Constitutive nuclear factor-kappaB-RelA activation is required for proliferation and survival of Hodgkin's disease tumor cells

The pathogenesis and etiology of Hodgkin's disease, a common human malignant lymphoma, is still unresolved. As a unique characteristic, we have identified constitutive activation of the transcription factor nuclear factor (NF)-kappaB p50-RelA in Hodgkin/Reed-Sternberg (H/RS) cells, which discriminates these neoplastic cells from most cell types studied to date. In contrast to other lymphoid and nonlymphoid cell lines tested, proliferation of H/RS cells depended on activated NF-kappaB. Furthermore, constitutive NF-kappaB p50-RelA prevented Hodgkin's lymphoma cells from undergoing apoptosis under stress conditions. Consistent with this dual function, Hodgkin's lymphoma cells depleted of constitutive nuclear NF-kappaB revealed strongly impaired tumor growth in severe combined immunodeficient mice. Our findings identify NF-kappaB as an important component for understanding the pathogenesis of Hodgkin's disease and for developing new therapeutic strategies against it.

Nuclear localization and increased levels of transcription factor YB-1 in primary human breast cancers are associated with intrinsic MDR1 gene expression

Breast cancers are either primarily resistant to chemotherapy (intrinsic resistance), or respond to chemotherapy but later recur with a multidrug-resistant phenotype because of overexpression of the multidrug transporter P-glycoprotein. The MDR1 gene encoding P-glycoprotein may be transcriptionally regulated by a Y-box transcription factor. We now report that, in multidrug-resistant MCF-7 breast cancer cells, nuclear localization of YB-1 is associated with MDR-1 gene expression. In drug-sensitive MCF-7 cells, however, YB-1 was localized to the cytoplasm. Regulated overexpression of YB-1 in drug-sensitive diploid breast epithelial cells induced MDR-1 gene expression and multidrug resistance. In 27 out of 27 untreated primary breast cancers, YB-1 protein was expressed in the cytoplasm although it was undetectable in normal breast tissue of these patients. In a subgroup of tumors (9/27), however, YB-1 was also localized to the nucleus and, in these cases, high levels of P-glycoprotein were present. These results show that in a subset of untreated primary breast cancers, nuclear localization of YB-1 protein is associated with intrinsic multidrug resistance. Our data show that YB-1 has an important role in controlling MDR1 gene transcription and this finding provides a basis for the analysis of molecular mechanisms responsible for intrinsic multidrug resistance in human breast cancer.

Molecular mechanisms of constitutive NF-kappaB/Rel activation in Hodgkin/Reed-Sternberg cells

A common characteristic of malignant cells derived from patients with Hodgkin's disease (HD) is a high level of constitutive nuclear NF-kappaB/Rel activity, which stimulates proliferation and confers resistance to apoptosis. We have analysed the mechanisms that account for NF-kappaB activation in a panel of Hodgkin/Reed-Sternberg (H-RS) cell lines. Whereas two cell lines (L428 and KMH-2) expressed inactive IkappaBalpha, no significant changes in NF-kappaB or IkappaB expression were seen in other H-RS cells (L591, L1236 and HDLM-2). Constitutive NF-kappaB was susceptible to inhibition by recombinant IkappaBalpha, suggesting that neither mutations in the NF-kappaB genes nor posttranslational modifications of NF-kappaB were involved. Endogenous IkappaBalpha was bound to p65 and displayed a very short half-life. IkappaBalpha degradation could be blocked by inhibitors of the NF-kappaB activating pathway. Proteasomal inhibition caused an accumulation of phosphorylated IkappaBalpha and a reduction of NF-kappaB activity in HDLM-2 and L1236 cells. By in vitro kinase assays we demonstrate constitutive IkappaB kinase (IKK) activity in H-RS cells, indicating ongoing signal transduction. Furthermore, H-RS cells secrete one or more factor(s) that were able to trigger NF-kappaB activation. We conclude that aberrant activation of IKK's, and in some cases defective IkappaBs, lead to constitutive nuclear NF-kappaB activity, which in turn results in a growth advantage of Hodgkin's disease tumor cells.

Activation of caspase-8 in drug-induced apoptosis of B-lymphoid cells is independent of CD95/Fas receptor-ligand interaction and occurs downstream of caspase-3

The activation of caspase-8, a crucial upstream mediator of death receptor signaling, was investigated in epirubicin- and Taxol-induced apoptosis of B-lymphoma cells. This study was performed because the CD95/Fas receptor-ligand interaction, recruitment of the Fas-associated death domain (FADD) adaptor protein, and subsequent activation of procaspase-8 have been implicated in the execution of drug-induced apoptosis in other cell types. Indeed, active caspase-8 was readily detected after treatment of mature and immature B-lymphoid cells with epirubicin or Taxol. However, neither constitutive nor drug-induced expression of the CD95/Fas ligand was detectable in B-lymphoma cells. Furthermore, overexpression of a dominant-negative FADD mutant (FADDdn) did not block caspase-8 processing and subsequent DNA fragmentation, indicating that drug-induced caspase-8 activation was mediated by a CD95/Fas-independent mechanism. Instead, caspase-8 cleavage was slightly preceded by activation of caspase-3, suggesting that drug-induced caspase-8 activation in B-lymphoma cells is a downstream event mediated by other caspases. This assumption was confirmed in 2 experimental systems-zDEVD-fmk, a cell-permeable inhibitor of caspase-3-like activity, blocked drug-induced caspase-8 cleavage, and depletion of caspase-3 from cell extracts impaired caspase-8 cleavage after in vitro activation with dATP and cytochrome c. Thus, these data indicate that drug-induced caspase-8 activation in B-lymphoma cells is independent of death receptor signaling and is mediated by postmitochondrial caspase-3 activation.

Constitutive NF-kappaB maintains high expression of a characteristic gene network, including CD40, CD86, and a set of antiapoptotic genes in Hodgkin/Reed-Sternberg cells

Constitutively activated nuclear factor (NF)-kappaB is observed in a variety of neoplastic diseases and is a hallmark of the malignant Hodgkin and Reed-Sternberg cells (H/RS) in Hodgkin lymphoma. Given the distinctive role of constitutive NF-kappaB for H/RS cell viability, NF-kappaB-dependent target genes were searched for by using adenoviral expression of the super-repressor IkappaBDeltaN. A surprisingly small but characteristic set of genes, including the cell-cycle regulatory protein cyclin D2, the antiapoptotic proteins Bfl-1/A1, c-IAP2, TRAF1, and Bcl-x(L), and the cell surface receptors CD86 and CD40 were identified. Thus, constitutive NF-kappaB activity maintains expression of a network of genes, which are known for frequent, marker-like expression in primary or cultured H/RS cells. Intriguingly, CD40, which is able to activate CD86 or Bcl-x(L) via NF-kappaB, is itself transcriptionally regulated by NF-kappaB through a promoter proximal binding site. NF-kappaB inhibition resulted in massive spontaneous and p53-independent apoptosis, which could be rescued by ectopic expression of Bcl-x(L), underscoring its dominant role in survival of H/RS cells. Hence, NF-kappaB controls a signaling network in H/RS cells, which promotes tumor cell growth and confers resistance to apoptosis.

Expression of the bcl-2 gene family in normal and malignant breast tissue: low bax-alpha expression in tumor cells correlates with resistance towards apoptosis

We have studied the expression of the apoptosis-regulating genes bcl-2, bcl-x, bax and APO-1/fas (CD95) in human breast cancer. The expression pattern of these genes in human breast-cancer tissues and breast-cancer-derived cell lines was compared to that seen in normal breast epithelium and breast epithelial cell lines. No difference with regard to bcl-2 and bcl-xL expression was observed between normal breast epithelium and tumor tissue or breast cancer and non-malignant epithelial cell lines. In contrast, bax-alpha, a splice variant of bax, which promotes apoptosis, is expressed in high amounts in normal cell lines and breast tissue, whereas only weak or no expression could be detected in cancer-cell lines and malignant tissue. In contrast to malignant cell lines, which express low levels of bax-alpha, non-malignant epithelial cell lines displaying high amounts of bax-alpha were highly sensitive to induction of programmed cell death by both serum starvation and APO-1/fas (CD95) triggering. We therefore propose that dysregulation of apoptosis contributes to the pathogenesis of breast cancer, at least in part, due to an imbalance between anti-apoptosis genes (such as bcl-2/bcl-x) and apoptosis-promoting genes (bax).

Effect of anti-CD 20 antibody rituximab in patients with post-transplant lymphoproliferative disorder (PTLD)

Post-transplant lymphoproliferative disorders (PTLD) are a life-threatening complication following solid organ transplantation. Treatment with rituximab, a humanized anti-CD20 monoclonal antibody, has proved to be a promising approach and shown a low toxicity profile. Between February 1999 and April 2002, we conducted a multicentre phase II trial investigating rituximab as single agent in 17 patients with PTLD. Transplanted organs were heart (n = 5), kidney (n = 4), lung (n = 4) and liver (n = 4). Patients were treated with four weekly doses of 375 mg/m(2) of rituximab. The mean follow-up time is 24.2 months. Histology was distributed in 10 diffuse large cell-, 2 marginal zone-, 1 Burkitt-like lymphoma, 1 Hodgkin-like PTLD and 3 polymorphic lymphoproliferations. Therapy was well tolerated and no severe adverse events were observed. The mean overall survival period is 37.0 months with 11 patients still living. In total, 9 patients (52.9%) achieved a complete remission, with a mean duration of 17.8 months. Partial remission was observed in 1 patient, minor remission in 2 patients, no change in 3 patients and 1 patient experienced progressive disease. Two patients relapsed, at intervals 3 and 5 months after obtaining complete remission. Rituximab proved to be well tolerated and effective in the treatment of PTLD.

Antisense therapy in oncology: new hope for an old idea?

There is a potential role for antisense oligonucleotides in the treatment of disease. The principle of antisense technology is the sequence-specific binding of an antisense oligonucleotide to target mRNA, resulting in the prevention of gene translation. The specificity of hybridisation makes antisense treatment an attractive strategy to selectively modulate the expression of genes involved in the pathogenesis of diseases. One antisense drug has been approved for local treatment of cytomegalovirus-induced retinitis, and several antisense oligonucleotides are in clinical trials, including oligonucleotides that target the mRNA of BCL2, protein-kinase-C alpha, and RAF kinase. Antisense oligonucleotides are well tolerated and might have therapeutic activity. Here, we summarise treatment ideas in this field, summarise clinical trials that are being done, discuss the potential contribution of CpG motif-mediated effects, and look at promising molecular targets to treat human cancer with antisense oligonucleotides.

Towards a better definition of human leucocyte surface molecules

At the 4th International Workshop on Human Leucocyte Differentiation Antigens workers from 525 laboratories jointly evaluated and/or submitted about 1100 different monoclonal antibodies to human leucocyte surface molecules. At the final conference of the workshop agreement was reached on 35 new cluster determinants (CDs) and subclusters. In addition, seven previously established clusters were redefined. This report provides basic information concerning the molecules defined by these antibodies and some highlights of the conference.

Time-intensified dexamethasone/cisplatin/cytarabine: an effective salvage therapy with low toxicity in patients with relapsed and refractory Hodgkin's disease

BACKGROUND

An important variable affecting outcome in relapsed and refractory Hodgkin's disease (HD) is the potential of conventional salvage chemotherapy to reduce tumor volume before high-dose chemotherapy (HDCT) and autologous stem cell transplantation. Currently, the optimal salvage chemotherapy regimen for these patients is unclear. Since dexamethasone/cisplatin/cytarabine (DHAP) given at 3-4 week intervals has been shown to be very effective in patients with relapsed aggressive non-Hodgkin's lymphoma, we evaluated this regimen given at a median of 16-day intervals in patients with relapsed and refractory HD.

PATIENTS AND METHODS

Patients with relapsed or refractory HD were treated with two cycles of DHAP [dexamethasone 40 mg intravenously (i.v.) day 1-4, cisplatin 100 mg/m(2) i.v. as 24-h continuous infusion day 1, and cytarabine 2 g/m(2) i.v. 12q day 2]. Granulocyte colony-stimulating factor (G-CSF) was given at a dose of 5 micro g/kg from day 4 until day 13. Patients with partial remission (PR) or complete remission (CR) after two cycles of DHAP received sequential HDCT.

RESULTS

The median age of the 102 patients included was 34 years (range 21-64 years). Forty-two percent of the patients had late relapse, 29% early relapse, 12% multiple relapse and 16% primary progressive/refractory disease. The response rate (RR) after two cycles of DHAP was 89% (21% CR, 68% PR). The RRs for patients with late, early, multiple and progressive HD were 91%, 93%, 92% and 65%, respectively. Using the chi-square test for independence, remission status (relapsed HD versus progressive HD) and stage at relapse (stage I/II versus stage III/IV) were significant factors for response to DHAP. WHO grade 4 leukocytopenia and thrombocytopenia were the main toxic- ities occurring in 43% (mean duration 1.1 days, range 0-6) and 48% (mean duration 1.4 days, range 0-11) of all courses, respectively. Neither severe infections nor treatment-related deaths occurred. Peripheral blood stem cells (PBSCs) were collected after the first cycle DHAP in eight patients. The hematopoietic progenitors showed a very rapid increase from day 10 with a synchronous and impressive peak on day 12. A mean of 6.1 x 10(6)/kg CD34(+) cells were collected per apheresis. As originally recommended in the protocol, PBSCs were routinely collected during sequential HDCT in the remaining patients.

CONCLUSIONS

A brief tumor-reducing program with two cycles of DHAP given in short intervals supported by G-CSF is effective and well-tolerated in patients with relapsed and refractory HD. This regimen can be used to mobilize stem cells and select those patients with chemosensitive relapse who should subsequently be treated with HDCT.

Identification of apoptosis-associated proteins in a human Burkitt lymphoma cell line. Cleavage of heterogeneous nuclear ribonucleoprotein A1 by caspase 3

Apoptosis or programmed cell death is essential in the process of controlling lymphocyte growth and selection. We identified proteins that are involved in anti-IgM antibody-mediated apoptosis using a subclone of the human Burkitt lymphoma cell line BL60. Apoptosis-associated proteins were detected by high resolution two-dimensional gel electrophoresis on a micropreparative scale. Comparison of the high resolution two-dimensional gel electrophoresis protein patterns from apoptotic and non-apoptotic cells showed differences in approximately 80 spots including protein modifications. Analysis of the predominantly altered proteins was performed by internal Edman microsequencing and/or by peptide mass fingerprinting using matrix-assisted laser desorption/ionization mass spectrometry. Analysis was significantly improved by using new micropreparative high resolution two-dimensional gels employing high protein concentrations. The following 12 apoptosis-associated proteins were identified: heterogeneous nuclear ribonucleoprotein (hnRNP) A1, hnRNP C1/C2, FUSE-binding protein, dUTPase, lymphocyte-specific protein LSP1, UV excision repair protein RAD23 homologue B (HHR23B), 60 S acidic ribosomal protein P0 (L10E), heterochromatin protein 1 homologue alpha (HP1alpha), nucleolin, lamin, neutral calponin, and actin. Fragmentation of actin, hnRNP A1, hnRNP C1/C2, 60 S acidic ribosomal protein P0, lamin, and nucleolin could be inhibited by benzyloxycarbonyl-Asp(OMe)-Glu(OMe)-Val-Asp(OMe)-fluoromethyl ketone, a selective irreversible inhibitor of CPP32 (caspase 3).

Overexpression of the death-promoting gene bax-alpha which is downregulated in breast cancer restores sensitivity to different apoptotic stimuli and reduces tumor growth in SCID mice

We have studied the expression of members of the bcl-2 family in human breast cancer. The expression pattern of these genes in breast cancer tissue samples was compared with the expression pattern in normal breast epithelium. No marked difference with regard to bcl-2 and bcl-xL expression was observed between normal breast epithelium and cancer tissue. In contrast, bax-alpha, a splice variant of bax, which promotes apoptosis, is expressed in high amounts in normal breast epithelium, whereas only weak or no expression could be detected in 39 out of 40 cancer tissue samples examined so far. Of interest, downregulation of bax-alpha was found in different histological subtypes. Furthermore, we transfected bax-alpha into breast cancer cell lines under the control of a tetracycline-dependent expression system. We were able to demonstrate for the first time that induction of bax expression in breast cancer cell lines restores sensitivity towards both serum starvation and APO-I/Fas-triggered apoptosis and significantly reduces tumor growth in SCID mice. Therefore, we propose that dysregulation of apoptosis might contribute to the pathogenesis of breast cancer at least in part due to an imbalance between members of the bcl-2 gene family.

APO-1 mediated apoptosis or proliferation in human chronic B lymphocytic leukemia: correlation with bcl-2 oncogene expression

We studied induction of apoptosis in several human malignant B cells from chronic lymphocytic leukemias (BCLL) by triggering the APO-1 antigen. The APO-1 antigen was found to be expressed on the surface of malignant B cells. In BCLL cells from most patients, APO-1 antigen expression increased following in vitro activation by Staphylococcus aureus Cowan I (SAC) or interleukin-2 (IL-2). In certain cases of BCLL co-stimulation with SAC plus IL-2 resulted in a synergistic up-regulation of the APO-1 antigen on the cell surface and prepared BCLL cells for monoclonal antibody anti-APO-1 mediated apoptosis. Interestingly, bcl-2 mRNA expression decreased upon stimulation with SAC plus IL-2, whereas SAC or IL-2 alone did not affect the level of bcl-2 expression. Thus, in these BCLL cells induction of anti-APO-1-mediated apoptosis appeared to be correlated with bcl-2 mRNA down-regulation. One informative BCLL, however, with a similar pattern of APO-1-antigen expression, did not show SAC plus IL-2-dependent bcl-2 down-regulation. Surprisingly, these cells proliferated in response to anti-APO-1 only when cells were co-stimulated with SAC plus IL-2. Our data suggest that down-regulation of bcl-2 prepares BCLL cells for induction of APO-1-mediated apoptosis. In addition they demonstrate that triggering of the APO-1 antigen may also lead to the induction of proliferation in special cases of BCLL.

Cologne high-dose sequential chemotherapy in relapsed and refractory Hodgkin lymphoma: results of a large multicenter study of the German Hodgkin Lymphoma Study Group (GHSG)

BACKGROUND

We designed a dose- and time-intensified high-dose sequential chemotherapy regimen for patients with relapsed and refractory Hodgkin lymphoma (HD).

PATIENTS AND METHODS

Eligibility criteria included age 18-65 years, histologically proven primary progressive (PD) or relapsed HD. Treatment consisted of two cycles DHAP (dexamethasone, high-dose cytarabine, cisplatinum); patients with chemosensitive disease received cyclophosphamide followed by peripheral blood stem cell harvest; methotrexate plus vincristine, etoposide and BEAM plus peripheral blood stem cell transplantation (PBSCT).

RESULTS

A total of 102 patients (median age 34 years, range 18-64) were enrolled. The response rate was 80% (72% complete response, 8% partial response). With a median follow-up of 30 months (range 3-61 months), freedom from second failure (FF2F) and overall survival (OS) were 59% and 78% for all patients, respectively. FF2F and OS for patients with early relapse were 62% and 81%, for late relapse 65% and 81%; for PD 41% and 48%, and for multiple relapse 39% and 48%, respectively. In multivariate analysis response after DHAP (P <0.0001) and duration of first remission (PD and multiple relapse versus early and late relapse; P=0.0127) were prognostic factors for FF2F. Response after DHAP (P <0.0081), duration of first remission (P=0.0017) and anemia (P=0.019) were significant for OS.

CONCLUSION

Based on the promising results of this study, a prospective randomized European intergroup study was started comparing this intensified regimen with two courses of DHAP followed by BEAM (HD-R2 protocol).

Analysis of the p53/BAX pathway in colorectal cancer: low BAX is a negative prognostic factor in patients with resected liver metastases

PURPOSE

To determine the prognostic value of the central downstream apoptosis effector BAX in relation to its upstream regulator p53 in R0-resected hepatic metastases of colorectal cancer.

PATIENTS AND METHODS

Retrospective analysis of 41 patients who underwent potentially curative resection of liver metastases from colarectal cancer was performed. Tumor DNA was screened for p53 mutations by single-stranded conformational polymorphism polymerase chain reaction and for BAX frameshift mutations by fragment length analysis. Protein expression of BAX, p21, and p53 was investigated by immunohistochemistry.

RESULTS

Overall median survival was 40.2 months. Tumors with BAX frameshift mutations were considered microsatellite mutator phenotype-positive and were excluded from further prognostic analyses. Patients with high BAX protein expression had a median survival of 53.6 months compared with 35.4 months for patients with low BAX expression (P < .05). The negative prognostic value of low BAX expression was more evident in those patients with wild-type p53 (median survival, 54.0 v 23.3 months for BAX-negative tumors; P < .01). Low BAX expression was an independent negative prognostic marker in multivariate regression analysis for all patients independent of the p53 status (relative risk, 3.03, P = .03), especially for p53 wild-type tumors (relative risk, 8.21; P = .0095).

CONCLUSION

We conclude that low BAX expression is an independent negative prognostic marker in patients with hepatic metastases of colorectal cancer. The best survival was seen in patients with an intact p53-to-BAX pathway; ie, wild-type p53- and BAX-positive tumors. Thus, analysis of apoptosis signaling pathways (here, p53 in concert with its downstream death effector, BAX) might yield more prognostic power in future studies as compared with analysis of single genes such as p53 alone.

Piceatannol, a hydroxylated analog of the chemopreventive agent resveratrol, is a potent inducer of apoptosis in the lymphoma cell line BJAB and in primary, leukemic lymphoblasts

The stilbene phytochemicals resveratrol and piceatannol have been reported to possess substantial antitumorigenic and antileukemic activities, respectively. Although recent experimental data revealed the proapoptotic potency of resveratrol, the molecular mechanisms underlying the antileukemic activity have not yet been studied in detail. In the present study, we show that resveratrol, as well as the hydroxylated analog piceatannol, are potent inducers of apoptotic cell death in BJAB Burkitt-like lymphoma cells with an ED50 concentration of 25 microM. Further experiments revealed that treatment of BJAB cells with both substances led to a concentration-dependent activation of caspase-3 and mitochondrial permeability transition. Using BJAB cells overexpressing a dominant-negative mutant of the Fas-associated death domain (FADD) adaptor protein to block death receptor-mediated apoptosis, we demonstrate that resveratrol- and piceatannol-induced cell death in these cells is independent of the CD95/Fas signaling pathway. To explore the antileukemic properties of both compounds in more detail, we extended our study to primary, leukemic lymphoblasts. Interestingly, piceatannol but not resveratrol is a very efficient inducer of apoptosis in this ex vivo assay with leukemic lymphoblasts of 21 patients suffering from childhood lymphoblastic leukemia (ALL).

Apoptosis-induced cleavage of beta-catenin by caspase-3 results in proteolytic fragments with reduced transactivation potential

Beta-catenin is a member of the Armadillo repeat protein family with a dual cellular function as a component of both the adherens junction complex and the Wnt/wingless signaling pathway. Here we show that beta-catenin is proteolytically cleaved during anoikis and staurosporine-induced apoptosis. Cleavage of beta-catenin was found to be caspase-dependent. Five cleavage products of beta-catenin were identified in vivo and after in vitro cleavage by caspase-3. Amino acid sequencing and mass spectrometry analysis indicated two caspase-3 cleavage sites at the C terminus and three further sites at the N terminus, whereas the central Armadillo repeat region remained unaffected. All beta-catenin cleavage products were still able to associate with E-cadherin and alpha-catenin and were found to be enriched in the cytoplasm. Functional analysis revealed that beta-catenin deletion constructs resembling the observed proteolytic fragments show a strongly reduced transcription activation potential when analyzed in gene reporter assays. We therefore conclude that an important role of the beta-catenin cleavage during apoptosis is the removal of its transcription activation domains to prevent its transcription activation potential.

Relapse in childhood acute lymphoblastic leukemia is associated with a decrease of the Bax/Bcl-2 ratio and loss of spontaneous caspase-3 processing in vivo

Dysfunction of the p53/Bax/caspase-3 apoptosis signaling pathway has been shown to play a role in tumorigenesis and tumor progression, ie the development of acquired drug resistance. Low expression of the apoptosis inducer Bax correlates with poor response to therapy and shorter overall survival in solid tumors. In the present study, we analyzed the p53/Bax/caspase-3 pathway in a paired and an unpaired sample series of children with acute lymphoblastic leukemia (ALL) at initial diagnosis and relapse. The data demonstrate that both Bax expression levels and the Bax/Bcl-2 ratio are significantly lower in samples at relapse as compared with samples at initial diagnosis (P=0.013, Wilcoxon signed rank test (paired samples); P=0.0039, Mann-Whitney U test (unpaired samples)). The loss of Bax protein expression was not a consequence of Bax frameshift mutations of the G8 tract and could not be attributed to mutations of the p53 coding sequence (exons 5 to 8) which were detected to a similar extent in de novo ALL samples and at relapse. Analysis of the downstream effector caspase-3 showed loss of spontaneous caspase-3 processing at relapse. Whereas nine out of 14 (64%, paired samples) or 37 out of 77 (48%, unpaired samples) ALL patients at initial diagnosis displayed spontaneous in vivo processing of caspase-3, this was completely absent in patients at relapse (paired samples) or detected in only one out of 34 patients at relapse (2.9%, unpaired samples). We therefore conclude that in ALL relapse a severe disturbance of apoptotic pathways occurs, both at the level of Bax expression and caspase-3 activation.

Reactivation of hepatitis E infection in a patient with acute lymphoblastic leukaemia after allogeneic stem cell transplantation

Hepatitis E virus (HEV) is the major cause of several outbreaks of waterborne hepatitis in tropical and subtropical countries and of sporadic cases of viral hepatitis in endemic and industrialised countries. Generally, HEV causes an acute self-limiting hepatitis. The clinical course is characterised by transient viraemia and transaminasaemia followed by a full hepatic recovery. Recent studies describe prolonged and chronic HEV infections in some immunosuppressed patients after solid organ transplantation. Here, an indigenous acute limited hepatitis E in a patient with Philadelphia chromosome-positive acute lymphoblastic leukaemia prior to allogeneic stem cell transplantation is reported. Fourteen weeks after stem cell transplantation, reappearance of HEV viraemia was observed, with increasing viral load and modestly elevated serum transaminases. Sequence analysis of the viral RNAs revealed a reactivation of endogenous HEV genotype 3, indicating viral persistence after recovery from acute hepatitis E.

Efficient elimination of chronic lymphocytic leukaemia B cells by autologous T cells with a bispecific anti-CD19/anti-CD3 single-chain antibody construct

Recently, we have shown that a novel recombinant bispecific single-chain antibody construct (bscCD19 x CD3), induces highly efficacious lymphoma-directed cytotoxicity mediated by unstimulated peripheral T lymphocytes. Functional analysis of bscCD19 x CD3 has so far been exclusively performed with human B lymphoma cell lines and T cells from healthy donors. Here we analysed the properties of bscCD19 x CD3 using primary B cells and autologous T cells from healthy volunteers or patients with B-cell chronic lymphocytic leukaemia (B-CLL). We show that bscCD19 x CD3 induces T-cell-mediated depletion of nonmalignant B cells in all four cases and depletion of primary lymphoma cells in 22 out of 25 cases. This effect could be observed at low effector-to-target (E:T) ratios and in the majority of cases without additional activation of autologous T cells by IL-2. Even in samples derived from patients heavily pretreated with different chemotherapy regimens, strong cytotoxic effects of bscCD19 x CD3 could be observed. The addition of bscCD19 x CD3 to patients' cells resulted in an upregulation of activation-specific cell surface antigens on autologous T cells and elevated levels of CD95 on lymphoma B cells. Although anti-CD95 antibody CH-11 failed to induce apoptosis in lymphoma cells, we provide evidence that B-CLL cell depletion by bscCD3 x CD3 is mediated at least in part by apoptosis via the caspase pathway.

Mutation of p53 and consecutive selective drug resistance in B-CLL occurs as a consequence of prior DNA-damaging chemotherapy

Inactivation of p53 has been shown to correlate with poor prognosis and drug resistance in malignant tumors. Nevertheless, few reports have directly shown such effects in primary tumor cells. Here, we investigated the p53 mutational status in 138 B-CLL samples and compared these findings with drug and gamma-irradiation sensitivity profiles. p53 mutations resulted not only in a shorter survival but, notably also in selective resistance to alkylating agents, fludarabine and gamma-irradiation. In contrast, no such effect was observed for vincristine, anthracyclines and glucocorticoids. Thus, these latter compounds induce cell death at least in part by p53-independent pathways. Interestingly, p53 mutations clustered in patients who had received prior chemotherapy. In fact, we show for the first time that treatment with DNA-damaging alkylating agents correlates with occurrence of p53 mutations in a clinical setting. This finding may explain at least to some extent the development of resistance to second-line anticancer chemotherapy.

Effective biomodulation by leucovorin of high-dose infusion fluorouracil given as a weekly 24-hour infusion: results of a randomized trial in patients with advanced colorectal cancer

PURPOSE

To determine whether high-dose infusional fluorouracil (FU) is effectively modulated by leucovorin (LV), interferon (IFN) alpha-2b, or both when given to patients with metastatic colorectal cancer.

PATIENTS AND METHODS

Patients (n = 236) with progressive, measurable disease were randomized to three groups and received FU 2,600 mg/m2 as a 24-hour continuous infusion (CI) weekly for 6 weeks with 2 weeks rest (FU24h) and LV 500 mg/m2 as a 2-hour infusion before FU or IFN 3 x 10(6) U subcutaneously 3 times weekly or both. Treatment continued until progressive disease or unacceptable toxicity was observed. Pairs of treatment arms were analyzed sequentially to detect equivalence or a 25% difference in response rates.

RESULTS

The rate of objective remission in patients who received FU24h/LV (44%; 40 of 91) was significantly higher than in patients who received FU24h/IFN (18%; 16 of 90; P < .05). The response rates of patients who received FU24h/LV versus FU24h/LV/IFN (27%; 13 of 49) were statistically equivalent. Significant differences were observed for time to tumor progression (TTP) (FU24h/LV, 7.1 months; FU24h/IFN, 3.9 months; FU24h/LV/IFN, 6.3 months; global P value < .009) and survival (16.6 months, 12.7 months, 19.6 months, respectively; global P value < .04). Unpredictable and life-threatening toxicity in the FU24h/LV/IFN arm required dose reduction of FU to 2,000 mg/m2/day and early stoppage of this arm. Toxicity was manageable in patients who received both FU24h/LV (grade 3 to 4 diarrhea, 21%) and FU24h/IFN (grade 3 to 4 diarrhea, 15%).

CONCLUSION

Response rate, TTP, and overall survival were superior for LV-containing regimens compared with IFN modulation alone. The addition of IFN to high-dose infusional FU plus LV offers no advantage and may increase toxicity. The regimen of high-dose infusional FU24h/LV warrants further evaluation in patients with metastatic colorectal cancer.

Apoptosis: implications of basic research for clinical oncology

Recent studies have indicated a role for apoptosis in a variety of human diseases. Suppression of apoptosis contributes to carcinogenesis by several mechanisms, including facilitating the accumulation of gene mutations, permitting growth-factor-independent cell survival, promoting resistance to immune-based cytotoxicity, and allowing bypassing of cell-cycle checkpoints, which would normally induce apoptosis. Defects in apoptotic mechanisms also play an important part in resistance to chemotherapy and radiation. The core machinery of the cell death pathway can be reduced to a few critical types of proteins, which are well conserved across animal evolution. This review gives an update on the key players involved in apoptosis as well as an overview of the involvement of apoptosis in disease, and novel diagnostic and therapeutic options derived from the extensive basic research on this topic carried out over the last decade.

Anti-CD22 and anti-CD79B antibody drug conjugates are active in different molecular diffuse large B-cell lymphoma subtypes

Antibody drug conjugates (ADCs), in which cytotoxic drugs are linked to antibodies targeting antigens on tumor cells, represent promising novel agents for the treatment of malignant lymphomas. Pinatuzumab vedotin is an anti-CD22 ADC and polatuzumab vedotin an anti-CD79B ADC that are both linked to the microtubule-disrupting agent monomethyl auristatin E (MMAE). In the present study, we analyzed the activity of these agents in different molecular subtypes of diffuse large B-cell lymphoma (DLBCL) both in vitro and in early clinical trials. Both anti-CD22-MMAE and anti-CD79B-MMAE were highly active and induced cell death in the vast majority of activated B-cell-like (ABC) and germinal center B-cell-like (GCB) DLBCL cell lines. Similarly, both agents induced cytotoxicity in models with and without mutations in the signaling molecule CD79B. In line with these observations, relapsed and refractory DLBCL patients of both subtypes responded to these agents. Importantly, a strong correlation between CD22 and CD79B expression in vitro and in vivo was not detectable, indicating that patients should not be excluded from anti-CD22-MMAE or anti-CD79B-MMAE treatment because of low target expression. In summary, these studies suggest that pinatuzumab vedotin and polatuzumab vedotin are active agents for the treatment of patients with different subtypes of DLBCL.

Induction of gene expression by 5-Aza-2'-deoxycytidine in acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) but not epithelial cells by DNA-methylation-dependent and -independent mechanisms

The methylation inhibitor 5-Aza-2'-deoxycytidine (5-Aza-CdR, decitabine) has therapeutic efficacy in acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). Using microarray analysis, we investigated global changes in gene expression after 5-Aza-CdR treatment in AML. In the AML cell line OCI-AML2, Aza-CdR induced the expression of 81 out of 22 000 genes; 96 genes were downregulated (> or =2-fold change in expression). RT-PCR analysis of 10 randomly selected genes confirmed the changes of expression in AML cells. Similar results were obtained with primary AML and MDS cells after treatment with 5-Aza-CdR ex vivo and in vivo, respectively. In contrast, significantly fewer changes in gene expression and cytotoxicity were detected in normal peripheral blood mononuclear and bone marrow cells or transformed epithelial cells treated with 5-Aza-CdR. Interestingly, only 50.6% of the induced genes contain putative CpG islands in the 5' region. To further investigate the significance of promoter methylation in the induced genes, we analyzed the actual methylation status of randomly selected 5-Aza-CdR-inducible genes. We detected hypermethylation exclusively in the 5' region of the myeloperoxidase (MPO) gene. DNA methylation inversely correlated with MPO expression in newly diagnosed untreated AML patients (P< or =0.004). In contrast, all other analyzed 5-Aza-CdR-inducible genes revealed no CpG methylation in the promoter region, suggesting a methylation-independent effect of 5-Aza-CdR.