Fludarabine given on its own is not recommended as an initial treatment for people with chronic lymphocytic leukaemia (CLL). Fludarabine is not licensed to be prescribed for CLL in combination with other chemotherapy medicines. This is because its 'marketing authorisation', which is normally needed before a drug can be prescribed, did not cover combination treatment. NICE was therefore unable to look at fludarabine in combination with other chemotherapy drugs for people with CLL. The process of giving a drug its marketing authorisation is not related to the NICE appraisal process and it is not carried out by NICE.