A study to determine the safety, tolerability, and anti-tumor effectiveness of an oral investigational drug in the treatment of relapsed diffuse large B-cell lymphoma.

Inclusion Criteria:

• Patient must be 18 years or older with relapsed Diffuse Large B-cell Lymphoma (DLBCL).
• Stable disease or better for at least 3 months on most recent treatment
• Have not received any chemotherapy, radiation therapy, major surgery, or any other investigational therapy for at least 4 weeks prior to entry in this study
• Adequate blood testing, liver, and kidney function as required by the study.
• Eligible subjects will allow tissue samples to be examined and stored.

Exclusion Criteria:

• Patient has been treated with other investigational agents with a similar anti-tumor mechanism.
• Patient should not have failed more than 3 prior treatment regimens.