Differential prognostic impact of GELTAMO-IPI in cell of origin subtypes of Diffuse Large B Cell Lymphoma as defined by the Hans algorithm.

The Grupo Español de Linfomas y Trasplantes de Médula Ósea International Prognostic Index (GELTAMO-IPI) stratifies four risk groups in diffuse large B cell lymphoma (DLBCL) patients treated with immunochaemotherapy: low (LR), low-intermediate (LIR), high-intermediate (HIR), and high (HR). The present study explores the effect of GELTAMO-IPI in the DLBCL subtypes defined by the immunohistochaemistry-based Hans algorithm, Germinal Centre B (GCB) and non-GCB. A multivariate Cox regression model including GELTAMO-IPI risk groups, cell of origin (COO) subtypes and their product was developed to evaluate interaction between the two variables. The COO subtype was available in 839 patients (380 GCB; 459 non-GCB) and both the GELTAMO-IPI and the COO subtype in 780 (353 GCB; 427 non-GCB). There were no differences in 5-year overall survival (OS) between the two subtypes. The Cox model revealed interaction between the GELTAMO-IPI risk groups and the COO subtypes (P = 0·005), indicating that GELTAMO-IPI has a different effect in the two subtypes. Three risk groups were stratified in both COO subtypes: in the GCB subtype, LR, LIR and the combined HIR+HR had 5-year OS of 100%, 75% and 52%, respectively. In the non-GCB subtype, LR, the combined LIR+HIR and HR had a 5-year OS of, 97%, 82% and 35% respectively. GELTAMO-IPI identifies a genuine poor outcome group of patients in the DLBCL non-GCB subtype.

Validation of the NCCN-IPI for diffuse large B-cell lymphoma (DLBCL): the addition of ß2 -microglobulin yields a more accurate GELTAMO-IPI.

The study included 1848 diffuse large B-cell lymphoma (DLBCL)patients treated with chemotherapy/rituximab. The aims were to validate the National Comprehensive Cancer Network International Prognostic Index (NCCN-IPI) and explore the effect of adding high Beta-2 microglobulin (ß2M), primary extranodal presentation and intense treatment to the NCCN-IPI variables in order to develop an improved index. Comparing survival curves, NCCN-IPI discriminated better than IPI, separating four risk groups with 5-year overall survival rates of 93%, 83%, 67% and 49%, but failing to identify a true high-risk population. For the second aim the series was split into training and validation cohorts: in the former the multivariate model identified age, lactate dehydrogenase, Eastern Cooperative Oncology Group performance status, Stage III-IV, and ß2M as independently significant, whereas the NCCN-IPI-selected extranodal sites, primary extranodal presentation and intense treatments were not. These results were confirmed in the validation cohort. The Grupo Español de Linfomas/Trasplante de Médula ósea (GELTAMO)-IPI developed here, with 7 points, significantly separated four risk groups (0, 1-3, 4 or ≥5 points) with 11%, 58%, 17% and 14% of patients, and 5-year overall survival rates of 93%, 79%, 66% and 39%, respectively. In the comparison GELTAMO IPI discriminated better than the NCCN-IPI. In conclusion, GELTAMO-IPI is more accurate than the NCCN-IPI and has statistical and practical advantages in that the better discrimination identifies an authentic high-risk group and is not influenced by primary extranodal presentation or treatments of different intensity.