ALK-positive histiocytosis: a new clinicopathologic spectrum highlighting neurologic involvement and responses to ALK inhibition.

ALK-positive histiocytosis is a rare subtype of histiocytic neoplasm first described in 2008 in 3 infants with multisystemic disease involving the liver and hematopoietic system. This entity has subsequently been documented in case reports and series to occupy a wider clinicopathologic spectrum with recurrent KIF5B-ALK fusions. The full clinicopathologic and molecular spectra of ALK-positive histiocytosis remain, however, poorly characterized. Here, we describe the largest study of ALK-positive histiocytosis to date, with detailed clinicopathologic data of 39 cases, including 37 cases with confirmed ALK rearrangements. The clinical spectrum comprised distinct clinical phenotypic groups: infants with multisystemic disease with liver and hematopoietic involvement, as originally described (Group 1A: 6/39), other patients with multisystemic disease (Group 1B: 10/39), and patients with single-system disease (Group 2: 23/39). Nineteen patients of the entire cohort (49%) had neurologic involvement (7 and 12 from Groups 1B and 2, respectively). Histology included classic xanthogranuloma features in almost one-third of cases, whereas the majority displayed a more densely cellular, monomorphic appearance without lipidized histiocytes but sometimes more spindled or epithelioid morphology. Neoplastic histiocytes were positive for macrophage markers and often conferred strong expression of phosphorylated extracellular signal-regulated kinase, confirming MAPK pathway activation. KIF5B-ALK fusions were detected in 27 patients, whereas CLTC-ALK, TPM3-ALK, TFG-ALK, EML4-ALK, and DCTN1-ALK fusions were identified in single cases. Robust and durable responses were observed in 11/11 patients treated with ALK inhibition, 10 with neurologic involvement. This study presents the existing clinicopathologic and molecular landscape of ALK-positive histiocytosis and provides guidance for the clinical management of this emerging histiocytic entity.

Imatinib dose reduction in major molecular response of chronic myeloid leukemia: results from the German Chronic Myeloid Leukemia-Study IV.

Standard first-line therapy of chronic myeloid leukemia is treatment with imatinib. In the randomized German Chronic Myeloid Leukemia-Study IV, more potent BCR-ABL inhibition with 800 mg ('high-dose') imatinib accelerated achievement of a deep molecular remission. However, whether and when a de-escalation of the dose intensity under high-dose imatinib can be safely performed without increasing the risk of losing deep molecular response is unknown. To gain insights into this clinically relevant question, we analyzed the outcome of imatinib dose reductions from 800 mg to 400 mg daily in the Chronic Myeloid Leukemia-Study IV. Of the 422 patients that were randomized to the 800 mg arm, 68 reduced imatinib to 400 mg after they had achieved at least a stable major molecular response. Of these 68 patients, 61 (90%) maintained major molecular remission on imatinib at 400 mg. Five of the seven patients who lost major molecular remission on the imatinib standard dose regained major molecular remission while still on 400 mg imatinib. Only two of 68 patients had to switch to more potent kinase inhibition to regain major molecular remission. Importantly, the lengths of the intervals between imatinib high-dose treatment before and after achieving major molecular remission were associated with the probabilities of maintaining major molecular remission with the standard dose of imatinib. Taken together, the data support the view that a deep molecular remission achieved with high-dose imatinib can be safely maintained with standard dose in most patients. Study protocol registered at clinicaltrials.gov 00055874.

Allogeneic hematopoietic cell transplantation in patients with myelofibrosis: A single center experience.

Myelofibrosis (MF) is a rare disease responsible for an increasing ineffective hematopoesis by a progressive fibrosing process in the bone marrow. The only curative treatment option is allogeneic hematopoietic cell transplantation (HCT). In this single-center analysis, we evaluated retrospectively 54 consecutive patients suffering from primary or secondary MF which underwent HCT from 1997 to 2014 after either myeloablative (MAC, n = 19) or reduced-intensity conditioning (RIC, n = 35). Overall survival (OS) and disease-free survival (DFS) after 3 years was 54/53 % for RIC versus 63/58 % for MAC (p = 0.8/0.97). Cumulative incidence of relapse was 34 % after RIC and 8 % after MAC (p = 0.16). Three-year non-relapse mortality (NRM) was 15 % after RIC and 34 % after MAC (p = 0.29). We found that RIC was associated with a lower incidence of acute graft versus host disease (GvHD; II-IV 26 vs. 0 %, p = 0.004). Evaluation of prognostic relevance of the Dynamic International Prognostic Scoring System (DIPSS) score showed a significant better OS in patient with risk score ≤3 versus >3 (after 3 years, 71 vs. 39 %, p = 0.008). While similar OS and DFS were observed with MAC or RIC, the use of RIC resulted in lower incidence of acute GvHD. RIC regimens may be therefore the preferred conditioning approach for allogeneic HCT in patients with MF.

Successful use of eculizumab for treatment of an acute hemolytic reaction after ABO-incompatible red blood cell transfusion.

BACKGROUND: Transfusion of ABO major-incompatible red blood cells (RBCs) can activate the complement system and can cause severe and even lethal acute hemolytic reactions. The activation of the complement system with formation of C3a and C5a (anaphylatoxins) and the release of hemoglobin from the lysed RBCs are thought to mediate clinical signs like fever, hypotension, pain, and acute renal failure. Therapeutic inhibition of the complement cascade in case of ABO-incompatible RBC transfusion would be desirable to ameliorate the signs and symptoms and to improve the outcome of the reaction. STUDY DESIGN AND METHODS: A patient with blood group B was erroneously transfused with a unit of group A2 RBCs. Within 1 hour after transfusion she received eculizumab, a monoclonal antibody that binds to the complement component C5 and blocks its cleavage. Clinical and immunohematologic observations are reported here. RESULTS: Hemoglobinemia and hemoglobinuria were present for several hours after transfusion, but she developed no hypotension, no renal failure, and no disseminated intravascular coagulation. As shown by flow cytometry, group A cells survived in the peripheral blood for more than 75 days. No immunoglobulin G was detectable by column agglutination technique on these cells. CONCLUSION: A low isoagglutinin titer and blood group A2 of the erroneously transfused cells most likely were the reason for the absence of clinical signs during and immediately after the ABO-incompatible transfusion. In the further course, eculizumab successfully protected the incompatible RBCs from hemolysis for several weeks.

High-dose chemotherapy and autologous haematopoietic stem-cell transplantation in older, fit patients with primary diffuse large B-cell CNS lymphoma (MARTA): a single-arm, phase 2 trial.

BACKGROUND: Available treatments for older patients with primary diffuse large B-cell CNS lymphoma (PCNSL) offer progression-free survival of up to 16 months. We aimed to investigate an intensified treatment of high-dose chemotherapy and autologous haematopoietic stem-cell transplantation (HSCT) in older patients with PCNSL. METHODS: MARTA was a prospective, single-arm, phase 2 study done at 15 research hospitals in Germany. Patients aged 65 years or older with newly diagnosed, untreated PCNSL were enrolled if they had an Eastern Cooperative Oncology Group performance status of 0-2 and were fit for high-dose chemotherapy and autologous HSCT. Induction treatment consisted of two 21-day cycles of high-dose intravenous methotrexate 3·5 g/m2 (day 1), intravenous cytarabine 2 g/m2 twice daily (days 2 and 3), and intravenous rituximab 375 mg/m2 (days 0 and 4) followed by high-dose chemotherapy with intravenous rituximab 375 mg/m2 (day -8), intravenous busulfan 3·2 mg/kg (days -7 and -6), and intravenous thiotepa 5 mg/kg (days -5 and -4) plus autologous HSCT. The primary endpoint was progression-free survival at 12 months in all patients who met eligibility criteria and started treatment. The study was registered with the German clinical trial registry, DRKS00011932, and recruitment is complete. FINDINGS: Between Nov 28, 2017, and Sept 16, 2020, 54 patients started induction treatment and 51 were included in the full analysis set. Median age was 71 years (IQR 68-75); 27 (53%) patients were female and 24 (47%) were male. At a median follow-up of 23·0 months (IQR 16·8-37·4), 23 (45%) of 51 patients progressed, relapsed, or died. 12-month progression-free survival was 58·8% (80% CI 48·9-68·2; 95% CI 44·1-70·9). During induction treatment, the most common grade 3-5 toxicities were thrombocytopenia and leukopenia (each in 52 [96%] of 54 patients). During high-dose chemotherapy and autologous HSCT, the most common grade 3-5 toxicity was leukopenia (37 [100%] of 37 patients). Treatment-related deaths were reported in three (6%) of 54 patients, all due to infectious complications. INTERPRETATION: Although the primary efficacy threshold was not met, short induction followed by high-dose chemotherapy and autologous HSCT is active in selected older patients with PCNSL and could serve as a benchmark for comparative trials. FUNDING: Else Kröner-Fresenius Foundation, Riemser Pharma, and Medical Center-University of Freiburg.

A prospective observational study of real-world treatment and outcome in secondary CNS lymphoma.

BACKGROUND: Secondary central nervous system lymphoma (SCNSL) confers a dismal prognosis and treatment advances are constrained by the lack of prospective studies and real-world treatment evidence. METHODS: Patients with SCNSL of all entities were included at first diagnosis and patient characteristics, treatment data, and outcomes were prospectively collected in the Secondary CNS Lymphoma Registry (SCNSL-R) (NCT05114330). FINDINGS: 279 patients from 47 institutions were enrolled from 2011 to 2022 and 243 patients (median age: 66 years; range: 23-86) were available for analysis. Of those, 49 (20 %) patients presented with synchronous (cohort I) and 194 (80 %) with metachronous SCNSL (cohort II). The predominant histology was diffuse large B-cell lymphoma (DLBCL, 68 %). Median overall survival (OS) from diagnosis of CNS involvement was 17·2 months (95 % CI 12-27·5), with longer OS in cohort I (60·6 months, 95 % CI 45·5-not estimable (NE)) than cohort II (11·4 months, 95 % CI 7·8-17·7, log-rank test p < 0.0001). Predominant induction regimens included R-CHOP/high-dose MTX (cohort I) and high-dose MTX/cytarabine (cohort II). Rituximab was used in 166 (68 %) of B-cell lymphoma. Undergoing consolidating high-dose therapy and autologous hematopoietic stem cell transplantation (HDT-ASCT) in partial response (PR) or better was associated with longer OS (HR adjusted 0·47 (95 % CI 0·25-0·89), p = 0·0197). INTERPRETATION: This study is the largest prospective cohort of SCNSL patients providing a comprehensive overview of an international real-world treatment landscape and outcomes. Prognosis was better in patients with SCNSL involvement at initial diagnosis (cohort I) and consolidating HDT-ASCT was associated with favorable outcome in patients with PR or better.

Phase II study of central nervous system (CNS)-directed chemotherapy including high-dose chemotherapy with autologous stem cell transplantation for CNS relapse of aggressive lymphomas.

The prognosis of patients with central nervous system relapse of aggressive lymphoma is very poor with no therapy established so far. In a prospective multicenter phase II study, we evaluated a potentially curative chemotherapy-only regimen in these patients. Adult immunocompetent patients 65 years of age or under received induction chemotherapy with MTX/IFO/DEP (methotrexate 4 g/m(2) intravenously (i.v.) Day 1, ifosfamide 2 g/m(2) i.v. Days 3- 5 and liposomal cytarabine 50 mg intrathecally (i.th) Day 6) and AraC/TT/DEP (cytarabine 3g/m(2) i.v. Days 1-2, thiotepa 40 mg/m(2) i.v. Day 2 and i.th. liposomal cytarabine 50 mg i.th. Day 3) followed by high-dose chemotherapy with carmustine 400 mg/m(2) i.v. Day -5, thiotepa 2×5 mg/kg i.v. Days -4 to -3 and etoposide 150 mg/m(2) i.v. Days -5 to -3, and autologous stem cell transplantation Day 0 (HD-ASCT). Thirty eligible patients (median age 58 years) were enrolled. After HD-ASCT (n=24), there was a complete remission in 15 (63%), partial remission in 2 (8%) and progressive disease in 7 (29%) patients. Myelotoxicity was the most adverse event with CTC grade 3/4 infections in 12% of MTX/IFO/DEP courses, 21% of AraC/TT/DEP courses and 46% of HD-ASCT courses. The 2-year time to treatment failure was 49%±19 for all patients and 58%±22 for patients completing HD-ASCT. The protocol assessed proved feasible and highly active with long-lasting remissions in a large proportion of patients. (ClinicalTrials.govIdentifier NCT01148173).

Patient Reported and Clinical Outcomes after High-Dose Chemotherapy and Autologous Stem Cell Transplantation in Primary Central Nervous System Lymphoma.

Primary central nervous system lymphomas (PCNSL) are rare and associated with an adverse prognosis. High-dose chemotherapy followed by autologous stem cell transplantation (HDC/ASCT) improves progression free (PFS) and overall survival (OS) but neurocognition, performance status and quality of life (QoL) in patient-reported outcome (PRO) after HDC/ASCT remains underexplored. Especially elderly patients may insufficiently recover from this demanding therapy. Therefore, this single-center analysis investigated all PCNSL patients who received HDC/ASCT at the University Hospital Tübingen from 2006-2021 (n = 40, median age 60.5 years) in a retrospective manner. The 2-year PFS/OS was 78.7%/77.3%, respectively, without significant differences between the tested age-groups (≤60 vs. >60 years, p = 0.531/p = 0.334). Higher Thiotepa dosage was an independent predictor for better OS (p = 0.018). Additionally, a one-time prospective, cross-sectional analysis after HDC/ASCT in the same cohort was performed (n = 31; median follow-up 45 months). Here, the median ECOG improved by HDC/ASCT from 1 to 0 and mini-mental state examinations revealed unimpaired neurocognitive functioning (median 28 pts.). PRO data collected by EORTC QLQ-C30 showed a good QoL in both age groups with an average global health status (GHS) of 68.82% (≤60y: 64.72%, >60y: 74.14%). Together, our data indicate that HDC/ASCT is an effective therapy with respect to disease control, overall health status and quality of life, irrespective of patient age.

The CysLT1 ligand leukotriene D4 supports alpha4beta1- and alpha5beta1-mediated adhesion and proliferation of CD34+ hematopoietic progenitor cells.

Cytokines and chemokines control hematopoietic stem and progenitor cell (HPC) proliferation and trafficking. However, the role of nonpeptide mediators in the bone marrow microenvironment has remained elusive. Particularly CysLT(1), a G protein-coupled receptor recognizing inflammatory mediators of the cysteinyl leukotriene family, is highly expressed in HPCs. We therefore analyzed the effects of its ligands on human CD34(+) HPCs. The most potent CysLT(1) ligand, LTD(4), rapidly and significantly up-regulated alpha(4)beta(1) and alpha(5)beta(1) integrin-dependent adhesion of both primitive and committed HPC. LTD(4)-triggered adhesion was inhibited by specific CysLT(1) antagonists. The effects of other CysLT(1) ligands were weak (LTC(4)) or absent (LTE(4)). In serum-free liquid cultures supplemented with various hematopoietic cytokines including IL-3, only LTD(4) significantly augmented the expansion of HPCs in a dose-dependent manner comparable to that of peptide growth factors. LTC(4) and LTE(4) were less effective. In CD34(+) cell lines and primary HPCs, LTD(4) induced phosphorylation of p44/42 ERK/MAPK and focal adhesion kinase-related tyrosine kinase Pyk2, which is linked to integrin activation. Bone marrow stromal cells produced biologically significant amounts of cysteinyl leukotrienes only when hematopoietic cells were absent, suggesting a regulatory feedback mechanism in the hematopoietic microenvironment. In contrast to antagonists of the homing-related G protein-coupled receptor CXCR4, administration of a CysLT(1) antagonist failed to induce human CD34(+) HPC mobilization in vivo. Our results suggest that cysteinyl leukotriene may contribute to HPC retention and proliferation only when cysteinyl leukotriene levels are increased either systemically during inflammation or locally during marrow aplasia.

Regulation of FLT3 and its ligand in normal hematopoietic progenitor cells.

FLT3 and its ligand (FL) are one of the regulators of normal hematopoiesis. Ligand-independent activation of FLT3 occurs in about 30% of acute myeloid leukemia cases and is one goal for selectively targeted therapies. However, the function of FLT3/FL in the regulation of non-malignant immature hematopoietic cells is poorly characterized. In order to elucidate the role of FLT3 in normal hematopoiesis, human adult CD34(+) hematopoietic progenitor cells were cultured in cytokine-supplemented liquid culture in the presence or absence of FLT3 inhibition by CEP-701 (lestaurtinib). Total cell number, lineage-committed, and primitive progenitors and apoptosis were assayed. FLT3 expression and FL secretion in various conditions were analyzed by fluorescent activated cell sorter and enzyme-linked immunosorbent assay. Effects of nonspecific targeting of FLT3 were evaluated with addition of imatinib (Gleevec) to cell cultures. It is demonstrated that FLT3 inhibition impaired cell and progenitor cell growth and increased the rate in apoptosis. Effects were observed independent of addition of FL. The dose-dependent growth inhibition was partially equalized by inhibiting FL with a neutralizing antibody. FLT3 inhibition resulted in markedly increased production of FL by cultured CD34(+) cells as well as upregulation of FLT3 expression. Imatinib mimicked effects of selective FLT3 inhibition. In conclusion, FLT3 and its ligand regulate proliferation of hematopoietic progenitor cells in an autocrine/paracrine manner Nonspecific inhibition of FLT3 may contribute to hematotoxicity caused by imatinib treatment.

VEGF-dependent induction of CD62E on endothelial cells mediates glioma tropism of adult haematopoietic progenitor cells.

Haematopoietic progenitor cells (HPC) are attracted by experimental gliomas in vivo. This attraction is further enhanced by irradiation or hypoxic preconditioning of the glioma cells. Adhesive interactions might be critical to the preferential accumulation of HPC within the glioma tissue. Here, we studied the interactions of HPC with endothelial cells. Exposure of human cerebral endothelial cells (SV-HCEC), human microvascular endothelial cells (HMEC) and brain tumour endothelial cells derived from human glioblastomas (BTEC) to supernatants of glioma cells and primary glioma cells (SN-G) induced the expression of E-selectin (CD62E). CD62E expression was further enhanced when the glioma cells had been exposed to irradiation or hypoxia prior to the collection of supernatants, as well as by irradiation or exposure to hypoxia of the endothelial cells. Vascular cell adhesion molecule 1 (VCAM-1) was constitutively expressed on SV-HCEC, HMEC and BTEC, but was not modulated by SN-G, irradiation or hypoxia. Transendothelial HPC migration was enhanced after CD62E induction in vitro. Neutralizing antibodies to CD62E strongly reduced the homing of lin(-)Sca-1(+)c-kit(+) cells to orthotopic SMA-560 gliomas in vivo. Tissue microarray sampling normal brain tissue and astrocytomas of WHO grades II-IV revealed a selective expression of CD62E on endothelial cells of tumour vessels. SN-G-induced CD62E expression on endothelial cells in vitro required transforming growth factor (TGF)-beta signalling in glioma cells and vascular endothelial growth factor (VEGF)/VEGF receptor 2 (VEGF-R2) signalling in endothelial cells. Further, we observed a nuclear factor kappa B-dependent activation of the CD62E promoter peaking at 12 h after VEGF-R2 activation by glioma-derived VEGF. Taken together, we identify glioma cell-induced CD62E expression on endothelial cells as one mediator of the glioma tropism of HPC.

Modulation of CXC chemokine receptor expression and function in human neutrophils during aging in vitro suggests a role in their clearance from circulation.

In mice, differential regulation of CXC chemokine receptor expression in circulating polymorphonuclear neutrophils (PMNs) undergoing senescence results in homing to the bone marrow. However, the role of this compartment and of the chemokine receptor CXCR4 is still under discussion, and only scarce data exist about CXCR4 function in human PMN. In our study, we provide evidence that also in human neutrophils, expression (cell surface and mRNA), chemotactic and signaling functions of the homing-related chemokine receptor CXCR4 are upregulated during aging in vitro, independent of addition of stimulatory cytokines (TNF, IL-1, IL-8, G-CSF). In contrast, interleukin-8 receptors are downmodulated (CXCR2) or remain unchanged (CXCR1), suggesting that human PMNs undergoing senescence acquire a phenotype that impairs inflammatory extravasation and favors homing to the bone marrow or other tissues involved in sequestration. Partially retained responsiveness to interleukin-8 may be important for neutrophil function when senescence occurs after extravasation in inflamed tissues.

Phase I Study of Oncolytic Vaccinia Virus GL-ONC1 in Patients with Peritoneal Carcinomatosis.

Purpose: Peritoneal carcinomatosis is common in advanced tumor stages or disease recurrence arising from gastrointestinal cancers, gynecologic malignancies, or primary peritoneal carcinoma. Because current therapies are mostly ineffective, new therapeutic approaches are needed. Here, we report on a phase I study designed to assess safety, MTD, and antitumor activity of intraperitoneal administration of oncolytic vaccinia virus GL-ONC1 in advanced stage peritoneal carcinomatosis patients.Patients and Methods: GL-ONC1 was administered intraperitoneally every 4 weeks for up to four cycles at three different dose levels (107-109 pfu) following a standard 3+3 dose escalation design. GL-ONC1 was infused via an indwelling catheter that enabled repetitive analyses of peritoneal fluid biopsies. The primary study objective was safety of GL-ONC1 according to Common Terminology Criteria for Adverse Events, version 4.0 (CTCAEv4.0).Results: Patients with advanced-stage peritoneal carcinomatosis (n = 7) or advanced peritoneal mesothelioma (n = 2) received 24 doses of GL-ONC1. Adverse events were limited to grades 1-3, including transient flu-like symptoms and increased abdominal pain, resulting from treatment-induced peritonitis. No DLT was reported, and the MTD was not reached. Furthermore, no signs of viral shedding were observed. Importantly, in 8 of 9 study patients, effective intraperitoneal infections, in-patient replication of GL-ONC1, and subsequent oncolysis were demonstrated in cycle 1. All patients developed neutralizing activities against GL-ONC1.Conclusions: GL-ONC1 was well tolerated when administered into the peritoneal cavity of patients with advanced stage peritoneal carcinomatosis. Efficient tumor cell infection, in-patient virus replication, and oncolysis were limited to treatment cycle 1 (ClinicalTrials.gov number, NCT01443260). Clin Cancer Res; 24(18); 4388-98. ©2018 AACR.

Hematopoietic growth factors for hematopoietic stem cell mobilization and expansion.

During inflammation and cytopenia, increased levels of hematopoietic growth factors (HPGFs) induce mobilization and proliferation of hematopoietic stem cells and hematopoietic progenitor cells (HPCs), resulting in spatial and quantitative in vivo expansion of the hematopoietic tissue. Exogenous administration of recombinant HPGFs, particularly granulocyte colony-stimulating factor (G-CSF), is routine for mobilization of stem cells, followed by collection and transplantation of autologous or allogeneic stem cells. In this review, we summarize experience using different HPGFs and HPGF combinations for stem cell mobilization, such as G-CSF, granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3), stem cell factor (SCF), and others. Preclinical and clinical studies of so-called early- and late-acting HPGFs for ex vivo expansion of HPCs are discussed, also with respect to the unresolved question whether expansion of repopulating stem cells can be achieved in vitro.

Differential effects of G protein coupled receptors on hematopoietic progenitor cell growth depend on their signaling capacities.

We have shown that CD34(+) hematopoietic progenitor and stem cells (HPCs) consistently express several G protein-coupled receptors (GPCRs): the chemokine receptor CXCR4, the cysteinyl-leukotriene receptor cysLT1, and receptors for sphingosine 1-phosphate (S1P), particularly S1P1. These GPCRs differentially mediate chemotactic, adhesive, and proliferative responses in HPCs. To elucidate the diversity of the responses observed, we compared their signaling capacities in CD34(+) cells. In primary CD34(+) progenitors, the strongest effects on calcium signaling (intracellular calcium fluxes) were mediated by cysLT1. Analyses in CD34(+) cell lines revealed that calcium signaling induced by cysLT1 was only partially inhibited by pertussis toxin (PTX), while responses induced by CXCR4 and S1P receptors were completely blocked. These findings indicate that cysLT1 signals via Gi and Gq proteins, while CXCR4 and also S1P receptors (e.g., S1P1) only induce Gi protein-mediated effects. By analysis of downstream signaling, we could provide further evidence that combined activation of PTX-insensitive (Gq-mediated) and PTX-sensitive (Gi-mediated) pathways by cysLT1 may explain the strong and broad effects of cysteinyl-leukotrienes in early hematopoietic cells, while signaling of CXCR4 and S1P1 solely depends on Gi proteins, resulting in effects mainly restricted to migration and adhesion.

Effect of FLT3 inhibition on normal hematopoietic progenitor cells.

Ligand-mediated activation of the FMS-like tyrosine kinase-3 (FLT3) receptor is important for normal proliferation of primitive hematopoietic cells. FLT3 expression in the bone marrow is restricted to CD34(+) cells and a subset of dendritic precursors. FLT3, as a member of the type III RTK subfamily, is closely related to c-kit, c-FMS, and PDGFalpha/beta and is an unspecific target of tyrosine kinase inhibitors, such as imatinib. Activating mutations of FLT3 play an important role in leukemogenesis and their presence is associated with poor prognosis in acute myeloid leukemia (AML). Targeting the mutation by inhibiting the tyrosine kinase activity of FLT3 is a promising therapeutic option in the treatment of AML patients. CEP-701 (Lestaurtinib), an indocarbazole derivate, is an FLT3 tyrosine kinase inhibitor. In this study, we investigated the effect of FLT3 kinase inhibition on normal hematopoietic stem and progenitor cells in vitro. FLT3 inhibition in normal CD34(+) cells resulted in a dose-dependent inhibitory effect in cell expansion. In contrast, progenitor cell function remained nearly unaffected. Blocking the FLT3 ligand by a neutralizing antibody partially restored the effects of FLT3 inhibition. These findings might explain hematotoxicity of tyrosine kinase inhibitors such as imatinib.

Thyrotropin serum concentrations in healthy volunteers are associated with depression-related personality traits.

BACKGROUND: Alterations of the hypothalamic-pituitary-thyroid system at the hypophyseal level have been described in affective disorders. The NEO Five-Factor Inventory is a widely used instrument, which assesses neuroticism, a strong marker for vulnerability to depression. METHODS: Endogenous serum concentrations of thyroid-stimulating hormone (TSH), free T3 and free T4 were measured and the NEO Five-Factor Inventory was performed in 121 healthy unrelated volunteers (51 male, 70 female; median age: 23 years, range from 17 to 71). RESULTS: The TSH serum concentrations showed a median of 1.35 mU/l with a range from 0.1 to 4.0. The free T3 serum concentrations were 5.2 +/- 0.7 pmol/l (mean +/- SD), and the free T4 concentrations 16.5 +/- 2.4 pmol/l (mean +/- SD). The power of 0.4 of the TSH serum concentration and the logarithm of the depression-related factor neuroticism had a bivariate normal distribution and were negatively correlated (r = -0.337, p = 0.0002). CONCLUSION: Low TSH levels in healthy humans might be linked to an increased risk to develop depression.

Irradiation and hypoxia promote homing of haematopoietic progenitor cells towards gliomas by TGF-beta-dependent HIF-1alpha-mediated induction of CXCL12.

Previously we defined a pathway of transforming growth factor beta (TGF-beta) and stromal cell-derived factor-1/CXC chemokine ligand 12 (SDF-1alpha/CXCL12) dependent migration of adult haematopoietic stem and progenitor cells (HPC) towards glioma cells in vitro and their homing to experimental gliomas in vivo. Hypoxia is a critical aspect of the microenvironment of gliomas and irradiation is an essential part of the standard therapy. To evaluate the therapeutic potential of HPC as vectors for a cell-based therapy of gliomas, we investigated the impact of hypoxia and irradiation on the attraction of HPC by glioma cells. Temozolomide (TMZ) treatment and hyperthermia served as controls. Supernatants of irradiated or hypoxic LNT-229 glioma cells promote HPC migration in vitro. Reporter assays reveal that the CXCL12 promoter activity is enhanced in LNT-229 cells at 24 h after irradiation at 8 Gy or after exposure to 1% oxygen for 12 h. The irradiation- and hypoxia-induced release of CXCL12 depends on hypoxia inducible factor-1 alpha (HIF-1alpha), but not on p53. Induction of transcriptional activity of HIF-1alpha by hypoxia or irradiation requires an intact TGF-beta signalling cascade. This delineates a novel stress signalling cascade in glioma cells involving TGF-beta, HIF-1alpha and CXCL12. Stress stimuli can be irradiation, hypoxia or TMZ, but not hyperthermia. Cerebral irradiation of nude mice at 21 days after intracerebral implantation of LNT-229 glioma induces tumour satellite formation and enhances the glioma tropism of HPC to the tumour bulk and even to these satellites in vivo. These data suggest that the use of HPC as cellular vectors in the treatment of glioblastoma may well be combined with irradiation or other anti-angiogenic therapies that induce tumour hypoxia.

Lessons from the bone marrow: how malignant glioma cells attract adult haematopoietic progenitor cells.

Stem and progenitor cells (PCs) of various lineages have become attractive vehicles to improve therapeutic gene delivery to cancers, notably glioblastoma. Here we report that adult human and murine haematopoietic PCs display a tropism for intracerebral gliomas but not for normal brain tissue in mice. Organotypic hippocampal slice culture and spheroid confrontation assays confirm a directed PC migration towards glioma cells ex vivo and in vitro. RNA interference-mediated disruption of transforming growth factor beta (TGF-beta) synthesis by the glioma cells strongly inhibits PC migration. We delineate a CXC chemokine ligand (CXCL) 12-dependent pathway of TGF-beta-induced PC migration that is facilitated by MMP-9-mediated stem cell factor cleavage in vitro. Moreover, neutralizing antibodies to CXCL12 strongly reduce PC homing to experimental gliomas in vivo. Thus, we define here the molecular mechanism underlying the glioma tropism of the probably most easily accessible PC population suitable for cancer therapy, that is, adult haematopoietic PC.

Prognostic relevance of HER2/neu in acute lymphoblastic leukemia and induction of NK cell reactivity against primary ALL blasts by trastuzumab.

The epidermal growth factor receptor HER2/neu is expressed on various cancers and represents a negative prognostic marker, but is also a target for the therapeutic monoclonal antibody Trastuzumab. In about 30% of cases, HER2/neu is expressed on acute lymphoblastic leukemia (ALL) cells and was proposed to be associated with a deleterious prognosis. Here we evaluated clinical data from 65 ALL patients (HER2/neu+, n = 17; HER2/neu-, n = 48) with a median follow-up of 19.4 months (range 0.6-176.5 months) and observed no association of HER2/neu expression with response to chemotherapy, disease free or overall survival. In vitro, treatment of primary ALL cells (CD20+HER2/neu+, CD20+HER2/neu- and CD20-HER2/neu-) with Rituximab and Trastuzumab led to activation of NK cells in strict dependence of the expression of the respective antigen. NK reactivity was more pronounced with Rituximab as compared to Trastuzumab, and combined application could lead to additive effects in cases where both antigens were expressed. Besides providing evidence that HER2/neu expression is no risk factor in ALL patients, our data demonstrates that HER2/neu can be a promising target for Trastuzumab therapy in the subset of ALL patients with the potential to improve disease outcome.