Pilot Study to Establish Safety & Efficacy of a Combination of Dexamethasone and Lenalidomide in Patients With Relapsed or Refractory Chronic Lymphocytic Leukaemia (CLL)

Inclusion Criteria:

* Diagnosis of relapsed or refractory CLL as defined by the NCIWG criteria, requiring treatment
* 1-3 lines of prior therapy
* Fludarabine- or Alemtuzumab-based therapy inappropriate
* WHO Performance status ≤2
* Age ≥ 18 years
* Life expectancy \> 6 months
* Male and female subjects must meet the inclusion criteria for the Lenalidomide Pregnancy Prevention Risk Management Plan.
* Male and female subjects must agree to follow the Lenalidomide Pregnancy Prevention Risk Management Plan (including contraception 4 weeks before, during and 4 weeks after treatment for females of child-bearing potential).
* Signed informed consent

Exclusion Criteria:

* Previously untreated CLL
* Fit patients for whom alemtuzumab or fludarabine- based therapy would be appropriate
* Creatinine clearance \< 30ml/min calculated by Cockcroft-Gault
* Bilirubin \> 1.5 x upper limit of normal
* Patients with marrow suppression resulting in significant cytopenia (Neutrophils \<0.5 x 109/l, Platelets \<30 x 109/l).
* Radiotherapy, radioimmunotherapy, biological therapy, chemotherapy or other investigational therapy within 4 weeks prior to study Day 1.
* Known infection with HIV, hepatitis B or hepatitis C.
* Uncontrolled glaucoma, diabetes mellitus, hypertension or symptomatic peptic ulcer disease
* Peripheral neuropathy \> grade 1
* Proven or suspected transformation to aggressive B-cell malignancy (e.g. large -B-cell lymphoma, Richter's syndrome, or PLL).
* Second malignancy requiring treatment other than non metastatic skin or prostate tumours
* Any medical condition that would require long-term use (\>1 month) of systemic corticosteroids at a dose greater than 5mg/day of prednisolone during study treatment.
* Active uncontrolled bacterial, viral or fungal infections Cardiac failure, myocardial infarction within 6 months prior to study day 1, or evidence of ischaemia on ECG within 30 days prior to study day 1.
* Epileptic disorders requiring anticonvulsant therapy
* Major surgery, other than diagnostic surgery within 4 weeks prior to Study Day 1.
* Pregnant or currently breastfeeding.
* Patients who for other reasons are not expected to complete the study
* Subjects with a known allergy to allopurinol