A comprehensive case study on successful multimodal therapy in philadelphia chromosome-positive acute myeloid leukemia with NPM1 and IDH2 mutations

A 67-year-old female came to Tampa General Hospital with Philadelphia chromosome-positive (Ph+) acute myeloid leukemia (AML) featuring an intriguing combination of mutations, including NPM1 and IDH2 mutations. Novel combination therapy with azacitidine, venetoclax and ponatinib allowed her to successfully achieve a complete response (CR) and undergo an allogeneic hematopoietic stem cell transplant (HSCT). This case report provides an overview of her clinical course, emphasizing the significance of integrated therapy and the challenges associated with balancing treatment for AML. It also underscores the importance of a multidisciplinary approach and careful monitoring of patients with complex hematologic conditions.

Long-term follow up of the combination of ofatumumab, high-dose methylprednisolone, and lenalidomide for untreated chronic lymphocytic leukemia with biomarker analysis

BACKGROUND

Advancements in frontline therapy and chemotherapy-sparing treatments in chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) have altered the treatment algorithms of this disease. We present a frontline alternative for treatment- naïve (TN) CLL/SLL patients.

METHODS

This was a single-center, phase 2 study of high-dose methylprednisolone (HDMP) and ofatumumab with lenalidomide and ofatumumab consolidative therapy for all comers with TN CLL/SLL. Treatment was continued until disease progression or intolerable side effects. Patients were assessed for response per iwCLL 2008 criteria after completing cycles 3 and 12.

RESULTS

Forty-five patients were enrolled (median age, 62.6 years). High-risk features included del17p (18%), Del11q (22%), and unmutated IGHV gene (76%). Median treatment duration was 32·2 (2·7-75·9) months. Thirty-six patients discontinued treatment due to disease progression (22%), adverse events (40%), allogeneic hematopoietic cell transplantation (allo-HCT) (7%), consent withdrawal (4%), and secondary malignancies (7%). The best overall and complete response rates were 96& and 29% respectively. At median follow-up of 61·7 (5·6-84·9) months, 9 patients remained on treatment. Median progression-free survival was 54·4 (2·9-77·6) months. Three patients underwent allo-HCT after a median of 3 (3-4) treatment cycles. Treatment was well tolerated, with a grade 3/4 infusion reaction in one patient. The most common grade 3/4 hematological adverse event was neutropenia (69%). Four patients had grade 3/4 infections. No grade 3/4 tumor flares, tumor lysis syndrome, or thrombosis were observed.

CONCLUSION

The combination of ofatumumab, HDMP, and lenalidomide was effective and relatively well tolerated in treatment-naive CLL/SLL. Its role in the frontline setting remains unclear given the current available and effective treatment options.

FUNDING

The funders had no role in the study.

Plasma cell dependence on histone/protein deacetylase 11 reveals a therapeutic target in multiple myeloma

The clinical utility of histone/protein deacetylase (HDAC) inhibitors in combinatorial regimens with proteasome inhibitors for patients with relapsed and refractory multiple myeloma (MM) is often limited by excessive toxicity due to HDAC inhibitor promiscuity with multiple HDACs. Therefore, more selective inhibition minimizing off-target toxicity may increase the clinical effectiveness of HDAC inhibitors. We demonstrated that plasma cell development and survival are dependent upon HDAC11, suggesting this enzyme is a promising therapeutic target in MM. Mice lacking HDAC11 exhibited markedly decreased plasma cell numbers. Accordingly, in vitro plasma cell differentiation was arrested in B cells lacking functional HDAC11. Mechanistically, we showed that HDAC11 is involved in the deacetylation of IRF4 at lysine¹⁰³. Further, targeting HDAC11 led to IRF4 hyperacetylation, resulting in impaired IRF4 nuclear localization and target promoter binding. Importantly, transient HDAC11 knockdown or treatment with elevenostat, an HDAC11-selective inhibitor, induced cell death in MM cell lines. Elevenostat produced similar anti-MM activity in vivo, improving survival among mice inoculated with 5TGM1 MM cells. Elevenostat demonstrated nanomolar ex vivo activity in 34 MM patient specimens and synergistic activity when combined with bortezomib. Collectively, our data indicated that HDAC11 regulates an essential pathway in plasma cell biology establishing its potential as an emerging theraputic vulnerability in MM.

Response and resistance to CDK12 inhibition in aggressive B-cell lymphomas

Despite significant progress in the treatment of patients with diffuse large B-cell lymphoma (DLBCL) and mantle cell lymphoma (MCL), the prognosis of patients with relapsed disease remains poor due to the emergence of drug resistance and subsequent disease progression. Identification of novel targets and therapeutic strategies for these diseases represents an urgent need. Here, we report that both MCL and DLBCL are exquisitely sensitive to transcription-targeting drugs, in particular THZ531, a covalent inhibitor of cyclin-dependent kinase 12 (CDK12). By implementing pharmacogenomics and a cell-based drug screen, we found that THZ531 leads to inhibition of oncogenic transcriptional programs, especially the DNA damage response pathway, MYC target genes and the mTOR-4EBP1-MCL-1 axis, contributing to dramatic lymphoma suppression in vitro. We also identified de novo and established acquired THZ531-resistant lymphoma cells conferred by over-activation of the MEK-ERK and PI3K-AKT-mTOR pathways and upregulation of multidrug resistance-1 (MDR1) protein. Of note, EZH2 inhibitors reversed resistance to THZ531 by competitive inhibition of MDR1 and, in combination with THZ531, synergistically inhibited MCL and DLBCL growth in vitro. Our study indicates that CDK12 inhibitors, alone or together with EZH2 inhibitors, offer promise as novel effective approaches for difficult-to-treat DLBCL and MCL.

HDAC11 regulates expression of C/EBPβ and immunosuppressive molecules in myeloid-derived suppressor cells

Myeloid-derived suppressor cells (MDSCs) constitute a heterogeneous population of immature myeloid cells derived from bone marrow and negatively regulate both innate and adaptive immunity in the tumor microenvironment. Previously we have demonstrated that MDSCs lacking histone deacetylase 11 (HDAC11) displayed an increased suppressive activity against CD8+ T-cells. However, the mechanisms of HDAC11 that contribute to the suppressive function of MDSCs remain unclear. Here, we show that arginase activity and NO production is significantly higher in HDAC11 knockout MDSCs when compared with wild-type (WT) controls. In the absence of HDAC11, elevated arginase level and enzymatic activity were observed preferentially in the tumor-infiltrated granulocytic MDSCs, whereas iNOS expression and NO production were increased in the tumor-infiltrated monocytic MDSCs. Of note and for the first time, we demonstrated an association between the elevated expression of immunosuppressive molecules with up-regulation of the transcription factor C/EBPβ in MDSCs lacking HDAC11. Interestingly, the highest expression of C/EBPβ was observed among CD11b+ Gr-1+ MDSCs isolated from tumor-bearing mice. The additional demonstration that HDAC11 is recruited to the promoter region of C/EBPβ in WT MDSCs suggests a novel molecular mechanism by which HDAC11 influence the expression of immunosuppressive molecules in MDSCs through regulation of C/EBPβ gene expression.

Transcriptional programming drives Ibrutinib-resistance evolution in mantle cell lymphoma

Ibrutinib, a bruton's tyrosine kinase (BTK) inhibitor, provokes robust clinical responses in aggressive mantle cell lymphoma (MCL), yet many patients relapse with lethal Ibrutinib-resistant (IR) disease. Here, using genomic, chemical proteomic, and drug screen profiling, we report that enhancer remodeling-mediated transcriptional activation and adaptive signaling changes drive the aggressive phenotypes of IR. Accordingly, IR MCL cells are vulnerable to inhibitors of the transcriptional machinery and especially so to inhibitors of cyclin-dependent kinase 9 (CDK9), the catalytic subunit of the positive transcription elongation factor b (P-TEFb) of RNA polymerase II (RNAPII). Further, CDK9 inhibition disables reprogrammed signaling circuits and prevents the emergence of IR in MCL. Finally, and importantly, we find that a robust and facile ex vivo image-based functional drug screening platform can predict clinical therapeutic responses of IR MCL and identify vulnerabilities that can be targeted to disable the evolution of IR.

Targeting Macrophages as a Therapeutic Option in Coronavirus Disease 2019

Immune cells of the monocyte/macrophage lineage are characterized by their diversity, plasticity, and variety of functions. Among them, macrophages play a central role in antiviral responses, tissue repair, and fibrosis. Macrophages can be reprogrammed by environmental cues, thus changing their phenotype during an antiviral immune response as the viral infection progresses. While M1-like macrophages are essential for the initial inflammatory responses, M2-like macrophages are critical for tissue repair after pathogen clearance. Numerous reports have evaluated the detrimental effects that coronaviruses, e.g., HCoV-229E, SARS-CoV, MERS-CoV, and SARS-CoV-2, have on the antiviral immune response and macrophage functions. In this review, we have addressed the breadth of macrophage phenotypes during the antiviral response and provided an overview of macrophage-coronavirus interactions. We also discussed therapeutic approaches to target macrophage-induced complications, currently under evaluation in clinical trials for coronavirus disease 2019 patients. Additionally, we have proposed alternative approaches that target macrophage recruitment, interferon signaling, cytokine storm, pulmonary fibrosis, and hypercoagulability.

HDAC6 Plays a Noncanonical Role in the Regulation of Antitumor Immune Responses, Dissemination, and Invasiveness of Breast Cancer

Despite the outstanding clinical results of immune checkpoint blockade (ICB) in melanoma and other cancers, clinical trials in breast cancer have reported low responses to these therapies. Current efforts are now focused on improving the treatment efficacy of ICB in breast cancer using new combination designs such as molecularly targeted agents, including histone deacetylase inhibitors (HDACi). These epigenetic drugs have been widely described as potent cytotoxic agents for cancer cells. In this work, we report new noncanonical regulatory properties of ultra-selective HDAC6i over the expression and function of epithelial-mesenchymal transition pathways and the invasiveness potential of breast cancer. These unexplored roles position HDAC6i as attractive options to potentiate ongoing immunotherapeutic approaches. These new functional activities of HDAC6i involved regulation of the E-cadherin/STAT3 axis. Pretreatment of tumors with HDAC6i induced critical changes in the tumor microenvironment, resulting in improved effectiveness of ICB and preventing dissemination of cancer cells to secondary niches. Our results demonstrate for the first time that HDAC6i can both improve ICB antitumor immune responses and diminish the invasiveness of breast cancer with minimal cytotoxic effects, thus departing from the cytotoxicity-centric paradigm previously assigned to HDACi. SIGNIFICANCE: Ultraselective HDAC6 inhibitors can reduce tumor growth and invasiveness of breast cancer by noncanonical mechanisms unrelated to the previously cytotoxic properties attributed to HDAC inhibitors.

Liver prometastatic reaction: Stimulating factors and responsive cancer phenotypes

Cancer is first a localized tissue disorder, whose soluble and exosomal molecules and invasive cells induce a host response providing the stromal components of the primary tumor microenvironment (TME). Once the TME is developed, cancer-derived molecules and cells can more efficiently spread out and a whole-body response takes place, whose pathophysiological changes may result in a paraneoplastic syndrome. Remote organ-specific prometastatic reactions may also occur at this time, facilitating metastatic activities of circulating tumor cells (CTCs) through premetastatic niche development at targeted organs. However, additional signaling factors from the inter-organ communication network involved in the pathophysiology and comorbidities of cancer patients may also regulate prometastatic reaction-stimulating effects of cancer and non-cancer tissue factors. This article provides a conceptual overview of our ongoing clinical research on the liver prometastatic reaction (LPR) of patients with colorectal cancer (CRC), their portal vein- and hepatic artery-driven LPR-Stimulating Factors (LPR-SF), and their resulting LPR-derived Metastasis-Stimulating Factors (LPR-MSF) acting on liver-invading CRC cells. In addition, we also provide new insights on the molecular subtyping of LPR-responsive cancer phenotypes in patients with CRC and melanoma; and on how to investigate and interpret the prometastatic infrastructure in the real pathophysiological context of patients with cancer undergoing surgical procedures and receiving pharmacological treatments with multiple side effects, including those affecting the LPR, its stimulating factors and responsive cancer phenotypes.

Secretome profiling identifies neuron-derived neurotrophic factor as a tumor-suppressive factor in lung cancer

Clinical and preclinical studies show tissue-specific differences in tumorigenesis. Tissue specificity is controlled by differential gene expression. We prioritized genes that encode secreted proteins according to their preferential expression in normal lungs to identify candidates associated with lung cancer. Indeed, most of the lung-enriched genes identified in our analysis have known or suspected roles in lung cancer. We focused on the gene encoding neuron-derived neurotrophic factor (NDNF), which had not yet been associated with lung cancer. We determined that NDNF was preferentially expressed in the normal adult lung and that its expression was decreased in human lung adenocarcinoma and a mouse model of this cancer. Higher expression of NDNF was associated with better clinical outcome of patients with lung adenocarcinoma. Purified NDNF inhibited proliferation of lung cancer cells, whereas silencing NDNF promoted tumor cell growth in culture and in xenograft models. We determined that NDNF is downregulated through DNA hypermethylation near CpG island shores in human lung adenocarcinoma. Furthermore, the lung cancer-related DNA hypermethylation sites corresponded to the methylation sites that occurred in tissues with low NDNF expression. Thus, by analyzing the tissue-specific secretome, we identified a tumor-suppressive factor, NDNF, which is associated with patient outcomes in lung adenocarcinoma.

High Red Cell Distribution Width is an Adverse Predictive and Prognostic Factor in Patients With Diffuse Large B-Cell Lymphoma Treated With Chemoimmunotherapy

INTRODUCTION

The red blood cell distribution width (RDW) is an easy-to-obtain laboratory value that has emerged as a potential prognostic factor in solid and hematologic malignancies.

PATIENTS AND METHODS

We evaluated 121 patients with de novo diffuse large B-cell lymphoma (DLBCL) treated with standard chemoimmunotherapy at our institution between 2010 and 2012. We categorized patients with high RDW (> 14.6%) and normal RDW (11.6%-14.6%). We fitted multivariate regression models for complete response (CR) and overall survival (OS).

RESULTS

Patients with high RDW were less likely to achieve CR to chemoimmunotherapy than patients with normal RDW (48% vs. 83%; P < .001). The 5-year OS rate for patients with high RDW was lower than in patients with normal RDW (51% vs. 79%; P = .001). In multivariate regression models, high RDW was independently associated with lower odds of achieving CR (odds ratio, 0.32; 95% confidence interval [CI], 0.12-0.83; P = .02) and with higher risk of death from any cause (hazard ratio [HR], 2.04; 95% CI, 1.03-4.02; P = .04) than normal RDW in patients with DLBCL treated with chemoimmunotherapy. High RDW remained an independent adverse factor for OS after adjustment for the International Prognostic Index and the National Comprehensive Cancer Network-International Prognostic Index scores with HR 2.20 (95% CI, 1.12-4.31; P = .02) and HR 2.67 (95% CI 1.28-5.59; P = .009), respectively.

CONCLUSION

High RDW appears to be an adverse predictive and prognostic factor in patients with de novo DLBCL treated with R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone).

Targeting MYC activity in double-hit lymphoma with MYC and BCL2 and/or BCL6 rearrangements with epigenetic bromodomain inhibitors

Double/triple-hit lymphomas (DHL/THL) account for 5–10% of diffuse large B cell lymphoma (DLBCL) with rearrangement of MYC and BCL2 and/or BCL6 resulting in MYC overexpression. Despite the poor prognosis of DHL, R-CHOP chemotherapy remains the treatment backbone and new targeted therapy is needed. We performed comprehensive cytogenetic studies/fluorescence in situ hybridization on DLBCL and Burkitt lymphoma cell lines (n = 11) to identify the DHL/THL DLBCL in vitro model. We identified MYC/IG in Raji and Ramos (single hit); MYC/IG-BCL2 (DHL) in DOHH2, OCI-LY1, SUDHL2, and OCI-LY10; MYC/IG-BCL2/BCL6 (THL) in VAL; and no MYC rearrangement in U2932 and HBL1 (WT-MYC). Targeting MYC in the DHL/THL DLBCLs through bromodomain extra-terminal inhibitors (BETi) (JQ1, I-BET, and OTX015) significantly (p < 0.05) reduced proliferation, similar to WT-MYC cells, accompanied by decreased MYC but not BCL2 protein. Moreover, BETi suppressed MYC transcription and decreased BRD4 binding to MYC promoter in DHL cells. CD47 and PD-L1 are immunoregulatory molecules often expressed on tumors and regulated by MYC. High levels of surface CD47 but not surface PD-L1 was observed in DHL/THL, which was reduced by JQ1 treatment. BETi in combination with Pan-HDAC inhibitor had a limited effect on survival of DHL/THL, while combination of BETi and BCL2 inhibitor (ABT-199) had a significant (p < 0.005) inhibitory effect on survival followed by BCL-XL inhibition. Overall, the data suggests that MYC-expressing DLBCLs are probably addicted to the MYC-oncogenic effect regardless of MYC rearrangements. In summary, we identified an in vitro model for DHL/THL DLBCLs and provide evidence for the therapeutic potential of BET inhibitor alone or in combination with BCL2 inhibitor.

BCL2 Amplicon Loss and Transcriptional Remodeling Drives ABT-199 Resistance in B Cell Lymphoma Models

Drug-tolerant "persister" tumor cells underlie emergence of drug-resistant clones and contribute to relapse and disease progression. Here we report that resistance to the BCL-2 targeting drug ABT-199 in models of mantle cell lymphoma and double-hit lymphoma evolves from outgrowth of persister clones displaying loss of 18q21 amplicons that harbor BCL2. Further, persister status is generated via adaptive super-enhancer remodeling that reprograms transcription and offers opportunities for overcoming ABT-199 resistance. Notably, pharmacoproteomic and pharmacogenomic screens revealed that persisters are vulnerable to inhibition of the transcriptional machinery and especially to inhibition of cyclin-dependent kinase 7 (CDK7), which is essential for the transcriptional reprogramming that drives and sustains ABT-199 resistance. Thus, transcription-targeting agents offer new approaches to disable drug resistance in B-cell lymphomas.

[Expressions and prognostic significance of PTEN and PD-1 protein in patients with classical Hodgkin's lymphoma]

目的

分析肿瘤免疫耐受信号通路的重要因子PD-1和PTEN在经典型霍奇金淋巴瘤（CHL）患者中的表达及其与患者临床特征和预后的相关性。

方法

回顾性分析2003年2月至2013年8月诊治的56例CHL患者的临床资料。采用免疫组织化学染色法检测CHL患者PD-1和PTEN蛋白的表达，采用原位杂交法检测EBV及EBV编码的小mRNA（EBER），并结合患者的临床特征与生存状态进行相关性分析。

结果

①56例患者中，男34例，女22例，中位年龄25（7~71）岁，PTEN阳性者11例（19.64%），PD-1阳性者14例（25.00%）。②PTEN和PD-1表达呈正相关（rs=0.320，P=0.016）；PTEN表达与Ann Arbor分期、IPS评分和有无大包块（≥5 cm）明显相关，PD-1仅与有无大包块相关（P值均<0.05）。③中位随访43（5~86）个月，多因素分析结果显示：年龄≥45岁（P<0.001）、IPS评分>2分（P=0.026）、EBER阳性（P=0.004）、PTEN蛋白高表达（P=0.035）是影响患者5年总生存的不良预后因素，也是影响5年无进展生存的不良预后因素（P值分别为0.007、0.014、0.002、0.024）。

结论

肿瘤免疫逃逸信号通路因子PTEN与CHL患者的预后相关，对CHL患者的预后判断有一定作用，同时也为CHL的免疫治疗提供了新思路和理论依据。

Recent advances and future directions in mantle cell lymphoma research: report of the 2018 mantle cell lymphoma consortium workshop

Mantle cell lymphoma (MCL) is an aggressive B-cell non-Hodgkin lymphoma characterized by the t(11;14) chromosomal translocation. This translocation most often results in overexpression of cyclin D1. MCL is clinically heterogeneous, outcomes are generally poor, and no standard treatment has been established. The recent approvals of ibrutinib and acalabrutinib have provided an additional therapeutic option; however, resistance has emerged as a significant issue and presents the need for more detailed studies of resistance mechanisms. Recent clinical trials have provided new perspectives on the relative efficacy and safety of various approaches for both transplant-eligible and transplant-ineligible patients. Multiple novel strategies are being evaluated in the treatment of MCL, including both targeted agents and cellular immunotherapies. At the Lymphoma Research Foundation's 13th MCL Workshop, researchers gathered to discuss research findings, clinical trial results, and future directions related to MCL, its biology, and its treatment. This report, which includes a summary of each presentation, aims to review recent findings in MCL research and highlight potential areas for future study.

PLK1 stabilizes a MYC-dependent kinase network in aggressive B cell lymphomas

Concordant activation of MYC and BCL-2 oncoproteins in double-hit lymphoma (DHL) results in aggressive disease that is refractory to treatment. By integrating activity-based proteomic profiling and drug screens, polo-like kinase-1 (PLK1) was identified as an essential regulator of the MYC-dependent kinome in DHL. Notably, PLK1 was expressed at high levels in DHL, correlated with MYC expression, and connoted poor outcome. Further, PLK1 signaling augmented MYC protein stability, and in turn, MYC directly induced PLK1 transcription, establishing a feed-forward MYC-PLK1 circuit in DHL. Finally, inhibition of PLK1 triggered degradation of MYC and of the antiapoptotic protein MCL-1, and PLK1 inhibitors showed synergy with BCL-2 antagonists in blocking DHL cell growth, survival, and tumorigenicity, supporting clinical targeting of PLK1 in DHL.

Loss of HDAC11 ameliorates clinical symptoms in a multiple sclerosis mouse model

In an animal model for multiple sclerosis, the absence of HDAC11 reduces clinical severity, spinal cord demyelination, and immune cell infiltration, suggesting that HDAC11 is a promising target for MS treatment.

Multiple sclerosis (MS) is a chronic, immune-mediated, demyelinating disease of the central nervous system (CNS). There is no known cure for MS, and currently available drugs for managing this disease are only effective early on and have many adverse side effects. Results from recent studies suggest that histone deacetylase (HDAC) inhibitors may be useful for the treatment of autoimmune and inflammatory diseases such as MS. However, the underlying mechanisms by which HDACs influence immune-mediated diseases such as MS are unclear. More importantly, the question of which specific HDAC(s) are suitable drug targets for the potential treatment of MS remains unanswered. Here, we investigate the functional role of HDAC11 in experimental autoimmune encephalomyelitis, a mouse model for MS. Our results indicate that the loss of HDAC11 in KO mice significantly reduces clinical severity and demyelination of the spinal cord in the post-acute phase of experimental autoimmune encephalomyelitis. The absence of HDAC11 leads to reduced immune cell infiltration into the CNS and decreased monocytes and myeloid DCs in the chronic progressive phase of the disease. Mechanistically, HDAC11 controls the expression of the pro-inflammatory chemokine C–C motif ligand 2 (CCL2) gene by enabling the binding of PU.1 transcription factor to the CCL2 promoter. Our results reveal a novel pathophysiological function for HDAC11 in CNS demyelinating diseases, and warrant further investigations into the potential use of HDAC11-specific inhibitors for the treatment of chronic progressive MS.

EBV-positive diffuse large B-cell lymphoma, not otherwise specified: 2018 update on diagnosis, risk-stratification and management

DISEASE OVERVIEW

Epstein Barr virus-positive (EBV+) diffuse large B-cell lymphoma (DLBCL), not otherwise specified (NOS) is an entity included in the 2016 WHO classification of lymphoid neoplasms. EBV+ DLBCL, NOS, is an aggressive B-cell lymphoma associated with chronic EBV infection, and a poor prognosis with standard chemotherapeutic approaches.

DIAGNOSIS

The diagnosis is made through a careful pathological evaluation. Detection of EBV-encoded RNA is considered standard for diagnosis; however, a clear cutoff for positivity has not been defined. The differential diagnosis includes plasmablastic lymphoma, DLBCL associated with chronic inflammation, primary effusion lymphoma, HHV8+ DLBCL, NOS, and EBV+ mucocutaneuos ulcer.

RISK-STRATIFICATION

The International prognostic index (IPI) and the Oyama score can be used for risk-stratification. The Oyama score includes age >70 years and presence of B symptoms. The expression of CD30 is emerging as a potential adverse, and targetable, prognostic factor.

MANAGEMENT

Patients with EBV+ DLBCL, NOS, should be staged and managed following similar guidelines than patients with EBV-negative DLBCL. EBV+ DLBCL, NOS, however, has a worse prognosis than EBV-negative DLBCL in the era of chemoimmunotherapy. There is an opportunity to study and develop targeted therapy in the management of patients with EBV+ DLBCL, NOS.

Abstract 4967: HDAC11 function as a transcriptional regulator in immature myeloid cells to myeloid-derived suppressor cells transition

In normal myelopoiesis, immature myeloid cells (IMCs) differentiate into macrophages, neutrophils or dendritic cells, a process that is tightly controlled by transcription factors and epigenetic regulators. However, under tumor burden, IMCs differentiate into myeloid derived suppressor cells (MDSCs) and with subsequent up-regulation of immune suppressive factors and a pro-tumor effect. In prior studies, we found that MDSCs from HDAC11 KO mice displayed an increased T-cell suppressive activity that was associated with a more aggressive tumor growth as compared to MDSCs from wild type control mice. Unlike MDSC's in which absence of HDAC11 is associated with a suppressive phenotype, T-cell lacking HDAC11 are hyper-reactive and endowed with strong antitumor activity. To assess which phenotype will be the dominant one in vivo, we performed adoptive immune cell transfer experiments of MDSC and/or T-cells from HDAC11 KO mice into C57BL/6 tumor-bearing mice. The transfer of HDAC11KO MDSCs was able to eliminate, at least partially, the anti-tumor effect elicited by the adoptive transfer of HDAC11KO T cells.

Mechanistically we have found that MDSCs lacking HDAC11 displayed up-regulation of expression and enzymatic activity of arginase 1 and Nos2, two enzymes that are crucial in regulating MDSCs suppressive function. The aberrant enzymatic activities of Arg1 and Nos2 in HDAC11KO MDSCs correlate with over-expression of the lineage-specific transcription factor C/EBPβ, which has been shown to be essential for the differentiation of functional MDSCs. Furthermore, ChIP analysis confirmed that HDAC11 is recruited to the C/EBPβ gene promoter where exerts a negative regulatory effect upon gene transcription.

Taken together, we have uncovered a previously unknown role for HDAC11 as a transcriptional regulator of MDSCs function. A better understanding of this novel role of HDAC11 in myeloid biology will lead to targeted epigenetic therapies to manipulate the suppressive effect of these immunoregulatory cells.

Citation Format: Jie Chen, Fengdong Cheng, Eva Sahakian, John Powers, Zi Wang, Alejandro Villagra, Javier Pinilla-Ibarz, Eduardo M. Sotomayor. HDAC11 function as a transcriptional regulator in immature myeloid cells to myeloid-derived suppressor cells transition [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4967.

Response and survival benefit with chemoimmunotherapy in Epstein-Barr virus-positive diffuse large B-cell lymphoma

Epstein-Barr virus (EBV)-positive diffuse large B-cell lymphoma (DLBCL) is a haematologic malignancy with poor prognosis when treated with chemotherapy. We evaluated response and survival benefits of chemoimmunotherapy in EBV-positive DLBCL patients. A total of 117 DLBCL patients were included in our retrospective analysis; 33 were EBV-positive (17 treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone [R-CHOP] and 16 with CHOP), and 84 were EBV-negative (all treated with R-CHOP). The outcomes of interest were complete response (CR) and overall survival (OS) in EBV-positive DLBCL patients (R-CHOP versus CHOP) and in DLBCL patients treated with R-CHOP (EBV-positive vs EBV-negative). There were no differences in the clinical characteristics between EBV-positive and EBV-negative DLBCL patients. Among EBV-positive DLBCL patients, R-CHOP was associated with higher odds of CR (OR 3.14, 95% CI 0.75-13.2; P = .10) and better OS (hazard ratio 0.30, 95% confidence interval [CI] 0.09-0.94; P = .04). There were no differences in CR rate (OR 0.52, 95% CI 0.18-1.56; P = .25) or OS (hazard ratio 0.93, 95% CI 0.32-2.67; P = .89) between EBV-positive and EBV-negative DLBCL patients treated with R-CHOP. Based on our study, the addition of rituximab to CHOP is associated with improved response and survival in EBV-positive DLBCL patients. Epstein-Barr virus status does not seem to affect response or survival in DLBCL patients treated with R-CHOP.

Essential role for histone deacetylase 11 (HDAC11) in neutrophil biology

Epigenetic changes in chromatin structure have been recently associated with the deregulated expression of critical genes in normal and malignant processes. HDAC11, the newest member of the HDAC family of enzymes, functions as a negative regulator of IL-10 expression in APCs, as previously described by our lab. However, at the present time, its role in other hematopoietic cells, specifically in neutrophils, has not been fully explored. In this report, for the first time, we present a novel physiologic role for HDAC11 as a multifaceted regulator of neutrophils. Thus far, we have been able to demonstrate a lineage-restricted overexpression of HDAC11 in neutrophils and committed neutrophil precursors (promyelocytes). Additionally, we show that HDAC11 appears to associate with the transcription machinery, possibly regulating the expression of inflammatory and migratory genes in neutrophils. Given the prevalence of neutrophils in the peripheral circulation and their central role in the first line of defense, our results highlight a unique and novel role for HDAC11. With the consideration of the emergence of new, selective HDAC11 inhibitors, we believe that our findings will have significant implications in a wide range of diseases spanning malignancies, autoimmunity, and inflammation.

A phase I trial of panobinostat with ipilimumab in advanced melanoma

9547

Background: Immune checkpoint blockade is standard therapy for advanced melanoma (MEL), yet not all patients (pts) benefit. Panobinostat (PAN), a pan inhibitor of class I, II, and IV histone deacetylases (HDAC) is immunomodulatory, decreases tumor associated inhibitory cytokines and inhibition of effector T-cells. This dose finding study aimed to determine the safety and efficacy of escalating doses of PAN combined with ipilimumab (IPI) in advanced MEL. Methods: Eligible pts with unresectable stage 3/4 MEL, up to 3 prior lines of therapy, and adequate laboratory values were treated with oral PAN 5mg thrice weekly (TIW) plus IPI at 3mg/kg IV every 3 weeks X 4 doses, followed by maintenance PAN until progression or intolerance. Using a modified Ji design, PAN dose escalation by 5mg was planned in 3-12 pt cohorts up to a maximum dose of 20mg TIW, without intra-pt dose escalation. Dose limiting toxicity (DLT) was assessed up to day 84 from start of therapy. Results: Seventeen pts (M/F: 13/4), median age 66 yrs (48, 80) were treated with a median of 4 cycles of IPI (1,4). Of 6 pts treated at PAN 5mg TIW, there was one DLT (G3 hydronephrosis). Eleven pts received PAN 10mg TIW; of 9 evaluable for DLT, there were 3 DLTs (G3 rash, G3 diarrhea, G4 thrombocytopenia) preventing further dose escalation. Other G3 toxicities included anemia, hypophysitis, diarrhea, fatigue (all n = 2); rash, colitis, nausea, dehydration, dizziness, hypotension, ↑ lipase, ↓ sodium, & ↑ glucose (all n = 1). Three pts had previous anti-PD1 therapy. The response rate was 12% (2 PRs) with 35% stable disease. One pt remains on PAN > 24m since start of therapy. Median progression free- and overall survival was 2.23m (95% CI,1.57, 5.8) and 20.97m (95% CI, 8.97, NR) respectively. Biomarker analysis from peripheral blood and limited tumor biopsies pre-and on treatment examining immunoregulatory markers, including EOMES promoter acetylation in T-cells from PAN are ongoing. Conclusions: At tolerated doses, PAN does not appear to increase response to standard IPI in advanced MEL. Biomarker analyses will inform if immunomodulation by PAM improves efficacy of IPI. Combinations with selective HDAC inhibitors may be more appropriate for future study. Supported by grant P50 CA168536, Moffitt Skin Cancer SPORE. Clinical trial information: NCT02032810.

Effect of metformin chemoprevention on metabolomics profiles in Li-Fraumeni Syndrome (LFS)

1556

Background: LFS is a highly-penetrant, autosomal dominant, cancer predisposition disorder characterized by early onset cancer; germline mutations in TP53are present in 70% of LFS. We previously observed metformin inhibition on mitochondrial function in LFS patients. Metformin may reduce TCA cycle and glycolytic intermediates during cellular transformation, indicating inhibition of complex I of the mitochondria. To further explore this, we performed untargeted metabolomics profiling on stored serum of study participants. To our knowledge, there are no previous studies of metabolomics profiling in LFS patients treated with metformin. Methods: Adult LFS patients (≥18 years old) were enrolled for 20 weeks. Metformin was initiated at 500 mg per day and increased in 500 mg dose increments every two weeks to a maintenance dose of 2000 mg of metformin. Patients were taken off metformin for the last six weeks of the study (week 20). Global biochemical profiles were determined in human serum samples collected in 21 patients, each providing one sample at baseline, week 14 (on 2000 mg metformin) and week 20 (off metformin). Metabolomics analyses were performed by Metabolon, Inc. Results: Treatment with metformin induced a strong metabolic signature of increased fatty acid beta-oxidation in LFS patients. Acylcarnitines, long chain fatty acids, and 3-hydroxy fatty acids were significantly elevated following metformin treatment. TCA cycle intermediates, aconitate, malate, and fumarate were also increased as were levels of ketone body 3-hydroxybutyrate (BHBA)indicating robust β-oxidation, presumably to support increased energy production via the TCA cycle. Clearance of metformin results in normalization of levels to comparable baseline values, indicating a causal role of metformin in these changes. Conclusions: Global metabolomics profiling suggests an increase in TCA cycle intermediates and a strong signature of fatty acid oxidation with metformin treatment in LFS, suggesting metformin effect on the mitochondria and TCA cycle is more dynamic than previously shown. LFS patients may have distinct metabolic profiles which may be altered by treatment with metformin. Funding: ASCO Young Investigator’s Award 2016. Clinical trial information: NCT01981525.

HDAC11 as a candidate therapeutic target in multiple myeloma

8029

Background: Histone deacetylase (HDAC) inhibitors (HDI) have a therapeutic niche in multiple myeloma (MM) due to their ability to salvage proteasome inhibitor and immunomodulatory drug responsiveness in refractory patients, thus raising interest in this therapeutic class. Selective HDI may further improve therapeutic efficacy. Methods: B cell lymphopoiesis was evaluated using Tg-HDAC11-eGFP mice expressing eGFP regulated by the HDAC11 promoter and congenic mouse strains deficient in HDAC11 expression globally (B6.HDAC11-/-) or targeted to the B cell lineage (CD19Cre.HDAC11-/-). Molecular and pharmacologic means were used to impair HDAC11 in established MM cell lines. Viability was measured by activated caspase-3, Annexin/PI (A/PI) staining, and CCK-8 viability assay. Subcellular localization changes induced by HDI and identification of the novel binding partner IRF4 were assessed by proximity ligation assay (PLA). Results: Profound eGFP increases in PC of Tg-HDAC11-eGFP mice suggest HDAC11 influences late stage B cell development. In addition, HDAC11 deficiency results in dramatically reduced PC in the bone marrow and periphery. PC depletion in CD19Cre.HDAC11-/-mice suggests activity inherent in B cells rather than via externally derived signals. Quisinostat (QS), an HDI with enhanced HDAC11 selectivity, showed dose-dependent cytotoxicity in 10 MM cell lines (EC50 1-10nM). This activity was synergistic with bortezomib (BTZ) and carfilzomib (CFZ) in RPMI-8226 cells, while synergism was amplified in the BTZ-resistant RPMI-8226-B25 cell line. Exposure of RPMI-8226 cells to QS decreased detection of nuclear, but not cytosolic, HDAC11. Targeted siRNA–mediated silencing of HDAC11 in RPMI-8226 cells activated caspase-3 and reduced viability by A/PI staining. PLA of MM cell lines showed a novel interaction between HDAC11 and IRF4, an essential regulator of PC differentiation and MM survival, unmasking a potential mechanism for HDAC11-induced cytotoxicity in MM. This interaction was disrupted by QS. Conclusions: We show that HDAC11 inhibition reduces MM cell survival in vitro. Furthermore, we identify IRF4 as a binding partner for HDAC11 and propose this interaction as a candidate mechanism regulating PC maturation and MM survival.

Recent advances and future directions in mantle cell lymphoma research: report of the 2016 mantle cell lymphoma consortium workshop

Mantle cell lymphoma (MCL) is an aggressive B-cell non-Hodgkin lymphoma typically associated with the t(11;14) chromosomal translocation, resulting in overexpression of cyclin D1. Although MCL is associated with clinical heterogeneity, outcomes are generally poor and no standard treatment has been established. However, the recent approval of ibrutinib provides a new therapeutic option. Moreover, recent clinical trials have provided new perspectives on the relative efficacy and safety of various approaches for both transplant-eligible and transplant-ineligible patients. Multiple novel strategies are being evaluated in the treatment of MCL, including both targeted agents and cellular immunotherapies. At the Lymphoma Research Foundation's 12th MCL Workshop, researchers gathered to discuss research findings, clinical trial results, and future directions related to MCL, its biology, and its treatment. This manuscript, which includes a summary of each presentation, aims to review recent findings in MCL research and highlight potential areas for future study.

Results of a phase II study of lenalidomide and rituximab for refractory/relapsed chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is an incurable disease in need of new therapeutic strategies. The immunomodulatory agent, lenalidomide, has shown activity as salvage therapy for CLL. In this phase II trial, we combined lenalidomide with rituximab in 25 patients (range, 41-79) with refractory/relapsed CLL. Lenalidomide was administered orally on escalating doses, with cycle 1 doses of 2.5mg daily on days 1-7, 5mg on days 8-14, and 10mg on days 15-21 followed by 7days off. On cycle 2 and beyond, lenalidomide was administered at 20mg daily on days 1-21. Rituximab was administered at 375mg/m(2) intravenously on a weekly basis for the first cycle starting on day 15 for 4 doses, with each cycle being 28days. Treatment was continued until disease progression or toxicity. Overall response rate was 45.8% on intent-to-treat and 61.1% in evaluable patients (all partial responses). Median time to treatment failure was 14.3 months for evaluable patients, and median overall survival was not reached. The most common grade 3/4 toxicity was neutropenia (72% of patients). The most common nonhematologic toxicity was infection (29% of patients). Lenalidomide combined with rituximab showed activity in heavily treated refractory CLL with an acceptable toxicity profile.

EBV-positive diffuse large B-cell lymphoma of the elderly: 2016 update on diagnosis, risk-stratification, and management

Epstein-Barr virus (EBV)-positive diffuse large B-cell lymphoma (DLBCL) of the elderly is a provisional entity included in the 2008 WHO classification of lymphoid neoplasms. It is a disease typically seen in the elderly and thought to be associated with chronic EBV infection and severe immunosuppression with a component of immunosenescence. Recent research, however, has suggested that EBV-positive DLBCL can be seen in younger, immunocompetent patients. The diagnosis of EBV-positive DLBCL of the elderly is made through a careful pathological evaluation. The differential diagnosis includes infectious mononucleosis (specifically in younger patients), lymphomatoid granulomatosis, Hodgkin lymphoma, and gray zone lymphoma, among others. Detection of EBV-encoded RNA (EBER) is considered standard for diagnosis; however, a clear cutoff for positivity has not been defined. The International Prognostic Index (IPI), and the Oyama score can be used for risk-stratification. The Oyama score includes age >70 years and presence of B symptoms. The expression of CD30 is emerging as a potential adverse, and targetable, prognostic factor. Patients with EBV-positive DLBCL should be staged and managed following similar guidelines than patients with EBV-negative DLBCL. It has been suggested, however, that EBV-positive patients have a worse prognosis than EBV-negative counterparts in the era of chemoimmunotherapy. There is an opportunity to study and develop targeted therapy in the management of patients with EBV-positive DLBCL.

Abstract A074: Selective Inhibition of HDAC6 augments T-cell central memory and enhances anti-tumor functions: Implications in TIL therapy

Histone deacetylases (HDACs) are a family of epigenetic modulators responsible for regulating gene expression. As key players in orchestrating both tumor and immune responses, HDACs have received attention for their possible role in cancer immunotherapy. While pan-HDAC inhibitors directly impact tumor growth, their broad targeting can be detrimental to the immune system. In this sense, HDAC selective inhibition becomes attractive as a strategy to minimize off-target effects. Here a novel role of targeting HDAC6 in T-cells with potential implications for melanoma immunotherapy is explored. Adoptive T-cell therapy is an effective treatment for metastatic melanoma, reaching objective clinical responses in half of patients undergoing tumor infiltration lymphocyte (TIL) therapy. However, lack of persistence of reactive T-cells is a major reason why patients fail to sustain long-term responses to treatment. The presence of T-cell memory populations is associated with prolonged responses to TIL. Herein we have shown that HDAC6-selective inhibition by ricolinostat increased the central memory phenotype of human CD4 and CD8 T-cells (p&lt;0.01 and p&lt;0.05, respectively), as indicated by CD45RO, CD45RA, CD62L and/or CCR7 surface markers. While a decrease in the naïve, effector and effector memory subsets occurred, no differences in cell viability were observed. Accordingly, similar ricolinostat-induced central memory enhancement was seen in CD4 and CD8 T-cells from the peripheral blood of melanoma patients (p&lt;0.01 and p&lt;0.05, respectively). Ultimately, ricolinostat led to accumulation of a central memory phenotype for TIL derived from various cell preparations (e.g. tumor digest, pre- and post-rapid expansion in vitro), with p values &lt;0.05. Intriguingly, Th2 cytokine production (i.e. IL-4 p&lt;0.01, IL-6 p&lt;0.001 and IL-10) was impaired in T-cells from melanoma patients treated with ricolinostat, while no differences occurred on IL-2, IFNg, TNF or IL-17a secretion. Functionally, TILs isolated from patient-derived melanoma fragments cultured in the presence of ricolinostat exhibited increased proportion of CD8 T-cells producing IFNg and CD107a cytolytic molecules (50% vs 35%, p&lt;0.05). Moreover, no negative impact on T-cell viability or proliferation was observed following ricolinostat treatment. No detrimental effects were observed in the yield of TIL from melanoma fragments. Cytotoxicity in vitro was also evaluated. Relative to a melanoma only control group, ricolinostat pre-treatment of TILs or concomitantly with tumor cells induced 70% killing of HLA matched melanoma cells, while control-treated TILs resulted in 50% cell death. In vivo, adoptive transfer of rocilinostat-treated murine T-cells improved the anti-melanoma effect in a B16F10 model (day 25 mean tumor volume 800 vs. 2200 cubic mm). Ex vivo characterization of the memory T-cell distribution in the lymph nodes demonstrated increased CD44+CD62L+ T-cells upon HDAC6-selective inhibition (CD8+ 32.8% vs 21.8%; CD4+ 4.71% vs 2.3%), suggesting a role of HDAC6 in the formation or distribution of memory CD4+ and CD8+ T-cells. The results suggest a positive impact of HDAC6-selective inhibition on TIL therapy and the resulting anti-melanoma response in vivo. While further dissection of molecular mechanism(s) is essential, the data described provide a rationale for targeting HDAC6 to augment melanoma immunotherapy.

Citation Format: Andressa Sodre Laino, David M. Woods, Amod Sarnaik, Jeffrey Weber, Eduardo M. Sotomayor. Selective Inhibition of HDAC6 augments T-cell central memory and enhances anti-tumor functions: Implications in TIL therapy. [abstract]. In: Proceedings of the CRI-CIMT-EATI-AACR Inaugural International Cancer Immunotherapy Conference: Translating Science into Survival; September 16-19, 2015; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(1 Suppl):Abstract nr A074.

Abstract A066: Histone deacetylase 11 is an epigenetic regulator of T-cell pro-inflammatory function and novel target for enhancing T-cell anti-tumor activity

The efficacy of immunotherapy is dependent on the ability of antigen-specific T-cells to mount a proper anti-tumor response while avoiding a plethora of immunosuppressive mechanisms. Unfortunately, these immunosuppressive mechanisms often overwhelm the T-cell response, resulting in patients failing to respond. Histone deacetylases (HDACs) are a family of epigenetic modifiers named for their ability to remove acetyl groups from lysine residues of histone tails, thereby regulating the chromatin structure and gene expression. Here we report that HDAC11, the most recently discovered HDAC, is a regulator of T-cell pro-inflammatory function. Previous reports have shown HDAC11 expression to be tissue restricted. Consequently, we compared expression levels of HDAC11 using an eGFP reporter mouse, in various immune cells. It was found that T-cells expressed relatively high levels of HDAC11. However, while resting T-cells, both central memory and naïve, had high levels of HDAC11 expression, effector or effector memory T-cells displayed lower levels. Additionally, T-cells experienced rapid down-regulation of HDAC11 upon activation. To expand upon these observations, the function of T-cells from HDAC11KO mice were investigated. Initial experiments revealed no gross changes in the numbers or maturation of T-cells. However, HDAC11KO mice displayed an increased percentage of central memory CD8+ T-cells (p&lt;0.05). Additionally, upon activation these T-cells were more apt to acquire effector status (p&lt;0.001). Upon activation, HDAC11KO T-cells demonstrated a robust increase in IL-2, TNF and IFNγ production (p&lt;0.01), but showed no differences in Th2 or Th17 cytokine production. These T-cells also expressed higher levels of the effector molecules granzyme B and perforin (p&lt;0.01). Moreover, post-activation, CD8+ T-cells lacking HDAC11 also displayed a higher percentage of proliferating cells, and more divisions of proliferating cells (p&lt;0.01). HDAC11KO T-cells displayed higher resistance to proliferative suppression by Tregs and failed to succumb to anergy in a high dose antigen model. Indeed, while OTII T-cells from mice injected with high dose OVA peptide displayed reduced levels of IFNγ production compared to cells from non-injected mice after rechallenge, HDAC11KO/OTII T-cells had an increase in IFNγ production. Mechanistically, T-cells devoid of HDAC11 did not appear to have differences in TCR signaling, but did express higher levels of the transcription factors EOMES and T-bet. Chromatin immunoprecipitation (ChIP) revealed higher basal levels of acetylation of these genes in HDAC11KO mice. ChIP analysis also revealed interactions of HDAC11 at the promoters of both EOMES and T-bet. In a graft vs. host disease (GvHD) model, HDAC11KO T-cells produced a more rapid onset of GvHD, and were able to do so with transfers of cell numbers below that able to induce GvHD using WT T-cells (p&lt;0.01). This GvHD was characterized by greater levels of IFNγ and TNF as well as increased T-cell expansion (p&lt;0.05). In a B16 melanoma model, adoptive transfer of HDAC11KO T-cells resulted in delayed tumor progression (p&lt;0.05) compared to WT T-cells. To begin investigating the clinical potential of these data, the expression levels of HDAC11 were investigated in melanoma tumor sections utilized to grow tumor infiltrating lymphocytes (TIL) for clinical trials of adoptive cell therapy. A reduced level of HDAC11 was found in tumor sections from those patients responding to TIL therapy compared to progressing patients (p&lt;0.01). Collectively, beyond demonstrating HDAC11 as a novel epigenetic regulator of T-cell pro-inflammatory function, these results highlight HDAC11 as a novel target for enhancing the efficacy of immunotherapy.

Citation Format: David M. Woods, Andressa L. Sodre, Karrune Woan, Alejandro Villagra, Amod Sarnaik, Jeffrey Weber, Eduardo M. Sotomayor. Histone deacetylase 11 is an epigenetic regulator of T-cell pro-inflammatory function and novel target for enhancing T-cell anti-tumor activity. [abstract]. In: Proceedings of the CRI-CIMT-EATI-AACR Inaugural International Cancer Immunotherapy Conference: Translating Science into Survival; September 16-19, 2015; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(1 Suppl):Abstract nr A066.

HDAC Inhibition Upregulates PD-1 Ligands in Melanoma and Augments Immunotherapy with PD-1 Blockade

Expression of PD-1 ligands by tumors and interaction with PD-1-expressing T cells in the tumor microenvironment can result in tolerance. Therapies targeting this coinhibitory axis have proven clinically successful in the treatment of metastatic melanoma, non-small cell lung cancer, and other malignancies. Therapeutic agents targeting the epigenetic regulatory family of histone deacetylases (HDAC) have shown clinical success in the treatment of some hematologic malignancies. Beyond direct tumor cell cytotoxicity, HDAC inhibitors have also been shown to alter the immunogenicity and enhance antitumor immune responses. Here, we show that class I HDAC inhibitors upregulated the expression of PD-L1 and, to a lesser degree, PD-L2 in melanomas. Evaluation of human and murine cell lines and patient tumors treated with a variety of HDAC inhibitors in vitro displayed upregulation of these ligands. This upregulation was robust and durable, with enhanced expression lasting past 96 hours. These results were validated in vivo in a B16F10 syngeneic murine model. Mechanistically, HDAC inhibitor treatment resulted in rapid upregulation of histone acetylation of the PD-L1 gene leading to enhanced and durable gene expression. The efficacy of combining HDAC inhibition with PD-1 blockade for treatment of melanoma was also explored in a murine B16F10 model. Mice receiving combination therapy had a slower tumor progression and increased survival compared with control and single-agent treatments. These results highlight the ability of epigenetic modifiers to augment immunotherapies, providing a rationale for combining HDAC inhibitors with PD-1 blockade.

Abstract 1338: Novel implications of histone deacetylase 6 selective inhibition in melanoma T-cell immunotherapy

Adoptive T-cell therapy is an effective treatment for metastatic melanoma, achieving objective clinical responses in half of patients undergoing tumor infiltration lymphocyte (TIL) therapy. Epigenetic modifications are key players in regulating gene expression. Modulation of histone deacetylases (HDACs) has received attention for its implications in altering gene regulation. While HDAC pan-inhibition directly affects tumor growth, the immune system may be negatively impacted. Novel HDAC-selective inhibitors can ameliorate these undesirable effects. HDAC6 is unique in containing two catalytic domains, allowing for the development of isotype-selective inhibitors. Here a novel role of HDAC6 in T-cell immunity with important implications for adoptive cell therapy was explored. Initially a delay in B16 melanoma growth was observed in HDAC6KO mice (p&lt;0.001 at day 19). Furthermore, tumor-free HDAC6KO mice vaccinated with melanoma antigen peptides displayed a mean of 30% antigen-specific circulating CD8+ T-cells versus 12% in WT mice. Moreover, HDAC6 expression was reduced over three fold in T-cells activated in vitro. To further investigate the role(s) of HDAC6 in anti-tumor T-cell responses, the HDAC6 selective inhibitor rocilinostat was utilized. Adoptive transfer of rocilinostat-treated T-cells conferred an increased anti-melanoma response in a B16 model (day 25 mean tumor volume 800 vs. 2200 cubic mm), characterized by accumulation of central memory T-cells in the lymph nodes. To directly address the clinical potential of targeting HDAC6, T-cells from healthy human donors and melanoma patient-derived TILs were treated with rocilinostat. A modest but consistent 5% increase in central memory phenotype in healthy CD4+ and CD8+ T-cells was observed. While a decrease in the naïve, effector and effector memory subsets occurred, no differences in cell viability were seen. Rocilinostat treatment of TILs derived from different cell preparations (e.g. tumor digest, pre- and post-rapid expansion in vitro) displayed up to a three-fold increase in central memory in three patients analyzed. Impressively, repeated in vitro treatment with rocilinostat further increased the proportion of central memory CD4+ and CD8+ T-cells. Intriguingly, initial results show that the transcription factor T-BET, involved in T-cell function, was upregulated in TILs after rocilinostat treatment and in vitro expansion. Functionally, activation of rocilinosat-treated TILs resulted in increased IFNg+CD107a+ T-cells. Ultimately, rocilinostat pre-treatment of TILs or concomitantly with tumor resulted in 70% killing of HLA matched melanoma cells, compared to 50% killing by control-treated TILs, both relative to melanoma only control. These preliminary data provide a rationale for targeting HDAC6 in T-cells to improve cancer immunotherapy.

Citation Format: Andressa Sodre Laino, David M. Woods, Amod Sarnaik, Esteban Celis, Jeffrey Weber, Eduardo M. Sotomayor. Novel implications of histone deacetylase 6 selective inhibition in melanoma T-cell immunotherapy. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1338. doi:10.1158/1538-7445.AM2015-1338

Abstract 257: Class I HDAC inhibition upregulates PD-1 ligands in melanoma and increases the efficacy of PD-1 blockade

Ligation of co-inhibitory molecules such as PD-L1/PD-1 are known mechanisms of tumor escape. Blockade of this specific pathway with antibodies against PD-1 has proven effective in the treatment of metastatic melanoma, with response rates of 30-40% (Topalian, SL et al. 2012). However, since the majority of patients fail to respond, approaches to augment the efficacy of this approach are needed. We report herein that histone deacetylase (HDAC) inhibitors against class I HDACs generate robust and durable upregulation of PD-L1 and PD-L2 in melanoma cell lines as well as patient tumor samples. Combining the HDAC inhibitor LBH589 with PD-1 blockade in a murine melanoma model results in delayed tumor growth and increased survival, superior to either single agent. Initially, we evaluated the expression of PD-L1 by flow cytometry on several melanoma cell lines treated with the HDAC inhibitors LBH589, MS275 and MGCD0103. At 72 hours, all treatments resulted in increased PD-L1 surface expression. As a follow-up, additional inhibitors and time points were assessed. Upregulation was seen at 24 hours after treatment and continued past 96 hours. However, these effects were not observed with HDAC6 or class IIa specific inhibitors. We then evaluated a larger panel of HDACi on several patient derived melanomas. We observed dose dependent upregulation with all inhibitors with inhibition of HDAC1, HDAC2 and/or HDAC3, but no impact of HDAC6, HDAC8 or class IIa specific inhibitors. Additionally, we observed low level, but consistent upregulation of PD-L2 in conjunction with PD-L1. These in vitro results were validated in vivo using a B16 murine melanoma model and patient xenografts in SCID mice. Chromatin immunoprecipitation analysis shows that treatment of melanoma with an HDAC inhibitor results in increased histone acetylation at the PD-L1 promoter. Previous studies have demonstrated PD-L1 regulation by STAT3 (Wolfle SJ et al. 2011), in addition to HDAC inhibitor alteration of STAT3 activation (Gupta M. et al 2012). We are currently evaluating alterations in STAT3 signaling in HDAC inhibitor treated melanoma. Given the anti-melanoma properties of LBH589 and its augmentation of immunogenicity previously reported by our group, combination therapy using PD-1 blocking antibodies with LBH589 was explored. Treatment of B16 melanoma-bearing C57BL/6 mice with the combination resulted in tumor progression delay (p = 0.01) compared to control and single agent treatments. Accompanying this tumor delay was an increase in overall survival (p = 0.03). These results highlight the ability of epigenetic modifying agents to augment immunogenicity and increase the efficacy of current immunotherapies. These results provide a strong rationale for combining LBH589 with PD-1 blockade for the treatment of metastatic melanoma.

Citation Format: David M. Woods, Andressa L. Sodre, Amod Sarnaik, Eduardo M. Sotomayor, Jeffrey Weber. Class I HDAC inhibition upregulates PD-1 ligands in melanoma and increases the efficacy of PD-1 blockade. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 257. doi:10.1158/1538-7445.AM2015-257

The neutrophil-to-lymphocyte ratio is an independent prognostic factor in patients with peripheral T-cell lymphoma, unspecified

Peripheral T-cell lymphoma (PTCL) encompasses a group of rare and aggressive lymphomas. PTCL, unspecified (PTCLU) is the most common subtype of PTCL, and carries a poor prognosis. The International Prognostic Index (IPI) and the Prognostic Index for PTCLU (PIT) scoring systems are powerful risk-stratification tools in patients with PTCL. The aim of this study was to evaluate whether the neutrophil-to-lymphocyte ratio (NLR) is a prognostic factor in PTCLU. We retrospectively studied 83 patients with diagnosis of PTCLU. In the univariate analysis, NLR ≥ 4 was associated with worse overall survival (HR 3.96, 95% CI 1.92-8.17; p < 0.001). In the multivariate analysis, NLR ≥ 4 was independently associated with worse overall survival after adjustment for the PIT score (HR 4.30, 95% CI 1.90-9.69; p < 0.001), and for the IPI score (HR 2.60, 95% CI 1. 12-6.04; p = 0.03). Our study suggests the NLR could be helpful in refining the survival prognostication in patients with PTCLU.

Flow cytometric identification of immunophenotypically aberrant T-cell clusters on skin shave biopsy specimens from patients with mycosis fungoides

OBJECTIVES

To assess the ability of flow cytometry (FC) to detect putative neoplastic T-cell subsets on skin shave biopsy (SSB) specimens from patients with mycosis fungoides (MF) and to study the immunophenotype of skin-infiltrating tumor cells in MF.

METHODS

SSB specimens from patients with suspected MF were bisected and submitted for both FC and routine histopathology. Six-dimensional gating strategies were applied to identify putative neoplastic cells, independently from their expected immunophenotype.

RESULTS

Aberrant T cells were detected by FC in 18 of 33 SBB specimens, of which all had clinicomorphologic features of MF. Of the remaining 15 SSB specimens, six had clinicomorphologic features of MF and nine were diagnosed with benign inflammatory dermatoses. Unexpectedly, CD26 was aberrantly overexpressed in 11 (73%) and lost in three (20%) of 15 SSB specimens from patients with MF where this antigen was evaluated. Other detected aberrancies included CD3 dim- (13/18 [72%]), CD7 dim- (15/18 [83%]), and CD4-/CD8- (3/18 [17%]).

CONCLUSIONS

FC is capable of identifying putative neoplastic cells on SSB specimens from patients with MF. Bright homogeneous CD26 expression is a common and previously undescribed immunophenotypic aberrancy on MF skin infiltrates.

Targeting histone deacetylase 6 mediates a dual anti-melanoma effect: Enhanced antitumor immunity and impaired cell proliferation

The median survival for metastatic melanoma is in the realm of 8-16 months and there are few therapies that offer significant improvement in overall survival. One of the recent advances in cancer treatment focuses on epigenetic modifiers to alter the survivability and immunogenicity of cancer cells. Our group and others have previously demonstrated that pan-HDAC inhibitors induce apoptosis, cell cycle arrest and changes in the immunogenicity of melanoma cells. Here we interrogated specific HDACs which may be responsible for this effect. We found that both genetic abrogation and pharmacologic inhibition of HDAC6 decreases in vitro proliferation and induces G1 arrest of melanoma cell lines without inducing apoptosis. Moreover, targeting this molecule led to an important upregulation in the expression of tumor associated antigens and MHC class I, suggesting a potential improvement in the immunogenicity of these cells. Of note, this anti-melanoma activity was operative regardless of mutational status of the cells. These effects translated into a pronounced delay of in vivo melanoma tumor growth which was, at least in part, dependent on intact immunity as evidenced by the restoration of tumor growth after CD4+ and CD8+ depletion. Given our findings, we provide the initial rationale for the further development of selective HDAC6 inhibitors as potential therapeutic anti-melanoma agents.

Abstract 643: The histone deacetylase inhibitor Quisinostat augments the anti-tumor reponses of T-cells: Implications in adoptive cell therapy

It has become increasingly clear that histone deacetylases (HDACs), a family of epigenetic modifiers, play intimate roles in both tumor and immune biology. Indeed, two HDAC inhibitors (HDACi) are FDA approved for the treatment of cutaneous T-cell leukemia, and various others are currently undergoing clinical trials for the treatment of both solid and hematological malignancies. Beyond direct anti-tumor effects, HDACi have shown pronounced abilities to augment the immunogenicity of tumor cells leading to an improved ant-tumor immune response. Furthermore, in addition to anti-tumor effects, several studies have demonstrated a profound ability of HDACi to tip the scale between tolerance and inflammation in antigen presenting cells, leading to enhanced T-cell activation. However, less well studied is the ability of HDACi to directly influence the function and fate of T-cells. Here we report that the HDACi JNJ-264-81585 (Quisinostat) is able to augment the pro-inflammatory phenotype of T-cells in vitro and in vivo. Quisinostat is a hydroxamic acid with potent sub-nanomolar inhibition of several HDACs, and reported anti-tumor activity. Here we report that Quisinostat has a potent HDAC inhibition in T-cells, with sub-nanomolar doses increasing histone 3 acetylation levels in a dose dependent manner. Intriguingly, when treated with Quisinostat in vitro, activated murine CD4+ and CD8+ T-cells produced significantly higher levels of the pro-inflammatory cytokines IL-2, IFN-g, and TNF. Concomitantly, treated T-cells produced decreased levels of IL-6 and IL-17. To determine the efficacy of Quisinostat at augmenting T-cell function in vivo, a novel T-cell adoptive transfer model was utilized. In this model syngeneic T-cells from B6.SJL mice were stained with the proliferation tracking dye CellTrace™ Violet and activated in the presence of Quisinostat, then subsequently adoptively transferred into sub-lethally irradiated C57BL/6 recipient mice. Analysis of proliferation of transferred T-cells showed that CD8+ T-cells treated with Quisinostat had significantly higher rates of proliferation than those treated with DMSO control. As well, in a result similar to that seen in vitro, adoptively transferred T-cells had skewing towards a predominantly CD8+ composition. Finally, T-cells treated with Quisinostat displayed a reconstitution advantage over DMSO treated cells, with higher percentages of transferred T-cells relative to endogenous T-cells. Collectively, these results demonstrate a profound and important ability of HDAC inhibition to modulate the T-cell response, highlighting a role of HDACi, particularly Quisinostat, in augmenting the efficacy of adoptive cell therapy, giving rationale for clinical investigation.

Citation Format: David M. Woods, Andressa L. Sodre, Jason B. Brayer, Eduardo M. Sotomayor. The histone deacetylase inhibitor Quisinostat augments the anti-tumor reponses of T-cells: Implications in adoptive cell therapy. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 643. doi:10.1158/1538-7445.AM2014-643

Abstract 4089: Histone deacetylase 6 (HDAC6) as a regulator of PD-L1 expression through STAT3 modulation in melanoma

In spite of the progress made in the understanding of the cell biology, genetics and immunology of melanoma, the outcome for patients with advanced-stage disease has remained poor with a median survival ranging from 2-16 months. Some optimism was recently provided in metastatic melanoma by the improved clinical outcomes observed in patients receiving PD-L1 blocking antibodies. A better understanding of the environmental, genetic and epigenetic factors limiting the efficacy of melanoma immunotherapy will provide appropriate partner(s) for combination with Ipilimumab or PD1/PDL1 antibodies. Among the epigenetic factors, we have found that one member of the histone deacetylase family, HDAC6, plays a critical role not only in the regulation of survival/apoptosis of melanoma cells but also in limiting their immunogenicity and recognition by immune effector cells. Particularly, we found a major role of HDAC6 as a modulator of the immunosuppresive STAT3/IL-10 pathway and down-regulation of tolerogenic PD-L1 molecules in melanoma cells. By analyzing HDAC6 knock-down melanoma cell lines (HDAC6KD) we demonstrated the inactivation of the STAT3 pathway and the subsequent down-regulation of its target genes, including the expression of PD-L1. We also observed that the PD-L1 expression and phosphorylation of STAT3 was decreased in melanoma isolated from xenograph tumor growth models after in vivo treatment with specific HDAC6 inhibitors

Fortunately, there are multiple HDAC6-selective inhibitors available to mechanistically study the role of HDAC6 on these processes and provide a viable therapeutic avenue, which may minimize undesirable side effects that are characteristic of pan-HDACi such as SAHA. By building on our understanding of HDAC6 and applying these findings to novel experimental design, we hope to identify innovative therapeutic options to benefit cancer patients.

Citation Format: Maritza Lienlaf, Patricio Perez-Villarroel, Calvin Lee, Fengdong Cheng, Jorge Canales, Tessa Knox, Danay Marante, Amod Sarnaik, Pedro Horna, Ed. Seto, Keiran Smalley, Jeffrey S. Weber, Eduardo M. Sotomayor, Alejandro Villagra. Histone deacetylase 6 (HDAC6) as a regulator of PD-L1 expression through STAT3 modulation in melanoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4089. doi:10.1158/1538-7445.AM2014-4089

Abstract 4086: Histone deacetylase 6 (HDAC6) as a new target modulating the proliferation and immune-related pathways in melanoma

Histone deacetylases (HDACs), originally described as histone modifiers, have more recently been demonstrated to modify a variety of other proteins involved in diverse cellular processes unrelated to the chromatin environment. This includes the deacetylation of multiple non-histone targets, such as proteins involved in cell cycle/apoptosis and immune regulation. Specifically, HDACs have garnered significant interest due to the availability of drugs that selectively inhibits HDACs. We recently identified that the pharmacological or genetic abrogation of a single HDAC, HDAC6, modifies the immunogenicity and proliferation of melanoma in both in vitro and in vivo models.

Using specific HDAC6 inhibitors (HDAC6i) we observed decreased proliferation and G1 cell cycle arrest in all melanoma cell lines measured by MTS assay and flow cytometry. These results were also observed in stable HDAC6 knockdown melanoma cell lines (HDAC6KD) generated by specific lentiviral shRNA for HDAC6. In addition to the effects observed in proliferation and apoptosis after inhibiting HDAC6, we found important changes in the expression of immune-related pathways, including increased expression of MHC, co-stimulatory molecules, and specific melanoma tumor associated antigens such as gp100, MART-1, Tyrp1 and Tyrp2.

Our in vitro results were further supported by in vivo tumor growth studies. We observed a delayed tumor growth of inoculated B16 melanoma cells in C57BL/6 mice treated with selective HDAC6i. A similar outcome was identified after inoculation of HDAC6KD B16 melanoma cells in C57BL/6 mice. Such an effect was reverted partially in CD4+ and CD8+ depleted C57BL/6 mice challenged with HDAC6KD cells, suggesting that the disruption of HDAC6 enhances immune system recognition of melanoma cells. This delay in tumor growth could be a reflection of their diminished proliferation and an increase in their immunogenicity leading to improved immune recognition and clearance. These studies provide critical insights into the molecular pathways that are involved in the regulatory role of HDAC6 in cell proliferation, survival, and cytokine signaling of human melanoma cells. Collectively, our data has identified HDAC6 as an attractive therapeutic target in melanoma.

Citation Format: Patricio Perez-Villarroel, Maritza Lienlaf, Calvin Lee, Fengdong Cheng, David Woods, Kelly Barrios, Karrune Woan, Jorge Canales, Tessa Knox, Danay Marante, Hongwei Wang, Pedro Horna, Keiran Smalley, Esteban Celis, Ed Seto, Jeffrey S. Weber, Eduardo M. Sotomayor, Alejandro Villagra. Histone deacetylase 6 (HDAC6) as a new target modulating the proliferation and immune-related pathways in melanoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4086. doi:10.1158/1538-7445.AM2014-4086

Diagnostic immunophenotype of acute promyelocytic leukemia before and early during therapy with all-trans retinoic acid

OBJECTIVES

To study the immunophenotypic changes of acute promyelocytic leukemia (APL) in patients who recently received all-trans retinoic acid (ATRA) and to assess the diagnostic utility of flow cytometry in this setting.

METHODS

Flow cytometry was performed on 29 newly diagnosed APLs and 93 other acute myeloid leukemias, including 25 HLA-DR- or CD34- cases. Clinical notes from referring institutions were reviewed to assess for recent ATRA administration.

RESULTS

Recent ATRA therapy was documented in 17 (59%) of 29 patients with APL. The main features of untreated APL were preserved with ATRA therapy, including CD34- (83% vs 82%), HLA-DR- (83% vs 100%), and CD117+ (100% vs 77%). CD11b and CD11c were negative in all untreated APLs but positive in 76% and 88% of ATRA-treated APLs, respectively. Optimal diagnostic criteria for untreated APL (CD34- or HLA-DR- and CD11b- and CD11c-) showed 100% sensitivity and 98% specificity but were not useful after ATRA administration. The best interpretative approach to ATRA-treated APL (CD34- or HLA-DR-) showed 100% sensitivity but limited specificity (73%).

CONCLUSIONS

Information about recent ATRA administration is critical for adequate interpretation of the flow cytometric findings in patients with suspected APL.

Abstract 2564: Histone deacetylase 6 is a novel target for enhancing T-cell function during anti-tumor response and tumor-peptide vaccination

Histone deacetylases (HDACs) are a family of epigenetic regulators with emerging roles in both tumor and immune system biology. In particular, HDAC6 has been reported to modulate the acetylation HSP90, a regulator of regulatory T-cell (Treg) suppressive activity (de Zoeten, Mol Cel Biol, 2011). Here we report a novel role of HDAC6 in T-cell activation and response against tumor or peptide vaccine. Initially the relative expression of HDAC6 was evaluated in mouse and human T-cells, revealing decreased expression of this HDAC following CD3/CD28 stimulation. To further investigate the role(s) of HDAC6 in T-cell function, an HDAC6KO mouse model was utilized. Characterization of the T-cell compartments of the HDAC6KO mouse model showed a slight, but statistically significant increase in CD4+ T-cell population in the lymph nodes at the expense of a decreased percentage of CD8+ T-cells. Further investigation using isotype-specific HDAC6 inhibitors showed similar results when WT T-cells were activated and treated with an HDAC6 inhibitor. In addition to this population skewing, HDAC6 inhibition led to an enhanced expression of CD69 in WT CD4+ T-cells. This result was reproduced in human CD4+ T-cells, indicating a role of HDAC6 in regulating T-cell activation. To evaluate advantages of HDAC6 inhibition for tumor immunotherapy, melanoma-bearing mice were adoptively transferred with T-cells activated and treated with an HDAC6 inhibitor. Ex vivo analysis of memory T-cell distribution in the lymph nodes demonstrated an increased percent of CD44+CD62L+ T-cells upon HDAC6 inhibition, suggesting a role of HDAC6 in the formation or distribution of memory CD4+ and CD8+ T-cells. In a separate experiment, HDAC6KO mice inoculated with melanoma presented significantly delayed tumor growth. Additionally, in a tumor-peptide vaccination model, HDAC6KO mice displayed a remarkably reduced contraction phase in the antigen-specific CD8+ T-cell compartment when compared to WT mice after peptide vaccine administration. To further evaluate whether these in vivo responses were dependent on T-cells, WT or lympho-deficient, lymphoma-bearing mice were treated with an HDAC6 inhibitor. HDAC6 inhibition led to reduced tumor burden in WT mice, which was absent in lympho-deficient mice, highlighting the importance of lymphocytes in the aforementioned in vivo results. Thus, the role of HDAC6 in regulating immune cells during anti-tumor response appears to be more important than the previously reported role as a regulator of Treg function. The data presented demonstrates a positive effect of HDAC6 in T-cell activation, maintenance of anti-tumor response in vivo and persistence of reactive T-cells following peptide vaccination. The results herein described have revealed an unexplored role of HDAC6 with positive implications for cancer immunotherapy, warranting further investigation.

Citation Format: Andressa S. Laino, David M. Woods, Fengdong Cheng, HongWei Wang, Eduardo M. Sotomayor. Histone deacetylase 6 is a novel target for enhancing T-cell function during anti-tumor response and tumor-peptide vaccination. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2564. doi:10.1158/1538-7445.AM2014-2564