Inclusion Criteria:

          -  Men and women ≥ 18 years of age

          -  Diagnosis of mantle cell lymphoma established by histologic assessment by a
             hemato-pathologist with additional assessment of the histologic diagnosis by
             immunohistochemistry or flow cytometry.

          -  Patients with history of MCL that has relapsed (documented disease progression after
             previously responding) to therapy (CR/PR) on single agent ibrutinib (treated for at
             least 6 months) as the last treatment prior to enrollment.

          -  Adequate liver, renal and bone marrow function

          -  Adequate coagulation (unless abnormalities are unrelated to coagulopathy or bleeding
             disorder)

          -  Female subjects of childbearing potential must have a negative urine/serum pregnancy
             test upon study entry. Women as well are not advised to breastfeed during treatment
             with bortezomib and for 2 months after treatment.

          -  Male and female subjects of reproductive potential must agree to use both a highly
             effective method of birth control and barrier method during the period of therapy and
             for 30 days after the last dose of study drug for females and 90 days for males.

          -  Eastern Cooperative Oncology Group (ECOG) performance status of <2 (Eastern
             Cooperative Oncology Group scoring system used to quantify general well-being and
             activities of daily life; scores range from 0 to 5 where 0 represents perfect health
             and 5 represents death.)

        Exclusion Criteria:

          -  Concurrent diagnosis of another malignancy unless treated with curative intent more
             than 2 years from study start (basal/squamous cell carcinoma of the skin is not an
             exclusion).

          -  Previous treatment with bortezomib.

          -  Patients who are eligible for autologous stem cell transplant are excluded unless they
             refuse this procedure.

          -  History of allogeneic stem cell transplant.

          -  Other exclusions (certain concurrent conditions) per protocol