Publications by authors named "Michael Bachmann"

241 Publications

Coexistence of fluorescent strains in millifluidic droplet reactors.

Lab Chip 2021 04;21(8):1492-1502

Institute for Materials Science, Max Bergmann Center of Biomaterials, Technische Universität Dresden, 01062 Dresden, Germany. and Helmholtz-Zentrum Dresden Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328 Dresden, Germany.

Understanding competition and cooperation within microbiota is of high fundamental and clinical importance, helping to comprehend species' evolution and biodiversity. We co-encapsulated and cultured two isogenic Escherichia coli strains expressing blue (BFP) and yellow (YFP) fluorescent proteins into numerous emulsion droplets and quantified their growth by employing fluorescence measurements. To characterize and compare the bacterial growth kinetics and behavior in mono and co-culture, we compared the experimental observations with predictions from a simple growth model. Varying the initial ratio (R0) of both cell types injected, we observed a broad landscape from competition to cooperation between both strains in their confined microenvironments depending on start frequency: from a nearly symmetric situation at R0 = 1, up to the domination of one subpopulation when R0 ≫ 1 (or R0 ≪ 1). Due to competition between the strains, their doubling times and final biomass ratios (R1) continuously deviate from the monoculture behavior. The correlation map of the two strains' doubling times reveals that the R0 is one of the critical parameters affecting the competitive interaction between isogenic bacterial strains. Thanks to this strategy, different species of bacteria can be monitored simultaneously in real-time. Further advantages include high statistical output, unaffected bacteria growth, and long-time measurements in a well-mixed environment. We expect that the millifluidic droplet-based reactor can be utilized for practical clinical applications, such as bacterial antibiotic resistance and enzyme reaction kinetics studies.
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http://dx.doi.org/10.1039/d0lc01204aDOI Listing
April 2021

Two Be or Not Two Be: The Nuclear Autoantigen La/SS-B Is Able to Form Dimers and Oligomers in a Redox Dependent Manner.

Int J Mol Sci 2021 Mar 25;22(7). Epub 2021 Mar 25.

Department of Radioimmunology, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), 01328 Dresden, Germany.

According to the literature, the autoantigen La is involved in Cap-independent translation. It was proposed that one prerequisite for this function is the formation of a protein dimer. However, structural analyses argue against La protein dimers. Noteworthy to mention, these structural analyses were performed under reducing conditions. Here we describe that La protein can undergo redox-dependent structural changes. The oxidized form of La protein can form dimers, oligomers and even polymers stabilized by disulfide bridges. The primary sequence of La protein contains three cysteine residues. Only after mutation of all three cysteine residues to alanine La protein becomes insensitive to oxidation, indicating that all three cysteines are involved in redox-dependent structural changes. Biophysical analyses of the secondary structure of La protein support the redox-dependent conformational changes. Moreover, we identified monoclonal anti-La antibodies (anti-La mAbs) that react with either the reduced or oxidized form of La protein. Differential reactivities to the reduced and oxidized form of La protein were also found in anti-La sera of autoimmune patients.
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http://dx.doi.org/10.3390/ijms22073377DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8036718PMC
March 2021

Expression of Potential Targets for Cell-Based Therapies on Melanoma Cells.

Life (Basel) 2021 Mar 24;11(4). Epub 2021 Mar 24.

Department of Dermatology and National Center for Tumor Diseases, University Hospital Heidelberg, 69120 Heidelberg, Germany.

Tumor antigen-specific redirection of cytotoxic T cells (CTLs) or natural killer (NK) cells including chimeric antigen receptor (CAR-) and T cell receptor (TCR-) cell therapy is currently being evaluated in different tumor entities including melanoma. Expression of melanoma-specific antigen recognized by the respective CAR or TCR directly or presented by HLA molecules is an indispensable prerequisite for this innovative therapy. In this study, we investigated in 168 FFPE tumor specimens of patients with stage I-IV melanoma the protein expression of HER2, TRP2, ABCB5, gp100, p53, and GD2 by immunohistochemistry (IHC). These results were correlated with clinical parameters. Membrane expression of HER2 and GD2 was also investigated in ten melanoma cell lines by flow cytometry for which corresponding tumors were analyzed by IHC. Our results demonstrated that gp100 was the most frequently overexpressed protein (61%), followed by TRP2 (50%), GD2 (38%), p53 (37%), ABCB5 (17%), and HER2 (3%). TRP2 expression was higher in primary tumors compared to metastases ( = 0.005). Accordingly, TRP2 and ABCB5 expression was significantly associated with lower tumor thickness of the primary ( = 0.013 and = 0.025). There was no association between protein expression levels and survival in advanced melanoma patients. Flow cytometric analysis revealed abundant surface expression of GD2 and HER2 in all melanoma cell lines. The discordant HER2 expression in situ and in vitro suggests a tissue culture associated induction. In summary, our data support the use of gp100 and GD2 as a potential target for developing engineered TCR- or CAR-cell therapies, respectively, against melanoma.
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http://dx.doi.org/10.3390/life11040269DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8064084PMC
March 2021

Immune Interaction Map of Human SARS-CoV-2 Target Genes: Implications for Therapeutic Avenues.

Front Immunol 2021 16;12:597399. Epub 2021 Mar 16.

Institute of Medical Immunology, Martin Luther University Halle-Wittenberg, Halle, Germany.

There exists increasing evidence that people with preceding medical conditions, such as diabetes and cancer, have a higher risk of infection with SARS-CoV-2 and are more vulnerable to severe disease. To get insights into the possible role of the immune system upon COVID-19 infection, 2811 genes of the gene ontology term "immune system process GO: 0002376" were selected for coexpression analysis of the human targets of SARS-CoV-2 (HT-SARS-CoV-2) ACE2, TMPRSS2, and FURIN in tissue samples from patients with cancer and diabetes mellitus. The network between HT-SARS-CoV-2 and immune system process genes was analyzed based on functional protein associations using STRING. In addition, STITCH was employed to determine druggable targets. DPP4 was the only immune system process gene, which was coexpressed with the three HT-SARS-CoV-2 genes, while eight other immune genes were at least coexpressed with two HT-SARS-CoV-2 genes. STRING analysis between immune and HT-SARS-CoV-2 genes plotted 19 associations of which there were eight common networking genes in mixed healthy (323) and pan-cancer (11003) tissues in addition to normal (87), cancer (90), and diabetic (128) pancreatic tissues. Using this approach, three commonly applicable druggable connections between HT-SARS-CoV-2 and immune system process genes were identified. These include positive associations of ACE2-DPP4 and TMPRSS2-SRC as well as a negative association of FURIN with ADAM17. Furthermore, 16 drugs were extracted from STITCH (score <0.8) with 32 target genes. Thus, an immunological network associated with HT-SARS-CoV-2 using bioinformatics tools was identified leading to novel therapeutic opportunities for COVID-19.
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http://dx.doi.org/10.3389/fimmu.2021.597399DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8007772PMC
April 2021

Tumor-infiltrating plasmacytoid dendritic cells are associated with survival in human colon cancer.

J Immunother Cancer 2021 Mar;9(3)

Institute of Immunology, Faculty of Medicine Carl Gustav Carus, TU Dresden, Dresden, Germany

Background: Plasmacytoid dendritic cells (pDCs) play a key role in the induction and maintenance of antitumor immunity. Conversely, they can act as tolerogenic DCs by inhibiting tumor-directed immune responses. Therefore, pDCs may profoundly influence tumor progression. To gain novel insights into the role of pDCs in colon cancer, we investigated the frequency and clinical relevance of pDCs in primary tumor tissues from patients with colon cancer with different clinicopathological characteristics.

Methods: Immunohistochemical stainings were performed to explore the frequency of tumor-infiltrating BDCA-2 pDCs in patients with colon cancer. Statistical analyses were conducted to determine an association between the pDC density and clinicopathological characteristics of the patients. Furthermore, we used multiplex immunofluorescence stainings to evaluate the localization and phenotype of pDCs in stroma and tertiary lymphoid structures (TLS) of colon cancer tissues.

Results: An increased density of infiltrating pDCs was associated with lower Union for International Cancer Control (UICC) stages. Furthermore, a higher pDC frequency was significantly correlated with increased progression-free and overall survival of patients with colon cancer. Moreover, a lower number of coloncancer-infiltrating pDCs was significantly and independently linked to worse prognosis. In addition, we found that a proportion of pDCs shows a nuclear expression of the transcription factor interferon regulatory factor 7 (IRF7), which is characteristic for an activated phenotype. In various tumor stroma regions, IRF7 pDCs were located in the neighborhood of granzyme B-expressing CD8 T cells. Moreover, pDCs were identified as a novel component of the T cell zone of colon cancer-associated TLS, which are major regulators of adaptive antitumor immunity. A proportion of TLS-associated pDCs displayed a nuclear IRF7 expression and was preferentially located close to CD4 T cells.

Conclusions: These results indicate that higher densities of tumor-infiltrating pDCs are associated with prolonged survival of patients with colon cancer. Moreover, colon cancer-infiltrating pDCs may represent a novel prognostic factor. The colocalization of activated pDCs and T cells in tumor stroma and within TLS may contribute to the correlation between higher pDC densities and better prognosis. In addition, our findings may have implications for the design of novel immunotherapeutic strategies that are based on targeting colon cancer-infiltrating pDCs.
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http://dx.doi.org/10.1136/jitc-2020-001813DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7993360PMC
March 2021

Development of a ghrelin receptor inverse agonist for positron emission tomography.

Oncotarget 2021 Mar 2;12(5):450-474. Epub 2021 Mar 2.

Institute of Biochemistry, Faculty of Life Sciences, Universität Leipzig, Leipzig, Germany.

Imaging of Ghrelin receptors provides unique potential to gain deeper understanding on Ghrelin and its receptors in health and disease, in particular, in cancer. Ghrelin, an octanoylated 28-mer peptide hormone activates the constitutively active growth hormone secretagogue receptor type 1a (GHS-R1a) with nanomolar activity. We developed novel compounds, derived from the potent inverse agonist K-(D-1-Nal)-FwLL-NH but structurally varied by lysine conjugation with 1,4,7-triazacyclononane,1-glutaric acid-4,7-acetic acid (NODAGA), palmitic acid and/or diethylene glycol (PEG2) to allow radiolabeling and improve pharmacokinetics, respectively. All compounds were tested for receptor binding, potency and efficacy , for biodistribution and -kinetics in rats and in preclinical prostate cancer models on mice. Radiolabeling with Cu-64 and Ga-68 was successfully achieved. The Cu-64- or Ga-68-NODAGA-NH-K-K-(D-1-NaI)-F-w-L-L-NH radiotracer were specifically accumulated by the GHS-R1a in xenotransplanted human prostate tumor models (PC-3, DU-145) in mice. The tumors were clearly delineated by PET. The radiotracer uptake was also partially blocked by K-(D-1-Nal)-FwLL-NH in stomach and thyroid. The presence of the GHS-R1a was also confirmed by immunohistology. In the arterial rat blood plasma, only the original compounds were found. The Cu-64 or Ga-68-NODAGA-NH-K-K-(D-1-NaI)-F-w-L-L-NH radiolabeled inverse agonists turned out to be potent and safe. Due to their easy synthesis, high affinity, medium potency, metabolic stability, and the suitable pharmacokinetic profiles, they are excellent tools for imaging and quantitation of GHS-R1a expression in normal and cancer tissues by PET. These compounds can be used as novel biomarkers of the Ghrelin system in precision medicine.
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http://dx.doi.org/10.18632/oncotarget.27895DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7939532PMC
March 2021

von Willebrand Factor Multimer Formation Contributes to Immunothrombosis in Coronavirus Disease 2019.

Crit Care Med 2021 05;49(5):e512-e520

Medical Department I, University Hospital Marien Hospital Herne, Ruhr-University Bochum, Herne, Germany.

Objectives: Prevention and therapy of immunothrombosis remain crucial challenges in the management of coronavirus disease 2019, since the underlying mechanisms are incompletely understood. We hypothesized that endothelial damage may lead to substantially increased concentrations of von Willebrand factor with subsequent relative deficiency of a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS13).

Design: Prospective controlled cross-over trial.

Setting: Blood samples of patients with confirmed coronavirus disease 2019 and healthy controls were obtained in three German hospitals and analyzed in a German hemostaseologic laboratory.

Patients: Seventy-five patients with confirmed coronavirus disease 2019 of mild to critical severity and 30 healthy controls.

Measurements And Main Results: von Willebrand factor antigen, ADAMTS13, and von Willebrand factor multimer formation were analyzed. von Willebrand factor antigen was 4.1 times higher in COVID-19 patients compared with healthy controls (p < 0.0001), whereas ADAMTS13 activities were not significantly different (p = 0.18). The ADAMTS13/von Willebrand factor antigen ratio was significantly lower in COVID-19 than in the control group (24.4 ± 20.5 vs 82.0 ± 30.7; p < 0.0001). Fourteen patients (18.7%) undercut a critical ratio of 10 as described in thrombotic thrombocytopenic purpura. Gel analysis of multimers resembled a thrombotic thrombocytopenic purpura pattern with loss of the largest multimers in 75% and a smeary triplet pattern in 39% of the patients. The ADAMTS13/von Willebrand factor antigen ratio decreased continuously from mild to critical disease (analysis of variance p = 0.026). Furthermore, it differed significantly between surviving patients and those who died from COVID-19 (p = 0.001) yielding an area under the curve of 0.232 in receiver operating characteristic curve curve analysis.

Conclusion: COVID-19 is associated with a substantial increase in von Willebrand factor levels, which can exceed the ADAMTS13 processing capacity resulting in the formation of large von Willebrand factor multimers indistinguishable from thrombotic thrombocytopenic purpura. The ADAMTS13/von Willebrand factor antigen ratio is an independent predictor of severity of disease and mortality. These findings provide a rationale to consider plasma exchange as a therapeutic option in COVID-19 and to include von Willebrand factor and ADAMTS13 in the diagnostic workup.
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http://dx.doi.org/10.1097/CCM.0000000000004918DOI Listing
May 2021

T Cell Mediated Conversion of a Non-Anti-La Reactive B Cell to an Autoreactive Anti-La B Cell by Somatic Hypermutation.

Int J Mol Sci 2021 Jan 26;22(3). Epub 2021 Jan 26.

Department of Radioimmunology, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), 03128 Dresden, Germany.

Since the first description of nuclear autoantigens in the late 1960s and early 1970s, researchers, including ourselves, have found it difficult to establish monoclonal antibodies (mabs) against nuclear antigens, including the La/SS-B (Sjögrens' syndrome associated antigen B) autoantigen. To date, only a few anti-La mabs have been derived by conventional hybridoma technology; however, those anti-La mabs were not bona fide autoantibodies as they recognize either human La specific, cryptic, or post-translationally modified epitopes which are not accessible on native mouse La protein. Herein, we present a series of novel murine anti-La mabs including truly autoreactive ones. These mabs were elicited from a human La transgenic animal through adoptive transfer of T cells from non-transgenic mice immunized with human La antigen. Detailed epitope and paratope analyses experimentally confirm the hypothesis that somatic hypermutations that occur during T cell dependent maturation can lead to autoreactivity to the nuclear La/SS-B autoantigen.
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http://dx.doi.org/10.3390/ijms22031198DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7865296PMC
January 2021

HIF2alpha-Associated Pseudohypoxia Promotes Radioresistance in Pheochromocytoma: Insights from 3D Models.

Cancers (Basel) 2021 Jan 21;13(3). Epub 2021 Jan 21.

Department of Radiopharmaceutical and Chemical Biology, Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, 01328 Dresden, Germany.

Pheochromocytomas and paragangliomas (PCCs/PGLs) are rare neuroendocrine tumors arising from chromaffin tissue located in the adrenal or ganglia of the sympathetic or parasympathetic nervous system. The treatment of non-resectable or metastatic PCCs/PGLs is still limited to palliative measures, including somatostatin type 2 receptor radionuclide therapy with [Lu]Lu-DOTA-TATE as one of the most effective approaches to date. Nevertheless, the metabolic and molecular determinants of radiation response in PCCs/PGLs have not yet been characterized. This study investigates the effects of hypoxia-inducible factor 2 alpha (HIF2α) on the susceptibility of PCCs/PGLs to radiation treatments using spheroids grown from genetically engineered mouse pheochromocytoma (MPC) cells. The expression of was associated with the significantly increased resistance of MPC spheroids to external X-ray irradiation and exposure to beta particle-emitting [Lu]LuCl compared to -deficient controls. Exposure to [Lu]LuCl provided an increased long-term control of MPC spheroids compared to single-dose external X-ray irradiation. This study provides the first experimental evidence that HIF2α-associated pseudohypoxia contributes to a radioresistant phenotype of PCCs/PGLs. Furthermore, the external irradiation and [Lu]LuCl exposure of MPC spheroids provide surrogate models for radiation treatments to further investigate the metabolic and molecular determinants of radiation responses in PCCs/PGLs and evaluate the effects of neo-adjuvant-in particular, radiosensitizing-treatments in combination with targeted radionuclide therapies.
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http://dx.doi.org/10.3390/cancers13030385DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7865577PMC
January 2021

Comparison of Conformational Phase Behavior for Flexible and Semiflexible Polymers.

Polymers (Basel) 2020 Dec 16;12(12). Epub 2020 Dec 16.

Soft Matter Systems Research Group, Center for Simulational Physics, The University of Georgia, Athens, GA 30602, USA.

We employ the recently introduced generalized microcanonical inflection point method for the statistical analysis of phase transitions in flexible and semiflexible polymers and study the impact of the bending stiffness upon the character and order of transitions between random-coil, globules, and pseudocrystalline conformations. The high-accuracy estimates of the microcanonical entropy and its derivatives required for this study were obtained by extensive replica-exchange Monte Carlo simulations. We observe that the transition behavior into the compact phases changes qualitatively with increasing bending stiffness. Whereas the Θ collapse transition is less affected, the first-order liquid-solid transition characteristic for flexible polymers ceases to exist once bending effects dominate over attractive monomer-monomer interactions.
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http://dx.doi.org/10.3390/polym12123013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7766581PMC
December 2020

Expression, Regulation and Function of microRNA as Important Players in the Transition of MDS to Secondary AML and Their Cross Talk to RNA-Binding Proteins.

Int J Mol Sci 2020 Sep 27;21(19). Epub 2020 Sep 27.

Institute of Medical Immunology, Martin Luther University Halle-Wittenberg, 06112 Halle, Germany.

Myelodysplastic syndromes (MDS), heterogeneous diseases of hematopoietic stem cells, exhibit a significant risk of progression to secondary acute myeloid leukemia (sAML) that are typically accompanied by MDS-related changes and therefore significantly differ to de novo acute myeloid leukemia (AML). Within these disorders, the spectrum of cytogenetic alterations and oncogenic mutations, the extent of a predisposing defective osteohematopoietic niche, and the irregularity of the tumor microenvironment is highly diverse. However, the exact underlying pathophysiological mechanisms resulting in hematopoietic failure in patients with MDS and sAML remain elusive. There is recent evidence that the post-transcriptional control of gene expression mediated by microRNAs (miRNAs), long noncoding RNAs, and/or RNA-binding proteins (RBPs) are key components in the pathogenic events of both diseases. In addition, an interplay between RBPs and miRNAs has been postulated in MDS and sAML. Although a plethora of miRNAs is aberrantly expressed in MDS and sAML, their expression pattern significantly depends on the cell type and on the molecular make-up of the sample, including chromosomal alterations and single nucleotide polymorphisms, which also reflects their role in disease progression and prediction. Decreased expression levels of miRNAs or RBPs preventing the maturation or inhibiting translation of genes involved in pathogenesis of both diseases were found. Therefore, this review will summarize the current knowledge regarding the heterogeneity of expression, function, and clinical relevance of miRNAs, its link to molecular abnormalities in MDS and sAML with specific focus on the interplay with RBPs, and the current treatment options. This information might improve the use of miRNAs and/or RBPs as prognostic markers and therapeutic targets for both malignancies.
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http://dx.doi.org/10.3390/ijms21197140DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7582632PMC
September 2020

Versatile chimeric antigen receptor platform for controllable and combinatorial T cell therapy.

Oncoimmunology 2020 07 3;9(1):1785608. Epub 2020 Jul 3.

Department of Radioimmunology, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, Germany.

Chimeric antigen receptor (CAR) T cells show remarkable therapeutic effects in some hematological malignancies. However, CAR T cells can also cause life-threatening side effects. In order to minimize off-target and on-target/off-tumor reactions, improve safety, enable controllability, provide high flexibility, and increase tumor specificity, we established a novel humanized artificial receptor platform termed RevCARs. RevCAR genes encode for small surface receptors lacking any antigen-binding moiety. Steering of RevCAR T cells occurs via bispecific targeting molecules (TMs). The small size of RevCAR-encoding genes allows the construction of polycistronic vectors. Here, we demonstrate that RevCAR T cells efficiently kill tumor cells, can be steered by TMs, flexibly redirected against multiple targets, and used for combinatorial targeting following the "OR" and "AND" gate logic.
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http://dx.doi.org/10.1080/2162402X.2020.1785608DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7458653PMC
July 2020

Nanocytometer for smart analysis of peripheral blood and acute myeloid leukemia: a pilot study.

Nano Lett 2020 09 27;20(9):6572-6581. Epub 2020 Aug 27.

Max Bergmann Center of Biomaterials and Institute for Materials Science, Dresden University of Technology, Budapesterstrasse 27, 01069 Dresden, Germany.

We realize an ultracompact nanocytometer for real-time impedimetric detection and classification of subpopulations of living cells. Nanoscopic nanowires in a microfluidic channel act as nanocapacitors and measure in real time the change of the amplitude and phase of the output voltage and, thus, the electrical properties of living cells. We perform the cell classification in the human peripheral blood (PBMC) and demonstrate for the first time the possibility to discriminate monocytes and of lymphocytes in a label-free format. Further, we demonstrate that the PBMC of acute myeloid leukemia and healthy samples grant the label free identification of the disease. Using the algorithm based on machine learning, we generated to discriminate healthy donors and leukemia patients. Such a solution has the potential to improve the traditional diagnostics approaches with respect to the overall cost and time effort, in a label-free format, and restrictions of the complex data analysis.
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http://dx.doi.org/10.1021/acs.nanolett.0c02300DOI Listing
September 2020

Highly Efficient Targeting of EGFR-Expressing Tumor Cells with UniCAR T Cells via Target Modules Based on Cetuximab.

Onco Targets Ther 2020 12;13:5515-5527. Epub 2020 Jun 12.

German Cancer Consortium (DKTK), Dresden, Germany.

Introduction: Since epithelial growth factor receptor (EGFR) overexpression is linked to a variety of malignancies, it is an attractive target for immune therapy including chimeric antigen receptor (CAR)-engineered T cells. Unfortunately, CAR T cell therapy harbors the risk of severe, even life-threatening side effects. Adaptor CAR T cell platforms such as the previously described UniCAR system might be able to overcome these problems. In contrast to conventional CARs, UniCAR T cells are per se inert. Their redirection towards target cells occurs only in the presence of a tumor-specific target molecule (TM). TMs are bifunctional molecules being able to recognize a tumor-associated antigen and to cross-link the CAR T cell via a peptide epitope recognized by the UniCAR domain.

Materials And Methods: Here, we compare αEGFR TMs: a nanobody (nb)-based αEGFR TM derived from the camelid αEGFR antibody 7C12 with a murine and humanized single-chain fragment variable (scFv) based on the clinically used antibody Cetuximab.

Results: In principle, both the nb- and scFv-based TM formats are able to redirect UniCAR T cells to eliminate EGFR-expressing tumor cells in an antigen-specific and TM-dependent manner. However, the scFv-based αEGFR TM was significantly superior to the nb-based TM especially with respect to lysis of tumor cells.

Discussion: Improved efficiency of the scFv-based TM allowed the redirection of UniCAR T cells towards tumor cells expressing high as well as low EGFR levels in comparison to nb-based αEGFR TMs.
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http://dx.doi.org/10.2147/OTT.S245169DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7297505PMC
June 2020

Rapidly Switchable Universal CAR-T Cells for Treatment of CD123-Positive Leukemia.

Mol Ther Oncolytics 2020 Jun 29;17:408-420. Epub 2020 Apr 29.

GEMoaB Monoclonals GmbH, 01307 Dresden, Germany.

Chimeric antigen receptor T cells (CAR-T) targeting CD19 or B cell maturation antigen (BCMA) are highly effective against B cell malignancies. However, application of CAR-T to less differentially expressed targets remains a challenge due to lack of tumor-specific antigens and CAR-T controllability. CD123, a highly promising leukemia target, is expressed not only by leukemic and leukemia-initiating cells, but also by myeloid, hematopoietic progenitor, and certain endothelial cells. Thus, CAR-T lacking fine-tuned control mechanisms pose a high toxicity risk. To extend the CAR-T target landscape and widen the therapeutic window, we adapted our rapidly switchable universal CAR-T platform (UniCAR) to target CD123. UniCAR-T efficiently eradicated CD123 leukemia and . Activation, cytolytic response, and cytokine release were strictly dependent on the presence of the CD123-specific targeting module (TM123) with comparable efficacy to CD123-specific CAR-T . We further demonstrated a pre-clinical proof of concept for the safety-switch mechanism using a hematotoxicity mouse model wherein TM123-redirected UniCAR-T showed reversible toxicity toward hematopoietic cells compared to CD123 CAR-T. In conclusion, UniCAR-T maintain full anti-leukemic efficacy, while ensuring rapid controllability to improve safety and versatility of CD123-directed immunotherapy. The safety and efficacy of UniCAR-T in combination with TM123 will now be assessed in a phase I clinical trial (ClinicalTrials.gov: NCT04230265).
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http://dx.doi.org/10.1016/j.omto.2020.04.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7240059PMC
June 2020

Adaptor CAR Platforms-Next Generation of T Cell-Based Cancer Immunotherapy.

Cancers (Basel) 2020 May 21;12(5). Epub 2020 May 21.

Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), 01328 Dresden, Germany.

The success of conventional chimeric antigen receptor (CAR) therapy in the treatment of refractory hematologic malignancies has triggered the development of novel exciting experimental CAR technologies. Among them, adaptor CAR platforms have received much attention. They combine the flexibility and controllability of recombinant antibodies with the power of CARs. Due to their modular design, adaptor CAR systems propose answers to the central problems of conventional CAR therapy, such as safety and antigen escape. This review provides an overview on the different adaptor CAR platforms available, discusses the possibilities and challenges of adaptor CAR therapy, and summarizes the first clinical experiences.
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http://dx.doi.org/10.3390/cancers12051302DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7281723PMC
May 2020

UniCAR T cell immunotherapy enables efficient elimination of radioresistant cancer cells.

Oncoimmunology 2020 5;9(1):1743036. Epub 2020 Apr 5.

Department of Radioimmunology, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiopharmaceutical Cancer Research, Dresden, Germany.

Induction or selection of radioresistant cancer (stem) cells following standard radiotherapy is presumably one of the major causes for recurrence of metastatic disease. One possibility to prevent tumor relapse is the application of targeted immunotherapies including, e.g., chimeric antigen receptor (CAR) T cells. In light of long-term remissions, it is highly relevant to clarify whether radioresistant cancer cells are susceptible to CAR T cell-mediated killing. To answer this question, we evaluated the anti-tumor activity of the switchable universal chimeric antigen receptor (UniCAR) system against highly radioresistant head and neck squamous cell carcinoma cells both and . Following specific UniCAR T cell engagement via EGFR or CD98 target modules, T cell effector mechanisms were induced including secretion of pro-inflammatory cytokines, up-regulation of granzyme B and perforin, as well as T cell proliferation. CD98- or EGFR-redirected UniCAR T cells further possess the capability to efficiently lyse radioresistant tumor cells. Observed anti-tumor effects were comparable to those against the radiosensitive parental cell lines. Finally, redirected UniCAR T cells significantly inhibited the growth of radioresistant cancer cells in immunodeficient mice. Taken together, our obtained data underline that the UniCAR system is able to overcome radioresistance. Thus, it represents an attractive technology for the development of combined radioimmunotherapeutic approaches that might improve the outcome of patients with metastatic radioresistant tumor diseases.
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http://dx.doi.org/10.1080/2162402X.2020.1743036DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7219270PMC
April 2020

Medical Student Ultrasound Education, a WFUMB Position Paper, Part II. A consensus statement of ultrasound societies.

Med Ultrason 2020 May;22(2):220-229

Department Allgemeine Innere Medizin (DAIM), Kliniken Hirslanden Beau Site, Salem und Permanence, Bern, Switzerland Ultrasound Department, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China.

Ultrasound is becoming a fundamental first-line diagnostic tool for most medical specialties and an innovative tool to teach anatomy, physiology and pathophysiology to undergraduate and graduate students. However, availability of structured training programs during medical school is lagging behind and many physicians still acquire all their ultrasound skills during postgraduate training.There is wide variation in medical student ultrasound education worldwide. Sharing successful educational strategies from early adopter medical schools and learning from leading education programs should advance the integration of ultrasound into the university medical school curricula. In this overview, we present current approaches and suggestions by ultrasound societies concerning medical student educa-tion throughout the world. Based on these examples, we formulate a consensus statement with suggestions on how to integrate ultrasound teaching into the preclinical and clinical medical curricula.
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http://dx.doi.org/10.11152/mu-2599DOI Listing
May 2020

Extended half-life target module for sustainable UniCAR T-cell treatment of STn-expressing cancers.

J Exp Clin Cancer Res 2020 May 5;39(1):77. Epub 2020 May 5.

Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiopharmaceutical Cancer Research, Bautzner Landstrasse 400, 01328, Dresden, Germany.

Background: Adapter chimeric antigen receptor (CAR) approaches have emerged has promising strategies to increase clinical safety of CAR T-cell therapy. In the UniCAR system, the safety switch is controlled via a target module (TM) which is characterized by a small-size and short half-life. The rapid clearance of these TMs from the blood allows a quick steering and self-limiting safety switch of UniCAR T-cells by TM dosing. This is mainly important during onset of therapy when tumor burden and the risk for severe side effects are high. For long-term UniCAR therapy, the continuous infusion of TMs may not be an optimal setting for the patients. Thus, in later stages of treatment, single infusions of TMs with an increased half-life might play an important role in long-term surveillance and eradication of residual tumor cells. Given this, we aimed to develop and characterize a novel TM with extended half-life targeting the tumor-associated carbohydrate sialyl-Tn (STn).

Methods: The extended half-life TM is composed of the STn-specific single-chain variable fragment (scFv) and the UniCAR epitope, fused to the hinge region and Fc domain of a human immunoglobulin 4 (IgG4) antibody. Specific binding and functionality of the αSTn-IgG4 TM as well as pharmacokinetic features were assessed using in vitro and in vivo assays and compared to the already established small-sized αSTn TM.

Results: The novel αSTn-IgG4 TM efficiently activates and redirects UniCAR T-cells to STn-expressing tumors in a target-specific and TM-dependent manner, thereby promoting the secretion of proinflammatory cytokines and tumor cell lysis in vitro and in experimental mice. Moreover, PET-imaging results demonstrate the specific enrichment of the αSTn-IgG4 TM at the tumor site, while presenting a prolonged serum half-life compared to the short-lived αSTn TM.

Conclusion: In a clinical setting, the combination of TMs with different formats and pharmacokinetics may represent a promising strategy for retargeting of UniCAR T-cells in a flexible, individualized and safe manner at particular stages of therapy. Furthermore, as these molecules can be used for in vivo imaging, they pose as attractive candidates for theranostic approaches.
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http://dx.doi.org/10.1186/s13046-020-01572-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7201957PMC
May 2020

Characteristics of Tumor-Infiltrating Lymphocytes Prior to and During Immune Checkpoint Inhibitor Therapy.

Front Immunol 2020 4;11:364. Epub 2020 Mar 4.

Faculty of Medicine Carl Gustav Carus, Institute of Immunology, TU Dresden, Dresden, Germany.

The tumor immune contexture plays a major role for the clinical outcome of patients. High densities of CD45RO T helper 1 cells and CD8 T cells are associated with improved survival of patients with various cancer entities. In contrast, a higher frequency of tumor-infiltrating M2 macrophages is correlated with poor prognosis. Recent studies provide evidence that the tumor immune architecture also essentially contributes to the clinical efficacy of immune checkpoint inhibitor (CPI) therapy in patients. Pretreatment melanoma samples from patients who experienced a clinical response to anti-programmed cell death protein 1 (PD-1) treatment show higher densities of infiltrating CD8 T cells compared to samples from patients that progressed during therapy. Anti-PD-1 therapy results in an increased density of tumor-infiltrating T lymphocytes in treatment responders. In addition, elevated frequencies of melanoma-infiltrating TCF7CD8 T cells are correlated with beneficial clinical outcome of anti-PD-1-treated patients. In contrast, a high density of tumor-infiltrating, dysfunctional PD-1CD38 CD8 cells in melanoma patients is associated with anti-PD-1 resistance. Such findings indicate that comprehensive tumor immune contexture profiling prior to and during CPI therapy may lead to the identification of underlying mechanisms for treatment response or resistance, and the design of improved immunotherapeutic strategies. Here, we focus on studies exploring the impact of intratumoral T and B cells at baseline on the clinical outcome of CPI-treated cancer patients. In addition, recent findings demonstrating the influence of CPIs on tumor-infiltrating lymphocytes are summarized.
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http://dx.doi.org/10.3389/fimmu.2020.00364DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7064638PMC
March 2021

Induction of ligand promiscuity of αVβ3 integrin by mechanical force.

J Cell Sci 2020 05 11;133(9). Epub 2020 May 11.

Zoological Institute, Cell and Neurobiology, Karlsruhe Institute of Technology (KIT), Karlsruhe 76131, Germany

αVβ3 integrin can bind to multiple extracellular matrix proteins, including vitronectin (Vn) and fibronectin (Fn), which are often presented to cells in culture as homogenous substrates. However, in tissues, cells experience highly complex and changing environments. To better understand integrin ligand selection in such complex environments, we employed binary-choice substrates of Fn and Vn to dissect αVβ3 integrin-mediated binding to different ligands on the subcellular scale. Super-resolution imaging revealed that αVβ3 integrin preferred binding to Vn under various conditions. In contrast, binding to Fn required higher mechanical load on αVβ3 integrin. Integrin mutations, structural analysis and chemical inhibition experiments indicated that the degree of hybrid domain swing-out is relevant for the selection between Fn and Vn; only a force-mediated, full hybrid domain swing-out facilitated αVβ3-Fn binding. Thus, force-dependent conformational changes in αVβ3 integrin increased the diversity of available ligands for binding and therefore enhanced the ligand promiscuity of this integrin.This article has an associated First Person interview with the first author of the paper.
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http://dx.doi.org/10.1242/jcs.242404DOI Listing
May 2020

Bidirectional Crosstalk Between Cancer Stem Cells and Immune Cell Subsets.

Front Immunol 2020 5;11:140. Epub 2020 Feb 5.

Faculty of Medicine Carl Gustav Carus, Institute of Immunology, TU Dresden, Dresden, Germany.

Cancer stem cells (CSCs), also known as tumor-initiating cells, are characterized by an increased capacity for self-renewal, multipotency, and tumor initiation. While CSCs represent only a small proportion of the tumor mass, they significantly account for metastatic dissemination and tumor recurrence, thus making them attractive targets for therapy. Due to their ability to sustain in dormancy, chemo- and radiotherapy often fail to eliminate cancer cells with stemness properties. Recent advances in the understanding of the tumor microenvironment (TME) illustrated the importance of the immune contexture, determining the response to therapy and clinical outcome of patients. In this context, CSCs exhibit special properties to escape the recognition by innate and adaptive immunity and shape the TME into an immunosuppressive, pro-tumorigenic landscape. As CSCs sculpt the immune contexture, the phenotype and functional properties of the tumor-infiltrating immune cells in turn influence the differentiation and phenotype of tumor cells. In this review, we summarize recent studies investigating main immunomodulatory properties of CSCs and their underlying molecular mechanisms as well as the impact of immune cells on cancer cells with stemness properties. A deeper understanding of this bidirectional crosstalk shaping the immunological landscape and determining therapeutic responses will facilitate the improvement of current treatment modalities and the design of innovative strategies to precisely target CSCs.
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http://dx.doi.org/10.3389/fimmu.2020.00140DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7013084PMC
March 2021

Synthesis, Labeling and Preclinical Evaluation of a Squaric Acid Containing PSMA Inhibitor Labeled with Ga: A Comparison with PSMA-11 and PSMA-617.

ChemMedChem 2020 04 19;15(8):695-704. Epub 2020 Mar 19.

Institute of Nuclear Chemistry, Johannes Gutenberg University, Fritz-Strassmann-Weg 2, 55128, Mainz, Germany.

The L-lysine urea-L-glutamate (KuE) represents a key motif in recent diagnostic and therapeutic radiopharmaceuticals targeting the prostate specific membrane antigen (PSMA). Using a squaric acid moiety for coupling of KuE with a radioactive label, the squaric acid as a linker in the PSMA ligand seems to mimic the aromatic structure of the naphthylalanine unit on PSMA-617. In this work, we investigate the influence of squaric acid moiety on the biological activity of the compound carrying a KuE motif and three typical chelates. The derivatives TRAM.SA.KuE, DOTAGA.SA.KuE and NODAGA.SA.KuE were all synthesized in straightforward organic reactions and purified by HPLC afterward. Different amounts of tracer were labeled at different temperatures with Ga. PET examinations were performed on NMRInu/nu nude mice with an LNCaP tumor on the right hind leg including ex vivo investigations of the organs. For comparison, Ga-derivatives of PSMA-11 and PSMA-617, the derivatives most commonly used in clinics, were investigated in the same animal model.
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http://dx.doi.org/10.1002/cmdc.201900559DOI Listing
April 2020

"UniCAR"-modified off-the-shelf NK-92 cells for targeting of GD2-expressing tumour cells.

Sci Rep 2020 02 7;10(1):2141. Epub 2020 Feb 7.

Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiopharmaceutical Cancer Research, Dresden, Germany.

Antigen-specific redirection of immune effector cells with chimeric antigen receptors (CARs) demonstrated high therapeutic potential for targeting cancers of different origins. Beside CAR-T cells, natural killer (NK) cells represent promising alternative effectors that can be combined with CAR technology. Unlike T cells, primary NK cells and the NK cell line NK-92 can be applied as allogeneic off-the-shelf products with a reduced risk of toxicities. We previously established a modular universal CAR (UniCAR) platform which consists of UniCAR-expressing immune cells that cannot recognize target antigens directly but are redirected by a tumour-specific target module (TM). The TM contains an antigen-binding moiety fused to a peptide epitope which is recognized by the UniCAR molecule, thereby allowing an on/off switch of CAR activity, and facilitating flexible targeting of various tumour antigens depending on the presence and specificity of the TM. Here, we provide proof of concept that it is feasible to generate a universal off-the-shelf cellular therapeutic based on UniCAR NK-92 cells targeted to tumours expressing the disialoganglioside GD2 by GD2-specific TMs that are either based on an antibody-derived single-chain fragment variable (scFv) or an IgG4 backbone. Redirected UniCAR NK-92 cells induced specific killing of GD2-expressing cells in vitro and in vivo, associated with enhanced production of interferon-γ. Analysis of radiolabelled proteins demonstrated that the IgG4-based format increased the in vivo half-life of the TM markedly in comparison to the scFv-based molecule. In summary, UniCAR NK-92 cells represent a universal off-the-shelf platform that is highly effective and flexible, allowing the use of different TM formats for specific tumour targeting.
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http://dx.doi.org/10.1038/s41598-020-59082-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7005792PMC
February 2020

Versatile Bispidine-Based Bifunctional Chelators for Cu -Labelling of Biomolecules.

Chemistry 2020 Feb 9;26(9):1989-2001. Epub 2020 Jan 9.

Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstrasse 400, 01328, Dresden, Germany.

Bifunctional chelators as parts of modular metal-based radiopharmaceuticals are responsible for stable complexation of the radiometal ion and for covalent linkage between the complex and the targeting vector. To avoid loss of complex stability, the bioconjugation strategy should not interfere with the radiometal chelation by occupying coordinating groups. The C9 position of the very stable Cu chelator 3,7-diazabicyclo[3.3.1]nonane (bispidine) is virtually predestined to introduce functional groups for facile bioconjugation as this functionalisation does not disturb the metal binding centre. We describe the preparation and characterisation of a set of novel bispidine derivatives equipped with suitable functional groups for diverse bioconjugation reactions, including common amine coupling strategies (bispidine-isothiocyanate) and the Cu-free strain-promoted alkyne-azide cycloaddition. We demonstrate their functionality and versatility in an exemplary way by conjugation to an antibody-based biomolecule and validate the obtained conjugate in vitro and in vivo.
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http://dx.doi.org/10.1002/chem.201904654DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7028042PMC
February 2020

Radioimmunotherapy in Combination with Reduced-Intensity Conditioning for Allogeneic Hematopoietic Cell Transplantation in Patients with Advanced Multiple Myeloma.

Biol Blood Marrow Transplant 2020 04 12;26(4):691-697. Epub 2019 Nov 12.

Medical Clinic and Polyclinic I, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany; German Cancer Consortium, partner site Dresden, Germany, and German Cancer Research Center, Heidelberg, Germany; National Center for Tumor Diseases, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany.

Radioimmunotherapy (RIT) has the potential to reduce the incidence of relapse after allogeneic hematopoietic cell transplantation (allo-HCT) in patients with advanced-stage multiple myeloma (MM). In this study, we evaluated the efficacy of RIT in combination with chemotherapy-based reduced-intensity conditioning (RIC). RIT was based on the coupling of an anti-CD66 antibody to the beta emitter 188-rhenium (188-re) for targeted bone marrow irradiation. Between 2012 and 2018, 30 patients with MM, most of them heavily pretreated with various therapies including proteasome inhibitors, immunomodulatory drugs, anti-CD38 antibodies, and autologous hematopoietic cell transplantation (auto-HCT), were treated with a RIT-RIC combination before allo-HCT. In addition to a fludarabine plus melphalan- or treosulfan-based RIC, a median dose of 18.1 Gy (interquartile range [IQR], 14.6 to 24.1 Gy) was applied to the bone marrow. After a median duration of follow-up for surviving patients of 2.1 years (IQR, 1.3 to 3.0 years), the 2-year progression-free survival and overall survival rates were 43% (95% confidence interval [CI], 26% to 73%) and 55% (95% CI, 38% to 79%), respectively. The 2-year nonrelapse mortality and cumulative incidence of progression were 17% (95% CI, 3% to 30%) and 46% (95% CI, 25% to 67%), respectively. Renal toxicity and mucositis were the most frequent extramedullary side effects. In conclusion, the addition of RIT to RIC was safe and feasible and resulted in promising outcomes compared with those previously reported for RIC-based allo-HCT without the addition of RIT in patients with relapsed/refractory MM. Nevertheless, despite the addition of RIT, relapse after allo-HCT remained a major determinant of therapeutic failure. Therefore, the development of novel RIT strategies (eg, dual targeting strategies or combinations with adapter chimeric antigen receptor T cell-based therapies) is needed.
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http://dx.doi.org/10.1016/j.bbmt.2019.11.007DOI Listing
April 2020

A theranostic PSMA ligand for PET imaging and retargeting of T cells expressing the universal chimeric antigen receptor UniCAR.

Oncoimmunology 2019;8(11):1659095. Epub 2019 Sep 7.

Department of Radioimmunology, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, Germany.

Chimeric antigen receptor (CAR) T cells have shown impressive therapeutic potential. Due to the lack of direct control mechanisms, therapy-related adverse reactions including cytokine release- and tumor lysis syndrome can even become life-threatening. In case of target antigen expression on non-malignant cells, CAR T cells can also attack healthy tissues. To overcome such side effects, we have established a modular CAR platform termed UniCAR: UniCAR T cells per se are inert as they recognize a peptide epitope (UniCAR epitope) that is not accessible on the surface of living cells. Bifunctional adapter molecules termed target modules (TM) can cross-link UniCAR T cells with target cells. In the absence of TMs, UniCAR T cells automatically turn off. Until now, all UniCAR TMs were constructed by fusion of the UniCAR epitope to an antibody domain. To open up the wide field of low-molecular-weight compounds for retargeting of UniCAR T cells to tumor cells, and to follow in parallel the progress of UniCAR T cell therapy by PET imaging we challenged the idea to convert a PET tracer into a UniCAR-TM. For proof of concept, we selected the clinically used PET tracer PSMA-11, which binds to the prostate-specific membrane antigen overexpressed in prostate carcinoma. Here we show that fusion of the UniCAR epitope to PSMA-11 results in a low-molecular-weight theranostic compound that can be used for both retargeting of UniCAR T cells to tumor cells, and for non-invasive PET imaging and thus represents a member of a novel class of theranostics.
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http://dx.doi.org/10.1080/2162402X.2019.1659095DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6791425PMC
September 2019

The Evolving Landscape of Biomarkers for Anti-PD-1 or Anti-PD-L1 Therapy.

J Clin Med 2019 Sep 25;8(10). Epub 2019 Sep 25.

National Center for Tumor Diseases (NCT), University Hospital Carl Gustav Carus, TU Dresden, Fetscherstraße 74, 01307 Dresden, Germany.

The administration of antibodies blocking the immune checkpoint molecules programmed cell death protein 1 (PD-1) or programmed cell death 1 ligand 1 (PD-L1) has evolved as a very promising treatment option for cancer patients. PD-1/PD-L1 inhibition has significantly enhanced expansion, cytokine secretion, and cytotoxic activity of CD4 and CD8 T lymphocytes, resulting in enhanced antitumor responses. Anti-PD-1 or anti-PD-L1 therapy has induced tumor regression and improved clinical outcome in patients with different tumor entities, including melanoma, non-small-cell lung cancer, and renal cell carcinoma. These findings led to the approval of various anti-PD-1 or anti-PD-L1 antibodies for the treatment of tumor patients. However, the majority of patients have failed to respond to this treatment modality. Comprehensive immune monitoring of clinical trials led to the identification of potential biomarkers distinguishing between responders and non-responders, the discovery of modes of treatment resistance, and the design of improved immunotherapeutic strategies. In this review article, we summarize the evolving landscape of biomarkers for anti-PD-1 or anti-PD-L1 therapy.
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http://dx.doi.org/10.3390/jcm8101534DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6832659PMC
September 2019

Conventional CARs versus modular CARs.

Cancer Immunol Immunother 2019 Oct 21;68(10):1713-1719. Epub 2019 Sep 21.

Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328, Dresden, Germany.

The clinical application of immune effector cells genetically modified to express chimeric antigen receptors (CARs) has shown impressive results including complete remissions of certain malignant hematological diseases. However, their application can also cause severe side effects such as cytokine release syndrome (CRS) or tumor lysis syndrome (TLS). One limitation of currently applied CAR T cells is their lack of regulation. Especially, an emergency shutdown of CAR T cells in case of life-threatening side effects is missing. Moreover, targeting of tumor-associated antigens (TAAs) that are not only expressed on tumor cells but also on vital tissues requires the possibility of a switch allowing to repeatedly turn the activity of CAR T cells on and off. Here we summarize the development of a modular CAR variant termed universal CAR (UniCAR) system that promises to overcome these limitations of conventional CARs.
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http://dx.doi.org/10.1007/s00262-019-02399-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6805801PMC
October 2019

Microvesicle-Mediated Delivery of Minicircle DNA Results in Effective Gene-Directed Enzyme Prodrug Cancer Therapy.

Mol Cancer Ther 2019 12 26;18(12):2331-2342. Epub 2019 Aug 26.

Department of Pediatrics, Stanford University, Stanford, California.

An emerging approach for cancer treatment employs the use of extracellular vesicles, specifically exosomes and microvesicles, as delivery vehicles. We previously demonstrated that microvesicles can functionally deliver plasmid DNA to cells and showed that plasmid size and sequence, in part, determine the delivery efficiency. In this study, delivery vehicles comprised of microvesicles loaded with engineered minicircle (MC) DNA that encodes prodrug converting enzymes developed as a cancer therapy in mammary carcinoma models. We demonstrated that MCs can be loaded into shed microvesicles with greater efficiency than their parental plasmid counterparts and that microvesicle-mediated MC delivery led to significantly higher and more prolonged transgene expression in recipient cells than microvesicles loaded with the parental plasmid. Microvesicles loaded with MCs encoding a thymidine kinase (TK)/nitroreductase (NTR) fusion protein produced prolonged TK-NTR expression in mammary carcinoma cells. delivery of TK-NTR and administration of prodrugs led to the effective killing of both targeted cells and surrounding tumor cells via TK-NTR-mediated conversion of codelivered prodrugs into active cytotoxic agents. evaluation of the bystander effect in mouse models demonstrated that for effective therapy, at least 1% of tumor cells need to be delivered with TK-NTR-encoding MCs. These results suggest that MC delivery via microvesicles can mediate gene transfer to an extent that enables effective prodrug conversion and tumor cell death such that it comprises a promising approach to cancer therapy.
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http://dx.doi.org/10.1158/1535-7163.MCT-19-0299DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6891168PMC
December 2019