• Patient must be ≥ 18 years of age.

• Patient must have a confirmed diagnosis of MCL according to World Health Organisation (\[WHO\] 2008) criteria, and have received at least one prior line of systemic therapy for their disease. Patients recently commenced on ibrutinib (≤4 weeks) will be allowed to enrol as long as at the time of enrolment there is measurable disease and no disease progression.

• Patient requires treatment in the opinion of the investigator, and has at least one site of assessable disease not previously irradiated (such as lymph node with largest diameter ≥1.5cm, or unequivocal hepatomegaly/splenomegaly).

• Patient has an Eastern Cooperative Oncology Group (ECOG) performance score of ≤ 2 .

• Patient must have adequate bone marrow function independent of growth factor support at screening as follows:

‣ Absolute Neutrophil Count (ANC) ≥ 0.75 x 109/L (neutropenia due to marrow infiltration may be supported by growth factors)

⁃ Platelets ≥ 50 x 109/L (≥ 30 x 109/L if reduced counts due to marrow infiltration; entry platelet count must be independent of transfusion within 7 days)

• Patients must have adequate coagulation, renal, and hepatic function, per laboratory reference range at screening as follows:

‣ Activated partial thromboplastin time (aPTT) and prothrombin time (PT) ≤1.5 × the upper limit of normal (ULN)

⁃ Calculated creatinine clearance of at least 30 mL/min using the Cockcroft-Gault equation or a 24-hour urine collection (Appendix 2)

⁃ Aspartate aminotransferase (AST) or Alanine aminotransferase (ALT) ≤ 3.0 × ULN of institution's normal range

⁃ Bilirubin ≤1.5 × ULN. Patients with documented Gilbert's Syndrome may have a bilirubin \> 1.5 × ULN

• Female patients of childbearing potential and non-sterile male patients (with partner(s) of child bearing potential) must practice at least one of the following methods of birth control with partner(s) from initial study drug administration to 90 days after the last dose of study drug:

‣ Total abstinence from sexual intercourse as the preferred life style of the patient; periodic abstinence is not acceptable

⁃ Surgically sterile partner(s); acceptable sterility surgeries are: vasectomy, bilateral tubal ligation, bilateral oophorectomy or hysterectomy

⁃ Intrauterine device

⁃ Double-barrier method (contraceptive sponge, diaphragm or cervical cap with spermicidal jellies or cream AND a condom)

⁃ Hormonal contraceptives (oral, parenteral or transdermal) for at least 3 months prior to study drug administration

• Female patients of childbearing potential must have a negative serum (beta-human chorionic gonadotropin \[B-hCG\]) or urine pregnancy test at screening. Women who are pregnant or breastfeeding are ineligible for this study.

• Male patients must agree to refrain from sperm donation, from initial study drug administration until 90 days after the last dose of study drug.

⁃ Patient is able to swallow whole tablets.

⁃ Patient (or their legally acceptable representatives) must sign an informed consent document indicating that they understand the purpose of and procedures required for the study, including biomarkers, and are willing to participate in the study.