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Andreas Neubauer

Publications and source records attributed to Andreas Neubauer.

At least 19 recordsLinked to original sources
PubMed2006

Interferon regulatory factor-8 is indispensable for the expression of promyelocytic leukemia and the formation of nuclear bodies in myeloid cells.

Interferon (IFN) regulatory factor-8 (IRF-8), previously known as ICSBP, is a myeloid cell essential transcription factor. Mice with null mutation in IRF-8 are defective in the ability of myeloid progenitor cells to mature toward macrophage lineage. Accordingly, these mice develop chronic myelogenous leukemia (CML). We demonstrate here that IRF-8 is an obligatory regulator of the promyelocytic leukemia (PML) gene in activated macrophages, leading to the expression of the PML-I isoform. This regulation is most effective together with two other transcription factors, IRF-1 and PU.1. PML is a tumor suppressor gene that serves as a scaffold protein for nuclear bodies. IRF-8 is not only essential for the IFN-gamma-induced expression of PML in activated macrophages but also for the formation of nuclear bodies. Reduced IRF-8 transcript levels were reported in CML patients, and a recovery to normal levels was observed in patients in remission following treatment with IFN-alpha. We demonstrate a significant correlation between the levels of IRF-8 and PML in these CML patients. Together, our results indicate that some of the myeloleukemia suppressor activities of IRF-8 are mediated through the regulation of PML. When IRF-8 levels are compromised, the reduced PML expression may lead to genome instability and eventually to the leukemic phenotype.

Animals↗
PubMed2006

Adaptive secretion of granulocyte-macrophage colony-stimulating factor (GM-CSF) mediates imatinib and nilotinib resistance in BCR/ABL+ progenitors via JAK-2/STAT-5 pathway activation.

Overcoming imatinib mesylate (IM) resistance and disease persistence in patients with chronic myeloid leukemia (CML) is of considerable importance to the issue of potential cure. Here we asked whether autocrine signaling contributes to survival of BCR/ABL+ cells in the presence of IM and nilotinib (NI; AMN107), a novel, more selective Abl inhibitor. Conditioned media (CM) of IM-resistant LAMA84 cell clones (R-CM) was found to substantially protect IM-naive LAMA cells and primary CML progenitors from IM- or NI-induced cell death. This was due to an increased secretion of the granulocyte-macrophage colony-stimulating factor (GM-CSF), which was identified as the causative factor mediating IM resistance in R-CM. GM-CSF elicited IM and NI drug resistance via a BCR/ABL-independent activation of the janus kinases 2 (JAK-2)/signal transducer and activator of transcription 5 (STAT-5) signaling pathway in GM-CSF receptor alpha receptor (CD116)-expressing cells, including primary CD34+/CD116+ GM progenitors (GMPs). Elevated mRNA and protein levels of GM-CSF were detected in IM-resistant patient samples, suggesting a contribution of GM-CSF secretion for IM and NI resistance in vivo. Importantly, inhibition of JAK-2 with AG490 abrogated GM-CSF-mediated STAT-5 phosphorylation and NI resistance in vitro. Together, adaptive autocrine secretion of GM-CSF mediates BCR/ABL-independent IM and NI resistance via activation of the antiapoptotic JAK-2/STAT-5 pathway. Inhibition of JAK-2 overcomes GM-CSF-induced IM and NI progenitor cell resistance, providing a rationale for the application of JAK-2 inhibitors to eradicate residual disease in CML.

Benzamides↗
PubMed2006

Randomized trial of single compared with tandem high-dose chemotherapy followed by autologous stem-cell transplantation in patients with chemotherapy-sensitive metastatic breast cancer.

PURPOSE: To compare progression-free survival between single and tandem high-dose chemotherapy (HDT) followed by autologous stem-cell transplantation in chemotherapy-sensitive metastatic breast cancer patients. PATIENTS AND METHODS: Between February 1997 and June 2001, 187 patients with complete and partial remission were randomly assigned to receive either one or two cycles of HDT, consisting of thiotepa (125 mg/m2/d for 4 days), cyclophosphamide (1,500 mg/m2/d for 4 days), and carboplatin (200 mg/m2/d for 4 days), followed by autologous stem-cell transplantation. RESULTS: One hundred seventy one of 187 randomly assigned patients completed first HDT, but only 52 of 85 completed the second HDT cycle in the tandem HDT arm. The rate of complete remission on an intent-to-treat-basis was 33% in the single-dose HDT arm and 37% in the tandem HDT arm (P = .48). The median progression-free survival times in single and tandem HDT arms were 9.4 and 11.2 months, respectively (one-sided P = .06; two one-sided P = .12), whereas median overall survival time tended to be greater after single versus tandem HDT (29 v 23.5 months, respectively; P = .4). In a multivariate analysis for progression-free survival, tandem HDT (hazard ratio [HR] = 0.71; 95% CI, 0.52 to 0.98; P = .03) and achievement of complete remission after induction chemotherapy (HR = 0.59; 95% CI, 0.37 to 0.96; P = .03) were factors for a better progression-free survival, whereas the factor of three or more sites of metastases (HR = 1.66; 95% CI, 1.12 to 2.47; P = .01) was associated with a worse progression-free survival. CONCLUSION: Despite a trend of improved progression-free survival, tandem HDT cannot be recommended for patients with chemotherapy-sensitive metastatic breast cancer because of a trend for shorter overall survival and higher toxicity compared with single HDT.

Adult↗
PubMed2006

Treatment of HNSCC cell lines with the EGFR-specific inhibitor cetuximab (Erbitux) results in paradox phosphorylation of tyrosine 1173 in the receptor.

Overexpression of the epidermal growth factor receptor (EGFR, ErbB1, HER1) is frequent in head and neck squamous cell carcinomas (HNSCCs) and correlates with disease progression. Inhibition of EGFR with the kinase inhibitor AG1478 abolished receptor phosphorylation and reduced cell proliferation. However, treatment of HNSCC cells with cetuximab (Erbitux), a monoclonal antibody designed to block the EGFR ligand binding site, led to paradox EGFR activation due to hyperphosphorylation of tyrosine 1173, however, with a concomitant reduction in Erk1/2 phosphorylation levels. No pronounced influence on cell proliferation levels could be observed after treatment with this antibody. Since cetuximab appears able to activate EGFR in HNSCC cell lines, it is necessary to rethink the exact mechanisms by which cetuximab that recently was approved for the treatment of advanced head and neck cancer, inhibits tumor growth.

Antibodies, Monoclonal↗
PubMed2006

Discordant results of flow cytometric ZAP-70 expression status in B-CLL samples if different gating strategies are applied.

BACKGROUND: Recent studies have identified ZAP-70 expression status as an excellent prognostic parameter in chronic lymphocytic leukemia (CLL). ZAP-70 expression can be determined by direct antibody staining followed by flow cytometric analysis. However, there are currently several different gating strategies for analysis. We compared those strategies for ZAP-70 expression analysis. METHODS: One hundred and one patients with B-CLL were analyzed employing a directly labeled alexa-fluor-488-ZAP-70-antibody. In 27 cases, we additionally measured and analyzed ZAP-70 expression, together with healthy controls as described previously. RESULTS: Applying either T-/NK-cell isotype or healthy control analysis strategies on patient samples that were processed in parallel revealed discrepant results in 48% (12/25) of all cases. Taken together with the 74 B-CLL patients, who were analyzed with regard to average reference values, disconcordant results were obtained in 58% of the samples. We demonstrate that high variances in ZAP-70 T-/NK-cell staining within B-CLL patients, paired with a close proximity of ZAP-70 B-cell values to the suggested cut-off levels, may lead to interpretation difficulties of ZAP-70 status. CONCLUSIONS: We conclude that different gating strategies for determining flow cytometric ZAP-70 expression status produce highly discordant results. Further standardization is required before ZAP-70 can be used as a reliable prognostic parameter in immunophenotyping of B-CLL.

Adult↗
PubMed2006

Clonality analyses in gastric MALT (mucosa-associated lymphoid tissue).

B-cell clonality, assessed by PCR for amplification of the VDJ region of the immunoglobulin heavy chain gene (IgH), is used to support the diagnosis of gastric mucosa-associated lymphoid tissue (MALT) lymphoma (GML). It has also been described in simple gastritis cases, without any histological hint for lymphoma, especially in the presence of lymphoid follicles. We analyzed a randomly selected series of 130 gastric biopsies with histologically described lymphoid follicle formation and investigated these for the prevalence of B-cell clonality using different PCR-based methods to discuss its usefulness in the differential diagnosis of GML. A seminested PCR for the IgH gene was performed and evaluated by agarose gel electrophoresis, GeneScan technique, and melting-curve analysis. The majority of cases revealed histologically chronic active Helicobacter pylori gastritis. Monoclonality was detected in 7.5% (10 of 130) and 7% (9 of 130) of samples using GeneScan technique and melting-curve analysis, respectively. In eight of eight samples investigated, monoclonality was not demonstrated in deeper sections of the same biopsy using GeneScan technique, favoring the diagnosis of a reactive process rather than overt lymphoma. Electrophoresis proved more difficult to interpret and revealed clonal cases in 14% (18 of 130). We conclude that GeneScan technique and melting curve analysis are the methods of choice for clonality analysis in gastric biopsies. Analyses of different deep sections with advanced PCR technology might be the method of choice for future analyses. In our opinion, the question of whether detected monoclonality can be interpreted as malignant lymphoma is still open.

B-Lymphocytes↗
PubMed2006

Dexamethasone, high-dose cytarabine, and cisplatin in combination with rituximab as salvage treatment for patients with relapsed or refractory aggressive non-Hodgkin's lymphoma.

We designed a multicenter Phase II trial to prospectively evaluate the efficacy and safety of the combination of rituximab with the DHAP regimen (dexamethasone, high-dose cytarabine, cisplatin) in patients who relapsed after or were resistant to a CHOP-like regimen. A total of 53 patients with relapsed or resistant aggressive B-cell NHL were analyzed. The overall response rate was 62.3 percent. With a median follow-up of 24.9 months, median overall and progression-free survivals were 8.5 and 6.7 months, respectively. Immunochemotherapy with rituximab and DHAP proved to be feasible and effective in this patient population.

Adult↗
PubMed2006

Helicobacter pylori eradication in gastric mucosa-associated lymphoid tissue lymphoma: Results of a 196-patient series.

Prospective studies have reported ongoing remissions in most patients with localized Helicobacter pylori-positive gastric mucosa-associated lymphoid tissue lymphoma after curing the infection. Using specific selection criteria, the outcome of 196 patients treated in routine clinical practice was analysed. Complete remission rates, stability of remissions and frequency of relapse and histologic residual disease were in accordance with previous prospective clinical trials, whereas the median age was higher. Only a minority had a complete staging, and it may be expected that there is a significant group of patients with an unrecognized higher stage in this cohort. The frequency of follow-up investigations was also not considered as recommended in a considerable number of patients. Nevertheless, the outcome of patients was favourable regardless of limited staging and follow-up procedures. Amended recommendations and special guidelines for elderly and patients with concomitant disease should be considered.

Adult↗
PubMed2005

Clinical trial of valproic acid and all-trans retinoic acid in patients with poor-risk acute myeloid leukemia.

BACKGROUND: Valproic acid (VPA), a histone deacetylase (HDAC) inhibitor, induced in vitro differentiation of primary acute myeloid leukemia (AML) blasts, an effect enhanced by all-trans retinoic acid (ATRA). Clinical responses to VPA were recently observed in patients with myelodysplastic syndrome (MDS). Herein, the authors have described results of a clinical trial with VPA plus ATRA in 26 patients with poor-risk AML. METHODS: VPA (5-10 mg/kg starting dose) and ATRA (45 mg/m(2)) were administered orally. Low-dose AraC or hydroxyurea were permitted to control leukocytosis. Biologic activity of VPA was confirmed by serial analysis of HDAC2 protein levels in peripheral blood (PB) mononuclear cells. RESULTS: Nineteen of 26 patients completed at least 4 weeks of VPA/ATRA treatment; 7 patients were withdrawn prematurely because of rapidly progressive disease (n = 3) or unacceptable neurologic and cardiovascular toxicity (n = 4). Additional cytoreductive treatment was required in 58% of patients enrolled. Median treatment duration was 3 months. No patient achieved complete remission, one with de novo AML had a minor response, and two patients with secondary AML arising from myeloproliferative disorder (MPD) achieved a partial remission and clearance of PB blasts, respectively. The latter responses were accompanied by profound granulocytosis and erythrocytosis in both patients, reminiscent of the response pattern known from ATRA treatment of acute promyelocytic leukemia. However, cytogenetic analysis of isolated CD34(+) cells and granulocytes did not reveal terminal differentiation of leukemic blasts. CONCLUSIONS: Treatment with VPA/ATRA results in transient disease control in a subset of patients with AML that has evolved from a myeloproliferative disorder but not in patients with a primary or MDS-related AML.

Administration, Oral↗
PubMed2005

Down-regulation of interferon regulatory factor 4 gene expression in leukemic cells due to hypermethylation of CpG motifs in the promoter region.

Although the bcr-abl translocation has been shown to be the causative genetic aberration in chronic myeloid leukemia (CML), there is mounting evidence that the deregulation of other genes, such as the transcription factor interferon regulatory factor 4 (IRF-4), is also implicated in the pathogenesis of CML. Promoter methylation of CpG target sites or direct deletions/insertions of genes are mechanisms of a reversible or permanent silencing of gene expression, respectively. Therefore, we investigated whether IRF-4 promoter methylation or mutation may be involved in the regulation of IRF-4 expression in leukemia cells. Whereas promoter mutations or structural rearrangements could be excluded as a cause of altered IRF-4 expression in hematopoietic cells, the IRF-4 promoter methylation status was found to significantly influence IRF-4 transcription. First, treatment of IRF-4-negative lymphoid, myeloid and monocytic cell lines with the methylation-inhibitor 5-aza-2-deoxycytidine resulted in a time- and concentration-dependent increase of IRF-4 mRNA and protein levels. Second, using a restriction-PCR-assay and bisulfite-sequencing we identified specifically methylated CpG sites in IRF-4-negative but not in IRF-4-positive cells. Third, we clearly determined promoter methylation as a mechanism for IRF-4 down-regulation via reporter gene assays, but did not detect an association of methylational status and mRNA expression of DNA methyltransferases or methyl-CpG-binding proteins. Together, these data suggest CpG site-specific IRF-4 promoter methylation as a putative mechanism of down-regulated IRF-4 expression in leukemia.

Cell Line, Tumor↗
PubMed2005

FLT3-ITD-, but not BCR/ABL-transformed cells require concurrent Akt/mTor blockage to undergo apoptosis after histone deacetylase inhibitor treatment.

Leukemias are differentially sensitive to histone deacytelase inhibitor (HDI)-induced apoptosis, but molecular reasons for this remain unclear. We here show that BCR/ABL-, but not FMS-like tyrosine kinase 3 (FLT3)-internal tandem duplication (ITD)-transformed 32D cells or primary acute myeloid leukemia (AML) blasts undergo apoptosis after treatment with the HDI valproic acid (VPA) plus all-trans retinoic acid (VPA/ATRA). A particular VPA/ATRA responsiveness of Philadelphia chromosome-positive (Ph+) acute lymphatic leukemia (ALL) was confirmed in a therapy-refractory patient in vivo. HDI-stimulated apoptosis in Ph+ cells was caspase dependent, but independent from Akt pathway inhibition. Conversely, separate blockage of the Akt/mTor-signaling pathway was a prerequisite for overcoming apoptosis resistance to VPA/ATRA in FLT3-ITD cells, and primary AML blasts (n = 9). In conclusion, constitutive Akt activation causes apoptosis resistance to VPA/ATRA in AML, but not in Ph+ leukemia. This warrants the application of HDI-based therapies in poor-risk Ph+ ALL, and the use of Akt/mTor inhibitors to overcome HDI resistance in AML.

Antineoplastic Agents↗
PubMed2005

Long-term follow-up of gastric MALT lymphoma after Helicobacter pylori eradication.

PURPOSE: Cure of infection induces remissions in most patients with early stage Helicobacter pylori- (Hp) positive gastric MALT (mucosa-associated lymphoid tissue) lymphoma (GML). We tracked the long-term stability of remissions in this prospective, multicenter trial. PATIENTS AND METHODS: In 120 patients with stage I(1E) disease, we performed sequential endoscopic-bioptic follow-up after Hp eradication and polymerase chain reaction of the rearranged immunoglobulin heavy chain gene. The status of t(11;18) was assessed in 65 patients. RESULTS: Median follow-up was 75 months (range, one to 116). Five-year survival was 90%. Eighty percent of patients (96 of 120) achieved complete histologic remission (CR). Eighty percent of CRs are in continuous complete histologic remission (CCR). Three percent of CR patients (three of 96) relapsed and were referred for alternative treatment. Seventeen percent of CR patients (16 of 96) showed histologic residual disease (RD) during follow-up; a watch-and-wait strategy was applied, and all entered into a second CR. After a median follow-up of 63 months, 14 of 52 analyzed patients reaching CR showed ongoing B-cell monoclonality. Fifteen percent of GMLs were t(11;18) positive. Both t(11;18) and ongoing monoclonality were associated with a significantly higher risk for no response or relapse (P =.004, P =.007), but also present in patients in CCR. Early gastric cancer was diagnosed in three cases during follow-up. CONCLUSION: Cure of Hp infection results in CCR in most patients. Histologic RD, B-cell monoclonality, and t(11;18) were present in a considerable number of CR patients. A watch-and-wait strategy is justified when close follow-up is guaranteed.

Adult↗
PubMed2005

Mesenchymal stem cells obtained after bone marrow transplantation or peripheral blood stem cell transplantation originate from host tissue.

Mesenchymal stem cells (MSC) obtained from human bone marrow have been described as adult stem cells with the ability of extensive self-renewal and clonal expansion, as well as the capacity to differentiate into various tissue types and to modulate the immune system. Some data indicate that leukapheresis products may also contain non-hematopoietic stem cells, as they occur in whole bone marrow transplantation (BMT). However, there is still controversy whether MSC expand in the host after transplantation like blood progenitor cells do. Therefore, we were interested in finding out if graft MSC can be detected in leukapheresis products and in bone marrow after BMT and peripheral blood stem cell transplantation (PBSCT). Every sample from total bone marrow transplants exhibited growth of MSC after in vitro culture, but not one of nine leukapheresis products did. In addition, bone marrow aspirates of 9 patients receiving BMT and of 18 patients after PBSCT were examined for origin of MSC. Almost all MSC samples exhibited a complete host profile, whereas peripheral blood cells were of donor origin. We conclude that even if trace amounts of MSC are co-transplanted during PBSCT or BMT, they do not expand significantly in the host bone marrow.

Antigens, CD↗
PubMed2005

Conditioning with 8-Gy total body irradiation and fludarabine for allogeneic hematopoietic stem cell transplantation in acute myeloid leukemia.

Seventy-one patients with acute myeloid leukemia (AML), most of them (63/71) considered ineligible for conventional allogeneic hematopoietic stem cell transplantation (HSCT), were enrolled into a phase 2 study on reduced-intensity myeloablative conditioning with fractionated 8-Gy total body irradiation (TBI) and fludarabine (120 mg/m2). Patients received mobilized peripheral blood stem cells (n = 68) or bone marrow (n = 3) from siblings (n = 39) or unrelated donors (n = 32). Thirty-six patients received a transplant in complete remission (CR) and 35 had untreated or refractory disease (non-CR). Median patient age was 51 years (range, 20-66 years). Sustained engraftment was attained in all evaluable patients. With a median follow-up of 25.9 months (range, 3.7-61.2 months) in surviving patients, probabilities of overall survival for patients who received a transplant in CR and non-CR were 81% and 21% at 2 years, respectively. Relapse-free survival rates were 78% and 16%. The cumulative incidence of nonrelapse mortality (NRM) in CR patients was 8% at 2 years and beyond but amounted to 37% at 2 years in non-CR patients. Outcome data in this poor-risk population indicate that allogeneic HSCT from related or unrelated donors with 8-Gy TBI/fludarabine conditioning is feasible with low NRM and preserved antileukemic activity in AML patients in first or later CR.

Adult↗
PubMed2005

Activation of the RAS pathway is predictive for a chemosensitive phenotype of acute myelogenous leukemia blasts.

PURPOSE: Activation of the RAS pathway plays a major role in cancer cells. In acute myeloid leukemia (AML), mutations of the RAS genes cause an intrinsic activation of this pathway. Until now, clinical studies could not find clear association of RAS mutations with the clinical outcome after AML therapy. This could be due to alternative initiating events for activation of the RAS pathway like constitutive tyrosine kinase activation or mutations in Ras-regulating genes. EXPERIMENTAL DESIGN: In total, 191 AML patients (126 as training population and 65 as test population) were studied for Ras activity with a glutathione S-transferase pull-down assay using Raf binding of activated Ras. RESULTS: AML samples showed a wide range of Ras activity values, which was in contrast to normal bone marrow donors who showed no or very limited Ras activity. Using a Ras binding score based on semiquantitative Western blotting, we defined patients with strong Ras activity and compared Ras activity with RAS mutation. Surprisingly, only a minority of RAS mutated AML samples (22.2%) showed strong Ras activity, whereas 25 patients presented strong Ras activity in the absence of RAS mutations. Clinical outcome did not show differences according to RAS mutations. In contrast, Ras activity predicted for a high response rate (P <0.05) and proved to be an independent factor for overall survival rate (P <0.05) in younger AML patients receiving high-dose 1-beta-D-arabinofuranosylcytosine as induction therapy. CONCLUSION: The data highlight the role for alternative pathways of Ras activation without RAS mutations. Intrinsically activated Ras seems to increase sensitivity of the AML blast to high-dose 1-beta-D-arabinofuranosylcytosine therapy.

Antimetabolites, Antineoplastic↗
PubMed2005

Immunochemotherapy with rituximab and cyclophosphamide, doxorubicin, vincristine, and prednisone significantly improves response and time to treatment failure, but not long-term outcome in patients with previously untreated mantle cell lymphoma: results of a prospective randomized trial of the German Low Grade Lymphoma Study Group (GLSG).

PURPOSE: Mantle cell lymphoma (MCL) is characterized by a poor prognosis with a low to moderate sensitivity to chemotherapy and a median survival of only 3 to 4 years. In an attempt to improve outcome, the German Low Grade Lymphoma Study Group (GLSG) initiated a randomized trial comparing the combination of cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) and rituximab (R-CHOP) with CHOP alone as first-line therapy for advanced-stage MCL. PATIENTS AND METHODS: One hundred twenty-two previously untreated patients with advanced-stage MCL were randomly assigned to six cycles of CHOP (n = 60) or R-CHOP (n = 62). Patients up to 65 years of age achieving a partial or complete remission underwent a second randomization to either myeloablative radiochemotherapy followed by autologous stem-cell transplantation or interferon alfa maintenance (IFNalpha). All patients older than 65 years received IFNalpha maintenance. RESULTS: R-CHOP was significantly superior to CHOP in terms of overall response rate (94% v 75%; P = .0054), complete remission rate (34% v 7%; P = .00024), and time to treatment failure (TTF; median, 21 v 14 months; P = .0131). No differences were observed for progression-free survival. Toxicity was acceptable, with no major differences between the two therapeutic groups. CONCLUSION: The combined immunochemotherapy with R-CHOP resulted in a significantly higher response rate and a prolongation of the TTF as compared with chemotherapy alone. Hence, R-CHOP may serve as a new baseline regimen for advanced stage MCL, but needs to be further improved by novel strategies in remission.

Aged↗