Inclusion Criteria:

Patients must:

1. Have a histologically confirmed diagnosis of DLBCL based on the World Health
Organization classification (Harris et al. 1999) at the time of original diagnosis.
Pathology must be reviewed and confirmed prior to enrollment at the investigational
site where the patient is entered. Patients with a prior history of an indolent
lymphoma or a histological diagnosis of follicular Grade 3 lymphoma will not be
eligible for enrollment.

2. Have received no prior chemotherapy.

3. Have an IPI score > or = to 2 at time of original diagnosis.

4. Have a performance status of 0, 1, or 2 on the Eastern Cooperative Oncology group
(ECOG) scale.

5. Have adequate organ function as follows:

- Hepatic: total bilirubin < or = to 1.5 times the upper limit of normal (X ULN);
alanine transaminase (ALT) and aspartate transaminase (AST) < or = to 1.5 X ULN,
(≤5 X ULN, if liver involvement).

- Renal: serum creatinine < or = to 1.5 X ULN

- Adequate bone marrow reserve: platelets > or = to 75 X 10 to the ninth/L,
absolute neutrophil count (ANC) > or = to 1.0 X 10 to the ninth/L, unless there
is bone marrow involvement.

Exclusion Criteria:

Patients must not:

6. Have received treatment within the last 30 days with a drug (not including
enzastaurin) that has not received regulatory approval for any indication at the time
of study entry.

7. Are receiving concurrent administration of any other systemic anticancer therapy.

8. Are pregnant or breastfeeding.

9. Are unable to swallow tablets.

10. Are unable to discontinue use of carbamazepine, phenobarbital, and phenytoin at least
14 days prior to study enrollment.