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Allogeneic hematopoietic stem cell transplantation (HSCT) represents the best therapeutic option for many patients with acute myeloid leukemia (AML). However, relapse remains the main cause of mortality after transplantation. The detection of measurable residual disease (MRD) by multiparameter flow cytometry (MFC) in AML, before and after HSCT, has been described as a powerful predictor of outcome. Nevertheless, multicenter and standardized studies are lacking. A retrospective analysis was performed, including 295 AML patients undergoing HSCT in 4 centers that worked according to recommendations from the Euroflow consortium. Among patients in complete remission (CR), MRD levels prior to transplantation significantly influenced outcomes, with overall (OS) and leukemia free survival (LFS) at 2 years of 76.7% and 67.6% for MRD-negative patients, 68.5% and 49.7% for MRD-low patients (MRD < 0.1), and 50.5% and 36.6% for MRD-high patients (MRD ≥ 0.1) (p < 0.001), respectively. MRD level did influence the outcome, irrespective of the conditioning regimen. In our patient cohort, positive MRD on day +100 after transplantation was associated with an extremely poor prognosis, with a cumulative incidence of relapse of 93.3%. In conclusion, our multicenter study confirms the prognostic value of MRD performed in accordance with standardized recommendations.

Background: Evaluation of MRD is standard in patients with AML. However, the role of decentralized MRD assessment for risk stratification in AML remains largely unknown, and so it does which methodological aspects are critical to empower the evaluation of MRD with prognostic significance, particularly if using MFC. Aim: To evaluate the role of decentralized MRD assessment using MFC for risk stratification and putative treatment individualization of patients with AML. Methods: This study was performed on 1,076 AML patients in complete remission (CR) after 7+3 induction chemotherapy, in whom MRD was evaluated by MFC in local laboratories over a period of 20 years in the PETHEMA group. We conducted a survey of technical aspects of MFC based MRD testing in the laboratories of the 60 participating Hospitals, to determine the impact of methodological heterogeneity in the prognostic value of MFC. Results: We first investigated the most effective MRD cutoff to stratify patients' risk at first remission. Patients were segmented into progressively higher cutoffs, starting at 0.01% followed by 0.05%, 0.1%, 0.5% and 1%. Our results showed that 0.1% reached higher statistical significance to discriminate patients with different relapse-free survival (RFS, HR: 0.77; P = .001) and overall survival (OS, HR: 0.73; P = .001). In multivariate analyses together with patients' age, WBC, genetic risk and post-consolidation therapy, MRD status was selected as an independent prognostic factor for OS. To further define the utility of "real-world" MRD assessment using MFC in risk stratification of AML, recursive partitioning was performed using the prognostic and treatment related factors selected in the multivariate Cox model for OS. Of the four variables evaluated, hematopoietic stem cell transplantation (HSCT, regardless of autologous or allogeneic source) vs no transplant emerged as the best single discriminator for OS, followed by genetic risk, age and MRD status. There were two branching points defined by MRD status; the first in patients ≤60 years with intermediate genetic risk who were not transplanted and the second in patients with adverse genetics who were not transplanted, in whom Forty-nine of the 60 hospitals (82%) responded to the survey on questions regarding the measurement of MRD using MFC in the PETHEMA LMA 1999, 2007 and 2010 protocols, providing information corresponding to 966 of the 1,076 (90%) patients regarding the number of markers, preparation of samples, instruments, approach (ie, LAIP, DfN or LAIP+DfN), number of cells to define a cluster, etc. The survey revealed significant heterogeneity intra- and inter-protocols that reflected improvement in MFC assessment of MRD over time, in the absence of harmonization nor standardization at the national level. Accordingly, we investigated if the heterogeneity in methodological, interpretation and reporting aspects of MFC based MRD testing were hampering its ability to predict outcome independently of other patient and treatment related factors. Strikingly, our results showed that except for the denominator used to calculate MRD burden (ie, total nucleated cells vs leukocytes), lack of standardization in all other parameters had an impact on the ability of MFC to predict outcomes in AML (Figure). Namely, panels with ≤4 markers or ≤2 combinations failed to identify patients with significantly different RFS according to MRD status, and MFC-based MRD monitoring was prognostic only when >500,000 cells were measured. Only MRD assessment using patient-specific panels was predictive of outcome. Conclusions: We report here one of the largest studies investigating the role of MRD monitoring using MFC. Our results confirmed that detection of MRD identifies patients in CR/CRi with inferior survival, but uncovered that decentralized MRD testing lacks significance when compared to other baseline risk factors and in the context of risk-adapted post-consolidation strategies. Thus, while this study demonstrated that "real-world" decentralized assessment of MRD using MFC does provide prognostic information in AML patients at first remission, our results question its readiness for risk stratification towards clinical decisions outside trials, at least until adequate standardization of this technique is achieved. Figure Disclosures Paiva: SkylineDx: Consultancy; Takeda: Consultancy, Honoraria, Research Funding; Roche: Research Funding; Adaptive: Honoraria; Amgen: Honoraria; Janssen: Consultancy, Honoraria; Karyopharm: Consultancy, Honoraria; Kite: Consultancy; Celgene: Consultancy, Honoraria, Research Funding, Speakers Bureau; Sanofi: Consultancy, Honoraria, Research Funding. Alonso Dominguez:Celgene: Research Funding; Incyte: Research Funding; Pfizer: Research Funding. Martinez-Lopez:Janssen: Speakers Bureau; Altum: Membership on an entity's Board of Directors or advisory committees, Patents & Royalties; Hosea: Membership on an entity's Board of Directors or advisory committees, Patents & Royalties; Roche: Speakers Bureau; Amgen: Speakers Bureau; Takeda: Speakers Bureau; Vivia Biotech: Honoraria; Novartis: Research Funding; BMS: Research Funding, Speakers Bureau; Incyte: Research Funding, Speakers Bureau. Sossa:Astellas: Honoraria; Roche: Honoraria; Takeda: Honoraria; Novo: Honoraria. San-Miguel:Roche, AbbVie, GlaxoSmithKline, and Karyopharm: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb, Celgene, Novartis, Takeda, Amgen, MSD, Janssen, and Sanofi: Consultancy, Membership on an entity's Board of Directors or advisory committees.

The role of decentralized assessment of measurable residual disease (MRD) for risk stratification in acute myeloid leukemia (AML) remains largely unknown, and so it does which methodological aspects are critical to empower the evaluation of MRD with prognostic significance, particularly if using multiparameter flow cytometry (MFC). We analyzed 1076 AML patients in first remission after induction chemotherapy, in whom MRD was evaluated by MFC in local laboratories of 60 Hospitals participating in the PETHEMA registry. We also conducted a survey on technical aspects of MRD testing to determine the impact of methodological heterogeneity in the prognostic value of MFC. Our results confirmed the recommended cutoff of 0.1% to discriminate patients with significantly different cumulative-incidence of relapse (-CIR- HR:0.71, P, This study was supported by the Centro de Investigación Biomédica en Red – Área de Oncología - del Instituto de Salud Carlos III (CIBERONC; CB16/12/00369, CB16/12/00233, CB16/12/00284 and CB16/12/00400), Instituto de Salud Carlos III/Subdirección General de Investigación Sanitaria (FIS No. PI16/01661, PI16/00517 and PI18/01946), Gerencia Regional de Salud de CyL (GRS 1346/A/16) and the Plan de Investigación de la Universidad de Navarra (PIUNA 2014-18). This study was supported internationally by the Cancer Research UK, FCAECC and AIRC under the Accelerator Award Program EDITOR.

Artificial intelligence methods may help in unveiling information that is hidden in high-dimensional oncological data. Flow cytometry studies of haematological malignancies provide quantitative data with the potential to be used for the construction of response biomarkers. Many computational methods from the bioinformatics toolbox can be applied to these data, but they have not been exploited in their full potential in leukaemias, specifically for the case of childhood B-cell Acute Lymphoblastic Leukaemia. In this paper, we analysed flow cytometry data that were obtained at diagnosis from 56 paediatric B-cell Acute Lymphoblastic Leukaemia patients from two local institutions. Our aim was to assess the prognostic potential of immunophenotypical marker expression intensity. We constructed classifiers that are based on the Fisher&rsquo, s Ratio to quantify differences between patients with relapsing and non-relapsing disease. We also correlated this with genetic information. The main result that arises from the data was the association between subexpression of marker CD38 and the probability of relapse.

Acute myeloid leukemia with myelodysplasia‐related changes (AML‐MRC) are poor outcome leukemias. Its diagnosis is based on clinical, cytogenetic, and cytomorphologic criteria, last criterion being sometimes difficult to assess. A high frequency of ASXL1 mutations have been described in this leukemia. We sequenced ASXL1 gene mutations in 61 patients with AML‐MRC and 46 controls with acute myeloid leukemia without other specifications (AML‐NOS) to identify clinical, cytomorphologic, and cytogenetic characteristics associated with ASXL1 mutational status. Mutated ASXL1 (ASXL1+) was observed in 31% of patients with AML‐MRC compared to 4.3% in AML‐NOS. Its presence in AML‐MRC was associated with older age, a previous history of myelodysplastic syndrome (MDS) or myelodysplastic/myeloproliferative neoplasms (MDS/MPN), leukocytosis, presence of micromegakaryocytes in bone marrow, lower number of blasts in bone marrow, myelomonocytic/monocytic morphological features and normal karyotype. ASXL1 mutation was not observed in patients with myelodysplastic syndrome‐related cytogenetic abnormalities or TP53 mutations. Differences in terms of overall survival were found only in AML‐MRC patients without prior MDS or MDS/MPN and with intermediate‐risk karyotype, having ASXL1+ patients a worst outcome than ASXL1−. We conclude that the ASXL1 mutation frequency is high in AML‐MRC patients being its presence associated with specific characteristics including morphological signs of dysplasia. This association raises the possible role of ASXL1 as a surrogate marker in AML‐MRC, which could facilitate the diagnosis of patients within this group when the karyotype is normal, and especially when the assessment of multilineage dysplasia morphologically is difficult. This mutation could be used as a worst outcome marker in de novo AML‐MRC with intermediate‐risk karyotype., The ASXL1 mutation frequency is high in AML‐MRC patients being its presence associated with specific characteristics, including morphological signs of dysplasia. This association raises the possible role of ASXL1 as a surrogate marker in AML‐MRC, which could facilitate the diagnosis of patients within this group when the karyotype is normal, and especially when the assessment of multilineage dysplasia morphologically is difficult. This mutation could be used as a worst outcome marker in de novo AML‐MRC with intermediate‐risk karyotype.

Purpose: The biologically active metabolite of vitamin D3, 1,25-dihydroxyvitamin D3 (vit D), has immunoregulatory properties via binding vitamin D receptor (VDR). In a prospective trial, we previously reported a reduction in the incidence of chronic GvHD (cGvHD) among patients who received vit D after allogeneic stem cell transplantation (allo-HSCT; Clinical Trials.gov: NCT02600988). Here we analyze the role of patients and donors' VDR SNPs on the immunomodulatory effect of vit D. Patients and Methods: Patients undergoing allo-HSCT were included in a prospective phase I/II clinical trial (Alovita) in three consecutive cohorts: control (without vit D), low-dose (1,000 IU/day), and high-dose (5,000 IU/day) groups. Vit D was given from day −5 until +100 after transplant. Genotyping of four SNPs of the VDR gene, FokI, BsmI, ApaI, and TaqI, were performed using TaqMan SNP genotyping assays. Results: We observed a decrease in the incidence of overall cGvHD at 1 year after allo-HSCT depending on the use or not of vit D among patients with FokI CT genotype (22.5% vs 80%, P = 0.0004) and among those patients without BsmI/ApaI/TaqI ATC haplotype (22.2% vs 68.8%, P = 0.0005). In a multivariate analysis, FokI CT genotype significantly influenced the risk of cGvHD in patients treated with vit D as compared with the control group (HR 0.143, Pinteraction < 0.001). Conclusions: Our results show that the immunomodulatory effect of vit D depends on the VDR SNPs, and patients carrying the FokI CT genotype display the highest benefit from receiving vit D after allo-HSCT.

Although hematopoietic and immune system show high levels of the cannabinoid receptor CB2, the potential effect of cannabinoids on hematologic malignancies has been poorly determined. Here we have investigated their anti-tumor effect in multiple myeloma (MM). We demonstrate that cannabinoids induce a selective apoptosis in MM cell lines and in primary plasma cells of MM patients, while sparing normal cells from healthy donors, including hematopoietic stem cells. This effect was mediated by caspase activation, mainly caspase-2, and was partially prevented by a pan-caspase inhibitor. Their pro-apoptotic effect was correlated with an increased expression of Bax and Bak, a decrease of Bcl-xL and Mcl-1, a biphasic response of Akt/PKB and an increase in the levels of ceramide in MM cells. Inhibition of ceramide synthesis partially prevented apoptosis, indicating that these sphingolipids play a key role in the pro-apoptotic effect of cannabinoids in MM cells. Remarkably, blockage of the CB2 receptor also inhibited cannabinoid-induced apoptosis. Cannabinoid derivative WIN-55 enhanced the anti-myeloma activity of dexamethasone and melphalan overcoming resistance to melphalan in vitro. Finally, administration of cannabinoid WIN-55 to plasmacytoma-bearing mice significantly suppressed tumor growth in vivo. Together, our data suggest that cannabinoids may be considered as potential therapeutic agents in the treatment of MM.

The relevance of the immune system in cancer has long been studied. Autologous adoptive T cell therapies, based on the use of tumor infiltrating lymphocytes (TILs), have made great progress in recent years for the treatment of solid tumors, especially melanoma. However, further work is needed to isolate tumor-reactive T cells among patients diagnosed with hematologic malignancies. The dynamics of the interaction between T cells and antigen presenting cells (APC) dictate the quality of the immune responses. While stable joints between target cells and T lymphocytes lead to the induction of T cell activation and immune response, brief contacts contribute to the induction of immune-tolerance. Taking advantage of the strong interaction between target cell and activated T-cells, we show the feasibility to identify and isolate tumor-specific cytotoxic T lymphocytes (CTLs) from acute myeloid leukemia (AML) patients by flow cytometry. Using this technology, CTLs bound through T cell receptor (TCR) to tumor cells can be identified in peripheral blood and bone marrow and subsequently selected and isolated by FACS-based cell sorting. These CTLs display higher percentage of effector cells and marked cytotoxic activity against AML blasts. In conclusion, we have developed a new procedure to identify and select specific cytotoxic T cells in patients diagnosed with acute myeloid leukemia., EG-G was supported by Instituto de Salud Carlos III (PFIS- FI12/00189). JB-G was supported by the SEHH. This work was supported by the Instituto de Salud Carlos III (ISCIII PI14/02074, PI11/02366, and PI17/02177), integrated in the national I+D+i 2013–2016 and co-funded by European Union (ERDF/ESF, Investing in your future) and the CIBER (CB16/12/00480).

Chronic graft-versus-host disease (cGVHD) remains a major cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation (HSCT). Aim is to identify risk factors for the development of cGVHD in a multicenter setting. Patients transplanted between 2000 and 2006 were analyzed (n = 820). Donors were HLA-identical siblings (57%), matched unrelated donors (30%), and HLA-A, B or DR antigen mismatched (13%). Reduced intensity conditioning (RIC) was given to 65% of patients. Overall incidence of cGVHD was 46% for patients surviving more than 100 days after HSCT (n = 747). Older patient age [HR 1.15, p < 0.001], prior acute GVHD [1.30, p = 0.024], and RIC [1.36, p = 0.028] increased overall cGVHD. In addition, RIC [4.85, p < 0.001], prior aGVHD [2.14, p = 0.001] and female donor to male recipient [1.80, p = 0.008] increased the risk of severe cGVHD. ATG had a protective effect for both overall [0.41, p < 0.001] and severe cGVHD [0.20, p < 0.001]. Relapse-free survival (RFS) was impaired in patients with severe cGVHD. RIC, prior aGVHD, and female-to-male donation increase the risk of severe cGVHD. ATG reduces the risk of all grades of cGVHD without hampering RFS. GVHD prophylaxis may be tailored according to the risk profile of patients.

PRAME is a tumor associated antigen (TAA) of particular interest since it is widely expressed by lymphoid and myeloid malignancies. Several studies have associated high PRAME RNA levels with good prognosis in acute myeloid leukemia (AML). PRAME expression is regulated at the epigenetic level. For this reason inhibitors of DNA methylation, such as 5-azacytidine, can modulate the expression of this TAAs. In the current study we analyzed the effect of 5-azaC on the expression of PRAME in blasts versus CD34+ cells from healthy donors in an attempt to increase its expression, thus inducing a potential target for therapeutic strategies.

Current graft-versus-host disease (GVHD) inhibition approaches lead to abrogation of pathogen-specific T-cell responses. We propose an approach to inhibit GVHD without hampering immunity against pathogens: in vitro depletion of alloreactive T cells with the preoteasome inhibitor bortezomib. We show that PBMCs stimulated with allogeneic cells and treated with bortezomib greatly reduce their ability to produce IFN-γ when re-stimulated with the same allogeneic cells, but mainly preserve their ability to respond to citomegalovirus stimulation. Unlike in vivo administration of immunosuppressive drugs or other strategies of allodepletion, in vitro allodepletion with bortezomib maintains pathogen-specific T cells, representing a promising alternative for GVHD prophylaxis. © 2011 Elsevier Ltd., Belén Blanco was supported by a fellowship from the Fondo de Investigación Sanitaria and by a grant of Gerencia Regional de Salud de Castilla y León.

Purpose: We describe the results of a prospective multicenter phase I/II trial evaluating the impact of the use of vitamin D (VitD) from day −5 to +100 on the outcome of patients undergoing allogeneic transplantation (EudraCT: 2010-023279-25; ClinicalTrials.gov: NCT02600988). Experimental Design: A total of 150 patients were included in three consecutive cohorts of 50 patients each group: control group (CG, not receive VitD); low-dose group (LdD, received 1,000 IU VitD daily); and high-dose group (HdD, 5,000 IU VitD daily). We measured levels of VitD, cytokines, and immune subpopulations after transplantation. Results: No significant differences were observed in terms of cumulative incidence of overall and grades 2–4 acute GVHD in terms of relapse, nonrelapse mortality, and overall survival. However, a significantly lower cumulative incidence of both overall and moderate plus severe chronic GVHD (cGVHD) at 1 year was observed in LdD (37.5% and 19.5%, respectively) and HdD (42.4% and 27%, respectively) as compared with CG (67.5% and 44.7%, respectively; P < 0.05). In multivariable analysis, treatment with VitD significantly decreased the risk of both overall (for LdD: HR = 0.31, P = 0.002; for HdD: HR = 0.36, P = 0.006) and moderate plus severe cGVHD (for LdD: HR = 0.22, P = 0.001; for HdD: HR = 0.33, P = 0.01). VitD modified the immune response, decreasing the number of B cells and naïve CD8 T cells, with a lower expression of CD40L. Conclusions: This is the first prospective trial that analyzes the effect of VitD postransplant. We observed a significantly lower incidence of cGVHD among patients receiving VitD. Interestingly, VitD modified the immune response after allo-SCT. Clin Cancer Res; 22(23); 5673–81. ©2016 AACR.

It is established that hematopoietic stem cells (HSC) in the hypoxic bone marrow have adapted their metabolism to oxygen-limiting conditions. This adaptation includes suppression of mitochondrial activity, induction of anerobic glycolysis, and activation of hypoxia-inducible transcription factor 1α (Hif1α)-dependent gene expression. During progression of hematopoiesis, a metabolic switch towards mitochondrial oxidative phosphorylation is observed, making this organelle essential for determining cell fate choice in bone marrow. However, given that HSC metabolism is essentially oxygen-independent, it is still unclear whether functional mitochondria are absolutely required for their survival. To assess the actual dependency of these undifferentiated cells on mitochondrial function, we have performed an analysis of the hematopoiesis in a mouse mutant, named SDHD-ESR, with inducible deletion of the mitochondrial protein-encoding SdhD gene. This gene encodes one of the subunits of the mitochondrial complex II (MCII). In this study, we demonstrate that, in contrast to what has been previously established, survival of HSC, and also myeloid and B-lymphoid progenitors, depends on proper mitochondrial activity. In addition, gene expression analysis of these hematopoietic lineages in SDHD-ESR mutants calls into question the proposed activation of Hif1α in response to MCII dysfunction. Ministerio de Ciencia e Innovación SAF2009-06970 Junta de Andalucía CTS-4589 Instituto de Salud Carlos III PI-0355-2013

Background aims Mesenchymal stromal cells (MSCs) are multipotent stem cells with immunosuppressive properties. Nevertheless, it has been previously reported that MSCs might also trigger the immune response. We studied whether MSCs may act as carriers, capturing antigens that can be endocytosed by antigen-presenting cells later on. Methods We measured the cellular uptake of mannose receptor-mediated fluid phase macropinocytosis, assessed as cellular uptake of fluorescein isothiocyanate-dextran, and PKH-67-labeled cell lysates as a surrogate marker for antigen capture among dendritic cells (DCs, positive control), T lymphocytes (negative control) and MSCs. Results All experiments confirmed that MCSs displayed pinocytic and endocytic capacities, which were lower than those observed for DCs but significantly higher than those observed for T cells. We also demonstrated that MSCs release previously endocytosed antigens, which subsequently can be captured by DCs. Conclusions MSCs have the ability to capture and release antigens.

This is an open-access paper., [Background]: We have previously shown that bortezomib induces a depletion of alloreactive T cells and allows the expansion of T cells with suppressive properties. In the current study, we analyzed the potential synergistic effect of bortezomib in conjunction with sirolimus in order to reducegraft- versus-host disease without hampering graft-versus-leukemia effect in the allogeneic transplant setting. [Design and Methods]: We evaluated the effect of sirolimus, bortezomib or the combination of both in the proliferation and activation of in vitro stimulated T lymphocytes. Pathways involved in this synergy were also analyzed using Western blot assays. Finally, BALB/c mice receiving C57BL/6 allogeneic donor bone marrow with splenocytes were used to measure in vivo the effect of this novel combination on the risk of graft-versus-host disease. [Results]: The combination of both drugs synergistically inhibited both activation and proliferation of stimulated T cells. Also, the production of Th1 cytokines (IFN γ, IL-2 and TNF) was significantly inhibited. This effect was due, at least in part, to the inhibition of Erk and Akt phosphorylation. In vivo, the combination reduced the risk of graft-versus-host disease without hampering graft-versus-leukemia effect, as shown in mice receiving graft-versus-host disease prophylaxis with sirolimus plus bortezomib being infused with tumor WEHI cells plus C57BL/6 donor BM and splenocytes. [Conclusions]: The current study reveals a synergistic effect of the combination sirolimus and bortezomib to prevent graft-versus-host disease while maintaining the graft-versus-leukemia effect., Supported by a grant Rio Hortega (code: CM10/00161) from the Instituto de Salud Carlos III and grant PI080047 from FIS.

Cytokine genes are targets of multiple epigenetic mechanisms in T lymphocytes. 5-azacytidine (5-azaC) is a nucleoside-based DNA methyltransferase inhibitor that induces demethylation and gene reactivation. In the current study, we analyzed the effect of 5-azaC in T-cell function and observed that 5-azaC inhibits T-cell proliferation and activation, blocking cell cycle in the G0 to G1 phase and decreasing the production of proinflammatory cytokines such as tumor necrosis factor-α and interferon-γ. This effect was not attributable to a proapoptotic effect of the drug but to the down-regulation of genes involved in T-cell cycle progression and activation such as CCNG2, MTCP1, CD58, and ADK and up-regulation of genes that induce cell-growth arrest, such as DCUN1D2, U2AF2, GADD45B, or p53. A longer exposure to the drug leads to demethylation of FOXP3 promoter, overexpression of FOXP3, and expansion of regulatory T cells. Finally, the administration of 5-azaC after transplantation prevented the development of graft-versus-host disease, leading to a significant increase in survival in a fully mismatched bone marrow transplantation mouse model. In conclusion, the current study shows the effect of 5-azaC in T lymphocytes and illustrates its role in the allogeneic transplantation setting as an immunomodulatory drug, describing new pathways that must be explored to prevent graft-versus-host disease.

Producción Científica, Background In vitro depletion of alloreactive T cells using the proteasome inhibitor bortezomib is a promising approach to prevent graft-versus-host disease after allogeneic stem cell transplantation. We have previously described the ability of bortezomib to selectively eliminate alloreactive T cells in a mixed leukocyte culture, preserving non-activated T cells. Due to the role of regulatory T cells in the control of graft versus host disease, in the current manuscript we have analyzed the effect of bortezomib in regulatory T cells.Design and Methods Conventional or regulatory CD4+ T cells were isolated with immunomagnetic microbeads based on the expression of CD4 and CD25. The effect of bortezomib on T-cell viability was analyzed by flow cytometry using 7-amino-actinomycin D staining. To investigate the possibility of obtaining an enriched regulatory T-cell population in vitro with the use of bortezomib, CD4+ T cells were cultured during four weeks in the presence of anti-CD3 and anti-CD28 antibodies, IL-2 and bortezomib. The phenotype of these long-term cultured cells was studied, analyzing the expression of CD25, CD127 and FOXP3 by flow cytometry, and mRNA levels were determined by RT-PCR. Their suppressive capacity was assessed in co-culture experiments, analyzing proliferation and IFN-γ and CD40L expression of stimulated responder T cells by flow cytometry.Results We observed that naturally occurring CD4+CD25+ regulatory T cells are resistant to the pro-apoptotic effect of bortezomib. Furthermore, we found that long-term culture of CD4+ T cells in the presence of bortezomib promotes the emergence of a regulatory T-cell population that significantly inhibits proliferation, IFN-γ production and CD40L expression among stimulated effector T cells.Conclusions These results reinforce the proposal of using bortezomib in the prevention of graft versus host disease and, moreover, in the generation of regulatory T-cell populations, that could be used in the treatment of multiple T-cell mediated diseases.

Frequency of additional chromosomal abnormalities in chronic myeloid leukemia (CML) is estimated to be 7% in chronic phase and increases to 40–70% in advanced disease. Progression of CML from chronic phase to accelerated phase or blast crisis is often associated with secondary chromosomal aberrations. We report an exceptional case of CML as debut in lymphoblastic blast crisis and a subsequent progression in myeloblastic blast crisis with rare cytogenetic abnormalities.