Publications by authors named "Christian Peschel"

212 Publications

Cathepsin K maintains the compartment of bone marrow T lymphocytes in vivo.

Immun Inflamm Dis 2021 Feb 16. Epub 2021 Feb 16.

Technical University of Munich, School of Medicine, Klinikum rechts der Isar, Department of Internal Medicine III - Hematology and Oncology, Laboratory of Stem Cell Physiology, Munich, Germany.

In this study, we investigated the influence of the loss of cathepsin K (Ctsk) gene on the hematopoietic system in vitro and in vivo. We found that cultures with lineage SCA1 KIT (LSK) cells on Ctsk deficient stromal cells display reduced colony formation and proliferation, with increased differentiation, giving rise to repopulating cells with reduced ability to repopulate the donor LSKs and T cell compartments in the bone marrow (BM). Subsequent in vivo experiments showed impairment of lymphocyte numbers, but, gross effects on early hematopoiesis or myelopoiesis were not found. Most consistently in in vivo experimental settings, we found a significant reduction of (donor) T cell numbers in the BM. Lymphocyte deregulation is also found in transplantation experiments, which revealed that Ctsk is required for optimal regeneration of small populations of T cells, particularly in the BM, but also of thymic B cells. Interestingly, cell nonautonomous Ctsk regulates both B and T cell numbers, but T cell numbers in the BM require an additional autonomous Ctsk-dependent process. Thus, we show that Ctsk is required for the maintenance of hematopoietic stem cells in vitro, but in vivo, Ctsk deficiency most strongly affects lymphocyte homeostasis, particularly of T cells in the BM.
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http://dx.doi.org/10.1002/iid3.412DOI Listing
February 2021

Loss of the Fanconi anemia-associated protein NIPA causes bone marrow failure.

J Clin Invest 2020 06;130(6):2827-2844

Department of Internal Medicine I, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.

Inherited bone marrow failure syndromes (IBMFSs) are a heterogeneous group of disorders characterized by defective hematopoiesis, impaired stem cell function, and cancer susceptibility. Diagnosis of IBMFS presents a major challenge due to the large variety of associated phenotypes, and novel, clinically relevant biomarkers are urgently needed. Our study identified nuclear interaction partner of ALK (NIPA) as an IBMFS gene, as it is significantly downregulated in a distinct subset of myelodysplastic syndrome-type (MDS-type) refractory cytopenia in children. Mechanistically, we showed that NIPA is major player in the Fanconi anemia (FA) pathway, which binds FANCD2 and regulates its nuclear abundance, making it essential for a functional DNA repair/FA/BRCA pathway. In a knockout mouse model, Nipa deficiency led to major cell-intrinsic defects, including a premature aging phenotype, with accumulation of DNA damage in hematopoietic stem cells (HSCs). Induction of replication stress triggered a reduction in and functional decline of murine HSCs, resulting in complete bone marrow failure and death of the knockout mice with 100% penetrance. Taken together, the results of our study add NIPA to the short list of FA-associated proteins, thereby highlighting its potential as a diagnostic marker and/or possible target in diseases characterized by hematopoietic failure.
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http://dx.doi.org/10.1172/JCI126215DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7260023PMC
June 2020

MOR202, a novel anti-CD38 monoclonal antibody, in patients with relapsed or refractory multiple myeloma: a first-in-human, multicentre, phase 1-2a trial.

Lancet Haematol 2020 May 11;7(5):e381-e394. Epub 2020 Mar 11.

Translational Oncology, Comprehensive Cancer Center Mainfranken, University Hospital of Würzburg, Würzburg, Germany.

Background: Treatment of multiple myeloma is not curative, but targeting CD38 improves patient survival. To further explore this therapeutic approach, we investigated the safety and activity of MOR202, a novel monoclonal antibody targeting CD38, in patients with multiple myeloma.

Methods: This is a multicentre, open-label, phase 1-2a trial done at ten hospitals in Germany and Austria. Enrolled patients were aged 18 years or older with relapsed or refractory multiple myeloma and Karnofsky performance status of 60% or higher. Patients were assigned to the different treatment regimens with MOR202 ranging between 0·01 mg/kg and 16 mg/kg in a 3 + 3 design. Dose-escalation and expansion was done either with MOR202 intravenous infusions alone (MOR202 q2w [twice a week] and q1w [weekly] groups) or in combination with dexamethasone (MOR202 with dexamethasone group), with dexamethasone plus pomalidomide (MOR202 with dexamethasone plus pomalidomide group) or plus lenalidomide (MOR202 with dexamethasone plus lenalidomide group). Primary endpoints were safety, MOR202 maximum tolerated dose (or recommended dose) and regimen, and immunogenicity. The primary analysis was assessed in the safety population, which included patients who received at least one dose of any study drug. This trial is registered with ClinicalTrials.gov, NCT01421186.

Findings: Between Aug 24, 2011, and Aug 1, 2017, 91 patients were treated, 35 with MOR202 monotherapy, and 56 with MOR202 combination regimens (18 in the MOR202 with dexamethasone group, 21 in the MOR202 with dexamethasone plus pomalidomide group, and 17 in the MOR202 with dexamethasone plus lenalidomide group). MOR202 intravenous infusions were safely administered within 30 min. Infusion-related reactions occurred in 14 (40%) of 35 patients receiving MOR202 monotherapy without steroids, and in four (7%) of 56 patients receiving MOR202 combination treatment. MOR202 maximum tolerated dose was not reached and the recommended regimens were MOR202 administered as an intravenous infusion for 30 min at doses up to 16 mg/kg with dexamethasone (40 mg), or in combination with dexamethasone plus lenalidomide (25 mg) or pomalidomide (4 mg). 35 (38%) of 91 patients developed lymphopenia, 30 (33%) developed neutropenia, and 27 (30%) developed leukopenia; these were the most common grade 3 or higher treatment-emergent adverse events. Serious adverse events were reported in 51 (56%) of 91 patients. None of the deaths were associated with MOR202. One pomalidomide-associated death occurred in the MOR202 with dexamethasone plus pomalidomide group. No anti-MOR202 antibodies were detected in patients.

Interpretation: MOR202 is safe and its clinical activity in patients with relapsed or refractory multiple myeloma is promising. Further clinical investigations of combinations with an immunomodulatory drug and dexamethasone are recommended.

Funding: MorphoSys AG.
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http://dx.doi.org/10.1016/S2352-3026(19)30249-2DOI Listing
May 2020

Inhibition of PLK1 by capped-dose volasertib exerts substantial efficacy in MDS and sAML while sparing healthy haematopoiesis.

Eur J Haematol 2020 Feb 8;104(2):125-137. Epub 2019 Dec 8.

Medical Department III for Haematology and Oncology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.

Introduction: Targeting the cell cycle machinery represents a rational therapeutic approach in myelodysplastic syndromes (MDS) and secondary acute myeloid leukemia (sAML). Despite substantial response rates, clinical use of the PLK inhibitor volasertib has been hampered by elevated side effects such as neutropenia and infections.

Objectives: The primary objective was to analyse whether a reduced dose of volasertib was able to limit toxic effects on the healthy haematopoiesis while retaining its therapeutic effect.

Methods: Bone marrow mononuclear cells (BMMNCs) of patients with MDS/sAML (n = 73) and healthy controls (n = 28) were treated with volasertib (1 μM to 1 nM) or vehicle control. Short-term viability analysis was performed by flow cytometry after 72 hours. For long-term viability analysis, colony-forming capacity was assessed after 14 days. Protein expression of RIPK3 and MCL-1 was quantified via flow cytometry.

Results: Reduced dose levels of volasertib retained high cell death-inducing efficacy in primary human stem and progenitor cells of MDS/sAML patients without affecting healthy haematopoiesis in vitro. Interestingly, volasertib reduced colony-forming capacity and cell survival independent of clinical stage or mutational status.

Conclusions: Volasertib offers a promising therapeutic approach in patients with adverse prognostic profile. RIPK3 and MCL-1 might be potential biomarkers for sensitivity to volasertib treatment.
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http://dx.doi.org/10.1111/ejh.13354DOI Listing
February 2020

Venetoclax with azacitidine targets refractory MDS but spares healthy hematopoiesis at tailored dose.

Exp Hematol Oncol 2019 16;8. Epub 2019 Apr 16.

Medical Department III for Hematology and Oncology, Klinikum rechts der Isar, Technische Universität München, Ismaninger Strasse 22, 81675 Munich, Germany.

Patients with Myelodysplastic Syndromes (MDS) and secondary Acute Myeloid Leukemia (sAML) have a very poor prognosis after failure of hypomethylating agents (HMA). Stem cell transplantation is the only effective salvage therapy, for which only a limited number of patients are eligible due to age and comorbidity. Combination therapy of venetoclax and azacitidine (5-AZA) seems to be a promising approach in myeloid malignancies, but data from patients with HMA failure are lacking. Furthermore, a considerable concern of combination regimens in elderly AML and MDS patients is the toxicity on the remaining healthy hematopoiesis. Here, we report in vitro data showing the impact of venetoclax and 5-AZA, alone or in combination, in a larger cohort of MDS/sAML patients (n = 21), even after HMA failure (n = 13). We especially focused on the effects on healthy hematopoiesis and the impact on colony forming capacity as a parameter for long-term effects. To the best of our knowledge, we show for the first time that venetoclax in combination with capped dose of 5-AZA targets cell malignancies, while sparing healthy hematopoiesis.
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http://dx.doi.org/10.1186/s40164-019-0133-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6469098PMC
April 2019

Circulating cKIT and PDGFRA DNA indicates disease activity in Gastrointestinal Stromal Tumor (GIST).

Int J Cancer 2019 10 29;145(8):2292-2303. Epub 2019 Apr 29.

Department of Hematology, Oncology and Stem Cell Transplantation, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany.

This prospective trial aimed to investigate whether tumor-specific cKIT and PDGFRA mutations can be detected and quantified in circulating tumor (ct)DNA in patients with active GIST, and whether detection indicates disease activity. We included 25 patients with active disease and cKIT or PDGFRA mutations detected in tissue. Mutant ctDNA was detected in the peripheral blood plasma using allele-specific ligation (L-)PCR and droplet digital (d)PCR. CtDNA harboring tumor-specific cKIT or PDGFRA mutations was detected at least once in 16 out of 25 patients using L-PCR (64%) and in 20 out of 25 patients with dPCR (80%). Using dPCR, the absolute numbers of ctDNA fragments (DNA copies/ml) and the mutant allele frequency (MAF; in percent of wild-type control) strongly correlated with tumor size expressed as RECIST1.1 sum of diameter (SOD) in mm (ρ = 0.3719 and 0.408, respectively, p < 0.0001) and response status (ρ = 0.3939 and 0.392, respectively, p < 0.0001 and p < 0.001). Specificity of dPCR for detection of progression was 79.2% with a sensitivity of 55.2% and dPCR discriminated CR from active disease with a specificity of 96% and s sensitivity of 44.7%. With L-PCR, correlations of MAF with tumor size and response status were less prominent. Serial ctDNA measurement reflected individual disease courses over time. Targeted panel sequencing of four patients detected additional driver mutations in all cases and secondary resistance mutations in two cases. Thus, ctDNA indicates disease activity in patients with GIST and should be incorporated as companion biomarker in future prospective trials.
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http://dx.doi.org/10.1002/ijc.32282DOI Listing
October 2019

Cancer clinical trials - Survey evaluating patient participation and acceptance in a university-based Comprehensive Cancer Center (CCC).

Clin Transl Radiat Oncol 2018 Nov 4;13:44-49. Epub 2018 Oct 4.

Department of Radiation Oncology, Technical University of Munich (TUM), Ismaninger Straße 22, Munich, Germany.

Introduction: Prospective clinical trials are essential to translate new therapy concepts or rather any scientific development into the medical routine. Besides a sophisticated trial protocol, the success of clinical trials depends on patient recruitment and participation. Patient recruitment remains a challenge and depends on several factors. To get a current picture of the patients' attitude, we conducted the present survey.

Methods: We designed a survey with seven questions, which was given to all oncological patients treated within a timeframe of three months between Mai and July 2017. Participation was voluntary and anonymous. The questionnaire mainly inquires patients' participation in clinical trials in a university-based setting, their attitude towards clinical trials regarding risks and benefits, and their source of information in this context.

Results: 771 patients (1:1 male/female) participated with a median age of 61 years (range 18-91 years) with a response rate of 71.5%. Of all, 17.8% (137/771) were participating in a clinical trial. The most mentioned reason was to serve medical progress and cancer research. Out of the patients not currently participating in a trial, 79 (12.7%, 79/623) refusers named the following main reasons: extensive travel time to the clinic, no therapeutic advantage, and too time-consuming. Out of the patients not offered to take part in a trial, 265 (51.0%, 265/520) would participate if offered. Of all patients, 8.3% (64/771) used the clinics' homepage as a source of information, of those 79.7% (51/64) were satisfied with its content. To enhance patient recruitment strategies, we asked how patients wish to be informed about possible trials: More than half (52.0%) of the questioned patients preferred an individual medical consultation with their physician.We further analyzed the trial participation depending on age, gender, unit, and tumor entity. We could show a significant influence of age (p < 0.001) but not for gender (p = 0.724). The trial participation was also significantly associated with the treating unit (p < 0.001) and tumor entity (p = 0.001).

Conclusion: Patients are willing to participate in clinical trials. Better information strategies need to be implemented. Physicians need to be aware of running trials within their department and must counseling counsel patients effectively to improve recruitment. Trial concepts should keep in mind patients' needs including an adequate number of appointments, positive risk-benefit profiles, and information material.
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http://dx.doi.org/10.1016/j.ctro.2018.10.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6192009PMC
November 2018

Notch2 controls non-autonomous Wnt-signalling in chronic lymphocytic leukaemia.

Nat Commun 2018 09 21;9(1):3839. Epub 2018 Sep 21.

Wellcome Trust/ MRC Cambridge Stem Cell Institute & Department of Haematology, University of Cambridge, Cambridge, CB2 0AH, UK.

The Wnt signalling pathway, one of the core de-regulated pathways in chronic lymphocytic leukaemia (CLL), is activated in only a subset of patients through somatic mutations. Here we describe alternative, microenvironment-dependent mechanisms of Wnt activation in malignant B cells. We show that tumour cells specifically induce Notch2 activity in mesenchymal stromal cells (MSCs) required for the transcription of the complement factor C1q. MSC-derived C1q in turn inhibits Gsk3-β mediated degradation of β-catenin in CLL cells. Additionally, stromal Notch2 activity regulates N-cadherin expression in CLL cells, which interacts with and further stabilises β-catenin. Together, these stroma Notch2-dependent mechanisms induce strong activation of canonical Wnt signalling in CLL cells. Pharmacological inhibition of the Wnt pathway impairs microenvironment-mediated survival of tumour cells. Similarly, inhibition of Notch signalling diminishes survival of stroma-protected CLL cells in vitro and disease engraftment in vivo. Notch2 activation in the microenvironment is a pre-requisite for the activation of canonical Wnt signalling in tumour cells.
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http://dx.doi.org/10.1038/s41467-018-06069-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6155045PMC
September 2018

Evaluation of the new continuous mononuclear cell collection protocol versus an older version on two different apheresis machines.

Transfusion 2018 07 6;58(7):1772-1780. Epub 2018 May 6.

3rd Medical Department, Hematology and Oncology, Klinikum rechts der Isar, Technische Universität München, München, Germany.

Background: Cell separators are routinely used to collect CD34 blood stem cells in the context of customized stem cell transplantation procedures. The Spectra Optia (Terumo BCT) is a novel development of the precursor instrument, the Cobe Spectra (Terumo BCT).

Study Design And Methods: In this report, 146 autologous and 42 allogeneic donors undergoing apheresis on the Cobe Spectra using the mononuclear cell (MNC) program 4.7 or on the Spectra Optia using the new continuous mononuclear cell (cMNC) program 11.2 are compared.

Results: Viability of cells and collection efficacy within the apheresis products was comparable for autologous and allogeneic products collected with the MNC or cMNC method. However, we found a reduced duration of the apheresis procedure and lower hematocrit within the apheresis products when using the cMNC in autologous and allogeneic donors. Moreover, allogeneic donors collected substantially more CD34 cells per kilogram of body weight when using the cMNC method. Differences in platelets before and after apheresis were substantially smaller in this cohort when compared to the cohort collected with the MNC method. Neutrophil and platelet engraftment after autologous or allogeneic transplantation with a product collected with the MNC procedure was comparable to a transplantation with a product processed according to the cMNC method.

Conclusion: Comparison of the MNC (Cobe Spectra) and the cMNC (Spectra Optia) methods demonstrated an equal performance and outcome. However, advantages were present using the cMNC method with respect to apheresis duration and hematocrit within the apheresis product (autologous/allogeneic donors) and numbers of CD34 cells collected, especially in allogeneic donors.
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http://dx.doi.org/10.1111/trf.14644DOI Listing
July 2018

Selective inhibition of BCL-2 is a promising target in patients with high-risk myelodysplastic syndromes and adverse mutational profile.

Oncotarget 2018 Apr 3;9(25):17270-17281. Epub 2018 Apr 3.

Medizinische Klinik für Hämatologie und Internistische Onkologie, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.

Somatic mutations in genes such as , , or adversely affect the outcome of patients with myelodysplastic syndromes (MDS). Since selective BCL-2 inhibition is a promising treatment strategy in hematologic malignancies, we tested the therapeutic impact of ABT-199 on MDS patient samples bearing an adverse mutational profile. By gene expression, we found that the level of pro-apoptotic BIM significantly decreased during MDS disease progression in line with an acquired resistance to cell death. Supporting the potential for ABT-199 treatment in MDS, high-risk MDS patient samples specifically underwent cell death in response to ABT-199 even when harbouring mutations in , , or . ABT-199 effectively targeted the stem- and progenitor compartment in advanced MDS harbouring mutations in , , or and even proved effective in patients harbouring more than one of the defined high-risk mutations. Moreover, we utilized the protein abundance of BCL-2 family members in primary patient samples using flow cytometry as a biomarker to predict ABT-199 treatment response. Our data demonstrate that ABT-199 effectively induces apoptosis in progenitors of high-risk MDS/sAML despite the presence of adverse genetic mutations supporting the notion that pro-apoptotic intervention will hold broad therapeutic potential in high-risk MDS patients with poor prognosis.
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http://dx.doi.org/10.18632/oncotarget.24775DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5915115PMC
April 2018

Outcome of a Salvage Third Autologous Stem Cell Transplantation in Multiple Myeloma.

Biol Blood Marrow Transplant 2018 07 3;24(7):1372-1378. Epub 2018 Feb 3.

Department of Hematology, Eppendorf University Hospital, Hamburg, Germany.

To evaluate the outcomes of salvage third autologous stem cell transplantation (ASCT) in patients with relapsed multiple myeloma. We analyzed 570 patients who had undergone a third ASCT between 1997 and 2010 (European Society for Blood and Marrow Transplantation data), of whom 482 patients underwent tandem ASCT and a third ASCT at first relapse (AARA group) and 88 patients underwent an upfront ASCT with second and third transplantations after subsequent relapses (ARARA group). With a median follow-up after salvage third ASCT of 61 months in the AARA group and 48 months in the ARARA group, the day +100 nonrelapse mortality in the 2 groups was 4% and 7%, the incidence of second primary malignancy was 6% and 7%, the median progression-free survival was 13 and 8 months, and median overall survival (OS) was 33 and 15 months. In the AARA group, according to the relapse-free interval (RFI) from the second ASCT, the median OS after the third ASCT was 17 months if the RFI was <18 months, 37 months if the RFI was between 18 and 36 months, and 64 months if the RFI was ≥36 months (P < .001). In the ARARA group, the median OS after the third ASCT was 7 months if the RFI was <6 months, 13 months if the RFI was between 6 and 18 months, and 27 months if the RFI was ≥18 months (P < .001). In a multivariate analysis of the AARA group, the favorable prognostic factor was an RFI after second ASCT of ≥18 months. Progressive disease and a Karnofsky Performance Status score of <70 at third ASCT were unfavorable factors. A salvage third ASCT is of value for patients with relapsed myeloma, particularly for those with a long duration of response and chemosensitive disease at the time of transplantation.
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http://dx.doi.org/10.1016/j.bbmt.2018.01.035DOI Listing
July 2018

Azacitidine combined with the selective FLT3 kinase inhibitor crenolanib disrupts stromal protection and inhibits expansion of residual leukemia-initiating cells in -ITD AML with concurrent epigenetic mutations.

Oncotarget 2017 Dec 16;8(65):108738-108759. Epub 2017 Oct 16.

Department of Medicine III, Klinikum rechts der Isar, Technische Universität München (TUM), Munich, Germany.

Effectively targeting leukemia-initiating cells (LIC) in -ITD-mutated acute myeloid leukemia (AML) is crucial for cure. Tyrosine kinase inhibitors (TKI) have limited impact as single agents, failing to eradicate LIC in the bone marrow. Using primary AML samples and a patient-derived xenograft model, we investigated whether combining the FLT3-selective TKI crenolanib with the hypomethylating agent azacitidine (AZA) eliminates -ITD LIC and whether efficacy of this combination depends on co-existing mutations. Using multiparameter flow cytometry, we show -ITD occurs within the most primitive Lin/CD33/CD45/CD34CD38 LIC compartment. Crenolanib alone could not target -ITD LIC in contact with niche cells while addition of AZA overcame stromal protection resulting in dramatically reduced clonogenic capacity of LIC and severely impaired engraftment in NSG mice. Strikingly, -mutated samples harboring mutations were completely resistant to crenolanib whereas neither nor mutations influenced response. Conversely, primary AML LIC harboring either or mutations did not show increased sensitivity to AZA. In summary, resistance of -ITD LIC to TKI depends on co-existing epigenetic mutations. However, AZA + crenolanib effectively abrogates stromal protection and inhibits survival of -ITD LIC irrespective of mutations, providing evidence for this combination as a means to suppress residual LIC.
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http://dx.doi.org/10.18632/oncotarget.21877DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5752477PMC
December 2017

Dual Targeting of Acute Leukemia and Supporting Niche by CXCR4-Directed Theranostics.

Theranostics 2018 1;8(2):369-383. Epub 2018 Jan 1.

Internal Medicine III, Hematology and Medical Oncology, Technische Universität München, Munich, Germany.

C-X-C chemokine receptor 4 (CXCR4) is a transmembrane receptor with pivotal roles in cell homing and hematopoiesis. CXCR4 is also involved in survival, proliferation and dissemination of cancer, including acute lymphoblastic and myeloid leukemia (ALL, AML). Relapsed/refractory ALL and AML are frequently resistant to conventional therapy and novel highly active strategies are urgently needed to overcome resistance. We used patient-derived (PDX) and cell line-based xenograft mouse models of ALL and AML to evaluate the efficacy and toxicity of a CXCR4-targeted endoradiotherapy (ERT) theranostic approach. The positron emission tomography (PET) tracer Ga-Pentixafor enabled visualization of CXCR4 positive leukemic burden. In xenografts, CXCR4-directed ERT with Lu-Pentixather distributed to leukemia harboring organs and resulted in efficient reduction of leukemia. Despite a substantial cross-fire effect to the leukemia microenvironment, mesenchymal stem cells (MSCs) subjected to ERT were viable and capable of supporting the growth and differentiation of non-targeted normal hematopoietic cells . Finally, three patients with refractory AML after first allogeneic hematopoietic stem cell transplantation (alloSCT) underwent CXCR4-directed ERT resulting in leukemia clearance, second alloSCT, and successful hematopoietic engraftment. Targeting CXCR4 with ERT is feasible and provides a highly efficient means to reduce refractory acute leukemia for subsequent cellular therapies. Prospective clinical trials testing the incorporation of CXCR4 targeting into conditioning regimens for alloSCT are highly warranted.
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http://dx.doi.org/10.7150/thno.21397DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5743554PMC
December 2018

A20 Restrains Thymic Regulatory T Cell Development.

J Immunol 2017 10 25;199(7):2356-2365. Epub 2017 Aug 25.

Klinik und Poliklinik für Innere Medizin III, Klinikum rechts der Isar, Technische Universität, 81675 Munich, Germany;

Maintaining immune tolerance requires the production of Foxp3-expressing regulatory T (T) cells in the thymus. Activation of NF-κB transcription factors is critically required for T cell development, partly via initiating Foxp3 expression. NF-κB activation is controlled by a negative feedback regulation through the ubiquitin editing enzyme A20, which reduces proinflammatory signaling in myeloid cells and B cells. In naive CD4 T cells, A20 prevents kinase RIPK3-dependent necroptosis. Using mice deficient for A20 in T lineage cells, we show that thymic and peripheral T cell compartments are quantitatively enlarged because of a cell-intrinsic developmental advantage of A20-deficient thymic T differentiation. A20-deficient thymic T cells exhibit reduced dependence on IL-2 but unchanged rates of proliferation and apoptosis. Activation of the NF-κB transcription factor RelA was enhanced, whereas nuclear translocation of c-Rel was decreased in A20-deficient thymic T cells. Furthermore, we found that the increase in T cells in T cell-specific A20-deficient mice was already observed in CD4 single-positive CD25 GITR Foxp3 thymic T cell progenitors. T cell precursors expressed high levels of the tumor necrosis factor receptor superfamily molecule GITR, whose stimulation is closely linked to thymic T cell development. A20-deficient T cells efficiently suppressed effector T cell-mediated graft-versus-host disease after allogeneic hematopoietic stem cell transplantation, suggesting normal suppressive function. Holding thymic production of natural T cells in check, A20 thus integrates T cell activity and increased effector T cell survival into an efficient CD4 T cell response.
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http://dx.doi.org/10.4049/jimmunol.1602102DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5617121PMC
October 2017

A20 deletion in T cells modulates acute graft-versus-host disease in mice.

Eur J Immunol 2017 11 15;47(11):1982-1988. Epub 2017 Sep 15.

Klinik und Poliklinik für Innere Medizin III, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.

The NF-κB regulator A20 limits inflammation by providing negative feedback in myeloid cells and B cells. Functional lack of A20 has been linked to several inflammatory and autoimmune diseases. To define how A20 affects the functionality of T effector cells in a highly inflammatory environment, we performed conventional allogeneic hematopoietic stem cell transplantation (allo-HSCT) with A20-deficient CD4 and CD8 donor T cells in mice. Severity and mortality of graft-versus-host disease (GVHD) after allo-HSCT was drastically reduced in recipients transplanted with conventional doses of A20-deficient T cells. Consistently, we found that the A20-deficient donor T-cell compartment was strongly diminished at various timepoints after allo-HSCT. However, proportionally more A20-deficient donor T cells produced IFN-γ and systemic inflammation was elevated early after allo-HSCT. Consequently, increasing the dose of transplanted A20-deficient T cells reversed the original phenotype and resulted in enhanced GVHD mortality compared to recipients that received A20 T cells. Still, A20-deficient T cells, activated either through T cell receptor-dependent or -independent mechanisms, were less viable than control A20 T cells, highlighting that A20 balances both, T-cell activation and survival. Thus, our findings suggest that targeting A20 in T cells may allow to modulate T-cell-mediated inflammatory diseases like GVHD.
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http://dx.doi.org/10.1002/eji.201646911DOI Listing
November 2017

In-depth Characterization of a TCR-specific Tracer for Sensitive Detection of Tumor-directed Transgenic T Cells by Immuno-PET.

Theranostics 2017 15;7(9):2402-2416. Epub 2017 Jun 15.

Department of Nuclear Medicine, Klinikum rechts der Isar, Technische Universität München, Germany.

A number of different technologies have been developed to monitor the distribution of gene-modified T cells used in immunotherapy. Nevertheless, in-depth characterization of novel approaches with respect to sensitivity and clinical applicability are so far missing. We have previously described a novel method to track engineered human T cells in tumors using Zr-Df-aTCRmu-F(ab') targeting the murinized part of the TCR beta domain (TCRmu) of a transgenic TCR. Here, we performed an in-depth characterization of the tracer in terms of antigen affinity, immunoreactivity, influence on T-cell functionality and stability and . Of particular interest, we have developed diverse experimental settings to quantify TCR-transgenic T cells . Local application of Zr-Df-aTCRmu-F(ab')-labeled T cells in a spot-assay revealed signal detection down to approximately 1.8x10 cells. In a more clinically relevant model, NSG mice were intravenously injected with different numbers of transgenic T cells, followed by injection of the Zr-Df-aTCRmu-F(ab') tracer, PET/CT imaging and subsequent T-cell quantification in the tumor. Using this setting, we defined a comparable detection limit of 1.0x10 T cells. PET signals correlated well to total numbers of transgenic T cells detected independently of the engraftment rates observed in different individual experiments. Thus, these findings confirm the high sensitivity of our novel PET/CT T-cell tracking method and provide critical information about the quantity of transgenic T cells in the tumor environment suggesting our technology being highly suitable for further clinical translation.
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http://dx.doi.org/10.7150/thno.17994DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5525745PMC
March 2018

Mobile Health in Oncology: A Patient Survey About App-Assisted Cancer Care.

JMIR Mhealth Uhealth 2017 Jun 14;5(6):e81. Epub 2017 Jun 14.

Klinikum rechts der Isar, Department of Radiation Oncology, Technical University of Munich (TUM), Munich, Germany.

Background: In the last decade, the health care sector has been enriched by numerous innovations such as apps and connected devices that assist users in weight reduction and diabetes management. However, only a few native apps in the oncological context exist, which support patients during treatment and aftercare.

Objective: The objective of this study was to analyze patients' acceptance regarding app use and to investigate the functions of an oncological app that are most required, and the primary reasons for patients to refuse app-assisted cancer care.

Methods: We designed and conducted a survey with 23 questions, inquiring patients about their technical knowledge and equipment, as well as the possible advantages and disadvantages, data transfer, and general functionality of an app.

Results: A total of 375 patients participated; the participation rate was 60.7% (375/618). Gender distribution was about 3:4 (female:male) with a median age of 59 years (range 18-92 years). Whereas 69.6% (261/375) of patients used mobile devices, 16.3% (61/375) did not own one, and 9.1% (34/375) only used a personal computer (PC). About half of the patients rated their usability skills as very good and good (18.9% 71/375; 35.2% 132/375), 23.5% (88/375) described their skills as intermediate, and 14.4% (54/375) as bad. Of all patients, 182 (48.5%, 182/375) were willing to send data to their treating clinic via an app, that is, to a server (61.0% 111/182) or as email (33.5%, 61/182). About two-thirds (68.7%, 125/182) believed that additional and regularly sent data would be an ideal complement to the standard follow-up procedure. Additionally, 86.8% (158/182) wished to be contacted by a physician when entered data showed irregularities. Because of lack of skills (34.4%, 56/163), concerns about the use of data (35.0%, 57/163), lack of capable devices (25.8%, 42/163), and the wish for personal contact with the treating physician (47.2%, 77/163), a total of 163 (43.5%, 163/375) patients refused to use an app. Pearson correlation showed a significant but mild relationship between age and app use (P=.03, r=-.12), favoring younger age; male gender correlated as well (P=.04; r=-.11).

Conclusions: The results show that the introduction of mobile apps needs to follow different strategies depending on the patients' attitude. Age and gender seem to be the strongest predictive factors. For oncology patients, our survey showed that about half of the patients were willing to send data via an app supporting their treatment. In the future, clinical data such as quality of life and treatment satisfaction recorded by mobile health (mHealth) devices could be used to evaluate and improve therapy workflow. Furthermore, apps could support classical visits, document adverse effects, and remind patients of treatment dates or drug intake.
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http://dx.doi.org/10.2196/mhealth.7689DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5489709PMC
June 2017

RIG-I/MAVS and STING signaling promote gut integrity during irradiation- and immune-mediated tissue injury.

Sci Transl Med 2017 04;9(386)

III. Medizinische Klinik, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.

The molecular pathways that regulate the tissue repair function of type I interferon (IFN-I) during acute tissue damage are poorly understood. We describe a protective role for IFN-I and the RIG-I/MAVS signaling pathway during acute tissue damage in mice. Mice lacking mitochondrial antiviral-signaling protein (MAVS) were more sensitive to total body irradiation- and chemotherapy-induced intestinal barrier damage. These mice developed worse graft-versus-host disease (GVHD) in a preclinical model of allogeneic hematopoietic stem cell transplantation (allo-HSCT) than did wild-type mice. This phenotype was not associated with changes in the intestinal microbiota but was associated with reduced gut epithelial integrity. Conversely, targeted activation of the RIG-I pathway during tissue injury promoted gut barrier integrity and reduced GVHD. Recombinant IFN-I or IFN-I expression induced by RIG-I promoted growth of intestinal organoids in vitro and production of the antimicrobial peptide regenerating islet-derived protein 3 γ (RegIIIγ). Our findings were not confined to RIG-I/MAVS signaling because targeted engagement of the STING (stimulator of interferon genes) pathway also protected gut barrier function and reduced GVHD. Consistent with this, STING-deficient mice suffered worse GVHD after allo-HSCT than did wild-type mice. Overall, our data suggest that activation of either RIG-I/MAVS or STING pathways during acute intestinal tissue injury in mice resulted in IFN-I signaling that maintained gut epithelial barrier integrity and reduced GVHD severity. Targeting these pathways may help to prevent acute intestinal injury and GVHD during allogeneic transplantation.
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http://dx.doi.org/10.1126/scitranslmed.aag2513DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5604790PMC
April 2017

Card9 controls Dectin-1-induced T-cell cytotoxicity and tumor growth in mice.

Eur J Immunol 2017 05 10;47(5):872-879. Epub 2017 Apr 10.

Institut für Klinische Chemie und Pathobiochemie, Klinikum rechts der Isar, Technische Universität, Munich, Germany.

Activation of the C-type lectin receptor Dectin-1 by β-glucans triggers multiple signals within DCs that result in activation of innate immunity. While these mechanisms can potently prime CD8 cytotoxic T-cell (CTL) responses without additional adjuvants, the Dectin-1 effector pathways that control CTL induction remain unclear. Here we demonstrate that Dectin-1-induced CTL cross-priming in mice does not require inflammasome activation but strictly depends on the adapter protein Card9 in vitro. In vivo, Dectin-1-mediated Card9 activation after vaccination drives both expansion and activation of Ag-specific CTLs, resulting in long-lasting CTL responses that are sufficient to protect mice from tumor challenge. This Dectin-1-induced antitumor immune response was independent of NK cell function and completely abrogated in Card9-deficient mice. Thus, our results demonstrate that Dectin-1-triggered Card9 signaling but not inflammasome activation can potently cross-prime Ag-specific CTLs, suggesting that this pathway would be a candidate for immunotherapy and vaccine development.
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http://dx.doi.org/10.1002/eji.201646775DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5434796PMC
May 2017

Roquin Paralogs Differentially Regulate Functional NKT Cell Subsets.

J Immunol 2017 04 10;198(7):2747-2759. Epub 2017 Feb 10.

III. Medizinische Klinik für Hämatologie und Onkologie, Klinikum Rechts der Isar, Technische Universität München, 81675 Munich, Germany;

NKT cells represent a small subset of glycolipid-recognizing T cells that are heavily implicated in human allergic, autoimmune, and malignant diseases. In the thymus, precursor cells recognize self-glycolipids by virtue of their semi-invariant TCR, which triggers NKT cell lineage commitment and maturation. During their development, NKT cells are polarized into the NKT1, NKT2, and NKT17 subsets, defined through their cytokine-secretion patterns and the expression of key transcription factors. However, we have largely ignored how the differentiation into the NKT cell subsets is regulated. In this article, we describe the mRNA-binding Roquin-1 and -2 proteins as central regulators of murine NKT cell fate decisions. In the thymus, T cell-specific ablation of the Roquin paralogs leads to a dramatic expansion of NKT17 cells, whereas peripheral mature NKT cells are essentially absent. Roquin-1/2-deficient NKT17 cells show exaggerated lineage-specific expression of nearly all NKT17-defining proteins tested. We show through mixed bone marrow chimera experiments that NKT17 polarization is mediated through cell-intrinsic mechanisms early during NKT cell development. In contrast, the loss of peripheral NKT cells is due to cell-extrinsic factors. Surprisingly, Roquin paralog-deficient NKT cells are, in striking contrast to conventional T cells, compromised in their ability to secrete cytokines. Altogether, we show that Roquin paralogs regulate the development and function of NKT cell subsets in the thymus and periphery.
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http://dx.doi.org/10.4049/jimmunol.1601732DOI Listing
April 2017

Niche WNT5A regulates the actin cytoskeleton during regeneration of hematopoietic stem cells.

J Exp Med 2017 01 20;214(1):165-181. Epub 2016 Dec 20.

Third Department of Internal Medicine, Klinikum rechts der Isar, Technische Universität München, 81675 Munich, Germany

Here, we show that the Wnt5a-haploinsufficient niche regenerates dysfunctional HSCs, which do not successfully engraft in secondary recipients. RNA sequencing of the regenerated donor Lin SCA-1 KIT (LSK) cells shows dysregulated expression of ZEB1-associated genes involved in the small GTPase-dependent actin polymerization pathway. Misexpression of DOCK2, WAVE2, and activation of CDC42 results in apolar F-actin localization, leading to defects in adhesion, migration and homing of HSCs regenerated in a Wnt5a-haploinsufficient microenvironment. Moreover, these cells show increased differentiation in vitro, with rapid loss of HSC-enriched LSK cells. Our study further shows that the Wnt5a-haploinsufficient environment similarly affects BCR-ABL leukemia-initiating cells, which fail to generate leukemia in 42% of the studied recipients, or to transfer leukemia to secondary hosts. Thus, we show that WNT5A in the bone marrow niche is required to regenerate HSCs and leukemic cells with functional ability to rearrange the actin cytoskeleton and engraft successfully.
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http://dx.doi.org/10.1084/jem.20151414DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5206491PMC
January 2017

Direct identification of clinically relevant neoepitopes presented on native human melanoma tissue by mass spectrometry.

Nat Commun 2016 11 21;7:13404. Epub 2016 Nov 21.

IIIrd Medical Department, Klinikum rechts der Isar, Technische Universität München, Ismaningerstr. 22, Munich 81675, Germany.

Although mutations may represent attractive targets for immunotherapy, direct identification of mutated peptide ligands isolated from human leucocyte antigens (HLA) on the surface of native tumour tissue has so far not been successful. Using advanced mass spectrometry (MS) analysis, we survey the melanoma-associated immunopeptidome to a depth of 95,500 patient-presented peptides. We thereby discover a large spectrum of attractive target antigen candidates including cancer testis antigens and phosphopeptides. Most importantly, we identify peptide ligands presented on native tumour tissue samples harbouring somatic mutations. Four of eleven mutated ligands prove to be immunogenic by neoantigen-specific T-cell responses. Moreover, tumour-reactive T cells with specificity for selected neoantigens identified by MS are detected in the patient's tumour and peripheral blood. We conclude that direct identification of mutated peptide ligands from primary tumour material by MS is possible and yields true neoepitopes with high relevance for immunotherapeutic strategies in cancer.
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http://dx.doi.org/10.1038/ncomms13404DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5121339PMC
November 2016

Patients' outcome after rescue plerixafor administration for autologous stem cell mobilization: a single-center retrospective analysis.

Transfusion 2017 01 18;57(1):115-121. Epub 2016 Nov 18.

III. Medical Department, Hematology and Oncology, Klinikum rechts der Isar, Technische Universität München, München, Germany.

Background: Plerixafor is predominantly used for patients mobilizing inadequate stem cell numbers for autologous transplantation after stimulation with granulocyte-colony-stimulating factor (G-CSF).

Study Design And Methods: We here report on 300 patients undergoing stem cell mobilization with G-CSF, among them 36 poor mobilizers (CD34+ cell counts < 50 × 10 /L blood) receiving G-CSF alone and 49 receiving G-CSF in combination with plerixafor for rescue intervention. Mobilization efficacy and short-time outcome after autologous stem cell transplantation were analyzed and compared in the respective subgroups.

Results: Out of 49 patients treated with plerixafor and G-CSF, 46 (94%) collected sufficient hematopoietic stem cell numbers although the number was clearly inferior in poor mobilizers. Compared to good mobilizers, viability of CD34+ cells analyzed after collection was slightly reduced in poor mobilizers independent of the application of plerixafor. A total of 232 patients underwent autologous stem cell transplantation, among them 26 poor mobilizers who received only G-CSF and 31 patients who received G-CSF in combination with plerixafor. Time until neutrophil engraftment was in median 1 day later in poor mobilizers irrespective of the application of plerixafor. Platelet engraftment was in median 2 days delayed in patients mobilized with G-CSF and plerixafor compared to 1 day in poor mobilizers treated with G-CSF only. Frequency of detected CD38+ CD138+ CD45- CD56+ plasma cells in the apheresis products of myeloma patients was comparable for all groups.

Conclusion: Our data demonstrate that plerixafor is highly effective as rescue measurement after mobilization failure with G-CSF alone and short-term clinical outcome after stem cell transplantation is comparable.
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http://dx.doi.org/10.1111/trf.13883DOI Listing
January 2017

Use of Complementary and Alternative Medicine (CAM) as Part of the Oncological Treatment: Survey about Patients' Attitude towards CAM in a University-Based Oncology Center in Germany.

PLoS One 2016 3;11(11):e0165801. Epub 2016 Nov 3.

Department of Radiation Oncology, Technical University of Munich (TUM), Ismaninger Straße 22, Munich, Germany.

Introduction: To understand if and which patients would be open-minded to Complementary and Alternative Medicine (CAM) use parallel to their oncological treatment. Moreover, we sought to determine which methods are most accepted and which are the primary motivators to use CAM.

Methods: We developed and anonymously conducted a questionnaire for patients in the oncology center (TU Munich). Questions focus on different CAM methods, previous experiences, and willingness to apply or use CAM when offered in a university-based setting.

Results: A total of 171 of 376 patients (37.4% women, 62.0% men, 0.6% unknown) participated. This corresponds to a return rate of 45%. Median age was 64 years (17-87 years). Of all participants, 15.2% used CAM during their oncological therapy; 32.7% have used it in the past. The majority (81.9%) was not using CAM during therapy; 55.5% have not used CAM in the past respectively. The analysis revealed a significant correlation between education and CAM use during therapy (r = 0.18; p = 0.02), and CAM use in the past (r = 0.17; p = 0.04). Of all patients using CAM during therapy, favored methods were food supplements (42.3%), vitamins/minerals (42.3%), massage (34.6%). Motivations are especially the reduction of side effect and stress, the positive effect of certain CAM-treatments on the immune system and tumor therapy. Results showed no difference between women and men. Most patients not having had any experience with CAM complain about the deficiency of information by their treating oncologist (31.4%) as well as missing treatment possibilities (54.3%).

Conclusion: Since many patients believe in study results demonstrating the efficacy of CAM, it stresses our task to develop innovative study protocols to investigate the outcomes of certain CAM on symptom reduction or other endpoints. Thus, prospective trials and innovative evidence-based treatment concepts to include CAM into high-end oncology is what patients demand and what a modern oncology center should offer.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0165801PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5094772PMC
July 2017

RIPK3 Restricts Myeloid Leukemogenesis by Promoting Cell Death and Differentiation of Leukemia Initiating Cells.

Cancer Cell 2016 07;30(1):75-91

III. Medical Department for Hematology and Oncology, Klinikum rechts der Isar, Technische Universität München, 81675 München, Germany; German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany. Electronic address:

Since acute myeloid leukemia (AML) is characterized by the blockade of hematopoietic differentiation and cell death, we interrogated RIPK3 signaling in AML development. Genetic loss of Ripk3 converted murine FLT3-ITD-driven myeloproliferation into an overt AML by enhancing the accumulation of leukemia-initiating cells (LIC). Failed inflammasome activation and cell death mediated by tumor necrosis factor receptor caused this accumulation of LIC exemplified by accelerated leukemia onset in Il1r1(-/-), Pycard(-/-), and Tnfr1/2(-/-) mice. RIPK3 signaling was partly mediated by mixed lineage kinase domain-like. This link between suppression of RIPK3, failed interleukin-1β release, and blocked cell death was supported by significantly reduced RIPK3 in primary AML patient cohorts. Our data identify RIPK3 and the inflammasome as key tumor suppressors in AML.
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http://dx.doi.org/10.1016/j.ccell.2016.06.002DOI Listing
July 2016

Immuno-PET Imaging of Engineered Human T Cells in Tumors.

Cancer Res 2016 07 28;76(14):4113-23. Epub 2016 Jun 28.

Medizinische Klinik III, Klinikum rechts der Isar, Technische Universität München, Munich, Germany. German Cancer Consortium (DKTK), Munich, Germany. Clinical Cooperation Group Antigen Specific T-Cell Therapy, Helmholtz Zentrum München, Munich, Germany.

Sensitive in vivo imaging technologies applicable to the clinical setting are still lacking for adoptive T-cell-based immunotherapies, an important gap to fill if mechanisms of tumor rejection or escape are to be understood. Here, we propose a highly sensitive imaging technology to track human TCR-transgenic T cells in vivo by directly targeting the murinized constant TCR beta domain (TCRmu) with a zirconium-89 ((89)Zr)-labeled anti-TCRmu-F(ab')2 fragment. Binding of the labeled or unlabeled F(ab')2 fragment did not impair functionality of transgenic T cells in vitro and in vivo Using a murine xenograft model of human myeloid sarcoma, we monitored by Immuno-PET imaging human central memory T cells (TCM), which were transgenic for a myeloid peroxidase (MPO)-specific TCR. Diverse T-cell distribution patterns were detected by PET/CT imaging, depending on the tumor size and rejection phase. Results were confirmed by IHC and semiquantitative evaluation of T-cell infiltration within the tumor corresponding to the PET/CT images. Overall, these findings offer a preclinical proof of concept for an imaging approach that is readily tractable for clinical translation. Cancer Res; 76(14); 4113-23. ©2016 AACR.
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http://dx.doi.org/10.1158/0008-5472.CAN-15-2784DOI Listing
July 2016

USP9X stabilizes XIAP to regulate mitotic cell death and chemoresistance in aggressive B-cell lymphoma.

EMBO Mol Med 2016 08 1;8(8):851-62. Epub 2016 Aug 1.

Department of Medicine III, Klinikum Rechts der Isar, Technische Universität München, München, Germany German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany

The mitotic spindle assembly checkpoint (SAC) maintains genome stability and marks an important target for antineoplastic therapies. However, it has remained unclear how cells execute cell fate decisions under conditions of SAC-induced mitotic arrest. Here, we identify USP9X as the mitotic deubiquitinase of the X-linked inhibitor of apoptosis protein (XIAP) and demonstrate that deubiquitylation and stabilization of XIAP by USP9X lead to increased resistance toward mitotic spindle poisons. We find that primary human aggressive B-cell lymphoma samples exhibit high USP9X expression that correlate with XIAP overexpression. We show that high USP9X/XIAP expression is associated with shorter event-free survival in patients treated with spindle poison-containing chemotherapy. Accordingly, aggressive B-cell lymphoma lines with USP9X and associated XIAP overexpression exhibit increased chemoresistance, reversed by specific inhibition of either USP9X or XIAP. Moreover, knockdown of USP9X or XIAP significantly delays lymphoma development and increases sensitivity to spindle poisons in a murine Eμ-Myc lymphoma model. Together, we specify the USP9X-XIAP axis as a regulator of the mitotic cell fate decision and propose that USP9X and XIAP are potential prognostic biomarkers and therapeutic targets in aggressive B-cell lymphoma.
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http://dx.doi.org/10.15252/emmm.201506047DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4967940PMC
August 2016

Loss of Sfrp2 in the Niche Amplifies Stress-Induced Cellular Responses, and Impairs the In Vivo Regeneration of the Hematopoietic Stem Cell Pool.

Stem Cells 2016 09 30;34(9):2381-92. Epub 2016 Jun 30.

3rd Department of Internal Medicine, Klinikum Rechts Der Isar, Technische Universität München, Munich, Germany.

Sfrp2 is overexpressed in stromal cells which maintain hematopoietic stem cells (HSCs) during in vitro culture. We here showed, that coculture of hematopoetic cells with stromal cells with reduced expression of Sfrp2 increases the number lineage-negative Kit(+) Sca-1(+) (LSK) and progenitor cells in vitro. The LSK cells from these cocultures showed activation of canonical Wnt signaling, higher levels of Ki-67, BrdU incorporation, and the number of γH2A.X positive foci. Total repopulating activity of these cultures was, however, diminished, indicating loss of HSC. To extend these in vitro data, we modelled stress in vivo, i.e., by aging, or 5-FU treatment in Sfrp2(-) (/) (-) mice, or replicative stress in regeneration of HSCs in Sfrp2(-) (/) (-) recipients. In all three in vivo stress situations, we noted an increase of LSK cells, characterized by increased levels of β-catenin and cyclin D1. In the transplantation experiments, the increase in LSK cells in primary recipients was subsequently associated with a progressive loss of HSCs in serial transplantations. Similar to the in vitro coculture stress, in vivo genotoxic stress in 5-FU-treated Sfrp2(-) (/) (-) mice increased cell cycle activity of LSK cells with higher levels of BrdU incorporation, increased expression of Ki-67, and canonical Wnt signaling. Importantly, as noted in vitro, increased cycling of LSKs in vivo was accompanied by a defective γH2A.X-dependent DNA damage response and depolarized localization of acetylated H4K16. Our experiments support the view that Sfrp2 expression in the niche is required to maintain the HSC pool by limiting stress-induced DNA damage and attenuating canonical Wnt-mediated HSC activation. Stem Cells 2016;34:2381-2392.
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http://dx.doi.org/10.1002/stem.2416DOI Listing
September 2016

Immunomodulatory drugs disrupt the cereblon-CD147-MCT1 axis to exert antitumor activity and teratogenicity.

Nat Med 2016 07 13;22(7):735-43. Epub 2016 Jun 13.

Department of Medicine III, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.

Immunomodulatory drugs (IMiDs), such as thalidomide and its derivatives lenalidomide and pomalidomide, are key treatment modalities for hematologic malignancies, particularly multiple myeloma (MM) and del(5q) myelodysplastic syndrome (MDS). Cereblon (CRBN), a substrate receptor of the CRL4 ubiquitin ligase complex, is the primary target by which IMiDs mediate anticancer and teratogenic effects. Here we identify a ubiquitin-independent physiological chaperone-like function of CRBN that promotes maturation of the basigin (BSG; also known as CD147) and solute carrier family 16 member 1 (SLC16A1; also known as MCT1) proteins. This process allows for the formation and activation of the CD147-MCT1 transmembrane complex, which promotes various biological functions, including angiogenesis, proliferation, invasion and lactate export. We found that IMiDs outcompete CRBN for binding to CD147 and MCT1, leading to destabilization of the CD147-MCT1 complex. Accordingly, IMiD-sensitive MM cells lose CD147 and MCT1 expression after being exposed to IMiDs, whereas IMiD-resistant cells retain their expression. Furthermore, del(5q) MDS cells have elevated CD147 expression, which is attenuated after IMiD treatment. Finally, we show that BSG (CD147) knockdown phenocopies the teratogenic effects of thalidomide exposure in zebrafish. These findings provide a common mechanistic framework to explain both the teratogenic and pleiotropic antitumor effects of IMiDs.
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http://dx.doi.org/10.1038/nm.4128DOI Listing
July 2016

Targeted positron emission tomography imaging of CXCR4 expression in patients with acute myeloid leukemia.

Haematologica 2016 08 12;101(8):932-40. Epub 2016 May 12.

III Medical Department, Technische Universität München, Germany German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany

Acute myeloid leukemia originates from leukemia-initiating cells that reside in the protective bone marrow niche. CXCR4/CXCL12 interaction is crucially involved in recruitment and retention of leukemia-initiating cells within this niche. Various drugs targeting this pathway have entered clinical trials. To evaluate CXCR4 imaging in acute myeloid leukemia, we first tested CXCR4 expression in patient-derived primary blasts. Flow cytometry revealed that high blast counts in patients with acute myeloid leukemia correlate with high CXCR4 expression. The wide range of CXCR4 surface expression in patients was reflected in cell lines of acute myeloid leukemia. Next, we evaluated the CXCR4-specific peptide Pentixafor by positron emission tomography imaging in mice harboring CXCR4 positive and CXCR4 negative leukemia xenografts, and in 10 patients with active disease. [(68)Ga]Pentixafor-positron emission tomography showed specific measurable disease in murine CXCR4 positive xenografts, but not when CXCR4 was knocked out with CRISPR/Cas9 gene editing. Five of 10 patients showed tracer uptake correlating well with leukemia infiltration assessed by magnetic resonance imaging. The mean maximal standard uptake value was significantly higher in visually CXCR4 positive patients compared to CXCR4 negative patients. In summary, in vivo molecular CXCR4 imaging by means of positron emission tomography is feasible in acute myeloid leukemia. These data provide a framework for future diagnostic and theranostic approaches targeting the CXCR4/CXCL12-defined leukemia-initiating cell niche.
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http://dx.doi.org/10.3324/haematol.2016.142976DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4967572PMC
August 2016