MYC/BCL2 dual expresser, but not cell of origin classification, is highly prognostic of poor survival in Diffuse Large B-Cell Lymphoma patients from the RICOVER-60 and R-MegaCHOEP trials

On 19^th May 2017, in the Journal of Clinical Oncology, Annette M. Staiger from the University of Tübingen, Tübingen, Germany, and colleagues published an article which aimed to assess the prognostic impact and interdependence of the Cell-of-Origin (COO) classification, Dual Expression (DE) of MYC and BCL2, and translocations in MYC, BCL2, and BCL6 in DLBCL patients enrolled in two prospectively randomized clinical trials¹ (RICOVER-60² and R-MegaCHOEP³).

In the current analysis, formalin-fixed paraffin-embedded samples were reviewed by expert hemato-pathologists in accordance with the WHO 2008 classification.

COO classification was successfully obtained for 326/949 and 88/202 tumors in RICOVER-60 and R-MegaCHOEP, respectively. In RICOVER-60: ABC = 42% (137/326); GCB = 44% (142); unclassified = 14% (47). In R-MegaCHOEP: ABC = 27% (24/88); GCB = 60% (53); unclassified = 13% (11). The R-MegaCHOEP study enrolled significantly more GCB pts (69%; 53/77) vs. the RICOVER-60 study (51%; 149/279; P = 0.005). In RICOVER-60, more immunoblastic lymphomas were designated ABC (14/98; 14%) than GCB subtype (2/93; 2%; P = 0.002).

Key Highlights:

IHC

• RICOVER-60: GCB associated with a greater proportion of CD10+ tumors (64% vs. 10%; P < 0.001) and BCL6 (94% vs. 78%; P = 0.001) whereas BCL2 (78% vs. 50%) and IRF4/MUM1 (97% vs. 65%) were enriched in ABC-like DLBCL (P < 0.001)
• R-MegaCHOEP: GCB associated with a greater proportion of CD10+ tumors (58% vs. 13%; P < 0.001), BCL6 (64% vs. 45%; P = 0.17), and LMO2 (87% vs. 32%; P < 0.001) whereas BCL2 (96% vs. 66%; P = 0.007), IRF4/MUM1 (91% vs. 37%; P < 0.001), and FOXP1 (55% vs. 6%; P < 0.001) were enriched in ABC-like DLBCL
• The proportion of DLBCLs that expressed MYC was higher in the ABC group, especially in the R-MegaCHOEP trial (50% vs. 26%; P = 0.06)
• A greater number of DLBCLs with DE were in the ABC group:
  • RICOVER-60: ABC = 33/99 [33%]; GCB = 16/93 [17%]; P = 0.01
  • R-Mega-CHOEP: ABC = 10/22 [46%]; GCB = 6/35 [17%]; P = 0.02

FISH

• In RICOVER-60:
  • BCL2 translocations were exclusively observed in GCB-like DLBCL (P < 0.001)
  • MYC breaks clustered in GCB-like DLBCL (14% vs. 3% in ABC; P = 0.005)
  • BCL6 breaks were equally distributed between ABC (33%) and GCB (29%) types
  • All 9 MYC/BCL2 Double-Hit (DH) pts were GCB-like DLBCL (9% of GCB; P = 0.001)
  • The 3 MYC/BCL6 DH lymphomas were equally distributed in the GCB, ABC, and unclassified groups
• In R-MegaCHOEP:
  • BCL2 translocations were enriched in GCB (11/42; 26%) vs. ABC (1/23; 4%; P = 0.04)
  • BCL6 translocations were more common in ABC (48%) vs. GCB (17%; P = 0.007)
  • All 4 MYC/BCL2 DH lymphomas and 1 triple-hit lymphoma (MYC/BCL2/BCL6) were GCB
  • One MYC/BCL6 DH lymphoma was ABC and one other was GCB

Survival

• In R-MegaCHOEP:
  • No survival differences were observed between ABC and GCB-like DLBCL
• In RICOVER-60:
  • ABC had inferior EFS vs. GCB in the entire cohort (HR, 1.4; 95% CI, 1.0–1.9; P = 0.04) and in CHOP-14 treated pts (HR, 1.6; 95% CI, 1.0–2.4; P = 0.05)
  • ABC had inferior PFS vs. GCB in the entire cohort (HR, 1.5; 95% CI, 1.1–2.1; P = 0.02) and in CHOP-14 treated pts (HR, 1.6; 95% CI, 1.0–2.5; P = .05)
  • ABC had inferior OS vs. GCB in the entire cohort (HR, 1.5; 95% CI, 1.0–2.1; P = 0.04) and in CHOP-14 treated pts (HR, 1.7; 95% CI, 1.0–2.8; P = 0.05)
  • No significant differences between ABC and GCB in EFS (HR, 1.2; 95% CI, 0.8–2.0; P = 0.36), PFS (HR, 1.4; 95% CI, 0.8–2.3; P = 0.21), or OS (HR, 1.3; 95% CI, 0.8–2.2; P = 0.36) found in R-CHOP treated pts
• In RICOVER-60 R-CHOP-treated pts:
  • MYC expression identified pts with inferior EFS, PFS, and OS among GCB-like DLBCL (P = 0.001, P = 0.001, and P = 0.002, respectively)
  • Only a trend toward inferior EFS was found in ABC-like DLBCL (P = 0.08)
  • BCL2 expression trended toward inferior outcome in GCB but not ABC-like DLBCL
  • Pts with DE status had significantly inferior EFS, PFS, and OS in GCB-like DLBCL vs. non-expressers (P < 0.001 each) and with BCL2 expressers only (P < 0.001, P = 0.003, and P = 0.004, respectively); these results did not occur in the ABC group
  • When MYC/BCL2 DH pts were removed from analysis, a non-significant trend for inferior survival in DE vs. non-DE was observed in GCB-like DLBCL
  • Among GCB and ABC pts who did not have MYC/BCL2 DH or triple-hit status, significantly inferior OS was observed for pts with DE (P = 0.03)
  • When DE pts were removed from analysis, ABC pts had inferior outcome vs. GCB:
    • 5-year EFS: 65% (95% CI, 48–82%) vs. 80% (95% CI, 68–92%; P = 0.06)
    • 5-year PFS: 68% (95% CI, 52–85%) vs. 85% (95% CI, 74–96%; P = 0.04)
    • 5-year OS: 75% (95% CI, 60–90%) vs. 88% (95% CI, 77–98%; P = 0.12)
  • MYC/BCL2 DEs had significantly shorter survival vs. pts in the ABC group without DE:
    • 5-year EFS: 34% (95% CI, 15–52%) vs. 65% (95% CI, 48–82%; P = 0.02)
    • 5-year PFS: 39% (95% CI, 19–59%) vs. 68% (95% CI, 52–85%; P = 0.03)
    • 5-year OS; 42% (95% CI, 22–62%) vs. 75% (95% CI, 60–90%; P = 0.008)
  • No significant difference in EFS, PFS, or OS was found between ABC and GCB groups without MYC/BCL2 DE
  • Presence of MYC breaks predicted significantly inferior EFS, PFS, and OS in GCB group pts

The authors stated that their paper is the first, to their knowledge, FFPE study on gene expression-based COO profiling of prospective, randomized trials. They concluded that COO profiling alone failed to identify prognostic subgroups. However, “MYC/BCL2 DE status was highly prognostic of poor survival.”

Abstract:

Purpose: To explore the prognostic impact and interdependence of the cell-of-origin (COO) classification, dual expression (DE) of MYC and BCL2 proteins, and MYC, BCL2, and BCL6 translocations in two prospectively randomized clinical trials of patients with diffuse large B-cell lymphoma (DLBCL).

Patients and Methods: Overall, 452 formalin-fixed paraffin-embedded samples from two prospective, randomized DLBCL trials (RICOVER-60, prospective, randomized study for patients > 60 years, all IPI groups; and R-MegaCHOEP, prospective, randomized study for patients ≤ 60 years with age-adjusted IPI 2,3) of the German High-Grade Non-Hodgkin Lymphoma Study Group were analyzed with the Lymph2Cx assay for COO classification, with immunohistochemistry for MYC and BCL2, and with fluorescent in situ hybridization for MYC, BCL2, and BCL6 rearrangements.

Results: COO classification was successful in 414 of 452 samples. No significant differences with respect to COO (activated B-cell [ABC]-like DLBCL v germinal center B-cell [GCB]-like DLBCL) were observed in event-free survival, progression-free survival, and overall survival in patients treated with rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) in the RICOVER-60 trial. Also, no differences with respect to COO were observed in multivariable analyses adjusted for International Prognostic Index factors in event-free survival (hazard ratio [HR] of ABC-like disease v GCB-like disease, 1.0; 95% CI, 0.6 to 1.6; P = .93), progression-free survival (HR, 1.1; 95% CI, 0.6 to 1.8; P = .82), and overall survival (HR, 1.0; 95% CI, 0.6 to 1.8; P = .96). Similar results were observed in the R-MegaCHOEP trial. In patients treated with R-CHOP, DE status was associated with significantly inferior survival compared with nonDE within the GCB, but not within the ABC subgroup. DE status was associated with significantly inferior outcome compared with patients with ABC-like DLBCL without DE (5-year PFS rate, 39% [95% CI,19% to 59%] v 68% [95% CI, 52% to 85%]; P = .03) and compared with patients with GCB-like DLBCL without DE. When data from patients with nonDE were analyzed separately, the outcome of patients in the ABC subgroup was inferior to that of patients in the GCB subgroup (5-year PFS rate, 68% [95% CI, 52% to 85%] v 85% [95% CI, 74% to 96%]; P = .04).

Conclusion: COO profiling in two prospective randomized DLBCL trials failed to identify prognostic subgroups, whereas dual expression of MYC and BCL2 was predictive of poor survival. Evaluation of prognostic or predictive biomarkers in the management of DLBCL, such as the COO, within prospective clinical trials will be important in the future.