Prognostic Markers and Mechanisms of Chemotherapy Resistance in Diffuse Large B-cell Lymphoma

Diffuse large B-cell lymphoma (DLBCL) is an aggressive and heterogeneous disease. Identification of prognostic and predictive markers is important to design individualised and effective treatment strategies. This thesis describes different approaches to search for molecular prognostic markers and an attempt to overcome chemotherapy resistance in DLBCL. In the first study it was investigated whether immunohistochemical expression of CD40, previously associated with a favourable prognosis in DLBCL, had any prognostic impact after the addition of rituximab to anthracycline-based chemotherapy. Results showed better prognosis in CD40-positive patients receiving this combined treatment. An inflammatory stromal process was observed in CD40-expressing tumours when using gene expression profiling, possibly contributing to a better prognosis in CD40-positive patients. A study about the effect of inhibited protein prenylation on the response to CHOP therapy, using an in vitro cell-line-based model, showed that treatment with geranylgeranylation inhibitors in DLBCL cell lines had a chemo-sensitising effect. This indicates that inhibition of geranylgeranylation may prove a useful strategy for overcoming CHOP resistance in DLBCL. A recombinant antibody microarray was used to search for prognostic protein profiles in plasma from DLBCL patients in an attempt to identify new candidate markers for the prognosis and treatment response in DLBCL and to provide a basis for future investigations and validation. The results of this work indicated that the tumour microenvironment and host immune response contribute to the prognosis in DLBCL, and suggest a potential novel strategy to overcome chemotherapy resistance. Further molecular profiling is important for improved treatment of patients with DLBCL

The histone deacetylase inhibitor valproic acid sensitizes diffuse large B-cell lymphoma cell lines to CHOP-induced cell death.

Epigenetic code modifications by histone deacetylase inhibitors (HDACis) have recently been proposed as potential new therapies for hematological malignancies. Diffuse large B-cell lymphoma (DLBCL) is the most common form of aggressive lymphoma. At present, standard first line treatment for DLBCL patients is the antracycline-based chemotherapy regimen CHOP (cyclophosphamide, doxorubicin, vincristine and prednisone) combined with the monoclonal anti-CD20 antibody rituximab (R-CHOP). Since only 50-60% of patients reach a long-time cure by this treatment, there is an urgent need for novel treatment strategies to increase the response and long-term remission to initial R-CHOP therapy. In this study, we investigated the effect of the HDAC inhibitor valproic acid (VPA) on DLBCL cell lines. To elucidate the effects of VPA on chemo-sensitivity, we used a cell-line based model of CHOP-refractory DLBCL. All five DLBCL cell lines treated with VPA alone or in combination with CHOP showed decreased viability and proliferation. The VPA-induced sensitization of DLBCL cells to cytotoxic treatment resulted in increased number of apoptotic cell as judged by annexin V-positivity and the presence of cleaved caspase-3. In addition, pretreatment with VPA resulted in a significantly increased DNA-damage as compared to CHOP alone. In summary, HDAC inhibitors such as VPA, are promising therapeutic agents in combination with R-CHOP for patients with DLBCL

CD40 is a potential marker of favorable prognosis in patients with diffuse large B-cell lymphoma treated with immunochemotherapy.

We have previously shown that expression of CD40 has a favorable prognostic impact in diffuse large B-cell lymphoma (DLBCL) after anthracycline-based chemotherapy. Here we examined the prognostic value of immunohistochemically defined CD40 expression in 95 patients with DLBCL treated with both anthracycline-based chemotherapy and rituximab. Using a 10% cut-off level, 77% of the patients had CD40-positive tumors and showed a superior overall survival (p = 0.02 log-rank, hazard ratio 0.35, 95% CI 0.14-0.88, p = 0.03 Cox regression). When adjusted for International Prognostic Index in multivariate analysis, CD40 was not an independent prognostic factor (hazard ratio 0.39, 95% CI 0.15-1.04, p = 0.06 Cox regression). However, even after the introduction of immunochemotherapy, CD40 has a potential prognostic impact in DLBCL. Additional and larger studies are necessary, regarding the immunohistochemical robustness of CD40 and the biological mechanisms that contribute to the superior prognosis in CD40-expressing DLBCL

Prognostic impact of protein kinase C beta II expression in R-CHOP-treated diffuse large B-cell lymphoma patients

Development of targeted agents for the treatment of diffuse large B-cell lymphoma includes clinical evaluation of enzastaurin, an agent that suppresses signaling through protein kinase C-beta and AKT pathways. To determine whether protein kinase C-beta expression has prognostic significance for diffuse large B-cell lymphoma patients treated with immunochemotherapy, we analyzed the expression of protein kinase C-beta II, BCL-2 and cell of origin immunohistochemically from pretreatment samples of 95 diffuse large B-cell lymphoma patients. All patients received rituximab with CHOP or CHOEP. According to Kaplan-Meier analyses, overall survival at 3 years was better among the patients with low than high protein kinase C-beta II protein levels (94 vs 76%, P = 0.036). The prognostic value of protein kinase C-beta II expression on survival was seen in the patients with low and high International Prognostic Index risk groups, and in all molecular entities. Gene expression data from an independent set of 233 diffuse large B-cell lymphoma patients treated with a combination of rituximab and CHOP-like chemotherapy was analyzed in comparison. Accordingly, a better 3-year overall survival was observed among the subgroup with low protein kinase C-beta II mRNA levels (84 vs 68%, P = 0.005). In multivariate analysis with cell of origin, protein kinase C-beta II mRNA expression remained as an independent predictor for overall survival. Together, the data show that protein kinase C-beta II expression has prognostic significance in diffuse large B-cell lymphoma patients treated with immunochemotherapy. Modern Pathology (2010) 23, 686-693; doi: 10.1038/modpathol.2010.43; published online 26 February 201

Inhibition of geranylgeranylation mediates sensitivity to CHOP-induced cell death of DLBCL cell lines.

Prenylation is a post-translational hydrophobic modification of proteins, important for their membrane localization and biological function. The use of inhibitors of prenylation has proven to be a useful tool in the activation of apoptotic pathways in tumor cell lines. Rab geranylgeranyl transferase (Rab GGT) is responsible for the prenylation of the Rab family. Overexpression of Rab GGTbeta has been identified in CHOP refractory diffuse large B cell lymphoma (DLBCL). Using a cell line- based model for CHOP resistant DLBCL, we show that treatment with simvastatin, which inhibits protein farnesylation and geranylgeranylation, sensitises DLBCL cells to cytotoxic treatment. Treatment with the farnesyl transferase inhibitor, FTI-277, or the geranylgeranyl transferase I inhibitor, GGTI-298, indicates that the reduction in cell viability was restricted to inhibition of geranylgeranylation. In addition, treatment with BMS1, a combined inhibitor of farnesyl transferase and Rab GGT, resulted in a high cytostatic effect in WSU-NHL cells, demonstrated by reduced cell viability and decreased proliferation. Co-treatment of BMS1 or GGTI-298 with CHOP showed synergistic effects with regard to markers of apoptosis. We propose that inhibition of protein geranylgeranylation together with conventional cytostatic therapy is a potential novel strategy for treating patients with CHOP refractory DLBCL

Gene expression profiling indicates that immunohistochemical expression of CD40 is a marker of an inflammatory reaction in the tumor stroma of diffuse large B-cell lymphoma

Immunohistochemical expression of CD40 is seen in 60-70% of diffuse large B-cell lymphoma (DLBCL) and is associated with a superior prognosis. By using gene expression profiling we aimed to further explore the underlying mechanisms for this effect. Ninety-eight immunohistochemically defined CD40 positive or negative DLBCL tumors, 63 and 35 respectively, were examined using spotted 55K oligonucleotide arrays. CD40 expressing tumors were characterized by up-regulated expression of genes encoding proteins involved in cell-matrix interactions: collagens, integrin a V, proteoglycans and proteolytic enzymes, and antigen presentation. Immunohistochemistry confirmed that CD40 positive tumors co-express the proinflammatory proteoglycan biglycan (p = 0.005), which in turn correlates with the amount of infiltrating macrophages and CD4 and CD8 positive T-cells. We postulate that immunohistochemical expression of CD40 mainly reflects the inflammatory status in tumors. A high intratumoral inflammatory reaction may correlate with an increased autologous tumor response, and thereby a better prognosis

The dual role of CD70 in B‐cell lymphomagenesis

Background CD70 is a costimulatory molecule that is transiently expressed on a small set of activated lymphocytes and is involved in T-cell-mediated immunity. However, the role of CD70 in B-cell malignancies remains controversial. Methods We investigated the clinical relevance of CD70 genetic alterations and its protein expression in two diffuse large B-cell lymphoma (DLBCL) cohorts with different ethnic backgrounds. We also performed transcriptomic analysis to explore the role of CD70 alterations in tumour microenvironment. We further tested the blockade of CD70 in combination with PD-L1 inhibitor in a murine lymphoma model. Results We showed that CD70 genetic aberrations occurred more frequently in the Chinese DLBCL cohort (56/233, 24.0%) than in the Swedish cohort (9/84, 10.8%), especially in those with concomitant hepatitis B virus (HBV) infection. The CD70 genetic changes in DLBCL resulted in a reduction/loss of protein expression and/or CD27 binding, which might impair T cell priming and were independently associated with poor overall survival. Paradoxically, we observed that over-expression of CD70 protein was also associated with a poor treatment response, as well as an advanced disease stage and EBV infection. More exhausted CD8+ T cells were furthermore identified in CD70 high-expression DLBCLs. Finally, in a murine lymphoma model, we demonstrated that blocking the CD70/CD27 and/or PD1/PD-L1 interactions could reduce CD70+ lymphoma growth in vivo, by directly impairing the tumour cell proliferation and rescuing the exhausted T cells. Conclusions Our findings suggest that CD70 can play a role in either tumour suppression or oncogenesis in DLBCL, likely via distinct immune evasion mechanisms, that is, impairing T cell priming or inducing T cell exhaustion. Characterisation of specific dysfunction of CD70 in DLBCL may thus provide opportunities for the development of novel targeted immuno-therapeutic strategies

COMMD1 protein expression and outcome.

<p>Representative examples of low (A) and high (B) expression levels of COMMD1 in FFPE DLBCL tissue (original magnifications 100×, and 400×). C–D. Outcome according to COMMD1 expression in the trial specific TMA cohort. PFS in in the whole TMA cohort (C) and in the GCB subgroup (D). E–F. Outcome according COMMD1 expression in the validation cohort. PFS in in the whole validation cohort (E) and in the GCB subgroup (F). The cutoff point (staining coverage of 8.9%) for survival outcomes (COMMD1 low vs high) was selected by the ROC curve analysis in the training set, and then applied also to validation cohort.</p

Survival of DLBCL patients according to genomic aberrations.

<p>PFS (A and C) and lymphoma-associated OS (B and D) rates according to indicated genomic aberration.</p