CHOP-R + bortezomib as initial therapy for diffuse large B-cell lymphoma (DLBCL)

8031 Background: Bortezomib is a proteasome inhibitor with anti-tumor activity in B cell malignancies. These effects, which may relate to NF-kappaB associated pathways, could sensitize tumor cells to standard chemotherapy-based regimens and enhance efficacy. We report findings of a phase I/II trial of dose-escalated bortezomib + standard CHOP-rituximab in DLBCL patients (accrual of the MCL cohort of this study remains ongoing). Methods: Patients with previously untreated DLBCL (n=40) received CHOP-21 + rituximab (375 mg/m2 each cycle) plus bortezomib at 0.7 mg/m2 (Arm 0, n=4), 1.0 mg/m2 (Arm 1, n=8) or 1.3 mg/m2 (Arm 2, n=28 including phase I and all phase II) on days 1 and 4 of each cycle Results: Median age (n=40) was 58 years (range 21–86), thirty-five subjects (88%) had stage III/IV disease at study entry, and 29 (73%) had elevated serum lactate dehydrogenase (LDH). Patients generally had unfavorable baseline international prognostic index (IPI) scores of 2 in 16 subjects (40%) and 3–5 in 19 subjects (48%). Median follow-up is 21 months (range 9 - 35 months). Treatment was generally well tolerated. Peripheral neuropathy occurred in 22 subjects (55%), with 45% grade 1, 5% grade 2 and 5% grade 3. Grade 4 hematologic toxicity included thrombocytopenia (15%) and leukopenia (15%). Four subjects (3 over age 75 and all with high risk IPI) died prior to first response assessment. Intent to treat (ITT) overall response rate (n=40) is 90% with 68% CR/CRu. For the evaluable subset (n=36), ORR was 100% with CR/CRu 75%. Kaplan-Meier estimate (n=40) of 2-year progression-free survival is 72%. Of all 19 enrolled (ITT) patients in the high-intermediate or high-risk IPI groups, 14 (74%) were alive without progression at last assessment. Correlation of outcome with cell of origin type (activated B cell vs germinal center) is ongoing. Conclusions: Bortezomib can be administered with acceptable toxicity in conjunction with CHOP-R chemotherapy. Efficacy findings with this combination regimen in newly-diagnosed DLBCL are encouraging and warrant further study. No significant financial relationships to disclose.