Phase II study of dose-adjusted EPOCH and rituximab in untreated diffuse large B-cell lymphoma with analysis of germinal center and post-germinal center biomarkers

Abstract

Purpose: To assess the clinical outcome and the influence of biomarkers associated with apoptosis inhibition (Bcl-2), tumor proliferation (MIB-1), and cellular differentiation on the outcome with dose-adjusted (DA) EPOCH (etoposide, prednisone, vincristine, cyclophosphamide, and doxorubicin) plus rituximab (R) infusional therapy in diffuse large B-cell lymphoma (DLBCL) with analysis of germinal center B-cell (GCB) and post-GCB subtypes by immunohistochemistry.

Patients and methods: Phase II study of 72 patients with untreated de novo DLBCL who were at least 18 years of age and stage II or higher. Radiation consolidation was not permitted.

Results: Patients had a median age of 50 years (range, 19 to 85) and 40% had a high-intermediate or high International Prognostic Index (IPI). At 5 years, progression-free survival (PFS) and overall survival (OS) were 79% and 80%, respectively, with a median potential follow-up of 54 months. PFS was 91%, 90%, 67%, and 47%, and OS was 100%, 90%, 74%, and 37%, for 0 to 1, 2, 3, and 4 to 5 IPI factors, respectively, at 5 years. The Bcl-2 and MIB-1 biomarkers were not associated with PFS or OS. Based on DA-EPOCH historical controls, rituximab only benefited Bcl-2 positive tumors. Bcl-6 expression was associated with higher PFS whereas GCB exhibited a marginally significant higher PFS compared with post-GCB DLBCL.

Conclusion: DA-EPOCH-R outcome was not affected by tumor proliferation and rituximab appeared to overcome the adverse effect of Bcl-2. Bcl-6 may identify a biologic program associated with a superior outcome. Overall, DA-EPOCH-R shows promising outcome in low and intermediate IPI groups. A molecular model of treatment outcome with rituximab and chemotherapy is presented.

Figure 1

Survival and Progression-Free Survival of All Patients. Outcomes are reported at five years (95% Confidence Interval (CI)). (A) Progression-free survival (PFS) 79% (68, 87). (B) Overall survival (OS) 80% (69, 88). (C) PFS for low, low-intermediate, high-intermediate and high risk IPI 91% (72, 98), 90% (71, 97), 67% (42, 85) and 47% (21, 75), respectively (p = 0.007 for global comparison). (D) OS for low, low-intermediate, high-intermediate and high risk IPI 100%, 90% (70, 97), 74% (50, 90) and 37% (16, 64), respectively (p < 0.0001 for global comparison).

Figure 1

Survival and Progression-Free Survival of All Patients. Outcomes are reported at five years (95% Confidence Interval (CI)). (A) Progression-free survival (PFS) 79% (68, 87). (B) Overall survival (OS) 80% (69, 88). (C) PFS for low, low-intermediate, high-intermediate and high risk IPI 91% (72, 98), 90% (71, 97), 67% (42, 85) and 47% (21, 75), respectively (p = 0.007 for global comparison). (D) OS for low, low-intermediate, high-intermediate and high risk IPI 100%, 90% (70, 97), 74% (50, 90) and 37% (16, 64), respectively (p < 0.0001 for global comparison).

Figure 1

Survival and Progression-Free Survival of All Patients. Outcomes are reported at five years (95% Confidence Interval (CI)). (A) Progression-free survival (PFS) 79% (68, 87). (B) Overall survival (OS) 80% (69, 88). (C) PFS for low, low-intermediate, high-intermediate and high risk IPI 91% (72, 98), 90% (71, 97), 67% (42, 85) and 47% (21, 75), respectively (p = 0.007 for global comparison). (D) OS for low, low-intermediate, high-intermediate and high risk IPI 100%, 90% (70, 97), 74% (50, 90) and 37% (16, 64), respectively (p < 0.0001 for global comparison).

Figure 2

Progression-Free Survival of Patients with Biomarkers. Outcomes are reported at five years. (A) PFS for MIB-1 < 80% and ≥ 80% in DA-EPOCH-R. (B) PFS for Bcl-2 negative and positive patients following DA-EPOCH (PFS at 5 years: Bcl-2 negative 82% (59, 94) vs. positive 50% (25, 75); p = 0.03). Exclusion of PMBL patients from this historical cohort did not significantly alter the balance of IPI factors or PFS at 5 years (Bcl-2 negative 91% (62, 98) vs. positive 57% (25, 84); p = 0.039). (C) PFS for Bcl-2 negative and Bcl-2 positive, for DA-EPOCH-R. (D) PFS for GCB versus post-GCB for DA-EPOCH-R (E) PFS for Bcl-6 negative and Bcl-6 positive, respectively, for DA-EPOCH-R.

Figure 2

Progression-Free Survival of Patients with Biomarkers. Outcomes are reported at five years. (A) PFS for MIB-1 < 80% and ≥ 80% in DA-EPOCH-R. (B) PFS for Bcl-2 negative and positive patients following DA-EPOCH (PFS at 5 years: Bcl-2 negative 82% (59, 94) vs. positive 50% (25, 75); p = 0.03). Exclusion of PMBL patients from this historical cohort did not significantly alter the balance of IPI factors or PFS at 5 years (Bcl-2 negative 91% (62, 98) vs. positive 57% (25, 84); p = 0.039). (C) PFS for Bcl-2 negative and Bcl-2 positive, for DA-EPOCH-R. (D) PFS for GCB versus post-GCB for DA-EPOCH-R (E) PFS for Bcl-6 negative and Bcl-6 positive, respectively, for DA-EPOCH-R.

Figure 2

Progression-Free Survival of Patients with Biomarkers. Outcomes are reported at five years. (A) PFS for MIB-1 < 80% and ≥ 80% in DA-EPOCH-R. (B) PFS for Bcl-2 negative and positive patients following DA-EPOCH (PFS at 5 years: Bcl-2 negative 82% (59, 94) vs. positive 50% (25, 75); p = 0.03). Exclusion of PMBL patients from this historical cohort did not significantly alter the balance of IPI factors or PFS at 5 years (Bcl-2 negative 91% (62, 98) vs. positive 57% (25, 84); p = 0.039). (C) PFS for Bcl-2 negative and Bcl-2 positive, for DA-EPOCH-R. (D) PFS for GCB versus post-GCB for DA-EPOCH-R (E) PFS for Bcl-6 negative and Bcl-6 positive, respectively, for DA-EPOCH-R.

Figure 2

Progression-Free Survival of Patients with Biomarkers. Outcomes are reported at five years. (A) PFS for MIB-1 < 80% and ≥ 80% in DA-EPOCH-R. (B) PFS for Bcl-2 negative and positive patients following DA-EPOCH (PFS at 5 years: Bcl-2 negative 82% (59, 94) vs. positive 50% (25, 75); p = 0.03). Exclusion of PMBL patients from this historical cohort did not significantly alter the balance of IPI factors or PFS at 5 years (Bcl-2 negative 91% (62, 98) vs. positive 57% (25, 84); p = 0.039). (C) PFS for Bcl-2 negative and Bcl-2 positive, for DA-EPOCH-R. (D) PFS for GCB versus post-GCB for DA-EPOCH-R (E) PFS for Bcl-6 negative and Bcl-6 positive, respectively, for DA-EPOCH-R.

Figure 2

Progression-Free Survival of Patients with Biomarkers. Outcomes are reported at five years. (A) PFS for MIB-1 < 80% and ≥ 80% in DA-EPOCH-R. (B) PFS for Bcl-2 negative and positive patients following DA-EPOCH (PFS at 5 years: Bcl-2 negative 82% (59, 94) vs. positive 50% (25, 75); p = 0.03). Exclusion of PMBL patients from this historical cohort did not significantly alter the balance of IPI factors or PFS at 5 years (Bcl-2 negative 91% (62, 98) vs. positive 57% (25, 84); p = 0.039). (C) PFS for Bcl-2 negative and Bcl-2 positive, for DA-EPOCH-R. (D) PFS for GCB versus post-GCB for DA-EPOCH-R (E) PFS for Bcl-6 negative and Bcl-6 positive, respectively, for DA-EPOCH-R.

Figure 3

Model of drug resistance in GCB and post-GCB DLBCL. In germinal center B-cells, Bcl-6 encodes a transcriptional repressor which negatively regulates the cell cycle inhibitors p21 and p27Kip1 and promotes proliferation. Bcl-6 also suppresses the p53 tumor suppressor gene and ATM, and modulates DNA damage induced apoptosis. Constitutive activation of NF-κB, a transcriptional regulator, in post-germinal center B-cells increases Bcl-2 and A1 and increases the apoptotic threshold. Clinical evidence that rituximab primarily benefits post-GCB DLBCL and inhibits NF-κB in vitro suggests rituximab modulates post-GCB DLBCL drug resistance. In GCB DLBCL, topoisomerase inhibitors can differentially activate DNA damage checkpoints and may be selectively important. Theoretical relative cytotoxic responses [high to low: of rituximab, and CHOP and DA-EPOCH with and without rituximab along the continuum from germinal center to post-germinal center DLBCL are shown. Rituximab benefit is primarily in post-GCB DLBCL where it modulates drug resistance and “equalizes” differences among chemotherapy regimens. In GCB DLBCL, DA-EPOCH-R may show an advantage in part due to extended delivery of topoisomerase II agents.