Clinical implications of phosphorylated STAT3 expression in De Novo diffuse large B-cell lymphoma

Cytokine profiles in patients with newly diagnosed diffuse large B-cell lymphoma: IL-6 and IL-10 levels are associated with adverse clinical features and poor outcomes

BACKGROUND

The development of diffuse large B-cell lymphoma (DLBCL), a prevalent subgroup of non-Hodgkin lymphoma (NHL), potentially involves various cytokines. We aimed to determine the correlation between deregulated serum levels of cytokines and clinical features and investigate their impact on the prognosis of patients with DLBCL.

METHODS

We conducted a retrospective study of 77 patients with newly diagnosed DLBCL to explore the relationships between different cytokines, adverse clinical features, and poor outcomes. The Mann-Whitney U test was used to compare the cytokine profiles between patients with DLBCL and healthy controls. The Kaplan-Meier method was used to analyze the probability of survival, and the log-rank tests were used to evaluate the differences between survival curves. The Cox proportional hazards regression model was used to performed univariate and multivariate analyses to evaluate prognostic variables for survival analyze.

RESULTS

Serum levels of interleukin-2 (IL-2), tumor necrosis factor (TNF)-α, IL-6, IL-10, and IFN-γ were significantly elevated in patients with untreated DLBCL. Serum levels of IL-6 and IL-10 were significantly higher in patients with an International Prognostic Index (IPI) of 3-5, bone marrow involvement, serum levels of LDH ≥ 250 U/L, and β2-microglobulin (β2-MG) levels ≥ 2.3 mg/L. Patients with B symptoms only had higher serum IL-10 levels, whereas patients with a partial response or no response to treatment had significantly elevated serum levels of IL-6 as well as IL-10. Significant positive correlations were observed between the levels of IL-6 and IL-10 with those of β2-MG and LDH. Patients with levels of IL-6 ≥ 4.5 or IL-10 ≥ 5.0 pg/mL, as well as combined elevated IL-6 and IL-10 levels, exhibited shorter progression-free survival and overall survival. Additionally, univariate and multivariate analyses revealed that serum levels of IL-6 ≥ 4.5 pg/mL and IL-10 ≥ 5.0 pg/mL and IPI 3-5 were independent prognostic factors for relapse and survival in patients with DLBCL.

CONCLUSIONS

Pre-treatment serum IL-6 and IL-10 levels in patients with newly diagnosed DLBCL might be powerful markers for determining treatment response and predicting the prognosis of DLBCL.

Evaluation of Signal Transducer and Activator of Transcription 3 (STAT-3) Protein Expression in Non-Hodgkin Lymphoma Cases in Hospital USM

BACKGROUND

Evolving targeted therapy on Janus Associated Kinase-Signal Transducer and Activator of Transcription (JAK-STAT) signaling pathway, especially pertaining to STAT-3 protein in non-Hodgkin lymphoma (NHL), provides new treatment strategies. STAT-3 protein also relates to the prognostication of NHL. Hence, we aimed to evaluate the expression of STAT-3 protein in NHL cases diagnosed in Hospital Universiti Sains Malaysia (USM).

METHODS

A retrospective cross sectional study using formalin fixed paraffin embedded (FFPE) tissue blocks of 95 NHL cases were obtained. STAT-3 immunostaining was performed and evaluated. The proportion and association between the expression of STAT-3 protein with subtypes of NHL were statistically analyzed.

RESULTS

The majority of the cases (78.9%) had positive STAT-3 protein expression. 64.2% were among aggressive B cell NHL, whilst 20.0% of them were diffuse large B cell lymphoma, a non-germinal center B subtype (DLBCL-NGCB). There is also an association between STAT-3 protein expression with DLBCL subtypes (p = 0.046).

CONCLUSION

Our study demonstrated a remarkable expression of STAT-3 protein in NHL, in which DLBCL subtypes had significant association. A larger scale study with a combination of JAK protein evaluation should be undertaken in the future.

Low-frequency ultrasound irradiation increases paclitaxel-induced sarcoma cells apoptosis and facilitates the transmembrane delivery of drugs

Sarcoma is a malignant tumor derived from interstitial tissues and requires comprehensive treatment including chemotherapy. Paclitaxel (PTX) is an active agent against sarcoma, but its effect is not sufficiently acceptable and needs to be improved. Low-frequency ultrasound (LFU) has been documented to improve the efficacy of drugs by inducing reversible changes in membrane permeability; however, the effects of the combined use of LFU and PTX for sarcoma tumors remain unclear and warrant further investigation. We investigated the effects of 30 kHz LFU treatment combined with PTX on sarcoma cells A-204 and HT-1080 by analyzing in vitro apoptosis and cell growth inhibition rates, and determined their antitumor effects by examining tumor weights with or without LFU in the S180 sarcoma xenograft model. Drug concentrations in the subcutaneous tumors were measured using high performance liquid chromatography (HPLC). LFU combined with PTX significantly induced cell apoptosis, and blocked the cell cycle of sarcoma cells in G2/M phase, and furthermore, inhibited the activation of JAK2/STAT3 signaling pathway. Meanwhile, LFU combined with PTX inhibited the expression of PD-L1 in vitro, suggesting the potential of enhanced antitumor immunity by this treatment. LFU combined with PTX significantly inhibited the growth of S180 tumors transplanted subcutaneously in Institute of Cancer Research (ICR) mice, and its enhanced effect may be associated with increased local concentrations of PTX in tumor tissues in vivo, with no significant adverse subsequences on body weight observed. We conclude that the combination of LFU and PTX has synergistic antitumor effects and is a candidate for subcutaneous treatment of sarcoma by further increasing the intracellular concentration of PTX.

Establishment and characterization of a new activated B-cell-like DLBCL cell line, TMD12

We report the establishment of a novel activated B-cell-like (ABC) diffuse large B-cell lymphoma (DLBCL) cell line, designated as TMD12, from a patient with highly refractory DLBCL. ABC-DLBCL is a subtype with a relatively unfavorable prognosis that was originally categorized using gene expression profiling according to its cell of origin. TMD12 cells were isolated from the pleural effusion of the patient at relapse and passaged continuously in vitro for >4 years. The cells displayed cluster of differentiation (CD)19, CD20, CD22, CD38, human leukocyte antigen-DR isotype, and κ positivity and CD5, CD10, CD23, and λ negativity, as detected using flow cytometric analysis. The chromosomal karyotypic analysis, including the spectral karyotyping method, confirmed t(1;19)(q21:q13.1), del(6q23), gain of chromosome 18, and other abnormalities. Mutation analyses, including whole-exome sequencing, revealed that TMD12 cells harbored mutations in MYD88 and CD79B, indicating an ABC subtype. TMD12 cells exhibited chronic active B-cell receptor signaling and constitutive activation of the nuclear factor κB pathway, which is typically associated with sensitivity to a specific Bruton tyrosine kinase inhibitor, ibrutinib. Intriguingly, TMD12 cells displayed moderate resistance to ibrutinib and lacked activation of Janus kinase/signal transducers and activators of transcription 3 signaling, another hallmark of this DLBCL subtype. Treatment with an inhibitor against tumor progression locus 2 (TPL2), a multifunctional intracellular kinase that is activated particularly downstream of Toll-like receptors or MYD88 and IκB kinase α/β (IKKα/β), suppressed the proliferation of TMD12 cells, implying the possible involvement of the TPL2-p105 pathway in the tumorigenesis of ABC-DLBCL. Because only a limited number of ABC-DLBCL cell lines are currently available, TMD12 cells might provide a useful tool in the search for novel druggable targets for this intractable lymphoma.

PD-1/PD-L1 Pathway: A Therapeutic Target in CD30+ Large Cell Lymphomas

The programmed death-ligands, PD-L1 and PD-L2, reside on tumor cells and can bind with programmed death-1 protein (PD-1) on T-cells, resulting in tumor immune escape. PD-1 ligands are highly expressed in some CD30+ large cell lymphomas, including classic Hodgkin lymphoma (CHL), primary mediastinal large B-cell lymphoma (PMBL), Epstein–Barr virus (EBV)-positive diffuse large B-cell lymphoma (EBV+ DLBCL), and anaplastic large cell lymphoma (ALCL). The genetic alteration of the chromosome 9p24.1 locus, the location of PD-L1, PD-L2, and JAK2 are the main mechanisms leading to PD-L1 and PD-L2 overexpression and are frequently observed in these CD30+ large cell lymphomas. The JAK/STAT pathway is also commonly constitutively activated in these lymphomas, further contributing to the upregulated expression of PD-L1 and PD-L2. Other mechanisms underlying the overexpression of PD-L1 and PD-L2 in some cases include EBV infection and the activation of the mitogen-activated protein kinase (MAPK) pathway. These cellular and molecular mechanisms provide a scientific rationale for PD-1/PD-L1 blockade in treating patients with relapsed/refractory (R/R) disease and, possibly, in newly diagnosed patients. Given the high efficacy of PD-1 inhibitors in patients with R/R CHL and PMBL, these agents have become a standard treatment in these patient subgroups. Preliminary studies of PD-1 inhibitors in patients with R/R EBV+ DLBCL and R/R ALCL have also shown promising results. Future directions for these patients will likely include PD-1/PD-L1 blockade in combination with other therapeutic agents, such as brentuximab or traditional chemotherapy regimens.

The Effect of the Tumor Microenvironment on Lymphoid Neoplasms Derived from B Cells

Lymphomas are characteristic tumors surrounded by an inflammatory microenvironment. The cells of the microenvironment are essential for the growth and survival of neoplastic cells and are recruited through the effect of cytokines/chemokines. Lymphomas include heterogeneous groups of neoplasms infiltrating various lymphoid structures which may arise from B lymphocytes, T lymphocytes, and natural killer (NK) cells at various stages of their differentiation state. In this review article, we analyze the literature data concerning the involvement of the tumor microenvironment (TME) in the progression of lymphomas and the recent advances in the analysis of microenvironment components in the most common forms: some mature B cell lymphoma neoplasms and classic Hodgkin lymphomas. The complex crosstalk between the TME and tumor cells led to the discovery of many mechanisms usable as molecular-targeted therapy through the control of diverse elements of the TME, varying from inhibitors of angiogenic cytokines and their receptors to the regulation of cells' activities and the novel immune checkpoint inhibitors.

Tumor cell-derived IL-10 promotes cell-autonomous growth and immune escape in diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) is an aggressive malignancy arising from germinal center or post-germinal center B-cells that retain many of the properties of normal B-cells. Here we show that a subset of DLBCL express the cytokine IL-10 and its receptor. The genetic ablation of IL-10 receptor signaling abrogates the autocrine STAT3 phosphorylation triggered by tumor cell-intrinsic IL-10 expression and impairs growth of DLBCL cell lines in subcutaneous and orthotopic xenotransplantation models. Furthermore, we demonstrate using an immunocompetent Myc-driven model of DLBCL that neutralization of IL-10 signaling reduces tumor growth, which can be attributed to reduced Treg infiltration, stronger intratumoral effector T-cell responses, and restored tumor-specific MHCII expression. The effects of IL-10R neutralization were phenocopied by the genetic ablation of IL-10 signaling in the Treg compartment and could be reversed by MHCII blockade. The BTK inhibitor ibrutinib effectively blocked tumor cell-intrinsic IL-10 expression and tumor growth in this Myc-driven model. Tumors from patients with high IL-10RA expression are infiltrated by higher numbers of Tregs than IL-10RA^low patients. Finally, we show in 16 cases of DLBCL derived from transplant patients on immunosuppressive therapy that IL-10RA expression is less common in this cohort, and Treg infiltration is not observed.

TLR9 expression in chronic lymphocytic leukemia identifies a promigratory subpopulation and novel therapeutic target

Chronic lymphocytic leukemia (CLL) remains incurable despite B-cell receptor-targeted inhibitors revolutionizing treatment. This suggests that other signaling molecules are involved in disease escape mechanisms and resistance. Toll-like receptor 9 (TLR9) is a promising candidate that is activated by unmethylated cytosine guanine dinucleotide-DNA. Here, we show that plasma from patients with CLL contains significantly more unmethylated DNA than plasma from healthy control subjects (P < .0001) and that cell-free DNA levels correlate with the prognostic markers CD38, β2-microglobulin, and lymphocyte doubling time. Furthermore, elevated cell-free DNA was associated with shorter time to first treatment (hazard ratio, 4.0; P = .003). We also show that TLR9 expression was associated with in vitro CLL cell migration (P < .001), and intracellular endosomal TLR9 strongly correlated with aberrant surface expression (sTLR9; r = 0.9). In addition, lymph node-derived CLL cells exhibited increased sTLR9 (P = .016), and RNA-sequencing of paired sTLR9hi and sTLR9lo CLL cells revealed differential transcription of genes involved in TLR signaling, adhesion, motility, and inflammation in sTLR9hi cells. Mechanistically, a TLR9 agonist, ODN2006, promoted CLL cell migration (P < .001) that was mediated by p65 NF-κB and STAT3 transcription factor activation. Importantly, autologous plasma induced the same effects, which were reversed by a TLR9 antagonist. Furthermore, high TLR9 expression promoted engraftment and rapid disease progression in a NOD/Shi-scid/IL-2Rγnull mouse xenograft model. Finally, we showed that dual targeting of TLR9 and Bruton's tyrosine kinase (BTK) was strongly synergistic (median combination index, 0.2 at half maximal effective dose), which highlights the distinct role for TLR9 signaling in CLL and the potential for combined targeting of TLR9 and BTK as a more effective treatment strategy in this incurable disease.

The Positivity of Phosphorylated STAT3 Is a Novel Marker for Favorable Prognosis in Germinal Center B-Cell Type of Diffuse Large B-Cell Lymphoma

On the basis of immunohistochemistry, diffuse large B-cell lymphoma (DLBCL) is categorized as a germinal center B-cell (GCB) or non-GCB subtype. Recent integrated genomic analyses have highlighted the importance of the JAK-STAT3 pathway in the molecular pathogenesis of DLBCL. However, its relevance to clinical outcomes remains controversial. Therefore, we evaluated the extent of the nuclear expression of phosphorylated STAT3 (pSTAT3), a surrogate marker of signal transducer and activator of transcription 3 (STAT3) activation, by immunohistochemistry. We also analyzed the potential relationship between pSTAT3 positivity (defined as ≥40% positive neoplastic cells) and clinicopathologic characteristics in 294 patients with DLBCL. pSTAT3 was detected in 122 patients (42%), with a higher rate in the non-GCB subtype than in the GCB subtype (57% vs. 28%, P<0.001). Factors potentially activating STAT3, MYD88L265P, and Epstein-Barr virus-encoded small RNA were identified in the pSTAT3-positive non-GCB subtype, whereas the pSTAT3-positive GCB subtype often showed STAT3 mutations and lacked EZH2 mutations and the rearrangements of BCL2 and MYC. Multivariate analyses revealed that the pSTAT3-positive GCB subtype showed a favorable prognosis (HR: 0.17; 95% confidence interval, 0.04-0.7; P=0.014). These findings suggest that pSTAT3 positivity may have a unique impact on the clinicopathologic characteristics of DLBCL, making it a promising novel marker for the favorable prognosis of patients with the GCB subtype.

Targeting STAT3 with Proteolysis Targeting Chimeras and Next-Generation Antisense Oligonucleotides

STAT3 has been recognized for its key role in the progression of cancer, where it is frequently upregulated or constitutively hyperactivated, contributing to tumor cell proliferation, survival, and migration, as well as angiogenesis and suppression of antitumor immunity. Given the ubiquity of dysregulated STAT3 activity in cancer, it has long been considered a highly attractive target for the development of anticancer therapies. Efforts to target STAT3, however, have proven to be especially challenging, perhaps owing to the fact that transcription factors lack targetable enzymatic activity and have historically been considered "undruggable." Small-molecule inhibitors targeting STAT3 have been limited by insufficient selectivity and potency. More recently, therapeutic approaches that selectively target STAT3 protein for degradation have been developed, offering novel strategies that do not rely on inhibition of upstream pathways or direct competitive inhibition of the STAT3 protein. Here, we review these emerging approaches, including the development of STAT3 proteolysis targeting chimera agents, as well as preclinical and clinical studies of chemically stabilized antisense molecules, such as the clinical agent AZD9150. These therapeutic strategies may robustly reduce the cellular activity of oncogenic STAT3 and overcome the historical limitations of less selective small molecules.

A Phase 1b Study to Evaluate the Safety and Efficacy of Durvalumab in Combination With Tremelimumab or Danvatirsen in Patients With Relapsed or Refractory Diffuse Large B-Cell Lymphoma

BACKGROUND

Despite recent advances, outcomes in patients with relapsed/refractory diffuse large B-cell lymphoma (DLBCL) remain poor. Immune checkpoint inhibitors have shown limited efficacy in this setting, but combinations with novel agents may enhance benefit. Combination therapy with durvalumab, an anti-programmed death ligand 1 (PD-L1) antibody, and danvatirsen (AZD9150; an antisense oligonucleotide inhibiting signal transducer and activator of transcription 3 [STAT3]) or tremelimumab (an anti-cytotoxic T-lymphocyte-associated antigen 4 [CTLA-4] antibody) may augment endogenous antitumor activity.

PATIENTS AND METHODS

In this phase 1b dose escalation and dose expansion study, we evaluated durvalumab 20 mg/kg every 4 weeks plus either tremelimumab 1 mg/kg every 4 weeks or danvatirsen 2 or 3 mg/kg (administered on days 1, 3, 5, 8, 15, and 22, then every week). Treatment continued until disease progression. The primary endpoint was safety; secondary endpoints included efficacy, pharmacokinetics, and immunogenicity.

RESULTS

As of April 4, 2019, 32 patients were enrolled and treated, receiving a median of 2 prior lines of systemic therapy. Treatment-related adverse events occurred in 21 patients (65.6%), most commonly alanine aminotransferase/aspartate aminotransferase increased (grade 1-3), anemia (grade 1-3), and fatigue (grade 1). The overall objective response rate was 6.3%, with 2 partial responses. Median time to response was 11.0 weeks (range, 7.7-14.3 weeks). Median progression-free survival was 7.4 weeks (range, 0.1-31.4 weeks), and median overall survival was 28.0 weeks (range, 1.9-115.4 weeks).

CONCLUSION

The primary endpoint was met, with durvalumab plus tremelimumab/danvatirsen generally well tolerated in patients with relapsed/refractory DLBCL; however, antitumor activity was limited.

Overexpression of OCT-1 gene is a biomarker of adverse prognosis for diffuse large B-cell lymphoma (DLBCL): data from a retrospective cohort of 77 Brazilian patients

BACKGROUND

OCT-1 gene is a member of the POU-homeodomain family of transcriptional regulators of B-lymphocyte differentiation by controlling expression of B-cell specific genes. BCL-2 gene is a potent inhibitor of apoptosis and it is essential during B-cell differentiation into germinal center. These genes may be expressed in diffuse large B-cell lymphoma (DLBCL), but the role of BCL-2 in its prognosis has been contradictory, and OCT-1 has yet to be tested.

METHODS

In this study, we aimed to investigate the prognostic impact of OCT-1 and BCL-2 expression in DLBCL treated in the real world with immunochemotherapy in a single center. BCL-2 and OCT-1 genes were available in 78.5% (77/98) DLBCL patients, and the RNA for quantitative real-time PCR was isolated from formalin-fixed paraffin-embedded samples. The values obtained for gene expression were transformed in categorical variable according to their median.

RESULTS

Cohort median age was 54.5 years (15-84), 49 (50%) were male, 38/77 (49.4%) and 40/77 (51.9%) presented OCT-1 and BCL-2 expression ≥ median, respectively. The overall response rate (ORR) in all patients was 68.4% (67/98), 65,3% (64/98) of patients acquired complete response, and 3.1% (3/98) partial response, while 6.1% (6/98) were primary refractory. The median follow-up was 3.77 years (95% CI: 3.2-4.1), with 5.43 (95% CI: 2.2-NR) of overall survival (OS) and 5.15 years (95% CI: 2.9-NA) of progression free survival (PFS). OCT-1 ≥ median was associated with shorter OS at univariate analysis (p = 0.013; [HR] 2.450, 95% CI: 1.21-4.96) and PFS (p = 0.019; [HR] 2.270, 95%CI: 1.14-4.51) and BCL-2 gene overexpression presented worse PFS (p = 0.043, [HR] 2.008, 95% CI: 1.02-3.95). At multivariate analysis, OCT-1 overexpression was associated with poor PFS (p = 0.035, [HR] 2.22, 95% CI: 1.06-4.67).

CONCLUSION

In this study, we showed that overexpression of OCT1 gene was an independent prognostic factor of adverse outcomes in DLBCL.

Clinicopathologic significance of MYD88 L265P mutation and expression of TLR4 and P-STAT3 in primary central nervous system diffuse large B-cell lymphomas

Patients with primary central nervous system lymphoma (PCNSL) have a prognosis poorer than that of systemic lymphoma patients. In patients with this condition, TLR4/STAT3 pathway alterations and the MYD88 L265P mutation may be viable targets for therapeutic intervention. The present study was, therefore, designed to identify clinicopathologic correlates of MYD88 mutations and TLR4/STAT3 pathway alterations in PCNSL. We detected TLR4 and p-STAT3 in 41.5% (22/53) and 43.4% (23/53) of PCNSL patients, respectively, while 60.4% of these patients (32/53) were found to harbor the MYD88 L265P mutation. TLR4 expression was found to be significantly associated with the presence of multiple brain lesions, while p-STAT3 expression was significantly linked to advanced age, the presence of multiple brain lesions, non-GCB histological findings, and non-CR status. The presence of the MYD88 L265P mutation was significantly linked to advanced age, the presence of multiple brain lesions, and DLBCL molecular subtype. Multivariate analyses additionally confirmed that elevated TLR4 and p-STAT3 expression levels are associated with a poorer PCNSL patient prognosis. Based on these findings, we hypothesize that signaling through the TLR4/MYD88/STAT3 pathway plays a key role in the pathogenesis of PCNSL.

Plasma soluble PD-L1 and STAT3 predict the prognosis in diffuse large B cell lymphoma patients

Purpose: Diffuse large B cell lymphoma (DLBCL) is one of the most common B cell lymphomas, which displays heterogeneous pathologies. Programmed cell death 1/ programmed cell death ligand 1 (PD-1/PD-L1) plays an essential role in immunosuppression in multiple malignancies. Signal transducer and activator of transcription 3 (STAT3)-positive patients also have an independently inferior clinical outcome. However, there are no reports on the effect of plasma soluble PD-L1 (sPD-L1) combined with plasma STAT3 on the prognosis of DLBCL. In this study, we investigate the relationships between plasma sPD-L1 combined with STAT3 and clinical prognosis of DLBCL.

Methods: Levels of plasma sPD-L1 and STAT3 were quantified using ELISA in eighty-seven DLBCL patients. Multiplexed immunofluorescence staining was performed to visualize the expression of PD-L1 in twenty-nine matched FFPE specimens from all patients.

Results: The survival analysis revealed that the progression-free survival (PFS) and overall survival (OS) in high sPD-L1 level group were poorer than that in low sPD-L1 level group (PFS, P < 0.001; OS, P < 0.001). Similarly, the PFS and OS in high STAT3 level group were also poorer than that in low STAT3 level group. Multivariate cox regression analysis showed that both high sPD-L1 and high STAT3 levels were the independent prognostic factors negatively affecting survival. In addition, patients with DLBCL having high levels of both sPD-L1 and STAT3 had a worse outcome than those patients having any one high or low levels of both (P < 0.001).

Conclusions: We therefore revealed that high levels of plasma sPD-L1 and STAT3 are associated with inferior outcome for DLBCL patients, suggesting that combined measurement of their levels in plasma may be a promising prognostic strategy for DLBCL patients.

New Insights into Diffuse Large B-Cell Lymphoma Pathobiology

Diffuse large B-cell lymphoma (DLBCL) is the most common non-Hodgkin lymphoma (NHL), accounting for about 40% of all cases of NHL. Analysis of the tumor microenvironment is an important aspect of the assessment of the progression of DLBCL. In this review article, we analyzed the role of different cellular components of the tumor microenvironment, including mast cells, macrophages, and lymphocytes, in the tumor progression of DLBCL. We examined several approaches to confront the available pieces of evidence, whereby three key points emerged. DLBCL is a disease of malignant B cells spreading and accumulating both at nodal and at extranodal sites. In patients with both nodal and extranodal lesions, the subsequent induction of a cancer-friendly environment appears pivotal. The DLBCL cell interaction with mature stromal cells and vessels confers tumor protection and inhibition of immune response while delivering nutrients and oxygen supply. Single cells may also reside and survive in protected niches in the nodal and extranodal sites as a source for residual disease and relapse. This review aims to molecularly and functionally recapitulate the DLBCL–milieu crosstalk, to relate niche and pathological angiogenic constitution and interaction factors to DLBCL progression.

STAT3-driven hematopoiesis and lymphopoiesis abnormalities are dependent on serine phosphorylation

Deregulated activation of the latent transcription factor STAT3 has been implicated in the pathogenesis of myeloproliferative and lymphoproliferative hematologic disorders. The uncontrolled activation of STAT3 has traditionally been assigned to its elevated phosphorylation at tyrosine 705 (pY705) and associated nuclear transcriptional activity. By contrast, a transcriptional role for serine 727 phosphorylation (pS727) of STAT3 has recently emerged, suggesting that pS727 may account for the pathological activity of STAT3 in certain disease settings. Here, by coupling pS727-STAT3-deficient Stat3SA/SA mice with a STAT3-driven mouse model (gp130F/F) for myeloproliferative and lymphoproliferative pathologies, we reveal a key role for pS727-STAT3 in promoting multiple hematologic pathologies. The genetic blockade of pS727-STAT3 in gp130F/F:Stat3SA/SA mice ameliorated the neutrophilia, thrombocytosis, splenomegaly and lymphadenopathy that are features of gp130F/F mice. The protection against thrombocytosis in gp130F/F:Stat3SA/SA mice coincided with normalized megakaryopoiesis in both bone marrow and spleen compartments. Interestingly, pS727-STAT3-mediated abnormal lymphopoiesis in gp130F/F mice was more pronounced in lymph nodes compared to thymus, and was characterized by elevated numbers of B cells at the expense of T cells. Furthermore, pS727-STAT3 dependency for these hematologic pathologies coincided with transcriptional activity on STAT3-regulated genes, rather than its effect on mitochondrial and metabolic genes. Collectively, these findings suggest that pS727 plays a critical pathological role in modulating the transcriptional activity of STAT3 in hematologic disorders.

Signal Pathways and Therapeutic Prospects of Diffuse Large B Cell Lymphoma

BACKGROUND

Diffuse Large B Cell Lymphoma (DLBCL) is the most common type of non-Hodgkin lymphoma which is heterogeneous both clinically and morphologically. Over the past decades, significant advances have been made in the understanding of the molecular genesis, leading to the identification of multiple pathways and molecules that can be targeted for clinical benefit.

OBJECTIVE

The current review aims to present a brief overview of signal pathways of DLBCL, which mainly focus on B-cell antigen Receptor (BCR), Nuclear Factor-κB (NF-κB), Phosphatidylinositol-3-Kinase (PI3K) - protein kinase B (Akt) - mammalian Target of Rapamycin (mTOR), Janus Kinase (JAK) - Signal Transducer and Activator (STAT), Wnt/β-catenin, and P53 pathways.

METHODS

Activation of signal pathways may contribute to the generation, development, chemotherapy sensitivity of DLBCL, and expression of pathway molecules is associated with the prognosis of DLBCL. Some agents targeting these pathways have been proved effective and relevant clinical trials are in progress. These agents used single or combined with chemotherapy/each other might raise the possibility of improving clinical outcomes in DLBCL.

CONCLUSION

This review presents several signal pathways of DLBCL and targeted agents had a tendency to improve the curative effect, especially in high-risk or relapsed/refractory DLBCL.

STAT3 Activation and Oncogenesis in Lymphoma

Signal transducer and activator of transcription 3 (STAT3) is an important and the most studied transcription factor in the Janus kinase (JAK)/STAT signaling pathway. STAT3 mediates the expression of various genes that play a critical role in many cellular and biological processes, such as cell proliferation, survival, differentiation, migration, angiogenesis, and inflammation. STAT3 and associated JAKs are activated and tightly regulated by a variety of cytokines and growth factors and their receptors in normal immune responses. However, abnormal expression of STAT3 leads to its constitutive activation, which promotes malignant transformation and tumor progression through oncogenic gene expression in numerous human cancers. Human lymphoma is a heterogeneous malignancy of T and B lymphocytes. Constitutive signaling by STAT3 is an oncogenic driver in several types of B-cell lymphoma and most of T-cell lymphomas. Aberrant STAT3 activation can also induce inappropriate expression of genes involved in tumor immune evasion such as PD-L1. In this review, we focus on the oncogenic role of STAT3 in human lymphoma and highlight potential therapeutic intervention by targeting JAK/STAT3 signaling.

Emerging role of histone deacetylase inhibitors in the treatment of diffuse large B-cell lymphoma

Although current immunochemotherapy has increased the therapeutic efficacy in diffuse large B-cell lymphoma (DLBCL), there are still some patients who present unfavorable outcomes. Novel effective treatment strategies are needed to improve the prognosis of DLBCL. In this review, we discussed the functional mechanisms and therapeutic applications of histone deacetylases inhibitors (HDIs) in DLBCL from preclinical and clinical studies. The mechanistic rationale of HDIs involved a wide range of effects including the regulation of transcription factors, tumor suppressors, and cell surface molecules. Histone deacetylases inhibitors as monotherapy performed limited activity in the treatment of DLBCL in present clinical trials, but its combination with other regimens has emerged as potential treatment candidates with generally acceptable and manageable adverse effects. Further investigation on the anti-tumor mechanisms of HDIs and ongoing clinical trials will hopefully facilitate the application of HDIs in patients with DLBCL.

STAT3 Activation Is Associated with Interleukin-10 Expression and Survival in Primary Central Nervous System Lymphoma

BACKGROUND

The findings from several studies have confirmed that signal transducer and activator of transcription 3 (STAT3) is constitutively phosphorylated in primary central nervous system lymphoma (PCNSL). However, the underlying mechanism and prognostic significance of STAT3 activation have not yet been clarified.

METHODS

The expression of STAT3, phosphorylated STAT3 (p-STAT3), and interleukin (IL)-10 was examined in 32 PCNSL samples using immunohistochemistry. The relationship between IL-10 expression and STAT3 phosphorylation was determined. In addition, the associations of the expression of these proteins with the clinical factors and survival were analyzed.

RESULTS

Expression of STAT3, p-STAT3, and IL-10 was detected in 28 (87.5%), 17 (53.1%), and 25 (78.1%) samples, respectively. IL-10 expression was significantly associated with STAT3 phosphorylation in PCNSL (P = 0.033). STAT3 phosphorylation and IL-10 expression were associated with the presence of multiple brain lesions (P = 0.004 and P = 0.027, respectively), suggesting that STAT3 activation might enhance the intracranial spread of tumors in PCNSL. The 2-year overall survival and progression-free survival (PFS) rates were 67.8% and 35.5%, respectively. Kaplan-Meier survival analysis demonstrated that STAT3 phosphorylation, IL-10 expression, and multiple brain lesions were significantly associated with PFS in those with PCNSL (P = 0.009, P = 0.030, and P = 0.040, respectively). However, Cox regression analysis indicated that only STAT3 phosphorylation was significantly associated with shorter PFS (hazard ratio, 3.22; 95% confidence interval, 1.24-8.37; P = 0.016).

CONCLUSION

Our results have indicated that STAT3 activation is closely related to IL-10 expression and that p-STAT3 might be a novel biomarker predictive of poor survival in those with PCNSL.

The IL-6 signaling complex is a critical driver, negative prognostic factor, and therapeutic target in diffuse large B-cell lymphoma

Interleukin-6 (IL-6) is a growth factor for normal B cells and plasma cell-derived malignancies. Here, we show that the IL-6 signaling pathway is also active in a subset of diffuse large B-cell lymphoma (DLBCL) patients with particularly poor prognosis. Primary DLBCL cells and DLBCL cell lines expressing IL-6R engraft and form orthotopic lymphomas in humanized mice that ectopically produce human IL-6, and in mice reconstituted with a human immune system. We show that a subset of DLBCL cases have evolved mechanisms that ensure constitutive activation of the IL-6 signaling pathway, i.e., the expression of both chains of the IL-6R, the expression of the cytokine itself, and the mutational inactivation of a negative regulator of IL-6 signaling, SOCS1. IL-6 signaling promotes MYC-driven lymphomagenesis in a genetically engineered model, and treatment with the IL-6R-specific antibody tocilizumab reduces growth of primary DLBCL cells and of DLBCL cell lines in various therapeutic settings. The combined results uncover the IL-6 signaling pathway as a driver and negative prognosticator in aggressive DLBCL that can be targeted with a safe and well-tolerated biologic.

Evaluation of S1PR1, pSTAT3, S1PR2, FOXP1 Expression in Aggressive, Mature B Cell Lymphomas

Background

Aggressive, mature B-cell lymphomas include Burkitt Lymphoma (BL), High Grade B Cell Lymphomas (HGBL) (eg, Double-Hit B cell lymphomas (HGBL-DH: HGBL with MYC and BCL2 and/or BCL6 translocations)), HGBL, Not Otherwise Specified (HGBL, NOS) and Diffuse Large B Cell Lymphoma (DLBCL). Overlapping morphologic and immunohistochemical features of these lymphomas pose diagnostic challenges in some cases, and better understanding of potential diagnostic biomarkers and possible therapeutic targets is needed. Sphingosine 1 Phosphate Receptors (S1PR1-5) are G-protein coupled receptors that bind S1P and influence migration and survival in multiple cell types, including lymphocytes. S1PRs are emerging as biomarkers in B cell biology and interaction between S1PR pathways and STAT3 or FOXP1 has been reported in DLBCL.

Aim and Methods

Our aim was to extend the understanding of S1PR1, STAT3 and S1PR2, FOXP1 expression beyond DLBCL, into additional aggressive, mature B cell lymphomas using immunohistochemical expression analysis of human tissue samples.

Results

S1PR1 and S1PR2 showed different expression patterns in mantle zones and follicle centers in reactive lymphoid tissue. BL showed a unique expression pattern compared to HGBL and DLBCL. Additionally, S1PR1 and S1PR2 expression were typically mutually exclusive and were expressed in a low proportion of cases (frequently HGBL involving extranodal sites). FOXP1 was expressed in a high proportion of various case types and pSTAT3 was detected in a significant proportion of HGBL and DLBCL.

Conclusions

These findings provide further evidence that S1PR1, pSTAT3, S1PR2 and FOXP1 play a role in a subset of aggressive, mature B cell lymphomas.

Prognostic values and clinical implications of programmed cell death-ligand 1 (PD-L1), fork head transcription factor P-1 (FOXP-1) and signal transducer and activator of transcription-3 (STAT-3) expression in diffuse large B-cell lymphoma (DLBCL); an immunohistochemical study

Context

PD-L1 is an inhibitory ligand that functions as an essential immune checkpoint. FOXP-1 is a member of the FOXP family. STAT-3 plays a critical role in regulation of cell proliferation and survival. The detailed expression of the three markers together in DLBCL tissues and their prognostic value in patients with DLBCL were not fully investigated.

Aim was to assess the expression of PD-L1, FOXP-1 and STAT-3 in diffuse large B-cell lymphoma (DLBCL) and to correlate their expression with the pathological findings, prognostic parameters and clinical implications of patients.

Methods

PD-L1, FOXP-1 and STAT-3 were assessed in DLBCL tissues derived from 50 patients using immunohistochemistry. Patients were followed up for 3 years for response to therapy progression, recurrence and survival.

Results

High PD-L1 expression was associated with bone marrow involvement (p = 0.004), extra-nodal involvement (p = 0.006) and advanced stage (p = 0.003). High FOXP-1 expression was associated with presence of bone marrow involvement and high risk group (p < 0.001). High STAT-3 expression was associated with older age of the patient (p < 0.001), presence of bone marrow involvement (p = 0.002), extra-nodal involvement (p = 0.009), and high risk group (p = 0.005). High expression of PD-L1, FOXP-1 and STAT-3 was related to poor response to therapy, poor OS rate and RFS rates (p < 0.001).

Conclusion

High expression of PD-L1, FOXP-1 and STAT-3 was related poor prognosis in DLBCL patients.

STAT-3 RNAscope Determination in Human Diffuse Large B-Cell Lymphoma

BACKGROUND: Diffuse large B-cell lymphoma (DLBCL) is the most common form of non-Hodgkin's lymphoma. Signal transducer and activator of transcription 3 (STAT3) is a cytoplasmic transcription with many important functions, including regulation of cell proliferation, differentiation, survival, angiogenesis, and immune response. MATERIALS AND METHODS: In this study, we have compared by means of RNAscope technology STAT3 RNA expression in human DLBCL in a selected group of activated B-cell–like DLBCL (ABC-DLBCL) patients with another group of germinal center B-cell–like DLBCL (GBC-DLBCL) patients. RESULTS: The results have shown that ABC DLBCL tissue samples contained a significantly higher number of STAT3-positive cells as compared with GCB tissue samples. Moreover, by means of confocal immunofluorescence analysis, we have observed that tumor vessels in ABC samples appeared lined by endothelial cells expressing both FVIII and STAT3 signals, while in GCB samples, only few vessels coexpressed FVIII and STAT3. CONCLUSIONS: These data confirm other reports showing that STAT3 is highly expressed and activated in ABC-DLBCL and our previously published data demonstrating that, in primary central nervous system lymphoma, tumor vessels appeared lined by endothelial cells expressing both FVIII and STAT3.

Clinicopathologic implication of PD-L1 and phosphorylated STAT3 expression in diffuse large B cell lymphoma

BACKGROUND

Antitumor immune response of programmed cell death ligand (PD-L1) has shown clinical value not only in Hodgkin lymphoma and EBV-associated lymphomas but also in EBV-negative diffuse large B cell lymphoma (DLBCL) of non-germinal center B cell-like (non-GCB) subtype. Signal transducer and activator of transcription 3 (STAT3) is known to induce PD-L1 in immune cells and its activated form, phosphorylated STAT3 (pSTAT3), is also frequently expressed in non-GCB DLBCL. Herein, we investigated associations between PD-L1 expression/gene alteration, pSTAT3 expression and clinicopathologic variables in EBV-negative DLBCL.

METHODS

In 107 cases of DLBCLs with non-GCB subtype (67%; 72/107), GCB subtype (25%; 27/107) and unclassifiable cases (8%; 8/107), we performed PD-L1 and pSTAT3 immunohistochemistry and fluorescence in situ hybridization for PD-L1 gene translocation and copy number gain/amplification.

RESULTS

PD-L1 was expressed in tumor cells (PD-L1t) in 21% (23/107; 30% cutoff), immune cells (PD-L1i) in 36% (38/107; 20% cutoff), and pSTAT3 in tumor nuclei in 41% (44/107; 40% cutoff). PD-L1 gene alteration was observed in 10% (10/102) including translocation in 6% (6/102) and copy number gain/amplification in 4% (4/102). Non-GCB subtype was associated with PD-L1t and pSTAT3 (p = 0.006 and p = 0.042), and tended to have PD-L1 gene alteration (p = 0.058). Tumoral PD-L1 expression without gene alteration (PD-L1t+ GA-) correlated with pSTAT3-positive tumor cell proportions (%) (p = 0.033). In survival analysis, pSTAT3 expression independently predicted shorter PFS in total cohort (p = 0.017) and R-CHOP-treated group (p = 0.007), and in pSTAT3-negative R-CHOP-treated subset, PD-L1 expression in immune cells (PD-L1i) correlated with shorter PFS (p = 0.042).

CONCLUSIONS

Gene alteration and protein expression of PD-L1 and pSTAT3 expression were closely related in DLBCL and constituted features of non-GCB subtype. In addition to known clinical significance of pSTAT3, immune cell expression of PD-L1 (PD-L1i) had also clinical value in pSTAT3-dependent manner. These findings may provide an insight into immunotherapeutic strategy and risk stratification in DLBCL patients.

STAT3 antisense oligonucleotide AZD9150 in a subset of patients with heavily pretreated lymphoma: results of a phase 1b trial

Background

The Janus kinase (JAK) and signal transduction and activation of transcription (STAT) signaling pathway is an attractive target in multiple cancers. Activation of the JAK-STAT pathway is important in both tumorigenesis and activation of immune responses. In diffuse large B-cell lymphoma (DLBCL), the transcription factor STAT3 has been associated with aggressive disease phenotype and worse overall survival. While multiple therapies inhibit upstream signaling, there has been limited success in selectively targeting STAT3 in patients. Antisense oligonucleotides (ASOs) represent a compelling therapeutic approach to target difficult to drug proteins such as STAT3 through of mRNA targeting. We report the evaluation of a next generation STAT3 ASO (AZD9150) in a non-Hodgkin’s lymphoma population, primarily consisting of patients with DLBCL.

Methods

Patients with relapsed or treatment refractory lymphoma were enrolled in this expansion cohort. AZD9150 was administered at 2 mg/kg and the 3 mg/kg (MTD determined by escalation cohort) dose levels with initial loading doses in the first week on days 1, 3, and 5 followed by weekly dosing. Patients were eligible to remain on therapy until unacceptable toxicity or progression. Blood was collected pre- and post-treatment for analysis of peripheral immune cells.

Results

Thirty patients were enrolled, 10 at 2 mg/kg and 20 at 3 mg/kg dose levels. Twenty-seven patients had DLBCL. AZD9150 was safe and well tolerated at both doses. Common drug-related adverse events included transaminitis, fatigue, and thrombocytopenia. The 3 mg/kg dose level is the recommended phase 2 dose. All responses were seen among DLBCL patients, including 2 complete responses with median duration of response 10.7 months and 2 partial responses. Peripheral blood cell analysis of three patients without a clinical response to therapy revealed a relative increase in proportion of macrophages, CD4+, and CD8+ T cells; this trend did not reach statistical significance.

Conclusions

AZD9150 was well tolerated and demonstrated efficacy in a subset of heavily pretreated patients with DLBCL. Studies in combination with checkpoint immunotherapies are ongoing.

Trial registration

Registered at ClinicalTrials.gov: NCT01563302. First submitted 2/13/2012.

Electronic supplementary material

The online version of this article (10.1186/s40425-018-0436-5) contains supplementary material, which is available to authorized users.

Loss of TNFAIP3 enhances MYD88L265P-driven signaling in non-Hodgkin lymphoma

MYD88 mutations are one of the most recurrent mutations in hematologic malignancies. However, recent mouse models suggest that MYD88L265P alone may not be sufficient to induce tumor formation. Interplay between MYD88L265P and other genetic events is further supported by the fact that TNFAIP3 (A20) inactivation often accompanies MYD88L265P. However, we are still lacking information about the consequence of MYD88L265P in combination with TNFAIP3 loss in human B cell lymphoma. Review of our genetic data on diffuse large B cell lymphoma (DLBCL) and Waldenstrom macroglobulinemia (WM), found that a large percentage of DLBCL and WM cases that have a MYD88 mutation also harbor a TNFAIP3 loss, 55% DLBCL and 28% of WM, respectively. To mimic this combination of genetic events, we used genomic editing technology to knock out TNFAIP3 in MYD88L265P non-Hodgkin's lymphoma (NHL) cell lines. Loss of A20 expression resulted in increased NF-κB and p38 activity leading to upregulation of the NF-κB target genes BCL2 and MYC. Furthermore, we detected the increased production of IL-6 and CXCL10 which led to an upregulation of the JAK/STAT pathway. Overall, these results suggest that MYD88L265P signaling can be enhanced by a second genetic alteration in TNFAIP3 and highlights a potential opportunity for therapeutic targeting.

B-cell receptor-mediated NFATc1 activation induces IL-10/STAT3/PD-L1 signaling in diffuse large B-cell lymphoma

Knowledge of programmed death ligand 1 (PD-L1) expression and its regulation in B-cell lymphoma cells is limited. Investigating mechanisms that control PD-L1 expression in B-cell lymphoma cells might identify biomarkers that predict the efficacy of immunotherapy with anti-programmed death-1/PD-L1 antibodies. In addition, identification of mechanisms that regulate PD-L1 may identify molecules that can be targeted to improve the clinical efficacy of immune checkpoint inhibitors. In this study, we used proteomic approaches and patient-derived B-cell lymphoma cell lines to investigate mechanisms that regulate PD-L1 expression. We found that PD-L1 expression, particularly in nongerminal center B cell-derived diffuse large B-cell lymphoma (DLBCL), is controlled and regulated by several interactive signaling pathways, including the B-cell receptor (BCR) and JAK2/STAT3 signaling pathways. We found that that BCR-mediated NFATc1 activation upregulates IL-10 chemokine expression in PD-L1⁺ B-cell lymphoma cells. Released IL-10 activates the JAK2/STAT3 pathway, leading to STAT3-induced PD-L1 expression. IL-10 antagonist antibody abrogates IL-10/STAT3 signaling and PD-L1 protein expression. We also found that BCR pathway inhibition by BTK inhibitors (ibrutinib, acalabrutinib, and BGB-3111) blocks NFATc1 and STAT3 activation, thereby inhibiting IL-10 and PD-L1 expression. Finally, we validated the PD-L1 signaling network in 2 primary DLBCL cohorts consisting of 428 and 350 cases and showed significant correlations among IL-10, STAT3, and PD-L1. Thus, our findings reveal a complex signaling network regulating PD-L1 expression in B-cell lymphoma cells and suggest that PD-L1 expression can be modulated by small molecule inhibitors to potentiate immunotherapies.

Highly Tumorigenic Diffuse Large B Cell Lymphoma Cells Are Produced by Coculture with Stromal Cells

BACKGROUND/AIMS

Diffuse large B cell lymphoma (DLBCL) is heterogeneous. We aimed to explore how tumor microenvironment promotes lymphoma cell aggressiveness and heterogeneity.

METHODS

We created a coculture system using human DLBCL cells and mouse bone marrow stromal cells. Proliferative capacity, drug resistance, clonogenicity, and tumorigenicity were compared in lymphoma cells from the coculture system and lymphoma cells cultured alone. Expression of Notch signaling associated genes was evaluated using real-time reverse transcriptase PCR and Western blot.

RESULTS

Lymphoma cells in the coculture system differentiated into a suspended cell group and an adherent cell group. They acquired a stronger proliferative capacity and drug resistance than lymphoma cells cultured alone, and differences existed between the adherent cell and suspended cell groups. The suspended cell group acquired the most powerful clonogenic and tumorigenic potential. However, Notch3 was exclusively expressed in the adherent lymphoma cell group and the use of N-[N-(3, 5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester, an inhibitor of Notch pathway, could abolish the emergence of highly aggressive lymphoma cells.

CONCLUSION

Highly tumorigenic lymphoma cells could be generated by coculture with stromal cells, and it was dependent on Notch3 expression in the adjacent lymphoma cells through interaction with stromal cells.

Clinical Significance of PTEN Deletion, Mutation, and Loss of PTEN Expression in De Novo Diffuse Large B-Cell Lymphoma

PTEN loss has been associated with poorer prognosis in many solid tumors. However, such investigation in lymphomas is limited. In this study, PTEN cytoplasmic and nuclear expression, PTEN gene deletion, and PTEN mutations were evaluated in two independent cohorts of diffuse large B-cell lymphoma (DLBCL). Cytoplasmic PTEN expression was found in approximately 67% of total 747 DLBCL cases, more frequently in the activated B-cell–like subtype. Nuclear PTEN expression was less frequent and at lower levels, which significantly correlated with higher PTEN mRNA expression. Remarkably, loss of PTEN protein expression was associated with poorer survival only in DLBCL with AKT hyperactivation. In contrast, high PTEN expression was associated with Myc expression and poorer survival in cases without abnormal AKT activation. Genetic and epigenetic mechanisms for loss of PTEN expression were investigated. PTEN deletions (mostly heterozygous) were detected in 11.3% of DLBCL, and showed opposite prognostic effects in patients with AKT hyperactivation and in MYC rearranged DLBCL patients. PTEN mutations, detected in 10.6% of patients, were associated with upregulation of genes involved in central nervous system function, metabolism, and AKT/mTOR signaling regulation. Loss of PTEN cytoplasmic expression was also associated with TP53 mutations, higher PTEN-targeting microRNA expression, and lower PD-L1 expression. Remarkably, low PTEN mRNA expression was associated with down-regulation of a group of genes involved in immune responses and B-cell development/differentiation, and poorer survival in DLBCL independent of AKT activation. Collectively, multi-levels of PTEN abnormalities and dysregulation may play important roles in PTEN expression and loss, and that loss of PTEN tumor-suppressor function contributes to the poor survival of DLBCL patients with AKT hyperactivation.

Mutations in the signal transducer and activator of transcription family of genes in cancer

In recent years, it has become clear that members of the signal transducer and activator of transcription (STAT) family of genes play an important role in cancer. The STAT family consists of seven genes, STAT1‐4,STAT5A, STAT5B and STAT6, that are involved in regulating cellular proliferation, apoptosis, angiogenesis and the immune system response. Constitutive activation of STAT3, via mutational changes, is important in oncogenesis in both solid and hematopoietic cancers. In the case of hematopoietic neoplasms, STAT3 driver mutations have been described in T‐cell large granular lymphocytic (T‐LGL) leukemia and chronic natural killer lymphoproliferative disorders (CLPD‐NK) and are seen in 30%‐40% of T‐LGL leukemia patients. STAT5B is also mutated in T‐LGL leukemia and CLPD‐NK, but in a much smaller proportion. Here we review past and current research on STAT genes in hematopoietic and solid cancers with emphasis on STAT3 and STAT5B and their roles in the pathogenesis of hematopoietic malignancies, particularly T‐LGL leukemia and CLPD‐NK.

B Cell Lymphoma Immunotherapy Using TLR9-Targeted Oligonucleotide STAT3 Inhibitors

Growing evidence links the aggressiveness of non-Hodgkin’s lymphoma, especially the activated B cell-like type diffuse large B cell lymphomas (ABC-DLBCLs) to Toll-like receptor 9 (TLR9)/MyD88 and STAT3 transcription factor signaling. Here, we describe a dual-function molecule consisting of a clinically relevant TLR9 agonist (CpG7909) and a STAT3 inhibitor in the form of a high-affinity decoy oligodeoxynucleotide (dODN). The CpG-STAT3dODN blocked STAT3 DNA binding and activity, thus reducing expression of downstream target genes, such as MYC and BCL2L1, in human and mouse lymphoma cells. We further demonstrated that injections (i.v.) of CpG-STAT3dODN inhibited growth of human OCI-Ly3 lymphoma in immunodeficient mice. Moreover, systemic CpG-STAT3dODN administration induced complete regression of the syngeneic A20 lymphoma, resulting in long-term survival of immunocompetent mice. Both TLR9 stimulation and concurrent STAT3 inhibition were critical for immune-mediated therapeutic effects, since neither CpG7909 alone nor CpG7909 co-injected with unconjugated STAT3dODN extended mouse survival. The CpG-STAT3dODN induced expression of genes critical to antigen-processing/presentation and Th1 cell activation while suppressing survival signaling. These effects resulted in the generation of lymphoma cell-specific CD8/CD4-dependent T cell immunity protecting mice from tumor rechallenge. Our results suggest that CpG-STAT3dODN as a systemic/local monotherapy or in combination with PD1 blockade can provide an opportunity for treating patients with B cell NHL.

Gene regulation and suppression of type I interferon signaling by STAT3 in diffuse large B cell lymphoma

STAT3 is constitutively activated in many cancers and regulates gene expression to promote cancer cell survival, proliferation, invasion, and migration. In diffuse large B cell lymphoma (DLBCL), activation of STAT3 and its kinase JAK1 is caused by autocrine production of IL-6 and IL-10 in the activated B cell-like subtype (ABC). However, the gene regulatory mechanisms underlying the pathogenesis of this aggressive lymphoma by STAT3 are not well characterized. Here we performed genome-wide analysis and identified 2,251 STAT3 direct target genes, which involve B cell activation, survival, proliferation, differentiation, and migration. Whole-transcriptome profiling revealed that STAT3 acts as both a transcriptional activator and a suppressor, with a comparable number of up- and down-regulated genes. STAT3 regulates multiple oncogenic signaling pathways, including NF-κB, a cell-cycle checkpoint, PI3K/AKT/mTORC1, and STAT3 itself. In addition, STAT3 negatively regulates the lethal type I IFN signaling pathway by inhibiting expression of IRF7, IRF9, STAT1, and STAT2 Inhibition of STAT3 activity by ruxolitinib synergizes with the type I IFN inducer lenalidomide in growth inhibition of ABC DLBCL cells in vitro and in a xenograft mouse model. Therefore, this study provides a mechanistic rationale for clinical trials to evaluate ruxolitinib or a specific JAK1 inhibitor combined with lenalidomide in ABC DLBCL.

STAT3 Expression and Activity are Up-Regulated in Diffuse Large B Cell Lymphoma of Dogs

Background

The Janus Kinase (JAK) and Signal Transducer and Activator of Transcription (STAT) pathways play important roles in the pathogenesis of diffuse large B cell lymphoma (DLBCL) in humans, and up‐regulated STAT3 expression and activity are associated with worse clinical outcome in humans. No studies have evaluated the JAK‐STAT signaling pathway in DLBCL of dogs.

Hypothesis

STAT3 pathway is deregulated in DLBCL in dogs. We aim to assess the expression, activation, and cellular localization of STAT3 and mitogen‐activated protein kinase ERK1/2 in DLBCL of dogs.

Animals

Forty‐three client‐owned dogs diagnosed with DLBCL by histopathology

Methods

Retrospective analysis of DLBCL in dogs, including patient characteristics and treatment, immunohistochemistry, and protein expressions by Western blot.

Results

A higher percentage of STAT3 and p‐STAT3 immunolabelled cells were observed in DLBCL of dogs when compared to normal canine lymph nodes. In STAT3 immunolabelled cells, STAT3 has higher nuclear expression in lymphoma samples than in normal or reactive lymph nodes. In addition to up‐regulated STAT3 expression and activation, mitogen‐activated kinase ERK1/2 activation is up‐regulated in DLBCL of dogs.

Conclusion and Clinical Importance

Compared with the normal canine lymph node, DLBCL of dogs has up‐regulated STAT3 pathway. Our results support future investigation of JAK inhibitors in the treatment of DLBCL in dogs.

DCZ3301, a novel cytotoxic agent, inhibits proliferation in diffuse large B-cell lymphoma via the STAT3 pathway

Diffuse large B-cell lymphoma (DLBCL) is the most common type of lymphoma in adults, characterized by a rapidly increasing painless mass. A novel compound, DCZ3301, was synthesized that exerted direct cytotoxicity against DLBCL cell lines. The effects of DCZ3301 on DLBCL cells in vitro and in vivo and the associated mechanisms were investigated. DCZ3301 inhibited the viability of DLBCL cell lines, even in the presence of protumorigenesis cytokines. Additionally, the compound induced apoptosis and cell cycle arrest at the G2/M phase by reducing mitochondrial membrane potential. DCZ3301 exerted an antitumor effect through modulation of Akt, extracellular signal-regulated kinases 1/2 (ERK1/2) and janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signaling pathways. Furthermore, DCZ3301 downregulates STAT3 phosphorylation by inhibiting Lck/Yes-related novel protein tyrosine kinase (Lyn) activation in DLBCL. A synergistic cytotoxic effect on DLBCL cells was observed upon combination of DCZ3301 with panobinostat. In vivo, intraperitoneal injection of xenograft mice with DCZ3301 resulted in reduced tumor volume. Our preliminary results collectively support the utility of the small-molecule inhibitor DCZ3301 as an effective novel therapeutic option for DLBCL that requires further clinical evaluation.

AKT Hyperactivation and the Potential of AKT-Targeted Therapy in Diffuse Large B-Cell Lymphoma

AKT signaling is important for proliferation and survival of tumor cells. The clinical significance of AKT activation in diffuse large B-cell lymphoma (DLBCL) is not well analyzed. Here, we assessed expression of phosphorylated AKT (p-AKT) in 522 DLBCL patients. We found that high levels of p-AKT nuclear expression, observed in 24.3% of the study cohort, were associated with significantly worse progression-free survival and Myc and Bcl-2 overexpression. However, multivariate analysis indicated that AKT hyperactivation was not an independent factor. miRNA profiling analysis demonstrated that 63 miRNAs directly or indirectly related to the phosphatidylinositol 3-kinase/AKT/mechanistic target of rapamycin pathway were differentially expressed between DLBCLs with high and low p-AKT nuclear expression. We further targeted AKT signaling using a highly selective AKT inhibitor MK-2206 in 26 representative DLBCL cell lines and delineated signaling alterations using a reverse-phase protein array. MK-2206 treatment inhibited lymphoma cell viability, and MK-2206 sensitivity correlated with AKT activation status in DLBCL cells. On MK-2206 treatment, p-AKT levels and downstream targets of AKT signaling were significantly decreased, likely because of the decreased feedback repression; Rictor and phosphatidylinositol 3-kinase expression and other compensatory pathways were also induced. This study demonstrates the clinical and therapeutic implications of AKT hyperactivation in DLBCL and suggests that AKT inhibitors need to be combined with other targeted agents for DLBCL to achieve optimal clinical efficacy.

Checkpoint inhibitors in hematological malignancies

Inhibitory molecules such as PD-1, CTLA-4, LAG-3, or TIM-3 play a role to keep a balance in immune function. However, many cancers exploit such molecules to escape immune surveillance. Accumulating data support that their functions are dysregulated in lymphoid neoplasms, including plasma cell myeloma, myelodysplastic syndrome, and acute myeloid leukemia. In lymphoid neoplasms, aberrations in 9p24.1 (PD-L1, PD-L2, and JAK2 locus), latent Epstein-Barr virus infection, PD-L1 3'-untranslated region disruption, and constitutive JAK-STAT pathway are known mechanisms to induce PD-L1 expression in lymphoma cells. Clinical trials demonstrated that PD-1 blockade is an attractive way to restore host's immune function in hematological malignancies, particularly classical Hodgkin lymphoma. Numerous clinical trials exploring PD-1 blockade as a single therapy or in combination with other immune checkpoint inhibitors in patients with hematologic cancers are under way. Although impressive clinical response is observed with immune checkpoint inhibitors in patients with certain cancers, not all patients respond to immune checkpoint inhibitors. Therefore, to identify best candidates who would have excellent response to checkpoint inhibitors is of utmost importance. Several possible biomarkers are available, but consensus has not been made and pursuit to discover the best biomarker is ongoing.

Targeting the programmed death-1 pathway in lymphoid neoplasms

Programmed death-1 (PD-1) is a co-inhibitory molecule and is seen in CD4+ and CD8+ T cells. Upon binding to its ligands, programmed death ligand-1 (PD-L1) and -2 (PD-L2), PD-1 negatively regulates interleukin 2 (IL-2) production and T cell proliferation. Activated effector T-cells, which kill cancer cells, can be affected by PD-1 signaling in some lymphoid neoplasm that express PD-L1 or PD-L2. PD-L1 expression in tumor cells can be induced by extrinsic signal (i.e. interferon gamma) or intrinsic signals, such as genetic aberrations involving 9p24.1, latent Epstein-Barr virus infection, PD-L1 3'- untranslated region disruptions, and activated Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway. Anti-PD-1 therapy improves the overall response rate to treatment in patients with lymphoid neoplasms, particularly relapsed/refractory classical Hodgkin lymphoma. Inspired by their success in treating patients with classical Hodgkin lymphoma, medical practitioners have expanded PD-1 therapy, given as a single therapy or in combination with other drugs, to patients with other types of lymphoma. In this review, current clinical trials with anti-PD-1 or anti-PD-L1 drugs are summarized. The results of numerous clinical trials will broaden our understanding of PD-1 pathway and shall expand the list of patients who will get benefit from these agents including those who suffer from lymphoid neoplasms.

Stratifying diffuse large B-cell lymphoma patients treated with chemoimmunotherapy: GCB/non-GCB by immunohistochemistry is still a robust and feasible marker

Diffuse large B cell lymphoma (DLBCL) is a heterogeneous group of aggressive lymphomas that can be classified into three molecular subtypes by gene expression profiling (GEP): GCB, ABC and unclassified. Immunohistochemistry-based cell of origin (COO) classification, as a surrogate for GEP, using three available immunohistochemical algorithms was evaluated in TMA-arranged tissue samples from 297 patients with de novo DLBCL treated by chemoimmunotherapy (R-CHOP and R-CHOP-like regimens). Additionally, the prognostic impacts of MYC, BCL2, IRF4 and BCL6 abnormalities detected by FISH, the relationship between the immunohistochemical COO classification and the immunohistochemical expression of MYC, BCL2 and pSTAT3 proteins and clinical data were evaluated. In our series, non-GCB DLBCL patients had significantly worse progression-free survival (PFS) and overall survival (OS), as calculated using the Choi, Visco-Young and Hans algorithms, indicating that any of these algorithms would be appropriate for identifying patients who require alternative therapies to R-CHOP. Whilst MYC abnormalities had no impact on clinical outcome in the non-GCB subtype, those patients with isolated MYC rearrangements and a GCB-DLBCL phenotype had worse PFS and therefore might benefit from novel treatment approaches.

Prognostic impact of concurrent MYC and BCL6 rearrangements and expression in de novo diffuse large B-cell lymphoma

Double-hit B-cell lymphoma is a common designation for a group of tumors characterized by concurrent translocations of MYC and BCL2, BCL6, or other genes. The prognosis of concurrent MYC and BCL6 translocations is not well known. In this study, we assessed rearrangements and expression of MYC, BCL2 and BCL6 in 898 patients with de novo diffuse large B-cell lymphoma treated with standard chemotherapy (cyclophosphamide, doxorubicin, vincristine, and prednisone plus rituximab). Neither BCL6 translocation alone (more frequent in activated B-cell like diffuse large B-cell lymphoma) nor in combination with MYC translocation (observed in 2.0% of diffuse large B-cell lymphoma) predicted poorer survival in diffuse large B-cell lymphoma patients. Diffuse large B-cell lymphoma patients with MYC/BCL6 co-expression did have significantly poorer survival, however, MYC/BCL6 co-expression had no effect on prognosis in the absence of MYC/BCL2 co-expression, and had no additive impact in MYC⁺/BCL2⁺ cases. The isolated MYC⁺/BCL6⁺/BCL2⁻ subset, more frequent in germinal center B-cell like diffuse large B-cell lymphoma, had significantly better survival compared with the isolated MYC⁺/BCL2⁺/BCL6⁻ subset (more frequent in activated B-cell like diffuse large B-cell lymphoma). In summary, diffuse large B-cell lymphoma patients with either MYC/BCL6 rearrangements or MYC/BCL6 co-expression did not always have poorer prognosis; MYC expression levels should be evaluated simultaneously; and double-hit B-cell lymphoma needs to be refined based on the specific genetic abnormalities present in these tumors.

p63 expression confers significantly better survival outcomes in high-risk diffuse large B-cell lymphoma and demonstrates p53-like and p53-independent tumor suppressor function

The role of p53 family member, p63 in oncogenesis is the subject of controversy. Limited research has been done on the clinical implications of p63 expression in diffuse large B-cell lymphoma (DLBCL). In this study, we assessed p63 expression in de novo DLBCL samples (n=795) by immunohistochemistry with a pan-p63-monoclonal antibody and correlated it with other clinicopathologic factors and clinical outcomes. p63 expression was observed in 42.5% of DLBCL, did not correlate with p53 levels, but correlated with p21, MDM2, p16^INK4A, Ki-67, Bcl-6, IRF4/MUM-1 and CD30 expression, REL gains, and BCL6 translocation. p63 was an independent favorable prognostic factor in DLBCL, which was most significant in patients with International Prognostic Index (IPI) >2, and in activated-B-cell–like DLBCL patients with wide-type TP53. The prognostic impact in germinal-center-B-cell–like DLBCL was not apparent, which was likely due to the association of p63 expression with high-risk IPI, and potential presence of ∆Np63 isoform in TP63 rearranged patients (a mere speculation). Gene expression profiling suggested that p63 has both overlapping and distinct functions compared with p53, and that p63 and mutated p53 antagonize each other. In summary, p63 has p53-like and p53-independent functions and favorable prognostic impact, however this protective effect can be abolished by TP53 mutations.

Emodin alleviates jejunum injury in rats with sepsis by inhibiting inflammation response

Emodin is an anthraquinone derived from Chinese herb that exerts anti-inflammation effects. This study aimed to investigate whether emodin provides the protection for jejunum injury by inhibiting inflammation. We established a model of sepsis caused by cecal ligation and puncture. Forty-eight male Wistar rats were divided into four groups (n=12). Jejunum injury was assessed by pathological examination. The activity of pJAK1/pSTAT3 and protein levels of Bcl-2 and Bax were detected by Western blot analysis. Inflammatory factors IL-6, TNF-α and procalcitonin were detected by ELISA. Apoptosis was detected by TUNEL. We found that emodin alleviated jejunum damage and apoptosis induced by sepsis and decreased the levels of IL-6, TNF-α and procalcitonin in septic rats. Furthermore, we observed that emodin increased the levels of pJAK1 and of pSTAT3, which were decreased in rats with sepsis. In addition, emodin enhanced the expression of Bcl-2 which was downregulated by sepsis and decreased the expression of Bax which was upregulated by sepsis. In conclusion, these results indicate that emodin suppresses inflammatory response induced by sepsis. Emodin activates JAK1/STAT3 signaling pathway and regulates Bcl-2 and Bax expression to protect the jejunum in rats with sepsis.

Loss of PRDM1/BLIMP-1 function contributes to poor prognosis of activated B-cell-like diffuse large B-cell lymphoma

PRDM1/BLIMP-1, a master regulator of plasma-cell differentiation, is frequently inactivated in activated B-cell-like (ABC) diffuse large B-cell lymphoma (DLBCL) patients. Little is known about its genetic aberrations and relevant clinical implications. A large series of patients with de novo DLBCL was effectively evaluated for PRDM1/BLIMP-1 deletion, mutation, and protein expression. BLIMP-1 expression was frequently associated with the ABC phenotype and plasmablastic morphologic subtype of DLBCL, yet 63% of the ABC-DLBCL patients were negative for BLIMP-1 protein expression. In these patients, loss of BLIMP-1 was associated with Myc overexpression and decreased expression of p53 pathway molecules. In addition, homozygous PRDM1 deletions and PRDM1 mutations within exons 1 and 2, which encode for domains crucial for transcriptional repression, were found to show a poor prognostic impact in patients with ABC-DLBCL but not in those with germinal center B-cell-like DLBCL (GCB-DLBCL). Gene expression profiling revealed that loss of PRDM1/BLIMP-1 expression correlated with a decreased plasma-cell differentiation signature and upregulation of genes involved in B-cell receptor signaling and tumor-cell proliferation. In conclusion, these results provide novel clinical and biological insight into the tumor-suppressive role of PRDM1/BLIMP-1 in ABC-DLBCL patients and suggest that loss of PRDM1/BLIMP-1 function contributes to the overall poor prognosis of ABC-DLBCL patients.

Genetic Landscapes of Relapsed and Refractory Diffuse Large B-Cell Lymphomas

PURPOSE

Relapsed or refractory diffuse large B-cell lymphoma (rrDLBCL) is fatal in 90% of patients, and yet little is known about its biology.

EXPERIMENTAL DESIGN

Using exome sequencing, we characterized the mutation profiles of 38 rrDLBCL biopsies obtained at the time of progression after immunochemotherapy. To identify genes that may be associated with relapse, we compared the mutation frequency in samples obtained at relapse to an unrelated cohort of 138 diagnostic DLBCLs and separately amplified specific mutations in their matched diagnostic samples to identify clonal expansions.

RESULTS

On the basis of a higher frequency at relapse and evidence for clonal selection, TP53, FOXO1, MLL3 (KMT2C), CCND3, NFKBIZ, and STAT6 emerged as top candidate genes implicated in therapeutic resistance. We observed individual examples of clonal expansions affecting genes whose mutations had not been previously associated with DLBCL including two regulators of NF-κB: NFKBIE and NFKBIZ We detected mutations that may be affect sensitivity to novel therapeutics, such as MYD88 and CD79B mutations, in 31% and 23% of patients with activated B-cell-type of rrDLBCL, respectively. We also identified recurrent STAT6 mutations affecting D419 in 36% of patients with the germinal center B (GCB) cell rrDLBCL. These were associated with activated JAK/STAT signaling, increased phospho-STAT6 protein expression and increased expression of STAT6 target genes.

CONCLUSIONS

This work improves our understanding of therapeutic resistance in rrDLBCL and has identified novel therapeutic opportunities especially for the high-risk patients with GCB-type rrDLBCL. Clin Cancer Res; 22(9); 2290-300. ©2015 AACR.

Clinical and biological significance of de novo CD5+ diffuse large B-cell lymphoma in Western countries

CD5 is a pan-T-cell surface marker and is rarely expressed in diffuse large B-cell lymphoma (DLBCL). Large-scale studies of de novo CD5+ DLBCL are lacking in Western countries. In this study by the DLBCL Rituximab-CHOP Consortium, CD5 was expressed in 5.5% of 879 DLBCL patients from Western countries. CD5+ DLBCL was associated with higher frequencies of >1 ECOG performance status, bone marrow involvement, central nervous system relapse, activated B-cell-like subtype, Bcl-2 overexpression, and STAT3 and NF-κB activation, whereas rarely expressed single-stranded DNA-binding protein 2 (SSBP2), CD30 or had MYC mutations. With standard R-CHOP chemotherapy, CD5+ DLBCL patients had significantly worse overall survival (median, 25.3 months vs. not reached, P< .0001) and progression-free survival (median, 21.3 vs. 85.8 months, P< .0001) than CD5- DLBCL patients, which was independent of Bcl-2, STAT3, NF-κB and the International Prognostic Index. Interestingly, SSBP2 expression abolished the prognostic significance of CD5 expression, suggesting a tumor-suppressor role of SSBP2 for CD5 signaling. Gene-expression profiling demonstrated that B-cell receptor signaling dysfunction and microenvironment alterations are the important mechanisms underlying the clinical impact of CD5 expression. This study shows the distinctive clinical and biological features of CD5+ DLBCL patients in Western countries and underscores important pathways with therapeutic implications.

Tetraspanin CD37 protects against the development of B cell lymphoma

Worldwide, B cell non-Hodgkin lymphoma is the most common hematological malignancy and represents a substantial clinical problem. The molecular events that lead to B cell lymphoma are only partially defined. Here, we have provided evidence that deficiency of tetraspanin superfamily member CD37, which is important for B cell function, induces the development of B cell lymphoma. Mice lacking CD37 developed germinal center-derived B cell lymphoma in lymph nodes and spleens with a higher incidence than Bcl2 transgenic mice. We discovered that CD37 interacts with suppressor of cytokine signaling 3 (SOCS3); therefore, absence of CD37 drives tumor development through constitutive activation of the IL-6 signaling pathway. Moreover, animals deficient for both Cd37 and Il6 were fully protected against lymphoma development, confirming the involvement of the IL-6 pathway in driving tumorigenesis. Loss of CD37 on neoplastic cells in patients with diffuse large B cell lymphoma (DLBCL) directly correlated with activation of the IL-6 signaling pathway and with worse progression-free and overall survival. Together, this study identifies CD37 as a tumor suppressor that directly protects against B cell lymphomagenesis and provides a strong rationale for blocking the IL-6 pathway in patients with CD37- B cell malignancies as a possible therapeutic intervention.