2. Signed and dated written informed consent for tumour biopsies. If the tumour is found not to be safely accessible the biopsy will not be taken. Accessible lesions are defined as those which are biopsiable and amenable to repeat biopsy, unless clinically contraindicated. In this case the patient will remain in the study and there will be no penalty or loss of benefit to the patient and they will not be excluded from other aspects of the study.