Validation of the transplant conditioning intensity (TCI) index for allogeneic hematopoietic cell transplantation

The intensity of the conditioning regimen given before allogeneic hematopoietic cell transplantation (allo-HCT) can vary substantially. To confirm the ability of the recently developed transplant conditioning intensity (TCI) score to stratify the preparative regimens of allo-HCT, we used an independent and contemporary patient cohort of 4060 transplant recipients with acute myeloid leukemia meeting inclusion criteria from the discovery study (allo-HCT in first complete remission, matched donor), but who were allografted in a more recent period (2018-2021) and were one decade older (55-75 years, median 63.4 years), we assigned them to a TCI category (low n = 1934, 48%; intermediate n = 1948, 48%, high n = 178, 4%) according to the calculated TCI score ([1-2], [2.5-3.5], [4-6], respectively), and examined the validity of the TCI category in predicting early non-relapse mortality (NRM), 2-year NRM and relapse (REL). In the unadjusted comparison, the TCI index provided a significant risk stratification for d100 and d180 NRM, NRM and REL risk. In the multivariate analysis adjusted for significant variables, there was an independent association of TCI with early NRM, NRM and REL. In summary, we confirm in contemporary treated patients that TCI reflects the conditioning regimen related morbidity and anti-leukemic efficacy satisfactorily and across other established prognostic factors.

Current incidence, severity, and management of veno-occlusive disease/sinusoidal obstruction syndrome in adult allogeneic HSCT recipients: an EBMT Transplant Complications Working Party study

The current incidence, diagnostic policy, management, and outcome of VOD/SOS at EBMT centers were studied. All centers that had performed allogeneic HSCTs in adult patients within one defined year were invited to the study. Seventy-one centers participated with a total of 2886 allogeneic transplantations and 93 cases of VOD/SOS in 2018. The cumulative incidence of VOD/SOS at day 21 was 1.8% and at day 100 2.4%. Of 67 cases with detailed data, 52 were classical and 15 (22%) late onset (>day 21). According to the EBMT criteria, 65/67 patients had at least two VOD/SOS risk factors. The severity grades were: mild 0, moderate 3, severe 29, very severe 35. Fifty-four patients were treated with defibrotide. VOD/SOS resolved in 58% of the patients, 3/3 with moderate, 22/28 with severe, and 12/33 with very severe grade (p < 0.001). By day 100, 57% of the patients were alive; 3/3 with moderate, 22/29 with severe, and 13/35 with very severe VOD/SOS (p = 0.002). In conclusion, the incidence of VOD/SOS was low. Severe and very severe grades dominated. Very severe grade predicted poor outcome compared to severe grade further supporting the concept of early diagnosis and treatment to avoid a dismal outcome.

Organ complications after CD19 CAR T-cell therapy for large B cell lymphoma: a retrospective study from the EBMT transplant complications and lymphoma working party

We investigated ≥ grade 3 (CTC-AE) organ toxicities for commercial CD19 chimeric antigen receptor T cell (CAR-T cell) products in 492 patients (Axi-Cel; n = 315; Tisa-Cel; n = 177) with Large B-cell Lymphoma in the European Society for Blood and Marrow Transplantation (EBMT) CAR-T registry. The incidence of ≥ grade 3 organ toxicities during the first 100 days after CAR-T was low and the most frequent were: renal (3.0%), cardiac (2.3%), gastro-intestinal (2.3%) and hepatic (1.8%). The majority occurred within three weeks after CAR-T cell therapy. Overall survival was 83.1% [79.8-86.5; 95% CI] at 3 months and 53.5% [49-58.4; 95% CI] at one year after CAR-T. The most frequent cause of death was tumour progression (85.1%). Non-relapse mortality was 3.1% [2.3-4.1; 95% CI] at 3 months and 5.2% [4.1-6.5; 95% CI] at one year after CAR-T. The most frequent causes of non-relapse mortality were cell-therapy-related toxicities including organ toxicities (6.4% of total deaths) and infections (4.4% of total deaths). Our data demonstrates good safety in the European real-world setting.

Treatment Strategies and Prognostic Factors in Secondary Central Nervous System Lymphoma: A Multicenter Study of 124 Patients

Secondary central nervous system lymphoma (SCNSL) is a rare and difficult to treat type of Non-Hodgkin lymphoma characterized by systemic and central nervous system (CNS) disease manifestations. In this study, 124 patients with SCNSL intensively treated and with clinical long-term follow-up were included. Initial histopathology, as divided in low-grade, other aggressive, and diffuse large B-cell lymphoma (DLBCL), was of prognostic significance. Overall response to induction treatment was a prognostic factor with early responding DLBCL-SCNSL in comparison to those non-responding experiencing a significantly better progression-free survival (PFS) and overall survival (OS). However, the type of induction regime was not prognostic for survival. Following consolidating high-dose chemotherapy and autologous stem cell transplantation (HDT-ASCT), DLBCL-SCNSL patients had better median PFS and OS. The important role of HDT-ASCT was further highlighted by favorable responses and survival of patients not responding to induction therapy and by excellent results in patients with de novo DLBCL-SCNSL (65% long-term survival). SCNSL identified as a progression of disease within 6 months of initial systemic lymphoma presentation represented a previously not appreciated subgroup with particularly dismal outcome. This temporal stratification model of SCNSL diagnosis revealed CNS progression of disease within 6 months as a promising candidate prognosticator for future studies.

Cardiovascular and metabolic determinants of quality of life in patients with cancer

AIMS

Maintaining quality of life (QoL) in patients with cancer has gathered significant interest, but little is known about its major determinants. We sought to identify determinants of QoL in patients undergoing cancer treatment as well as in treatment-naïve patients about to commence such therapy.

METHODS AND RESULTS

QoL was assessed in 283 patients with cancer using the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 questionnaire. All patients underwent a battery of tests including physical examination, resting electrocardiogram, hand grip strength, and biochemistry assessment. Using multivariable logistic regression, we found that age [odds ratio (OR) 0.954, 95% confidence interval (CI) 0.916-0.994], resting heart rate (OR 1.036, 95% CI 1.004-1.068), hand grip strength (OR 0.932, 95% CI 0.878-0.990), and the presence of cachexia (OR 4.334, 95% CI 1.767-10.631) and dyspnoea (OR 3.725, 95% CI 1.540-9.010; all P < 0.05) remained independently predictive of reduced QoL.

CONCLUSIONS

Therefore, it may be reasonable to address circumstances that are affecting muscle mass, body weight, and heart rate to maintaining QoL; however, prospective studies to test these endpoints are required.

Age-dependent increase of treatment-related mortality in older patients with aggressive B cell lymphoma: analysis of outcome, treatment feasibility, and toxicity in 1171 elderly patients with aggressive B cell lymphoma-data from phase II and III trials of the DSHNHL (German High-Grade Non-Hodgkin's Lymphoma Study Group)

In elderly patients (pts) with aggressive B cell lymphoma (aNHL), curative treatment often cannot be administered because of comorbidities and tolerability. We analyzed the influence of age in pts > 60 years receiving the R-CHOP-14 regimen within different prospective DSHNHL trials. Of the RICOVER-60 trial and CHOP-R-ESC trials, 1171 aNHL pts were included in this retrospective analysis of age-dependent event-free survival (EFS), progression-free survival (PFS), and overall survival (OS). All patients received prophylactic G-CSF, and anti-infective prophylaxis with amphotericin B mouth wash and oral fluorchinolone was optional. In the CHOP-R-ESC trials, prophylaxis was augmented to include mandatory continuous orally administered aciclovir and a pneumocystis prophylaxis with cotrimoxazole as well as oral fluorchinolones during neutropenia. The patient population was separated into 4 age groups (61-65 years, 66-70 years, 71-75 years, and 76-80 years). The results from the RICOVER-60 trial were subsequently confirmed in the following CHOP-R-ESC trials by a multivariate analysis adjusted for IPI factors and gender. Significant differences (p < 0.001) in EFS, PFS, and OS were seen between age groups (RICOVER-60). Hematotoxicity, infections, and TRM increased with age. TRM was significantly elevated in the age group 76-80 years. Therefore, this analysis shows that an age above 75 years defines an especially vulnerable patient population when being treated with chemoimmunotherapy for aNHL. Prophylactic anti-infective drugs are essential and clinically effective in reducing morbidity when treating elderly aNHL pts.

Destruction of a Microtubule-Bound MYC Reservoir during Mitosis Contributes to Vincristine's Anticancer Activity

Tightly regulated activity of the transcription factor MYC is essential for orderly cell proliferation. Upon deregulation, MYC elicits and promotes cancer progression. Proteasomal degradation is an essential element of MYC regulation, initiated by phosphorylation at Serine62 (Ser62) of the MB1 region. Here, we found that Ser62 phosphorylation peaks in mitosis, but that a fraction of nonphosphorylated MYC binds to the microtubules of the mitotic spindle. Consequently, the microtubule-destabilizing drug vincristine decreases wild-type MYC stability, whereas phosphorylation-deficient MYC is more stable, contributing to vincristine resistance and induction of polyploidy. PI3K inhibition attenuates postmitotic MYC formation and augments the cytotoxic effect of vincristine. IMPLICATIONS: The spindle's function as a docking site for MYC during mitosis may constitute a window of specific vulnerability to be exploited for cancer treatment.

Manganese causes neurotoxic iron accumulation via translational repression of amyloid precursor protein and H-Ferritin

For more than 150 years, it is known that occupational overexposure of manganese (Mn) causes movement disorders resembling Parkinson's disease (PD) and PD-like syndromes. However, the mechanisms of Mn toxicity are still poorly understood. Here, we demonstrate that Mn dose- and time-dependently blocks the protein translation of amyloid precursor protein (APP) and heavy-chain Ferritin (H-Ferritin), both iron homeostatic proteins with neuroprotective features. APP and H-Ferritin are post-transcriptionally regulated by iron responsive proteins, which bind to homologous iron responsive elements (IREs) located in the 5'-untranslated regions (5'-UTRs) within their mRNA transcripts. Using reporter assays, we demonstrate that Mn exposure repressed the 5'-UTR-activity of APP and H-Ferritin, presumably via increased iron responsive proteins-iron responsive elements binding, ultimately blocking their protein translation. Using two specific Fe2+ -specific probes (RhoNox-1 and IP-1) and ion chromatography inductively coupled plasma mass spectrometry (IC-ICP-MS), we show that loss of the protective axis of APP and H-Ferritin resulted in unchecked accumulation of redox-active ferrous iron (Fe2+ ) fueling neurotoxic oxidative stress. Enforced APP expression partially attenuated Mn-induced generation of cellular and lipid reactive oxygen species and neurotoxicity. Lastly, we could validate the Mn-mediated suppression of APP and H-Ferritin in two rodent in vivo models (C57BL6/N mice and RjHan:SD rats) mimicking acute and chronic Mn exposure. Together, these results suggest that Mn-induced neurotoxicity is partly attributable to the translational inhibition of APP and H-Ferritin resulting in impaired iron metabolism and exacerbated neurotoxic oxidative stress. OPEN SCIENCE BADGES: This article has received a badge for *Open Materials* because it provided all relevant information to reproduce the study in the manuscript. The complete Open Science Disclosure form for this article can be found at the end of the article. More information about the Open Practices badges can be found at https://cos.io/our-services/open-science-badges/.

CD31 Expression Determines Redox Status and Chemoresistance in Human Angiosarcomas

Purpose: Angiosarcomas are soft tissue sarcomas with endothelial differentiation and vasoformative capacity. Most angiosarcomas show strong constitutive expression of the endothelial adhesion receptor CD31/PECAM-1 pointing to an important role of this molecule. However, the biological function of CD31 in angiosarcomas is unknown.Experimental Design: The expression levels of CD31 in angiosarcoma cells and its effects on cell viability, colony formation, and chemoresistance were evaluated in human angiosarcoma clinical samples and in cell lines through isolation of CD31^high and CD31^low cell subsets. The redox-regulatory CD31 function linked to YAP signaling was determined using a CD31-blocking antibody and siRNA approach and was further validated in CD31-knockout endothelial cells.Results: We found that most angiosarcomas contain a small CD31^low cell population. CD31^low cells had lost part of their endothelial properties and were more tumorigenic and chemoresistant than CD31^high cells due to more efficient reactive oxygen species (ROS) detoxification. Active downregulation of CD31 resulted in loss of endothelial tube formation, nuclear accumulation of YAP, and YAP-dependent induction of antioxidative enzymes. Addition of pazopanib, a known enhancer of proteasomal YAP degradation resensitized CD31^low cells for doxorubicin resulting in growth suppression and induction of apoptosis.Conclusions: Human angiosarcomas contain a small aggressive CD31^low population that have lost part of their endothelial differentiation programs and are more resistant against oxidative stress and DNA damage due to intensified YAP signaling. Our finding that the addition of YAP inhibitors can resensitize CD31^low cells toward doxorubicin may aid in the rational development of novel combination therapies to treat angiosarcomas. Clin Cancer Res; 24(2); 460-73. ©2017 AACR.

Nuclear Trapping through Inhibition of Exosomal Export by Indomethacin Increases Cytostatic Efficacy of Doxorubicin and Pixantrone

PURPOSE

Although R-CHOP-based immunochemotherapy cures significant proportions of patients with aggressive B-cell lymphoma, tumor cell susceptibility to chemotherapy varies, with mostly fatal outcome in cases of resistant disease. We and others have shown before that export of cytostatic drugs contributes to drug resistance. Now we provide a novel approach to overcome exosome-mediated drug resistance in aggressive B-cell lymphomas.

EXPERIMENTAL DESIGN

We used well-established centrifugation protocols to purify exosomes from DLBCL cell lines and detected anthracyclines using FACS and HPLC. We used shRNA knockdown of ABCA3 to determine ABCA3 dependence of chemotherapy susceptibility and monitored ABCA3 expression after indomethacin treatment using qPCR. Finally, we established an in vivo assay using a chorioallantoic membrane (CAM) assay to determine the synergy of anthracycline and indomethacin treatment.

RESULTS

We show increased efficacy of the anthracycline doxorubicin and the anthracenedione pixantrone by suppression of exosomal drug resistance with indomethacin. B-cell lymphoma cells in vitro efficiently extruded doxorubicin and pixantrone, in part compacted in exosomes. Exosomal biogenesis was critically dependent on the expression of the ATP-transporter A3 (ABCA3). Genetic or chemical depletion of ABCA3 augmented intracellular retention of both drugs and shifted the subcellular drug accumulation to prolonged nuclear retention. Indomethacin increased the cytostatic efficacy of both drugs against DLBCL cell lines in vitro and in vivo in a CAM assay.

CONCLUSIONS

We propose pretreatment with indomethacin toward enhanced antitumor efficacy of anthracyclines and anthracenediones.

A novel selective small-molecule PI3K inhibitor is effective against human multiple myeloma in vitro and in vivo

Developing effective therapies against multiple myeloma (MM) is an unresolved challenge. Phosphatidylinositol-3-kinase (PI3K) activation may be associated with tumor progression and drug resistance, and inhibiting PI3K can induce apoptosis in MM cells. Thus, targeting of PI3K is predicted to increase the susceptibility of MM to anticancer therapy. The lead compound of a novel class of PI3K inhibitors, BAY80-6946 (IC50=0.5 nM against PI3K-α), was highly efficacious in four different MM cell lines, where it induced significant antitumoral effects in a dose-dependent manner. The compound inhibited cell cycle progression and increased apoptosis (P<0.001 compared with controls). Moreover, it abrogated the stimulation conferred by insulin-like growth-factor-1, a mechanism relevant for MM progression. These cellular effects were paralleled by decreased Akt phosphorylation, the main downstream target of PI3K. Likewise, profound antitumoral activity was observed ex vivo, as BAY80-6946 significantly inhibited proliferation of freshly isolated myeloma cells from three patients (P<0.001 compared with vehicle). In addition, BAY80-6946 showed convincing in vivo activity against the human AMO-1 and MOLP-8 myeloma cell lines in a preclinical murine xenograft model, where treatment with 6 mg/kg every other day for 2 weeks reduced the cell numbers by 87.0% and 69.3%, respectively (P<0.001 compared with vehicle), without overt toxicity in treated animals.

Tyrosinekinase inhibition facilitates cooperation of transcription factor SALL4 and ABC transporter A3 towards intrinsic CML cell drug resistance

Although BCR-ABL1 tyrosine kinase inhibitors reliably induce disease remission for patients with chronic myeloid leukaemia (CML), unlimited extension of therapy is necessary to prevent relapse from persistent leukaemic cells. Here, we analysed model cell lines and primary CML cells for the expression and functions of the ABC transporter A3 (ABCA3) as well as the embryonic stem cell-associated transcription factor SALL4. ABCA3 protected leukaemic cells from the cytotoxic effects of the tyrosine kinase inhibitors imatinib, dasatinib, and nilotinib. In the surviving cells, exposure to tyrosine kinase inhibitors significantly enhanced ABCA3 expression in vivo and in vitro, and was associated with increased expression of SALL4, which binds the ABCA3 promoter. Inhibition of ABCA3 or SALL4 by genetic silencing or indomethacin, but not interferon gamma, interrupted SALL4-dependent regulation of ABCA3 and restored susceptibility of leukaemic cells to tyrosine kinase inhibition. Tyrosine kinase inhibitor exposure facilitates a protective loop of SALL4 and ABCA3 cooperation in persistent leukaemic cells.

Multikinase inhibitor sorafenib exerts cytocidal efficacy against Non-Hodgkin lymphomas associated with inhibition of MAPK14 and AKT phosphorylation

Intracellular signal transduction by kinase-mediated phosphorylation is essential for the survival and growth of lymphoma cells. This study analysed the multikinase inhibitor sorafenib for its cytotoxic activity against lymphoma cells. We found that sorafenib reduced cell viability at low micromolar concentrations in a time-dependent manner in cell lines and primary cell suspensions representing major types of aggressive B- and T-cell lymphomas. In cells surviving short term exposure, proliferative arrest occurred leading to complete loss of in vitro clonogenicity. Previously described sorafenib targets within the RAF kinase family were found to be expressed and phosphorylated in all cell lines, and sorafenib perturbed the activation of classical RAF/MEK/ERK pathway targets. However, using a global phoshoprotein array, the most consistent downstream effect of sorafenib in NHL cells was the inhibition of mitogen-activated protein kinase 14 (MAPK14) and panAKT phosphorylation. In conclusion, sorafenib has significant in vitro efficacy against aggressive B- and T-cell lymphoma cells, associated with inhibition of MAPK14 and panAKT.

ABC transporter A3 facilitates lysosomal sequestration of imatinib and modulates susceptibility of chronic myeloid leukemia cell lines to this drug

BACKGROUND

Inhibition of BCR-ABL tyrosine kinase activity has evolved as a mainstay of therapy for patients with chronic myeloid leukemia. However, a fraction of leukemic cells persists under targeted therapy and can lead to disease progression on cessation of treatment.

DESIGN AND METHODS

We analyzed bone marrow progenitor cells with the side population phenotype, and characterized the role of the intracellular ABC transporter A3 in imatinib detoxification.

RESULTS

BCR-ABL-positive leukemic cells contribute to the side population cell compartment in untreated patients. Such leukemic side population cells, as well as CD34-positive progenitors from chronic myeloid leukemia samples, strongly express the intracellular ABCA3. Functionally, ABCA3 levels are critical for the susceptibility of chronic myeloid leukemia blast cell lines to specific BCR-ABL inhibition by imatinib. The transporter is localized in the limiting membrane of lysosomes and multivesicular bodies, and intracellular [(14)C]-labeled imatinib accumulates in such organelles. The lysosomal storage capacity increases with ABCA3 expression, thus regulating imatinib sequestration.

CONCLUSIONS

The intracellular ABC transporter A3 is expressed in chronic myeloid leukemia progenitor cells and may contribute to intrinsic imatinib resistance by facilitating lysosomal sequestration in chronic myeloid leukemia cells.

Characterization of HLA-DR-restricted T-cell epitopes derived from human proteinase 3

Human proteinase 3 (PRTN3) is a leukemia-associated antigen specifically recognized by CD8+ cytotoxic T-lymphocytes (CTL). PRTN3 also has been shown to elicit both antibody responses and T-cell proliferation in patients with Wegener's granulomatosis. In order to improve current vaccines that aim to stimulate CTL without inducing harmful autoimmune disease, it is necessary to study the role of PRTN3-specific CD4+ T-helper (TH) and CD4+ T-regulatory (Treg) cells. Since both TH and Treg cells recognize antigens in the context of HLA-class-II-molecules, identification of HLA-class-II-associated peptide-epitopes from self-antigens such as PRTN3 is required. Here, we analyzed T-cell responses against proteinase 3 using synthetic peptides predicted to serve as HLA-DR-restricted epitopes. We first screened a panel of ten epitope peptide candidates selected with the TEPITOPE program and found that nine out of ten peptides induced PRTN3 peptide-specific proliferation of T-cells with precursor frequencies of 0-1.1 x 10(-6). For one peptide-epitope, PRTN3(235), T-cell-clones were demonstrated to be capable of recognizing naturally processed protein antigen in a HLA-DR-restricted fashion. PRTN3(235)-specific T-cells could be stimulated from the blood of healthy individuals with multiple HLA-DR-genotypes. In summary, the identified PRTN3(235)-epitope can be used to study the role of CD4+ TH- and Treg-cells in immune responses against PRTN3 in leukemia patients and patients with Wegener's disease.

Intracellular ABC transporter A3 confers multidrug resistance in leukemia cells by lysosomal drug sequestration

Multidrug resistance (MDR) seriously limits the efficacy of chemotherapy in patients with cancer and leukemia. Active transport across membranes is essential for such cellular drug resistance, largely provided by ATP-binding cassette (ABC) transport proteins. Intracellular drug sequestration contributes to MDR; however, a genuine intracellular ABC transport protein with MDR function has not yet been identified. Analyzing the intrinsic drug efflux capacity of leukemic stem cells, we found the ABC transporter A3 (ABCA3) to be expressed consistently in acute myeloid leukemia (AML) samples. Greater expression of ABCA3 is associated with unfavorable treatment outcome, and in vitro, elevated expression induces resistance toward a broad spectrum of cytostatic agents. ABCA3 remains localized within the limiting membranes of lysosomes and multivesicular bodies, in which cytostatics are efficiently sequestered. In addition to AML, we also detected ABCA3 in a panel of lymphohematopoietic tissues and transformed cell lines. In conclusion, we identified subcellular drug sequestration mediated by the genuinely intracellular ABCA3 as being a clinically relevant mechanism of intrinsic MDR.

[Mesenchymal stem cells from bone marrow. Phenotype, aspects of biology, and clinical perspectives]

BACKGROUND

Since their initial description by Friedenstein et al. 30 years ago, mesenchymal stem cells have been characterized as a cell population of the bone marrow, which is easily accessible and readily manageable for in vitro manipulation.

RESULTS

Cell biology studies have delineated the phenotype of mesenchymal stem cells, optimized the conditions for in vitro expansion, and documented their differentiation capacity along mesodermal lineages. First clinical applications as an adjunct to stem cell transplantation regimens have shown some potential in osteogenic regeneration as well as immunosuppressive effects after allogeneic stem cell transplantation. Animal studies have further shown, that mesenchymal stem cells may serve as vehicles for the transfer of genetic material. Preclinical studies remain, however, to answer numerous questions with regard to populational heterogeneity and the physiological roles of this cell compartment.

CONCLUSION

Further preclinical studies as well as clinical cell therapy studies are essential to fully exploit the potential of mesenchymal stem cells in regenerative medicine, cellular immunotherapy, and gene therapy.

CD45 monoclonal antibody-mediated cytolysis of human NK and T lymphoma cells

BACKGROUND AND OBJECTIVES

The CD45 rat monoclonal IgG2b antibodies YTH24.5 and YTH54.12 act synergistically to produce cytolysis of normal lymphocytes and have been safely given to patients in conditioning regimens for allogeneic stem cell transplantation. The antibodies are not lytic for hematopoietic stem cells, but the depletion of the lymphoid lineage cells is profound and sustained.

DESIGN AND METHODS

We evaluated the YTH24.5 and YTH54.12 pair for complement-dependent cytotoxicity (CDC), antibody-dependent cell-mediated cytotoxicity (ADCC), and apoptotic and antiproliferative effects against a panel of non-Hodgkin's lymphoma (NHL) cell lines and against primary specimens.

RESULTS

Significant CDC activity was observed against two of two NK and one of four T lymphoma cell lines; moderate activity was seen against two of four T, and four of eight B lymphoma cell lines. In the responding cell lines, the lytic activity of YTH24.5 and YTH54.12 was as least as strong as that of alemtuzumab or antithymocyte globulin. The combination of YTH24.5 and YTH54.12 also induced ADCC in one of two NK and two of four T lymphoma cell lines, as well as three primary specimens, but was ineffective in B-NHL. The antibodies decreased viability in two of two NK and one lymphoma cell line, measurable as apoptosis or direct cell death in the cell lines NK92 and CEM, respectively. In a tumor model of Jurkat lymphoma in SCID mice, administration of YTH24.5 and YTH54.12 impaired local tumor growth and delayed systemic disease progression.

INTERPRETATION AND CONCLUSIONS

CD45 antibodies YTH24.5 and YTH54.12 have lytic activity against NK and T lymphoma cells via CDC and ADCC, are effective in a preclinical tumor model, and may be candidates for immunotherapeutic approaches to the treatment of human NK and T cell lymphoma.

Mesengenic progenitor cells derived from human placenta

Progenitor cells with differentiation capacity along multiple mesengenic lineages are attractive tools for numerous purposes in regenerative medicine. Such mesengenic progenitor cells have been isolated from adult mammalian bone marrow, and we here report placental tissue as an alternative source for these cells. By means of dissection/proteinase digestion techniques, high numbers of viable mononuclear cells were harvested from human placenta at term, and a mesenchymal cell population with characteristic expression of CD9, CD29, and CD73 was obtained in culture. The in vitro growth behavior of such placenta-derived mesengenic cells was similar to that of human bone marrow mesengenic progenitor cells. After in vitro propagation for more than three passages the cells were exclusively of maternal origin. Differentiation experiments showed differentiation potential along osteogenic, chondrogenic, adipogenic, and myogenic lineages. In conclusion, we propose human term placenta as an easily accessible, ample source of multipotent mesengenic progenitor cells.

A distinct "side population" of cells in human tumor cells: implications for tumor biology and therapy

Stem cells have an extensive capacity to proliferate, differentiate and self-renew. In many mammals, including humans, an adult stem cell subpopulation termed the "side population" (SP) has been identified. SP cells can rapidly efflux lipophilic fluorescent dyes to produce a characteristic profile based on fluorescence-activated flow cytometric analysis. Previous studies have demonstrated SP cells in bone marrow obtained from patients with acute myeloid leukemia, suggesting that these cells might be candidate leukemic stem cells, and recent studies have found a SP of tumor progenitor cells in human solid tumors. These new data indicate that the ability of malignant SP cells to expel anticancer drugs may directly improve their survival and sustain their clonogenicity during exposure to cytostatic drugs, allowing disease recurrence when therapy is withdrawn. Identification of a tumor progenitor population with intrinsic mechanisms for cytostatic drug resistance might also provide clues for improved therapeutic intervention.

Diagnostische Wertigkeit des Nachweises von Antikorpern gegen Candida-Keimschlauchantigene bei einer Patientin mit hepatolienaler Candidose. Diagnostic value of antibody detection against Candida germ tube antigens in a patient with hepatosplenic candidosis

In the case of a 53-year-old woman with acute myeloid leukaemia and fever in late aplasia after chemotherapy, invasive mycosis with characteristic involvement of liver and spleen was diagnosed. For the serological identification of Candida in the early phase of the infection, methods for the detection of antibodies against Candida antigens were compared. By ELISA-based detection of IgM and IgG antibodies against a mixture of Candida antigens (ESR 117G and 117M, Virion-Serion, Wurzburg, Germany) evidence for invasive candidosis was obtained significantly earlier (22 days) when compared with the immunofluorescence detection of IgG antibodies against Candida albicans germ tube antigens (Vircell, Granada, Spain). In the case of this patient, the detection of a humoral response against Candida germ tube antigens was of little diagnostic value.

ABC transporter ABCA3 is expressed in acute myeloid leukemia blast cells and participates in vesicular transport

Drug resistance is a major issue in the treatment of acute myeloid leukemia (AML), and drug efflux by ATP-binding-cassette (ABC) transporters is one of the main mechanism involved in this resistance. We determined the prevalence of the intracellular transporter ABCA3 in specimens from patients with AML, and addressed its biology with attention to intracellular compartmentalization.

A distinct "side population" of cells with high drug efflux capacity in human tumor cells

A subset of stem cells, termed the "side population" (SP), has been identified in several tissues in mammalian species. These cells maintain a high efflux capability for antimitotic drugs. We have investigated whether functionally equivalent stem cells also may be detected in human cancers. We initially examined primary tumor cells from 23 patients with neuroblastoma and cell lines derived from a range of other tumors. A distinct SP was found in neuroblastoma cells from 15 of 23 patients (65%). The SP was capable of sustained expansion ex vivo and showed evidence for asymmetric division, generating both SP and non-SP progeny. These cells also expressed high levels of ABCG2 and ABCA3 transporter genes and had a greater capacity to expel cytotoxic drugs, such as mitoxantrone, resulting in better survival. A SP also was detected in breast cancer, lung cancer, and glioblastoma cell lines, suggesting that this phenotype defines a class of cancer stem cells with inherently high resistance to chemotherapeutic agents that should be targeted during the treatment of malignant disease.

An in vivo propagated human acute myeloid leukemia expressing ABCA3

Analyzing the regenerative compartment in the blast cell population of patients with acute myeloid leukemia (AML) may yield important insights into the mechanisms of disease progression. Here we present findings with a human AML cell line (AML-SP1), initiated from leukemic precursor cells and consecutively propagated by serial xenotransplantation in vivo. AML-SP1 maintained the characteristics of a human AML, consistently exhibiting a small leukemic side population (SP) of blast cells with high Hoechst 33342 exclusion. In the AML-SP1 line, an increased expression of the ABC transporters MDR1, MRP, ABCG2 and ABCA3 was found in the SP cells. The detection of ABCA3 in leukemic progenitor cells merits further investigation with regard to intracellular drug transport in AML blast cells. In vivo propagation of leukemias, such as AML-SP1 is a model system of maintaining the populational heterogeneity of AML disease, especially the unique characteristics of leukemic SP cells.

Complement-fixing CD45 monoclonal antibodies to facilitate stem cell transplantation in mouse and man

Broadening the applicability of stem cell therapies requires safer preparative regimens for patients. The CD45 antigen is present on all cells of the hematopoietic lineage, and using a murine model, we determined whether a lytic CD45 monoclonal antibody could produce persistent aplasia and whether it could facilitate syngeneic or allogeneic stem cell engraftment. After its systemic administration, we found that all leukocyte subsets in peripheral blood were markedly diminished, but only the effect on the lymphoid compartment was sustained and marrow progenitor cells were spared from destruction. Given the transient effects of the monoclonal antibody on myelopoiesis and the more persistent effects on lymphopoiesis, we asked whether this agent could contribute to donor hemopoietic engraftment after subablative transplantation. Treatment with anti-CD45 alone did not enhance syngeneic engraftment, consistent with its inability to destroy progenitor cells and permit competitive repopulation with syngeneic donor stem cells. By contrast, the combination of anti-CD45 and an otherwise inactive dose of total-body irradiation allowed engraftment of H2 fully allogeneic donor stem cells. We attribute this result to the recipient immunosuppression produced by depletion of CD45-positive lymphocytes. We next assessed a pair of unconjugated rat anti-human CD45 monoclonal antibodies (MAbs), YTH54.12 and YTH25.4, in a clinical trial in patients who were to receive stem cell transplantation for acute leukemia. The maximum tolerated dose of these MAbs, 400 microg/kg/day, produced a pattern of response identical to that seen in the mice, with marked reductions in circulating lymphoid and myeloid cells and sparing of early marrow progenitors. In two of three patients with active leukemia, the MAbs also produced a decrease in the percentage of leukemic blast cells in bone marrow. These pre-clinical and clinical results warrant further evaluation of anti-CD45 MAbs in subablative preparative regimens for stem cell transplantation.

Cells of the hepatic side population contribute to liver regeneration and can be replenished with bone marrow stem cells

BACKGROUND AND OBJECTIVES

The aim of this study was to determine whether Hoechst effluxing side population cells isolated from murine liver represent hepatic stem cells, and to examine whether hepatic side population cells arise from bone marrow side population cells.

DESIGN AND METHODS

Side population cells were isolated from murine liver by flow cytometry after Hoechst staining and injected directly into murine livers of animals pre-treated with the hepatotoxin 3,5 diethoxy carbonyl-1, 4-dihydrocollidine (DDC). Y-chromosome in situ hybridization was used to track donor cells in the livers. In addition, bone marrow side population cells were stably engrafted into the hematopoietic system of sublethally irradiated recipients and CD45 alleleic staining and Y-chromosome in situ hybridization were used to track side population cell progeny in the liver.

RESULTS

In vitro, CD45pos and CD45neg hepatic SP cells gave rise to hematopoietic colonies and mixed colonies of hematopoietic and hepatic differentiation. After orthotopic liver cell transplantation, donor hepatic side population cells contributed to the regeneration of mature liver parenchyma and bile duct epithelium. After transplantation of bone marrow side population cells, both CD45pos and CD45neg hepatic side population cells were partially derived from donor stem cells and could be recruited to repair liver damage after treatment with DDC.

INTERPRETATION AND CONCLUSIONS

These findings introduce hepatic side population cells as a facultative liver-regenerating population, reveal interchangeability of tissue stem cells at the level of the side population, and suggest that bone marrow-derived side population cells might be exploited for the repair of diseased or damaged liver.

Anti-CD45-mediated cytoreduction to facilitate allogeneic stem cell transplantation

The CD45 antigen is present on all cells of the hematopoietic lineage. Using a murine model, we have determined whether a lytic CD45 monoclonal antibody can produce persistent aplasia and whether it could facilitate syngeneic or allogeneic stem cell engraftment. After its systemic administration, we found saturating quantities of the antibody on all cells expressing the CD45 antigen, both in marrow and in lymphoid organs. All leukocyte subsets in peripheral blood were markedly diminished during or soon after anti-CD45 treatment, but only the effect on the lymphoid compartment was sustained. In contrast to the prolonged depletion of T and B lymphocytes from the thymus and spleen, peripheral blood neutrophils began to recover within 24 hours after the first anti-CD45 injection and marrow progenitor cells were spared from destruction, despite being coated with saturating quantities of anti-CD45. Given the transient effects of the monoclonal antibody on myelopoiesis and the more persistent effects on lymphopoiesis, we asked whether this agent could contribute to donor hematopoietic engraftment following nonmyeloablative transplantation. Treatment with anti-CD45 alone did not enhance syngeneic engraftment, consistent with its inability to destroy progenitor cells and permit competitive repopulation with syngeneic donor stem cells. By contrast, the combination of anti-CD45 and an otherwise inactive dose of total-body irradiation allowed engraftment of H2 fully allogeneic donor stem cells. We attribute this result to the recipient immunosuppression produced by depletion of CD45(+) lymphocytes. Monoclonal antibodies of this type may therefore have an adjunctive role in nonmyeloablative conditioning regimens for allogeneic stem cell transplantation.

Stem cells: a minireview

The identification of adult-derived stem cells which maintain plasticity throughout the course of a lifetime, has transformed the field of stem cell biology. Bone marrow derived hematopoietic stem cells (HSC) are the most well-characterized population of these multipotential cells. First identified for their ability to reconstitute blood lineages and rescue lethally irradiated hosts, these cells have also been shown to differentiate and integrate into skeletal muscle, cardiac myocytes, vascular endothelium, liver, and brain tissue. Various populations of HSC are being studied, exploiting cell surface marker expression, such as Sca-1, c-kit, CD34, and lin; as well as the abilityto efflux the vital dye Hoecsht 33342. Detection of engrafted donor derived cells into various tissue types in vivo is a laborious process and may involve detection of beta-galactosidase via colorimetric reaction or antibody labeling or green fluorescent protein (GFP) via fluorescence microscopy, as well as in situ hybridization to detect the Y-chromosome. Using these techniques, the search has begun for tissue specific stem cells capable of host tissue regeneration, self renewal, and transdifferentiation. Caution is urged when interpreting these types of experiments because although they are stimulating, limitations of the technologies may provide misleading results.

A leukemic stem cell with intrinsic drug efflux capacity in acute myeloid leukemia

The hematopoietic stem cell underlying acute myeloid leukemia (AML) is controversial. Flow cytometry and the DNA-binding dye Hoechst 33342 were previously used to identify a distinct subset of murine hematopoietic stem cells, termed the side population (SP), which rapidly expels Hoechst dye and can reconstitute the bone marrow of lethally irradiated mice. Here, the prevalence and pathogenic role of SP cells in human AML were investigated. Such cells were found in the bone marrow of more than 80% of 61 patients and had a predominant CD34(low/-) immunophenotype. Importantly, they carried cytogenetic markers of AML in all 11 cases of active disease examined and in 2 out of 5 cases in complete hematological remission. Comparison of daunorubicin and mitoxantrone fluorescence emission profiles revealed significantly higher drug efflux from leukemic SP cells than from non-SP cells. Three of 28 SP cell transplants generated overt AML-like disease in nonobese diabetic--severe combined immunodeficient mice. Low but persistent numbers of leukemic SP cells were detected by molecular and immunological assays in half of the remaining mice. Taken together, these findings indicate that SP cells are frequently involved in human AML and may be a target for leukemic transformation. They also suggest a mechanism by which SP cells could escape the effects of cytostatic drugs and might eventually contribute to leukemia relapse. (Blood. 2001;98:1166-1173)

Pin1 is overexpressed in breast cancer and cooperates with Ras signaling in increasing the transcriptional activity of c-Jun towards cyclin D1

Phosphorylation on serines or threonines preceding proline (Ser/Thr-Pro) is a major signaling mechanism. The conformation of a subset of phosphorylated Ser/Thr-Pro motifs is regulated by the prolyl isomerase Pin1. Inhibition of Pin1 induces apoptosis and may also contribute to neuronal death in Alzheimer's disease. However, little is known about the role of Pin1 in cancer or in modulating transcription factor activity. Here we report that Pin1 is strikingly overexpressed in human breast cancers, and that its levels correlate with cyclin D1 levels in tumors. Overexpression of Pin1 increases cellular cyclin D1 protein and activates its promoter. Furthermore, Pin1 binds c-Jun that is phosphorylated on Ser63/73-Pro motifs by activated JNK or oncogenic Ras. Moreover, Pin1 cooperates with either activated Ras or JNK to increase transcriptional activity of c-Jun towards the cyclin D1 promoter. Thus, Pin1 is up-regulated in human tumors and cooperates with Ras signaling in increasing c-Jun transcriptional activity towards cyclin D1. Given the crucial roles of Ras signaling and cyclin D1 overexpression in oncogenesis, our results suggest that overexpression of Pin1 may promote tumor growth.

Hypercoagulability in a patient with hypodysfibrinogenemia: implications for clinical management

Dysfibrinogenemia accounts for approximately 0.7% of thrombophilia in patients with venous thromboembolic disease. In 20% of these patients, plasma thrombophilic dysfibrinogen is below 1.0 mg/ml, defining hypodysfibrinogenemia. We describe a young female patient, in whom hypodysfibrinogenemia was the cause of several severe thromboembolic events which occurred even under oral anticoagulation monitored by a standard prothrombin time (PT) test. In this patient, the standard PT test according to Quick underestimated the plasma coagulability in vivo, presumably due to the low levels of dysfunctional fibrinogen as the substrate of the thromboplastin reagent. A PT test supplemented with bovine plasma fibrinogen (Thrombotest) revealed lower fibrinogen-independent international normalized ratio (INR) values in the proposita on oral anticoagulation compared to a control group with eufibrinogenemia. Monitoring therapy with the fibrinogen-independent Thrombotest secured safe anticoagulation in this patient. We suggest to consider PT tests with exogenous fibrinogen (e.g. Thrombotest) to monitor oral anticoagulation in the rare thrombophilic patients with hypodysfibrinogenemia.

Plasmacytosis in acute myeloid leukemia: two cases of plasmacytosis and increased IL-6 production in the AML blast cells

An increased plasma cell count in the bone marrow occurs in a subgroup of patients with acute myeloid leukemia (AML). The pathogenic mechanism for this plasmacytosis is unclear. In this report we describe two patients with AML and plasmacytosis who shared some features of their diseases. The morphological subtypes were AML M4 and M4eo; the leukemias were secondary to cytotoxic pretreatment, and complex cytogenetic changes were found in the leukemic cells of both patients. There was a marked increase in the number of bone marrow plasma cells in both cases and no monoclonal immunoglobulin was detectable. The IgH-CDR3 gene scan depicted a monoclonal IgH rearrangement in the bone marrow cells of one patient. Analysis of the cytokine production of the leukemic cells showed a high production of IL-6 of the leukemic blast cells in the in vitro cell culture and a high cytoplasmic IL-6 in the leukemic cells as revealed by immunocytology. We describe the clinical picture of a type of secondary AML with FAB M4 morphology associated with bone marrow plasmacytosis. We suggest that paracrine growth stimulation of plasma cells by paraneoplastic IL-6 production of the leukemic blast cells contributes to the plasmacytosis observed in patients with AML.

Renin in acute myeloid leukaemia blasts

Hypokalaemia is a clinical phenomenon in patients with acute myeloid leukaemia (AML) to which activation of the renin-angiotensin system (RAS) may contribute. Recently monocytes were found to express renin, the key initializing enzyme of the RAS. By RT/PCR, transcripts for renin were detected in four of 18 bone marrow samples from patients with AML. Three leukaemic cell lines, isolated monocytes, bone marrow stromal cells and 25 peripheral blood and 24 bone marrow samples of normal controls were negative for renin transcripts. In view of the importance of local RAS in other tissues, the expression of renin in the bone marrow of AML patients warrants further investigation.