Long-term safety and efficacy of lentiviral hematopoietic stem/progenitor cell gene therapy for Wiskott-Aldrich syndrome.

Patients with Wiskott-Aldrich syndrome (WAS) lacking a human leukocyte antigen-matched donor may benefit from gene therapy through the provision of gene-corrected, autologous hematopoietic stem/progenitor cells. Here, we present comprehensive, long-term follow-up results (median follow-up, 7.6 years) (phase I/II trial no. NCT02333760 ) for eight patients with WAS having undergone phase I/II lentiviral vector-based gene therapy trials (nos. NCT01347346 and NCT01347242 ), with a focus on thrombocytopenia and autoimmunity. Primary outcomes of the long-term study were to establish clinical and biological safety, efficacy and tolerability by evaluating the incidence and type of serious adverse events and clinical status and biological parameters including lentiviral genomic integration sites in different cell subpopulations from 3 years to 15 years after gene therapy. Secondary outcomes included monitoring the need for additional treatment and T cell repertoire diversity. An interim analysis shows that the study meets the primary outcome criteria tested given that the gene-corrected cells engrafted stably, and no serious treatment-associated adverse events occurred. Overall, severe infections and eczema resolved. Autoimmune disorders and bleeding episodes were significantly less frequent, despite only partial correction of the platelet compartment. The results suggest that lentiviral gene therapy provides sustained clinical benefits for patients with WAS.

Revisiting the initial diagnosis and blood staging of mycosis fungoides and Sézary syndrome with the KIR3DL2 marker.

BACKGROUND: The early diagnosis of Sézary syndrome (SS) is challenging. Loss of CD7 and CD26 expression on CD4+ T cells is the currently used criterion in the initial diagnosis and staging of patients with SS. OBJECTIVES: Our aim was to evaluate the respective value of CD26, CD7 and KIR3DL2 expression on CD4+ T cells and total lymphocytes at initial diagnosis of SS. METHODS: This prospective study included 254 patients with clinical features consistent with cutaneous T-cell lymphoma seen at our institution between March 2014 and February 2019. Peripheral blood analysis by flow cytometry was performed for each patient at the time of diagnosis and during follow-up. The diagnosis of SS was based on ISCL/EORTC criteria. RESULTS: The presence of KIR3DL2+ Sézary cells (SCs) ≥ 200 µL-1 correlated with the diagnosis of SS, with sensitivity of 88·6% and specificity of 96·3%. All 154 patients with either inflammatory skin disease or other haematological disease had KIR3DL2+ cells < 200 µL-1 , while eight of them had CD4+ CD26- T cells ≥ 1000 µL-1 . Of five patients with SS and lymphopenia, four had CD4+ CD7- T cells < 1000 µL-1 and three had CD4+ CD26- T cells < 1000 µL-1 . However, all of them had KIR3DL2+ CD4+ T cells ≥ 200 µL-1 . Among patients with available samples during evolution, all B1-staged patients with ≥ 200 µL-1 KIR3DL2+ SCs at diagnosis evolved to B2 stage within 7 months. CONCLUSIONS: KIR3DL2 expression on T cells is highly specific and helps the early diagnosis of SS, especially in those patients with lymphopenia. What's already known about this topic? In the ISCL/EORTC cutaneous T-cell lymphoma (CTCL) categorization of blood involvement (B0-B2), B2 is defined as a T-cell receptor clonal rearrangement in blood, associated with high blood-smear Sézary cell (SC) count. Flow cytometry was developed to circumvent interobserver variability of SC manual counts; however, it mostly relies on detection of cells lacking CD7 and/or CD26 expression. We previously reported the reliability of KIR3DL2 as the first positive SC marker. What does this study add? Based on our analysis of 254 patients, we propose that KIR3DL2 be added to the ISCL/EORTC criteria for initial diagnosis of Sézary syndrome (SS) and B2 staging. This marker improved sensitivity of SS B2-stage CTCL diagnosis with a specificity > 95%, especially for patients with lymphopenia. We found KIR3DL2 helped early diagnosis of SS and was more reliable than CD26 in assessing blood tumour burden during therapy. What is the translational message? SC quantification is the major means of staging at initial diagnosis and monitoring blood tumour burden in a clinical trials setting. We recommend using a threshold value of KIR3DL2+ SCs ≥ 200 µL-1 or KIR3DL2+ SCs/lymphocytes ≥ 10% in the diagnostic criteria of SS and propose a novel algorithm for CTCL B2 blood staging.

Recovery of central memory and naive peripheral T cells in Follicular Lymphoma patients receiving rituximab-chemotherapy based regimen.

Preclinical models and clinical studies have shown that anti-CD20-based treatment has multifaceted consequences on T-cell immunity. We have performed a prospective study of peripheral T-cell compartment in FL patients, all exhibiting high tumor burden and receiving rituximab-chemotherapy-based regimen (R-CHOP). Before treatment, FL patients harbor low amounts of peripheral naive T cells, but high levels of CD4+ TEM, CD4+ Treg and CD8+ TEMRA subsets and significant amounts of CD38+ HLA-DR+ activated T cells. A portion of these activated/differentiated T cells also expressed PD-1 and/or TIGIT immune checkpoints. Hierarchical clustering of phenotyping data revealed that 5/8 patients with only a partial response to R-CHOP induction therapy or with disease progression segregate into a group exhibiting a highly activated/differentiated T cell profile and a markedly low proportion of naive T cells before treatment. Rituximab-based therapy induced a shift of CD4+ and CD8+ T cells toward a central memory phenotype and of CD8+ T cells to a naive phenotype. In parallel, a decrease in the number of peripheral T cells expressing both PD-1 and TIGIT was detected. These observations suggest that the standard rituximab-based therapy partially reverts the profound alterations observed in T-cell subsets in FL patients, and that blood T-cell phenotyping could provide a better understanding of the mechanisms of rituximab-based treatment.

Impact of genomic risk factors on survival after haematopoietic stem cell transplantation for patients with acute leukaemia.

The EBMT risk score is an established tool successfully used in the prognosis of survival post-HSCT and is applicable for a range of haematological disorders. One of its main advantages is that score generation involves summation of clinical parameters that are available pretransplant. However, the EBMT risk score is recognized as not being optimal. Previous analyses, involving patients with various diagnoses, have shown that non-HLA gene polymorphisms influence outcome after allogeneic HSCT. This study is novel as it focuses only on patients having acute leukaemia (N = 458) and attempts to demonstrate how non-HLA gene polymorphisms can be added to the EBMT risk score in a Cox regression model to improve prognostic ability for overall survival. The results of the study found that three genetic factors improved EBMT risk score. The presence of MAL (rs8177374) allele T in the patient, absence of glucocorticoid receptor haplotype (consisting of rs6198, rs33389 and rs33388) ACT in the patient and absence of heat-shock protein 70-hom (+2437) (rs2227956) allele C in the patient were associated with decreased survival time. When compared to the EBMT risk score, the scores combining EBMT risk score with the genetic factors had an improved correlation with clinical outcome and better separation of risk groups. A bootstrapping technique, involving repeated testing of a model using multiple validation sets, also revealed that the newly proposed model had improved predictive value when compared to the EBMT risk score alone. Results support the view that non-HLA polymorphisms could be useful for pretransplant clinical assessment and provide evidence that polymorphisms in the recipient genotype may influence incoming donor cells, suppressing the initiation of the graft versus leukaemia effect and reducing survival.

Resetting the immune response after autologous hematopoietic stem cell transplantation for autoimmune diseases.

Autologous hematopoietic stem cell transplantation (AHSCT) is currently investigated as treatment for severe and refractory autoimmune diseases, such as multiple sclerosis (MS), systemic sclerosis (SSc), Crohn's disease (CD) and systemic lupus erythematosus. Randomized clinical trials in MS, SSc and CD have shown the efficacy of AHSCT to promote control of disease activity and progression, when compared to conventional treatment. The use of high dose immunosuppressive conditioning is essential to eliminate the autoimmune repertoire, and the re-infusion of autologous hematopoietic stem cells avoids long-term leucopenia by reconstitution of both immune and hematological systems. Recent studies showed that AHSCT is able to deplete the autoimmune compartment and further promote the formation of a new auto-tolerant immune repertoire, reducing the inflammatory milieu and leading to long-term clinical remission without any complementary post-graft treatment. Deep knowledge about the mechanisms of action related to AHSCT-induced remission is required for the management of possible post-AHSCT relapse and improvement of clinical protocols. This paper will review the mechanisms enrolled in the immune response resetting promoted by AHSCT in patients with autoimmune diseases.

Predicting survival using clinical risk scores and non-HLA immunogenetics.

Previous studies of non-histocompatibility leukocyte antigen (HLA) gene single-nucleotide polymorphisms (SNPs) on subgroups of patients undergoing allogeneic haematopoietic stem cell transplantation (HSCT) revealed an association with transplant outcome. This study further evaluated the association of non-HLA polymorphisms with overall survival in a cohort of 762 HSCT patients using data on 26 polymorphisms in 16 non-HLA genes. When viewed in addition to an already established clinical risk score (EBMT-score), three polymorphisms: rs8177374 in the gene for MyD88-adapter-like (MAL; P=0.026), rs9340799 in the oestrogen receptor gene (ESR; P=0.003) and rs1800795 in interleukin-6 (IL-6; P=0.007) were found to be associated with reduced overall survival, whereas the haplo-genotype (ACC/ACC) in IL-10 was protective (P=0.02). The addition of these non-HLA polymorphisms in a Cox regression model alongside the EBMT-score improved discrimination between risk groups and increased the level of prediction compared with the EBMT-score alone (gain in prediction capability for EBMT-genetic-score 10.8%). Results also demonstrated how changes in clinical practice through time have altered the effects of non-HLA analysis. The study illustrates the significance of non-HLA genotyping prior to HSCT and the importance of further investigation into non-HLA gene polymorphisms in risk prediction.

SCT for severe autoimmune diseases: consensus guidelines of the European Society for Blood and Marrow Transplantation for immune monitoring and biobanking.

Over the past 15 years, SCT has emerged as a promising treatment option for patients with severe autoimmune diseases (ADs). Mechanistic studies recently provided the proof-of-concept that restoration of immunological tolerance can be achieved by haematopoietic SCT in chronic autoimmunity through eradication of the pathologic, immunologic memory and profound reconfiguration of the immune system, that is, immune 'resetting'. Nevertheless, a number of areas remain unresolved and warrant further investigation to refine our understanding of the underlying mechanisms of action and to optimize clinical SCT protocols. Due to the low number of patients transplanted in each centre, it is essential to adequately collect and analyse biological samples in a larger cohort of patients under standardized conditions. The European society for blood and marrow transplantation Autoimmune Diseases and Immunobiology Working Parties have, therefore, undertaken a joint initiative to develop and implement guidelines for 'good laboratory practice' in relation to procurement, processing, storage and analysis of biological specimens for immune reconstitution studies in AD patients before, during and after SCT. The aim of this document is to provide practical recommendations for biobanking of samples and laboratory immune monitoring in patients with ADs undergoing SCT, both for routine supportive care purposes and investigational studies.

Reconstitution of regulatory T-cell subsets after allogeneic hematopoietic SCT.

Previous studies on regulatory T-cell (Treg) reconstitution after allogeneic hematopoietic SCT (HSCT) have suggested that, within the GVHD process, imbalance between effector T cells and Tregs may be more important than the absolute numbers of circulating Tregs. No study has analyzed naive vs memory Treg reconstitution in a longitudinal cohort with large numbers of patients. The reconstitution of total and subsets of Treg was prospectively analyzed by flow cytometry in 185 consecutive recipients at 3, 6, 12 and 24 months after allogeneic HSCT. The levels of total, naive and memory Tregs increased, mainly within the memory subset, but remained lower than healthy controls up to 2 years after transplantation. Reduced-intensity conditioning and peripheral blood (PBSC) as the source of stem cells were associated with better 3-month reconstitution. In multivariate analysis, PBSC, recipient age ⩽25 and no anti-thymoglobulin in the conditioning regimen were associated with a better Treg reconstitution. Naive Treg long-term reconstitution was mainly influenced by recipient age. Whereas prior acute GVHD impaired Treg reconstitution, Treg subsets (absolute numbers and frequencies relative to CD4(+) T-cell subsets) at 3, 6 and 12 months after HSCT were not associated with the occurrence of a later episode of chronic GVHD.

Oligoclonal expansions of mucosal T cells in Crohn's disease predominate in NKG2D-expressing CD4 T cells.

Crohn's disease (CD) is an inflammatory pathology of the mucosal intestine that results from uncontrolled immune response towards commensal microbes. Clonal expansions of T cells have been found in patients with CD suggesting an antigen-specific stimulation of pathogenic T cells. Here we show, using T-cell receptor repertoire analysis by real-time PCR, that oligoclonal expansions are found in both CD8+ and CD4+ T cells in the blood and intestinal mucosa of CD patients. The majority of CD4+ T-cell-expanded clones are CD4+NKG2D+ T cells. These clonal expansions were found in both inflamed and neighboring healthy tissue and were persisting during the course of the disease. The presence of these CD4+NKG2D+ T-cell clones at the macroscopically normal edge of the surgical resection might be predictive of inflammation relapse post surgery.

Thymus and immune reconstitution after allogeneic hematopoietic stem cell transplantation in humans: never say never again.

Assessment of the host immune status is becoming a key issue in allogeneic hematopoietic stem cell transplantation (allo-HSCT). In the long-term follow-up of these patients, severe post-transplant infections, relapse or secondary malignancies may be directly related to persistent immune defects. In allo-HSCT, T-cell differentiation of donor progenitors within the recipient thymus is required to generate naive recent T-cell emigrants (RTE). These cells account for a durable T-cell reconstitution, generating a diverse T-cell receptor (TCR) repertoire and robust response to infections. It is now possible to quantify the production of RTE by measuring thymic T-cell receptor excision circles or 'TREC' which are small circular DNA produced during the recombination of the genomic segments encoding the TCR alpha chain. Here we discuss the role of thymic function in allo-HSCT. The pre-transplant recipient thymic function correlates with clinical outcome in terms of survival and occurrence of severe infections. Post-transplant, TREC analysis showed that the thymus is a sensitive target to the allogeneic acute graft-versus-host disease (GvHD) reaction but is also prone to recovery in young adult patients. In all, thymus is a key player for the quality of immune reconstitution and clinical outcome after allo-HSCT. Thymic tissue is plastic and it is a future challenge to halt or reverse thymic GVHD therapeutically by acting at the level of T-cell progenitors generation, thymic homing and/or epithelial thymic tissue preservation.

Outcomes, infections, and immune reconstitution after double cord blood transplantation in patients with high-risk hematological diseases.

Double unrelated cord blood transplant (dUCBT) has been used to circumvent cell dose limitation of single UCBT; however, few data are available describing outcomes, infectious disease, and immune recovery. We analyzed 35 consecutive dUCBT recipients with high-risk malignant disorders (n=21) and bone marrow failure syndromes (n=14). Median follow-up was 32 months. Conditioning regimen was myeloablative in 14 and reduced intensity in 21 patients. Median infused nucleated cell dose was 4 × 10(7) /kg. Median time to absolute neutrophil count >0.5 × 10(9) /L was 25 days. Cumulative incidence (CI) of acute grade II-IV graft-versus-host disease was 47%. Estimated overall survival at 2 years was 48%. CI of first viral infections at 1 year was 92%. We observed 49 viral infections in 30 patients, 34 bacterial infections in 19 patients, and 16 fungal or parasitic infections in 12 patients. Lymphocyte subset analyses were performed at 3, 6, 9, and >12 months after dUCBT. Decreased T-cell and B-cell counts with expansion of natural killer cells were observed until 9 months post transplantation. Recovery of thymopoiesis measured by T-cell receptor excision circles was impaired until 9 months after dUCBT, when the appearance of new thymic precursors was observed. Delayed immune recovery and high incidence of infectious complications were observed after dUCBT in patients with high-risk hematological diseases.

Activating KIR genes are associated with CMV reactivation and survival after non-T-cell depleted HLA-identical sibling bone marrow transplantation for malignant disorders.

Combinations of HLA and killer immunoglobulin-like receptors (KIR) may affect outcome in T-cell depleted haematopoietic stem cell transplantation (HSCT). The KIR gene family includes inhibitory (KIR2DL and 3DL) and activating receptors (KIR2DS). Ligands are HLA-C (KIR2D) and HLA-Bw4 (KIR3DL1) for inhibitory KIR and are still unknown for activating KIR. The impact of activating KIR genotypes from donor and recipient is poorly documented in HSCT outcome. Here, HLA and KIR genotypes were determined in 131 pairs from non-T-cell depleted HLA-identical sibling HSCT. No effect of 'missing KIR ligand' was detected on acute graft-versus-host disease (GVHD), relapse, survival or infections even in myeloid malignancies. However, additional activating KIR genes in the donor compared to the recipient's genotype or an identity between donor and recipient activating KIR genotypes was associated with a lower transplant-related mortality (TRM) (P=0.005) and in a multivariate analysis with a better survival (P=0.02, HR=0.28; P=0.013, HR=0.29) and a lower incidence of cytomegalovirus (CMV) reactivation (P=0.009, HR=0.36). These data highlight the impact of donor-activating KIR genes on TRM, overall survival and CMV reactivation in HLA-identical sibling HSCT.

Defective blood dendritic cells in chronic myeloid leukemia correlate with high plasmatic VEGF and are not normalized by imatinib mesylate.

Human blood dendritic cells (DC) comprise plasmacytoid DC (PDC) and myeloid DC (MDC), which both prime antitumor T-cell responses. We prospectively monitored blood DC in 30 chronic myeloid leukemia (CML) patients before and after imatinib mesylate therapy. We found a dramatic reduction in PDC and MDC prior treatment. This reduction was associated with high plasmatic vascular endothelial growth factor (VEGF), a central regulator of angiogenesis which also participates to tumor-associated immune deficiencies. Phenotypic analysis of DC revealed in some patients a deficient expression of BDCA-4/neuropilin-1 on PDC, a molecule involved in angiogenesis and DC-T-cell interactions. High VEGF correlated to an altered Th1/Th2 balance in vivo and shifted PDC-induced T-cell polarization towards Th2 in vitro. Upon imatinib treatment, plasmatic VEGF rapidly decreased and a normal BDCA-4 expression was restored. PDC and MDC increased but did not reach the levels observed in healthy individuals. We conclude that VEGF may be a key player in blood DC deficiency in CML and we show that imatinib inhibits VEGF overproduction. Incomplete recovery of blood DC under imatinib despite VEGF normalization suggests a negative impact of this drug on dendritopoiesis in vivo and may result in a sustained defect in DC-mediated anti-CML responses.

[Natural killer lymphocyte activation in response to stress]. / Récepteurs des lymphocytes natural killer et réponses au stress.

Function of T and natural killer (NK) lymphocytes is tightly controlled by the balance of activating and inhibitory signals. NK receptors belong to different families: KIRs ("Killer cell Immunoglobulin-like Receptor") and ILTs ("Immunoglobulin-like Transcript"), mainly inhibitory which binds to HLA class I alleles; C-type lectin NK receptors such as CD94/NKG2A which is inhibitory and binds to HLA-E; NCR ("Natural Cytotoxicity Receptors") which directly activate NK cells. These include molecules NKp30, NKp44, NKp46 et NKG2D. Cellular stress (viral and bacterial infections, tumours) may modulate NK function by different mechanisms: decrease in HLA class I molecules expression resulting in the lack of engagement of the inhibitory receptors and ultimately NK cell activation; modulation of CD94/NKG2A inhibitory function through expression of peptides presented by HLA-E as for instance from heat shock proteins; NK activation through NCR expression. Among these, NKG2D is an activating receptor expressed by NK cells and subsets of alphabeta and gammadelta and T cells. Major NKG2D ligands in humans are MIC ("MHC class I related") molecules which are stress-inducible during a viral (CMV) or bacterial infection (M. tuberculosis, E. coli). They may also be expressed by tumors. Therefore, they could play a role in activating NK and/or T lymphocyte responses in these conditions.

Differences in MHC-class I presented minor histocompatibility antigens extracted from normal and graft-versus-host disease (GVHD) mice.

Graft-versus-host disease (GVHD) may develop after allogeneic bone marrow transplantation (BMT) between donors and recipients incompatible for minor histocompatibility antigens (mHAg). Here, we examined the possible relationship between tissue-specific distribution of dominant mHAg peptides and specific organ destruction caused by GVHD. In the B6 anti-Balb/b (H-2b) strain combination, a GVHD developed against Balb/b mHAgs. Despite the high number of incompatible mHAgs between these two strains, both cytotoxic T lymphocyte (CTL) response and GVHD could be attributed to a limited number of dominant mHAgs. We studied CTL-defined expression of dominant mHAgs in normal tissues and their GVHD-related modifications. mHAg peptides were prepared by acid elution and reversed-phase high pressure liquid chromatography fractionation from the spleen, liver, gut and skin as GVHD target tissues and from the heart and kidney as control tissues. Peptidic fractions extracted from normal and GVHD tissues were incubated with RMA-S targets and analysed using bulk B6 anti-Balb/b CTL. In each tissue several fractions were recognized with a given pattern of mHAg expression. GVHD induced qualitative and quantitative changes in antigenic peptide expression. Modifications in mHAg presentation during GVHD concerned preferentially GVHD target organs as opposed to non-GVHD target organs. In addition, when immunizing tissues were derived from GVHD mice instead of normal mice, the profile of CTL recognition was different. In conclusion, these data indicate that broad differences could exist in peptide presentation between various normal and GVHD-target organs.