Adult T-cell leukemia: a review of epidemiological evidence

Trends of changes in human T-cell leukemia virus type 1 epidemiology in Japan and globally

Human T-cell leukemia virus type 1 (HTLV-1) has been identified as a cause of adult T-cell leukemia-lymphoma (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Despite several HTLV-1 endemic areas being identified, comprehensive investigations have yet to be conducted in all the regions of the world. This review aims to summarize the current reports on HTLV-1. As vertical transmission is known to be a risk factor for ATL development, prevention strategies have been initiated in Japan, and these efforts may be related to the decrease in the estimated number of HTLV-1 carriers in Japan. In numerous HTLV-1 endemic regions, the prevalence of HTLV-1 increases with age, which may be attributed to horizontal infection. However, the incidence of HTLV-1 infection appears to be high among adolescents and young adults in Japan, especially in non-endemic areas. The clinical significance of HTLV-1 infections, other than ATL and HAM/TSP, has recently been documented. Consequently, it is imperative to develop treatment strategies for HTLV-1 infections, including measures to prevent horizontal infections.

Long-term kinetics of proviral load in HTLV-1 carriers: defining risk for the development of adult T-cell leukemia/lymphoma

BACKGROUND

Assessment of adult T-cell leukemia/lymphoma (ATL) development among human T-lymphotropic virus 1 (HTLV-1)-infected individuals (carriers) constitute a significant issue. A high HTLV-1 proviral load (PVL) in carriers has been used as a risk factor for ATL development and PVLs are considered to remain unchanged over time among carriers.

METHODS

This single-center analysis used a cohort from a prospective observational study of HTLV-1 carriers in Japan (JSPFAD). Carriers whose PVL was measured at least twice between October 2004 and March 2023 were included. We used trajectory analysis to construct a kinetic model of the PVL.

RESULTS

Analysis of 1371 samples from 252 carriers revealed a slight but significant increase in the PVL with age (P < 0.001). Trajectory analysis of PVL kinetics classified the carriers into six groups, in three of which increased over time. When we applied the model to 15 carriers who subsequently developed ATL, 12 (80%) were classified into the highest PVL group, with an estimated 15-year ATL development of 47.5% (95% confidence interval: 20.4-74.2%). Notably, younger patients are at greater risk of developing ATL if their PVL values are comparable. Our risk estimation model is available online ( https://atlriskpredictor.shinyapps.io/ATL_risk_calculator/ ).

CONCLUSIONS

This study demonstrated that the PVLs increases over time, allowing for prospective risk estimation for ATL development. Further validation is needed to assess the validity of this model.

TRIAL REGISTRATION

Retrospectively registered.

The role of human leukocyte antigen in HTLV-1 infection and progression to ATLL and HAM/TSP: a systematic review and meta-analysis

BACKGROUND

Human T-cell lymphotropic virus type 1 (HTLV-1) is a retrovirus that leads to lifelong infection and multiple diseases, including HAM/TSP and ATLL. Despite extensive research, the exact pathophysiology of HTLV infection and its related diseases is enigmatic. In this study, we aimed to review and analyze the effect of different HLA alleles as protective or predisposing factors in HTLV-1 infection and its progression to related diseases.

METHOD

Three databases (PubMed, Web of Science, and Scopus) were searched for eligible studies. Twenty-five papers with 7279 participants were included in the quantitative analysis. The relevant data were extracted, and 198 meta-analyses were conducted on each reported HLA and population.

RESULTS

The results of our investigation suggest 3 HLAs with preventive effects against HTLV infection, including HLA-B*35, DRB1*09, and DRB1*16. Also, HLA-DQB1*05:01 might prevent HTLV progression to ATLL. In contrast, HLA-DRB1*13 is more prevalent in ATLL patients than HTLV carriers. Additionally, our results propound that carriers of HLA-A*28, B*54, C*07, DQB1*03:01, and DRB1*07:01 are at higher risk, and carriers of HLA-A*30, B*37, B*40, B*44, C*08, DQB1*06:02, and DRB1*15:01 are in lower risk of HTLV progression to HAM/TSP. We concluded that the mentioned HLA alleles are potential biomarkers of HTLV infection and its progression to related diseases.

Recent progress in pathological understanding of adult T-cell leukemia/lymphoma in the new classification era

Adult T-cell leukemia/lymphoma (ATLL) is a peripheral T-cell lymphoma caused by Human T-cell leukemia virus type 1 (HTLV-1) infection. Although the 5th Edition of the WHO classification (WHO-5) did not make drastic changes regarding the disease concept of ATLL from the revised 4th Edition of the WHO classification (WHO-4R), WHO-5 newly introduced the essential and desirable diagnostic criteria, namely, "neoplastic lymphoid cell proliferation with mature T-cell phenotype; proven HTLV-1 carriership" and "identification of monoclonal integration of HTLV-1", respectively. To satisfy the desirable criteria, a new diagnostic method using a combination of HBZ-ISH and tax-PCR was introduced for the identification of the HTLV-1 in addition to the conventionally used Southern blot hybridization, especially in the case when only FFPE specimens are available. Morphologically, pleomorphic- and anaplastic large cell-type, account for most cases, while minor variants, ATLL with dermatopathic reaction, angioimmunoblastic T-cell lymphoma-like variant, and classic Hodgkin lymphoma-like variant, should also be noted as diagnostic pitfalls. Phenotypically, about 80 % of ATLL cases show a typical phenotype of CD3 + CD4 +CD25 +CCR4 + , while about 10 % show atypical phenotypes such as T follicular helper cell-like one. Many genetic abnormalities, mainly associated with the TCR signaling pathway, are observed, and most are more frequent in the aggressive type than in the indolent type, except for STAT3, indicating the heterogeneous pathogenic process of ATLL. In this review, we present the latest findings on molecular pathogenesis and histopathological findings of ATLL in the era of the new classification of lymphomas, serving as a basis for future research and classification.

Immunological aspects of HTLV-1 persistence; for the prevention and treatment of Adult T-cell leukaemia-lymphoma (ATL)

Human T-cell leukaemia virus type-1 (HTLV-1) causes the highly aggressive malignancy adult T-cell leukaemia-lymphoma (ATL) in approximately 5 % of chronically infected carriers. HTLV-1 persists in the host by enhancing survival of infected-T-cells despite the presence of a strong immune response. Therefore, asymptomatic HTLV-1 carriers have a lifelong balance between infected cell proliferation and the host antiviral immune response. However, this immunological balance is lost in patients with ATL. Reliable treatment options are lacking and there is urgent need for new treatment strategies to improve the dismal prognosis of ATL. In this review, we present a summary of the current knowledge on the immunological aspects of HTLV-1 persistence and the immune alterations observed in ATL, and discuss how the recent emerging advances in adoptive immunotherapy may offer a prevention and treatment option for ATL.

Evaluation of ALKBH2 and ALKBH3 gene regulation in patients with adult T-cell leukemia/lymphoma

BACKGROUND

Human T-cell leukemia virus type 1 (HTLV-1) is an oncogenic virus that causes malignant adult T-cell leukemia/lymphoma (ATL). Patients infected with HTLV-1 are considered HTLV-1 carriers, and a small proportion of patients progress to life-threatening ATL after a long asymptomatic phase. No antiviral agent or preventive vaccine specific for HTLV-1 infection is established in current situation. For development of countermeasures to combat HTLV-1 infection and ATL, it is essential to expand our knowledge about their pathogenesis. Recently, AlkB homolog (ALKBH) family have been shown to participate in the oncogenesis of various cancer types.

METHODS

To investigate the potential role of ALKBH family members in the pathogenesis of ATL, we analyzed their gene expression dynamics in HTLV-1-infected T-cell lines and peripheral blood mononuclear cell-derived clinical specimens obtained from asymptomatic HTLV-1 carriers and patients with acute-type ATL. Epigenetic analysis was performed to dissect the mechanisms of ALKBH3 gene regulation using cultivated cells and a public dataset.

RESULTS

The mRNA expression levels of ALKBH2 and ALKBH3 were significantly or suggestively decreased in asymptomatic HTLV-1 carriers, but reverted in acute-type ATL patients, correlating with HTLV-1 basic leucine zipper factor gene expression. Intriguingly, the pre-mRNA expression of ALKBH2 and ALKBH3 was significantly suppressed in patients infected with HTLV-1, but not in healthy controls. Epigenetic analysis was performed to dissect the mechanisms of ALKBH3 gene regulation. In vitro analysis suggested a possible relationship between DNA methylation and ALKBH3 gene expression. Investigation of a public dataset revealed that specific CpG sites exhibited characteristically regulated methylation states in HTLV-1-infected T-cell subsets.

CONCLUSION

We discovered dynamically regulated patterns of ALKBH2 and ALKBH3 gene expression in patients infected with HTLV-1, and specific CpG sites epigenetically regulated by HTLV-1 infection. This study provides novel insights into HTLV-1 infection and contributes to the elucidation of ATL pathogenesis.

Epstein Barr virus: A cellular hijacker in cancer

Numerous studies have demonstrated the importance of the Epstein-Barr Virus (EBV), which was initially identified in 1964 while studying Burkitt's lymphoma, in the development of a number of cancers, including nasopharyngeal carcinoma, Hodgkin's lymphoma, Burkitt's lymphoma, and EBV-associated gastric carcinoma. Gammaherpesvirus EBV is extremely common; by adulthood, over 90 % of people worldwide have been infected. Usually, the virus causes a permanent latent infection in B cells, epithelial cells, and NK/T cells. It then contributes to oncogenesis by inhibiting apoptosis and promoting unchecked cell proliferation through its latent proteins, which include EBNA-1, LMP1, and LMP2A. Tumor progression further accelerated by EBV's capacity to transition between latent and lytic phases, especially in cases of nasopharyngeal carcinoma. Although our understanding of the molecular underpinnings of EBV has advanced, there are still difficulties in identifying latent infections and creating targeted therapeutics. To tackle EBV-associated malignancies, current research efforts are concentrated on developing vaccines, developing better diagnostic tools, and developing targeted treatments. In order to improve treatment approaches and lower the incidence of EBV-related cancers worldwide, more research into the relationship between EBV and immune evasion and cancer formation is necessary.

Antiviral immune response against HTLV-1 invalidates T-SPOT.TB® results in patients with HTLV-1-positive rheumatic diseases

Background

T-SPOT.TB®, one of the screening tests for latent tuberculosis infection (LTBI), yields invalid results in human T-cell leukemia virus type 1 (HTLV-1)-positive patients with rheumatoid arthritis. However, the detailed mechanisms behind this invalidation are unclear. Additionally, it remains unclear whether T-SPOT.TB® or QuantiFERON-TB (QFT) is more useful in HTLV-1-positive patients with rheumatic disease (RD).

Method

Among all of the HTLV-1-positive RD patients who visited our department between August 2012 and December 2022, 44 patients who were screened using T-SPOT.TB® were included in the analysis. QFT testing was performed in 33 of the 44 patients, and the results were compared with that of T-SPOT.TB®. Furthermore, we performed a culture experiment mimicking T-SPOT.TB® using peripheral blood mononuclear cells (PBMCs) obtained from HTLV-1-positive patients with RD. Additionally, T-cell subsets with autonomous product IFN-γ were analyzed using a flow cytometer.

Results

Of the included patients, 13 (29.5%) were invalid for T-SPOT.TB® because of the increased number of negative control spots. The median HTLV-1 proviral load in the invalid group was higher than that in the valid group (2.45 vs. 0.49 copies/100 PBMCs, respectively, p = 0.002). QFT was performed in all 33 patients, including 13 patients who were invalid in T-SPOT.TB®. The main source of IFN-γ production was CD8+ T-cells in the T-SPOT.TB® mimic experiment. Furthermore, Tax-expressing CD4+ T-cells and Tax-specific cytotoxic CD8+ T-cells were more frequently observed in patients with invalid results than in patients with valid results. CD4+ T-cell depletion in the T-SPOT.TB® mimic experiment reduced the population of IFN-γ producing CD8+ T cells.

Conclusion

T-SPOT.TB® may be invalidated by the interaction between Tax-expressing CD4+ T-cells and cytotoxic CD8+ T-cells. Moreover, HTLV-1-associated immune reactions due to contact between these cells may be unlikely to occur in QFT using whole blood. Therefore, our results reveal the superiority of QFT over T-SPOT.TB® as a screening test for LTBI in HTLV-1-positive patients with RD.

The role and impact of viruses on cancer development

This review focuses on three major aspects of oncoviruses' role in cancer development. To begin, we discuss their geographic distribution, revealing that seven oncoviruses cause 20% of all human cancers worldwide. Second, we investigate the primary carcinogenic mechanisms, looking at how these oncogenic viruses can induce cellular transformation, angiogenesis, and local and systemic inflammation. Finally, we investigate the possibility of SARS-CoV-2 infection reactivating latent oncoviruses, which could increase the risk of further disease. The development of oncovirus vaccines holds great promise for reducing cancer burden. Many unanswered questions about the host and environmental cofactors that contribute to cancer development and prevention remain, which ongoing research is attempting to address.

Cytotoxicity of bendamustine, alone and in combination with novel agents, toward adult T-cell leukemia cells

Adult T-cell leukemia/lymphoma (ATL) develops from the infection of T cells with human T lymphotropic virus type 1 (HTLV-1). There are an estimated 5-20 million HTLV-1 carriers worldwide and the patients are frequently observed in subtropical Africa, the Caribbean, Middle East, South America, and South West Japan. The prognosis of ATL remains dismal due to rapid acquired resistance to treatment with cytotoxic chemotherapeutic agents. In particular, the development of novel therapies for relapsed or refractory (R/R) ATL is an unmet need. Previous clinical trials revealed that bendamustine (BDM) was effective as the first-line treatment for indolent lymphoma and R/R cases of diffuse large B-cell lymphoma. Its major advantage is that it has few side effects such as hair loss and peripheral neuropathy, and does not impair the quality of life. However, its efficacy has not been verified for ATL in pre-clinical or clinical studies. In this study, we have shown the cytotoxicity of BDM alone and in combination with novel agents including the histone deacetylase (HDAC) inhibitor tucidinostat, the enhancer of zeste homolog 1/2 (EZH1/2) dual inhibitor valemetostat, and the Bcl2 family inhibitor ABT-737. The combined in vitro effects of BDM and tucidinostat were reproduced in a murine model without any obvious hematological toxicity. Our present results suggest that the combination of tucidinostat and BDM could additively prolong the survival of patients with R/R progressive ATL. The efficacy and safety of this combination are thus worthy of investigation in clinical settings.

Human T-cell lymphotropic virus screening in France: Missed opportunities? A retrospective multicenter study of serological testing in hospital laboratories

Objectives

Human T-lymphotropic virus 1 infection is endemic in the French Antilles, French Guiana, and sub-Saharan Africa, the origin of many immigrants currently living in France. There are no national screening recommendations outside of the regulatory obligations concerning donations of blood, tissue, gametes, or milk to a lactarium. This study aimed to investigate the screening and diagnostic practices for this infection in France.

Methods

Serological statistics for regulatory, antenatal, sexually transmitted infections (for CeGIDDs (Centre Gratuit d'Information, de Dépistage et de Diagnostic des Infections Sexuellement Transmissibles), which are public sexual health clinics), accidental exposure to blood screenings, and diagnosis since January 1, 2018 were collected from 23 hospital laboratories (two in the French Antilles, 21 in mainland France) associated with 55 hospitals and 22 maternity units.

Results

A total absence of antenatal screening was reported by 75% of the laboratories associated with maternity units in mainland France. All the laboratories in mainland France reported an absence of screening in the accidental exposure to blood context, as did all the laboratories in mainland France associated with a CeGIDD in the context of sexually transmitted infection screening. Conversely, screening in accordance with the existing regulations was generally systematically carried out. The most frequently reported diagnostic contexts were hematology and neurology.

Conclusions

This study reveals an underscreening of human T-lymphotropic virus 1 in the hospital laboratories of mainland France.

Flow cytometric profiles with CD7 and CADM1 in CD4+ T cells are promising indicators for prognosis of aggressive ATL

ABSTRACT

Adult T-cell leukemia/lymphoma (ATL) is a poor prognosis hematological malignancy originating from human T-cell leukemia virus 1 (HTLV-1)-infected CD4+ T cells. Flow cytometric plots of CADM1 and CD7 in CD4+ T cells are useful for separating HTLV-1-uninfected T cells and ATL cells. They are indicators of clonal evolution of HTLV-1-infected cells and disease progression of asymptomatic carriers or indolent ATL. However, the impacts of the plots on the clinical course or prognosis of ATL, especially in aggressive ATL, remain unclear. We focused on the N fraction (CD4+ CADM1+ CD7-) reflecting ATL cells and analyzed the flow cytometric profiles and clinical course of 497 samples from 92 HTLV-1-infected patients who were mainly aggressive ATL. The parameters based on N fractions showed significant correlations with known indicators of ATL disease status (soluble interleukin-2 receptor, lactate dehydrogenase, abnormal lymphocytes, etc.) and sensitively reflected the treatment response of aggressive ATL. The parameters based on N fractions significantly stratified the prognosis of aggressive ATL at 4 different time points: before treatment, after 1 course of chemotherapy, at the best response after chemotherapy, and before allogeneic hematopoietic cell transplantation. Even after mogamulizumab administration, which shows potent effects for peripheral blood lesions, the N fraction was still a useful indicator for prognostic estimation. In summary, this report shows that CADM1 vs CD7 plots in CD4+ T cells are useful indicators of the clinical course and prognosis of aggressive ATL. Therefore, this CADM1 and CD7 profile is suggested to be a useful prognostic indicator consistently from HTLV-1 carriers to aggressive ATL.

The Interactions between Cells and Viruses

Many infectious diseases are caused by life-threatening DNA and RNA viruses and have been reported worldwide, including those caused by emerging and re-emerging viruses [...].

Update on T-Cell Lymphoma Epidemiology

PURPOSE OF REVIEW

T-cell lymphomas (TCLs) are a group of rare subtypes of non-Hodgkin lymphoma derived from mature T-lymphocytes. Recent updates in lymphoma classification based on the cell-of-origin pathogenesis have shed new light on TCL epidemiology and outcomes. Contemporary regional consortia and international studies, including those conducted recently in Asia and South America, have provided an updated delineation of the major subtypes across various global regions.

RECENT FINDINGS

Peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS), remains the most common subtype globally except in Asia, where extra-nodal NK-T cell lymphoma (ENKTL) has emerged as the most prevalent. Angioimmunoblastic T-cell lymphoma (AITL) is the second most common subtype globally except in South America where its incidence falls behind adult T-cell leukemia/lymphoma (ATLL) and ENKTL. ALK-negative anaplastic large cell lymphoma (ALCL) has been recognized as the second most common subtype in some parts of South America. Studies on the newly classified breast implant-associated ALCL (BIA-ALCL) are beginning to reveal its distribution and risk factors. Deciphering the epidemiology of TCLs is a challenging endeavor due to the rarity of these entities and ongoing refinement in classification. Collaborative efforts on prospective registries based on the most current WHO classifications will help capture the true epidemiology of TCL subtypes to better focus resources for diagnostic, prognostic, and therapeutic efforts.

Clinical Features and Survival Outcome in Aggressive-Type Adult T-Cell Leukemia/Lymphoma Patients: Real-Life Experience of a Single Center from an HTLV-1 Endemic Country

Background and Objectives: Adult T-cell leukemia/lymphoma (ATLL) is a highly aggressive T-cell lymphoproliferative disease associated with the human T-cell lymphotropic virus type I (HTLV-1). ATLL is a rare disease, found more frequently in HTLV-1-endemic areas, Romania being one of them. Despite treatment advances, the prognosis remains dismal. We aimed to describe the clinical, biological, and survival outcome features of Romanian patients with aggressive-type ATLL. Materials and Methods: We report the data of a prospective, observational, and unicentric study of all 20 patients diagnosed with lymphoma and acute types of ATLL at our center over the past 12 years. Data were collected from the patients' medical records. Results: Lymphoma-type ATLL (60%) was more common than acute-type ATLL (40%). Median age at diagnosis was 40.5 years, and most patients were female. Laboratory data revealed significant differences between acute and lymphoma-type ATLL, namely, higher leukocyte (p = 0.02) and lymphocyte counts (p = 0.02) and higher levels of corrected calcium (p = 0.001) in acute-type ATLL. All patients received chemotherapy, and only two underwent allogeneic stem cell transplantation. Only six patients obtained a complete or partial response to chemotherapy, mostly the lymphoma-type ones. The median survival for all patients was 6.37 months, with higher survival in the lymphoma-type ATLL (8.16 months) than in the acute-type (3.60 months). Normal calcium levels (p = 0.011), uric acid (p = 0.005), BUN score (p = 0.000), JCOG-PI moderate risk (p = 0.038), and obtaining complete or partial response (p = 0.037) were associated with higher survival. Conclusion: Aggressive-type ATLL among Romanian patients presents distinct characteristics, including younger age at diagnosis, female predominance, and higher incidence of lymphoma-type ATLL compared to currently reported data. Survival remains very low, with all subtypes experiencing a median survival of less than one year.

Non-cancerous complications in HTLV-1 carriers

INTRODUCTION

Human T-cell leukemia virus type 1 (HTLV-1) carriers may develop adult T-cell leukemia (ATL), or HTLV-1-associated myelopathy (HAM)/tropical spastic paraparesis (TSP). The evidence is limited regarding other diseases potentially associated with HTLV-1, such as HTLV-1-associated autoimmune diseases.

AREA COVERED

We summarized the available information on complications associated with HTLV-1 infection.

EXPERT OPINION

Previous studies showed that HTLV-1 carriers have an increased incidence of collagen diseases including Sjögren's syndrome, as well as dysthyroidism, diabetes mellitus, and atherosclerosis. Furthermore, cognitive deficits are observed in asymptomatic carriers and in symptomatic carriers who develop HAM/TSP. It is hypothesized that altered immunoregulation occurs as a result of persistent HTLV-1 infection. A systematic review and meta-analysis demonstrated that HTLV-1 infection itself has an adverse impact on overall survival. ATL alone cannot entirely explain the adverse impact of HTLV-1 infection on overall mortality, because the incidence is low, and therefore HTLV-1-associated diseases as a whole may contribute to the inferior clinical outcome. However, there are insufficient data to determine the causal relationship between HTLV-1 infection and each complication. While non-cancerous events linked to HTLV-1 infection are not fatal, they are likely to reduce quality of life. Large prospective studies should be conducted by international collaborators.

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.

PCBP1 interacts with the HTLV-1 Tax oncoprotein to potentiate NF-κB activation

Human T-cell leukemia virus type 1 (HTLV-1) is the etiological agent of adult T-cell leukemia/lymphoma. The HTLV-1 Tax constitutively activates nuclear factor-κB (NF-κB) to promote the survival and transformation of HTLV-1-infected T cells. Despite extensive study of Tax, how Tax interacts with host factors to regulate NF-κB activation and HTLV-1-driven cell proliferation is not entirely clear. Here, we showed that overexpression of Poly (rC)-binding protein 1 (PCBP1) promoted Tax-mediated IκB kinase (IKK)-NF-κB signaling activation, whereas knockdown of PCBP1 attenuated Tax-dependent IKK-NF-κB activation. However, Tax activation of HTLV-1 long terminal repeat was unaffected by PCBP1. Furthermore, depletion of PCBP1 led to apoptosis and reduced proliferation of HTLV-1-transformed cells. Mechanistically, PCBP1 interacted and co-localized with Tax in the cytoplasm, and PCBP1 KH3 domain was indispensable for the interaction between PCBP1 and Tax. Moreover, PCBP1 facilitated the assembly of Tax/IKK complex. Collectively, our results demonstrated that PCBP1 may exert an essential effect in Tax/IKK complex combination and subsequent NF-κB activation, which provides a novel insight into the pathogenetic mechanisms of HTLV-1.

Clinical characteristics, genetic alterations, and prognosis of adult T-cell leukemia/lymphoma: an 11-year multicenter retrospective study in China

Adult T-cell leukemia/lymphoma (ATLL) is an aggressive malignancy with a poor prognosis, and there is little data available from the Chinese population. This retrospective study included 115 patients diagnosed with ATLL who were treated across five hospitals in China from June 2011 to December 2022. The median age at diagnosis was 53 years. Several genes involved in T-cell receptor-induced nuclear factor κB (TCR-NF-κB) signaling were commonly mutated, including PLCG1, CIC, PRKCB, CARD11, and IRF4. Eighty-seven patients received chemotherapy. Of these, 13 received a hematopoietic stem cell transplant (HSCT) (allogeneic-HSCT, n=9; autologous-HSCT, n=4) after chemotherapy. Following initial multiagent chemotherapy using EPOCH/CHOEP and other regimens, the overall response rates were 80.6% (complete response [CR], 44.4%) and 42.8% (CR, 14.2%), respectively. The 4-year survival rates (median survival time in days) for EPOCH/CHOEP (n=43), HSCT (n=13), and CHOP-based regimens (n=31) were 12.7% (138), 30.8% (333), and 0% (66), respectively. Lymphadenopathy, EPOCH/CHOEP, and hematopoietic stem cell transplantation were independent prognostic protective factors in patients with aggressive ATLL. Chinese patients exhibit a higher incidence of aggressive-type ATLL, sharing similar genetic alterations with Japanese patients. Etoposide-based chemotherapy (EPOCH or CHOEP) remains the preferred choice for aggressive ATLL, and upfront allogeneic HSCT should be considered in all eligible patients.

Complete Rescue of HTLV-1p12KO Infectivity by Depletion of Monocytes Together with NK and CD8+ T Cells

The transient depletion of monocytes alone prior to exposure of macaques to HTLV-1 enhances both HTLV-1WT (wild type) and HTLV-1p12KO (Orf-1 knockout) infectivity, but seroconversion to either virus is not sustained over time, suggesting a progressive decrease in virus expression. These results raise the hypotheses that either HTLV-1 persistence depends on a monocyte reservoir or monocyte depletion provides a transient immune evasion benefit. To test these hypotheses, we simultaneously depleted NK cells, CD8+ T cells, and monocytes (triple depletion) prior to exposure to HTLV-1WT or HTLV-1p12KO. Remarkably, triple depletion resulted in exacerbation of infection by both viruses and complete rescue of HTLV-1p12KO infectivity. Following triple depletion, we observed rapid and sustained seroconversion, high titers of antibodies against HTLV-1 p24Gag, and frequent detection of viral DNA in the blood and tissues of all animals when compared with depletion of only CD8+ and NK cells, or monocytes alone. The infection of macaques with HTLV-1WT or HTLV-1p12KO was associated with higher plasma levels of IL-10 after 21 weeks, while IL-6, IFN-γ, IL-18, and IL-1β were only elevated in animals infected with HTLV-1WT. The repeat depletion of monocytes, NK, and CD8+ cells seven months following the first exposure to HTLV-1 did not further exacerbate viral replication. These results underscore the contribution of monocytes in orchestrating anti-viral immunity. Indeed, the absence of orf-1 expression was fully compensated by the simultaneous depletion of CD8+ T cells, NK cells, and monocytes, underlining the primary role of orf-1 in hijacking host immunity.

Diversity of Human T-Lymphotropic Virus Type 1 Cosmopolitan Subtype (HTLV-1a) Circulating in Infected Residents in Portugal

Human T-cell lymphotropic virus type 1 (HTLV-1) prevalence in Portugal is low and mainly affects immigrants from endemic areas where human immunodeficiency virus (HIV) infection represents a public health problem. Despite the majority of HTLV-1-infected individuals remains asymptomatic, severe pathologies may develop after prolonged viral persistence, namely an aggressive form of leukemia. An increased mortality rate and faster progression to death is often related to HTLV-1/HIV coinfection. Nevertheless, studies showed that some antiretrovirals used in HIV treatment lead to a positive immune response against HTLV-1. This study aimed to analyze epidemiological and clinical data, and to assess the diversity of HTLV-1 strains circulating in infected residents diagnosed in the Portuguese national reference laboratory between 2010 and 2021. Long terminal repeat and env proviral sequences derived from 20 individuals were used to generate phylogenetic trees along with multiples reference sequences from different geographic origins retrieved from the database. Three samples belong to Portuguese natives and 17 belong to immigrants: 15 from several countries of Africa, 1 from South America, and 1 from Europe; 6 patients (30%, mean age 40.3 years) showed HTLV-1-related diseases, and 6 (30%, mean age 45.2 years) were coinfected with HIV/AIDS. The results show that the Cosmopolitan subtype is circulating in Portugal, with 10 sequences being classified as subgroup A, that include Portuguese and natives from S. Tomé and Príncipe with a mean age of 39.4 years, and 10 sequences that segregated into the Senegal cluster derived from natives born in Guinea-Bissau with a mean age of 43.5 years. A high proportion of HTLV-1-related diseases and HIV/AIDS coinfection was observed. Risk behavior practices and the absence of specific control measures, including diagnostic and treatment, may contribute to a silent dissemination of a broad diversity of HTLV-1 strains and, therefore, the increased rate of progression to debilitating diseases. In this manner, an early diagnostic and a molecular surveillance of HTLV-1 transmission remains necessary in Portugal.

Proteomic analysis of adult T-cell leukemia/lymphoma: A biomarker identification strategy based on preparation and in-solution digestion methods of total proteins

Adult T-cell leukemia/lymphoma (ATL), caused by human T-cell leukemia virus type-1 (HTLV-1) infection, is a malignant hematologic cancer that remains difficult to cure. We herein established a biomarker identification strategy based on the total cell proteomics of cultured ATL cells to search for novel ATL biomarkers. Four protocols with a combination of selected conditions based on lysis buffers and addition agents for total cell proteomics were used for a differential analysis between the ATL cell group (consisting of 11 cell lines), HTLV-1-infected cell group (consisting of 6 cell lines), and HTLV-1-negative cell group (consisting of 6 cell lines). In the analysis, we identified 24 and 27 proteins that were significantly increased (ratio ≥2.0, p < 0.05) and decreased (ratio ≤ 0.5, p < 0.05), respectively, in the ATL group. Previously reported CCL3 and CD30/TNFRSF8 were confirmed to be among significantly increased proteins. Furthermore, correlation analysis between identified proteins and Tax suggested that RASSF2 and GORASP2 were candidates of novel Tax-regulated factors. The biomarker identification strategy established herein is expected to contribute to the identification of biomarkers for ATL and other diseases.

Reduced CC Chemokine Receptor 4 Expression in Tumor Cells after Lenalidomide Treatment for Adult T-Cell Leukemia/Lymphoma: A Case Report

Introduction

CC chemokine receptor 4 (CCR4), which is involved in leukocyte migration, is expressed in most tumor cells in patients with adult T-cell leukemia/lymphoma (ATLL).

Case Presentation

Here we report the case of a 78-year-old man diagnosed with lymphoma-type ATLL expressing CCR4. The patient was administered two cycles of lenalidomide but died because of sepsis 5 months after the initial diagnosis. Autopsy revealed ATLL cells at several sites. Immunohistochemical analysis revealed that these ATLL cells had reduced CCR4 expression.

Conclusion

The present case suggests that treatment should be carefully determined in ATLL with reference to a history of lenalidomide use and CCR4 expression.

A population-based analysis of hematological malignancies from a French-West-Indies cancer registry's data (2009-2018)

BACKGROUND

A worldwide increased incidence of HM has been marked in recent decades. Therefore, to update epidemiological characteristics of HM in a French West Indies territory, we have performed analysis through Martinique's population-based cancer registry database.

METHODS

We included cancer case data, from 2009-2018, coded in strict compliance with international standards set by International Agency for Research on Cancer. We calculated standardized incidence rates, cumulative rate (ages 0-74), and temporal trends for cases and deaths using the global population standard, by sex and five age group. Mortality rates were obtained from the French Epidemiology Center on Medical Causes of Death (CépiDc).

RESULTS

One thousand forty seven new cases and 674 deaths from HM were recorded, of which 501 MM (47.8%), 377 LMNH (36%), 123 LAM (11.8%), and 46 LH (4.4%) were reported in both sexes. MM is one of the hematological malignancies with the highest incidence in Martinique among men. Temporal trends of incidence rates for all HM decreased overall in both sexes, except for MM in men. There is significant variability in mortality rates for both sexes. In addition, over the period, the temporal trends of mortality rates for all HMs has decreased overall. Gender-specific rates, between 2009 and 2018, showed that all lymphoid HM have a multimodal distribution curve that increased with age.

CONCLUSIONS

Characteristics of HM in Martinique over the reporting periods differ from mainland France. Higher incidences have been observed, particularly for MM, and non-significant sub-mortality is observed compared to mainland France. Moreover, temporal distribution of mortality and incidence trends had decreased over the reporting periods except for MM. Our results showed similarities with African-Americans groups in United States and in particular an equivalence in the frequency distribution of diagnosed HM. However, SMR remains lower compared to US black ethnic groups. Our results contributed to expanding knowledge on the epidemiology of HM with Caribbean data.

The Novel Link between Gene Expression Profiles of Adult T-Cell Leukemia/Lymphoma Patients' Peripheral Blood Lymphocytes and Ferroptosis Susceptibility

Ferroptosis, a regulated cell death dependent on iron, has garnered attention as a potential broad-spectrum anticancer approach in leukemia research. However, there has been limited ferroptosis research on ATL, an aggressive T-cell malignancy caused by HTLV-1 infection. Our study employs bioinformatic analysis, utilizing dataset GSE33615, to identify 46 ferroptosis-related DEGs and 26 autophagy-related DEGs in ATL cells. These DEGs are associated with various cellular responses, chemical stress, and iron-related pathways. Autophagy-related DEGs are linked to autophagy, apoptosis, NOD-like receptor signaling, TNF signaling, and the insulin resistance pathway. PPI network analysis revealed 10 hub genes and related biomolecules. Moreover, we predicted crucial miRNAs, transcription factors, and potential pharmacological compounds. We also screened the top 20 medications based on upregulated DEGs. In summary, our study establishes an innovative link between ATL treatment and ferroptosis, offering promising avenues for novel therapeutic strategies in ATL.

Measures for the Prevention of Mother-to-Child Human T-Cell Leukemia Virus Type 1 Transmission in Japan: The Burdens of HTLV-1-Infected Mothers

The main mode of mother-to-child transmission of the human T-cell leukemia virus (HTLV)-1 is through breastfeeding. Although the most reliable nutritional regimen to prevent HTLV-1 transmission is exclusive formula feeding, a recent meta-analysis revealed that short-term breastfeeding within 90 days does not increase the risk of infection. The protocol of the Japanese Health, Labor, and Welfare Science Research Group primarily recommended exclusive formula feeding for mothers who are positive for HTLV-1. However, there has been no quantitative research on the difficulties experienced by HTLV-1-positive mothers in carrying out these nutritional regimens, including the psychological burden. Therefore, this review was performed to clarify the burdens and difficulties encountered by mothers who are positive for HTLV-1; to this end, we analyzed the data registrants on the HTLV-1 career registration website "Carri-net" website. The data strongly suggest that it is not sufficient to simply recommend exclusive formula feeding or short-term breastfeeding as a means of preventing mother-to-child transmission; it is important for health care providers to understand that these nutritional regimens represent a major burden for pregnant women who are positive for HTLV-1 and to provide close support to ensure these women's health.

The Pleiotropic Effects of YBX1 on HTLV-1 Transcription

HTLV-1 is an oncogenic human retrovirus and the etiologic agent of the highly aggressive ATL malignancy. Two viral genes, Tax and Hbz, are individually linked to oncogenic transformation and play an important role in the pathogenic process. Consequently, regulation of HTLV-1 gene expression is a central feature in the viral lifecycle and directly contributes to its pathogenic potential. Herein, we identified the cellular transcription factor YBX1 as a binding partner for HBZ. We found YBX1 activated transcription and enhanced Tax-mediated transcription from the viral 5' LTR promoter. Interestingly, YBX1 also interacted with Tax. shRNA-mediated loss of YBX1 decreased transcript and protein abundance of both Tax and HBZ in HTLV-1-transformed T-cell lines, as well as Tax association with the 5' LTR. Conversely, YBX1 transcriptional activation of the 5' LTR promoter was increased in the absence of HBZ. YBX1 was found to be associated with both the 5' and 3' LTRs in HTLV-1-transformed and ATL-derived T-cell lines. Together, these data suggest that YBX1 positively influences transcription from both the 5' and 3' promoter elements. YBX1 is able to interact with Tax and help recruit Tax to the 5' LTR. However, through interactions with HBZ, YBX1 transcriptional activation of the 5' LTR is repressed.

Mouse Models for HTLV-1 Infection and Adult T Cell Leukemia

Adult T cell leukemia (ATL) is an aggressive hematologic disease caused by human T cell leukemia virus type 1 (HTLV-1) infection. Various animal models of HTLV-1 infection/ATL have been established to elucidate the pathogenesis of ATL and develop appropriate treatments. For analyses employing murine models, transgenic and immunodeficient mice are used because of the low infectivity of HTLV-1 in mice. Each mouse model has different characteristics that must be considered before use for different HTLV-1 research purposes. HTLV-1 Tax and HBZ transgenic mice spontaneously develop tumors, and the roles of both Tax and HBZ in cell transformation and tumor growth have been established. Severely immunodeficient mice were able to be engrafted with ATL cell lines and have been used in preclinical studies of candidate molecules for the treatment of ATL. HTLV-1-infected humanized mice with an established human immune system are a suitable model to characterize cells in the early stages of HTLV-1 infection. This review outlines the characteristics of mouse models of HTLV-1 infection/ATL and describes progress made in elucidating the pathogenesis of ATL and developing related therapies using these mice.

Prospects of early therapeutic interventions for indolent adult T-cell leukemia/lymphoma based on the chronic lymphocytic leukemia progression model

Adult T-cell leukemia/lymphoma (ATLL) has aggressive clinical behaviors, and improving its prognosis is a great challenge. A disease progression model from asymptomatic human T-cell leukemia virus type 1 carrier to aggressive-type ATLL has been proposed, and indolent ATLL comprising a smoldering or favorable chronic type is located at the midpoint. Even the most favorable smoldering type has a 4-year overall survival rate of <60%. Although watchful waiting is pervasive in patients with indolent ATLL, early therapeutic intervention is discussed among hematologists. Indolent ATLL was once termed T-cell-derived chronic lymphocytic leukemia (CLL). Unlike indolent ATLL, several molecular-targeted agents at the initial treatment have dramatically improved CLL prognosis. Recent studies on CLL have revealed a similar progression model involving premalignant monoclonal B-cell lymphocytosis (MBL). In particular, individuals with high-count MBL have an increased lymphoma risk. Considering the unsatisfactory long-term prognosis of indolent ATLL, further treatment strategies, including precision medicine, are warranted.

CD30 Expression and Its Functions during the Disease Progression of Adult T-Cell Leukemia/Lymphoma

CD30, a member of the tumor necrosis factor receptor superfamily, plays roles in pro-survival signal induction and cell proliferation in peripheral T-cell lymphoma (PTCL) and adult T-cell leukemia/lymphoma (ATL). Previous studies have identified the functional roles of CD30 in CD30-expressing malignant lymphomas, not only PTCL and ATL, but also Hodgkin lymphoma (HL), anaplastic large cell lymphoma (ALCL), and a portion of diffuse large B-cell lymphoma (DLBCL). CD30 expression is often observed in virus-infected cells such as human T-cell leukemia virus type 1 (HTLV-1). HTLV-1 is capable of immortalizing lymphocytes and producing malignancy. Some ATL cases caused by HTLV-1 infection overexpress CD30. However, the molecular mechanism-based relationship between CD30 expression and HTLV-1 infection or ATL progression is unclear. Recent findings have revealed super-enhancer-mediated overexpression at the CD30 locus, CD30 signaling via trogocytosis, and CD30 signaling-induced lymphomagenesis in vivo. Successful anti-CD30 antibody-drug conjugate (ADC) therapy for HL, ALCL, and PTCL supports the biological significance of CD30 in these lymphomas. In this review, we discuss the roles of CD30 overexpression and its functions during ATL progression.

Human T-cell lymphotropic virus type 1 (HTLV-1) proposed vaccines: a systematic review of preclinical and clinical studies

BACKGROUND

Numerous vaccination research experiments have been conducted on non-primate hosts to prevent or control HTLV-1 infection. Therefore, reviewing recent advancements for status assessment and strategic planning of future preventative actions to reduce HTLV-1 infection and its consequences would be essential.

METHODS

MEDLINE, Scopus, Web of Science, and Clinicaltrials.gov were searched from each database's inception through March 27, 2022. All original articles focusing on developing an HTLV-1 vaccine candidate were included.

RESULTS

A total of 47 studies were included. They used a variety of approaches to develop the HTLV-1 vaccine, including DNA-based, dendritic-cell-based, peptide/protein-based, and recombinant vaccinia virus approaches. The majority of the research that was included utilized Tax, Glycoprotein (GP), GAG, POL, REX, and HBZ as their main peptides in order to develop the vaccine. The immunization used in dendritic cell-based investigations, which were more recently published, was accomplished by an activated CD-8 T-cell response. Although there hasn't been much attention lately on this form of the vaccine, the initial attempts to develop an HTLV-1 immunization depended on recombinant vaccinia virus, and the majority of results seem positive and effective for this type of vaccine. Few studies were conducted on humans. Most of the studies were experimental studies using animal models. Adenovirus, Cytomegalovirus (CMV), vaccinia, baculovirus, hepatitis B, measles, and pox were the most commonly used vectors.

CONCLUSIONS

This systematic review reported recent progression in the development of HTLV-1 vaccines to identify candidates with the most promising preventive and therapeutic effects.

Heat shock factor 1 is a promising therapeutic target against adult T-cell leukemia

Patients with adult T-cell leukemia (ATL), which is caused by human T-cell leukemia virus type 1 (HTLV-1), show poor prognosis because of drug resistance. Heat shock protein (HSP) 90 is reportedly essential for ATL cell survival as it regulates important signaling pathways, thereby making HSP90 inhibitors new therapeutic candidates for ATL. However, HSP90 inhibition increases the expression of other HSPs, suggesting that HSPs may contribute to drug resistance. The heat shock factor 1 (HSF1) transcription factor is the primary regulator of the expression of HSPs. Furthermore, targeting HSF1 disrupts the HSP90 chaperone function. Herein, we demonstrated that HSF1 is overexpressed in HTLV-1-infected T cells. HSF1 knockdown inhibited the proliferation of HTLV-1-infected T cells. HSF1 inhibitor KRIBB11 reduced the expression and phosphorylation of HSF1, downregulated HSP70 and HSP27 expression, and suppressed Akt, nuclear factor-κB, and AP-1 signals. KRIBB11 treatment induced DNA damage, upregulated p53 and p21, and reduced the expression of cyclin D2/E, CDK2/4, c-Myc, MDM2, and β-catenin, thereby preventing retinoblastoma protein phosphorylation and inhibiting G1-S cell cycle progression. KRIBB11 also induced caspase-mediated apoptosis concomitant with the suppression of Bcl-xL, Mcl-1, XIAP, c-IAP1/2, and survivin expression. KRIBB11 inhibited HSP70 and HSP90 upregulation through treatment with AUY922, an HSP90 inhibitor, and enhanced the cytotoxic effect of AUY922, suggesting a salvage role of HSF1-dependent HSP induction in response to drug treatment. Finally, treatment of mice with KRIBB11 reduced ATL tumor growth. Therefore, this study provides a strong rationale to target HSF1 and validates the anti-ATL activity of KRIBB11.

How Can We Prevent Mother-to-Child Transmission of HTLV-1?

The perception of human T-cell leukemia virus type 1 (HTlV-1) infection as a "silent disease" has recently given way to concern that its presence may be having a variety of effects. HTLV-1 is known to cause adult T-cell leukemia (ATL), an aggressive cancer of peripheral CD4 T cells; however, it is also responsible for HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Most patients develop ATL as a result of HTLV-1 mother-to-child transmission. The primary route of mother-to-child transmission is through the mother's milk. In the absence of effective drug therapy, total artificial nutrition such as exclusive formula feeding is a reliable means of preventing mother-to-child transmission after birth, except for a small percentage of prenatal infections. A recent study found that the rate of mother-to-child transmission with short-term breastfeeding (within 90 days) did not exceed that of total artificial nutrition. Because these preventive measures are in exchange for the benefits of breastfeeding, clinical applications of antiretroviral drugs and immunotherapy with vaccines and neutralizing antibodies are urgently needed.

Malignancy and viral infections in Sub-Saharan Africa: A review

The burden of malignancy related to viral infection is increasing in Sub-Saharan Africa (SSA). In 2018, approximately 2 million new cancer cases worldwide were attributable to infection. Prevention or treatment of these infections could reduce cancer cases by 23% in less developed regions and about 7% in developed regions. Contemporaneous increases in longevity and changes in lifestyle have contributed to the cancer burden in SSA. African hospitals are reporting more cases of cancer related to infection (e.g., cervical cancer in women and stomach and liver cancer in men). SSA populations also have elevated underlying prevalence of viral infections compared to other regions. Of 10 infectious agents identified as carcinogenic by the International Agency for Research on Cancer, six are viruses: hepatitis B and C viruses (HBV and HCV, respectively), Epstein-Barr virus (EBV), high-risk types of human papillomavirus (HPV), Human T-cell lymphotropic virus type 1 (HTLV-1), and Kaposi's sarcoma herpesvirus (KSHV, also known as human herpesvirus type 8, HHV-8). Human immunodeficiency virus type 1 (HIV) also facilitates oncogenesis. EBV is associated with lymphomas and nasopharyngeal carcinoma; HBV and HCV are associated with hepatocellular carcinoma; KSHV causes Kaposi's sarcoma; HTLV-1 causes T-cell leukemia and lymphoma; HPV causes carcinoma of the oropharynx and anogenital squamous cell cancer. HIV-1, for which SSA has the greatest global burden, has been linked to increasing risk of malignancy through immunologic dysregulation and clonal hematopoiesis. Public health approaches to prevent infection, such as vaccination, safer injection techniques, screening of blood products, antimicrobial treatments and safer sexual practices could reduce the burden of cancer in Africa. In SSA, inequalities in access to cancer screening and treatment are exacerbated by the perception of cancer as taboo. National level cancer registries, new screening strategies for detection of viral infection and public health messaging should be prioritized in SSA's battle against malignancy. In this review, we discuss the impact of carcinogenic viruses in SSA with a focus on regional epidemiology.

Current and emerging therapeutic strategies in adult T-cell leukemia-lymphoma

Adult T-cell leukemia-lymphoma (ATL) is classified into four clinical subtypes: acute, lymphoma, chronic, and smoldering. Chronic ATL is further divided into unfavorable and favorable chronic types according to serum lactate dehydrogenase, blood urea nitrogen, and serum albumin values. Acute, lymphoma, and unfavorable chronic types are categorized as aggressive ATL, whereas favorable chronic and smoldering types are categorized as indolent ATL. Intensive chemotherapy alone is not sufficient to prevent relapse of aggressive ATL. Allogeneic hematopoietic stem cell transplantation is a potential therapeutic option to cure aggressive ATL in younger patients. Reduced-intensity conditioning regimens have decreased transplantation-related mortality, and increased donor availability has dramatically improved transplant access. New agents, including mogamulizumab, brentuximab vedotin, tucidinostat, and valemetostat, have recently become available for patients with aggressive ATL in Japan. Here, I provide an overview of recent advances in therapeutic strategies for ATL.

Genomic landscape of virus-associated cancers

It has been estimated that 15%-20% of human cancers are attributable to infections, mostly by carcinogenic viruses. The incidence varies worldwide, with a majority affecting developing countries. Here, we present a comparative analysis of virus-positive and virus-negative tumors in nine cancers linked to five viruses. We find that virus-positive tumors occur more frequently in males and show geographical disparities in incidence. Genomic analysis of 1,658 tumors reveals virus-positive tumors exhibit distinct mutation signatures and driver gene mutations and possess a lower somatic mutation burden compared to virus-negative tumors of the same cancer type. For example, compared to the respective virus-negative counterparts, virus-positive cases across different cancer histologies had less often mutations of TP53 and deletions of 9p21.3/ CDKN2 A- CDKN1A ; Epstein-Barr virus-positive (EBV+) gastric cancer had more frequent mutations of EIF4A1 and ARID1A and less marked mismatch repair deficiency signatures; and EBV-positive cHL had fewer somatic genetic lesions of JAK-STAT, NF-κB, PI3K-AKT and HLA-I genes and a less pronounced activity of the aberrant somatic hypermutation signature. In cHL, we also identify germline homozygosity in HLA class I as a potential risk factor for the development of EBV-positive Hodgkin lymphoma. Finally, an analysis of clinical trials of PD-(L)1 inhibitors in four virus-associated cancers suggested an association of viral infection with higher response rate in patients receiving such treatments, which was particularly evident in gastric cancer and head and neck squamous cell carcinoma. These results illustrate the epidemiological, genetic, prognostic, and therapeutic trends across virus-associated malignancies.

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.

Advances in the treatment of HTLV-1-associated adult T-cell leukemia lymphoma

Adult T-cell leukemia/lymphoma (ATLL) is an aggressive hematologic malignancy linked to HTLV-1 infection, which is refractory to therapy. The precise mechanism of oncogenesis in ATLL is incompletely understood, however, oncogenic viral genes Tax and Hbz are implicated, and recent large genomic and transcriptome studies provide further insight. Despite progress in understanding the disease, survival and outcome with current therapies remain poor. Long-term survivors are reported, primarily among those with indolent disease or activating CC chemokine receptor 4 mutations, however, allogeneic hematopoietic stem cell transplant is the only curative treatment option. The majority of patients succumb to their disease and ongoing and collaborative research efforts are needed. I will review recent updates in HTLV-1-associated ATLL epidemiology, pathogenesis, therapy, and prevention.

Geographic distribution, clinical epidemiology and genetic diversity of the human oncogenic retrovirus HTLV-1 in Africa, the world's largest endemic area

The African continent is considered the largest high endemic area for the oncogenic retrovirus HTLV-1 with an estimated two to five million infected individuals. However, data on epidemiological aspects, in particular prevalence, risk factors and geographical distribution, are still very limited for many regions: on the one hand, few large-scale and representative studies have been performed and, on the other hand, many studies do not include confirmatory tests, resulting in indeterminate serological results, and a likely overestimation of HTLV-1 seroprevalence. For this review, we included the most robust studies published since 1984 on the prevalence of HTLV-1 and the two major diseases associated with this infection in people living in Africa and the Indian Ocean islands: adult T-cell leukemia (ATL) and tropical spastic paraparesis or HTLV-1-associated myelopathy (HAM/TSP). We also considered most of the book chapters and abstracts published at the 20 international conferences on HTLV and related viruses held since 1985, as well as the results of recent meta-analyses regarding the status of HTLV-1 in West and sub-Saharan Africa. Based on this bibliography, it appears that HTLV-1 distribution is very heterogeneous in Africa: The highest prevalences of HTLV-1 are reported in western, central and southern Africa, while eastern and northern Africa show lower prevalences. In highly endemic areas, the HTLV-1 prevalence in the adult population ranges from 0.3 to 3%, increases with age, and is highest among women. In rural areas of Gabon and the Democratic Republic of the Congo (DRC), HTLV-1 prevalence can reach up to 10-25% in elder women. HTLV-1-associated diseases in African patients have rarely been reported in situ on hospital wards, by local physicians. With the exception of the Republic of South Africa, DRC and Senegal, most reports on ATL and HAM/TSP in African patients have been published by European and American clinicians and involve immigrants or medical returnees to Europe (France and the UK) and the United States. There is clearly a huge underreporting of these diseases on the African continent. The genetic diversity of HTLV-1 is greatest in Africa, where six distinct genotypes (a, b, d, e, f, g) have been identified. The most frequent genotype in central Africa is genotype b. The other genotypes found in central Africa (d, e, f and g) are very rare. The vast majority of HTLV-1 strains from West and North Africa belong to genotype a, the so-called 'Cosmopolitan' genotype. These strains form five clades roughly reflecting the geographic origin of the infected individuals. We have recently shown that some of these clades are the result of recombination between a-WA and a-NA strains. Almost all sequences from southern Africa belong to Transcontinental a-genotype subgroup.

CDK9 Inhibitor Induces Apoptosis, Autophagy, and Suppression of Tumor Growth in Adult T-Cell Leukemia/Lymphoma

Adult T-cell leukemia/lymphoma (ATL) is a hematopoietic malignancy with a poor prognosis that develops in approximately 5% of human T-cell leukemia virus type 1 (HTLV-1) carriers. Cyclin-dependent kinase 9 (CDK9), together with Cyclin T, forms a transcription elongation factor, positive transcription elongation factor b (P-TEFb). P-TEFb promotes transcriptional elongation by phosphorylating the second serine (Ser2) of the seven amino acid repeat sequence in the C-terminal domain of RNA polymerase II (RNAP II). CDK9 inhibitors suppress cell proliferation by inducing apoptosis in chronic lymphocytic leukemia and breast cancer but there are no reports on autophagy of CDK9 inhibitors. Here, we investigated the effect of LY2857785, a novel CDK9 selective inhibitor, on cell death in ATL-related cell lines in vitro, freshly isolated cells from ATL patients ex vivo, and on ATL tumor xenografts in NOD/SCID mice in vivo. LY2857785 significantly reduced cell viability and induced apoptosis, as shown by annexin V-positive cells, cleaved poly(ADP-ribose) polymerase (PARP), and cleaved caspase-3, and suppressed the levels of anti-apoptotic protein myeloid cell leukemia-1 (MCL-1). LY2857785 decreased RNAP II Ser2 phosphorylation and downstream c-Myc protein levels. Interestingly, LY2857785 also increased microtubule-associated proteins 1A/1B light chain 3B (LC3)-II binding to autophagosome membranes. Furthermore, LY2857785 decreased the viability of freshly isolated ATL cells and induced apoptosis. Finally, LY2857785 significantly decreased the growth of ATL tumor xenografts. These results suggest that LY2857785 induces cell death of ATL cells by MCL-1-dependent apoptosis and autophagy and has anti-tumor activity.

Valemetostat: First approval as a dual inhibitor of EZH1/2 to treat adult T-cell leukemia/lymphoma

Adult T-cell leukemia/lymphoma (ATL) is a mature T-cell lymphoma with a poor prognosis. Accumulating trimethylation of histone H3 lysine 27 (H3K27me3) caused by upregulated function of either enhancer of zeste homologue 2 (EZH2) or its homolog EZH1 plays an essential role in the maintenance of transcriptional repression in ATL. Selective inhibition of EZH2 may complementarily induce EZH1 activation, so dual targeting EZH1/2 is a rational strategy in developing potent antitumor agents. Valemetostat is the first dual EZH1/2 inhibitor approved for treatment of aggressive ATL in Japan in September 2022. Several other dual EZH1/2 inhibitors such as HH2853, HM97594, and HM97662 have also demonstrated potential in treating malignant tumors. Dual targeting EZH1/2 may have promising antitumor action in hematological malignancies and solid tumors.

The oncogenic driving force of CD30 signaling-induced chromosomal instability in adult T-cell leukemia/lymphoma

Adult T-cell leukemia/lymphoma (ATL) develops via stepwise accumulation of gene mutations and chromosome aberrations. However, the molecular mechanisms underlying this tumorigenic process are poorly understood. We previously reported the presence of a biological link between the expression of CD30, which serves as a marker for ATL progression, and the actively proliferating fraction of human T-cell leukemia virus type 1 (HTLV-1)-infected cells that display polylobulation. Here, we demonstrated that CD30 signaling induced chromosomal instability with clonal expansion through DNA double-strand breaks (DSBs) via an increase of intracellular reactive oxygen species. CD30⁺ ATL cells were composed of subclones with additional genomic aberrations compared with CD30^- ATL cells in ATL patients. Furthermore, we found an accumulation of copy number loss of DSB repair-related genes as the disease progressed. Taken together, CD30 expression on ATL cells appears to be correlated with genomic instability, suggesting that CD30 signaling is one of the oncogenic factors of ATL progression with clonal evolution. This study provides new insight into the biological roles of CD30 signaling and could improve our understanding of tumorigenic processes of HTLV-1-infected cells.

Decline in human T-cell lymphotropic virus seroprevalence in blood donors from Minas Gerais, Brazil over a 12-year period (2006-2017)

To investigate a 12-year historical series (2006-2017) of human T-cell lymphotropic virus (HTLV)-positive blood donations from Fundação Hemominas, Minas Gerais, Brazil, an observational retrospective study was performed to evaluate data of blood donor candidates who were screened for HTLV-1/2 by enzyme-linked immunosorbent assay or chemiluminescence assays and confirmed by Western blot. We analyzed 3 309 716 blood donations covering 2006-2017 that were extracted from the institutional database. In a total of 3 308 738 donations that have complete algorithm tests, the global frequency of HTLV-positive donations was 0.012%. The seroprevalence in first-time blood donors was 28.82/100 000 donors; 0.95/100 000 donations were HTLV-positive in repeat blood donors. The frequency of HTLV-seropositive females was significantly higher than males (odds ratio = 1.85, p < 0.001) in first-time donors. The median age of HTLV-positive first-time and repeat donors was similar (36 and 32 years, respectively). First-time donors ≥41 years had higher odds to be infected. There was a clear tendency of decline in the HTLV-positive donations in the period analyzed, going from 19.26/100 000 donations to 8.50/100 000 donations. The increase in the proportion of repeat donors over the period analyzed (from 23% in 2006 to 67% in 2017) must be the principal factor that contributed to this drop. Our results showed a continuous decline in the frequency of HTLV-positive donations from Minas Gerais, Brazil throughout 12 years and emphasize the importance of having a high rate of repeat donors in blood centers to reduce the residual risk of transfusion-transmitted infections.

The importance of the clinical classification of adult T-cell leukemia/lymphoma (ATLL) in the prognosis

BACKGROUND

Adult T-cell leukemia/lymphoma (ATLL), a peripheral T-cell leukemia/lymphoma associated with the human T-cell lymphotropic virus type-1 (HTLV-1), has been classified following the clinical forms defined by Shimoyama in 1991. A suggestion to modify Shimoyama's classification was proposed in 2007 to differentiate within the smoldering patients those who presented nodules or tumors in the skin without lung involvement, which was named the primary cutaneous tumoral (PCT) form of ATLL. In the present study, according to their clinicopathological characteristics, we estimated the mortality rates of 143 ATLL patients from Bahia, Brazil. We also evaluated the importance of classifying PCT/ATLL separately from the smoldering type on disease prognosis.

METHODOLOGY/PRINCIPAL FINDINGS

Diagnosis of ATLL was established based on a positive serology for HTLV-1, histopathological and/or cytological diagnosis of peripheral T-cell leukemia/lymphoma. Patients were clinically grouped according to Shimoyama's classification, considering PCT variants separately from the smoldering cases. Bivariate and multivariable survival analyses were applied to identify factors associated with disease prognosis. Significant differences in the median survival time were observed between the clinical types, with the smoldering type presenting the longest median survival (109 months) compared to the other forms (<50 months); the median survival for PCT/ATLL was 20 months. Multivariable analysis confirmed that ATLL clinical types were associated with survival, with a better prognosis for patients with the smoldering and chronic types. Furthermore, skin involvement was related to a worse outcome in the multivariable analysis, regardless of the clinical form and presence of lymphadenopathy.

CONCLUSIONS/SIGNIFICANCE

Our results reinforce the importance of considering the PCT/ATLL separately from the smoldering type when classifying ATLL to better define prognosis and treatment, given the significant difference in the survival of patients between the smoldering form and PCT/ATLL. Skin involvement should also be considered an independent prognostic factor in patients with ATLL.

Prevalence and Risk Factors for HTLV-1/2 Infection inRiverside and Rural Populations of the State of Pará

Human T-lymphotropic viruses 1 and 2 (HTLV-1 and HTLV-2) infection has been described in several Amazonian populations; however, there is still a lack of data on the prevalence of the virus in riparian populations living in rural areas of the state of Pará. The present study aimed to evaluate the prevalence of HTLV-1/2 infection in four riverine communities and one rural area in the state of Pará and to describe the possible risk factors for infection. A total of 907 individuals responded to an epidemiological survey and gave blood samples collected for anti-HTLV-1/2 antibodies by immunoenzymatic assay (EIA). The serum-reactive samples were subjected to confirmation by an in-line assay (Inno-Lia) and by proviral DNA screening using real-time PCR (qPCR). The total prevalence was 0.8% (7/907) for HTLV-1/2 (CI: 0.2−1.3%), with 0.66% HTLV-1 and 0.11% HTLV-2. The prevalence by sex was 0.7% in women (4/565) and 0.9% in men (3/342). Among seropositive patients, 83.3% (5/7) reported being sexually active, and 57.1% (4/7) reported not having the habit of using condoms during their sexual relations. Intrafamily infection was also observed. The results reinforce the need for public policies to prevent and block the spread of HTLV, especially in riparian communities that are subject to difficulties in accessing the Unified Health System (Sistema Único de Saúde/SUS) because infected individuals need clinical monitoring for surveillance and early diagnosis of symptoms associated with HTLV-1.

Tuning Rex rules HTLV-1 pathogenesis

HTLV-1 is an oncovirus causing ATL and other inflammatory diseases such as HAM/TSP and HU in about 5% of infected individuals. It is also known that HTLV-1-infected cells maintain a disease-free, immortalized, latent state throughout the lifetimes of about 95% of infected individuals. We believe that the stable maintenance of disease-free infected cells in the carrier is an intrinsic characteristic of HTLV-1 that has been acquired during its evolution in the human life cycle. We speculate that the pathogenesis of the virus is ruled by the orchestrated functions of viral proteins. In particular, the regulation of Rex, the conductor of viral replication rate, is expected to be closely related to the viral program in the early active viral replication followed by the stable latency in HTLV-1 infected T cells. HTLV-1 and HIV-1 belong to the family Retroviridae and share the same tropism, e.g., human CD4+ T cells. These viruses show significant similarities in the viral genomic structure and the molecular mechanism of the replication cycle. However, HTLV-1 and HIV-1 infected T cells show different phenotypes, especially in the level of virion production. We speculate that how the activity of HTLV-1 Rex and its counterpart HIV-1 Rev are regulated may be closely related to the properties of respective infected T cells. In this review, we compare various pathological aspects of HTLV-1 and HIV-1. In particular, we investigated the presence or absence of a virally encoded "regulatory valve" for HTLV-1 Rex or HIV-1 Rev to explore its importance in the regulation of viral particle production in infected T cells. Finally, wereaffirm Rex as the key conductor for viral replication and viral pathogenesis based on our recent study on the novel functional aspects of Rex. Since the activity of Rex is closely related to the viral replication rate, we hypothesize that the "regulatory valve" on the Rex activity may have been selectively evolved to achieve the "scenario" with early viral particle production and the subsequent long, stable deep latency in HTLV-1 infected cells.

T cell receptor repertoire analysis in HTLV-1-associated diseases

Human T lymphotropic virus 1 (HTLV-1) is a human retrovirus identified as the causative agent in adult T-cell leukemia/lymphoma (ATL) and chronic-progressive neuroinflammatory disorder HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). HTLV-1 is estimated to infect between 5-20 million people worldwide, although most infected individuals remain asymptomatic. HTLV-1 infected persons carry an estimated lifetime risk of approximately 5% of developing ATL, and between 0.25% and 1.8% of developing HAM/TSP. Most HTLV-1 infection is detected in CD4⁺ T cells in vivo which causes the aggressive malignancy in ATL. In HAM/TSP, the increase of HTLV-1 provirus induces immune dysregulation to alter inflammatory milieu, such as expansion of HTLV-1-specific CD8⁺ T cells, in the central nervous system of the infected subjects, which have been suggested to underlie the pathogenesis of HAM/TSP. Factors contributing to the conversion from asymptomatic carrier to disease state remain poorly understood. As such, the identification and tracking of HTLV-1-specific T cell biomarkers that may be used to monitor the progression from primary infection to immune dysfunction and disease are of great interest. T cell receptor (TCR) repertoires have been extensively investigated as a mechanism of monitoring adaptive T cell immune response to viruses and tumors. Breakthrough technologies such as single-cell RNA sequencing have increased the specificity with which T cell clones may be characterized and continue to improve our understanding of TCR signatures in viral infection, cancer, and associated treatments. In HTLV-1-associated disease, sequencing of TCR repertoires has been used to reveal repertoire patterns, diversity, and clonal expansions of HTLV-1-specific T cells capable of immune evasion and dysregulation in ATL as well as in HAM/TSP. Conserved sequence analysis has further been used to identify CDR3 motif sequences and exploit disease- or patient-specificity and commonality in HTLV-1-associated disease. In this article we review current research on TCR repertoires and HTLV-1-specific clonotypes in HTLV-1-associated diseases ATL and HAM/TSP and discuss the implications of TCR clonal expansions on HTLV-1-associated disease course and treatments.

Epidemiology of Adult T-Cell Leukaemia/Lymphoma in South Africa over a 10-Year Period

Introduction

Adult T-cell leukaemia/lymphoma (ATLL) is a rare and aggressive malignancy of mature T-cells. Limited epidemiological studies have shown that there is substantial variation in age at diagnosis and subtype distribution between different geographical regions. This is the first epidemiological study of ATLL in South Africa.

Methods

A national epidemiological study of ATLL in South Africa was performed. All new cases of ATLL from 2009 to 2019 were identified by laboratory database search in public and private health care sectors. Demographic and diagnostic data were obtained, and the cases were subtyped according to the Shimoyama classification.

Results

There were 31 patients with ATLL over the 10-year period, with an incidence of 0.06 per 100000 population. The male to female ratio was 1 : 1 and the median age at diagnosis was 37 years. Acute ATLL was the most commonly seen subtype in South Africa.

Conclusion

In this, the first epidemiological study of ATLL in South Africa, we demonstrate that ATLL is a rare disease, that acute ATLL is the most commonly diagnosed subtype, and that ATLL is likely under diagnosed. Patients present at a considerably younger age than the reported age in other nations.

High incidence of serious infections requiring hospitalisation in human T-cell leukaemia virus type 1-positive rheumatoid arthritis: A case-controlled observational study

OBJECTIVES

We aimed to assess the clinical features of human T-cell leukaemia virus type 1 (HTLV-1)-positive rheumatoid arthritis (RA) patients. Furthermore, we investigated the impact of HTLV-1 infection on incidences of serious infections requiring hospitalisation (SIH) and malignancies.

METHODS

A total of 150 sex- and age-matched HTLV-1-negative and 50 HTLV-1-positive RA patients were enrolled from the HTLV-1 RA Miyazaki Cohort Study. Clinical and laboratory data were collected from this cohort database. The incidence rate (IR) for SIH and malignancies from 2015 to 2020 was analysed.

RESULTS

The median age and female ratio in the study population were 70 years old and 80%, respectively. Although no differences were found in inflammatory marker values between the two groups, the patient global assessment and Health Assessment Questionnaire scores were higher in HTLV-1-positive RA patients. In HTLV-1-negative RA patients, the IR for SIH was 6.37/100 person-years (PY) and 1.32/100 PY for malignancies. In HTLV-1-positive RA patients, SIH occurred in 11.1/100 PY and malignancies in 2.46/100 PY. The crude IR ratio comparing SIH between two groups was 1.74 (95% confidence interval, 1.04-2.84), which was a significant increase.

CONCLUSIONS

HTLV-1-positive RA patients may worsen RA symptoms. HTLV-1 may be a risk factor for SIH.

Exportin-1 is critical for cell proliferation and survival in adult T cell leukemia

Since treatment options for adult T cell leukemia (ATL) associated with human T cell leukemia virus type 1 (HTLV-1) fail to obtain long-term response, novel therapies targeting ATL-dysregulated pathways are necessary. Dysregulated nuclear import and export machinery is common in malignancies. This study aimed to investigate the potential of exportin-1 (XPO1), which mediates nuclear export of cargos, as a target in ATL. RT-PCR and western blotting were performed to determine XPO1 expression. We evaluated XPO1's effects on cell proliferation and viability through WST-8 assays, cell cycle and apoptosis via Hoechst 33342 staining and flow cytometry, and intracellular signaling cascades using western blotting. XPO1 expression was upregulated in HTLV-1-infected T cells. XPO1 knockdown reduced cell proliferation. XPO1 inhibitor KPT-330 also reduced proliferation, increased DNA damage, and induced G1 cell cycle arrest and caspase-dependent apoptosis. KPT-330 downregulated cell cycle regulators (CDK2/4/6, cyclin D2, c-Myc and phosphorylated pRb) and anti-apoptotic proteins (XIAP, c-IAP1/2, survivin and Mcl-1), and upregulated p53, p21 and Bak. KPT-330 suppressed XPO1 and increased the nuclear localization of cargos (NF-κB RelA and its negative regulator IκBα, protein phosphatase 2A and its inhibitor SET, p53 and its negative regulator MDM2, p21, p27, FOXO1 and pRb). KPT-330 treatment resulted in the abrogation of aberrant pathways (NF-κB, Akt and STAT3/5) simultaneously through the activation of tumor suppressor proteins and inhibition of oncogenes and proliferative/survival factors. These findings encourage investigating the use of KPT-330 in clinical trials targeting ATL.