Modified Vaccinia Ankara (MVA) Vaccine Study

Inclusion Criteria: * Histologically confirmed NPC, in which the presence of EBV within the malignant cells has been demonstrated by (1) EBER (EBV early RNA) in situ hybridisation in more than 50% of the malignant cells, or (2) undifferentiated or poorly differentiated carcinoma histology in association with a raised serum titer of IgA to EBV VCA. * Patients in remission from disease, ie complete response (CR) or unconfirmed complete response (CRu). * Completion of standard therapy for malignancy at least 12 weeks before trial entry. * Written informed consent and the ability of the patient to co-operate with treatment and follow up must be ensured and documented. * Age greater than 18 years. * World Health Organisation (WHO) performance status of 0 or 1 * Life expectancy of at least 4 months. * Haematological and biochemical indices (these measurements must be performed within 28 days prior to the patient going on study): * Haemoglobin (Hb) \> 10.0 g/dl * Lymphocytes \> 1.0 x 109/L (or above the lower limit of normal range of institutional laboratory) * Neutrophils ≥ 1.5 x 109/L * Platelets (Plts) ≥ 100 x 109/L * baseline liver function tests : * Serum bilirubin ≤ 1.5 x upper normal limit * Serum alkaline phosphatase, alanine amino-transferase (ALT) and/or aspartate amino-transferase (AST) \< 1.5 x ULN. * baseline renal function test: * calculated creatinine clearance \> 50ml/min Female patients of child-bearing potential are eligible, provided they have a negative pregnancy test prior to enrolment and agree to use appropriate medically approved contraception during the study up to six months after the last vaccination. * Male patients must agree to use appropriate medically approved contraception during the study up to six months after the last vaccination. Exclusion Criteria: * Receiving current chemotherapy or radiotherapy, or received within 12 weeks of trial entry. * Known chronic active infection with Hepatitis B, Hepatitis C or Human Immunodeficiency Virus (HIV). * Current active autoimmune disease. * Current active skin diseases requiring therapy (psoriasis, eczema etc). * Ongoing active infection. * History of anaphylaxis or severe allergy to vaccination. * Allergy to eggs or egg products. * Previous myeloablative therapy followed by an autologous or allogeneic haematopoietic stem cell transplant. * Patients who have had a splenectomy or splenic irradiation, or with known splenic dysfunction. * Receiving current immunosuppressive medication, including corticosteroids. * Pregnant and lactating women. * Ongoing toxic manifestations of previous treatment. Exceptions to this are alopecia or certain Grade 1 toxicities which in the opinion of the Investigator and Cancer Research UK should not exclude the patient. * Major thoracic and/or abdominal surgery in the preceding four weeks from which the patient has not yet recovered. * Patients with any other condition which in the Investigator's opinion would not make the patient a good candidate for the clinical trial. * Concurrent congestive heart failure or prior history of class III/ IV cardiac disease