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Background: Chimeric antigen receptor (CAR)-T cells represent a potentially curative strategy for patients with relapsed or refractory (R/R) B-cell malignancies. To elucidate a possible host immune activation following CAR-T-cell infusion, we investigated the effects of tisagenlecleucel administration on the patients’ immune populations in 25 patients with R/R diffuse large B-cell lymphoma (DLBCL) and B-lineage acute lymphoblastic leukemia (B-ALL). Methods: The modulation of CAR-T cells over time, the numeric changes, as well as the cytokine production capability of different lymphocyte populations and circulating cytokine levels, were analyzed. Results: Our results confirmed the ability of tisagenlecleucel to control the disease, with an overall response observed in 84.6% of DLBCL and in 91.7% of B-ALL patients at 1-month post-infusion, and showed that most patients who subsequently relapsed could undergo further treatment. Interestingly, we could document a significant increase in CD3+, CD4+, CD8+, and NK cells over time, as well as a decrease in Treg cells, and an increased IFNγ and TNFα production by T lymphocytes. Conclusions: Taken together, our results indicate that in patients with DLBCL and B-ALL, the administration of tisagenlecleucel is capable of inducing a marked and prolonged in vivo modulation/reshaping of the host immune system, both in children and adults.

Objective interpretation of FC results may still be hampered by limited technical standardization. The EuroFlow consortium conducted a series of experiments to determine the impact of different variables on the relative distribution and the median fluorescence intensity (MFI) of markers stained on different cell populations, from both healthy donors and patients’ samples with distinct hematological malignancies. The use of different anticoagulants; the time interval between sample collection, preparation, and acquisition; pH of washing buffers; and the use of cell surface membrane-only (SM) vs. cell surface plus intracytoplasmic (SM+CY) staining protocols, were evaluated. Our results showed that only monocytes were represented at higher percentages in EDTA- vs. heparin-anticoagulated samples. Application of SM or SM+CY protocols resulted in slight differences in the percentage of neutrophils and debris determined only with particular antibody combinations. In turn, storage of samples for 24 h at RT was associated with greater percentage of debris and cell doublets when the plasma cell disorder panel was used. Furthermore, 24 h storage of stained cells at RT was selectively detrimental for MFI levels of CD19 and CD45 on mature B- and T-cells (but not on leukemic blasts, clonal B- and plasma cells, neutrophils, and NK cells). The obtained results showed that the variables evaluated might need to be tailored for sample and cell type(s) as well as to the specific markers compared; however, defining of well-balanced boundaries for storage time, staining-to-acquisition delay, and pH of washing buffer would be a valid recommendation for most applications and circumstances described herein., This research was funded by the EuroFlow Consortium which received support from the FP6-2004-LIFESCIHEALTH-5 program of the European Commission (grant LSHB-CT-2006-018708) as Specific Targeted Research Project (STREP). The EuroFlow Consortium is part of the European Scientific Foundation for Hemato-Oncology (ESLHO), a Scientific Working Group (SWG) of the European Hematology Association (EHA); the grant of the Polish National Center for Research and Development (no. STRATEGMED3/304586/5/NCBR/2017 Person ALL); and internal grant of the Medical University of Silesia (no. PCN-1-050/K/0/K); the grant of CIBER-ONC, Instituto de Salud Carlos III, Ministerio de Economía y Competitividad, Madrid, Spain and FONDOS FEDER (no. CB16/12/00400).

The standardized EuroFlow protocol, including CD19 as primary B-cell marker, enables highly sensitive and reliable minimal residual disease (MRD) assessment in B-cell precursor acute lymphoblastic leukaemia (BCP-ALL) patients treated with chemotherapy. We developed and validated an alternative gating strategy allowing reliable MRD analysis in BCP-ALL patients treated with CD19-targeting therapies. Concordant data were obtained in 92% of targeted therapy patients who remained CD19-positive, whereas this was 81% in patients that became (partially) CD19-negative. Nevertheless, in both groups median MRD values showed excellent correlation with the original MRD data, indicating that, despite higher interlaboratory variation, the overall MRD analysis was correct., The EuroFlow Consortium received support from the FP6-2004-LIFESCIHEALTH-5 programme of the European Commission (grant LSHB-CT-2006-018708) as Specific Targeted Research Project (STREP). The EuroFlow Consortium is part of the European Scientific Foundation for Hemato-Oncology (ESLHO), a Scientific Working Group (SWG) of the European Hematology Association (EHA). TS and LS were supported by a Scientific Grant from the Medical University of Silesia Nr. PCN-1-050/K/0/K.

BackgroundT-cell acute lymphoblastic leukemia (T-ALL) is an aggressive disease with a poor cure rate for relapsed/resistant patients. Due to the lack of T-cell restricted targetable antigens, effective immune-therapeutics are not presently available and the treatment of chemo-refractory T-ALL is still an unmet clinical need. To develop novel immune-therapy for T-ALL, we generated an afucosylated monoclonal antibody (mAb) (ahuUMG1) and two different bispecific T-cell engagers (BTCEs) against UMG1, a unique CD43-epitope highly and selectively expressed by T-ALL cells from pediatric and adult patients.MethodsUMG1 expression was assessed by immunohistochemistry (IHC) on a wide panel of normal tissue microarrays (TMAs), and by flow cytometry on healthy peripheral blood/bone marrow-derived cells, on 10 different T-ALL cell lines, and on 110 T-ALL primary patient-derived cells. CD43-UMG1 binding site was defined through a peptide microarray scanning. ahuUMG1 was generated by Genetic Glyco-Engineering technology from a novel humanized mAb directed against UMG1 (huUMG1). BTCEs were generated as IgG1-(scFv)2 constructs with bivalent (2+2) or monovalent (2+1) CD3ε arms. Antibody dependent cellular cytotoxicity (ADCC), antibody dependent cellular phagocytosis (ADCP) and redirected T-cell cytotoxicity assays were analysed by flow cytometry. In vivo antitumor activity of ahUMG1 and UMG1-BTCEs was investigated in NSG mice against subcutaneous and orthotopic xenografts of human T-ALL.ResultsAmong 110 T-ALL patient-derived samples, 53 (48.1%) stained positive (24% of TI/TII, 82% of TIII and 42.8% of TIV). Importantly, no expression of UMG1-epitope was found in normal tissues/cells, excluding cortical thymocytes and a minority (2 log lower as compared with ahuUMG1, with significant mice survival advantage in different T-ALL models in vivo.ConclusionAltogether our findings, including the safe UMG1-epitope expression profile, provide a framework for the clinical development of these innovative immune-therapeutics for this still orphan disease.

© The Author(s) 2020., Precise classification of acute leukemia (AL) is crucial for adequate treatment. EuroFlow has previously designed an AL orientation tube (ALOT) to guide toward the relevant classification panel and final diagnosis. In this study, we designed and validated an algorithm for automated (database-supported) gating and identification (AGI tool) of cell subsets within samples stained with ALOT. A reference database of normal peripheral blood (PB, n = 41) and bone marrow (BM; n = 45) samples analyzed with the ALOT was constructed, and served as a reference for the AGI tool to automatically identify normal cells. Populations not unequivocally identified as normal cells were labeled as checks and were classified by an expert. Additional normal BM (n = 25) and PB (n = 43) and leukemic samples (n = 109), analyzed in parallel by experts and the AGI tool, were used to evaluate the AGI tool. Analysis of normal PB and BM samples showed low percentages of checks ( 0.95 for all cell types in PB and r2 > 0.75 in BM) and resulted in highly concordant classification of leukemic cells by our previously published automated database-guided expert-supervised orientation tool for immunophenotypic diagnosis and classification of acute leukemia (Compass tool). Similar data were obtained using alternative, commercially available tubes, confirming the robustness of the developed tools. The AGI tool represents an innovative step in minimizing human intervention and requirements in expertise, toward a “sample-in and result-out” approach which may result in more objective and reproducible data analysis and diagnostics. The AGI tool may improve quality of immunophenotyping in individual laboratories, since high percentages of checks in normal samples are an alert on the quality of the internal procedures., The EuroFlow Consortium received support from the FP6- 2004-LIFESCIHEALTH-5 program of the European Commission (grant LSHB-CT-2006-018708) as Specific Targeted Research Project (STREP). The Prague team received support from the grant number NV18-03-00343. The Salamanca team received support from the Instituto de Salud Carlos III (ISCIII) (PI16/00787-FEDER) and from Agencia Estatal de Investigación (RTC-2016-4865-1-FEDER), Ministerio de Economía y Competitividad, Madrid, Spain. AHD is supported from the program DI-17-09591 from Agencia Estatal de Investigación, Ministerio de Ciencia, Innovación y Universidades, Madrid, Spain. SB is supported from the program PTQ16-08364 from Agencia Estatal de Investigación, Ministerio de Ciencia, Innovación y Universidades, Madrid, Spain. Medical University of Silesia in Katowice team was supported by the Strategmed III PersonALL grant [No. 304586/5/NCBR/2017] from the Polish National Center of Research and Development. The EuroFlow Consortium is part of the European Scientific Foundation for Hemato-Oncology (ESLHO), a Scientific Working Group (SWG) of the European Hematology Association (EHA).

The successful implementation of chimeric antigen receptor (CAR)-T cell therapy in the clinical context of B cell malignancies has paved the way for further development in the more critical setting of acute myeloid leukemia (AML). Among the potentially targetable AML antigens, CD33 is insofar one of the main validated molecules. Here, we describe the feasibility of engineering cytokine-induced killer (CIK) cells with a CD33.CAR by using the latest optimized version of the non-viral Sleeping Beauty (SB) transposon system "SB100X-pT4." This offers the advantage of improving CAR expression on CIK cells, while reducing the amount of DNA transposase as compared to the previously employed "SB11-pT" version. SB-modified CD33.CAR-CIK cells exhibited significant antileukemic activity invitro and invivo in patient-derived AML xenograft models, reducing AML development when administered as an "early treatment" and delaying AML progression in mice with established disease. Notably, by exploiting an already optimized xenograft chemotherapy model that mimics human induction therapy in mice, we demonstrated for the first time that CD33.CAR-CIK cells are also effective toward chemotherapy resistant/residual AML cells, further supporting its future clinical development and implementation within the current standard regimens.

On behalf of the EuroFlow Consortium., [Background]: Optimal discrimination between leukemic blasts and normal B-cell precursors (BCP) is critical for treatment monitoring in BCP acute lymphoblastic leukemia (ALL); thus identification of markers differentially expressed on normal BCP and leukemic blasts is required., [Methods]: Multicenter analysis of CD73, CD86 and CD304 expression levels was performed in 282 pediatric BCP-ALL patients vs. normal bone marrow BCP, using normalized median fluorescence intensity (nMFI) values., [Results]: CD73 was expressed at abnormally higher levels (vs. pooled normal BCP) at diagnosis in 71/108 BCP-ALL patients (66%), whereas CD304 and CD86 in 119/202 (59%) and 58/100 (58%) patients, respectively. Expression of CD304 was detected at similar percentages in common-ALL and pre-B-ALL, while found at significantly lower frequencies in pro-B-ALL. A significant association (p = 0.009) was found between CD304 expression and the presence of the ETV6-RUNX1 fusion gene. In contrast, CD304 showed an inverse association with MLL gene rearrangements (p = 0.01). The expression levels of CD73, CD86 and CD304 at day 15 after starting therapy (MRD15) were stable or higher than at diagnosis in 35/37 (95%), 40/56 (71%) and 19/41 (46%) cases investigated, respectively. This was also associated with an increased mean nMFI at MRD15 vs. diagnosis of +24 and +3 nMFI units for CD73 and CD86, respectively. In addition, gain of expression of CD73 and CD86 at MRD15 for cases that were originally negative for these markers at diagnosis was observed in 16% and 18% of cases, respectively. Of note, CD304 remained aberrantly positive in 63% of patients, despite its levels of expression decreased at follow-up in 54% of cases., [Conclusions]: Here we show that CD73, CD86 and CD304 are aberrantly (over)expressed in a substantial percentage of BCP-ALL patients and that their expression profile remains relatively stable early after starting therapy, supporting their potential contribution to improved MRD analysis by flow cytometry., EM5 and MN5 were supported by the Czech Republic national BCP-ALL MRD grant AZV, no. 15-28525A. ŁS1 and TS7 were supported by the grant from the National Center of Research and Development Strategmed III PersonALL (No. 304586/5/NCBR/2017), internal grant from the Medical University of Silesia and by Iskierka Foundation (Katowice, Poland). PT2, TS7 and ŁS1 were financially supported by ERA-NET PrioMedChild project (no. 40-41800-98-027). Part of this research was performed within the framework of the Erasmus Postgraduate School Molecular Medicine.

Chemokines coordinate lung inflammation and fibrosis by acting on chemokine receptors expressed on leukocytes and other cell types. Atypical chemokine receptors (ACKRs) bind, internalize, and degrade chemokines, tuning homeostasis and immune responses. ACKR2 recognizes and decreases the levels of inflammatory CC chemokines. The role of ACKR2 in fibrogenesis is unknown. The purpose of the study was to investigate the role of ACKR2 in the context of pulmonary fibrosis. The effects of ACKR2 expression and deficiency during inflammation and fibrosis were analyzed using a bleomycin-model of fibrosis, ACKR2-deficient mice, bone marrow chimeras, and antibody-mediated leukocyte depletion. ACKR2 was upregulated acutely in response to bleomycin and normalized over time. ACKR2−/− mice showed reduced lethality and lung fibrosis. Bone marrow chimeras showed that lethality and fibrosis depended on ACKR2 expression in pulmonary resident (nonhematopoietic) cells but not on leukocytes. ACKR2−/− mice exhibited decreased expression of tissue-remodeling genes, reduced leukocyte influx, pulmonary injury, and dysfunction. ACKR2−/− mice had early increased levels of CCL5, CCL12, CCL17, and IFNγ and an increased number of CCR2+ and CCR5+ IFNγ-producing γδT cells in the airways counterbalanced by low Th17-lymphocyte influx. There was reduced accumulation of IFNγ-producing γδT cells in CCR2−/− and CCR5−/− mice. Moreover, depletion of γδT cells worsened the clinical symptoms induced by bleomycin and reversed the phenotype of ACKR2−/− mice exposed to bleomycin. ACKR2 controls the CC chemokine expression that drives the influx of CCR2+ and CCR5+ IFNγ-producing γδT cells, tuning the Th17 response that mediated pulmonary fibrosis triggered by bleomycin instillation.

Fetal loss in animals and humans is frequently associated with inflammatory conditions. D6 is a promiscuous chemokine receptor with decoy function, expressed in lymphatic endothelium, that recognizes and targets to degradation most inflammatory CC chemokines. Here, we report that D6 is expressed in placenta on invading extravillous trophoblasts and on the apical side of syncytiotrophoblast cells, at the very interface between maternal blood and fetus. Exposure of D6 −/− pregnant mice to LPS or antiphospholipid autoantibodies results in higher levels of inflammatory CC chemokines and increased leukocyte infiltrate in placenta, causing an increased rate of fetal loss, which is prevented by blocking inflammatory chemokines. Thus, the promiscuous decoy receptor for inflammatory CC chemokines D6 plays a nonredundant role in the protection against fetal loss caused by systemic inflammation and antiphospholipid antibodies.

Toll IL-1R 8/single Ig IL-1-related receptor (TIR8/SIGIRR) is a member of the IL-1R family, expressed by epithelial tissues and immature dendritic cells, and is regarded as a negative regulator of TLR/IL-1R signaling. Tir8-deficient mice were rapidly killed by intranasal administration of low doses of Mycobacterium tuberculosis, despite controlling efficiently the number of viable bacilli in different organs. Tir8−/−-infected mice showed an increased number of neutrophils and macrophages in the lungs; however, mycobacteria-specific CD4 and CD8 T cells were similar in Tir8−/− and Tir8+/+ mice. Exaggerated mortality of Tir8−/− mice was due to massive liver necrosis and was accompanied by increased levels of IL-1β and TNF-α in lung mononuclear cells and serum, as well as by increased production of IL-1β and TNF-α by M. tuberculosis-infected dendritic cells in vitro. Accordingly, blocking IL-1β and TNF-α with a mix of anti-cytokine Abs, significantly prolonged survival of Tir8−/− mice. Thus, TIR8/SIGIRR plays a key role in damping inflammation and tissue damage in M. tuberculosis infection.

TIR8, also known as single Ig IL-1-related receptor, is a member of the IL-1 receptor/Toll-like receptor (TLR) superfamily, which acts as an intracellular decoy for components of the signaling pathway. Here we report that Tir8 has a unique pattern of expression, which includes mucosal tissues and dendritic cells (DC). Tir8 -deficient DC showed increased cytokine production in response to TLR agonists (lipopolysaccharide, CpG oligodeoxynucleotides). Tir8 -deficient mice had normal susceptibility to systemic lipopolysaccharide toxicity and to i.p. or s.c. inflammation. However, Tir8 -deficient mice were more susceptible to intestinal inflammation. Thus, TIR8 represents a negative pathway of regulation of the IL-1 receptor/TLR system, expressed in epithelial cells and DC, crucial for tuning inflammation in the gastrointestinal tract.