High-grade B-cell lymphoma, not otherwise specified: a multi-institutional retrospective study.

In this multi-institutional retrospective study, we examined characteristics and outcomes of 160 patients with high-grade B-cell lymphoma, not otherwise specified (HGBL-NOS). This rare lymphoma category is defined by high-grade morphologic features, most commonly Burkitt-like, and lack of MYC rearrangements with BCL2 and/or BCL6 rearrangements (so-called double-hit). Our results show that HGBL-NOS tumors are heterogeneous: 83% had a germinal center B-cell immunophenotype, 37% a dual expressor immunophenotype (MYC and BCL2 expression), 28% (single-hit) MYC rearrangement, 13% BCL2 rearrangement, and 11% BCL6 rearrangement. Most patients presented with stage 4 disease, a high serum lactate dehydrogenase, and other high-risk clinical factors. Most frequent first-line regimens included DA-EPOCH-R (43%), R-CHOP (33%), or other intensive chemotherapy programs (11%). We found no significant differences in the rates of complete response (CR, P=0.32), progression-free (PFS, P=0.82), or overall survival (OS, P=0.60) between these chemotherapy regimens. CR was attained by 69% of patients. PFS at 2 years was 55.2% (95%CI, 46.9-62.7), and OS was 68.1% (95%CI, 59.7-75.0). In a multivariable model, the main prognostic factors for PFS and OS were poor performance status, lactate dehydrogenase >3x upper limit of normal, and a dual expressor immunophenotype. Age >60 years or presence of MYC rearrangement were not prognostic, but patients with TP53 alterations had a dismal PFS (13% at 2 years). Presence of MYC rearrangement was not predictive of better PFS in patients treated with DA-EPOCH-R versus R-CHOP. Improvements in the diagnostic criteria and therapeutic approaches beyond dose-intense chemotherapy are needed to overcome the unfavorable prognosis of patients with HGBL-NOS.