Inclusion Criteria:

1. Patients who are willing and able to provide written informed consent to participate in the study.
2. Patients with histologically confirmed metastatic or recurrent squamous cell carcinoma of the head or neck currently documented as "progressive disease"
3. Head and neck cancer patients with more than one tumour mass where at least one tumour mass is accessible for intratumoural injection and both tumour masses can be measured at periodic intervals for tumour size using callipers, ultrasound, CT scans or other radiological methods
4. All patients to have histologically confirmed squamous cell carcinoma of the head and neck (excluding nasopharyngeal) that had recurred or relapsed after surgery and/or radiotherapy and/or chemotherapy for primary tumours.
5. Patients considered unsuitable for surgery and radiotherapy with the volume of the target injectable tumour being no greater than 7 cm3 or less than 0.5 cm3..
6. The tumour mass to be intratumourally injected to be easily accessible for injection and amenable to measurement by physical examination or radiographically
7. Patients to be 18 years or older
8. Tumours must bear ICAM-1 receptors with or without DAF-expressing receptors.
9. Absence of circulating antibodies to CVA21 (titre < 1:16).

10. Adequate haematological, hepatic and renal function, defined as:

    • ANC > 1.5 x 109/L, platelets > 100 x 109/L
    • Bilirubin < 20µmol/L, AST < 2.5 times the upper limit of normal
    • Calculated creatinine clearance > 30 mL/minute

    Adequate immunologic function, defined as:

    • Serum IgG > 5g/L
    • T cell subsets within normal limits
11. Fertile males and females must agree to the use of an adequate form of contraception. Hormonal contraceptives should be supplemented with an additional barrier method. Negative pregnancy test is required in female patients of child-bearing potential.

Exclusion Criteria:

1. Patients receiving radiotherapy to the proposed injected tumour or radiotherapy within the last 3 weeks
2. Performance status > 1 on the ECOG scale
3. Life expectancy < 6 months.
4. Pregnancy or breastfeeding.
5. Primary or secondary immunodeficiency, including immunosuppressive disease, and immunosuppressive doses of corticosteroids (e.g. prednisolone > 7.5mg per day) or other immunosuppressive medications including cyclosporine, azathioprine, interferons, within the past 4 weeks.
6. Positive serology for HIV, Hepatitis B or Hepatitis C.
7. Splenectomy.
8. Presence of uncontrolled infection.
9. Any uncontrolled medical condition that in the opinion of the Investigator is likely to place the patient at unacceptable risk during the study or reduce their ability to complete the study
10. Participation in another study requiring administration of an investigational drug or biological agent within the last 4 weeks
11. Known allergy to treatment medication or its excipients