• 18 years of age or over.

• Life expectancy ≥ 6 months.

• Pathologically confirmed MCL, with documentation of monoclonal B cells that have a chromosome translocation t(11;14)(q13;q32) and/or overexpress cyclin D1, D2 or D3.

• Stage II-IV MCL measurable by CT imaging or by white cell count (WCC)/BM infiltration.

• 'Indolent' MCL, defined as 1 or more of the following:

‣ Observation with no treatment for a minimum of 6 months after the initial diagnosis

⁃ Leukaemic non-nodal variant (lymphocytosis/splenomegaly only without nodal involvement)

⁃ Low tumour volume (largest lymph node ≤ 3cm in maximal diameter), proliferation fraction (Ki67 or equivalent) ≤30% and classical morphology (non-blastoid/pleomorphic)

• Eastern Cooperative Oncology Group (ECOG) Performance Status 0-2.

• Absolute neutrophil count ≥1.0 x 109/L and platelets ≥75 x 109/L independent of growth factor support.

• AST and/or ALT ≤3 x upper limit of normal (ULN).

• Total Bilirubin ≤1.5 x ULN unless due to Gilberts syndrome or of non-hepatic origin unless directly attributable to the patient's MCL.

⁃ Calculated creatinine clearance ≥30 mL/min. Glomerular filtration rate (GFR) ≥30 mL/min directly measured with 24 hour urine collection, or creatinine clearance calculated according to the modified formula of Cockcroft and Gault (for men: GFR ≈ ((140 - age) x bodyweight)/ (72 x creatinine), for women x 0, 85).

⁃ Able to give voluntary written informed consent.

⁃ Willing and able to participate in all required evaluations and procedures in this study protocol including swallowing capsules without difficulty.

⁃ Negative serum or urine pregnancy test for women of childbearing potential (WOCBP).

⁃ Willing to comply with the contraceptive requirements of the trial.