior to enrollment. * Clinically immunocompetent. All patients are assumed to be immunocompetent unless they have been diagnosed as being immunosuppressed, are receiving oral steroids, immunosuppressive chemotherapy for oncology disorders or are receiving immunosuppressive therapy following transplant. * Free of clinically apparent autoimmune disease (no prior confirmed diagnosis or treatment for autoimmune disease including Systemic Lupus Erythematosis, Grave's disease, Hashimoto's thyroiditis, multiple sclerosis, insulin dependant diabetes mellitus or systemic (non-joint) manifestations of rheumatoid disease). * Absolute Lymphocyte Count ≥ 500/µl, ANC \>1200/µl, Platelet count \>100,000/µl, Hemoglobin \> 8 mg/dl * No evidence of active ischemia on ECG Exclusion Criteria: * Patients receiving any other hormonal therapy, including any dose of megestrolacetate (Megace), Proscar (finasteride), any herbal product known to decrease PSA levels (e.g., Saw Palmetto and PC-SPES), or any systemic corticosteroid must discontinue the agent for at least 4 weeks prior to enrollment. Progressive disease (as defined above) must be documented after discontinuation of the hormonal therapy. * Patients that initiate bisphosphonate therapy within one month prior to starting therapy or throughout the study. * No supplements or complementary medicines/botanicals are permitted during the study * Major surgery or radiation therapy completed ≤ 4 weeks prior to enrollment. * Prior radiopharmaceuticals (strontium, samarium) within 8 weeks prior to enrollment. * "Currently active" second malignancy, other than non-melanoma skin cancer. Patients are not considered to have a "currently active" malignancy if they have completed therapy and are considered by their physician to be at least less than 30% risk of relapse. * Serious intercurrent infections or nonmalignant medical illnesses that are uncontrolled. * Psychiatric illnesses/social situations that would limit compliance with protocol requirements. * Liver function tests (ALT, AST) more than 1.5 x upper limit of normal (ULN). The bilirubin must be within normal limits. * Renal function creatinine ≥1.5 x ULN. * Known allergy to egg proteins. * Known allergy to neomycin. * History of allergic response to previous vaccinia vaccinations. * Chronic oral corticosteroid use (especially anti-emetics) unless prescribed as replacement therapy in the case of adrenal insufficiency. * Known to test positive for HIV or hepatitis B or C. * Clinical indication of reduced cardiac function or an ejection fraction of ≤ 40%. * Requirement for radiotherapy (this is a sign of disease progression and is classed as a withdrawal criterion). * Concurrent chemotherapy, immunotherapy and radiation therapy * No investigational or commercial agents or therapies other than those included in protocol treatment may be administered with the intent to treat the patient's malignancy.