Haploinsufficiency for NR3C1, the gene encoding the glucocorticoid receptor, in blastic plasmacytoid dendritic cell neoplasms.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and highly aggressive leukemia for which knowledge on disease mechanisms and effective therapies are currently lacking. Only a handful of recurring genetic mutations have been identified and none is specific to BPDCN. In this study, through molecular cloning in an index case that presented a balanced t(3;5)(q21;q31) and molecular cytogenetic analyses in a further 46 cases, we identify monoallelic deletion of NR3C1 (5q31), encoding the glucocorticoid receptor (GCR), in 13 of 47 (28%) BPDCN patients. Targeted deep sequencing in 36 BPDCN cases, including 10 with NR3C1 deletion, did not reveal NR3C1 point mutations or indels. Haploinsufficiency for NR3C1 defined a subset of BPDCN with lowered GCR expression and extremely poor overall survival (P = .0006). Consistent with a role for GCR in tumor suppression, functional analyses coupled with gene expression profiling identified corticoresistance and loss-of-EZH2 function as major downstream consequences of NR3C1 deletion in BPDCN. Subsequently, more detailed analyses of the t(3;5)(q21;q31) revealed fusion of NR3C1 to a long noncoding RNA (lncRNA) gene (lincRNA-3q) that encodes a novel, nuclear, noncoding RNA involved in the regulation of leukemia stem cell programs and G1/S transition, via E2F. Overexpression of lincRNA-3q was a consistent feature of malignant cells and could be abrogated by bromodomain and extraterminal domain (BET) protein inhibition. Taken together, this work points to NR3C1 as a haploinsufficient tumor suppressor in a subset of BPDCN and identifies BET inhibition, acting at least partially via lncRNA blockade, as a novel treatment option in BPDCN.

Altered functions of plasmacytoid dendritic cells and reduced cytolytic activity of natural killer cells in patients with chronic HBV infection.

BACKGROUND & AIMS: Hepatitis B virus (HBV) modulates the immune system to escape clearance. Plasmacytoid dendritic cells (pDCs) initiate antiviral immunity and might determine outcomes of HBV infections. Functional defects in pDCs and natural killer (NK) cells have been reported in patients with chronic HBV infection. However, the mechanisms of these immune dysfunctions and the interactions between pDCs and NK cells have not been determined. We investigated features of pDCs from patients with chronic HBV infection and their interactions with NK cells. METHODS: We used flow cytometry and cytokine assays to analyze pDCs from patients with chronic HBV infection (118 aviremic and 67 viremic) and compared them with pDCs from uninfected individuals (controls). We performed coculture assays to analyze the ability of pDCs to activate heterologous NK cells. RESULTS: Circulating and hepatic pDCs from patients with chronic HBV infection had higher levels of activation than pDCs from controls and defective responses to stimulation with Toll-like receptor 9 ligand (TLR9-L), regardless of the patient's viral load. TLR9-L-activated pDCs from viremic patients with HBV did not induce cytolytic activity of NK cells. This altered function of pDCs was associated with reduced expression of OX40L and could be reproduced by incubating control pDCs with plasma from viremic patients with HBV. A high level of interferon-induced protein 10 (IP-10 or CXCL10) and hepatitis B surface and e antigens might induce these defective pDC functions. CONCLUSIONS: HBV escapes antiviral immunity by altering pDC functions, to disrupt interactions between pDC and NK cells. This could reduce immune control of HBV and lead to chronic infection.

An innovative plasmacytoid dendritic cell line-based cancer vaccine primes and expands antitumor T-cells in melanoma patients in a first-in-human trial.

The efficacy of immune checkpoint inhibitors has been shown to depend on preexisting antitumor immunity; thus, their combination with cancer vaccines is an attractive therapeutic approach. Plasmacytoid dendritic cells (PDC) are strong inducers of antitumor responses and represent promising vaccine candidates. We developed a cancer vaccine approach based on an allogeneic PDC line that functioned as a very potent antigen-presenting cell in pre-clinical studies. In this phase Ib clinical trial, nine patients with metastatic stage IV melanoma received up to 60 million irradiated PDC line cells loaded with 4 melanoma antigens, injected subcutaneously at weekly intervals. The primary endpoints were safety and tolerability. The vaccine was well tolerated and no serious vaccine-induced side effects were recorded. Strikingly, there was no allogeneic response toward the vaccine, but a significant increase in the frequency of circulating anti-tumor specific T lymphocytes was observed in two patients, accompanied by a switch from a naïve to memory phenotype, thus demonstrating priming of antigen-specific T-cells. Signs of clinical activity were observed, including four stable diseases according to IrRC and vitiligoïd lesions. Four patients were still alive at week 48. We also demonstrate the in vitro enhancement of specific T cell expansion induced by the synergistic combination of peptide-loaded PDC line with anti-PD-1, as compared to peptide-loaded PDC line alone. Taken together, these clinical observations demonstrate the ability of the PDC line based-vaccine to prime and expand antitumor CD8+ responses in cancer patients. Further trials should test the combination of this vaccine with immune checkpoint inhibitors.

Remodeling of B-Cell Subsets in Blood during Pegylated IFNα-2a Therapy in Patients with Chronic Hepatitis B Infection.

The ultimate goal of pegylated interferon-alfa-2a (Peg-IFN-α) therapy in chronic hepatitis B (CHB) infection is HBsAg seroconversion. Even though B cells are major mediators of a positive clinical outcome, their modulation during Peg-IFN-α therapy has not yet been described. We investigated here the effects of Peg-IFN-α on eight circulating B-cell subsets thanks to an original multi-gating approach based on CD19, CD27, IgD, CD10, and CD38 markers in patients with CHB treated with nucleos(t)ide analog alone or in combination with Peg-IFN-α. These dynamic changes were analyzed during the 48-weeks of Peg-IFN-α therapy and up to 2 years after the cessation of treatment. The CD19+CD27-IgD+CD10+CD38high transitional B cells and the CD19+CD27+IgD-CD10-CD38high plasmablasts continuously increased, whereas the CD19+CD27-IgD+CD10-CD38low naive, CD19+CD27+IgD+ natural memory, and CD19+CD27+IgD-CD10-CD38low post-germinal center B cells decreased during the course of Peg-IFNα treatment. Such modulations correlated with a sustained increase in sCD30 levels and the decrease in plasma HBsAg. However, no seroconversion occurred and all parameters returned to baseline after the stop of the treatment. Peg-IFN-α therapy mediates a remodeling of B-cell compartmentalization, without clinical relevance. Our study provides new insights into the immunomodulatory effects of Peg-IFN-α on circulating B-cells, and questioned the benefit of the add-on Peg-IFN-α treatment in CHB.

Pegylated Interferon α-2a Triggers NK-Cell Functionality and Specific T-Cell Responses in Patients with Chronic HBV Infection without HBsAg Seroconversion.

Pegylated interferon α-2a (Peg-IFN-α) represents a therapeutic alternative to the prolonged use of nucleos(t)ide analog (NA) in chronic hepatitis B (CHB) infection. The mechanisms leading to a positive clinical outcome remain unclear. As immune responses are critical for virus control, we investigated the effects of Peg-IFN-α on both innate and adaptive immunity, and related it to the clinical evolution. The phenotypic and functional features of the dendritic cells (DCs), natural killer (NK) cells and HBV-specific CD4/CD8 T cells were analyzed in HBeAg-negative CHB patients treated for 48-weeks with NA alone or together with Peg-IFN-α, before, during and up to 2-years after therapy. Peg-IFN-α induced an early activation of DCs, a potent expansion of the CD56bright NK subset, and enhanced the activation and functionality of the CD56dim NK subset. Peg-IFN-α triggered an increase in the frequencies of Th1- and Th17-oriented HBV-specific CD4/CD8 T cells. Peg-IFN-α reversed the unresponsiveness of patients to a specific stimulation. Most of the parameters returned to baseline after the stop of Peg-IFN-α therapy. Peg-IFN-α impacts both innate and adaptive immunity, overcoming dysfunctional immune responses in CHB patients. These modulations were not associated with seroconversion, which questioned the benefit of the add-on Peg-IFN-α treatment.

Identification of a novel BET bromodomain inhibitor-sensitive, gene regulatory circuit that controls Rituximab response and tumour growth in aggressive lymphoid cancers.

Immuno-chemotherapy elicit high response rates in B-cell non-Hodgkin lymphoma but heterogeneity in response duration is observed, with some patients achieving cure and others showing refractory disease or relapse. Using a transcriptome-powered targeted proteomics screen, we discovered a gene regulatory circuit involving the nuclear factor CYCLON which characterizes aggressive disease and resistance to the anti-CD20 monoclonal antibody, Rituximab, in high-risk B-cell lymphoma. CYCLON knockdown was found to inhibit the aggressivity of MYC-overexpressing tumours in mice and to modulate gene expression programs of biological relevance to lymphoma. Furthermore, CYCLON knockdown increased the sensitivity of human lymphoma B cells to Rituximab in vitro and in vivo. Strikingly, this effect could be mimicked by in vitro treatment of lymphoma B cells with a small molecule inhibitor for BET bromodomain proteins (JQ1). In summary, this work has identified CYCLON as a new MYC cooperating factor that autonomously drives aggressive tumour growth and Rituximab resistance in lymphoma. This resistance mechanism is amenable to next-generation epigenetic therapy by BET bromodomain inhibition, thereby providing a new combination therapy rationale for high-risk lymphoma.