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Different regulatory T cell (Treg) subsets, depending on origin and developmental trajectories, make up the intratumoral Treg pool.Treg identity is the result of integration of several extracellular signals (antigen, costimulatory ligands, cytokines) and the milieu (metabolic substrates) through precise activation of signaling cascades controlling epigenetic regulation of Treg gene transcription.Treg stability may be altered by changes in microenvironmental signals and nutrient abundance.Pharmacological perturbation of T-cell receptor (TCR) signaling, costimulation, and metabolic and epigenetic pathways can be used to reprogram Tregs toward proinflammatory, potentially antitumor T cells.Reprogramming intratumoral Tregs away from their immunosuppressive profiles into interferon γ+(IFN-γ+) T cells can potentiate the antitumor immune response and the activity of immunotherapy.

Missense driver mutations in cancer are concentrated in a few hotspots1. Various mechanisms have been proposed to explain this skew, including biased mutational processes2, phenotypic differences3–6and immunoediting of neoantigens7,8; however, to our knowledge, no existing model weighs the relative contribution of these features to tumour evolution. We propose a unified theoretical ‘free fitness’ framework that parsimoniously integrates multimodal genomic, epigenetic, transcriptomic and proteomic data into a biophysical model of the rate-limiting processes underlying the fitness advantage conferred on cancer cells by driver gene mutations. Focusing on TP53, the most mutated gene in cancer1, we present an inference of mutant p53 concentration and demonstrate that TP53hotspot mutations optimally solve an evolutionary trade-off between oncogenic potential and neoantigen immunogenicity. Our model anticipates patient survival in The Cancer Genome Atlas and patients with lung cancer treated with immunotherapy as well as the age of tumour onset in germline carriers of TP53variants. The predicted differential immunogenicity between hotspot mutations was validated experimentally in patients with cancer and in a unique large dataset of healthy individuals. Our data indicate that immune selective pressure on TP53mutations has a smaller role in non-cancerous lesions than in tumours, suggesting that targeted immunotherapy may offer an early prophylactic opportunity for the former. Determining the relative contribution of immunogenicity and oncogenic function to the selective advantage of hotspot mutations thus has important implications for both precision immunotherapies and our understanding of tumour evolution.

Ten years since the immune checkpoint inhibitor ipilimumab was approved for advanced melanoma, it is time to reflect on the lessons learned regarding modulation of the immune system to treat cancer and on novel approaches to further extend the efficacy of current and emerging immunotherapies. Here, we review the studies that led to our current understanding of the melanoma immune microenvironment in humans and the mechanistic work supporting these observations. We discuss how this information is guiding more precise analyses of the mechanisms of action of immune checkpoint blockade and novel immunotherapeutic approaches. Lastly, we review emerging evidence supporting the negative impact of melanoma metabolic adaptation on anti-tumor immunity and discuss how to counteract such mechanisms for more successful use of immunotherapy.

Limiting metabolic competition in the tumour microenvironment may increase the effectiveness of immunotherapy. Owing to its crucial role in the glucose metabolism of activated T cells, CD28 signalling has been proposed as a metabolic biosensor of T cells1. By contrast, the engagement of CTLA-4 has been shown to downregulate T cell glycolysis1. Here we investigate the effect of CTLA-4 blockade on the metabolic fitness of intra-tumour T cells in relation to the glycolytic capacity of tumour cells. We found that CTLA-4 blockade promotes metabolic fitness and the infiltration of immune cells, especially in glycolysis-low tumours. Accordingly, treatment with anti-CTLA-4 antibodies improved the therapeutic outcomes of mice bearing glycolysis-defective tumours. Notably, tumour-specific CD8+T cell responses correlated with phenotypic and functional destabilization of tumour-infiltrating regulatory T (Treg) cells towards IFNγ- and TNF-producing cells in glycolysis-defective tumours. By mimicking the highly and poorly glycolytic tumour microenvironments in vitro, we show that the effect of CTLA-4 blockade on the destabilization of Tregcells is dependent on Tregcell glycolysis and CD28 signalling. These findings indicate that decreasing tumour competition for glucose may facilitate the therapeutic activity of CTLA-4 blockade, thus supporting its combination with inhibitors of tumour glycolysis. Moreover, these results reveal a mechanism by which anti-CTLA-4 treatment interferes with Tregcell function in the presence of glucose.

Depleting regulatory T cells (Tregcells) to counteract immunosuppressive features of the tumor microenvironment (TME) is an attractive strategy for cancer treatment; however, autoimmunity due to systemic impairment of their suppressive function limits its therapeutic potential. Elucidating approaches that specifically disrupt intratumoral Tregcells is direly needed for cancer immunotherapy. We found that CD36 was selectively upregulated in intrautumoral Tregcells as a central metabolic modulator. CD36 fine-tuned mitochondrial fitness via peroxisome proliferator-activated receptor-β signaling, programming Tregcells to adapt to a lactic acid-enriched TME. Genetic ablation of Cd36in Tregcells suppressed tumor growth accompanied by a decrease in intratumoral Tregcells and enhancement of antitumor activity in tumor-infiltrating lymphocytes without disrupting immune homeostasis. Furthermore, CD36 targeting elicited additive antitumor responses with anti-programmed cell death protein 1 therapy. Our findings uncover the unexplored metabolic adaptation that orchestrates the survival and functions of intratumoral Tregcells, and the therapeutic potential of targeting this pathway for reprogramming the TME.

Modulating T cell homeostatic mechanisms with checkpoint blockade can efficiently promote endogenous anti-tumor T cell responses1–11. However, many patients still do not benefit from checkpoint blockade12, highlighting the need for targeting of alternative immune pathways13. Glucocorticoid-induced tumor necrosis factor receptor-related protein (GITR) is an attractive target for immunotherapy, owing to its capacity to promote effector T cell (Teff) functions14,15and hamper regulatory T cell (Treg) suppression16–20. On the basis of the potent preclinical anti-tumor activity of agonist anti-GITR antibodies, reported by us and others16,21,22, we initiated the first in-human phase 1 trial of GITR agonism with the anti-GITR antibody TRX518 (NCT01239134). Here, we report the safety profile and immune effects of TRX518 monotherapy in patients with advanced cancer and provide mechanistic preclinical evidence to rationally combine GITR agonism with checkpoint blockade in future clinical trials. We demonstrate that TRX518 reduces circulating and intratumoral Tregcells to similar extents, providing an easily assessable biomarker of anti-GITR activity. Despite Tregreductions and increased Teff:Tregratios, substantial clinical responses were not seen. Similarly, in mice with advanced tumors, GITR agonism was not sufficient to activate cytolytic T cells due to persistent exhaustion. We demonstrate that T cell reinvigoration with PD-1 blockade can overcome resistance of advanced tumors to anti-GITR monotherapy. These findings led us to start investigating TRX518 with PD-1 pathway blockade in patients with advanced refractory tumors (NCT02628574). GITR agonism can be exploited in combination with checkpoint blockade to overcome immune refractoriness in solid tumors.

ABSTRACTFocal radiation therapy (RT) has attracted considerable attention as a combinatorial partner for immunotherapy (IT), largely reflecting a well-defined, predictable safety profile and at least some potential for immunostimulation. However, only a few RT-IT combinations have been tested successfully in patients with cancer, highlighting the urgent need for an improved understanding of the interaction between RT and IT in both preclinical and clinical scenarios. Every year since 2016, ImmunoRad gathers experts working at the interface between RT and IT to provide a forum for education and discussion, with the ultimate goal of fostering progress in the field at both preclinical and clinical levels. Here, we summarize the key concepts and findings presented at the Sixth Annual ImmunoRad conference.

The analysis of T-cell antigens in long-term survivors of pancreatic ductal adenocarcinoma suggests that neoantigen immunogenicity and quality, not purely quantity, correlate with survival.

We have shown that human B-cell non-Hodgkin lymphomas (B-NHLs) express heat shock protein (HSP)H1/105 in function of their aggressiveness. Here, we now clarify its role as a functional B-NHL target by testing the hypothesis that it promotes the stabilization of key lymphoma oncoproteins. HSPH1 silencing in 4 models of aggressive B-NHLs was paralleled by Bcl-6 and c-Myc downregulation. In vitro and in vivo analysis of HSPH1-silenced Namalwa cells showed that this effect was associated with a significant growth delay and the loss of tumorigenicity when 104cells were injected into mice. Interestingly, we found that HSPH1 physically interacts with c-Myc and Bcl-6 in both Namalwa cells and primary aggressive B-NHLs. Accordingly, expression of HSPH1 and either c-Myc or Bcl-6 positively correlated in these diseases. Our study indicates that HSPH1 concurrently favors the expression of 2 key lymphoma oncoproteins, thus confirming its candidacy as a valuable therapeutic target of aggressive B-NHLs.

The majority of JAK2V617F-negative myeloproliferative neoplasms (MPNs) have disease-initiating frameshift mutations in calreticulin (CALR), resulting in a common carboxyl-terminal mutant fragment (CALRMUT), representing an attractive source of neoantigens for cancer vaccines. However, studies have shown that CALRMUT-specific T cells are rare in patients with CALRMUTMPN for unknown reasons. We examined class I major histocompatibility complex (MHC-I) allele frequencies in patients with CALRMUTMPN from two independent cohorts. We observed that MHC-I alleles that present CALRMUTneoepitopes with high affinity are underrepresented in patients with CALRMUTMPN. We speculated that this was due to an increased chance of immune-mediated tumor rejection by individuals expressing one of these MHC-I alleles such that the disease never clinically manifested. As a consequence of this MHC-I allele restriction, we reasoned that patients with CALRMUTMPN would not efficiently respond to a CALRMUTfragment cancer vaccine but would when immunized with a modified CALRMUTheteroclitic peptide vaccine approach. We found that heteroclitic CALRMUTpeptides specifically designed for the MHC-I alleles of patients with CALRMUTMPN efficiently elicited a CALRMUTcross-reactive CD8+T cell response in human peripheral blood samples but not to the matched weakly immunogenic CALRMUTnative peptides. We corroborated this effect in vivo in mice and observed that C57BL/6J mice can mount a CD8+T cell response to the CALRMUTfragment upon immunization with a CALRMUTheteroclitic, but not native, peptide. Together, our data emphasize the therapeutic potential of heteroclitic peptide–based cancer vaccines in patients with CALRMUTMPN.

Transcription factors ThPOK and Runx3 regulate the differentiation of “helper” CD4+ and “cytotoxic” CD8+ T cell lineages respectively, inducing single positive (SP) T cells that enter the periphery with the expression of either the CD4 or CD8 co-receptor. Despite the expectation that these cell fates are mutually exclusive and that mature CD4+CD8+ double positive (DP) T cells are present in healthy individuals and augmented in the context of disease, yet their molecular features and pathophysiologic role are disputed. Here, we show DP T cells in murine and human tumors as a heterogenous population originating from SP T cells which re-express the opposite co-receptor and acquire features of the opposite cell type’s phenotype and function following TCR stimulation. We identified distinct clonally expanded DP T cells in human melanoma and lung cancer by scRNA sequencing and demonstrated their tumor reactivity in cytotoxicity assays. Our findings indicate that antigen stimulation induces SP T cells to differentiate into DP T cell subsets gaining in polyfunctional characteristics.

Microbial diversity is associated with improved outcomes in recipients of allogeneic hematopoietic cell transplantation (allo-HCT), but the mechanism underlying this observation is unclear. In a cohort of 174 patients who underwent allo-HCT, we demonstrate that a diverse intestinal microbiome early after allo-HCT is associated with an increased number of innate-like mucosal-associated invariant T (MAIT) cells, which are in turn associated with improved overall survival and less acute graft-versus-host disease (aGVHD). Immune profiling of conventional and unconventional immune cell subsets revealed that the prevalence of Vδ2 cells, the major circulating subpopulation of γδ T cells, closely correlated with the frequency of MAIT cells and was associated with less aGVHD. Analysis of these populations using both single-cell transcriptomics and flow cytometry suggested a shift toward activated phenotypes and a gain of cytotoxic and effector functions after transplantation. A diverse intestinal microbiome with the capacity to produce activating ligands for MAIT and Vδ2 cells appeared to be necessary for the maintenance of these populations after allo-HCT. These data suggest an immunological link between intestinal microbial diversity, microbe-derived ligands, and maintenance of unconventional T cells.

We reported that the clinical efficacy of dendritic cell–based vaccination is strongly associated with immunologic responses in relapsed B-cell non-Hodgkin lymphoma (B-NHL) patients. We have now investigated whether postvaccination antibodies from responders recognize novel shared NHL-restricted antigens. Immunohistochemistry and flow cytometry showed that they cross-react with allogeneic B-NHLs at significantly higher levels than their matched prevaccination samples or nonresponders' antibodies. Western blot analysis of DOHH-2 lymphoma proteome revealed a sharp band migrating at approximately 100 to 110 kDa only with postvaccine repertoires from responders. Mass spectrometry identified heat shock protein-105 (HSP105) in that molecular weight interval. Flow cytometry and immunohistochemistry disclosed HSP105 on the cell membrane and in the cytoplasm of B-NHL cell lines and 97 diagnostic specimens. A direct correlation between HSP105 expression and lymphoma aggressiveness was also apparent. Treatment of aggressive human B-NHL cell lines with an anti-HSP105 antibody had no direct effects on cell cycle or apoptosis but significantly reduced the tumor burden in xenotransplanted immunodeficient mice. In vivo antilymphoma activity of HSP105 engagement was associated with a significant local increase of Granzyme B+ killer cells that very likely contributed to the tumor-restricted necrosis. Our study adds HSP105 to the list of nononcogenes that can be exploited as antilymphoma targets.

Eighteen relapsed patients with measurable indolent non-Hodgkin lymphoma (NHL) were vaccinated with dendritic cells (DCs) loaded with killed autologous tumor cells. Six patients had objective clinical responses including 3 continuous complete responses (CRs) and 3 partial responses (PRs), with a median follow up of 50.5 months. Eight patients had stable disease, whereas 4 had progressive disease. Clinical responses were significantly associated with a reduction in CD4+CD25+FOXP3+ regulatory T cells, an increase in CD3−CD56dimCD16+ natural killer (NK) cells, and maturation of lymphocytes to the effector memory stage in either postvaccination peripheral blood or tumor specimen samples. In partial responding patients, vaccination significantly boosted the IFN-γ–producing T-cell response to autologous tumor challenge. In one HLA-A*0201+ patient who achieved CR, IL-4 release by circulating T cells in response to tumor-specific IgH-encoded peptides was also documented. Immunohistochemical analysis of tumor biopsies using biotin-conjugated autologous serum samples revealed a tumor-restricted humoral response only in the postvaccination serum from responding patients. Collectively these results demonstrate that vaccination with tumor-loaded DCs may induce both T- and B-cell responses and produces clinical benefits in indolent NHL patients with measurable disease. This study is registered with the Istituto Superiore di Sanità: http://www.iss.it with protocol number 7578-PRE 21-801.

Eighteen relapsed patients with measurable indolent non-Hodgkin lymphoma (NHL) were vaccinated with dendritic cells (DCs) loaded with killed autologous tumor cells. Six patients had objective clinical responses including 3 continuous complete responses (CRs) and 3 partial responses (PRs), with a median follow up of 50.5 months. Eight patients had stable disease, whereas 4 had progressive disease. Clinical responses were significantly associated with a reduction in CD4+CD25+FOXP3+regulatory T cells, an increase in CD3−CD56dimCD16+natural killer (NK) cells, and maturation of lymphocytes to the effector memory stage in either postvaccination peripheral blood or tumor specimen samples. In partial responding patients, vaccination significantly boosted the IFN-γ–producing T-cell response to autologous tumor challenge. In one HLA-A*0201+patient who achieved CR, IL-4 release by circulating T cells in response to tumor-specific IgH-encoded peptides was also documented. Immunohistochemical analysis of tumor biopsies using biotin-conjugated autologous serum samples revealed a tumor-restricted humoral response only in the postvaccination serum from responding patients. Collectively these results demonstrate that vaccination with tumor-loaded DCs may induce both T- and B-cell responses and produces clinical benefits in indolent NHL patients with measurable disease. This study is registered with the Istituto Superiore di Sanità: http://www.iss.itwith protocol number 7578-PRE 21-801.

Microbial diversity is associated with improved outcome in patients receiving allogeneic hematopoietic cell transplantation (allo-HCT), however, the mechanism underlying this observation is unclear. Unconventional T cells recognize specific metabolites of bacterial biosynthesis and their role in the post-HCT immunity has not yet been fully clarified. Here we have performed an observational study (n = 174 patients) using 16S rRNA sequencing of early post-HCT patient stool samples (day 7-21 after HCT) paired with multiparameter flow cytometry (performed at day 30 and day 100 after HCT) to explore the relationship between the intestinal microbiome early after HCT and the unconventional T cell populations in circulation. Our data extend findings of other groups suggesting that mucosal-associated invariant T (MAIT) cells are dependent on a diverse microbiome and are also associated with favorable allo-HCT outcome. In addition, we report for the first time that the Vδ2 subset of γδ T cells is positively correlated with MAIT cells as well as independent predictors of favorable transplant outcome.

Gomes: Xbiome: Current Employment. Zappasodi: iTeos Therapeutics: Consultancy; Astra Zeneca: Research Funding; Bristol Myers Squibb: Research Funding. Ponce: CareDx: Consultancy, Honoraria; Takeda Pharmaceuticals: Research Funding; Generon Pharmaceuticals: Consultancy; Kadmon pharmaceuticals: Consultancy, Honoraria; Ceramedix: Consultancy, Honoraria; Seres Therapeutics: Consultancy, Research Funding. Giralt: JENSENN: Membership on an entity's Board of Directors or advisory committees; SANOFI: Membership on an entity's Board of Directors or advisory committees; AMGEN: Membership on an entity's Board of Directors or advisory committees; PFIZER: Membership on an entity's Board of Directors or advisory committees; GSK: Membership on an entity's Board of Directors or advisory committees; JAZZ: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; CELGENE: Membership on an entity's Board of Directors or advisory committees; Actinnum: Membership on an entity's Board of Directors or advisory committees. Peled: Seres: Other: Intellectual Property Rights, Research Funding and Travelfees; DaVolterra: Consultancy; Other: Other: Jonathan U. Peled had filed intellectual property applications related to the microbiome (referencenumbers #62/843,849, #62/977,908, and #15/756,845); MaaT Pharma: Consultancy. Perales: Cidara: Honoraria; Celgene: Honoraria; Merck: Honoraria; MorphoSys: Honoraria; Nektar Therapeutics: Honoraria, Other; Equilium: Honoraria; Karyopharm: Honoraria; Takeda: Honoraria; Bristol-Myers Squibb: Honoraria; Kite/Gilead: Honoraria, Other; Medigene: Honoraria; Novartis: Honoraria, Other; Sellas Life Sciences: Honoraria; Servier: Honoraria; Miltenyi Biotec: Honoraria, Other; Omeros: Honoraria; Incyte: Honoraria, Other; NexImmune: Honoraria. van den Brink: Rheos: Honoraria; Merck & Co, Inc: Honoraria; Therakos: Honoraria; Amgen: Honoraria; GlaskoSmithKline: Other: has consulted, received honorarium from or participated in advisory boards; Synthekine (Spouse): Other: has consulted, received honorarium from or participated in advisory boards; Kite Pharmaceuticals: Other; Notch Therapeutics: Honoraria; Nektar Therapeutics: Honoraria; Priothera: Research Funding; Wolters Kluwer: Patents & Royalties; Juno Therapeutics: Other; Frazier Healthcare Partners: Honoraria; DKMS (nonprofit): Other; Seres: Other: Honorarium, Intellectual Property Rights, Research Fundingand Stock Options; Forty-Seven, Inc.: Honoraria; Lygenesis: Other: has consulted, received honorarium from or participated in advisory boards ; WindMILTherapeutics: Honoraria; Pharmacyclics: Other; Jazz Pharmaceuticals: Honoraria; Novartis (Spouse): Other: has consulted, received honorarium from or participated in advisory boards; Da Volterra: Other: has consulted, received honorarium from or participated in advisory boards; Ceramedix: Other: has consulted, received honorarium from or participated in advisory boards ; MagentaTherapeutics: Honoraria; Pluto Therapeutics: Current holder of stock options in a privately-held company, Other: has consulted, received honorarium from or participated in advisory boards .

Phosphatidylserine (PS) is exposed on the surface of apoptotic cells and is known to promote immunosuppressive signals in the tumor microenvironment (TME). Antibodies that block PS interaction with its receptors have been shown to repolarize the TME into a proinflammatory state. Radiation therapy (RT) is an effective focal treatment of isolated solid tumors but is less effective at controlling metastatic cancers. We found that tumor-directed RT caused an increase in expression of PS on the surface of viable immune infiltrates in mouse B16 melanoma. We hypothesize that PS expression on immune cells may provide negative feedback to immune cells in the TME. Treatment with an antibody that targets PS (mch1N11) enhanced the anti-tumor efficacy of tumor-directed RT and improved overall survival. This combination led to an increase in proinflammatory tumor-associated macrophages. The addition of anti-PD-1 to RT and mch1N11 led to even greater anti-tumor efficacy and overall survival. We found increased PS expression on several immune subsets in the blood of patients with metastatic melanoma after receiving tumor-directed RT. These findings highlight the potential of combining PS targeting with RT and PD-1 pathway blockade to improve outcomes in patients with advanced-stage cancers.

Gianni: Hoffmann-La Roche: Consultancy, Honoraria.

Abstract 1562

No relevant conflicts of interest to declare.

Abstract 2729

No relevant conflicts of interest to declare.

Abstract 463

Background and Objectives: The significant toxicities associated with current treatments of Burkitt’s lymphoma (BL) have fostered the identification of novel targets for effective but less toxic therapies. c-myc overexpression is the hallmark of BL; however it is per se insufficient to cause lymphoma development. Recent studies indicating aberrant expression of microRNAs (miRNAs) in BL have raised the possibility of a c-myc - miRNA interaction within the genesis and the maintenance of the lymphoma phenotype. Myc oncoproteins indeed have been found to inhibit the transcription of tumor suppressor genes. This occurs for instance by recruiting histone deacetylase (HDAC) 1 proteins to target genes, including tissue transglutaminase 2 (TG2), a multifunctional protein that promotes apoptosis and differentiation in normal tissues. Since inhibitors of the epigenetic regulator HDACs are revealing very effective as anticancer agents, we evaluated ITF2357, a new hydroxamate inhibitor of HDAC, with respect to its ability to induce proliferative arrest and apoptosis in BL cell lines by modulating c-myc mRNA, miRNAs and TG2 expression. Methods and Results: Cell growth inhibition by ITF2357 was determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay in the BL cell lines Namalwa and Raji. ITF2357 IC50 was 200nM after 48h exposure. Most treated Namalwa and Raji cells became respectively late and early apoptotic as assessed by annexin V and propidium iodide staining. Accordingly, ITF235 induced SUBG1 peak formation in Namalwa cells and G1 arrest in Raji cells. Repeated addition of ITF2357 at 24h-intervals enhanced these effects. Array analyses and quantitative real-time PCR of miRNAs indicated a significant decrease in the expression of miR-155 and miR-98, which exert oncogenic activity in MYC-associated tumors, at 24–72 h after treatment. Conversely, the Let-7a miRNA, which targets the c-MYC mRNA stabilizer IMP-1 among its tumor suppressive functions, was up regulated peaking at 24h after drug administration. Finally, immunohistochemical analysis of TG2 expression in ITF2357-treated Raji cells revealed a diffuse cytoplasmic staining, whereas in their untreated counterparts TG2 was sporadically and faintly detectable. Despite ITF2357 restored the expression of different targets of myc, quantitative real-time PCR revealed no parallel decrease in c-myc mRNA suggesting that the epigenetic modulation provided by ITF2357 on BL cell lines did not directly affect myc expression level. Conclusion: Our data indicate potent cytotoxic and growth inhibitory activities of ITF2357 on BL cell lines. These effects might be related to the modulation of both oncogenic and tumor-suppressing miRNAs and to the restoration of the tumor suppressor TG2. Further evidences for the potential candidacy of ITF2357 as a therapeutic agent for BL awaits ongoing analyses in BL primary tumors and in animal models.

Background and Objectives: The significant toxicities associated with current treatments of Burkitt's lymphoma (BL) have fostered the identification of novel targets for effective but less toxic therapies. c-myc overexpression is the hallmark of BL; however it is per se insufficient to cause lymphoma development. Recent studies indicating aberrant expression of microRNAs (miRNAs) in BL have raised the possibility of a c-myc - miRNA interaction within the genesis and the maintenance of the lymphoma phenotype. Myc oncoproteins indeed have been found to inhibit the transcription of tumor suppressor genes. This occurs for instance by recruiting histone deacetylase (HDAC) 1 proteins to target genes, including tissue transglutaminase 2 (TG2), a multifunctional protein that promotes apoptosis and differentiation in normal tissues. Since inhibitors of the epigenetic regulator HDACs are revealing very effective as anticancer agents, we evaluated ITF2357, a new hydroxamate inhibitor of HDAC, with respect to its ability to induce proliferative arrest and apoptosis in BL cell lines by modulating c-myc mRNA, miRNAs and TG2 expression.