A Review of New Findings in Adult T-cell Leukemia-Lymphoma: A Focus on Current and Emerging Treatment Strategies

Bayesian sparse regression for exposure-response analyses of efficacy and safety endpoints to justify the clinical dose of valemetostat for adult T-cell leukemia/lymphoma

Valemetostat is an oral inhibitor of enhancer of zeste homolog (EZH) 2 and EZH1 approved in Japan for the treatment of adult T-cell leukemia/lymphoma (ATLL). To support the approved daily dose of 200 mg and inform dose adjustments in patients with ATLL, Bayesian exposure-response analyses were conducted using data from two clinical trials. The analyses included two efficacy endpoints, overall response by central and investigator assessments in patients with ATLL (n = 38, 150-200 mg), and six safety endpoints in patients with non-Hodgkin lymphoma (n = 102, 150-300 mg), which included grade ≥3 laboratory values for anemia, absolute neutrophil count decreased, and platelet count decreased; any grade ≥3 treatment-emergent adverse event (TEAE); and dose reductions and dose interruptions due to TEAEs. A slightly positive relationship was observed between unbound exposure and efficacy endpoints. A steeper relationship was observed in safety endpoints, compared with efficacy. Candidate covariate effects, except intercepts of the baseline laboratory values, were regularized via spike and slab priors in a Bayesian framework; only the laboratory values for corresponding hematologic TEAEs were shown to be of substantial impact. The target exposure range was established by defining a modified region of practical equivalence (184-887 ng·h/mL), which was expected to provide satisfactory efficacy and acceptable safety within the range of available exposure data. The simulated exposure range considering inter-individual variability showed that 200 mg could reach target exposure in the overall population and across subpopulations of interest, supporting the use of valemetostat 200 mg in patients with ATLL.

Tumor Antigens beyond the Human Exome

With the advent of immunotherapeutics, a new era in the combat against cancer has begun. Particularly promising are neo-epitope-targeted therapies as the expression of neo-antigens is tumor-specific. In turn, this allows the selective targeting and killing of cancer cells whilst healthy cells remain largely unaffected. So far, many advances have been made in the development of treatment options which are tailored to the individual neo-epitope repertoire. The next big step is the achievement of efficacious "off-the-shelf" immunotherapies. For this, shared neo-epitopes propose an optimal target. Given the tremendous potential, a thorough understanding of the underlying mechanisms which lead to the formation of neo-antigens is of fundamental importance. Here, we review the various processes which result in the formation of neo-epitopes. Broadly, the origin of neo-epitopes can be categorized into three groups: canonical, noncanonical, and viral neo-epitopes. For the canonical neo-antigens that arise in direct consequence of somatic mutations, we summarize past and recent findings. Beyond that, our main focus is put on the discussion of noncanonical and viral neo-epitopes as we believe that targeting those provides an encouraging perspective to shape the future of cancer immunotherapeutics.

Patient research priority setting partnership in human T-cell lymphotropic virus type I

INTRODUCTION

Human T-cell lymphotropic virus type 1 (HTLV-1) is a chronic infection affecting 5-10 million people worldwide. Ten percent develop HTLV-1-associated diseases, and 3%-5% develop HTLV-1-associated myelopathy (HAM)/tropical spastic paraparesis. Low health-related quality of life (HRQoL) is a significant concern for those with HTLV-1, and little is known about how it impacts daily life or what patients need from healthcare services. To address this, we report on patient involvement workshops aimed at identifying research priorities for HTLV-1 health service provision.

METHODS

Participants recruited through HTLV-1 clinics in England attended six 90-min virtual workshops over 10 months, and two 60-min consolidation workshops. Content developed iteratively from topic focussed group discussions. All workshops were video-recorded with consent, transcribed verbatim and thematically analysed. Using consensus voting rounds, participants individually ranked their top six and then collectively their top three research priorities from the themes inferred from the analysis. A final feedback session explored the experiences of participating in the workshops.

FINDINGS

Twenty-seven people with HTLV-1 engaged with the workshops with up to 22 participants attending each meeting. The majority were diagnosed with HAM (n = 22). The top three research priorities were identified as understanding disease progression, psychosocial wellbeing, and information and knowledge. Participants valued being asked to set research priorities that directly addressed their needs and enjoyed the workshops. They stressed the importance of patient advocates for promoting research that positively impacts everyday life.

CONCLUSION

This is the first of this type of research engagement with people with HTLV-1 in the United Kingdom. Participants identified several avenues of investigation that could lead to improvements in healthcare services and HRQoL. Participants believed the workshops signified the start of a conversation to progress person-centred and meaningful research in HTLV-1.

PATIENT OR PUBLIC CONTRIBUTION

People living with HTLV-1 were involved in the iterative design, conduct, analysis, writing and dissemination of this project through the patient involvement workshops. As a result of this engagement, a patient led advisory group has been set up to assist with the dissemination of the findings.

Lung Involvement in Adult T-Cell Lymphoma Diagnosed Using Bronchoscopic Cryobiopsy: A Case Report and Review of the Literature

The diagnosis of pulmonary lymphoma using small tissue samples is difficult and often requires surgical procedures; thus, a less invasive sampling method is desirable. Moreover, pulmonary involvement in adult T-cell lymphoma (ATL) is often difficult to diagnose, especially in cases without characteristic flower cells. Here, we present the case of a 78-year-old man, in whom pathological examination of the transbronchial lung biopsy (TBLB) specimen did not reveal malignant findings; therefore, transbronchial lung cryobiopsy (TBLC) in combination with endobronchial ultrasonography (EBUS) was used to diagnose ATL based on the pathological findings. A literature review identified 18 cases of pulmonary lymphomas diagnosed using TBLC. Among the 19 cases, including our own, 16 cases were of B-cell lymphoma (84.2%), and the present case is the first case of ATL diagnosed using TBLC. Eighty percent of the cases underwent a biopsy (more than two samples) of the middle or lower lobe and were diagnosed without major complications. EBUS was used with TBLC in three cases to identify the location of the pulmonary lesions. In the present case, EBUS was also useful for avoiding vascular biopsy. Although large-scale prospective studies are required to establish precise guidelines for diagnosing pulmonary lymphomas using TBLC, our case report and review contributes to a deeper understanding of the diagnosis of rare diseases.

Therapeutic approaches for HTLV-1-associated adult T-cell leukemia/lymphoma: a comprehensive review

Adult T-cell leukemia/lymphoma (ATLL), an infrequent malignancy resultant from human T-cell lymphotropic virus type I (HTLV-1), exhibits a spectrum of phenotypes, encompassing acute, smoldering, lymphomatous, and chronic variants, each bearing distinct clinical presentations. The preponderant acute manifestation is characterized by hypercalcemia, systemic manifestations, organomegaly, and dermatological eruptions. Conversely, the chronic phenotype is typified by lymphocytosis and/or cutaneous eruptions, while smoldering ATLL assumes an asymptomatic course. Immunocompromise afflicts ATLL patients, heightening their vulnerability to opportunistic infections that frequently intricately intertwine with disease progression. Therefore, an early diagnosis is crucial to manage the disease appropriately. While conventional chemotherapeutic regimens have shown limited success, especially in acute and lymphoma types, recent studies suggest that allogeneic stem cell transplantation might enhance treatment results because it has shown promising outcomes in some patients. Novel therapeutics, such as interferon and monoclonal antibodies, have also shown promise, but more research is needed to confirm their efficacy. Moreover, the identification of biomarkers for ATLL and genetic changes in HTLV-1 infected cells has led to the development of targeted therapies that have shown remarkable success in clinical trials. These targeted therapies have the potential to offer a more personalized approach to the treatment of ATLL. The aim of our review is to elaborate on conventional and novel therapies and the efficiency of mentioned treatments.

HTLV infection in blood donors from Mato Grosso do Sul state: a closer look at HTLV screening in Brazilian blood banks

Human T-lymphotropic virus (HTLV) infection has a worldwide distribution and currently, more than 2.5 million individuals have been infected in Brazil. The study aimed to investigate HTLV infection prevalence among blood donors in Mato Grosso do Sul, characterizing seroepidemiological profiles of HTLV-1/2 positive individuals and evaluating the blood bank's HTLV screening system. A cross-sectional survey was conducted among blood donors from Mato Grosso do Sul state (MS)-Central Brazil, between January to December 2021. The information was obtained from databases, samples from the collection of HEMOSUL, and active searching, with the completion of laboratory analyses. 35,278 blood donors were screened for anti-HTLV-1/2 by chemiluminescence immunoassay (CMIA). Among them, 78 were initially reactive for anti-HTLV-1/2 (2.21/1000). Out of 78, 67 returned to the blood center to collect a second sample for retesting with a second screening with CMIA. After confirmation, 8 samples were indeterminate, and 8 were confirmed as positive for HTLV antibodies. New tests were performed for the 8 positive samples, and 6 were confirmed as HTLV-1 infection (0.17/1,000), one as negative, and one as indeterminate. The present study describes the low prevalence of HTLV infection in blood donors from MS and contributes to the definition of the regional infection profile. The prevalence found in this study (0.017%-0.17/1000) shows to be a much lower value than the rates reported in other states in Brazil. We highlight the need for confirmatory testing for those seropositive donors in screening assays and the need for adequate counseling and patient management for those confirmed HTLV individuals.

Oncoviruses: How do they hijack their host and current treatment regimes

Viruses have the ability to modulate the cellular machinery of their host to ensure their survival. While humans encounter numerous viruses daily, only a select few can lead to disease progression. Some of these viruses can amplify cancer-related traits, particularly when coupled with factors like immunosuppression and co-carcinogens. The global burden of cancer development resulting from viral infections is approximately 12%, and it arises as an unfortunate consequence of persistent infections that cause chronic inflammation, genomic instability from viral genome integration, and dysregulation of tumor suppressor genes and host oncogenes involved in normal cell growth. This review provides an in-depth discussion of oncoviruses and their strategies for hijacking the host's cellular machinery to induce cancer. It delves into how viral oncogenes drive tumorigenesis by targeting key cell signaling pathways. Additionally, the review discusses current therapeutic approaches that have been approved or are undergoing clinical trials to combat malignancies induced by oncoviruses. Understanding the intricate interactions between viruses and host cells can lead to the development of more effective treatments for virus-induced cancers.

Zidovudine and Interferon Alfa based regimens for the treatment of adult T-cell leukemia/lymphoma (ATLL): a systematic review and meta-analysis

BACKGROUND

ATLL (Adult T-Cell Leukemia/Lymphoma) is an aggressive hematological malignancy. This T-cell non-Hodgkin lymphoma, caused by the human T-cell leukemia virus type 1 (HTLV-1), is challenging to treat. There is no known treatment for ATLL as of yet. However, it is recommended to use Zidovudine and Interferon Alfa-based regimens (AZT/IFN), chemotherapy, and stem cell transplant. This study aims to review the outcome of patients with different subtypes of ATLL treated with Zidovudine and Interferon Alfa-based regimens.

METHODS

A systematic search was carried out for articles evaluating outcomes of ATLL treatment by AZT/IFN agents on human subjects from January 1, 2004, until July 1, 2022. Researchers assessed all studies regarding the topic, followed by extracting the data. A random-effects model was used in the meta-analyses.

RESULTS

We obtained fifteen articles on the AZT/IFN treatment of 1101 ATLL patients. The response rate of the AZT/IFN regimen yielded an OR of 67% [95% CI: 0.50; 0.80], a CR of 33% [95% CI: 0.24; 0.44], and a PR of 31% [95% CI: 0.24; 0.39] among individuals who received this regimen at any point during their treatment. Our subgroup analyses' findings demonstrated that patients who received front-line and combined AZT/IFN therapy responded better than those who received AZT/IFN alone. It is significant to note that patients with indolent subtypes of disease had considerably higher response rates than individuals with aggressive disease.

CONCLUSION

IFN/AZT combined with chemotherapy regimens is an effective treatment for ATLL patients, and its use in the early stages of the disease may result in a greater response rate.

Shikonin Induces ROS-Dependent Apoptosis Via Mitochondria Depolarization and ER Stress in Adult T Cell Leukemia/Lymphoma

Adult T cell leukemia/lymphoma (ATLL) is an aggressive T-cell malignancy that develops in some elderly human T-cell leukemia virus (HTVL-1) carriers. ATLL has a poor prognosis despite conventional and targeted therapies, and a new safe and efficient therapy is required. Here, we examined the anti-ATLL effect of Shikonin (SHK), a naphthoquinone derivative that has shown several anti-cancer activities. SHK induced apoptosis of ATLL cells accompanied by generation of reactive oxygen species (ROS), loss of mitochondrial membrane potential, and induction of endoplasmic reticulum (ER) stress. Treatment with a ROS scavenger, N-acetylcysteine (NAC), blocked both loss of mitochondrial membrane potential and ER stress, and prevented apoptosis of ATLL cells, indicating that ROS is an upstream trigger of SHK-induced apoptosis of ATLL cells through disruption of the mitochondrial membrane potential and ER stress. In an ATLL xenografted mouse model, SHK treatment suppressed tumor growth without significant adverse effects. These results suggest that SHK could be a potent anti-reagent against ATLL.

An open-label, single-arm phase 2 trial of valemetostat for relapsed or refractory adult T-cell leukemia/lymphoma

Adult T-cell leukemia/lymphoma (ATL) is an aggressive non-Hodgkin lymphoma with poor prognosis and few treatment options for patients with relapsed, recurrent, or refractory disease. We evaluated the efficacy and safety of valemetostat, a potent enhancer of zeste homolog 2 (EZH2) and EZH1 inhibitor, in treating relapsed or refractory (R/R) ATL. This multicenter phase 2 trial enrolled patients with R/R aggressive ATL (acute, lymphoma, unfavorable chronic type). Patients received valemetostat 200 mg/day orally until progressive disease or unacceptable toxicity. The primary end point was overall response rate (ORR) centrally assessed by an independent efficacy assessment committee (IEAC). Secondary end points included best response in disease compartments, duration of response (DOR), pharmacokinetics, and safety. Twenty-five patients (median age, 69.0 years) with a median of 3 prior lines of therapy were enrolled; 24 had prior mogamulizumab treatment. The primary end point was met with a centrally reviewed ORR of 48.0% (90% confidence interval [CI], 30.5-65.9), including 5 complete and 7 partial remissions. Patients pretreated with mogamulizumab had an ORR of 45.8% (4 complete and 7 partial remissions). IEAC-assessed median DOR was not reached (NR) (95% CI, 1.87 to NR; months). Treatment-emergent adverse events (TEAEs) were manageable. TEAEs that occurred in ≥20% of patients included thrombocytopenia, anemia, alopecia, dysgeusia, neutropenia, lymphopenia, leukopenia, decreased appetite, and pyrexia. Grade ≥3 TEAEs included thrombocytopenia, anemia, lymphopenia, leukopenia, and neutropenia. Valemetostat demonstrated promising efficacy and tolerability in heavily pretreated patients, warranting further investigation in treating R/R ATL. This trial was registered at www.clinicaltrials.gov as #NCT04102150.

A decrease in newly diagnosed patients with adult T-cell leukemia/lymphoma in Kagoshima, a highly endemic area of HTLV-1 in southwestern Japan

Adult T-cell leukemia/lymphoma (ATL) is a peripheral T-cell malignancy caused by human T-cell leukemia virus type-I (HTLV-1). This study investigated whether the number of newly diagnosed patients with ATL is decreasing in the background of a declining number of individuals infected by HTLV-1 in Kagoshima, Japan, one of the most endemic areas of HTLV-1 in the world. We retrospectively analyzed the number of newly diagnosed patients with ATL between January 2001 and December 2021 in three major hospitals. The number of newly diagnosed patients with B-cell non-Hodgkin lymphoma (B-NHL) in the same period was examined as an internal control. One thousand eighteen and 2,029 patients with ATL and B-NHL were registered, respectively. The age-adjusted incidence of ATL steadily increased between 2001 and 2012, whereas that between 2013 and 2021 decreased. Despite the limitation of its retrospective nature, this is the first report indicating a decrease in ATL patients in Japan.

Map of thrombogenesis in viral infections and viral-driven tumours

Viruses are pathogenic agents responsible for approximately 10% of all human cancers and significantly contribute to the global cancer burden. Until now, eight viruses have been associated with the development of a broad range of malignancies, including solid and haematological tumours. Besides triggering and promoting oncogenesis, viral infections often go hand-in-hand with haemostatic changes, representing a potential risk factor for venous thromboembolism (VTE). Conversely, VTE is a cardiovascular condition that is particularly common among oncological patients, with a detrimental impact on patient prognosis. Despite an association between viral infections and coagulopathies, it is unclear whether viral-driven tumours have a different incidence and prognosis pattern of thromboembolism compared to non-viral-induced tumours. Thus, this review aims to analyse the existing evidence concerning the association of viruses and viral tumours with the occurrence of VTE. Except for hepatitis C virus (HCV) and human immunodeficiency virus (HIV) infection, which are associated with a high risk of VTE, little evidence exists concerning the thrombogenic potential associated with oncoviruses. As for tumours that can be induced by oncoviruses, four levels of VTE risk are observed, with hepatocellular carcinoma (HCC) and gastric carcinoma (GC) associated with the highest risk and nasopharyngeal carcinoma (NPC) associated with the lowest risk. Unfortunately, the incidence of cancer-related VTE according to tumour aetiology is unknown. Given the negative impact of VTE in oncological patients, research is required to better understand the mechanisms underlying blood hypercoagulability in viral-driven tumours to improve VTE management and prognosis assessment in patients diagnosed with these tumours.

HTLV-1 persistent infection and ATLL oncogenesis

Human T-cell leukemia virus type 1 (HTLV-1) is an oncogenic retrovirus; whereas HTLV-1 mainly persists in the infected host cell as a provirus, it also causes a malignancy called adult T-cell leukemia/lymphoma (ATLL) in about 5% of infection. HTLV-1 replication is in most cases silent in vivo and viral de novo infection rarely occurs; HTLV-1 rather relies on clonal proliferation of infected T cells for viral propagation as it multiplies the number of the provirus copies. It is mechanistically elusive how leukemic clones emerge during the course of HTLV-1 infection in vivo and eventually cause the onset of ATLL. This review summarizes our current understanding of HTLV-1 persistence and oncogenesis, with the incorporation of recent cutting-edge discoveries obtained by high-throughput sequencing.

Human oncogenic viruses: an overview of protein biomarkers in viral cancers and their potential use in clinics

INTRODUCTION

Although the idea that carcinogenesis might be caused by viruses was first voiced about 100 years ago, today's data disappointingly show that we have not made much progress in preventing and/or treating viral cancers in a century. According to recent studies, infections are responsible for approximately 13% of cancer development in the world. Today, it is accepted and proven by many authorities that Epstein-Barr virus (EBV), Hepatitis B virus (HBV), Hepatitis C virus (HCV), Human Herpesvirus 8 (HHV8), Human T-cell Lymphotropic virus 1 (HTLV1) and highly oncogenic Human Papillomaviruses (HPVs) cause or/and contribute to cancer development in humans.

AREAS COVERED

Considering the insufficient prevention and/or treatment strategies for viral cancers, in this review we present the current knowledge on protein biomarkers of oncogenic viruses. In addition, we aimed to decipher their potential for clinical use by evaluating whether the proposed biomarkers are expressed in body fluids, are druggable, and act as tumor suppressors or oncoproteins.

EXPERT OPINION

Consequently, we believe that this review will shed light on researchers and provide a guide to find remarkable solutions for the prevention and/or treatment of viral cancers.

HTLV infection in Brazil's second-largest indigenous reserve

Human T-lymphotropic viruses 1 and 2 (HTLV-1/2) have a worldwide distribution. HTLV-1 has been associated with several diseases, including an aggressive malignant disease known as adult T-cell leukemia/lymphoma and a chronic inflammatory neurological disease called HTLV-1-associated myelopathy, while HTLV-2 has not been definitively associated with diseases. HTLV-2 is most prevalent in specific groups such as injecting drug users and the indigenous population. In Brazil, most studies about HTLV in indigenous are carried out in indigenous communities from the north of the country. Mato Grosso do Sul (MS), Central Brazil, has the second-largest indigenous population in Brazil. However, there is no available data about HTLV infection in this group. We conducted the first investigation of HTLV-1/2 infection prevalence in the indigenous population from Jaguapiru and Bororó villages in Dourados City, MS, to provide the prevalence and molecular characterization of HTLV. For that, a total of 1875 indigenous participated in the study. All the serum samples were screened by an enzyme-linked immunosorbent assay commercial kit for the presence of anti-HTLV-1/2 antibodies. Positive samples were confirmed by HTLV-1/2 Western Blot assay. The HTLV-1 5’LTR region was detected by nested PCR amplification and sequenced by Sanger. Most of the study population declared belonging to Guarani-Kaiowá ethnicity (69.18%), 872 (46.51%), and 1003 (53.49%) were from Jaguapiru and Bororó villages, respectively. The median age of participants was 31 years, and 74.24% were females. Two individuals were detected with HTLV-1 (0.1%; CI 95% 0.1–0.2). The phylogenetic analysis revealed that isolates belong to the Cosmopolitan subtype and the Transcontinental subgroup (HTLV-1aA). The low HTLV-1 prevalence found in this study is similar to that observed among blood donors, and pregnant populations from Mato Grosso do Sul. The absence of HTLV-2 infection among these Brazilian indigenous communities would suggest a distinct behavior pattern from other indigenous populations in Brazil.

The endogenous HBZ interactome in ATL leukemic cells reveals an unprecedented complexity of host interacting partners involved in RNA splicing

Adult T-cell leukemia/lymphoma (ATL) is a T-cell lymphoproliferative neoplasm caused by the human T-cell leukemia virus type 1 (HTLV-1). Two viral proteins, Tax-1 and HBZ play important roles in HTLV-1 infectivity and in HTLV-1-associated pathologies by altering key pathways of cell homeostasis. However, the molecular mechanisms through which the two viral proteins, particularly HBZ, induce and/or sustain the oncogenic process are still largely elusive. Previous results suggested that HBZ interaction with nuclear factors may alter cell cycle and cell proliferation. To have a more complete picture of the HBZ interactions, we investigated in detail the endogenous HBZ interactome in leukemic cells by immunoprecipitating the HBZ-interacting complexes of ATL-2 leukemic cells, followed by tandem mass spectrometry analyses. RNA seq analysis was performed to decipher the differential gene expression and splicing modifications related to HTLV-1. Here we compared ATL-2 with MOLT-4, a non HTLV-1 derived leukemic T cell line and further compared with HBZ-induced modifications in an isogenic system composed by Jurkat T cells and stably HBZ transfected Jurkat derivatives. The endogenous HBZ interactome of ATL-2 cells identified 249 interactors covering three main clusters corresponding to protein families mainly involved in mRNA splicing, nonsense-mediated RNA decay (NMD) and JAK-STAT signaling pathway. Here we analyzed in detail the cluster involved in RNA splicing. RNAseq analysis showed that HBZ specifically altered the transcription of many genes, including crucial oncogenes, by affecting different splicing events. Consistently, the two RNA helicases, members of the RNA splicing family, DDX5 and its paralog DDX17, recently shown to be involved in alternative splicing of cellular genes after NF-κB activation by HTLV-1 Tax-1, interacted and partially co-localized with HBZ. For the first time, a complete picture of the endogenous HBZ interactome was elucidated. The wide interaction of HBZ with molecules involved in RNA splicing and the subsequent transcriptome alteration strongly suggests an unprecedented complex role of the viral oncogene in the establishment of the leukemic state.

Oral HDAC Inhibitor Tucidinostat (HBI-8000) in Patients with Relapsed or Refractory Adult T-cell Leukemia/Lymphoma: Phase IIb Results

This multicenter, prospective phase IIb trial evaluating the efficacy and safety of tucidinostat (HBI‐8000) in patients with relapsed or refractory (R/R) adult T‐cell leukemia/lymphoma (ATLL) was undertaken in Japan. Eligible patients had R/R ATLL and had failed standard of care treatment with chemotherapy and with mogamulizumab. Twenty‐three patients received tucidinostat 40 mg orally twice per week and were included in efficacy and safety analyses. The primary end‐point was objective response rate (ORR) assessed by an independent committee. The ORR was 30.4% (95% confidence interval [CI], 13.2, 52.9]. Median progression‐free survival was 1.7 months (95% CI, 0.8, 7.4), median duration of response was 9.2 months (95% CI, 2.6, not reached), and median overall survival was 7.9 months (95% CI, 2.3, 18.0). All patients experienced adverse events (AEs), which were predominantly hematologic and gastrointestinal. Incidence of grade 3 or higher AEs was 78.3%; most were laboratory abnormalities (decreases in platelets, neutrophils, white blood cells, and hemoglobin). Tucidinostat was well tolerated with AEs that could be mostly managed with supportive care and dose modifications. Tucidinostat is a meaningful treatment option for R/R ATLL patients; further investigation is warranted.

Triple combination of BET plus PI3K and NF-κB inhibitors exhibit synergistic activity in adult T cell leukemia/lymphoma

Triple combination of I-BET762, copanlisib, and bardoxolone methyl exhibits synergistic activity against ATL in vitro and in vivo.

Triple combination synergizes to inhibit c-MYC ex vivo in PBMCs containing leukemic cells from ATL patients.

Adult T-cell leukemia/lymphoma (ATL) is an aggressive T-cell lymphoproliferative malignancy caused by human T-cell leukemia virus type 1 (HTLV-1). ATL is an orphan disease with no curative drug treatment regimens urgently needing new combination therapy. HTLV-1-infected cells rely on viral proteins, Tax and HBZ (HTLV-1-b-ZIP factor), to activate the transcription of various host genes that are critical for promoting leukemic transformation. Inhibition of bromodomain and extraterminal motif (BET) protein was previously shown to collapse the transcriptional network directed by BATF3 super-enhancer and thereby induced ATL cell apoptosis. In the current work, by using xenograft, ex vivo, and in vitro models, we demonstrated that I-BET762 (BETi) synergized with copanlisib (PI3Ki) and bardoxolone methyl (NF-κBi) to dramatically decrease the growth of ATL cells. Mechanistically, the triple combination exhibited synergistic activity by down-regulating the expression of c-MYC while upregulating the level of the glucocorticoid-induced leucine zipper (GILZ). The triple combination also enhanced apoptosis induction by elevating the expression of active caspase-3 and cleaved PARP. Importantly, the triple combination prolonged the survival of ATL-bearing xenograft mice and inhibited the proliferation of ATL cells from peripheral blood mononuclear cells (PBMCs) of both acute and smoldering/chronic ATL patients. Therefore, our data provide the rationale for a clinical trial exploring the multiagent combination of BET, PI3K/AKT, and NF-κB inhibitors for ATL patients and expands the potential treatments for this recalcitrant malignancy.

Systematic review of survival outcomes for relapsed or refractory adult T-cell leukemia-lymphoma

Introduction

Adult T‐cell leukemia‐lymphoma (ATL) is a mature T‐cell lymphoproliferative neoplasm caused by human T‐cell leukemia virus type‐1 infection. There is no standard treatment for relapsed or refractory (r/r) ATL, and clinical outcomes are poor. This systematic review examined the survival outcomes for r/r ATL treated with various systemic therapies.

Methods

EMBASE and PubMed were searched for studies on r/r ATL, published between January 2010 and January 2020. The main outcome of interest was overall survival (OS). Median OS and an exploratory 30% OS time were assessed based on published data and Kaplan‐Meier curves.

Results

There were 21 unique treatment subgroups (from 14 studies), that met the eligibility criteria. Nine subgroups were mogamulizumab treatment, two were mogamulizumab prior to allogenic hematopoietic stem cell transplantation (allo‐HSCT), five were allo‐HSCT, and five were other chemotherapy. Respectively, the median OS and 30% OS varied considerably in range for mogamulizumab treatment (2.2–17.6 months and 8.7–27.1 months), allo‐HSCT (3.8–6.2 months and 7.5–19.8 months), and other chemotherapy arms (4.1–20.3 months and 7.1–17.0 months).

Conclusion

Mogamulizumab was the most frequently studied treatment regimen and can potentially provide longer survival compared with chemotherapy alone. Future comparisons with synthetic or historical control arms may enable clearer insights into treatment efficacy.

Combination of auraptene and arsenic trioxide induces apoptosis and cellular accumulation in the subG1 phase in adult T-cell leukemia cells

Objectives

Despite advances in the treatment of adult T-cell leukemia/lymphoma (ATLL), the survival rate of this malignancy remains significantly low. Auraptene (AUR) is a natural coumarin with broad-spectrum anticancer activities. To introduce a more effective therapeutic strategy for ATLL, we investigated the combinatorial effects of AUR and arsenic trioxide (ATO) on MT-2 cells.

Materials and Methods

The cells were treated with different concentrations of AUR for 24, 48, and 72 hr, and viability was measured by alamarBlue assay. Then, the combination of AUR (20 μg/ml) and ATO (3 μg/ml) was administrated and the cell cycle was analyzed by PI staining followed by flow cytometry analysis. In addition, the expression of NF-κB (REL-A), CD44, c-MYC, and BMI-1 was evaluated via qPCR.

Results

Assessment of cell viability revealed increased toxicity of AUR and ATO when used in combination. Our findings were confirmed by accumulation of cells in the sub G1 phase of the cell cycle and significant down-regulation of NF-κB (REL-A), CD44, c-MYC, and BMI-1.

Conclusion

Obtained findings suggest that combinatorial use of AUR and ATO could be considered for designing novel chemotherapy regimens for ATLL.

Tissue Pathogens and Cancers: A Review of Commonly Seen Manifestations in Histo- and Cytopathology

Tissue pathogens are commonly encountered in histopathology and cytology practice, where they can present as either benign mimickers of malignancy or true malignancies. The aim of this review is to provide a timely synthesis of our understanding of these tissue pathogens, with an emphasis on pertinent diagnostic conundrums associated with the benign mimickers of malignancy that can be seen with viral infections and those which manifest as granulomas. The oncogenic pathogens, including viruses, bacteria, and parasites, are then discussed with relationship to their associated malignancies. Although not exhaustive, the epidemiology, clinical manifestations, pathogenesis, and histological findings are included, along with a short review of emerging therapies.

Early Effects of HTLV-1 Infection on the Activation, Exhaustion, and Differentiation of T-Cells in Humanized NSG Mice

Adult T-cell leukemia/lymphoma (ATLL) is an aggressive malignancy of CD4+ T-cells associated with HTLV-1 infection. In this study, we used the model of immunodeficient NSG mice reconstituted with a functional human immune system (HIS) to investigate early events in HTLV-1 pathogenesis. Upon infection, human T-cells rapidly increased in the blood and lymphoid tissues, particularly CD4+CD25+ T-cells. Proliferation of CD4+ T-cells in the spleen and mesenteric lymph nodes (MLN) correlated with HTLV-1 proviral load and CD25 expression. In addition, splenomegaly, a common feature of ATLL in humans, was also observed. CD4+ and CD8+ T-cells predominantly displayed an effector memory phenotype (CD45RA-CCR7-) and expressed CXCR3 and CCR5 chemokine receptors, suggesting the polarization into a Th1 phenotype. Activated CD8+ T-cells expressed granzyme B and perforin; however, the interferon-γ response by these cells was limited, possibly due to elevated PD-1 expression and increased frequency of CD4+FoxP3+ regulatory T-cells in MLN. Thus, HTLV-1-infected HIS-NSG mice reproduced several characteristics of infection in humans, and it may be helpful to investigate ATLL-related events and to perform preclinical studies. Moreover, aspects of chronic infection were already present at early stages in this experimental model. Collectively, we suggest that HTLV-1 infection modulates host immune responses to favor viral persistence.

Dual cytoplasmic and nuclear localization of HTLV-1-encoded HBZ protein is a unique feature of adult T-cell leukemia

Adult T-cell leukemia-lymphoma (ATL), is a highly malignant T-cell neoplasm caused by human T-cell leukemia virus type 1 (HTLV-1), characterized by poor prognosis. Two viral proteins, Tax-1 and HTLV-1 basic-zipper factor (HBZ) play important roles in the pathogenesis of ATL. While Tax-1 can be found in both the cytoplasm and nucleus of HTLV-1 infected patients, HBZ is exclusively localized in the cytoplasm of HTLV-1 asymptomatic carriers and in patients with the chronic neurologic disease HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP). HBZ is only localized in the nucleus of ATL cell lines, suggesting that the nuclear localization of HBZ can be a hallmark of neoplastic transformation. In order to clarify this crucial point, we investigated in detail the pattern of HBZ expression in ATL patients. We made use of our monoclonal antibody 4D4-F3, that at present is the only reported reagent, among the few described, able to detect endogenous HBZ by immunofluorescence and confocal microscopy in cells from asymptomatic carriers, HAM/TSP and ATL patients. We found that HBZ is localized both in the cytoplasm and nucleus of cells of ATL patients irrespective of their clinical status, with a strong preference for the cytoplasmic localization. Also Tax-1 is localized in both compartments. As HBZ is exclusively localized in the cytoplasm in asymptomatic carriers and in non-neoplastic pathologies, this finding shows that neoplastic transformation consequent to HTLV-1 infection is accompanied and associated with the capacity of HBZ to translocate to the nucleus, which suggests a role of cytoplasmic-to-nuclear translocation in HTLV-1- mediated oncogenesis.

Updates in the Treatment of Peripheral T-Cell Lymphomas

Peripheral T-cell lymphomas (PTCLs) represent a heterogeneous group of rare hematologic malignancies accounting for less than 10% of non-Hodgkin lymphomas. The 2016 classification of World Health Organization recognized 29 different entities of PTCLs. These subgroups are characterized by different molecular and genetic patterns. For nearly 30 years, little improvement in the treatment of PTCLs has been noticed due to the paucity of randomized trials and anthracycline-based chemotherapy remains the mainstay of first-line treatment. In front-line setting, ECHELON-2, the first randomized controlled Phase III clinical trial, recently met its primary endpoint of PFS demonstrating the superiority of BV containing regimen when compared to standard CHOP in patients with CD30 positive PTCLs. The role of therapeutic intensifications such as autologous or allogenic stem cell transplantations remains controversial in first-line setting and in relapsed/refractory disease due to the lack of studies clearly addressing this question and the recently published negative studies. PTCLs are often refractory to first-line chemotherapy and tend to relapse after an initial response. New agents have been approved for relapsed/refractory disease such as Histone deacetylase inhibitors, folate analogue metabolic inhibitor or CD30 antibody drug conjugated. Despite an acceptable response to these agents, progression-free survival remains very poor. New strategies such as combinations of different agents have been evaluated in order to improve outcomes. Innovative drugs in the fields of epigenetics, immunomodulation within the tumor microenvironment, and direct targeting of tumor cells to CD30 and T-cell receptor abnormalities open new perspectives to improve the treatment of PTCLs.

PD-1 and PD-L1 inhibitors foster the progression of adult T-cell Leukemia/Lymphoma

Immunotherapy through immune checkpoints blockade and its subsequent clinical application has revolutionized the treatment of a spectrum of solid tumors. Blockade of Programmed cell death protein-1 and its ligand has shown promising results in clinical studies. The clinical trials that enrolled patients with different hematopoietic malignancies including non-Hodgkin lymphoma, Hodgkin lymphoma, and acute myeloid leukemia (AML) showed that anti-PD-1 agents could have potential therapeutic effects in the patients. Adult T-cell leukemia/lymphoma (ATLL) is a non-Hodgkin T-cell Lymphoma that is developed in a minority of HTLV-1-infected individuals after a long latency period. The inhibition of PD-1 as a treatment option is currently being investigated in ATLL patients. In this review, we present a summary of the biology of the PD-1/PD-L1 pathway, the evidence in the literature to support anti-PD-1/PDL-1 application in the treatment of different lymphoid, myeloid, and virus-related hematological malignancies, and controversies related to PD-1/PD-L1 blocking in the management of ATLL patients.

Latency Reversing Agents: Kick and Kill of HTLV-1?

Human T-cell leukemia virus type 1 (HTLV-1), the cause of adult T-cell leukemia/lymphoma (ATLL), is a retrovirus, which integrates into the host genome and persistently infects CD4⁺ T-cells. Virus propagation is stimulated by (1) clonal expansion of infected cells and (2) de novo infection. Viral gene expression is induced by the transactivator protein Tax, which recruits host factors like positive transcription elongation factor b (P-TEFb) to the viral promoter. Since HTLV-1 gene expression is repressed in vivo by viral, cellular, and epigenetic mechanisms in late phases of infection, HTLV-1 avoids an efficient CD8⁺ cytotoxic T-cell (CTL) response directed against the immunodominant viral Tax antigen. Hence, therapeutic strategies using latency reversing agents (LRAs) sought to transiently activate viral gene expression and antigen presentation of Tax to enhance CTL responses towards HTLV-1, and thus, to expose the latent HTLV-1 reservoir to immune destruction. Here, we review strategies that aimed at enhancing Tax expression and Tax-specific CTL responses to interfere with HTLV-1 latency. Further, we provide an overview of LRAs including (1) histone deacetylase inhibitors (HDACi) and (2) activators of P-TEFb, that have mainly been studied in context of human immunodeficiency virus (HIV), but which may also be powerful in the context of HTLV-1.

Successful treatment with brentuximab vedotin for relapsed and refractory adult T cell leukemia

Although treatments for adult T-cell leukemia/lymphoma in the past two decades have advanced, the current standard treatment for aggressive adult T-cell leukemia/lymphoma, particularly in patients who are not eligible for stem cell transplantation, remains inadequate; therefore, treatments to prolong the duration of remission and provide relevant benefits in terms of survival and quality of life are needed. Adult T-cell leukemia/lymphoma tumor cells express CD30 in some cases and the increased expression of CD30 is considered to be one of the causes of constitutive NF-κB activation in adult T-cell leukemia/lymphoma cells. Brentuximab vedotin represents a major breakthrough in the treatment of CD30-positive lymphomas. Elderly patients treated with chemotherapy generally have higher rates of grade 3 or 4 adverse events; however a retrospective analysis demonstrated the safety and efficacy of brentuximab vedotin in adults ≥60 years with relapsed and refractory CD30-positive lymphomas. We herein report the clinical effects of brentuximab vedotin and the significance of CD30 expression in an elderly refractory/relapse adult T-cell leukemia/lymphoma patient. CD30 expression is associated with disease progression in adult T-cell leukemia/lymphoma patients and brentuximab vedotin may be a new and promising treatment option for these patients. Further investigations on the use of brentuximab vedotin for adult T-cell leukemia/lymphoma are needed.

Drosophila as a Model for Infectious Diseases

The fruit fly, Drosophila melanogaster, has been used to understand fundamental principles of genetics and biology for over a century. Drosophila is now also considered an essential tool to study mechanisms underlying numerous human genetic diseases. In this review, we will discuss how flies can be used to deepen our knowledge of infectious disease mechanisms in vivo. Flies make effective and applicable models for studying host-pathogen interactions thanks to their highly conserved innate immune systems and cellular processes commonly hijacked by pathogens. Drosophila researchers also possess the most powerful, rapid, and versatile tools for genetic manipulation in multicellular organisms. This allows for robust experiments in which specific pathogenic proteins can be expressed either one at a time or in conjunction with each other to dissect the molecular functions of each virulent factor in a cell-type-specific manner. Well documented phenotypes allow large genetic and pharmacological screens to be performed with relative ease using huge collections of mutant and transgenic strains that are publicly available. These factors combine to make Drosophila a powerful tool for dissecting out host-pathogen interactions as well as a tool to better understand how we can treat infectious diseases that pose risks to public health, including COVID-19, caused by SARS-CoV-2.

Overexpression of aberrant Wnt5a and its effect on acquisition of malignant phenotypes in adult T-cell leukemia/lymphoma (ATL) cells

Wnt5a is a ligand of the non-canonical Wnt signaling pathway involved in cell differentiation, motility, and inflammatory response. Adult T-cell leukemia/lymphoma (ATL) is one of the most aggressive T-cell malignancies caused by infection of human T-cell leukemia virus type1 (HTLV-1). Among subtypes of ATL, acute-type ATL cells are particularly resistant to current multidrug chemotherapies and show remarkably high cell-proliferative and invasive phenotypes. Here we show a dramatic increase of WNT5A gene expression in acute-type ATL cells compared with those of indolent-type ATL cells. Treatment with IWP-2 or Wnt5a-specific knockdown significantly suppressed cell growth of ATL-derived T-cell lines. We demonstrated that the overexpression of c-Myb and FoxM1 was responsible for the synergistic activation of the WNT5A promoter. Also, a WNT5A transcript variant without the exon4 (the ΔE4-WNT5A mRNA), encoding ΔC-Wnt5 (1-136aa of 380aa), is overexpressed in acute-type ATL cells. The ΔC-Wnt5a is secreted extracellularly and enhances cellular migration/invasion to a greater extent compared with wildtype (WT)-Wnt5a. Moreover, the ΔC-Wnt5a secretion was not suppressed by IWP-2, indicating that this mutant Wnt5a is secreted via a different pathway from the WT-Wnt5a. Taken together, synergistic overexpression of the ΔC-Wnt5a by c-Myb and FoxM1 may be responsible for the malignant phenotype of acute-type ATL cells.

Chapter XX Antiviral Treatment and Cancer Control

Hepatitis B virus (HBV), hepatitis C virus (HCV), human papilloma virus (HPV), Epstein-Barr virus (EBV), human T-cell lymphotropic virus type 1 (HTLV-1), Kaposi's sarcoma-associated herpesvirus (KSHV), and Merkel cell polyomavirus (MCV) contribute to about 10-15% global burden of human cancers. Conventional chemotherapy or molecular target therapies have been used to treat virus-associated cancers. However, a more proactive approach would be the use of antiviral treatment to suppress or eliminate viral infections to prevent the occurrence of cancer in the first place. Antiviral treatments against chronic HBV and HCV infection have achieved this goal, with significant reduction in the incidence of hepatocellular carcinoma in treated patients. Antiviral treatments for EBV, KSHV, and HTLV-1 had limited success in treating refractory EBV-associated lymphoma and post-transplant lymphoproliferative disorder, KSHV-associated Kaposi's sarcoma in AIDS patients, and HTLV-1-associated acute, chronic, and smoldering subtypes of adult T-cell lymphoma, respectively. Therapeutic HPV vaccine and RNA interference-based therapies for treating HPV-associated infection or cervical cancers also showed some encouraging results. Taken together, antiviral therapies have yielded promising results in cancer prevention and treatment. More large-scale studies in a real-world setting are necessary to confirm the efficacy of antiviral therapy. Further investigation for more effective and convenient antiviral regimens warrants more attention.

Antitumor Effect of Sugar-Modified Cytosine Nucleosides on Growth of Adult T-Cell Leukemia Cells in Mice

Adult T-cell leukemia (ATL) is a CD4⁺ T-cell neoplasm caused by human T-cell leukemia virus type I. As the prognosis for patients with ATL remains extremely poor due to resistance to conventional chemotherapy regimens, introduction of novel therapeutic agents is needed. Previous studies have reported that nucleosides 2′-deoxy-2′-methylidenecytidine (DMDC) and its derivative 2′-deoxy-2′-methylidene-5-fluorocytidine (FDMDC) exhibit antitumor activities in T-cell acute lymphoblastic leukemia (T-ALL) and solid tumor cell lines. Another nucleoside, 1-(2-azido-2-deoxy-β-D-arabinofuranosyl)cytosine (cytarazid), is considered a therapeutic drug with antitumor activity in human solid tumors. In this study, we investigated the effects of these nucleosides on cell growth in vitro and in vivo using relevant leukemia cell lines and NOD/Shi-scid, IL-2Rg^null (NOG) mice, respectively. The nucleosides demonstrated significant cytotoxic effects in ATL and T-ALL cell lines. Intraperitoneal administration of FDMDC and DMDC into tumor-bearing NOG mice resulted in significant suppression of tumor growth without lethal side effects. Our findings support a therapeutic application of these nucleosides against tumor progression by targeting DNA polymerase-dependent DNA synthesis in patients with ATL.

The Antihelminthic Drug, Mebendazole, Induces Apoptosis in Adult T-Cell Leukemia/Lymphoma Cancer Cells: In-Vitro Trial

Background: Adult T-cell leukemia/lymphoma (ATLL) is a poor prognostic Hematopoietic malignancy with various therapeutic challenges, which had been classified as non-Hodgkin lymphoma. The Drug switching, as a novel, innovative and promising approach, is an opportunity to overcoming on therapeutic challenges of hard-treating disease, e.g. ATLL. Our aim is evaluating the antiproliferative and apoptotic effect of Mebendazole (MBZ) on ATLL cancer cells in in-vitro conditions.

Materials and Methods: We used Jurkat cell-line as ATLL cancer cells. After treatment of MBZ in different concentrations on jurkat cells, the cell viabilities were determined by MTT assay. After IC₅₀ value determination, the 24-, 48- and 72-h treatments had been performed in IC₅₀ concentration and control to evaluating the quantitative apoptosis rate by Annexin/PI Flowcytometry and qualitative apoptosis by DAPI Nuclear staining. Also, Glucose spectrophotometry were performed to evaluate the reduced amount of glucose uptake through MBZ treatment.

Results: MBZ inhibits proliferation of jurkat cells and IC₅₀ value had been estimated 10 μM (P< 0.01). According to the flowcytometric results, increasing in drug concentration is associated with decrease cell viability and the percentage of full-apoptosis. However, it inversely correlates with percentage of early-apoptosis rate. Also, the microscopic captures of DAPI Nuclear staining confirms the flowcytometry results in qualitative manner. In addition, it was found that inhibition of glucose uptake was inversely correlated with increased MBZ concentration (P< 0.05).

Conclusion: MBZ potentially inhibits the proliferation of ATLL cancer cells in in-vitro condition. MBZ inhibits the growth of Jurkat cells by inducing apoptosis. Also, we suggest that indirectly inhibition of Glucose transporting occurs by MBZ, which could induce apoptosis in cancer cells.

Mitogen-activated protein kinases are involved in cucurbitacin D-induced antitumor effects on adult T-cell leukemia cells

Adult T cell leukemia (ATL) is an aggressive and malignant blood disease. We previously reported that steroid-structured cucurbitacin D (CuD) induces apoptosis in ATL cells. In this study, we investigated the effects of mitogen-activated protein kinase (MAPK) signaling inhibitors on CuD-induced cell death in peripheral blood lymphocytes (PBLs) isolated from ATL/acute lymphoblastic leukemia (ALL) patients and two human leukemia cell lines (MT-1 and MT-4). PBLs were isolated from an ATL/ALL patient as well as from a healthy donor. Cell surface markers were examined using flow cytometry. Serum cytokine levels were estimated using LEGENDplex or analyzed at the Center for Clinical and Translational Research of Kyushu University Hospital. Cell proliferation was assessed using the Cell Titer-Glo luminescent cell viability assay. Protein expression was determined by western blotting. PBLs from patients highly expressed CD4 and CD5. Serum from the patient contained high levels of interleukin (IL)-8, IL-10, IL-18, and interferon-γ compared to the healthy donor. CuD-induced cell death was enhanced by the mitogen-activated protein kinase kinase (MEK)1/2 inhibitor U0126. However, a c-Jun N-terminal kinase (JNK) inhibitor prevented CuD-induced cell death. Immunoblot analyses revealed that CuD reduced the phosphorylation of extracellular signal-regulated kinase (ERK), p38, and JNK, and co-treatment with CuD and U0126 did not affect the phosphorylation of ERK. MEK1/2 and p38 inhibitors enhanced CuD-induced cell death, and U0126 enhanced the CuD-induced de-phosphorylation of ERK in MT-1 and MT-4 cells. We conclude that CuD reduces ERK activation, resulting in enhanced antitumor effects on leukemic cells.

MALT-1 as a novel therapeutic target for adult T-cell leukemia

OBJECTIVES

T-cell receptor (TCR) signaling-induced activation of NF-κB requires assembly of the CARD11-BCL10-MALT-1 complex and IκB kinase (IKK). Gain-of-function alterations in this component of the TCR/NF-κB pathway are associated with the development of HTLV-1-driven adult T-cell leukemia (ATL). We aimed to determine whether inhibition of MALT-1-mediated NF-κB activation could have anti-ATL activity.

METHODS

RT-PCR, immunoblotting, and electrophoretic mobility shift assays were performed to assess expression levels of MALT-1 and the intracellular signaling cascades. Cell proliferation, cell cycle progression, and apoptotic events were examined using WST-8 assays, flow cytometry, and Hoechst 33342 staining.

RESULTS

MALT-1 expression was upregulated in ATL-derived T-cell lines compared to that in normal PBMCs and uninfected or HTLV-1-transformed T-cell lines. Targeting MALT-1 with siRNA decreased cell proliferation. A MALT-1 inhibitor (MI-2) suppressed cleavage of the MALT-1-target protein, CYLD, and inhibited proliferation via G1 phase arrest. MI-2 induced apoptosis through caspase-3/8/9 activation and inhibited the phosphorylation of IKKα/β and IκBα, resulting in the accumulation of IκBα and suppression of NF-κB-DNA binding. Additionally, MI-2 inhibited the expression of apoptosis- and cell cycle-related proteins regulated by NF-κB.

CONCLUSIONS

MALT-1 plays an important regulatory role in NF-κB signaling during ATL-genesis, and targeting MALT-1 is a promising therapeutic strategy for this disease.

Emerging Evidence for Infectious Causes of Cancer in the United States

Worldwide, infectious agents currently contribute to an estimated 15% of new cancer cases. Most of these (92%, or 2 million new cancer cases) are attributable to 4 infectious agents: Helicobacter pylori, human papillomavirus, and hepatitis B and C viruses. A better understanding of how infectious agents relate to the US cancer burden may assist new diagnostic and treatment efforts. We review US-specific crude mortality rates from infection-associated cancers and describe temporal and spatial trends since 1999. We review the US-specific evidence for infection-cancer associations by reporting available estimates for attributable fractions for the infection-cancer associations. Death due to cancers with established infectious associations varies geographically, but estimates for the US attributable fraction are limited to a few observational studies. To describe the burden of infection-associated cancer in the United States, additional observational studies are necessary to estimate the prevalence of infection nationally and within subpopulations. As infectious associations emerge to explain cancer etiologies, new opportunities and challenges to reducing the burden arise. Improved estimates for the United States would help target interventions to higher-risk subpopulations.

Development of anti-human CADM1 monoclonal antibodies as a potential therapy for adult T-cell leukemia/lymphoma

Adult T-cell leukemia/lymphoma (ATLL) is a highly invasive and refractory T-cell malignancy, with poor prognosis. We previously identified that cell adhesion molecule 1 (CADM1) is overexpressed consistently in ATLL cells, and that CADM1 expression increases the adhesion capacity of ATLL cells to endothelial cells and promotes the organ invasion of ATLL cells in a xenograft mouse model. In this study, we first show that newly developed several anti-human CADM1 antibodies, which were complete human IgG antibodies generated by phage display method, specifically recognize CADM1 on ATLL cells. Although most of the CADM1 antibodies did not have a direct cytotoxic effect against CADM1-positive ATLL cells, clone 089-084 exhibited weak but significant antibody-dependent cell-mediated cytotoxic activity. Moreover, clone 103-189 effectively inhibits the interaction between endothelial cells and CADM1-positive ATLL cells. Furthermore, in mice bearing intra-splenic transplantation of EL4 mouse lymphoma cells expressing CADM1, the treatment of 103-189 significantly suppressed the organ invasion of CADM1-positive EL4 cells, resulting in improved survival time of mice. Therefore, since the anti-CADM1 antibody may be useful for the suppression of organ invasion in ATLL patients, combination use of the anti-CADM1 antibody with chemotherapy drugs could be beneficial for the efficient elimination of ATLL cells.

Mechanisms of Oncogenesis by HTLV-1 Tax

The human T-cell lymphotropic virus type 1 (HTLV-1) is the etiological agent of adult T-cell leukemia/lymphoma (ATLL), a neoplasm of CD4+CD25+ T cells that occurs in 2-5% of infected individuals after decades of asymptomatic latent infection. Multiple HTLV-1-encoded regulatory proteins, including Tax and HTLV-1 basic leucine zipper factor (HBZ), play key roles in viral persistence and latency. The HTLV-1 Tax oncoprotein interacts with a plethora of host cellular proteins to regulate viral gene expression and also promote the aberrant activation of signaling pathways such as NF-κB to drive clonal proliferation and survival of T cells bearing the HTLV-1 provirus. Tax undergoes various post-translational modifications such as phosphorylation and ubiquitination that regulate its function and subcellular localization. Tax shuttles in different subcellular compartments for the activation of anti-apoptotic genes and deregulates the cell cycle with the induction of DNA damage for the accumulation of genomic instability that can result in cellular immortalization and malignant transformation. However, Tax is highly immunogenic and therefore HTLV-1 has evolved numerous strategies to tightly regulate Tax expression while maintaining the pool of anti-apoptotic genes through HBZ. In this review, we summarize the key findings on the oncogenic mechanisms used by Tax that set the stage for the development of ATLL, and the strategies used by HTLV-1 to tightly regulate Tax expression for immune evasion and viral persistence.

Synthetic (E)-3-Phenyl-5-(phenylamino)-2-styryl-1,3,4-thiadiazol-3-ium Chloride Derivatives as Promising Chemotherapy Agents on Cell Lines Infected with HTLV-1

Synthesis of four compounds belonging to mesoionic class, (E)-3-phenyl-5-(phenylamino)-2-styryl-1,3,4-thiadiazol-3-ium chloride derivatives (5a–d) and their biological evaluation against MT2 and C92 cell lines infected with human T-cell lymphotropic virus type-1 (HTLV-1), which causes adult T-cell leukemia/lymphoma (ATLL), and non-infected cell lines (Jurkat) are reported. The compounds were obtained by convergent synthesis under microwave irradiation and the cytotoxicity was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. Results showed IC₅₀ values of all compounds in the range of 1.51–7.70 μM in HTLV-1-infected and non-infected cells. Furthermore, it was observed that 5b could induce necrosis after 24 h for Jurkat and MT2 cell lines. The experimental (fluorimetric method) and theoretical (molecular docking) results suggested that the mechanism of action for 5b could be related to its capacity to intercalate into DNA. Moreover, the preliminary pharmacokinetic profile of the studied compounds (5a–d) was obtained through human serum albumin (HSA) binding affinity using multiple spectroscopic techniques (circular dichroism, steady-state and time-resolved fluorescence), zeta potential and molecular docking calculations. The interaction HSA:5a–d is spontaneous and moderate (K_a ~ 10⁴ M⁻¹) via a ground-state association, without significantly perturbing both the secondary and surface structures of the albumin in the subdomain IIA (site I), indicating feasible biodistribution in the human bloodstream.

Novel Treatments of Adult T Cell Leukemia Lymphoma

Adult T cell leukemia-lymphoma (ATL) is an aggressive malignancy secondary to chronic infection with the human T cell leukemia virus type I (HTLV-I) retrovirus. ATL carries a dismal prognosis. ATL classifies into four subtypes (acute, lymphoma, chronic, and smoldering) which display different clinical features, prognosis and response to therapy, hence requiring different clinical management. Smoldering and chronic subtypes respond well to antiretroviral therapy using the combination of zidovudine (AZT) and interferon-alpha (IFN) with a significant prolongation of survival. Conversely, the watch and wait strategy or chemotherapy for these indolent subtypes allies with a poor long-term outcome. Acute ATL is associated with chemo-resistance and dismal prognosis. Lymphoma subtypes respond better to intensive chemotherapy but survival remains poor. Allogeneic hematopoietic stem cell transplantation (HSCT) results in long-term survival in roughly one third of transplanted patients but only a small percentage of patients can make it to transplant. Overall, current treatments of aggressive ATL are not satisfactory. Prognosis of refractory or relapsed patients is dismal with some encouraging results when using lenalidomide or mogamulizumab. To overcome resistance and prevent relapse, preclinical or pilot clinical studies using targeted therapies such as arsenic/IFN, monoclonal antibodies, epigenetic therapies are promising but warrant further clinical investigation. Anti-ATL vaccines including Tax peptide-pulsed dendritic cells, induced Tax-specific CTL responses in ATL patients. Finally, based on the progress in understanding the pathophysiology of ATL, and the risk-adapted treatment approaches to different ATL subtypes, treatment strategies of ATL should take into account the host immune responses and the host microenvironment including HTLV-1 infected non-malignant cells. Herein, we will provide a summary of novel treatments of ATL in vitro, in vivo, and in early clinical trials.

Human T-Cell Lymphotropic Virus Type 1 Transactivator Tax Exploits the XPB Subunit of TFIIH during Viral Transcription

Human T-cell lymphotropic virus type 1 (HTLV-1) Tax oncoprotein is required for viral gene expression. Tax transactivates the viral promoter by recruiting specific transcription factors but also by interfering with general transcription factors involved in the preinitiation step, such as TFIIA and TFIID. However, data are lacking regarding Tax interplay with TFIIH, which intervenes during the last step of preinitiation. We previously reported that XPB, the TFIIH subunit responsible for promoter opening and promoter escape, is required for Tat-induced human-immunodeficiency virus promoter transactivation. Here, we investigated whether XPB may also play a role in HTLV-1 transcription. We report that Tax and XPB directly interact in vitro and that endogenous XPB produced by HTLV-1-infected T cells binds to Tax and is recruited on proviral LTRs. In contrast, XPB recruitment at the LTR is not detected in Tax-negative HTLV-1-infected T cells and is strongly reduced when Tax-induced HTLV-1 LTR transactivation is blocked. XPB overexpression does not affect basal HTLV-1 promoter activation but enhances Tax-mediated transactivation in T cells. Conversely, downregulating XPB strongly reduces Tax-mediated transactivation. Importantly, spironolactone (SP)-mediated inhibition of LTR activation can be rescued by overexpressing XPB but not XPD, another TFIIH subunit. Furthermore, an XPB mutant defective for the ATPase activity responsible for promoter opening does not show rescue of the effect of SP. Finally, XPB downregulation reduces viability of Tax-positive but not Tax-negative HTLV-1-transformed T cell lines. These findings reveal that XPB is a novel cellular cofactor hijacked by Tax to facilitate HTLV-1 transcription.IMPORTANCE HTLV-1 is considered the most potent human oncovirus and is also responsible for severe inflammatory disorders. HTLV-1 transcription is undertaken by RNA polymerase II and is controlled by the viral oncoprotein Tax. Tax transactivates the viral promoter first via the recruitment of CREB and its cofactors to the long terminal repeat (LTR). However, how Tax controls subsequent steps of the transcription process remains unclear. In this study, we explore the link between Tax and the XPB subunit of TFIIH that governs, via its ATPase activity, the promoter-opening step of transcription. We demonstrate that XPB is a novel physical and functional partner of Tax, recruited on HTLV-1 LTR, and required for viral transcription. These findings extend the mechanism of Tax transactivation to the recruitment of TFIIH and reinforce the link between XPB and transactivator-induced viral transcription.

Inhibition of IκBα phosphorylation potentiates regulated cell death induced by azidothymidine in HTLV-1 infected cells

Adult T cell leukemia/lymphoma (ATL) can be susceptible, at least transiently, to treatments with azidothymidine (AZT) plus IFNα and/or arsenic trioxide. However, the real role of AZT in this effect is still unclear. In fact, while reverse transcriptase (RT) inhibition could explain reduction of clonal expansion and of renewal of HTLV-1 infected cells during ATL progression, this effect alone seems insufficient to justify the evident and prompt decrease of the pro-viral load in treated patients. We have previously demonstrated that AZT is endowed with an intrinsic pro-apoptotic potential towards both peripheral blood mononuclear cells from healthy donors or some tumor cell lines, but this cytotoxic potential cannot be fully achieved unless IκBα phosphorylation is inhibited. Since the constitutive activation of NF-kappa B (NF-κB) appears a common biological basis of HTLV-1-infected cells, a pharmacological inhibition of IκBα phosphorylation seems a potential strategy for treating and preventing HTLV-1 related pathologies. In this study, we have demonstrated that a combination treatment with the IκBα phosphorylation inhibitor Bay 11-7085 and AZT induced increased levels of regulated cell death (RCD) by apoptosis compared to the single treatments in HTLV-1 infected cells of different origin. Importantly, levels of RCD were considerably higher in infected cells in comparison with the uninfected ones. Inhibition of NF-κB activation following the combined treatment was confirmed by analysis of both gel-shift and functional activity of the NF-κB complex proteins, p65/p52. Moreover, a transcriptional analysis revealed that the addition of Bay 11-7085 to AZT treatment in HTLV-1-infected cells modified their transcriptional profile, by inducing the upregulation of some pro-apoptotic genes together with the downregulation of some anti-apoptotic genes. Our data suggest that addition of adequate concentrations of IκBα phosphorylation inhibitor to therapeutic regimens including AZT could be a promising strategy in ATL.

Targeting histone epigenetics to control viral infections

During the past decades, many studies have significantly broadened our understanding of complex virus-host interactions to control chromatin structure and dynamics.1, 2 However, the role and impact of such modifications during viral infections is not fully revealed. Indeed, this type of regulation is bidirectional between the virus and the host. While viral replication and gene expression are significantly impacted by histone modifications on the viral chromatin,³ studies have shown that some viral pathogens dynamically manipulate cellular epigenetic factors to enhance their own survival and pathogenesis, as well as escape the immune system defense lines.⁴ In this dynamic, histone posttranslational modifications (PTMs) appear to play fundamental roles in the regulation of chromatin structure and recruitment of other factors.⁵ Genuinely, those PTMs play a vital role in lytic infection, latency reinforcement, or, conversely, viral reactivation.⁶ In this chapter, we will examine and review the involvement of histone modifications as well as their potential manipulation to control infections during various viral life cycle stages, highlighting their prospective implications in the clinical management of human immunodeficiency virus (HIV), herpes simplex virus (HSV), human cytomegalovirus (HCMV), hepatitis B and C viruses (HBV and HCV, respectively), Epstein–Barr virus (EBV), and other viral diseases. Targeting histone modifications is critical in setting the treatment of chronic viral infections with both lytic and latent stages (HIV, HCMV, HSV, RSV), virus-induced cancers (HBV, HCV, EBV, KSHV, HPV), and epidemic/emerging viruses (e.g. influenza virus, arboviruses).

Mechanistic Insights into Chemoresistance Mediated by Oncogenic Viruses in Lymphomas

Viral lymphomagenesis induced by infection with oncogenic viruses, such as Kaposi’s sarcoma associated herpesvirus (KSHV), Epstein–Barr virus (EBV) and human T-cell leukemia virus (HTLV-1), represents a group of aggressive malignancies with a diverse range of pathological features. Combined chemotherapy remains the standard of care for these virus-associated lymphomas; however, frequent chemoresistance is a barrier to achieving successful long-term disease-free survival. There is increasing evidence that indicates virus-associated lymphomas display more resistance to cytotoxic chemotherapeutic agents than that observed in solid tumors. Although the tumor microenvironment and genetic changes, such as key oncogene mutations, are closely related to chemoresistance, some studies demonstrate that the components of oncogenic viruses themselves play pivotal roles in the multidrug chemoresistance of lymphoma cells. In this review, we summarize recent advances in the understanding of the mechanisms through which oncogenic viruses mediate lymphoma cell chemoresistance, with a particular focus on KSHV and EBV, two major oncogenic viruses. We also discuss the current challenges to overcome these obstacles in the treatment of virus-associated lymphomas.

NF-κB and MicroRNA Deregulation Mediated by HTLV-1 Tax and HBZ

The risk of developing adult T-cell leukemia/lymphoma (ATLL) in individuals infected with human T-cell lymphotropic virus 1 (HTLV-1) is about 3-5%. The mechanisms by which the virus triggers this aggressive cancer are still an area of intensive investigation. The viral protein Tax-1, together with additional regulatory proteins, in particular HTLV-1 basic leucine zipper factor (HBZ), are recognized as relevant viral factors required for both viral replication and transformation of infected cells. Tax-1 deregulates several cellular pathways affecting the cell cycle, survival, and proliferation. The effects of Tax-1 on the NF-κB pathway have been thoroughly studied. Recent studies also revealed the impact of Tax-1 and HBZ on microRNA expression. In this review, we summarize the recent progress in understanding the contribution of HTLV-1 Tax- and HBZ-mediated deregulation of NF-κB and the microRNA regulatory network to HTLV-1 pathogenesis.

High expression of NAMPT in adult T-cell leukemia/lymphoma and anti-tumor activity of a NAMPT inhibitor

Adult T-cell leukemia/lymphoma (ATL) is a malignancy of mature T lymphocytes induced by human T-cell leukemia virus-1 and has a poor outcome. New molecular targets for the prevention and treatment of ATL are needed urgently. We previously reported high expression of Sirtuin 1, a nicotinamide adenine dinucleotide (NAD⁺)-dependent histone/protein deacetylase, in primary acute-type ATL cells. NAD⁺ biosynthesis via nicotinamide phosphoribosyltransferase (NAMPT) modulates Sirtuin 1 activity. Here, we examined the expression and effects of inhibiting NAMPT, a rate-limiting enzyme in NAD⁺ biosynthesis, in ATL cells. We found that peripheral blood mononuclear cells from patients with acute-type ATL expressed significantly higher levels of NAMPT protein than cells from healthy subjects. FK866, a NAMPT inhibitor, induced apoptosis of freshly isolated ATL cells ex vivo and HTLV-1-infected T-cell lines in vitro, which was accompanied by activation of caspases, DNA fragmentation, and disruption of mitochondrial transmembrane potential. However, a pan-caspase inhibitor failed to prevent this FK866-induced cell death, while FK866 increased the caspase-independent cell death mediator endonuclease G. Intriguingly, FK866 also activated autophagy, as demonstrated by increases in protein levels of autophagosome marker LC3-II. Thus, FK866 simultaneously activated apoptosis and autophagy. Finally, FK866 treatment markedly decreased the growth of human ATL tumor xenografts in immunodeficient mice. We showed that NAMPT is highly expressed in primary ATL cells ex vivo, and that FK866 induces autophagy and caspase-dependent and -independent cell death pathways in vitro and has an anti-tumor activity in vivo. These results suggest a novel therapeutic strategy for patients with this fatal disease.