ALBERT

Description: We used biopsy specimens of primary nodal diffuse large B-cell lymphoma (DLBCL) to investigate whether the inhibition of caspase 8 and/or 9 apoptosis signaling pathways predicts clinical outcome. Expression levels of cellular FLICE inhibitory protein (c-Flip) and numbers of active caspase 3-positive lymphoma cells were used to determine the status of the caspase 8-mediated pathway. Expression levels of Bcl-2 and X-linked inhibitor of apoptosis (XIAP) were used to determine the status of the caspase 9-mediated pathway. Expression of c-Flip, XIAP, Bcl-2, and caspase 3 activity all provided prognostic information. According to these immunohistochemical parameters, inhibition of either or both caspase signaling pathways was detected in all patients. Three groups of patients were identified, one with a caspase 8 inhibition profile, one with caspase 8 and 9 inhibition profiles, and one with a caspase 9 inhibition profile. Caspase 9 inhibition was strongly associated with poor response to chemotherapy and usually with fatal outcome, whereas caspase 8 inhibition was associated with excellent clinical outcome. Thus, our data strongly suggest that inhibition of the caspase 9-mediated pathway, but not the caspase 8-mediated pathway, is a major cause for therapy resistance in patients with nodal DLBCL.

Description: Abstract 3092 Enteropathy-associated T-cell lymphoma (EATL) is a rare intestinal lymphoma that arises from intraepithelial lymphocytes. In Western countries EATL accounts for 5% of all gastrointestinal lymphomas and in 80–90% of all cases this lymphoma is associated with celiac disease (CD). Based on clinical presentation, EATL can be divided into two subtypes: primary and secondary EATL. Primary EATL develops without a preceding history of CD. The first presentation is often perforation or obstruction, which leads to diagnosis of both EATL and CD. Secondary EATL is diagnosed in patients with well-established CD or refractory CD. These patients deteriorate and eventually develop EATL. The current standard treatment for both types of EATL consists of surgery and chemotherapy, but overall survival (OS) is poor and new therapeutic strategies are urgently needed. For risk-based selection of patients for new therapies and clinical trials, prognostic models as the International Prognostic Index (IPI) are generally used. Since IPI is not predictive for EATL, we determined a prognostic model specifically for EATL, which can identify high-risk patients who need more aggressive therapy. Forty-one patients were diagnosed with EATL and retrospectively analyzed. Two- and 5-years OS were 18% and 10% respectively (range: 0 – 97 months). In multivariate analysis, 3 risk factors were predictive for survival: serum LDH 〉 normal (P 〈 0.001; RR 6.65; 95% CI 1.96 to 9.89), presence of B-symptoms (P 〈 0.001; RR 4.41; 95% CI 2.73 to 16.18) and subtype secondary EATL (P = 0.036; RR 2.33; 95% CI 1.06 to 5.13). A weighted point score was assigned to each of these 3 factors and a prognostic model was constructed. Four risk groups were identified (P 〈 0.0001). Group I showed most favorable outcome: 2- and 5-years OS were 55% and 30% respectively. Although survival rates in groups II, III and IV were significantly different, in none of these groups 2-years survival was achieved. Therefore, the model was simplified to a low risk and a high risk group (P 〈 0.0001, Figure 1). The low risk group represented patients with no risk factors, i.e. primary EATL with no B-symptoms and normal LDH. In the high risk group, patients had 1 or more of the risk factors elevated serum LDH, B-symptoms or subtype secondary EATL. The new prognostic model showed superior predictive capacity as compared to IPI. In conclusion, our new prognostic model clearly identifies a high and a low risk group. Patients with one or more of the risk factors serum LDH 〉 normal, B-symptoms or subtype secondary EATL are at high risk, and therefore new therapies for this group are urgently needed. Figure 1: Survival in EATL. Low risk group = no risk factors. High risk group = presence of 1 or more of the following risk factors: serum LDH 〉 normal, B-symptoms or subtype secondary EATL. Figure 1:. Survival in EATL. Low risk group = no risk factors. High risk group = presence of 1 or more of the following risk factors: serum LDH 〉 normal, B-symptoms or subtype secondary EATL. Disclosures: No relevant conflicts of interest to declare.

Description: Disruption of the apoptosis signaling cascade is a probable cause for resistance to chemotherapy in patients with diffuse large B-cell lymphomas (DLBCL). We investigated whether inhibition of either or both caspase 8 and 9 apoptosis signaling pathways in biopsy specimens of primary nodal (DLBCL) predicts clinical outcome. Expression levels of c-Flip and numbers of active caspase 3 positive lymphoma cells were used to determine the status of the caspase 8 mediated pathway. Expression levels of Bcl-2 and XIAP were used to determine the status of the caspase 9 mediated pathway. Expression of c-FLIP, XIAP and Bcl-2 and caspase 3 activity all provided prognostic information. According to these immuno-histochemical parameters, inhibition of either or both caspase signaling pathways was detected in all cases. Three groups were identified: one with a caspase 8 inhibition profile, one with a caspase 8 and 9 inhibition profile and one with a caspase 9 inhibition profile. The caspase 9 inhibition profile was strongly associated with a poor response to chemotherapy and a usually fatal outcome, whereas the caspase 8 inhibition profile was associated with excellent clinical outcome. Functional analysis of apoptosis sensitivity confirmed that apoptosis profile was directly related to chemotherapy sensitivity. Thus, our data strongly suggest that inhibition of the caspase 9 and not the caspase 8 mediated pathway is a major cause for therapy resistance in patients with nodal DLBCL.

Description: The combination of chimeric CD20 monoclonal antibody (mAb) rituximab (R) with chemotherapy (CHOP) has significantly improved clinical outcome in patients with diffuse large B-cell lymphoma (DLBCL). However, the efficacy of R-CHOP is variable and DLBCL remains fatal in 30–40% of the patients. We recently developed the novel fully human CD20 mAb, ofatumumab (2F2) that is currently in clinical development for CLL and follicular lymphoma (phase III) and rheumatoid arthritis (phase II). In this study, we compared ofatumumab with rituximab for their ability to induce complement dependent cytotoxicity (CDC) of isolated lymphoma cells of chemotherapy-refractory DLBCL patients. Human type II CD20 mAb 11B8 does not induce CDC and was used as a control. Ofatumumab and rituximab induced CDC of all DLBCL samples tested, including the DLBCL cell lines SUDHL4, SUDHL5 and HT and lymphoma cells derived from ten chemotherapy-refractory DLBCL patients. Ofatumumab was significantly more effective in inducing CDC in nine out of ten DLBCL tumor samples when compared to rituximab (p=0.001, Two-way-Anova). The lethal doses (LD50) for ofatumumab (0.1 ± 2.8 μg/ml) was significantly lower when compared to the LD50 for rituximab (6.4 ± 4.9 μg/ml, p=0.04, Mann-Whitney test). The control CD20 mAb 11B8 showed no CDC induction of DLBCL cells. Sensitivity of DLBCL patient cells to ofatumumab- and rituximab-induced CDC negatively correlated with expression of complement defense molecule CD59, but not with expression of CD46, CD55, as determined by immunohistochemistry or apoptosis inhibitors Bcl-2 and XIAP. Functional inhibition of CD55 and CD59 using blocking mAb demonstrated that ofatumumab-induced CDC of DLBCL tumor cells was less sensitive to expression of these complement defense molecules than rituximab-induced CDC. We conclude that chemotherapy-refractory DLBCL cases are sensitive to CD20 mAb induced CDC with ofatumumab being the most effective mAb, especially in patients expressing high levels of CD59. Based on our results ofatumumab should be considered as a valuable therapy option for chemotherapy-refractory DLBCL patients.

Description: Systemic (nodal) anaplastic large cell lymphoma (ALCL) is a subgroup of T-cell non-Hodgkin’s lymphomas with a relatively favorable clinical outcome. Part of systemic ALCLs harbor a genetic aberration (usually the t(2;5)(p23;q35) translocation) containing the anaplastic lymphoma kinase (ALK) gene at 2p23, which results in aberrant expression of the ALK protein. Recently, we have shown that the presence of high percentages of activated cytotoxic T lymphocytes (CTLs) in tumor biopsy specimens of Hodgkin’s disease (HD) is associated with a poor prognosis. In the present study, we investigated the prognostic value of percentages of activated CTLs in combination with ALK expression in primary nodal ALCL. Primary nodal biopsies of 42 patients with ALCL were investigated for the percentage of activated CTLs (quantified using Q-PRODIT) and the expression of ALK by immunohistochemistry using monoclonal antibodies (MoAbs) directed against T-cell antigen granzyme B (GrB) and ALK, respectively. These parameters were evaluated for their predictive value regarding progression-free and overall survival time. The presence of a high percentage of activated CTLs (ie, ≥15%) was found to be an unfavorable prognostic marker. In combination with a lack of ALK expression, it was possible to identify a group of patients with a very poor prognosis. In this group, 13 of 16 patients died within 2 years as a result of the disease. Of the remaining 26 patients, only three (all ALK negative) died (P 〈 .0001). Furthermore, the percentage of activated CTLs combined with ALK status appeared to be of stronger prognostic value than the International Prognostic Index (IPI). We conclude that a high percentage of activated CTLs present in biopsy material of patients with primary nodal ALCL is a strong indicator for an unfavorable clinical outcome. The combination of ALK expression and percentage of activated CTLs appears to be more sensitive than the IPI in identifying a group of patients with a highly unfavorable clinical outcome who may be eligible for alternative (high dose) therapy schemes.

Description: Clinical outcome in patients with diffuse large B-cell lymphomas (DLBCL) is correlated with expression of inhibitors of the intrinsic apoptosis pathway, including XIAP. XIAP suppresses apoptosis through inhibiting active caspases-3, -7 and -9. In this study we investigated if the small-molecule XIAP antagonist 1396–12 induces cell death in cultured lymphoma cells of DLBCL patients and whether it is possible to predict whether a DLBCL will be sensitive to the XIAP antagonist. Treatment with this XIAP antagonist resulted in induction of apoptosis in 16 of 20 tested DLBCL samples. Sensitivity to the XIAP antagonist was observed in both chemotherapy refractory and responsive DLBCL, but did not affect peripheral blood mononuclear cells and tonsil germinal center B-cells from healthy donors. XIAP antagonist-sensitive cases were characterized by high expression levels of XIAP and relatively low expression levels of Bcl-2. In addition, we found that XIAP antagonist sensitive lymphomas are characterized by constitutive caspase-9 activation and that the apoptosis inducing effect of the XIAP antagonist depends on this constitutive caspase 9 activity. These data indicate that the small-molecule XIAP antagonist can induce apoptosis in DLBCL cells by restoring caspase 9 mediated apoptosis and therefore should be considered for possible development as a therapy for these patients. In vitro sensitivity to the XIAP antagonist can be predicted based on biological markers suggesting the possibility of pre-defining patients most likely to benefit from XIAP antagonist therapy.

Description: Abstract 2847 Anaplastic large cell lymphoma (ALCL) is a CD30 positive T-cell lymphoma that can be divided into a systemic and a primary cutaneous type. Systemic ALCL can be further divided into an anaplastic lymphoma kinase (ALK) expressing type and an ALK-negative type. Despite intensive treatment regimens, the disease will be fatal in 20–30% of the systemic ALK-positive and 50–70% of the systemic ALK-negative ALCL patients. A recent study in primary ALCL samples has demonstrated an increased expression of a fraction of NF-κB target genes, suggesting upregulation of NF-κB activity in ALCL tumor cells. NF-κB activity can be inhibited by the proteasome inhibitor bortezomib resulting in induction of apoptosis. In this study, we therefore investigated if bortezomib can induce apoptosis of cultured lymphoma cells of three systemic ALK-positive and three ALK-negative ALCL patients and seven ALCL cell lines and we examined the mechanisms by which bortezomib induced cytotoxicity in these ALCL cells. Treatment with bortezomib resulted in induction of apoptosis in all ALK-positive and ALK-negative ALCL patient samples and ALCL cell lines tested, when we compared the percentage cell death with the non-neoplastic CD4- and CD8-positive PBMC and tonsil T-cells from healthy donors. The lethal dose (LD50) varied between 54nM and more than 100nM after 24 hours and varied between 21nM and 52nM after 48 hours of exposure. ALK-negative ALCL cases were more sensitive to bortezomib and showed significant lower LD50 values than ALK-positive ALCL cells. We show that bortezomib-induced cell death in ALK-positive and ALK-negative ALCL is dependent on caspase-9 and/or caspase-8 mediated apoptosis and that bortezomib induces depolarization of the mitochondrial membrane. mRNA-expression and protein analysis revealed clearly upregulation of the BH3-only proteins Noxa, Bik and Puma, resulting in Bak and Bax release from the anti-apoptotic proteins Mcl-1 and Bcl-2. We also demonstrated that ALCL cells relatively resistant to bortezomib were characterized by high expression of Bcl-2A1, suggesting the possibility of pre-defining patients most likely to benefit from bortezomib therapy. Our preclinical data support the therapeutic application of bortezomib as potential drug in the treatment of ALCL, especially ALK-negative ALCL patients to improve their prognosis. Disclosures: No relevant conflicts of interest to declare.

Description: In vitro studies suggest that resistance to chemotherapy-induced apoptosis might explain poor response to therapy in fatal cases. Actual execution of apoptosis depends on proper functioning of effector caspases, particularly caspase 3, and on the expression levels of apoptosis-regulating proteins, including Bcl-2 and the recently identified granzyme B– specific protease inhibitor 9 (PI9). Thus, high levels of caspase 3 activation should reflect proper functioning of the apoptosis pathways, resulting in chemotherapy-sensitive neoplastic cells and a favorable prognosis. We tested this hypothesis by quantifying numbers of tumor cells positive for active caspase 3, Bcl-2, and PI9, respectively, in pretreatment biopsies of systemic anaplastic large cell lymphoma (ALCL) patients and by comparing these numbers with clinical outcome. Activation of caspase 3 in more than 5% of the tumor cells was strongly correlated with a highly favorable outcome. High numbers of Bcl-2– and PI9-positive tumor cells were found to predict unfavorable prognosis. This prognostic effect was strongly related to anaplastic lymphoma kinase (ALK) status: ALK-positive ALCL had significantly higher levels of active caspase 3, while high expression of the antiapoptotic proteins Bcl-2 and PI9 was almost completely restricted to ALK-negative cases. In conclusion, high numbers of active caspase 3–positive tumor cells predict a highly favorable prognosis in systemic ALCL patients. Poor prognosis is strongly related to high numbers of Bcl-2– and PI9-positive neoplastic cells. These data support the notion that a favorable response to chemotherapy depends on an intact apoptosis cascade. Moreover, these data indicate that differences in prognosis between ALK-positive and ALK-negative ALCL might be explained by differences in expression of apoptosis-inhibiting proteins.

Description: Clinical outcome in patients with primary nodal diffuse large B-cell lymphomas (DLBCLs) is correlated with expression of inhibitors of the intrinsic apoptosis pathway, including X-linked inhibitor of apoptosis protein (XIAP). XIAP suppresses apoptosis through inhibiting active caspase-3, caspase-7, and caspase-9. In this study, we investigated to see if the small-molecule XIAP antagonist 1396-12 induces cell death in cultured lymphoma cells of patients with DLBCL. Treatment with this XIAP antagonist resulted in relief of caspase-3 inhibition and in induction of apoptosis in 16 of 20 tested DLBCL samples. Sensitivity to the XIAP antagonist was observed in both chemotherapy-refractory and -responsive DLBCL, but did not affect peripheral blood mononuclear cells and tonsil germinal-center B cells from healthy donors. XIAP antagonist-sensitive samples were characterized by high expression levels of XIAP, relatively low expression levels of Bcl-2, and by constitutive caspase-9 activation. These data indicate that the small-molecule XIAP antagonist can induce apoptosis in cultured DLBCL cells and therefore should be considered for possible development as a therapy for these patients. In vitro sensitivity to the XIAP antagonist can be predicted based on biological markers, suggesting the possibility of predefining patients most likely to benefit from XIAP antagonist therapy.