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Lothar Kanz

Publications and source records attributed to Lothar Kanz.

At least 37 records · Page 2Linked to original sources
PubMed2005

Telomere length and telomerase activity in the BCR-ABL-transformed murine Pro-B cell line BaF3 is unaffected by treatment with imatinib.

OBJECTIVE: Imatinib mesylate is a novel tyrosine kinase inhibitor used for the treatment of Philadelphia chromosome positive (Ph+) leukemia and other malignancies. In previous studies, we found significant telomere shortening in Ph+ cells from patients with chronic myeloid leukemia (CML). Interestingly, imatinib treatment was found to lead to a normalization of previously shortened telomere length in CML patients. Based on recent reports demonstrating that c-ABL phosphorylates hTERT and thereby inhibits hTERT activity, a direct effect of imatinib on hTERT activity leading to telomere elongation in BCR-ABL-positive cells has been proposed by others. Such an effect could be of potential importance for telomere maintenance in Ph+ cells by facilitating clonal selection and progression of the disease to blast crisis. METHODS: We investigated the impact of imatinib on telomere length and telomerase activity of the interleukin-3 (IL-3)-dependent murine pro-B cell line BaF3 and the BCR-ABL-positive, IL-3-independent transfectant BaF3p185 in vitro. RESULTS: When BaF3 and BaF3p185 cells were treated with imatinib (the latter being rescued with IL-3), no effect on either telomerase activity or telomere length was observed. These findings can be explained by the cytoplasmatic localization of BCR-ABL found in BaF3p185 as compared to the nuclear localization of telomerase (and c-ABL). CONCLUSION: As opposed to recent reports for c-ABL, we do not see evidence for a functional interaction between BCR-ABL and hTERT in this model system arguing against imatinib-mediated upregulation of hTERT as a crucial factor for clonal selection and disease progression of CML.

Animals↗
PubMed2005

Fludarabine may induce durable remission in patients with leptomeningeal involvement of chronic lymphocytic leukemia.

Leptomeningeal involvement (LI) is a rare complication in the course of B-cell chronic lymphocytic leukemia (CLL). It is difficult to assess, thus several cases may go unrecognized. Here we report on six patients with LI of B-CLL. Neurologic symptoms were present in five of six patients. Cerebral MRI, although performed in all subjects, was diagnostic in two patients only. Examination of cerebrospinal fluid by cytology and immunophenotyping revealed LI in all six cases. One patient received whole brain irradiation, two patients received intrathecal therapy or intravenous fludarabine respectively. Clinical responses occurred in one patient after irradiation and two patients after fludarabine. Response in CSF was observed in all four evaluable patients after intrathecal therapy (n=2) and fludarabine (n=2). Survival for the patient who received irradiation was five months and for the two patients treated with intrathecal therapy three and six months respectively. One of the patients on fludarabine treatment survived for 21 months with an 11 month event-free survival for the CNS manifestations while the other patient has been in an ongoing meningeal CR and hematologic PR for 20 months. We conclude that fludarabine may be useful in meningeal involvement of CLL with impact on systemic disease.

Adult↗
PubMed2005

Role of postchemotherapy surgery in the management of patients with liver metastases from germ cell tumors.

OBJECTIVE: To evaluate the role of postchemotherapy adjunctive surgery in patients with liver metastases from germ cell cancer (GCT). PATIENTS AND METHODS: Forty-three male patients with nonseminoma were treated in different multicenter treatment protocols between 1990 and 1999, and they underwent hepatic surgery. The results of postchemotherapy surgical resection, histologic findings found during postchemotherapy surgery, and prognostic factors for survival were assessed. RESULTS: Thirty-five of 43 patients (81%) were initially diagnosed with liver metastases and advanced GCT, and 8 patients (19%) presented with metachronous liver metastases after a median interval of 16 months (range, 6-103 months). Twelve patients (28%) had isolated liver metastases after completion of chemotherapy, while 31 patients (72%) had additional residual extrahepatic tumor masses. Liver surgery included tumor excision or segmentectomy in 32 patients (74%) and hepatectomy (right/left) or resection of multiple segments in 11 patients (26%). Histologic analysis of postchemotherapy resected residua yielded necrosis in 67%, teratoma in 12%, and viable cancer in 21%. Additional resections at other sites have been performed in 31 patients revealing necrosis in 61% (n = 19), teratoma in 29% (n = 9), and vital carcinoma in 10% (n = 3). In 39% of patients, histologic findings differed among liver and other resection sites. Refractoriness to chemotherapy was associated with a shorter survival after surgery, and a trend was seen in patients with elevation of AFP. CONCLUSION: The high rate of viable cancer and teratoma found in liver specimens, differing histologic results at residual tumor locations, and the high survival rate achieved support a multidisciplinary approach including resection of liver masses since no accurate selection of patients can narrow the use of surgery.

Adolescent↗
PubMed2005

The role of sphingosine 1-phosphate receptors in the trafficking of hematopoietic progenitor cells.

Sphingosine 1-phosphate (S1P) is an ubiquitously present extracellular lipid mediator that is released by several cell types, particularly by activated platelets. The effects of S1P are mediated by a specific family of G protein-coupled sphingosine 1-phosphate receptors (S1P1-S1P5). We demonstrate that S1P acts on hematopoietic progenitor cells as a chemotactic factor, attracting peripheral blood CD34(+) cells in vitro. Furthermore, constant activation of S1P receptors augments CXCR4-mediated signal transduction induced by stromal cell-derived factor 1 (SDF-1). These effects are most likely mediated by the S1P1 receptor consistently expressed in both primitive and committed CD34(+) hematopoietic progenitor cells (HPCs). In vivo, sustained activation of S1P1 by a receptor agonist during the homing process resulted in increased engraftment. Given the fact that activated platelets represent a major source of extracellular S1P, SDF-1-mediated stem cell homing may occur at sites of tissue injury in addition to the bone marrow. This could explain the previously observed contribution of primary hematopoietic stem cells to tissue repair in myocardial infarction and other diseases.

Animals↗
PubMed2005

Effect of tyrosine kinase inhibition using imatinib on normal lymphohematopoietic cells.

Imatinib is a selective tyrosine kinase inhibitor used for the treatment of Philadelphia chromosome-positive leukemias and other malignancies. An important clinical observation is that imatinib can affect the function of normal nonmalignant cells resulting in myelosuppression in treated patients. This observation is supported by the recent findings suggesting that imatinib might affect mobilization, proliferation, and differentiation of hematopoietic progenitor cells while leaving hematopoietic stem cells unaffected. Furthermore, the induction of a specific T cell response seems to be impaired in chronic myeloid leukemia (CML) patients treated with imatinib in contrast to patients receiving interferon-alpha. Recent studies demonstrate that in vitro exposure of mobilized human CD34(+) progenitors to imatinib inhibits their differentiation into dendritic cells. This is of importance as some of the therapeutic effects in the treatment of patients with CML are mediated by the induction of leukemia-specific T cell responses. Studies investigating the effects of imatinib on normal hematopoiesis are of interest because they might help us better understand the side effects observed clinically and might lead to the identification of novel therapeutic applications of the drug (e.g., in Bcr-Abl(-) myeloproliferative disorders and potentially as an immunomodulatory agent).

Antineoplastic Agents↗
PubMed2005

Mucormycoses in patients with hematologic malignancies: an emerging fungal infection.

BACKGROUND AND OBJECTIVES: Mucormycoses are seen with an increasing incidence in immunocompromised patients. Most common presentations are rhinocerebral and pulmonary. We here report the experience of a single center with mucormycoses in patients with hematologic malignancies. RESULTS: Mucormycoses were diagnosed in six patients, (median age of 52 years; range, 26-74) treated between 2001-2004. Diagnoses included acute myeloid leukemia (AML) (n=3), acute lymphoblastic leukemia (n=1), chronic lymphocytic leukemia (n=1) and multiple myeloma (n=1). Mucormycosis was diagnosed in the neutropenic state following allogeneic hematopoietic cell transplantation (n=3) or intense chemotherapy (n=3). Sites of infections were rhinocerebral, facial and pulmonary involvement in one patient each and disseminated mucormycosis in three patients. The diagnosis was established by computed tomography followed by surgical interventions and histological diagnosis in 4 patients and post-mortem in two patients. Species identified were Rhizopus (n=3), Rhizomucor (n=2) and Absidia (n=1). Treatment responses were best if surgical resection was followed by aggressive antifungal chemotherapy. Five of six 6 patients died, all of complications of mucormycosis or their underlying disease. Only one patient with facial mucormycosis is still alive. CONCLUSIONS: This experience demonstrates that patient with mucormycoses have a high mortality rate and early recognition followed by aggressive surgical debridement, high dose antifungal therapy and attempts to correct the underlying immunocompromised state are crucial in the treatment of this fatal infection.

Adult↗
PubMed2004

Myeloma cell contamination of peripheral blood stem-cell grafts can predict the outcome in multiple myeloma patients after high-dose chemotherapy and autologous stem-cell transplantation.

PURPOSE: High-dose chemotherapy with hematopoietic stem-cell rescue is increasingly being used in the treatment of multiple myeloma. Bone marrow and also peripheral blood stem-cell (PBSC) grafts contain measurable quantities of plasma cells, the biological significance of which is unknown. METHODS: Patients with multiple myeloma were mobilized with chemotherapy and filgrastim. The number of CD38++/CD138+ cells/kg in the grafts for autologous transplantation was determined by flow cytometry. Patients were stratified into two groups (threshold 4.5 x 10(5) plasma cells kg(-1)) of reinfused plasma cells in the first autologous graft. RESULTS: The median statistical progression-free survival was 14 months (4-34 months) in the high-contamination group (>4.5 x 10(5) plasma cells kg(-1)) compared to 26 months (4-43 months) in the low-contamination group (<4.5 x 10(5) plasma cells kg(-1), P =0.0096). Patients with 13q deletion were more frequently found to have a high contamination of the stem-cell graft with malignant plasma cells. CONCLUSIONS: Patients with graft contamination of more than 4.5 x 10(5) plasma cells kg(-1) had a high risk of early disease progression after high-dose chemotherapy. In vivo tumor cell purging prior to mobilization chemotherapy might be one strategy to improve the time to progression of high-risk patients.

Adult↗
PubMed2004

Fatal immune-mediated pancytopenia and a TRALI-like syndrome associated with high titers of recipient-type antibodies against donor-derived peripheral blood cells after allogeneic bone marrow transplantation following dose reduced conditioning.

Pancytopenia occurring after bone marrow transplantation is a rare complication. A 47 year old patient with progression of multiple myeloma after standard therapy received an allogeneic marrow graft from a matched unrelated donor. The non-myeloablative conditioning regimen consisted of fludarabine, cyclophosphamide, rabbit anti-thymocyte globulin and total body irradiation. GVHD prophylaxis consisted of cyclosporine. Neutrophil engraftment was as expected and the patient was discharged without signs of acute GvHD. On day +34 the patient presented with clinical and laboratory findings consistent with severe pancytopenia. Antibodies against red cells, platelets, lymphocytes and granulocytes were detected in extremely high titers. Immune-mediated pancytopenia was refractory on multiple immunosuppressive treatment strategies. Proliferation of polyclonal plasma cells of recipient-type that was documented postmortem, was most likely responsible for excessive antibody formation.

Anemia, Hemolytic, Autoimmune↗
PubMed2004

The sphingosine 1-phosphate receptor agonist FTY720 supports CXCR4-dependent migration and bone marrow homing of human CD34+ progenitor cells.

The novel immunosuppressant FTY720 activates sphingosine 1-phosphate receptors (S1PRs) that affect responsiveness of lymphocytes to chemokines such as stromal cell-derived factor 1 (SDF-1), resulting in increased lymphocyte homing to secondary lymphoid organs. Since SDF-1 and its receptor CXCR4 are also involved in bone marrow (BM) homing of hematopoietic stem and progenitor cells (HPCs), we analyzed expression of S1PRs and the influence of FTY720 on SDF-1/CXCR4-mediated effects in human HPCs. By reverse transcriptase-polymerase chain reaction (RT-PCR), S1PRs were expressed in mobilized CD34+ HPCs, particularly in primitive CD34+/CD38- cells. Incubation of HPCs with FTY720 resulted in prolonged SDF-1-induced calcium mobilization and actin polymerization, and substantially increased SDF-1-dependent in vitro transendothelial migration, without affecting VLA-4, VLA-5, and CXCR4 expression. In nonobese diabetic-severe combined immunodeficient (NOD/SCID) mice, the number of CD34+/CD38- cells that homed to the BM after 18 hours was significantly raised by pretreatment of animals and cells with FTY720, tending to result in improved engraftment. In addition, in vitro growth of HPCs (week-5 cobblestone area-forming cells [CAFCs]) was 2.4-fold increased. We conclude that activation of S1PRs by FTY720 increases CXCR4 function in HPCs both in vitro and in vivo, supporting homing and proliferation of HPCs. In the hematopoietic microenvironment, S1PRs are involved in migration and maintenance of HPCs by modulating the effects of SDF-1.

Antigens, CD↗
PubMed2004

Induction of adipophilin-specific cytotoxic T lymphocytes using a novel HLA-A2-binding peptide that mediates tumor cell lysis.

Identification of tumor-associated antigens and advances in tumor immunology resulted in the development of vaccination strategies to treat patients with malignant diseases. Using a novel approach that combines DNA chip analysis of tumor samples with isolation of peptides on the surface of tumor cells, a HLA-A*0201-binding peptide derived from the adipophilin protein was identified. Adipophilin is involved in lipid storage and was thought to be expressed only in adipocytes, but it can be found in other cell types such as macrophages or tumor cells. In the present study, we analyzed the possible use of this peptide as a T-cell epitope presented by malignant cells. To accomplish this, we induced CTL responses using this HLA-A*0201-binding peptide. The in vitro-induced CTLs efficiently lysed cells pulsed with the adipophilin peptide and HLA-matched tumor cell lines in an antigen-specific and HLA-restricted manner. Finally, the induced CTLs recognized autologous dendritic cells (DCs) pulsed with the antigenic peptide or transfected with tumor RNA purified from an adipophilin-expressing tumor cell line. To further analyze the possible use of this peptide in immunotherapies of human malignancies, we induced adipophilin-specific CTLs using peripheral blood mononuclear cells and DCs from HLA-A*0201-positive patients with chronic lymphatic leukemia and plasma cell leukemia. The in vitro-generated CTLs recognized autologous chronic lymphatic leukemia cells and malignant plasma cells, whereas they spared nonmalignant resting or activated B and T lymphocytes, monocytes, or DCs. Our results demonstrate that this peptide might represent an interesting candidate for the development of cancer vaccines designed to target adipophilin-derived epitopes in a wide range of malignancies.

Antigen Presentation↗
PubMed2004

Dendritic cells in vaccination therapies of human malignant disease.

Dendritic cells (DC) are the most efficient antigen presenting cells in various in vitro systems and DC are now introduced to early clinical use. Tumor antigen loaded DC might potentially add therapeutic benefit with dendritic cell based vaccination. This review will focus on dendritic cell biology relevant to investigators who work in transitional research programs and will discuss the rationale of DC source, antigen loading and route of vaccination. An overview of published and on-going clinical trials in human malignant diseases will be provided forming the basis for a discussion of perspectives of dendritic cell vaccination in various human malignancies.

Antigens, Neoplasm↗
PubMed2004

Intravascular lymphoma - a rare cause of hemolytic anemia and neurologic disorders.

Intravascular lymphoma is an uncommon and often overlooked form of non-Hodgkin's lymphoma characterized by extensive proliferation of lymphoid cells within the lumina of small and medium-sized vessels. Clinical symptoms of the disease are variable and often nonspecific, mostly neurologic in nature. With an aggressive course, intravascular lymphomatosis has a poor prognosis and is rarely diagnosed ante mortem. We describe here a 76-year-old woman with the clinical diagnoses of hemolytic anemia and progressive lethargy where intravascular lymphomatosis turned out as the underlying cause of the disease.

Aged↗
PubMed2004

Prospective multicenter phase II study of irinotecan as third-line therapy in metastatic colorectal cancer and progression after bolus and infusional 5-fluorouracil.

Irinotecan has proven anti-tumor activity as induction treatment in combination with 5-fluorouracil (5-FU) or as second-line treatment after 5-FU in patients with metastatic colorectal cancer. The aim of the present phase II study was to evaluate irinotecan as third-line chemotherapy in patients with colorectal cancer after sequential treatment with bolus 5-FU followed by an infusional 5-FU regimen. Patients pretreated with bolus 5-FU/folinic acid and the infusional 5-FU/folinic acid regimen were treated with 350 mg/m irinotecan i.v. once every 3 weeks in a multicenter phase II study. Tumor size was measured every cycle and treatment with irinotecan was continued until the occurrence of progressive disease or unacceptable toxicity. A total of 50 pretreated patients were included. Of the 45 evaluable patients, 13.3% [n=6, 95% confidence interval (CI) 5.1-26.8] attained a response (complete/partial response) to treatment lasting 5.6 months (95% CI 4.2-6.3) and in four patients response has been confirmed (8.9%, 95% CI 2.5-21.2). Disease stabilization was noted in 51.1% of the patients (n=23, 95% CI 35.8-66.3). The median duration of response/disease stabilization was 4.2 months (95% CI 3.2-6.0). Median overall survival was 7.9 months (95% CI 6.1-11.1), corresponding to a calculated 1-year survival of 28.3% (95% CI 15.2-41.3). Severe neutropenia occurred in 14% (n=7) and anemia grade III in 6% of the patients (n=3). The most frequent non-hematological toxicity grade III/IV related to treatment was diarrhea in 24% of the patients (n=12), followed by vomiting in 8% (n=4) and constipation as well as infection in two patients each (4%) (evaluable n=50). We conclude single-agent irinotecan is an effective and well-tolerable treatment in pretreated patients with metastatic colorectal cancer after failure of bolus and infusional 5-FU/folinic acid regimens. Elderly patients had the same probability to respond.

Adult↗
PubMed2004

Additional transplantation of ex vivo generated megakaryocytic cells after high-dose chemotherapy.

The additional transplantation of ex vivo generated hematopoietic (post)-progenitor cells represents a possible approach to ameliorate high-dose chemotherapy induced cytopenia. We investigated the feasibility of the large-scale expansion and transplantation of autologous megakaryocytic cells in four patients with advanced solid tumors. Up to 1,460x10(6) ex vivo generated cells were administered without adverse effects but no clear cut effect on platelet recovery was observed.

Antigens, CD34↗
PubMed2003

Prognostic value of minimal residual disease quantification by real-time reverse transcriptase polymerase chain reaction in patients with core binding factor leukemias.

PURPOSE: In patients with acute myeloblastic leukemia with t(8;21) or inv(16) aberrations (core binding factor [CBF] leukemias), minimal residual disease (MRD) can be sensitively detected during and after chemotherapy by use of molecular methods. However, the prognostic impact of qualitative MRD detection is still under debate. In this study, the prognostic value of MRD quantification in patients with CBF leukemias was assessed. PATIENTS AND METHODS: We quantified MRD at various time points during and after therapy by real-time reverse transcriptase polymerase chain reaction (RT-PCR) for AML1/MTG8 and CBFB/MYH11 in 37 patients with CBF leukemias treated within a multicenter trial. RESULTS: At initial diagnosis, the patients showed a heterogenous fusion gene expression relative to glyceraldehyde 3-phosphate dehydrogenase with a variation of more than two log steps. According to MRD status during/after therapy, two groups of patients were separated. Of the 26 patients who had MRD levels of less than 1% in relation to initial diagnosis at all time points tested after induction chemotherapy, only two experienced relapse after a median follow-up of 19 months. Of the 11 patients who had a sample with an MRD level >/= 1% at least at one time point after induction therapy, 10 experienced relapse, with a median remission duration of 10 months (P <.001). The median interval between the informative MRD sample and clinical relapse in these patients was 3 months. CONCLUSION: MRD quantification by real-time RT-PCR allows the identification of patients with a high risk of relapse among the CBF leukemias.

Adolescent↗
PubMed2003

Imatinib mesylate affects the development and function of dendritic cells generated from CD34+ peripheral blood progenitor cells.

Imatinib mesylate (STI571) is a competitive Bcr-Abl tyrosine kinase inhibitor and has yielded encouraging results in treatment of chronic myelogenous leukemia (CML) and gastrointestinal stroma tumors (GISTs). Apart from inhibition of the Abl protein tyrosine kinases, it also shows activity against platelet-derived growth factor receptor (PDGF-R), c-Kit, Abl-related gene (ARG), and their fusion proteins while sparing other kinases. In vitro studies have revealed that imatinib mesylate can inhibit growth of cell lines and primitive malignant progenitor cells in CML expressing Bcr-Abl. However, little is known about the effects of imatinib mesylate on nonmalignant hematopoietic cells. In the current study we demonstrate that in vitro exposure of mobilized human CD34+ progenitors to therapeutic concentrations of imatinib mesylate (1-5 microM) inhibits their differentiation into dendritic cells (DCs). DCs obtained after 10 to 16 days of culture in the presence of imatinib mesylate showed concentration-dependent reduced expression levels of CD1a and costimulatory molecules such as CD80 and CD40. Furthermore, exposure to imatinib mesylate inhibited the induction of primary cytotoxic T-lymphocyte (CTL) responses. The inhibitory effects of imatinib mesylate were accompanied by down-regulation of nuclear localized RelB protein. Our results demonstrate that imatinib mesylate can act on normal hematopoietic cells and inhibits the differentiation and function of DCs, which is in part mediated via the nuclear factor kappaB signal transduction pathway.

Antigens, CD↗