No Benefit from Rituximab Containing Regimens in Patients with Primary Extranodal Diffuse Large B-Cell Lymphoma
Authors: Gutiérrez-García Gonzalo , Colomo Luis , Villamor Neus , Arenillas Leonor , Martínez Antonio , Camós Mireia , Diaz-Beyá Marina , de Larrea Carlos Fernández , Calvo Xavier , Giné Eva , Bosch Francesc , Campo Elias , Montserrat Emili , López-Guillermo Armando 
Published: October 2019

Diffuse large B-cell lymphoma (DLBCL) is a heterogeneous category of lymphoid tumors that comprises different clinical forms not fully recognized in the WHO classification. In this regard, extranodal (EN) DLBCLs have particular clinicobiological features and outcome, sometimes related to the specific site where the lymphoma arises. Nowadays, rituximab plus chemotherapy (CT) is the gold-standard in the treatment of DLBCL. However, the superiority of rituximab-CT (R-CT) over CT alone has not been addressed for all the clinical subsets of the disease and, in fact, the clinical role of the new therapies might be different for primary nodal or EN DLBCLs. The aim of this study was to assess the impact of rituximab in patients suffering from nodal or EN DLBCL. Two-hundred and thirty non-immunocompromised patients (112M/118F; median age, 61 years) diagnosed with CD20+DLBCL in a single institution between 1997 and 2006 (five years before and after establishing R-CT as the standard treatment in DLBCL) and treated with adriamycin-containing regimens were the subject of the present study. The series included 148 primary nodal and 82 EN DLBCL. Patients with primary CNS lymphoma were excluded and lymphomas arising at Waldeyer ring were considered as nodal DLBCL. The main EN sites were GI (n=26), bone (n=13), soft tissue (n=13), lung/pleura (n=9), liver (n=9), and other (n=12). Main clinico-biological and evolutive variables were analyzed. One hundred nineteen patients received only CT and 111 R-CT. Eighty-seven cases with available information were assigned to germinal center B-cell-like (GCB) (41%) or non-GCB (59%) groups according to the Hans method (Blood2004;103:275–82) based on CD10, BCL6 and MUM1 expression. Main initial features, including the primary nodal or EN origin, international prognostic index (IPI), and GCB/non-GCB categories were similar for CT and R-CT groups. No correlation was observed between the GCB/non-GCB groups and the primary site of the tumor, although nodal lymphomas more frequently expressed MUM1 than EN (69% vs. 31%, respectively; p=0.01). CR rate and 5-year overall survival (OS) according to the treatment arm (CT vs. R-CT) is detailed for the whole series and for the nodal and EN groups in the table and OS curves depicted in the figure. In the whole series, variables predicting poor OS in the multivariate analysis were high-risk IPI (RR 2.5; p<0.001), primary nodal involvement (RR 1.6; p=0.04) and no R-CT treatment (RR 1.9; p=0.002). In the nodal group, IPI and no R-CT maintained the prognostic value, whereas in the primary EN only IPI predicted OS. Moreover, no difference in OS was observed according to the nodal or EN origin in those patients receiving R-CT. Biological subtypes GCB vs. non-GCB did not add predictive information neither in the whole series nor in the nodal or EN groups. In conclusion, patients with primary EN DLBCL seem to have little benefit from the use of R-CT. Nevertheless, this intriguing observation should be confirmed in further prospective studies.

Complete response CR (%) 5-years OS (%) CT R-CT CT R-CT *p<0.002 R-CT vs. CT All cases (n=230) 59 79* 46 70* Primary nodal (n=148) 54 78* 34 71* Primary extranodal (n=82) 68 78 70 69

Figure Figure