non-GCB Patients Research Articles

Addition of rituximab to a CEOP regimen improved the outcome in the treatment of non-germinal center immunophenotype diffuse large B cell lymphoma cells with high Bcl-2 expression

Diffuse large B cell lymphoma (DLBCL) cells can be sub-classified into germinal center B cells (GCB) and non-GCB immunophenotypes. In the present study, we treated 161 newly diagnosed DLBCL patients with cyclophosphamide, epirubicin, vincristine, and prednisolone (CEOP) regimen with or without rituximab, and retrospectively investigated DLBCL sub-classifications combined with assessment of B cell lymphoma 2 (Bcl-2) expression level for their utility in the prediction of clinical efficacy. Survival analyses showed that non-GCB patients treated with R-CEOP regimen had significantly higher 5-year OS rates than the CEOP group (P = 0.033), while no statistically significant difference was observed between R-CEOP and CEOP treatments in GCB patients (P = 0.317). Prognosis was poorest for high Bcl-2 expressing non-GCB subgroup patients treated with CEOP, compared with Bcl-2 negative non-GCB CEOP patients (P = 0.044). In the R-CEOP group, Bcl-2 expression had no significant effect on prognosis for both GCB and non-GCB patients. The addition of rituximab to CEOP chemotherapy negates the adverse prognostic influence of Bcl-2 protein expression on overall survival in non-GCB DLBCL.

Outcomes Following Autologous Stem Cell Transplantation (ASCT) In Patients With Germinal Center B (GCB) and Non-GCB Cell-Like Diffuse Large B Cell Lymphomas (DLBCL) According To Conditioning With BEAM-Rituximab (Standard vs. High-Dose) Vs. BEAM/Yttrium-90 Ibritumomab Tiuxetan (90YIT)

BackgroundPatients with a DLBCL of GCB immunophenotype have a higher chance of cure than patients with non-GCB DLBCL when treated with conventional chemotherapy. In the relapsed/refractory setting, there are conflicting data regarding the impact of cell-of-origin classification on survival following ASCT. The addition of high-dose rituximab (HDR) (1000 mg /m2 days +1 and +8 after ASCT) has been shown to improve results for patients with relapsed DLBCL who undergo transplantation (Khouri et al, J Clin Oncol 2005;23:2240-7). The optimal rituximab dose to be used with ASCT [HDR vs. standard dose (SDR) 375 mg/m2 days +1 and +8)] has been under investigation at our center. More recently, we and others reported on the safety of incorporating 90YIT (0.4 mCi/Kg) in the conditioning. Herein, we compare outcomes of patients with GCB and non-GCB DLBCL after ASCT according to the conditioning regimen received. Methods and patients121 de novo DLBCL patients were treated on 4 consecutive trials between 2000 and 2012. We determined the cell-of-origin, based upon the Visco/Young and Choi immunohistochemical algorithms, and classified 64 (53%) as GCB and 57 (47%) as non-GCB tumors. Median age, gender distribution, remission status (CR vs PR), # of prior therapies, IPI, beta-2 microglobulin and LDH distribution were similar in both groups. Patients were staged with CT, PET (whenever indicated) scans and bone marrow biopsies, every 3 months for the first year, every 6 months x 5 years, then yearly thereafter. Patients received BEAM conditioning with either SDR [GCB (n =14), non-GCB (n=7), HDR [GCB (n =31), non-GCB (n=40) or 90YIT[GCB (n =19), non-GCB (n=10)]. ResultsDeterminants for progression (cell-of-origin, age, and gender, and disease status, # of prior therapies, IPI, beta-2 microglobulin and LDH distribution) were studied within each type of conditioning. Within the BEAM-SDR group, the cell-of-origin was the only significant predictor for relapse at 3-years (86% in non-GCB vs. 14% in GCB; P=0.01) (Figure), resulting in improved OS and PFS for the GCB group (both 71% vs 14%, respectively, P=0.06 for OS and 0.04 for PFS). Non-relapse mortality was 0% in this group. Within the BEAM-HDR and BEAM-90YIT groups, GCB and non-GCB patients had a similar rate of relapse (30% vs. 38%, respectively at 3-year, P=0.4) and similar 3-year PFS rates 66% vs 56%, P=0.3), and 3-year OS of 77% vs. 61% (P=0.09). [Display omitted] ConclusionOur results suggest similar outcomes for patients with DLBCL of GCB and non-GCB immunophenotype when either HDR or 90YIT is added to the BEAM conditioning. A SDR has been found to be associated with a significantly higher risk of progression and inferior survival in non-GCB patients. Disclosures:Khouri:Spectrum Pharmaceuticals: Consultancy, Research Funding. Off Label Use: Rituximab and ibritumomab tiuxetan for stem cell transplant.

Prognostic value of maximum standard uptake on pretreatment 18F-FDG PET/CT scan in newly diagnosed diffuse large B cell lymphoma

To evaluate the prognostic value of maximum standard uptake (SUVmax) on pretreatment (18)F-fluoro-2-deoxyglucose ((18)F-FDG) positron emission tomography/computed tomography (PET/CT) scan in patients with newly diagnosed diffuse large B cell lymphoma (DLBCL). The clinical data of 39 DLBCL patients undergoing a PET/CT scan at pre-treatment from December 2009 to October 2011 were analyzed retrospectively. SUVmax on PET/CT was evaluated by SPSS 13.0 for the associations with patient characteristics, prognostic factors, treatment efficacy and survival time. The median SUVmax was higher in non-germinal center B cell-like (non-GCB) patients than that in GCB ones (18.0(2.2 - 40.5) vs 11.6 (5.3 - 18.7), P = 0.039). No difference of SUVmax was observed between the patients with and without bulky disease (P = 0.539). SUVmax was not associated with such patient characteristics as international protein index, age, stage, Eastern Cooperative Oncology Group performance status, lactate dehydrogenase, number of extranodal involvement and Ki-67 (all P > 0.05). No significant difference in median SUVmax existed between complete remission (CR) and non-CR patients (P = 0.312). The difference of SUVmax was insignificant for the patients with efficacy and no efficacy (P = 0.243). With the cut-off values of 10, 15, 20, the CR rate, response rate, 2-year progression-free survival (PFS) rate and 2-year overall survival (OS) rate were not different between the patients with SUVmax below and above cut-off value (all P > 0.05). The prognostic value of SUVmax on PET/CT is indeterminate. And it can not be used to predict the patient prognosis.

R-CHOP regimen can significantly decrease the risk of disease relapse and progression in patients with non-germinal center B-cell subtype diffuse large B-cell lymphoma.

To further explore the role of rituximab when added to the CHOP-like regimen in the treatment of immunohistochemically defined non-germinal center B-cell subtype (non-GCB) diffuse large B-cell lymphoma (DLBCL), 159 newly diagnosed DLBCL patients were studied retrospectively based on the immunohistochemical evaluation of CD10, Bcl-6, MUM-1, and Bcl-2. Altogether, 110 patients underwent the CHOP-like regimen, and rituximab was added for the other 49 patients. Cox regression analysis showed that compared with the CHOP-like regimen, the rituximab-based regimen (R-CHOP regimen) significantly decreased the risk of disease relapse and progression in CD10-negative patients (P = 0.001), Bcl-6-negative patients (P = 0.01), and MUM-1-positive patients (P = 0.003). The risk of disease relapse in patients with non-GCB subtype (P = 0.002) also decreased. In contrast, patients with the opposite immunohistochemical marker expression profile and GCB subtype did not benefit from treatment with the R-CHOP regimen. In addition, non-GCB subtype patients had a significantly higher expression rate of Bcl-2 than GCB subtype patients (P = 0.042). Although univariate analysis found that both Bcl-2-positive and -negative patients had significantly higher event-free survival rates with the R-CHOP regimen, only Bcl-2 positivity (P = 0.004) maintained significance in the Cox regression analysis. We conclude that the addition of rituximab can significantly improve the prognosis of patients with non-GCB subtype DLBCL, which is closely related to the expression of CD10, Bcl-6, MUM-1, and Bcl-2.

Prognostic impact of immunohistochemically defined germinal center B-cell and nongerminal center B-cell subtypes of diffuse large B-cell lymphoma in rituximab era.

e18517 Background: Diffuse large B-cell lymphoma (DLBCL) can be molecularly subtyped as either germinal center B-cell (GCB) or non-GCB. The role of rituximab(R) in these two groups remains unclear. Methods: We studied 204 patients with de novo DLBCL (107 treated with CHOP; 97 treated with R-CHOP); patients being stratified into GCB and non-GCB on the basis of BCL-6, CD10 and MUM1 protein expression. The relationships between clinical characteristics, survival data and immunophenotype were studied. Results: The median follow-up was 51months for CHOP group and 56 months for R-CHOP group. The 5-year overall survival (OS) in the CHOP and R-CHOP group was 50.4% and 66.6% (p=0.031), respectively. GCB patients had a better 5-year OS than non-GCB patients whether treated with CHOP (65.0% vs. 40.9%; p=0.011). In contrast, there’s no difference in the 5-year OS for the GCB and non-GCB with R-CHOP (76.5% vs. 61.3%; p=0.141). In non-GCB subtype, additional rituximab improved survival than CHOP (61.3% vs. 40.9%; p=0.0303). Conclusions: These results indicated that addition of rituximab to standard chemotherapy eliminate the prognostic value of immunohistochemically defined GCB and non-GCB phenotypes in DLBCL by improving the prognostic value of non-GCB subtype of DLBCL

High Ki‐67 expression in diffuse large B‐cell lymphoma patients with non‐germinal center subtype indicates limited survival benefit from R‐CHOP therapy

Rituximab has significantly improved the survival of patients with DLBCL, especially those with non-germinal center B-cell-like (non-GCB) subtype. The impact of Ki-67 expression, an index of proliferation, on the clinical outcomes of patients with DLBCL has largely been unexplored. This study aimed to investigate whether Ki-67 expression is an indicator of outcome in DLBCL patients (especially non-GCB DLBCL patients) treated with standard chemotherapy combined with rituximab. Expression of Ki-67 protein was examined immunohistochemically in 118 tumor specimens from patients newly diagnosed with DLBCL and treated with R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone). Overall survival (OS) and progression-free survival (PFS) were lower in patients with high Ki-67 expression than in those with low Ki-67 expression (3-year OS: 65.2% vs. 81.7%, P = 0.030; 3-year PFS: 56.4% vs. 73.3%, P = 0.020), similar in patients with GCB subtype and those with the non-GCB subtype (OS: P = 0.330; PFS: P = 0.287). According to Ki-67 expression status by immunophenotype subgroups, patients with high Ki-67 expression in non-GCB subgroup had the most unfavorable PFS and OS, comparing with the other three subgroups (P = 0.004 and P = 0.002, respectively). In multivariate analysis, non-GCB with high Ki-67 expression was an independent prognostic predictor of inferior survival in DLBCL patients treated with R-CHOP. For DLBCL patients with non-GCB DLBCL and high Ki-67 expression, the survival benefit from R-CHOP therapy is limited.

Bcl‐2 and BLIMP‐1 expression predict worse prognosis in gastric diffuse large B cell lymphoma (DLCBL) while other markers for nodal DLBCL are not useful

Previous studies have identified clinicopathological and immunohistochemical differences among diffuse large B cell lymphomas (DLBCL) as a function of disease location. Nevertheless, there is a continuing tendency to generalize the prognostic value of various identified markers without taking into account tumour site. Accordingly, we analysed the prognostic value of several of the immunohistochemical markers that have been proposed for nodal DLBCL in a group of patients with gastric DLBCL. Using histochemical methods, CD10, Bcl-6, Gcet1, MUM-1, Bcl-2 and BLIMP-1 expression was investigated in 43 cases of gastric DBLCL. As in nodal DLBCLs, expression of BLIMP-1, and of Bcl-2 in non-germinal centre B cell-like (non-GCB) patients, was associated with a worse prognosis. However, unlike nodal DBLCL, there was no significant association of prognosis with expression of CD10, Bcl-6, Gcet1 or MUM-1, or with categorization according to Hans or Muris algorithms. Although most markers of prognosis in nodal DLBCL are not useful indicators for gastric DLBCL, Bcl-2 or BLIMP-1 expression does correlate with worse prognosis. These data support the notion that clinicopathological features in DLBCL vary according to the disease location.

Outcome of R-CHOP or CHOP Regimen for Germinal Center and Nongerminal Center Subtypes of Diffuse Large B-Cell Lymphoma of Chinese Patients

Diffuse large B-cell lymphoma (DLBCL) can be molecularly subtyped as either germinal center B-cell (GCB) or non-GCB. The role of rituximab(R) in these two groups remains unclear. We studied 204 patients with de novo DLBCL (107 treated with first-line CHOP; 97 treated with first-line R-CHOP), patients being stratified into GCB and non-GCB on the basis of BCL-6, CD10, and MUM1 protein expression. The relationships between clinical characteristics, survival data, and immunophenotype (IHC) were studied. The 5-year overall survival (OS) in the CHOP and R-CHOP groups was 50.4% and 66.6% (P = 0.031), respectively. GCB patients had a better 5-year OS than non-GCB patients whether treated with CHOP or not (65.0% versus 40.9%; P = 0.011). In contrast, there is no difference in the 5-year OS for the GCB and non-GCB with R-CHOP (76.5% versus 61.3%; P = 0.141). In non-GCB subtype, additional rituximab improved survival better than CHOP (61.3% versus 40.9%; P = 0.0303). These results indicated that addition of rituximab to standard chemotherapy eliminates the prognostic value of IHC-defined GCB and non-GCB phenotypes in DLBCL by improving the prognostic value of non-GCB subtype of DLBCL.

Elevated Serum IL-10 Levels in Patients with Diffuse Large B Cell Lymphoma: A Mechanism of Aberrant JAK2 Kinase Activation

Abstract 960Diffuse large B cell lymphoma (DLBCL) is an aggressive lymphoma whose survival depends on various signaling pathways one of which is Signal transducer and activator of transcription 3 (STAT3)/Janus kinase 2 (JAK2). We have demonstrated that JAK2 is constitutively activated at the auto-phosphorylation site in many cases of DLBCL. The most common mechanism causing abnormal JAK2 activation is through dysregulated cytokine signaling. Cytokines are deregulated in several hematological malignancies and may play a role in tumor cell growth through receptor-mediated and ligand dependent activation of the JAK2 kinase. In this study we investigated the role of cytokine signaling in JAK2 activation in DLBCL and use of a novel JAK2 inhibitor (JAK2i) to inhibit IL-10 induced JAK/STAT signaling.We studied serum cytokines from 70 patients with new untreated DLBCL who participated in a clinical trial in the North Central Cancer Treatment Group (Micallef, IN et al Blood 2011). Compared to control sera, patients with DLBCL had higher levels of several JAK2 kinase related cytokines (IL-2, IL-6, IL-10, and EGF). IL-10 and IL-6 were significantly higher in DLBCL patients vs controls with p values >0.03 and >0.001, respectively. We next examined whether DLBCL cell lines produced IL-10. The phospho-JAK2 (pJAK2) positive DLBCL cell lines Ly10, DHL2 and HBL1 produced more IL-10 (40–80 pg/ml) than the pJAK2 negative cell lines Ly1, Ly19 and DHL6 (0–5 pg/ml). Analysis of the surface expression of IL-10 receptors (IL-10R) determined that most p-JAK2 positive DLBCL cells express either IL-10Ra or IL-10Rb or both. IL-10 had no effect on DLBCL cell survival in vitro; however, it did promote their proliferation. Only IL-10 (but not the other elevated cytokines) was specifically able to activate JAK2 and STAT3 phosphorylation in a subgroup of DLBCL cell lines. IL-10 was not able to activate JAK1, STAT1 and STAT5, which suggests a specific role of IL-10 in the JAK2 pathway. Moreover, neutralizing antibody to IL-10 inhibited IL-10-induced JAK2 and STAT3 tyrosine phosphorylation. We studied the effect of SAR302503 (SAR503, Sanofi, Cambridge, MA), a selective JAK2i currently in clinical trial for myelofibrosis on constitutive JAK2 signaling in DLBCL cells. SAR503 was able to inhibit JAK2 and STAT3 phosphorylation in a dose and time dependent manner in a variety of DLBCL cell lines and patient samples. JAK2 inhibition with SAR2503 caused a dose-dependent inhibitory effect on survival of pJAK2 positive DLBCL cells not observed in pJAK2 negative cells. Activation of STAT3 signaling up-regulates the expression of various genes involved in cell survival and proliferation such as bcl-xl, bcl-2, mcl-1 and c-myc. We observed a dose-dependent decrease in c-myc protein and mRNA levels in Ly3 and DHL2 cells with SAR503 treatment; however, SAR503 did not effect expression of bcl2, mcl-1 and bcl-xl proteins in DLBCL cells. Interestingly, JAK2 inhibition with SAR503 inhibited the autocrine secretion of IL-10 in a dose-dependent manner. Next, we determined if higher pre-treatment serum IL-10 correlates with the overall survival of 81 DLBCL patients. IL-10 by ELISA demonstrated that IL-10 levels were high in 51% (41/81) of patients (median, 57.7pg/ml; range, 26.1–503.7), and low in 49% (40/81) (median, 15.9 pg/ml; range, 0–25.9). Using a cut-off value of 26.1pg/ml, patients with a high serum IL-10 level had a significantly worse event-free survival (p=0.01). Clinical correlation of serum IL-10 with disease parameters showed that the IL-10 level was correlated with elevated serum LDH (p= 0.0085) and IPI score (p=0.01); there was no correlation with the number of extranodal sites, age, or B symptoms. DLBCL tumors from 40 patients were classified into germinal center B-cell type (GCB) and non-GCB type using the Hans algorithm. There was a clear trend towards a higher serum IL-10 in non-GCB DLBCL patients (p <0.06).In summary, our data identifies mechanisms of JAK2 kinase activation in DLBCL and supports the hypothesis that the IL-10-JAK2-cmyc pathway is activated in patients with DLBCL. Finally our data provide a mechanistic basis of selecting and targeting DLBCL tumor cells with high IL-10 levels and/or constitutive JAK2 activity with potent and novel JAK2 inhibitors such as SAR503. Disclosures:No relevant conflicts of interest to declare.

PYRAMID and LYM2034: Targeted randomized phase II studies of bortezomib with or without immunochemotherapy in newly diagnosed nongerminal center B-cell-like (GCB) diffuse large B-cell lymphoma (DLBCL), including rapid prospective non-GCB subtype identification.

TPS226 Background: The recognition of prognostically distinct subtypes of DLBCL by gene expression profiling has, until now, not led to improved outcomes. Conducting targeted studies in prospectively identified, molecularly distinct entities is challenging. PYRAMID and LYM2034 are prospectively identifying and enrolling non-GCB patients (pts). This subtype has inferior outcomes vs GCB following (R-)CHOP alone (Lenz, NEJM 2008; Fu, JCO 2008). The rationale for these studies is provided by data suggesting bortezomib shows benefit specifically in non-GCB DLBCL resulting from inhibition of the critical NF-κB survival pathway, which is activated in the non-GCB subtype. Bortezomib + dose-adjusted EPOCH showed superior response rates and survival in non-GCB vs GCB relapsed DLBCL (Dunleavy, Blood 2009), and in newly diagnosed DLBCL, bortezomib + R-CHOP showed similar outcomes in GCB and non-GCB pts (Ruan, JCO 2010). Methods: PYRAMID is enrolling pts at 55 centers in the US; LYM2034 is enrolling pts at 86 sites in Canada, Australia, and countries in Central and South America, Europe, and Asia. Pts aged ≥18 yrs with previously untreated non-GCB DLBCL (PYRAMID: all stages; LYM2034: stages II–IV), ECOG PS 0–2, and ≥1 measurable tumor mass are eligible. Non-GCB tumor subtyping for both studies is done at a single central laboratory via the Hans immunohistochemical assay (Hans, Blood 2004). Non-GCB pts are then randomized to receive six 3-week cycles of R-CHOP alone (rituximab 375 mg/m2, cyclophosphamide 750 mg/m2, doxorubicin 50 mg/m2, vincristine 1.4 mg/m2, all on day 1, plus prednisone 100 mg, days 1–5), or bortezomib 1.3 mg/m2 on days 1 and 4 plus R-CHOP (PYRAMID) or bortezomib 1.3 mg/m2 on days 1, 4, 8, and 11 plus R-CAP (R-CHOP minus vincristine; LYM2034). The primary endpoint is PFS at 2 yrs in PYRAMID and CR rate in LYM2034. To date in PYRAMID and LYM2034, respectively, 100 and 167 DLBCL pts have been screened, and 34 of the planned 190 and 62 of the planned 164 non-GCB pts have been randomized. PYRAMID (NCT00931918) and LYM2034 (NCT01040871) are registered with ClinicalTrials.gov.

Response of relapsed/refractory diffuse large B-cell lymphoma (DLBCL) with nongerminal center B-cell phenotype to lenalidomide (L) alone or in combination with rituximab (R).

8038 Background: Novel salvage therapies for relapsed/refractory (r/r) DLBCL and the identification of specific biomarkers predictive of response to a specific therapy are needed. L has an overall response rate (ORR) of 28% in r/r DLBCL. Methods: We retrospectively evaluated differences in clinical outcomes for germinal center B-cell (GCB)-like vs non-GCB-like DLBCL patients treated with salvage L alone (RPCI) or L+R (DHOS-S). We are augmenting the current database with pathology specimens from r/r DLBCL patients treated with L monotherapy at the Mayo Clinic and Hackensack Cancer Center. The initial data set from RPCI included 18 patients with r/r large cell lymphoma: 8M/10F; median age: 64 yrs; median 4 prior treatments. Patients were classified as GCB (n=9) or non-GCB (n=9) using the Hans criteria. Differences in overall response rate (ORR), CR or PR rates, progression-free survival (PFS), and overall survival (OS) were compared between GCB and non-GCB DLBCL. Results: No differences in stage, international prognostic index (IPI) score, prior number of treatments, were noted between the two groups. A significant difference in clinical response to L was observed: ORR was 77% for non-GCB patients vs 11% for GCB patients (P=0.011); and 44% of non- GCB patients achieved a CR vs 11% of patients with the GCB phenotype. PFS for patients with the non-GCB subtype was 336 days vs 72 days for patients with the GCB subtype (P=0.008). Although, median OS for the non-GCB subgroup was 420+ days compared with 73 days for GCB patients, it did not reach statistical significance (P=0.4). In a separate analysis, an additional 8 patients with r/r DLBCL (all non-GCB subtype), treated at the DHOS-S with L+R, achieved an ORR of 50%. This appears to be favorable relative to historical controls. Conclusions: Our data suggests that these two subgroups of patients with DLBCL (i.e. GCB vs non-GCB) appear to have a significantly different response to L in the r/r setting. Results from the analysis of the expanded data set are anticipated in time for the congress, and a large international trial is in development in an attempt to prospectively validate our findings. No significant financial relationships to disclose.

Classification of Newly Diagnosed Diffuse Large B-Cell Lymphoma (DLBCL) According to the Han's Criteria Defines Two Groups of Patients with Different Clinical Outcomes Following Systemic Rituximab-Multi Agent Anthracycline-Based Therapy.

Abstract 623Gene expression profiling has successfully distinguished three subtypes of DLBCL with different biology and response to treatment: 1) germinal center B-cell (GCB); and 2) non-germinal center lymphomas, that include: activated B-cell-like (ABC) and Type 3 subtypes. Currently, immunohistochemical (IHC) analysis of lymphoma biopsy specimens appear to be a more widely applicable methodology (i.e. compared to gene microarray analysis) to use in order to differentiate between subtypes of DLBCL. While the clinical benefit of adding rituximab to CHOP or CHOP-like chemotherapy as a front line treatment of DLBCL is beyond dispute, it also requires a re-evaluation of previously accepted biomarkers of response to CHOP or CHOP-like chemotherapy alone. The predictive value of “IHC–defined” GCB phenotype in rituximab-chemotherapy-treated patients continues to be controversial, as retrospective studies have reported conflicting results. In an attempt to define the predictive value of using the Han's algorithm in newly diagnosed DLBCL patients undergoing frontline immunochemotherapy, we retrospectively analyzed differences in progression free survival (PFS) and overall survival (OS) between patients with GCB and non-GCB DLBCL treated with equivalent doses of rituximab and anthracycline-based therapy at our institution. Using the tumor registry and the pharmacy database, we identified patients with DLBCL treated at our Institution between 2000 and 2008. Demographic, clinical, pharmacologic and pathological characteristics were obtained for each patient. Patients were classified into GCB or non-GCB DLBCL according to the Han's algorithm based on the expression of CD10, Bcl-6 and MUM-1 in the large cell component of the tumor specimen. Cumulative doses of rituximab (R), cyclophosphamide (C), doxorubicin (H), vincristine (O), etoposide (E,; when used) and prednisone (P) were calculated for each patient, as well as the number of cycles, dose delays, and growth factor use. A total of 192 patients were included in the study. The average age was 58.65 years (F/M:73/119). Using the Hans algorithm, n=55 (28.6%) and n=57 (29.7%) were classified as non-GCB or GCB, respectively. Inadequate information was availabel to classify 80 patients (undetermined group). Clinical indictors such as clinical demographics, international prognostic index (IPI) score, extra-nodal disease, performance status, Ann Arbor stage, therapy delays, cumulative rituximab and chemotherapy doses were not significantly different between groups (non-GCB, GCB, and undetermined DLBCL). The majority of patients received R+CHOP (90%) or R+ dose adjusted–EPOCH. On follow-up, a total of 42 (21.8%) patients relapsed or were found to have primary-refractory disease. The complete remission rate to front-line therapy was 81% for the entire cohort of patients and was not different between patients with GCB or non-GCB DLBCL. On the other hand, significant differences in PFS and OS were observed between patients with non-GCB versus GCB DLBCL. The 5-year progression free survival (PFS) and overall survival (OS) were significantly better in the GCB DLBCL subtype (75.4% vs. 56.4%, p=0.017 and 84.2% vs. 70.9 %, p=0.037; respectively). As no differences in clinical parameters, CR rate, or rituximab-chemotherapy dose/schedule were observed between non-GCB and GCB DLBCL patients, it is possible that intrinsic biological pathways involved in lymphomagenesis and/or “resistance” of these subtypes of DLBCL may play a role in their responsiveness to rituximab-based immunochemoimmunotherapy. In summary, our data suggest that the Hans algorithm can predict the clinical outcome of patients with DLBCL undergoing front-line therapy with R-chemotherapy. Patients with non-GCB DLBCL while having a comparable initial complete response rate to R+CHOP had a shorter PFS and OS than GCB DLBCL patients. Non-GCB DLBCL represents a subgroup of DLBCL for which innovative therapeutic strategies targeting key regulatory pathways in the induction and/or maintenance setting are needed in an attempt to prolong PFS and improve OS. Disclosures:No relevant conflicts of interest to declare.

Rituximab plus CHOP (R-CHOP) overcomes PRDM1-associated resistance to chemotherapy in patients with diffuse large B-cell lymphoma

The positive regulatory domain I (PRDM1) is a master regulator in the differentiation of mature B lymphocytes to plasma cells. It has 2 isoforms, PRDM1alpha and PRDM1beta, and is regulated by the transcriptional regulator nuclear factor kappa (NF)-kappaB. PRDM1 protein expression was recently demonstrated in a subset of diffuse large B-cell lymphoma (DLBCL) with aggressive behavior, a type of lymphoma for which rituximab associated with chemotherapy (R-CHOP) is now widely indicated. Using laser microdissection combined with reverse transcription-polymerase chain reaction (RT-PCR) amplification, PRDM1 gene expression was assessed in 82 DLBCL patients. The results showed that both PRDM1alpha and PRDM1beta transcripts were expressed in microdissected lymphoma cells only in the non-germinal center B-cell-like (non-GCB) subtype of DLBCL. PRDM1beta gene expression was correlated with short survival time in the non-GCB patients treated with CHOP but not with R-CHOP. In vitro, B-lymphoma cells resistant to chemotherapy expressed PRDM1beta. Rituximab suppressed PRDM1beta expression, which was concomitant with NF-kappaB inactivation. The value of PRDM1beta expression as a prognostic marker in non-GCB DLBCL might thus be considered. This study confirms the efficiency of rituximab on DLBCL and allows a better understanding of one of its biologic actions.