Double-Hit and Double-Expressor Lymphomas Are Not Associated with an Adverse Outcome after Allogeneic Stem Cell Transplantation

Background: Double-hit lymphomas (DHL) - diffuse large B-cell lymphomas (DLBCL) with concurrent rearrangements of MYC and BCL2 and/or BCL6, and double-expressor lymphomas (DEL) - DLBCL with co-expression of MYC and BCL2 by immunohistochemistry (IHC), are associated with poor outcomes after standard chemoimmunotherapy. We have previously demonstrated that patients with relapsed or refractory (rel/ref) DHL and DEL have inferior outcomes after autologous stem cell transplantation (autoSCT) compared to patients with neither DEL nor DHL [Herrera et al, ASH 2015]. Although patients with DEL and DHL have inferior outcomes after chemotherapy-based treatment modalities, we hypothesized that allogeneic SCT (alloSCT) could potentially abrogate that negative prognostic impact. Data are extremely limited regarding the outcome of patients with DHL who undergo alloSCT, and no study has examined alloSCT outcomes in patients with DEL. We studied alloSCT outcomes in a multicenter cohort of rel/ref DLBCL patients and evaluated the prognostic impact of DEL and DHL status.

Methods: We retrospectively studied patients with rel/ref DLBCL, transformed indolent lymphoma (TIL), or high-grade B-cell lymphoma unclassified (BCLU) who had available tumor tissue and underwent alloSCT at Dana-Farber Cancer Institute, Massachusetts General Hospital, or City of Hope between 1/2000 and 5/2014. IHC for MYC, BCL2, and BCL6 were performed. DEL was defined as MYC expression in ≥ 40% tumor cells and BCL2 expression in ≥ 50% tumor cells. FISH for MYC was performed using dual-color break-apart probes. Cases with MYC-rearrangement had FISH performed for BCL2 and BCL6 using break-apart probes. Rearrangement was defined as ≥ 10% nuclei with break-apart signals. DHL was defined as concurrent rearrangement of MYC and BCL2 and/or BCL6.

Results: Tumor tissue was available in 103 patients, among whom we could obtain complete IHC and FISH data in 74. In these 74 patients, the median age was 54 years (range 24-69); 69% had DLBCL/BCLU whereas 31% had TIL; the median number of prior therapies was 4 (range 2-9); 58% had prior autoSCT; 73% were in complete or partial remission (CR/PR) at alloSCT; 77% had reduced intensity conditioning (RIC); 78% had a matched related or unrelated donor. 4y progression-free survival (PFS), overall survival (OS), cumulative incidence of relapse (CIR), and non-relapse mortality (NRM) in the overall cohort were 34%, 40%, 44% and 22%, respectively, with a median follow-up of 46 months for survivors.

47% of patients had DEL and 14% had DHL. The proportion of patients with a history of primary refractory disease was higher among DHL (60%) and DEL (52%) patients compared to nonDHL/nonDEL patients (37%), although the difference was not significant (p=0.3). Overall, there were no significant differences in clinical characteristics between patients with DHL, DEL, and nonDHL/nonDEL.

Neither DEL nor DHL were significantly associated with outcome (Figure). The 4y PFS in DEL v non-DEL patients was 29% v 39% (p=0.2), 4y OS 30% v 49% (p=0.11), 4y CIR 50% v 40% (p=0.3), and 4y NRM 21% v 22% (p=1.0). The 4y PFS in DHL v non-DHL patients was 40% v 33% (p=0.6), OS 50% v 37% (p=0.4), CIR 40% v 45% (p=0.9), and NRM 20% v 22% (p=0.8).

In multivariable Cox models for PFS and OS, age ≥ 55 (PFS: HR 0.4, p=0.002; OS: HR 0.4, p=0.005), refractory disease (not CR/PR) at alloSCT (PFS: HR 2.4, p=0.009; OS HR 2.6, p=0.007), and TIL (PFS HR 0.4, p=0.018; OS HR 0.4, p=0.028) were associated with PFS and OS, but DEL (PFS HR 1.2, p=0.5; OS HR 1.6, p=0.12) and DHL (PFS HR 0.8, p=0.7; OS HR 0.8, p=0.7) were not. We also constructed multivariable competing risk regression models for CIR and NRM. Age, remission status, histology, and conditioning intensity were associated with relapse, while no factor was significantly associated with NRM. Neither DEL (CIR HR 1.2, p=0.7, NRM HR 0.8, p=0.7) nor DHL (CIR HR 1.1, p=0.9, NRM HR 0.8, p=0.8) were associated with either outcome in those models.

Conclusions: AlloSCT produced durable remissions in heavily treated rel/ref DLBCL patients, regardless of DEL and DHL status. In our cohort, DEL and DHL status did not have a significant prognostic impact. Although patients with DEL or DHL have poorer outcomes after chemoimmunotherapy and autoSCT, our results suggest that alloSCT may overcome the chemoresistance of double-hit/double-expressor tumors.

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Progression-Free Survival After AlloSCT in DEL, DHL, and nonDEL/nonDHL Patients

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Progression-Free Survival After AlloSCT in DEL, DHL, and nonDEL/nonDHL Patients

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