Introduction: Fludarabine plus rituximab (F-R) is an established treatment option for patients (pts) with relapsed/refractory follicular lymphoma (FL), other indolent lymphoma, or mantle cell lymphoma (MCL). To further improve the treatment in this setting we initiated in 2003 a multicenter, randomized phase III study to compare the efficacy and safety of bendamustine plus rituximab (B-R) versus F-R for pts with relapsed FL, other indolent lymphomas or MCL.

7501 Background: This multicenter, randomized, phase III study compared B-R and CHOP-R as first-line treatment in patients (pts) with indolent lymphomas or mantle cell lymphoma and was first published in The Lancet in 2013. The final analysis demonstrated a significantly prolonged progression-free survival (PFS) in the B-R group compared to the CHOP-R group, with a median PFS of 69.5 vs. 31.2 months, respectively. In the current analysis, we present updated results for overall survival (OS), time-to-next-treatment (TTNT), and secondary malignancies (sNPL) with a median follow-up of 113 months for patients with indolent lymphomas (excluding MCL). Methods: 447 pts with indolent lymphomas were randomized to receive B-R or CHOP-R for a maximum of 6 cycles. The primary endpoint was PFS; secondary endpoints included OS, TTNT, and sNPL. Results: Patient characteristics were well balanced between arms; median age was 64 years. The difference in OS between the two treatment arms was not statistically significant, with 60 deaths in the B-R group vs 68 deaths with CHOP-R (HR 0.82, 95% CI 0.58 – 1.15, p = 0.249). The estimated 10-year survival rates were 71% for B-R and 66% for CHOP-R. TTNT was significantly prolonged with B-R compared with CHOP-R (HR 0.52, 95% CI 0.38 – 0.69, p < 0.001). Median TTNT was not yet reached in the B-R group (95% CI 124.9 – n.y.r) vs. 56 months in the CHOP-R group (95% CI 39.1 – 82.0). Patients treated initially with B-R needed fewer second-line treatments due to disease progression compared to CHOP-R treated pts: 73 pts (34%) in the B-R group received salvage treatment compared with 106 pts (52%) in the CHOP-R group. For B-R pts, CHOP-R was used as second-line therapy 26 times (36%), whereas B-R was used for pts initially treated with CHOP-R 49 times (46%). 36 pts with sNPL were observed in the B-R group compared with 39 in the CHOP-R group, with 7 hematological malignancies in both groups to date. Conclusions: In pts with previously untreated indolent lymphomas, B-R demonstrates a PFS and TTNT benefit over CHOP-R. Clinical trial information: NCT00991211.

4035 Background: Pancreatic ductal adenocarcinoma (PDAC) is one of the most common malignant tumours, but PDAC is still associated with a poor prognosis in advanced disease with an overall 5-year survival of only about 15%. Therefore there is a need for new treatment strategies. To improve the standard therapy with gemcitabine we initiated a prospective randomized phase-II trial with gemcitabine (GEM) vs. gemcitabine plus sunitinib (SUNGEM) based on data of in vitro trials and phase-I data for the combination treatment. Methods: Patients (N=113) with locally advanced or metastatic PDAC were prospectively randomized to receive gemcitabine alone (GEM) at a dosage of 1000 mg/m² day 1, 8, 15 q28 or to a combination of gemcitabine and sunitinib (SUNGEM) at a dosage of GEM 1000 mg/m² d1+8 and sunitinib 50mg p.o. d1-14, qd21 (based on a phase-I trial). The primary endpoint was progression-free survival (PFS), secondary endpoints were overall survival (OS), time to progression (TTP), overall response rate (ORR) and toxicity. Results: The confirmatory analysis of PFS was based on the ITT population (N=106). The median PFS was 13.3 weeks (95 %-Cl: 10.4-18.1 weeks) in the GEM group and 11.6 weeks in the SUNGEM arm (95 %-Cl: 7.0-18.0 weeks) (one-sided logrank: p=0.74). The 6-month PFS rate was 26.8 % (95 %-Cl: 15.4-39.5 %) in GEM arm and 25.0 % in SUNGEM arm (95 %-Cl: 14.0-37.8 %). The overall response rate was 6.1 % (95 %-Cl: 0.7-20.2 %) in the GEM arm and was a slightly but not significantly higher for the SUNGEM arm with 7.1% (95%-Cl: 0.9 – 23.5%).The median time to progression (TTP) was 14.0 weeks (95 %-Cl: 12.4-22.3 weeks) for the GEM arm and 18.0 weeks (95 %-Cl: 11.3-19.3 weeks) for the SUNGEM arm (two-sided logrank: p=0.60). The median OS was 30.4 weeks (95 %-Cl: 18.1-37.6 weeks) for the SUNGEM and 36.7 weeks (95 %-Cl: 20.6-49.0 weeks) for the GEM arm (two-sided logrank: p=0.44). With regard to toxicities, at least one AE of grade 3 or 4 was reported in 78.8% in the SUNGEM arm and 72.2% in the GEM arm. Conclusions: The combination of gemcitabine plus sunitinib (SUNGEM) did not improve the PFS in locally advanced or metastatic PDAC compared to gemcitabine alone. Clinical trial information: NCT00673504.

BACKGROUND Rituximab plus combination chemotherapy with cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) is widely recommended for the treatment of aggressive B-cell lymphomas. However, there is very little information regarding the management of elderly patients. PATIENTS AND METHODS We initiated a phase II study of first-line treatment with rituximab and bendamustine in elderly patients (≥80 years) with aggressive B-cell lymphomas who were not eligible for R-CHOP or who did not agree to aggressive treatment. The treatment decision on eligibility for R-CHOP was left to discretion of the physicians. RESULTS Fourteen patients with a median age of 85 years (range 80-95 years) were included. The age-adjusted international prognostic index was zero in five patients, one in three patients, and two in six patients. Thirteen patients were assessable for response. Seven patients (54%) had a complete response, two (15%) a partial response, and four (31%) progressive disease. The median overall survival was 7.7 months, and the median progression-free survival 7.7 months; however, six patients (43%) were alive without disease at 20-72 months from the start of treatment. Major toxicity was neutropenia (17% grade 3 and 6% grade 4). All other grade 3 and 4 hematotoxicities and non-hematological toxic effects ranged between 2% and 11% CONCLUSIONS Because of its efficacy and low toxicity, bendamustine in combination with rituximab may be an alternative treatment for aggressive lymphomas in old patients not eligible for R-CHOP. These results, however, need to be confirmed in larger studies.

The CXCR4-inhibitor plerixafor mobilizes hematopoietic stem cells amplifying the effects of granulocyte-CSF (G-CSF). Before approval plerixafor was used in a compassionate use program (CUP) for patients who failed a previous mobilization. In the German CUP 60 patients from 23 centers (median age 56.5 years (2–75)) were given 240 μg/kg plerixafor SC 9–11 h before apheresis. A total of 78.3% (47/60) received G-CSF for 4 days before plerixafor administration; 76.6% of those (36/47) yielded at least 2.0 × 106 CD34+ cells/μL. The median cell yield was 3.35 × 106 CD34+ cells/kg (0–29.53). Nine patients received plerixafor alone or with G-CSF for less than 4 days mobilizing a median of 3.30 × 106 CD34+ cells/kg (1.6–5.6). There was no significant difference between G-CSF application for 4 days and for a shorter period of time (P=0.157). A total of 47 patients received plerixafor plus G-CSF combined with chemotherapy yielding a median of 3.28 × 106 CD34+ cells/kg (0–24.79). In all, 40 of 60 patients (66.7%) proceeded to transplantation, and achieved a timely and stable engraftment. Side effects were rare and manageable. In conclusion, mobilization with plerixafor in poor mobilizers is safe and results in a sufficient stem cell harvest in the majority of patients.

Valproic acid has been demonstrated to mediate cytotoxic effects against tumor cells by acting as a histone-deacetylase inhibitor. However, to date, there are only limited data on the effects of valproic acid in colon cancer. Moreover, information regarding combinations of the drug with chemotherapeutic agents is very limited. The latter is of interest as there is increasing evidence for synergism between so-called "molecular targeting drugs" and chemotherapy. We first demonstrated that valproic acid dose-dependently reduced the viability of adenocarcimona cell lines. After co-incubation with a variety of chemotherapeutic agents, only valproic acid in combination with mitomycin C consistently induced synergistic growth inhibition in all cell lines. To confirm these results in an ex vivo situation, five samples of fresh colon cancer cells were studied. Again, the effect of valproic acid on the viability of the fresh tumor cells was dose dependent. In four of five samples of freshly isolated colon cancer cells, the synergistic effect of valproic acid and mitomycin C on the inhibition of cell growth was confirmed by calculation of the combination index by multiple drug effect analysis. In conclusion, this is the first demonstration that valproic acid as a model substance for histone-deacetylase inhibitors is effective in tumor cells freshly isolated from patients with colon cancer and that the combination of mitomycin C and valproic acid synergistically decreases viability of colon cancer cells.

BACKGROUND:The role of Daxx, in particular its ability to promote or hinder apoptosis, still remains controversial. In order to elucidate the functional relevance of Daxx in the extrinsic signaling of malignant lymphocytes Jurkat T-cells were stably transfected with a Daxx-expressing vector or with the respective Daxx-negative control vector. RESULTS:Assessing first the impact of Daxx expression on the rate of proliferation we demonstrate that overexpression of Daxx alone is not sufficient to alter proliferation in neoplastic lymphocytes. Nevertheless, expression of Daxx down-regulates anti-apoptotic Bcl-2 and up-regulates pro-apoptotic BID. In addition, Daxx-overexpressing Jurkat cells exhibit a decreased expression of the pro-caspase-8, -10, -9 and -3 and a concomitant increase of the inhibitors of apoptosis proteins survivin, XIAP, cIAP-1 and -2. We further demonstrate, that upon incubation with various chemotherapeutic agents these Daxx-induced molecular alterations sensitize Jurkat T-cells to the apoptosis-inducing effects of specific chemotherapeutic agents. CONCLUSIONS:We here outline the molecular changes elicited by Daxx on major components of the apoptotic cascade of malignant lymphocytes and demonstrate the capacity of Daxx to sensitize these cells to the apoptosis-inducing effect of various chemotherapeutic agents.

The mutational status of immunoglobulin variable region genes (Ig VH) is a well established prognostic parameter in chronic lymphocytic leukemia (CLL). Recently, a subset of genes with a characteristic expression profile correlating with the mutational status of B-CLLs has been identified. One of the overexpressed genes in the prognostically unfavorable group of CLL patients with unmutated Ig VH genes encodes for the protein tyrosine kinase ZAP-70, which is physiologically involved in T-cell signaling. Since ZAP-70 has been described to be prognostically relevant in CLL, we analyzed the possible relationship of its expression to the mutational status of Ig VH genes as well as to other prognostic factors in CLL and indolent lymphomas. The mutational status of Ig VH genes was analyzed by seminested PCR, direct sequencing and comparison with the sequences of the EMBL databases in 60 samples of patients with B-CLL and 18 samples of patients with indolent B-cell malignancies. ZAP-70 protein expression was assessed in all samples by immunoblotting and for semiquantitative analysis the ratio of ZAP-70 to tubulin expression was calculated. ZAP-70 protein was found to be expressed in all investigated B-cell malignancies. Expression levels varied within a wide range in each entity. The highest mean level of ZAP-70 expression was observed in unmutated B-CLLs, however, with broad expression variability. High levels of ZAP-70 expression correlated with higher stage Binet B or C and with unmutated Ig VH genes. Overall survival rates estimated by Kaplan-Meier curves did not differ among patients with high or low ZAP-70 expression. We conclude that ZAP-70 is associated with the mutational status of Ig VH genes, but this expression pattern is not present in all individual cases. Furthermore, high levels of ZAP-70 correlated with Binet stages B or C indicating an involvement of ZAP-70 in mechanisms promoting growth of B-CLL cells.

In a variety of malignant cells the prostate-apoptosis-response-gene-4 (Par-4) induces increased sensitivity towards chemotherapeutic agents by down-regulating anti-apoptotic B-cell lymphoma-gene 2 (Bcl-2). Hypothesizing that Par-4 also influences apoptosis in myeloid cell lines, we tested this hypothesis by stably transfecting bcr-abl transformed-K562 cells with a Par-4-expressing vector. Here we demonstrate that over-expression of Par-4 in K562 cells up-regulates expression levels of Bcl-2 and death-associated protein (Daxx). Upon treatment with different chemotherapeutic agents, Fas- or TRAIL agonistic antibodies, Par-4-positive cells did not exhibit an increased rate of apoptosis as compared to Par-4-negative control cells. However, incubation with histone deacetylase (HDAC)-inhibitors Trichostatin A (TSA) and LAQ824 or the tyrosinkinase inhibitor Imatinib (STI571) increased the rate of apoptosis in Par-4-positive K562 cells. Assessing the underlying molecular mechanisms for the Par-4-induced response to HDAC-inhibitors and STI571 we provide evidence, that these effects are associated with a down-regulation of Daxx, enforced activation of caspases and enhanced cleavage of cellular inhibitor of apoptosis (cIAP)-1 and -2.

Peripheral (mature) T-cell lymphomas (PTCL) are represented by distinct lymphoma entities, many of which with a rather unfavourable clinical outcome as compared to B-cell lymphomas. Standard treatment regimens have not been established, except in primary cutaneous T-cell lymphomas (PCTCL). With regard to the unfavourable prognosis we designed a treatment protocol using chemoimmunotherapy in peripheral T-cell lymphomas except PCTCL and ALK-positive large cell anaplastic T-cell lymphomas, consisting of alemtuzumab 3, 10, 30, 30 mg, days 1–4, fludarabine (Flu) 25 mg/m2 days 2–4, cyclophosphamide (CP) 600 mg/m2 day 3, and doxorubicin (Dox) 50 mg/m2 day 4. Included were patients with primary diagnosis or with first or second relapse. Rationales for this regimen were proven efficacy of CP and Dox in T-cell lymphomas, high efficacy of Flu and CP (FC) in other lymphomas and the possible synergism of antibodies with cytotoxic drugs. So far, 23 patients have been included, 18 are evaluable for response and toxicity. Of the latter, 10 patients were diagnosed with PTCL-NOS, 5 with AILD, one with enteropathy-associated T-cell lymphoma, one with NK-cell lymphoma, and one with T-PLL. 9 patients were enrolled with primary diagnosis and 9 patients in relapse. The median age was 60 years (range 21–77); the median non-age adjusted IPI 2.5 (0–4), 2 in patients with primary diagnosis and 3 in patients with relapse. The overall response rate was 61% (11/18). In patients with primary diagnosis the CR rate was 78% (7/9), one patient achieved no change, and one patient died from treatment associated complications before response could be evaluated. All responding patients are in ongoing CR at 2+, 2+, 6+, 11+, 15+,16+, and 17+ months. In the group of relapsed patients one CR and 3 PR (44%) were observed. The main toxicity was leukocytopenia (81% grade III and IV of all evaluable treatment cycles), other grade III and IV toxicities included anemia (18%), thrombocytopenia (39%), infections (18%) nausea/emesis (9%), and allergic reactions (4%). Ten (56%) patients reactivated CMV without CMV-related disease and one patient with suspected CMV-peumonia. In conclusion, this is the first study demonstrating that alemtuzumab can be integrated into a triple-agent chemotherapy regimen. The combination is effective in the first-line treatment of peripheral T-cell lymphomas, however, regarding the general outcome a longer follow-up period of a larger patient population is required.

The role of Daxx, in particular its ability to promote or hinder proliferation, still remains controversial. In order to elucidate the functional relevance of Daxx in malignant myelocytes, the erythroleukemia cell line HEL was stably transfected with a Daxx-expressing vector or with the respective Daxx-negative control vector. Assessing the molecular consequences of ectopic Daxx-expression, we present evidence that Daxx downregulates p53. Moreover, we demonstrate that Daxx overexpressing myelocytes downregulate the proapoptotic Bcl-2 family member Bax, while expression of antiapoptotic Bcl-2 is not influenced. Furthermore, expression of Daxx diminishes expression levels of the initiator-procaspase-8 and -10, and the executioner procaspase-7, whereas the procaspase-3, -6 and -9 remain unaltered. The altered protein levels of the caspases in Daxx overexpressing myelocytes are accompanied by a decrease of expression levels of the inhibitor of apoptosis proteins (IAPs) cIAP-1, -2 and survivin. Despite the described impact of Daxx expression on major molecules of the apoptotic cascade, expression of Daxx in neoplastic myelocytes does not impact on the rate of proliferation. Upon a proapoptotic stimulus such as serum withdrawal Daxx is unable to maintain its influence on expression levels of p53, Bax, IAPs and the procaspase-8, -10 and -7.

Objective. Prostate apoptosis response gene-4 (par-4) is deregulated in acute and chronic lymphatic leukemia. Given its pro-apoptotic role in neoplastic lymphocytes and evidence that par-4 antagonizes oncogenic Ras in solid tumors, we hypothesized that par-4 may act as a tumor suppressor impairing transformation induced by p185(BCR-ABL).Materials and Methods. The capacity of par-4 to interfere with factor independence induced by P185(BCR-ABL) and V12ras was evaluated by analysis of factor-independent growth of p185(BCR-ABL)/ par-4 and V12ras/par-4 tranduced cells. The expression of par-4 and p185(BCR-ABL) by the respective constructs was controlled by Western blot analysis. Activated Ras was detected by pull-down assay in the cell clones expressing p185(BCR-ABL) in the absence and presence of par-4.Results. Expression of p185(BCR-ABL) causes factor independence, signifying a conversion toward a transformed phenotype in hematopoietic precursors. We demonstrate that par-4 completely abolishes factor independence induced by p185(BCR-ABL) and partially abrogates factor independence caused by activated V12ras. Evaluating the underlying molecular mechanisms, we show that par-4 hinders activation of oncogenic Ras and causes concomitant disruptions of p185 (BCR-ABL)- mediated signaling.Conclusion. We provide the first evidence that par-4 exhibits an antitransforming capacity by antagonizing p185(BCR-ABL)-induced factor-independent proliferation in hematopoietic cells. @ 2004 International Society for Experimental Hematology. Published by Elsevier Inc.

IntroductionPeripheral T-cell lymphomas (PTCL) according to the REAL classification (mature T-cell lymphomas of the WHO classification) comprise no more than 10% of all non-Hodgkin’s lymphomas in the Western hemisphere [1.Armitage J.O. Weisenburger D.D. New approach to classifying non-Hodgkin’s lymphomas: clinical features of the major histologic subtypes. Non-Hodgkin’s Lymphoma Classification Project.J Clin Oncol. 1998; 16: 2780-2795Crossref PubMed Scopus (1010) Google Scholar]. Until now, uncertainties regarding many features of these rather heterogeneous diseases have prevented progress in developing effective therapies. PTCL has often been assessed as part of clinical studies focusing on the more common B-cell lymphomas and, consequently, our understanding of how to treat this group of lymphomas remains less clear than for B-cell lymphomas.With the exception of a few subgroups, the prognosis of PTCL is poor, partly due to a limited understanding of their pathophysiological features. There is considerable variability in clinical presentation, which may greatly prolong the time taken to reach an accurate diagnosis in an individual patient. Additionally, treatment standards in PTCL have not yet been established [2.Armitage J.O. Canellos G.P. Lister T.A. Sklar J.L. The Lymphomas Peripheral T-cell lymphoma. WB Saunders, Philadelphia, PA1998: 439-448Google Scholar].Challenged by this variety of problems, the authors of this report organized a workshop in Schlangenbad, Germany, in late September 2002. Investigators from different backgrounds, including biology, pathology, molecular biology and genetics, dermatology, and hematology/oncology, presented and discussed updated knowledge and their own data on a variety of topics relating to PTCL, within sessions on immunology and histological classification; cytogenetics and molecular genetics; treatment of primary cutaneous and disseminated T-cell lymphomas; antibody treatment of T-cell malignancies; and recently published, current studies in PTCL. The aim of the workshop was to begin coordinating activities in experimental and clinical research in this group of lymphomas. This meeting report summarizes the main statements and conclusions of each session.Immunology and histological classificationThe workshop opened with a review of the biology of T and natural killer (NK) cells, by D. Kabelitz (Kiel). T cells bearing the αβ T-cell receptor (TCR) represent ∼95% of peripheral T cells, and recognize processed antigen presented as peptides either by major histocompatibility complex (MHC) class I molecules to CD8+ or by class II molecules to CD4+ cells. In contrast, most TCR γδ T cells recognize low molecular weight phosphorylated metabolites derived from the bacterial biosynthesis pathway, and are thus important for immune defense against bacterial infections [3.Kabelitz D. Glatzel A. Wesch D. Antigen recognition by human gammadelta T lymphocytes.Int Arch Allergy Immunol. 2000; 122: 1-7Crossref PubMed Scopus (92) Google Scholar]. Besides the TCR level, there is considerable functional heterogeneity among T cells. For example, CD4+ cells can be functionally divided into T helper 1 and 2, according to their spectrum of cytokine expression. More recently, regulatory T cells mediating suppressive effects have been described, which are defined by the expression of the interleukin (IL)-2 receptor α chain and IL-10, as well as transforming growth factor (TGF)-β [4.Nelson B.H. Interleukin-2 signaling and the maintenance of self-tolerance.Curr Dir Autoimmun. 2002; 5: 92-112Crossref PubMed Google Scholar]. NK cells do not express TCRs on their surface, but do express a group of C-type lectin and immunoglobulin-like receptors, the so-called ‘killer’ inhibitory receptors (KIR), which bind to human leukocyte antigen (HLA) class I molecules (e.g. HLA-C, HLA-E) and mediate inhibiting or activating signals. The discovery of these MHC class I receptors has considerably enhanced our understanding of the biology of NK cells. Up to seven different KIR can be expressed on a single NK cell. Preliminary new data indicate that accurate typing of HLA and KIR may have an important role in transplantation, especially in haploidentical settings [5.Davies S.M. Ruggieri L. DeFor T. et al.Evaluation of KIR ligand incompatibility in mismatched unrelated donor hematopoietic transplants. Killer immunoglobulin-like receptor.Blood. 2002; 100: 3825-3827Crossref PubMed Scopus (324) Google Scholar].M.-L. Hansmann (Frankfurt) presented insights into the molecular pathology of angioimmunoblastic T-cell lymphoma (AILD), a disease that is currently defined as a PTCL, although certain cases lack any clonality of CD4+ and CD8+ populations. In AILD with clonal expansion of CD4+ cells, Hansmann and co-workers [6.Willenbrock K. Roers A. Seidl C. et al.Analysis of T-cell subpopulations in T-cell non-Hodgkin’s lymphoma of angioimmunoblastic lymphadenopathy with dysproteinemia type by single target gene amplification of T cell receptor-beta gene rearrangements.Am J Pathol. 2001; 158: 1851-1857Abstract Full Text Full Text PDF PubMed Scopus (41) Google Scholar] detected overexpression of certain TCR Vβ segments, possibly suggesting that a superantigen trigger causes some cases of the disease [7.Rudiger T. Weisenburger D.D. Anderson J.R. et al.Peripheral T-cell lymphoma (excluding anaplastic large-cell lymphoma): results from the Non-Hodgkin’s Lymphoma Classification Project.Ann Oncol. 2002; 13: 140-149Abstract Full Text Full Text PDF PubMed Scopus (371) Google Scholar]. Moreover, Hansmann presented new data explaining the clonal expansion of B cells in AILD, resulting in so-called ‘forbidden B cells’. Single-cell studies in B cells, which are frequently infected with the Epstein–Barr virus (EBV) in AILD, revealed oligoclonal or sometimes large clonal expansions of these cells. Most EBV+ cells carried mutated Ig rearrangements, indicating that EBV resided mostly in memory or germinal center B cells. Ongoing somatic hypermutations were frequently observed, often resulting in mutations disrupting Ig gene expression. As, physiologically, B cells with such mutations undergo apoptosis, the surviving B cells with destructive mutations, which were also found to be present in EBV– cells, were named ‘forbidden B cells’ [7.Rudiger T. Weisenburger D.D. Anderson J.R. et al.Peripheral T-cell lymphoma (excluding anaplastic large-cell lymphoma): results from the Non-Hodgkin’s Lymphoma Classification Project.Ann Oncol. 2002; 13: 140-149Abstract Full Text Full Text PDF PubMed Scopus (371) Google Scholar, 8.Brauninger A. Spieker T. Willenbrock K. et al.Survival and clonal expansion of mutating ‘forbidden’ (immunoglobulin receptor-deficient) Epstein–Barr virus-infected B cells in angioimmunoblastic T cell lymphoma.J Exp Med. 2001; 194: 927-940Crossref PubMed Scopus (98) Google Scholar]. Hence, the group concluded that the microenvironment in AILD is likely to promote survival and clonal expansion of this new cell population.Definitions of neoplastic populations and prognostic factors in nodal T-cell lymphomas, based on our own experience and that of the Non-Hodgkin’s Lymphoma Classification Project, were described by Th. Rüdiger (Würzburg). Clonality was analyzed by studies of the TCR Vβ family using immunophenotyping and PCR. In AILD, survival was independent of mono- or polyclonality of T cells. However, in cases of high-grade AILD, defined by the presence of clear cell clusters or high numbers of large, atypical blasts, T-cell clonality was significantly higher than in low-grade disease. Confirming the results of others, and in agreement with the previous presentation, clonal populations were found significantly less frequently in AILD than in PTCL not otherwise specified (PTCL-NOS). In PTCL-NOS, survival was significantly associated with several risk factors, including grade, age, stage, performance status, lactate dehydrogenase (LDH) level and response to primary therapy, whereas in AILD, only younger age and remission in response to therapy were favorable prognostic factors [7.Rudiger T. Weisenburger D.D. Anderson J.R. et al.Peripheral T-cell lymphoma (excluding anaplastic large-cell lymphoma): results from the Non-Hodgkin’s Lymphoma Classification Project.Ann Oncol. 2002; 13: 140-149Abstract Full Text Full Text PDF PubMed Scopus (371) Google Scholar]. From the data presented, Rüdiger suggested that PTCL-NOS should be analyzed separately from AILD with regard to prognostic factors. Furthermore, he pointed out that analysis of clonality by TCR Vβ gene expression studies can be utilized to detect minimal residual disease and relapse.C. Sander (Munich) reviewed the current classification systems in cutaneous T-cell lymphomas (CTCL), which present as a heterogeneous group of PTCL showing variations in presentation, histology, immunophenotype and prognosis. At presentation, cutaneous lymphomas may be primary or may involve the skin as a secondary site of involvement. Their natural history is often more indolent than in nodal lymphomas and, for this reason, they often require different therapeutic approaches. A classification scheme should recognize those lymphomas that are unique to the skin, as well as those arising in other sites. In Sander’s opinion, an organ-specific classification system hinders the possibility of consensus among different medical specialties. For this reason he favors the comprehensive approach offered by the World Health Organization (WHO) classification of hematopoietic and lymphoid malignancies, which proposes that lymphomas should be viewed as a list of individual diseases, and that each disease can be defined by a constellation of morphological, biological and clinical features [9.Sander C.A. Flaig M.J. Jaffe E.S. Cutaneous manifestations of lymphoma: a clinical guide based on the WHO classification.World Health Organization. Clin Lymphoma. 2001; 2 (discussion 101–102): 86-100Scopus (39) Google Scholar].Cytogenetics and molecular geneticsThe session on cytogenetics and molecular genetics began with a review by M. Bentz (Ulm) of the history and technical development of currently available techniques. Furthermore, he introduced a genomic profiling technique in the form of a lymphoma oncogene chip, which he has developed in collaboration with P. Lichter (Heidelberg) [10.Wessendorf S. Fritz B. Wrobel G. et al.Automated screening for genomic imbalances using matrix-based comparative genomic hybridization.Lab Invest. 2002; 82: 47-60Crossref PubMed Scopus (77) Google Scholar]. This comprises probes from 645 clones, of which 372 cover potentially critical genomic regions (e.g. 12q13–12q15) and regions where tumor suppressor genes are located. All the methods described are being applied or are potentially applicable in PTCL. Questions that remain to be addressed include the significance of recurrent aberrations and their implications for prognosis. Furthermore, molecular mechanisms of pathogenesis may be more narrowly defined by analysis of genomic gains or losses using comparative genomic hybridization (CGH) and matrix-CGH. Bentz described, as an example, a model for the development of T-cell prolymphocytic leukemia (T-PLL): loss or biallelic mutations of the ataxia-telangiectasia mutated (ATM) gene—a frequent occurrence in T-PLL—may be involved in the initiation of the malignant process [11.Stilgenbauer S. Schaffner C. Litterst A. et al.Biallelic mutations in the ATM gene in T-prolymphocytic leukemia.Nat Med. 1997; 3: 1155-1159Crossref PubMed Scopus (205) Google Scholar]. A subsequent gain or activation of the T-cell lymphoma-1 (TCL-1) gene may lead to proliferation, and further modifications to the aggressive character of the disease.A review of the cytogenetic and molecular genetic events in PTCL, including our own results [presented by R. Siebert (Kiel)], shows that, with a few exceptions, only scarce and inconsistent data exist on chromosomal aberrations in subtypes of PTCL. As already reported by Bentz, in T-PLL the inv(14)(q11;q32)—or, less frequently, t(14;14)(q11;q32)—can lead to activation of TCL-1, and deletions in 11q22–11q23 affect the ATM gene [11.Stilgenbauer S. Schaffner C. Litterst A. et al.Biallelic mutations in the ATM gene in T-prolymphocytic leukemia.Nat Med. 1997; 3: 1155-1159Crossref PubMed Scopus (205) Google Scholar]. The role of other recurrent karyotypes in T-PLL, such as inv(8q)/t(8;8), del(13q14), del(12p13), del(6q) and dup(6p), is unknown [12.Soulier J. Pierron G. Vecchione D. et al.A complex pattern of recurrent chromosomal losses and gains in T-cell prolymphocytic leukemia.Genes Chromosomes Cancer. 2001; 31: 248-254Crossref PubMed Scopus (74) Google Scholar]. In hepatosplenic T-cell lymphoma, the characteristic aberrations are i(7q) and trisomy 8, but the functional consequencesof these changes have yet to be determined [13.Weidmann E. Hepatosplenic T cell lymphoma. A review on 45 cases since the first report describing the disease as a distinct lymphoma entity in 1990.Leukemia. 2000; 14: 991-997Crossref PubMed Scopus (208) Google Scholar]. Another well-characterized aberration is t(2;5)(p23;q35) in anaplastic large cell lymphoma (ALCL), which fuses the anaplastic lymphoma kinase (ALK) gene to nucleophosmin (NPM) [14.Ott G. Katzenberger T. Siebert R. et al.Chromosomal abnormalities in nodal and extranodal CD30+ anaplastic large cell lymphomas: infrequent detection of the t(2;5) in extranodal lymphomas.Genes Chromosomes Cancer. 1998; 22: 114-121Crossref PubMed Scopus (0) Google Scholar]. Recurrent cytogenetic findings in other PTCL are gains in chromosomes X, 1q, 3, 6p, 7/7q, 8/8q and 17q, and losses in X, 1p, 6q, 9p, 10q, 11q, 13q and 17p. A striking feature in certain PTCL, particularly in angioimmunoblastic lymphoma, is the presence of unrelated clones, a marker denoting the genomic instability that may contribute to the pathogenetic events in these cases.A. Zettl (Würzburg) presented data on the use of CGH in enteropathy-type T-cell lymphoma and PTCL-NOS. While chromosomal gains at chromosome 9q were found to characterize enteropathy-type T-cell lymphoma [15.Zettl A. Ott G. Makulik A. et al.Chromosomal gains at 9q characterize enteropathy-type T-cell lymphoma.Am J Pathol. 2002; 161: 1635-1645Abstract Full Text Full Text PDF PubMed Scopus (118) Google Scholar], gains and losses were more complex in 44 patients with PTCL-NOS. Frequent gains were found at chromosomes 7q (36%) and 9q (18%), and losses at chromosomes 6q (41%), 13q (39%), 5q (27%), 9p (27%), 10q (27%) and 12q (25%). As changes at chromosomes 6q, 13q, 9p and 7q have been described in other PTCL, and losses of 5q and 12q were found more exclusively in PTCL-NOS, Zettl concluded that these regions may represent areas encompassing genes responsible for the development or progression of PTCL-NOS. Some candidate genes from these loci are now being evaluated for functional properties.In conclusion, the aims of cytogenetics and molecular genetics analysis in PTCL should be to characterize subtypes and prognostic features, and also to clarify the basis of pathophysiological events.Treatment of primary cutaneous and disseminated T-cell lymphomasC. Sander (Munich) presented an overview on prognosis and current treatment approaches in primary cutaneous lymphomas. He emphasized the heterogeneity of these diseases, in terms of histology, immunophenotype and prognosis, and pointed out that primary cutaneous lymphomas are, in many instances, distinct from morphologically similar lymphomas arising in lymph nodes [16.Willemze R. Primary cutaneous lymphomas.Curr Opin Oncol. 2000; 12: 419-425Crossref PubMed Scopus (28) Google Scholar], and that their natural history is more commonly indolent. For example, in the case of cutaneous lymphoma with a favorable prognosis, such as mycosis fungoides, only 15% to 20% of patients die of lymphoma-related complications. Even patients with clinical stage IA may have a normal life expectancy. Patients with stages I–III mycosis fungoides respond to psoralen and ultraviolet A irradiation (PUVA), or to combinations of PUVA with retinoids or interferon. In contrast, the clinical course of Sézary syndrome is usually aggressive, with an estimated 5-year survival of 11%. A promising new treatment option in this disease is extracorporal photopheresis [17.Siegel R.S. Pandolfino T. Guitart J. et al.Primary cutaneous T-cell lymphoma: review and current concepts.J Clin Oncol. 2000; 18: 2908-2925Crossref PubMed Scopus (202) Google Scholar]. For patients with unspecified primary cutaneous lymphomas presenting as solitary lesions, and ALCL, Sander proposed local radiotherapy and, in cases with multiple lesions, multiagent chemotherapy. Owing to the poor prognosis in blastic NK-cell lymphoma, extranodal NK/T-cell lymphoma, nasal type lymphoma and T-lymphoblastic (LB) lymphoma with skin involvement, multiagent chemotherapy is generally required.J. Schetelig (Berlin) focused on the development of therapy for AILD, and current high-dose therapy options in this disease. He pointed out that the most difficult objective in AILD is the induction of lasting remissions. W. Siegert and co-workers [18.Siegert W. Agthe A. Griesser H. et al.Treatment of angioimmunoblastic lymphadenopathy (AILD)-type T-cell lymphoma using prednisone with or without the COPBLAM/IMVP-16 regimen. A multicenter study. Kiel Lymphoma Study Group.Ann Intern Med. 1992; 117: 364-370Crossref PubMed Scopus (106) Google Scholar] have demonstrated, in an initial clinical trial, that combination chemotherapy should be the treatment of choice. The complete response (CR) rates in this study, which compared a combination of cyclophosphamide, vincristine, prednisone, bleomycin, adriamycin, procarbacin, ifosfamide, methotrexate and VP-16 (COPBLAM/IMVP-16) versus prednisone, were 59% versus 28%. However, relapses within the first year were frequent. Similar results after chemotherapy were achieved in other studies. Retrospective data from the European Group for Blood and Marrow Transplantation (EBMT), from 29 patients receiving high-dose therapy followed by autologous stem-cell support, demonstrated an improved response rate of 20/29 CRs, compared with 13/29 CRs after conventional chemotherapy before high-dose therapy. Fourteen of the patients received transplants after first-line therapy, and 15 patients after second- or third-line therapy. The 5-year overall survival in this population, estimated from a Kaplan–Meier analysis, was >50%, and in patients who received primary high-dose therapy it was >70%. Schetelig concluded that high-dose therapy is feasible in AILD and should be the treatment standard in relapse, and that further studies are needed to confirm the beneficial outcome in the primarily high-dose-treated population.M. Reiser (Cologne) reported the retrospective results of a single-center study in 66 patients with T-cell lymphomas, accrued between 1992 and 1997 in Cologne, 28 of whom were diagnosed with PTCL-NOS, 19 with ALCL, 12 with LB T-cell lymphoma and seven with AILD. The overall response rate, following mainly anthracyclin-based regimens, was 76%, and the mean overall survival was 8.2 years. The mean survival differed significantly (log rank P = 0.0288) between the T-cell lymphoma subgroups: ALCL 11.1 years; LB 7.1 years; PTCL-NOS 6.6 years; and AILD 1.5 years. Differences in overall survival according to the International Prognostic Index (IPI) were also significant. Additional prognostically unfavorable factors were elevated LDH, B-symptoms and extranodal involvement, all of which showed significant between-subgroup differences in univariate analyses. In their evaluation, advanced stage and bone marrow involvement did not influence the prognosis [19.Reiser M. Josting A. Soltani M. et al.T-cell non-Hodgkin’s lymphoma in adults: clinicopathological characteristics, response to treatment and prognostic factors.Leuk Lymphoma. 2002; 43: 805-811Crossref PubMed Scopus (46) Google Scholar]. Reiser emphasized that in T-cell lymphomas, the histological subtype and risk factors may be more relevant for the estimation of prognosis than the T-cell phenotype alone.C. Gisselbrecht (Paris) described the development of treatment protocols for PTCL by the Groupe d’Etude des Lymphomes de l’Adulte (GELA). Early studies did not stratify treatment for T- and B-cell lymphomas. In both the LNH84 and the LNH87 trials, the T-cell phenotype was associated with a worse outcome compared with the B-cell phenotype [20.Gisselbrecht C. Gaulard P. Lepage E. et al.Prognostic significance of T-cell phenotype in aggressive non-Hodgkin’s lymphomas. Groupe d’Etudes des Lymphomes de l’Adulte (GELA).Blood. 1998; 92: 76-82PubMed Google Scholar, 21.Coiffier B. Brousse N. Peuchmaur M. et al.Peripheral T-cell lymphomas have a worse prognosis than B-cell lymphomas: a prospective study of 361 immunophenotyped patients treated with the LNH-84 regimen. The GELA (Groupe d’Etude des Lymphomes Agressives).Ann Oncol. 1990; 1: 45-50Abstract Full Text PDF PubMed Scopus (219) Google Scholar], with the exception of ALCL, which was found to have an even better prognosis than high-grade B-cell lymphomas. In the LNH87 study, the outcome of non-ALCL T-cell lymphomas was comparable to that of B-cell lymphomas in patients with an IPI of 0 and 1. Thus, worse results were due to an unfavorable IPI [21.Coiffier B. Brousse N. Peuchmaur M. et al.Peripheral T-cell lymphomas have a worse prognosis than B-cell lymphomas: a prospective study of 361 immunophenotyped patients treated with the LNH-84 regimen. The GELA (Groupe d’Etude des Lymphomes Agressives).Ann Oncol. 1990; 1: 45-50Abstract Full Text PDF PubMed Scopus (219) Google Scholar]. From their experience, the French group concluded that the induction of CR should be the primary aim in the treatment of T-cell lymphomas. A subgroup of the T-cell lymphoma patients achieving CR within the LNH87 trial was randomized to receive autologous stem cell transplantation versus conventional chemotherapy. In an intention-to-treat analysis, this study did not show differences in survival. Two ongoing trials of the LNH98 study generation are currently in progress: one in patients up to 60 years of age receiving sequential vincristine, prednisone, cyclophosphamide, doxorubicin and methotrexate (COPADM) with dexamethasone (Dexa), or cytarabine and etoposide (CYVE) with Dexa followed by maintenance therapy; and the second in patients >60 years of age receiving etoposide/methylprednisolone/high-dose cytarabine/cisplatin (ESHAP) plus retinoic acid. Preliminary analyses suggest that neither of these regimens improves the outcome of patients with PTCL. Gisselbrecht concluded that the current achievements in PTCL are unsatisfactory. In his opinion, phase II studies with well-defined evaluation criteria represent an adequate approach to the problem. Consequently, intensified standard regimens or high-dose therapy strategies should be further evaluated. Other treatment options to be explored are regimens that encompass standard and experimental procedures, including monoclonal antibodies or other experimental drugs.The Italian experience of therapy and prognosis of PTCL was presented by P. L. Zinzani (Bologna). First, he described several studies, advancing from single- to multicenter trials, establishing the role of gemcitabine in CTCL. After promising results in a small pilot study [22.Zinzani P.L. Magagnoli M. Bendandi M. et al.Therapy with gemcitabine in pretreated peripheral T-cell lymphoma patients.Ann Oncol. 1998; 9: 1351-1353Abstract Full Text PDF PubMed Scopus (110) Google Scholar], a phase II study with gemcitabine at a dose of 1200 mg/m2, administered on days 1, 8 and 15 of a 28-day schedule, was conducted. In 44 pretreated patients, an overall response rate of 71% (12% CR) was achieved [23.Zinzani P.L. Baliva G. Magagnoli M. et al.Gemcitabine treatment in pretreated cutaneous T-cell lymphoma: experience in 44 patients.J Clin Oncol. 2000; 18: 2603-2606Crossref PubMed Scopus (206) Google Scholar]. Recently, a multicenter study using gemcitabine in primary CTCL has been initiated by the Italian Cutaneous Lymphoma Study Group. Another focus of research, by the Intergruppo Italiano Linfomi (IIL), described by Zinzani, was the retrospective analysis of outcome and prognostic factors in 383 PTCL-NOS patients, most of whom were treated with anthracyclin-based regimens. The 5-year overall survival in this patient population was 44%. In a multivariate analysis, only age, performance status, LDH level and bone marrow infiltration were identified as prognostic indicators. The IIL is now initiating two studies in pretreated patients: one investigating temozolamide in cutaneous T-cell lymphomas and another examining a combination of cyclophosphamide/doxorubicin/vincristine/prednisolone (CHOP) and alemtuzumab (MabCamPath®) in PTCL-NOS.Antibody treatment of T-cell malignanciesM. Gramatzki (Erlangen) discussed the basic requirements for successful antibody therapy in PTCL. Some antibodies have failed to achieve therapeutic responses as a consequence of the remarkable variety of T-cell differentiation stages and antigen expression. For example, the IL-2 receptor CD25 or CD30 are expressed only on a limited number of T-cell tumors. Even the CD3 antibodies are not reactive in all PTCL, and are reactive in only some T-cell acute lymphoblastic leukemia (ALL) cases. In addition, their use in transplant medicine has suggested that even low doses are likely to be associated with severe side effects, although this may not be true for all T-cell lymphomas [24.Gramatzki M. Burger R. Strobel G. et al.Therapy with OKT3 monoclonal antibody in refractory T cell acute lymphoblastic leukemia induces interleukin-2 responsiveness.Leukemia. 1995; 9: 382-390PubMed Google Scholar]. Most PTCL and T-cell ALL express the CD7 antigen, with the notable exception of CTCL. The Erlangen group presented results from animal experiments and pilot clinical studies as well as data on a CD7-Pseudomonas exotoxin, suggesting that the CD7 antigen might be an interesting target [25.Baum W. Steininger H. Bair H.J. et al.Therapy with CD7 monoclonal antibody TH-69 is highly effective for xenografted human T-cell ALL.Br J Haematol. 1996; 95: 327-338Crossref PubMed Scopus (23) Google Scholar, 26.Peipp M. Kupers H. Saul D. et al.A recombinant CD7-specific single-chain immunotoxin is a potent inducer of apoptosis in acute leukemic T cells.Cancer Res. 2002; 62: 2848-2855PubMed Google Scholar]. The future of new antibody therapies for PTCL is dependent on further multicenter studies using these and other antigens, and the exploration of the mechanism of antibody-mediated cell killing. This should not only allow the optimal target antigen to be established, but also define the appropriate antibody isotype or immune construct.M. Dyer (Leicester) presented encouraging data from studies with alemtuzumab directed against the pan-lymphocyte antigen CD52 in the management of T-PLL. In this rare disease, the response to conventional chemotherapy is generally poor, with a median survival of only 6–8 months. Before alemtuzumab, the only drug demonstrated to achieve an improved survival was pentostatin [27.Mercieca J. Matutes E. Dearden C. et al.The role of pentostatin in the treatment of T-cell malignancies: analysis of response rate in 145 patients according to disease subtype.J Clin Oncol. 1994; 12: 2588-2593Crossref PubMed Scopus (172) Google Scholar]. After encouraging results obtained in a pilot study in T-PLL [28.Pawson R. Dyer M.J. Barge R. et al.Treatment of T-cell prolymphocytic leukemia with human CD52 antibody.J Clin Oncol. 1997; 15: 2667-2672Crossref PubMed Scopus (201) Google Scholar], Dyer and co-workers initiated an international study [29.Dearden C. Matutes E. Cazin B. et al.High remission rate in T-cell prolymphocytic leukemia with Campath-1H.Blood. 2001; 98: 1721-1726Crossref PubMed Scopus (266) Google Scholar] using alemtuzumab 30 mg, administered three times weekly, for up to 12 weeks. Mostly pretreated patients (n = 39), with a median age of 57 years, were enrolled, 24 of whom were chemoresistant. CR was achieved in 23 patients (59%) and partial response (PR) in six patients (15%). The best responses were observed in blood and bone marrow, followed by spleen, skin and lymph nodes. The median overall survival from the start of alemtuzumab treatment was 10 months, and 18 months in patients who had achieved a CR. The toxicity in this trial was acceptable and the response was better than with pentostatin; however, alemtuzumab was not found to be curative [29.Dearden C. Matutes E. Cazin B. et al.High remission rate in T-cell prolymphocytic leukemia with Campath-1H.Blood. 2001; 98: 1721-1726Crossref PubMed Scopus (266) Google Scholar]. Consequently, Dyer suggested that in T-PLL, alemtuzumab may allow patients to progress to autologous or allogeneic stem cell transplantation, and that transplantation should be considered early in first remission, in order to consolidate responses.Experiences with alemtuzumab in other T-cell malignancies were presented by R. Repp (Erlangen), who had previously participated in two Swedish trials, one in mycosis fungoides/Sézary syndrome (MF/SS) and one in advanced other PTCL. In the MF/SS trial, patients who required treatment, with documented failure to PUVA and a history of up to five previous systemic therapy regimens, were eligible. Twenty-two patients with stage II (three), stage III (10) and stage IV disease (nine) with MF/SS were included. Alemtuzumab 30 mg was administered three times weekly, for up to 12 weeks. An overall response of 55%, with 32% CR, was achieved. The median time to treatment failure was 12 months. Hematological toxicity was moderate. Non-hematological adverse events (mostly grade I and II) included fever, rigors, nausea, hypotension, rash, fatigue and bronchospasm. Four patients with

Only a few approaches are available to address the mechanisms of cell death in vivo which are induced by anticancer treatment in patients with malignancies. In this study in vitro chemosensitivity testing of primary peripheral blood leukemic cells of five patients suffering from different leukemic Non-Hodgkin's lymphomas (atypical CLL, typical CLL, Immunocytoma, Mantle Cell Lymphoma, Prolymphocytic Leukemia (PLL)) was combined with the analysis of the in vivo rate of apoptosis by flow-cytometry (Annexin V and depolarisation of mitochondrial membrane potential (MMP) by JC-1). Furthermore, changes in expression patterns of apoptosis related proteins during chemotherapeutic treatment were detected by Western Blot. Gene expression profiling (HG-U133A, Affymetrix, Santa Clara, CA) was employed to identify common marker genes of in vivo drug response. In vitro chemosensitivity was tested using the cytotoxic agents which the patients were scheduled to receive and was strongly correlated with effective reduction of leukemic lymphoma cells in patients resulting in complete remissions in all five cases. Due to the rapid clearance of apoptotic tumor cells in vivo neither the analysis of the in vivo rate of apoptosis and depolarisation of MMP nor the assessment of expression of regulators of apoptosis showed concordant results concerning the drug response. However, assessment of gene expression during therapy could identify a set of 30 genes to significant discriminate between samples from patients before treatment compared to samples from the same patients after receiving cytotoxic therapy. Among these 30 genes we found a high proportion of genes associated with apoptotic cell death and cell proliferation signalling including complement lysis inhibitor (clusterin, CLU, SP40), beta-catenin interacting protein (ICAT), peroxisome proliferator activated receptor alpha (PPARα), TNF alpha converting enzyme (ADAM 17 / TACE), homeo box A3 (HOXA), inositol polyphosphate 5 phophatase (PPI 5 PIV, SHIP1), FK 506 binding protein (FKBP 38) and inhibitor of p53 induced apoptosis alpha (NME 6). Clusterin is able to mediate apoptosis via p53 and increases drug-induced cell death when overexpressed as detected in our treated samples. The downregulation of NME 6 during chemotherapeutic treatment may enhance this effect. These results indicate that in vitro chemosensitivity testing and gene expression profiling can successfully be utilised to predict in vivo drug response in patients with leukemic NHL's and can be used to explore new pathway models of drug-induced cell death in vivo which are independent of different lymphoma subtypes and different treatment regimens.

In a variety of malignant cells Prostate-apoptosis-response-gene-4 (Par-4) exhibits a pro-apoptotic influence sensitizing these cells to apoptosis-inducing agents by downregulating expression of Bcl-2. Considering the crucial role of Bcl-2 in the development of chemoresistance of acute myeloid leukemia (AML) cells, we here assessed the potential of Par-4 to down-regulate Bcl-2 and to induce apoptosis in the erythroleukemic cell line HEL. Testing a potential pro-apoptotic role of Par-4 upon incubation with various conventional chemotherapeutic drugs, novel agents such as the signal transduction inhibitor STI 571 and the histone deacetylase (HDAC)- inhibitor trichostatin A (TSA), as well as with the experimental substances Fas and TRAIL, we provide evidence that in the erythroleukemic cell line HEL expression of Par-4 is not sufficient to sensitize to any of these pro-apoptotic stimuli. We further demonstrate that--in contrast to previous reports in non-AML cells--Par-4 expression in HEL cells leads to an upregulation of Bcl-2. Moreover, Par-4-positive HEL cells exhibit a decreased level of the proapoptotic protein Bax as compared to Par-4- negative cells. In addition, Par-4 increases the expression of Daxx--whose downregulation is associated with augmented chemosensitivity--as well as expression of the procaspases-8, -9 and -10, whereas the levels of the procaspases-3 and -7 remain unaltered. In conclusion we here demonstrate that in the erythroleukemic cell line HEL--in contrast to other cell types Par-4 fails to promote apoptosis and outline the underlying molecular mechanisms.