Dicer is selectively important for the earliest stages of erythroid development.

MicroRNAs (miRs) are involved in many aspects of normal and malignant hematopoiesis, including hematopoietic stem cell (HSC) self-renewal, proliferation, and terminal differentiation. However, a role for miRs in the generation of the earliest stages of lineage committed progenitors from HSCs has not been identified. Using Dicer inactivation, we show that the miR complex is not only essential for HSC maintenance but is specifically required for their erythroid programming and subsequent generation of committed erythroid progenitors. In bipotent pre-MegEs, loss of Dicer up-regulated transcription factors preferentially expressed in megakaryocyte progenitors (Gata2 and Zfpm1) and decreased expression of the erythroid-specific Klf1 transcription factor. These results show a specific requirement for Dicer in acquisition of erythroid lineage programming and potential in HSCs and their subsequent erythroid lineage differentiation, and in particular indicate a role for the miR complex in achieving proper balance of lineage-specific transcriptional regulators necessary for HSC multilineage potential to be maintained.

Enhancing Efficacy of TCR-engineered CD4 + T Cells Via Coexpression of CD8α.

Adoptive cell therapy with T cells expressing affinity-enhanced T-cell receptors (TCRs) is a promising treatment for solid tumors. Efforts are ongoing to further engineer these T cells to increase the depth and durability of clinical responses and broaden efficacy toward additional indications. In the present study, we investigated one such approach: T cells were transduced with a lentiviral vector to coexpress an affinity-enhanced HLA class I-restricted TCR directed against MAGE-A4 alongside a CD8α coreceptor. We hypothesized that this approach would enhance CD4 + T-cell helper and effector functions, possibly leading to a more potent antitumor response. Activation of transduced CD4 + T cells was measured by detecting CD40 ligand expression on the surface and cytokine and chemokine secretion from CD4 + T cells and dendritic cells cultured with melanoma-associated antigen A4 + tumor cells. In addition, T-cell cytotoxic activity against 3-dimensional tumor spheroids was measured. Our data demonstrated that CD4 + T cells coexpressing the TCR and CD8α coreceptor displayed enhanced responses, including CD40 ligand expression, interferon-gamma secretion, and cytotoxic activity, along with improved dendritic cell activation. Therefore, our study supports the addition of the CD8α coreceptor to HLA class I-restricted TCR-engineered T cells to enhance CD4 + T-cell functions, which may potentially improve the depth and durability of antitumor responses in patients.

Decreased differentiation of erythroid cells exacerbates ineffective erythropoiesis in beta-thalassemia.

In beta-thalassemia, the mechanism driving ineffective erythropoiesis (IE) is insufficiently understood. We analyzed mice affected by beta-thalassemia and observed, unexpectedly, a relatively small increase in apoptosis of their erythroid cells compared with healthy mice. Therefore, we sought to determine whether IE could also be characterized by limited erythroid cell differentiation. In thalassemic mice, we observed that a greater than normal percentage of erythroid cells was in S-phase, exhibiting an erythroblast-like morphology. Thalassemic cells were associated with expression of cell cycle-promoting genes such as EpoR, Jak2, Cyclin-A, Cdk2, and Ki-67 and the antiapoptotic protein Bcl-X(L). The cells also differentiated less than normal erythroid ones in vitro. To investigate whether Jak2 could be responsible for the limited cell differentiation, we administered a Jak2 inhibitor, TG101209, to healthy and thalassemic mice. Exposure to TG101209 dramatically decreased the spleen size but also affected anemia. Although our data do not exclude a role for apoptosis in IE, we propose that expansion of the erythroid pool followed by limited cell differentiation exacerbates IE in thalassemia. In addition, these results suggest that use of Jak2 inhibitors has the potential to profoundly change the management of this disorder.

Hyperforin down-regulates effector function of activated T lymphocytes and shows efficacy against Th1-triggered CNS inflammatory-demyelinating disease.

Hyperforin (Hyp) is an active compound contained in the extract of Hypericum perforatum, well known for its antidepressant activity. However, Hyp has been found to possess several other biological properties, including inhibitory effects on tumor invasion, angiogenesis, and inflammation. In this paper, we show that treatment with Hyp inhibited IFN-gamma production, with down-regulation of T-box (T-bet; marker of Th1 gene expression) and up-regulation of GATA-3 (marker gene of Th2) on IL-2/PHA-activated T cells. In parallel, we showed a strong down-regulation of the chemokine receptor CXCR3 expression on activated T cells. The latter effect and the down-modulation of matrix metalloproteinase 9 expression may eventually lead to the inhibition of migratory capability and matrix traversal toward the chemoattractant CXCL10 by activated lymphocytes that we observed in vitro. The effect of Hyp was thus evaluated on an animal model of experimental allergic encephalomyelitis (EAE), a classic, Th1-mediated autoimmune disease of the CNS, and we observed that Hyp attenuates the severity of the disease symptoms significantly. Together, these properties qualify Hyp as a putative, therapeutic molecule for the treatment of autoimmune inflammatory disease sustained by Th1 cells, including EAE.

Long-term safety and activity of NY-ESO-1 SPEAR T cells after autologous stem cell transplant for myeloma.

This study in patients with relapsed, refractory, or high-risk multiple myeloma (MM) evaluated the safety and activity of autologous T cells engineered to express an affinity-enhanced T-cell receptor (TCR) that recognizes a peptide shared by cancer antigens New York esophageal squamous cell carcinoma-1 (NY-ESO-1) and L-antigen family member 1 (LAGE-1) and presented by HLA-A*02:01. T cells collected from 25 HLA-A*02:01-positive patients with MM expressing NY-ESO-1 and/or LAGE-1 were activated, transduced with self-inactivating lentiviral vector encoding the NY-ESO-1c259TCR, and expanded in culture. After myeloablation and autologous stem cell transplant (ASCT), all 25 patients received an infusion of up to 1 × 1010 NY-ESO-1 specific peptide enhanced affinity receptor (SPEAR) T cells. Objective response rate (International Myeloma Working Group consensus criteria) was 80% at day 42 (95% confidence interval [CI], 0.59-0.93), 76% at day 100 (95% CI, 0.55-0.91), and 44% at 1 year (95% CI, 0.24-0.65). At year 1, 13/25 patients were disease progression-free (52%); 11 were responders (1 stringent complete response, 1 complete response, 8 very good partial response, 1 partial response). Three patients remained disease progression-free at 38.6, 59.2, and 60.6 months post-NY-ESO-1 SPEAR T-cell infusion. Median progression-free survival was 13.5 months (range, 3.2-60.6 months); median overall survival was 35.1 months (range, 6.4-66.7 months). Infusions were well tolerated; cytokine release syndrome was not reported. No fatal serious adverse events occurred during study conduct. NY-ESO-1 SPEAR T cells expanded in vivo, trafficked to bone marrow, demonstrated persistence, and exhibited tumor antigen-directed functionality. In this MM patient population, NY-ESO-1 SPEAR T-cell therapy in the context of ASCT was associated with antitumor activity. This trial was registered at www.clinicaltrials.gov as #NCT01352286.

Systemic and local immunity following adoptive transfer of NY-ESO-1 SPEAR T cells in synovial sarcoma.

BACKGROUND: Gene-modified autologous T cells expressing NY-ESO-1c259, an affinity-enhanced T-cell receptor (TCR) reactive against the NY-ESO-1-specific HLA-A*02-restricted peptide SLLMWITQC (NY-ESO-1 SPEAR T-cells; GSK 794), have demonstrated clinical activity in patients with advanced synovial sarcoma (SS). The factors contributing to gene-modified T-cell expansion and the changes within the tumor microenvironment (TME) following T-cell infusion remain unclear. These studies address the immunological mechanisms of response and resistance in patients with SS treated with NY-ESO-1 SPEAR T-cells. METHODS: Four cohorts were included to evaluate antigen expression and preconditioning on efficacy. Clinical responses were assessed by RECIST v1.1. Engineered T-cell persistence was determined by qPCR. Serum cytokines were evaluated by immunoassay. Transcriptomic analyses and immunohistochemistry were performed on tumor biopsies from patients before and after T-cell infusion. Gene-modified T-cells were detected within the TME via an RNAish assay. RESULTS: Responses across cohorts were affected by preconditioning and intra-tumoral NY-ESO-1 expression. Of the 42 patients reported (data cut-off 4June2018), 1 patient had a complete response, 14 patients had partial responses, 24 patients had stable disease, and 3 patients had progressive disease. The magnitude of gene-modified T-cell expansion shortly after infusion was associated with response in patients with high intra-tumoral NY-ESO-1 expression. Patients receiving a fludarabine-containing conditioning regimen experienced increases in serum IL-7 and IL-15. Prior to infusion, the TME exhibited minimal leukocyte infiltration; CD163+ tumor-associated macrophages (TAMs) were the dominant population. Modest increases in intra-tumoral leukocytes (≤5%) were observed in a subset of subjects at approximately 8 weeks. Beyond 8 weeks post infusion, the TME was minimally infiltrated with a TAM-dominant leukocyte infiltrate. Tumor-associated antigens and antigen presentation did not significantly change within the tumor post-T-cell infusion. Finally, NY-ESO-1 SPEAR T cells trafficked to the TME and maintained cytotoxicity in a subset of patients. CONCLUSIONS: Our studies elucidate some factors that underpin response and resistance to NY-ESO-1 SPEAR T-cell therapy. From these data, we conclude that a lymphodepletion regimen containing high doses of fludarabine and cyclophosphamide is necessary for SPEAR T-cell persistence and efficacy. Furthermore, these data demonstrate that non-T-cell inflamed tumors, which are resistant to PD-1/PD-L1 inhibitors, can be treated with adoptive T-cell based immunotherapy. TRIAL REGISTRATION: ClinicalTrials.gov, NCT01343043 , Registered 27 April 2011.

Antitumor Activity Associated with Prolonged Persistence of Adoptively Transferred NY-ESO-1 c259T Cells in Synovial Sarcoma.

We evaluated the safety and activity of autologous T cells expressing NY-ESO-1c259, an affinity-enhanced T-cell receptor (TCR) recognizing an HLA-A2-restricted NY-ESO-1/LAGE1a-derived peptide, in patients with metastatic synovial sarcoma (NY-ESO-1c259T cells). Confirmed antitumor responses occurred in 50% of patients (6/12) and were characterized by tumor shrinkage over several months. Circulating NY-ESO-1c259T cells were present postinfusion in all patients and persisted for at least 6 months in all responders. Most of the infused NY-ESO-1c259T cells exhibited an effector memory phenotype following ex vivo expansion, but the persisting pools comprised largely central memory and stem-cell memory subsets, which remained polyfunctional and showed no evidence of T-cell exhaustion despite persistent tumor burdens. Next-generation sequencing of endogenous TCRs in CD8+ NY-ESO-1c259T cells revealed clonal diversity without contraction over time. These data suggest that regenerative pools of NY-ESO-1c259T cells produced a continuing supply of effector cells to mediate sustained, clinically meaningful antitumor effects.Significance: Metastatic synovial sarcoma is incurable with standard therapy. We employed engineered T cells targeting NY-ESO-1, and the data suggest that robust, self-regenerating pools of CD8+ NY-ESO-1c259T cells produce a continuing supply of effector cells over several months that mediate clinically meaningful antitumor effects despite prolonged exposure to antigen. Cancer Discov; 8(8); 944-57. ©2018 AACR.See related commentary by Keung and Tawbi, p. 914This article is highlighted in the In This Issue feature, p. 899.

NY-ESO-1-specific TCR-engineered T cells mediate sustained antigen-specific antitumor effects in myeloma.

Despite recent therapeutic advances, multiple myeloma (MM) remains largely incurable. Here we report results of a phase I/II trial to evaluate the safety and activity of autologous T cells engineered to express an affinity-enhanced T cell receptor (TCR) recognizing a naturally processed peptide shared by the cancer-testis antigens NY-ESO-1 and LAGE-1. Twenty patients with antigen-positive MM received an average 2.4 × 10(9) engineered T cells 2 d after autologous stem cell transplant. Infusions were well tolerated without clinically apparent cytokine-release syndrome, despite high IL-6 levels. Engineered T cells expanded, persisted, trafficked to marrow and exhibited a cytotoxic phenotype. Persistence of engineered T cells in blood was inversely associated with NY-ESO-1 levels in the marrow. Disease progression was associated with loss of T cell persistence or antigen escape, in accordance with the expected mechanism of action of the transferred T cells. Encouraging clinical responses were observed in 16 of 20 patients (80%) with advanced disease, with a median progression-free survival of 19.1 months. NY-ESO-1-LAGE-1 TCR-engineered T cells were safe, trafficked to marrow and showed extended persistence that correlated with clinical activity against antigen-positive myeloma.

Lymphomyeloid contribution of an immune-restricted progenitor emerging prior to definitive hematopoietic stem cells.

In jawed vertebrates, development of an adaptive immune-system is essential for protection of the born organism against otherwise life-threatening pathogens. Myeloid cells of the innate immune system are formed early in development, whereas lymphopoiesis has been suggested to initiate much later, following emergence of definitive hematopoietic stem cells (HSCs). Herein, we demonstrate that the embryonic lymphoid commitment process initiates earlier than previously appreciated, prior to emergence of definitive HSCs, through establishment of a previously unrecognized entirely immune-restricted and lymphoid-primed progenitor. Notably, this immune-restricted progenitor appears to first emerge in the yolk sac and contributes physiologically to the establishment of lymphoid and some myeloid components of the immune-system, establishing the lymphomyeloid lineage restriction process as an early and physiologically important lineage-commitment step in mammalian hematopoiesis.

beta-Thalassemia: HiJAKing Ineffective Erythropoiesis and Iron Overload.

beta-thalassemia encompasses a group of monogenic diseases that have in common defective synthesis of beta-globin. The defects involved are extremely heterogeneous and give rise to a large phenotypic spectrum, with patients that are almost asymptomatic to cases in which regular blood transfusions are required to sustain life. As a result of the inefficient synthesis of beta-globin, the patients suffer from chronic anemia due to a process called ineffective erythropoiesis (IE). The sequelae of IE lead to extramedullary hematopoiesis (EMH) with massive splenomegaly and dramatic iron overload, which in turn is responsible for many of the secondary pathologies observed in thalassemic patients. The processes are intimately linked such that an ideal therapeutic approach should address all of the complications. Although beta-thalassemia is one of the first monogenic diseases to be described and represents a global health problem, only recently has the scientific community started to focus on the real molecular mechanisms that underlie this disease, opening new and exciting therapeutic perspectives for thalassemic patients worldwide.

Iron metabolism and ineffective erythropoiesis in beta-thalassemia mouse models.

beta-thalassemia is a disease associated with decreased beta-globin production leading to anemia, ineffective erythropoiesis, and iron overload. New mechanisms associated with modulation of erythropoiesis and iron metabolism have recently been discovered in thalassemic mice, improving our understanding of the pathophysiology of this disease. These discoveries have the potential to be translated into clinically-relevant therapeutic options to reduce ineffective erythropoiesis and iron overload. A new generation of therapies based on limiting ineffective erythropoiesis, iron absorption, and the correction of iron maldistribution could be on the way, possibly complementing and improving the current standard of patient care.

Hepcidin as a therapeutic tool to limit iron overload and improve anemia in ß-thalassemic mice.

Excessive iron absorption is one of the main features of ß-thalassemia and can lead to severe morbidity and mortality. Serial analyses of ß-thalassemic mice indicate that while hemoglobin levels decrease over time, the concentration of iron in the liver, spleen, and kidneys markedly increases. Iron overload is associated with low levels of hepcidin, a peptide that regulates iron metabolism by triggering degradation of ferroportin, an iron-transport protein localized on absorptive enterocytes as well as hepatocytes and macrophages. Patients with ß-thalassemia also have low hepcidin levels. These observations led us to hypothesize that more iron is absorbed in ß-thalassemia than is required for erythropoiesis and that increasing the concentration of hepcidin in the body of such patients might be therapeutic, limiting iron overload. Here we demonstrate that a moderate increase in expression of hepcidin in ß-thalassemic mice limits iron overload, decreases formation of insoluble membrane-bound globins and reactive oxygen species, and improves anemia. Mice with increased hepcidin expression also demonstrated an increase in the lifespan of their red cells, reversal of ineffective erythropoiesis and splenomegaly, and an increase in total hemoglobin levels. These data led us to suggest that therapeutics that could increase hepcidin levels or act as hepcidin agonists might help treat the abnormal iron absorption in individuals with ß-thalassemia and related disorders.