Pivotal role of dihydroorotate dehydrogenase as a therapeutic target in adult T-cell leukemia.

OBJECTIVES: We aimed to determine the role of dihydroorotate dehydrogenase (DHODH) in pathogenesis of adult T-cell leukemia (ATL) caused by human T-cell leukemia virus type 1 (HTLV-1) and the effects of its inhibition on the de novo pyrimidine biosynthesis pathway. METHODS: Cell proliferation, viability, cycle, and apoptosis were analyzed using WST-8 assays, flow cytometry, and Hoechst 33342 staining. To elucidate the molecular mechanisms involved in the anti-ATL effects of DHODH knockdown and inhibition, RT-PCR and immunoblotting were conducted. RESULTS: HTLV-1-infected T-cell lines aberrantly expressed DHODH. Viral infection and the oncoprotein, Tax, enhanced DHODH expression, while knockdown of DHODH decreased HTLV-1-infected T-cell growth. In addition, BAY2402234, a DHODH inhibitor, exerted an anti-proliferative effect, which was reversed by uridine supplementation. BAY2402234 induced DNA damage and S phase arrest by downregulating c-Myc, CDK2, and cyclin A and upregulating p53 and cyclin E. It also induced caspase-mediated apoptosis by the upregulation of pro-apoptotic and downregulation of anti-apoptotic proteins. Furthermore, BAY2402234 induced caspase-independent ferroptosis and necroptosis. It decreased phosphorylation of IKK, IκBα, PTEN, Akt, and its downstream targets, suggesting that inhibition of NF-κB and Akt signaling is involved in its anti-ATL action. CONCLUSION: These findings highlight DHODH as a potential therapeutic target for treating ATL.

Poor Outcome of Adult T-Cell Leukemia/Lymphoma with Current Available Therapy: An Experience of Two Centers.

INTRODUCTION: Adult T-cell leukemia lymphoma (ATLL) is an aggressive mature T-cell neoplasm caused by human T-cell lymphotropic virus type 1 (HTLV-1) infection. Despite its poor prognosis, there is no standard therapy for ATLL due to its low incidence and the disease affecting only endemic geographical clusters. METHODS: A retrospective evaluation of patients with the diagnosis of ATLL at Moffitt Cancer Center and Memorial Healthcare System was done to identify patients and disease characteristics along with the progression-free survival (PFS) and overall survival (OS) for the different therapies used. RESULTS: The 61 patients analyzed showed a median age of 58 with 82.5% of them being of African American descent. The acute variant contributed to the majority of cases (43.9%), followed by 36.8% presenting as a lymphoma variant. There was no statistical difference in the PFS (6.4 m, 3.1 m, 2.1 m; p = 0.23) or OS (14 m, 8.9 m, 18.5 m; p = 0.14) between cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP), intensive chemotherapy regimens, and other modalities, respectively. However, the patients who had complete or partial remission with first-line therapy had better OS (15.9 m vs. 7.2 m; p = 0.004). CONCLUSIONS: The study highlighted the poor outcome of the current regimens and the lack of a unifying protocol for this vicious disease. The acute variants were treated with more intensive regimens, but there was no difference in the OS between the three major options of CHOP, intensified chemotherapy, and others. This underscores the need for more clinical trials to develop better outcomes.

[Adult T-cell leukemia/lymphoma: progress in understanding of pathogenesis and treatment].

Adult T-cell leukemia/lymphoma (ATL) is an exceedingly refractory peripheral T-cell lymphoma. Despite the approval of a few new drugs for managing patients with newly diagnosed or relapsed/refractory ATL in recent years, the prognosis has yet to be substantially ameliorated. This study focuses on recent topics on the development of innovative therapies and the identification of prognostic indicators, considering the recent elucidation of the pathogenesisof ATL. Specifically, this study also delineates the advancements in developing novel EZH1/2 inhibitors and comprehensive genetic analysis; the molecular pathogenesis determined through comprehensive gene knockdown and knockout techniques, with its potential as a therapeutic target; the latest discoveries from the analysis of super-enhancer regions; and the prognostic factors extracted from comprehensive genetic analysis.

Treatment of Adult T-Cell Leukemia/Lymphoma: Established Paradigms and Emerging Directions.

OPINION STATEMENT: Adult T-cell leukemia/lymphoma (ATL) is a rare, aggressive subtype of peripheral T-cell lymphoma developing after many years of chronic, asymptomatic infection with the retrovirus human T-cell lymphotropic virus type 1 (HTLV-1). HTLV-1 is endemic to certain geographic areas of the world, and primary infection generally occurs in infancy through mother-to-child transmission via breastfeeding. In less than 5% of infected individuals, a decades-long pathogenic process culminates in the development of ATL. Aggressive subtypes of ATL are life-threatening and challenging to treat, with median overall survival typically less than 1 year in the absence of allogeneic hematopoietic cell transplantation (alloHCT). Owing to the rarity of this illness, prospective large-scale clinical trials have been challenging to perform, and treatment recommendations are largely founded upon limited evidence. Herein, we review the current therapeutic options for ATL, providing a broad literature overview of the foremost clinical trials and reports of this disease. We emphasize our own treatment paradigm, which is broadly based upon disease subtype, patient fitness, and intent to perform alloHCT. Finally, we highlight recent advances in understanding ATL disease biology and important ongoing clinical trials that we foresee as informative and potentially practice-changing.

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.

Integration of gene co-expression analysis and multi-class SVM specifies the functional players involved in determining the fate of HTLV-1 infection toward the development of cancer (ATLL) or neurological disorder (HAM/TSP).

Human T-cell Leukemia Virus type-1 (HTLV-1) is an oncovirus that may cause two main life-threatening diseases including a cancer type named Adult T-cell Leukemia/Lymphoma (ATLL) and a neurological and immune disturbance known as HTLV-1 Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP). However, a large number of the infected subjects remain as asymptomatic carriers (ACs). There is no comprehensive study that determines which dysregulated genes differentiate the pathogenesis routes toward ATLL or HAM/TSP. Therefore, two main algorithms including weighted gene co-expression analysis (WGCNA) and multi-class support vector machines (SVM) were utilized to find major gene players in each condition. WGCNA was used to find the highly co-regulated genes and multi-class SVM was employed to identify the most important classifier genes. The identified modules from WGCNA were validated in the external datasets. Furthermore, to find specific modules for ATLL and HAM/TSP, the non-preserved modules in another condition were found. In the next step, a model was constructed by multi-class SVM. The results revealed 467, 3249, and 716 classifiers for ACs, ATLL, and HAM/TSP, respectively. Eventually, the common genes between the WGCNA results and classifier genes resulted from multi-class SVM that also determined as differentially expressed genes, were identified. Through these step-wise analyses, PAIP1, BCAS2, COPS2, CTNNB1, FASLG, GTPBP1, HNRNPA1, RBBP6, TOP1, SLC9A1, JMY, PABPC3, and PBX1 were found as the possible critical genes involved in the progression of ATLL. Moreover, FBXO9, ZNF526, ERCC8, WDR5, and XRCC3 were identified as the conceivable major involved genes in the development of HAM/TSP. These genes can be proposed as specific biomarker candidates and therapeutic targets for each disease.

Establishment of an ATLL cell line (YG-PLL) dependent on IL-2 and IL-4, which are replaced by OX40-ligand+ HK with poly-L-histidine and dermatan sulfate.

We established an IL-2 and IL-4 (IL2/4) - dependent adult T-cell leukemia/lymphoma (ATLL) cell line (YG-PLL) by adding poly-L-lysine (PLL) to the culture medium. YG-PLL originates from lymphoma cells and contains a defective HTLV-I proviral genome. Although YG-PLL cannot survive without IL-2/4, the follicular dendritic cell (FDC)-like cell line HK expressing OX40-ligand gene (OX40L+HK) inhibited their death in the presence of soluble neutral polymers. After the prevention of cell death, YG-PLL proliferated on OX40L+HK without IL2/4 in the presence of two kinds of positively or negatively charged polymers. In particular, dermatan sulfate and poly-L-histidine supported growth for more than 4 months. Therefore, the original lymphoma cells proliferated transiently in the presence of IL2/4, and their growth arrest was inhibited by the addition of PLL. Furthermore, YG-PLL lost IL2/4 dependency by the following 3-step procedure: preculture with IL2/4 and neutral polymers, 3-day culture with neutral polymer on OX40L+HK to inhibit cell death, and co-culture with OX40L+HK in the presence of the positively and negatively charged polymers. The extracellular environment made by soluble polymers plays a role in the growth of ATLL in vitro.

Adult T-cell Leukemia-lymphoma with Primary Breast Involvement: A Case Report and Literature Review.

Breast involvement of Adult T-cell leukemia-lymphoma (ATLL) is extremely rare, and the data on the characteristics are limited. We herein describe a 49-year-old woman who presented with skin involvement of ATLL. Positron emission tomography/computed tomography showed bilateral breast lesions. Although the patient once achieved a complete metabolic response, a relapse of her ATLL occurred. The patient received subsequent allogeneic hematopoietic stem cell transplantation (HSCT). To our knowledge, only four cases of ATLL with breast involvement have previously been reported, and the prognoses have generally been poor. Breast lesions of ATLL have aggressive features, and intensive systemic chemotherapy and HSCT are required to improve survival.

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/ß 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.

Clinicopathological analysis of immunohistochemical expression of CD47 and SIRPα in adult T-cell leukemia/lymphoma.

The interaction of CD47 and signal-regulatory protein alpha (SIRPα) induces "don't eat me signal", leading suppression of phagocytosis. This signal can affect the clinical course of malignant disease. Although CD47 and SIRPα expression are associated with clinicopathological features in several neoplasms, the investigation for adult T-cell leukemia/lymphoma (ATLL) has not been well-documented. This study aimed to declare the association between CD47 and SIRPα expression and clinicopathological features in ATLL. We performed immunostaining on 73 biopsy samples and found that CD47 is primarily expressed in tumor cells, while SIRPα is expressed in non-neoplastic stromal cells. CD47 positive cases showed significantly higher FoxP3 (P = .0232) and lower CCR4 (P = .0214). SIRPα positive cases presented significantly better overall survival than SIRPα negative cases (P = .0132). SIRPα positive cases showed significantly HLA class I (P = .0062), HLA class II (P = .0133), microenvironment PD-L1 (miPD-L1) (P = .0032), and FoxP3 (P = .0229) positivity. In univariate analysis, SIRPα expression was significantly related to prognosis (Hazard ratio [HR] 0.470; 95% confidence interval [CI] 0.253-0.870; P = .0167], although multivariate analysis did not show SIPRα as an independent prognostic factor. The expression of SIRPα on stromal cells reflects activated immune surveillance mechanism in tumor microenvironment and induce good prognosis in ATLL. More detailed studies for gene expression or genomic abnormalities will disclose clinical and biological significance of the CD47 and SIRPα in ATLL.

Feed-forward regulatory loop driven by IRF4 and NF-κB in adult T-cell leukemia/lymphoma.

Adult T-cell leukemia/lymphoma (ATL) is a highly aggressive hematological malignancy derived from mature CD4+ T-lymphocytes. Here, we demonstrate the transcriptional regulatory network driven by 2 oncogenic transcription factors, IRF4 and NF-κB, in ATL cells. Gene expression profiling of primary ATL samples demonstrated that the IRF4 gene was more highly expressed in ATL cells than in normal T cells. Chromatin immunoprecipitation sequencing analysis revealed that IRF4-bound regions were more frequently found in super-enhancers than in typical enhancers. NF-κB was found to co-occupy IRF4-bound regulatory elements and formed a coherent feed-forward loop to coordinately regulate genes involved in T-cell functions and development. Importantly, IRF4 and NF-κB regulated several cancer genes associated with super-enhancers in ATL cells, including MYC, CCR4, and BIRC3. Genetic inhibition of BIRC3 induced growth inhibition in ATL cells, implicating its role as a critical effector molecule downstream of the IRF4-NF-κB transcriptional network.

HTLV-positive adult T-cell leukaemia/lymphoma with Epstein-Barr virus and hepatitis B coinfection.

Human T-cell lymphotropic virus (HTLV) is a human oncoretrovirus known to cause adult T-cell leukaemia/lymphoma (ATLL). Coinfection of human T-lymphotropic virus type 1 with Epstein-Barr virus (EBV) results in enhanced expression of the HTLV virus and leads to aggressive organ involvement from T-cell malignancy. It has also been observed that the prevalence of hepatitis B infection has been higher in patients with HTLV ATLL as compared with the general population in certain countries. We describe a case of a 34-year-old man who initially presented with leucocytosis, fatigue and conjunctival erythema. His radiological images revealed significant generalised adenopathy, and his flow cytometry analysis came back positive for CD4-positive T-cell lymphoma. He was subsequently diagnosed with HTLV-positive ATLL. Ultimately the patient was also diagnosed with acute hepatitis B and EBV. We describe a unique case of ATLL with coinfection with two other viruses, the association of which can be of potential prognostic value in guiding the treatment strategies for ATLL.

Flower cells of tropical descent: a challenging case of adult T-cell leukemia/lymphoma.

BACKGROUND: Adult T-cell leukemia/lymphoma (ATLL) is an aggressive disease associated with human T-lymphotropic virus type 1 infection, with a very high prevalence in tropical areas but exceptionally rare in Europe and Western countries. CASE PRESENTATION: We describe a challenging case of ATLL in a young male patient with Brazilian origin and adopted as a child by an Italian family, presenting to our clinic with atypical T-lymphocytosis and life-threatening lung infections. CONCLUSIONS: Diagnosis of ATLL outside of endemic areas can be difficult, requiring a high index of clinical suspicion with careful evaluation of the patient's clinical history. Prognosis is affected by disease stage at presentation and degree of immunosuppression. Few effective treatments are available, although new molecular insights have highlighted the role of host immune response and immune checkpoint blockade inhibitors, given the overexpression of PD-L1 on lymphoma cells and on microenvironment cells.

Mogamulizumab for the Treatment of Adult T-cell Leukemia/Lymphoma.

Mogamulizumab, a defucosylated humanized monoclonal antibody against the C-C chemokine receptor 4 (CCR4), has been approved for the treatment of relapsed adult T-cell leukemia/lymphoma (ATL). Compared with conventional chemotherapy, mogamulizumab monotherapy displayed more efficacy in relapsed ATL, making mogamulizumab a promising therapeutic agent. However, mogamulizumab could increase graft-versus-host disease, resulting in poor survival outcome in the allogenic stem cell transplant (allo-SCT) setting. It is possible that the efficacy of mogamulizumab could be established by the occurrence of skin rashes and/or CCR4 mutational status. Hence, this study reviews the current treatment strategies for patients with ATL and focuses on the safety and efficacy (single-agent and combined with chemotherapy or allo-SCT) of mogamulizumab.

Estimates of the incidence of infection-related cancers in Italy and Italian regions in 2018.

INTRODUCTION: Chronic infections and infestations represent one of the leading causes of cancer. Eleven agents have been categorized by the International Agency for Research on Cancer (IARC) in Group 1, 3 in Group 2A and 4 in Group 2B. We previously estimated that the incidence of cancers associated with infectious agents accounted for the 8.5% of new cancer cases diagnosed in Italy in 2014. METHODS: In the present study we evaluated the incidence of cancer in Italy and in the 20 Italian regions in 2018, based on the data of Cancer Registries, and calculated the fraction attributable to infectious agents. RESULTS: Cancers of infectious origin contributed to the overall burden of cancer in Italy with more than 27,000 yearly cases, the 92% of which was attributable to Helicobacter pylori, human papillomaviruses, and hepatitis B and C viruses. With the exception of papillomavirus-related cancers, the incidence of cancers of infectious origin was higher in males (16,000 cases) than in females (11,000 cases). There were regional and geographical variations of cancers depending on the type of cancer and on the gender. Nevertheless, the overall figures were rather similar, the infection-related cancers accounting for the 7.2, 7.6, and 7.1% of all cancers in Northern, Central, and Southern Italy, respectively. CONCLUSIONS: The estimate of the incidence of cancers attributable to infectious agents in Italy in 2018 (7.3% of all cancer cases) is approximately half of the worldwide burden, which has been estimated by IARC to be the 15.4% of all cancer cases in 2012.

CD30 Characterizes Polylobated Lymphocytes and Disease Progression in HTLV-1-Infected Individuals.

Purpose: Although expression of CD30 is reported in a subset of adult T-cell leukemia/lymphoma cases, its clinicopathologic significance is poorly understood. We aimed to characterize CD30-positive cells and clarify their tumorigenic role in human T-cell lymphotropic virus type 1 (HTLV-1)-infected cells.Experimental Design: CD30-positive peripheral blood mononuclear cells from individuals with differing HTLV-1 disease status were characterized, and the role of CD30 signaling was examined using HTLV-1-infected cell lines and primary cells.Results: CD30-positive cells were detected in all samples examined, and the marker was coexpressed with both CD25 and CD4. This cell population expanded in accordance with disease progression. CD30-positive cells showed polylobation, with some possessing "flower cell" features, active cycling, and hyperploidy. CD30 stimulation of HTLV-1-infected cell lines induced these features and abnormal cell division, with polylobation found to be dependent on the activation of PI3K. The results thus link the expression of CD30, which serves as a marker for HTLV-1 disease status, to an active proliferating cell fraction featuring polylobation and chromosomal aberrations. In addition, brentuximab vedotin, an anti-CD30 monoclonal antibody conjugated with auristatin E, was found to reduce the CD30-positive cell fraction.Conclusions: Our results indicate that CD30-positive cells act as a reservoir for tumorigenic transformation and clonal expansion during HTLV-1 infection. The CD30-positive fraction may thus be a potential molecular target for those with differing HTLV-1 disease status. Clin Cancer Res; 24(21); 5445-57. ©2018 AACR.

Mutational Intratumor Heterogeneity is a Complex and Early Event in the Development of Adult T-cell Leukemia/Lymphoma.

The clonal architecture of tumors plays a vital role in their pathogenesis and invasiveness; however, it is not yet clear how this clonality contributes to different malignancies. In this study we sought to address mutational intratumor heterogeneity (ITH) in adult T-cell leukemia/lymphoma (ATL). ATL is a malignancy with an incompletely understood molecular pathogenesis caused by infection with human T-cell leukemia virus type-1 (HTLV-1). To determine the clonal structure through tumor genetic diversity profiles, we investigated 142 whole-exome sequencing data of tumor and matched normal samples from 71 ATL patients. Based on SciClone analysis, the ATL samples showed a wide spectrum of modes over clonal/subclonal frequencies ranging from one to nine clusters. The average number of clusters was six across samples, but the number of clusters differed among different samples. Of these ATL samples, 94% had more than two clusters. Aggressive ATL cases had slightly more clonal clusters than indolent types, indicating the presence of ITH during earlier stages of disease. The known significantly mutated genes in ATL were frequently clustered together and possibly coexisted in the same clone. IRF4, CCR4, TP53, and PLCG1 mutations were almost clustered in subclones with a moderate variant allele frequency (VAF), whereas HLA-B, CARD11, and NOTCH1 mutations were clustered in subclones with lower VAFs. Taken together, these results show that ATL displays a high degree of ITH and a complex subclonal structure. Our findings suggest that clonal/subclonal architecture might be a useful measure for prognostic purposes and personalized assessment of the therapeutic response.

The HTLV-1 oncoprotein Tax is modified by the ubiquitin related modifier 1 (Urm1).

BACKGROUND: Adult T-cell leukemia/lymphoma (ATL) is an aggressive malignancy secondary to chronic human T-cell lymphotropic virus 1 infection, triggered by the virally encoded oncoprotein Tax. The transforming activity and subcellular localization of Tax is strongly influenced by posttranslational modifications, among which ubiquitylation and SUMOylation have been identified as key regulators of the nuclear/cytoplasmic shuttling of Tax, as well as its ability to activate NF-κB signaling. RESULTS: Adding to the complex posttranslational modification landscape of Tax, we here demonstrate that Tax also interacts with the ubiquitin-related modifier 1 (Urm1). Conjugation of Urm1 to Tax results in a redistribution of Tax to the cytoplasm and major increase in the transcription of the NF-ĸB targets Rantes and interleukin-6. Utilizing a tax-transgenic Drosophila model, we show that the Urm1-dependent subcellular targeting of Tax is evolutionary conserved, and that the presence of Urm1 is strongly correlated with the transcriptional output of Diptericin, an antimicrobial peptide and established downstream target of NF-κB in flies. CONCLUSIONS: These data put forward Urm1 as a novel Tax modifier that modulates its oncogenic activity and hence represents a potential novel target for developing new strategies for treating ATL.