Risk Adapted-High Dose Therapies Modulate the Impact of Biological Classification in Diffuse Large B Cell Lymphoma Prognosis. Analysis of Biological Markers in Patients From Clinical Trials in Geltamo and Gotel Spanish Collaborative Groups.

Several molecular markers are now available for prognostic stratification in patients with DLBCL. Cell of Origin classification based on immunohistochemistry (IHC), microRNA expression and Fluorescent In situ Hybridization (FISH) analysis for C-MYC, and BCL2 traslocations have been demonstrated to provide relevant prognostic information in patients treated with conventional chemoiimunotherapy (R-CHOP and R-CHOP-like) regimens. However, few studies have tried to validate these results in cohorts of patients treated with high dose regimens adapted to the clinical risk.

Here we have performed a comprehensive biological analysis of a series of 157 patients enrolled in 4 clinical trials from GELTAMO and GOTEL Spanish Collaborative Groups. Patients were treated with first-line high dose regimens (R-CHOP 14: 76 patients; dose-adjusted EPOCH-R: 42 patients and MegaCHOP-R and bone marrow transplantation: 39 patients) according to pre-treatment clinical risk based on IPI score. Centralized review of the histopathological diagnosis and laboratory tests were performed in a single institution. All tests were determined in the FFPE diagnostic sample. We have analyzed the clinical impact on outcome (OS and PFS) of the Cell of Origin Classification based on IHC (using Hans, Choi and Visco-Young algorithms), the presence of MYC, BCL2 and BCL6 translocations by FISH and previously defined microRNA expression signatures based on RT-PCR (Montes-Moreno et al, Blood 2011). A retrospective series of 240 R-CHOP 21 treated DLBCL cases was used for comparison.

OS and PFS at the median follow-up time (60 months) were 84 % (±3,4%) and 79% (±3,5%). No significant differences were found in OS and PFS according to the study protocol. Among the clinical parameters included in IPI score, only advanced age (>60 years) was predictive of poor OS and PFS in the univariant analysis (p <0.05). IPI risk stratification showed a trend for statistical significance for PFS (p 0.052). Significant differences in the distribution of GCB and NON-GC/ABC cases were found according to the classification method with percentages of GCB cases ranging from 41 to 52% and NONGC/ABC cases from 40 to 52% (χ2<0.001). However, none of the immunohistochemical algorithms was predictive for OS nor PFS in the whole series nor after protocol stratification. Interestingly ABC type DLBCL prognosis was significantly improved in this series when compared with the R-CHOP 21 treated control cohort (p <0.005), while GCB type DLBCL prognosis was not altered. By FISH, 6 cases (3, 8%), 19 (12,1%) and 27 (17,2%) of the evaluable cases had MYC, BCL2 and BCL6 translocations respectively. Only 3 cases of double hit lymphoma were found (1 with MYC snd BCL2 translocations, 2 cases with MYC and BCL6 translocations). None of these genetic alterations was predictive for OS nor PFS.

Among the biological markers here analyzed, only miRNA expression signatures were found of prognostic value for OS and PFS and independent in the multivariant analysis with age (Relative Risk for miRNAs 3.41 and 2.47 for OS and PFS respectively, compared to 3.20 and 3.02 for advanced age, p < 0,05).

The prognostic impact of specific biological factors in DLBCL is dependent on the therapeutic regimen. Risk adapted-high dose protocols abolish the prognostic effect of the Cell Of Origin classification as determined by immunohistochemistry with recently developed algorithms. Genetic alterations in CMYC, BCL2 and BCL6 are rare and carry no prognostic information in this series of patients. Only age and microRNA expression signatures add prognostic information in patients with DLBCL treated with risk-adapted high dose regimens.

No relevant conflicts of interest to declare.