Adult T-cell Leukemia/lymphoma Cases Research Articles

<p>Mogamulizumab: a new tool for management of cutaneous T-cell lymphoma</p>

Cutaneous T-cell lymphoma (CTCL) poses unique treatment challenges, given its range of presentations and numerous systemic therapy options. These options often lack comparative evidence or are characterized by low response rates and short remission duration in relapsed/refractory disease. The approval of mogamulizumab, a humanized, glycoengineered IgG1κ monoclonal antibody targeting the chemokine receptor type 4 (CCR4) chemokine receptor, brings a novel tool into the spectrum of treatment options for advanced CTCL and adult T-cell leukemia/lymphoma (ATLL). CCR4 is expressed in almost all cases of ATLL, and in a majority of CTCLs, particularly when blood involvement is present. In a Phase III randomized trial, mogamulizumab was associated with 28% overall response rate among patients with relapsed CTCL, median progression-free survival of 7.7 months, and median duration of remission of 14.1 months. Responses are more frequent among patients with Sézary syndrome and within the blood compartment. Common adverse effects include rash and infusion reactions, which are usually low grade. Sentinel reports indicate that exposure to mogamulizumab may result in severe or refractory graft vs host disease after allogeneic bone marrow transplantation, highlighting the need for vigilance and expert management. Further research may establish incremental efficacy of combining mogamulizumab with cytotoxic or immunomodulatory agents in CTCL, ATLL, and possibly other lymphomas and even solid tumors.

Clinicopathological characteristics of adult T cell leukemia/lymphoma

Objective: To investigate the clinical presentation, clinicopathologic features, diagnosis and differential diagnosis of adult T cell leukemia/lymphoma (ATLL). Methods: Four cases of ATLL from Fujian Cancer Hospital between October 2017 and May 2018 were analyzed using hematoxylin-eosin and immunohistochemical stains and polymerase chain reaction (PCR) for HTLV-1 provirus genes. The relevant literature was reviewed. Results: There were two males and two females, age range 38-80 years. All patients were from coastal cities of Fujian province. Clinical presentations including lymphadenopathy, hepatomegaly and splenomegaly were detected in most patients; skin lesion, hypercalcemia and lymphocytosis were also commonly detected.Histologically, there was diffuse effacement of the normal architecture by tumor cells infiltration. The inflammatory background is usually sparse, with scanty eosinophils. The atypical lymphoid cells were typically medium to large sized with pronounced nuclear pleomorphism, irregular nuclei, chromatin clumping and prominent nucleoli. Blast-like cells with transformed nuclei were present in variable proportions. Giant cells with convoluted or cerebriform nuclear contours may be present. Rare cases may be composed predominantly of anaplastic tumor cells. Characteristic "flower cells" with large multi-lobated nuclei can be seen. The tumor cells were strongly positive for CD2, CD3, CD5, CD4 and CD25, but negative for CD7, CD8 and cytotoxic molecules (including TIA-1, Granzyme B and perforin). In three cases, the large transformed cells were positive for CD30. In one case, the anaplastic large cells were diffusely and strongly positive for CD30. All cases were negative for EBER, but positive for HTLV-1 provirus. Conclusions: ATLL is a rare type of T cell lymphoma with unique clinical and pathological features, and should be distinguished from peripheral T cell lymphoma, NOS, ALK negative anaplastic large cell lymphoma and mycosis fungoides. Hypercalcemia, systemic disease, characteristic "flower cells" and specific immunophenotypic profile of CD3(+), CD4(+), CD25(+), and CD7(-) are highly suggestive. However, ATLL can only be confirmed if the presence of HTLV-1 provirus.

The Rising Number of Adult T Cell Leukemia Lymphoma (ATLL) Cases in Non-Hispanic Blacks and Its Association with Poor Outcomes

IntroductionAdult T-cell leukemia/lymphoma (ATLL) is a rare, aggressive T cell neoplasm associated with a retrovirus human T cell lymphotropic virus (HTLV-1) and carries a dismal prognosis. Within the United States, New York, and Florida see the majority of cases due to the concentration of Caribbean immigrants (Zell, Assal et al. 2016, Malpica, Pimentel et al. 2018). SEER data does not include states like New York and Florida where most cases are seen and therefore a true estimate of the disease burden in this country is not known (Chihara, Ito et al. 2012, Adams, Newcomb et al. 2016).AimWe aim to study the epidemiology and clinical outcomes of ATLL in the United States particularly in the state of New York.MethodsData for New York was obtained from the New York State Cancer Registry (NYSCR). Data were also retrieved from 18 Surveillance, Epidemiology, and End Results (SEER) registries in the United States. Patients with ATLL (HTLV-1 positive) (includes all variants) were categorized using the International Classification of Diseases for Oncology, Third Edition codes ICD-O-3 as 9827/3.Race/ethnicity was categorized as non-Hispanic white, non-Hispanic black, all Hispanic and other/unknown in the NYSCR whereas it was categorized as non-Hispanic white, non-Hispanic black, all Hispanic, non-Hispanic American Indian/Alaska Native, non-Hispanic Asian or Pacific Islander, and non-Hispanic unknown race in SEER.ATLL patients ≥ 15 years of age were identified from 1995 to 2014 in SEER and all ages were included in NYSCR. Survival was estimated from SEER follow-up data with Kaplan Meier survival analysis.For NYSCR mean and median survival time (month) for deceased patients - cases diagnosed through death certificate only were removed. NYSCR does not conduct active patient follow-up and assumes patients are still alive if we didn't find a deathmatch through vital record or National Death Index linkages.ResultsFive hundred and eleven patients with ATLL were identified in SEER. These patients had a median survival of 8 months (m) which was worse than all other subtypes of peripheral T cell lymphoma. (Figure 1) Four hundred and twenty-nine patients with ATLL were identified in NYSCR and these patients had a median survival of 4.5 m. (Figure 2)Over the years from 2000 until 2014 the number of cases diagnosed within SEER registry coverage areas has not changed. In New York state however there has been a doubling in the number of cases diagnosed from 1995 to 2014. (Figure 3A, B)The non-Hispanic black population was diagnosed at a median age of 52.5 in SEER and 54 in NYSCR while the non-Hispanic whites were diagnosed at a median age of 71 in SEER and 64.5 in NYSCR. The Hispanic patients were diagnosed at a median age of 58.5 in NYSCR and 52.5 in SEER. (Figure 4A, B) There was no gender predominance with 50% males in both registries.ATLL patients in SEER were 47.2% non-Hispanic white, 31.7% non-Hispanic black, 9.8% Hispanic and 11.4% other/unknown. There were 5.5% Japanese patients (n=28) diagnosed in SEER. NYSCR had 22.4% non-Hispanic white, 59.4% non-Hispanic black, 15.9% Hispanic and 2.3% other/unknown. (Figure 5A, B)Within SEER registries most cases occurred in New Jersey, California, Connecticut and Georgia. (Figure 6) New York state had a significantly higher number of cases than these states. Seventy four percent cases diagnosed within New York state are diagnosed in New York city and only 26% of cases are diagnosed in upstate New York.Based on reported country of birth within New York state, only 27% of the ATLL cases diagnosed are born in the US whereas 49% are born in the Caribbean (most likely to be from Jamaica, Dominican Republic and Haiti). (Figure 7A, B, C)For SEER and NYSCR the age-adjusted cancer incidence rate by race year and other factors will be presented at the meeting.ConclusionsATLL has a worse prognosis than all other PTCL subtypes. New York State has a high endemicity for ATLL with a rising number of cases. The higher percentage of non-Hispanic black patients in New York compared to the rest of the country is consistent with the diverse racial demographics in this state. Survival varied significantly by race/ethnicity and disparities were evident especially for non-Hispanic blacks who were diagnosed at a younger median age and had a shorter survival. Further research into this aggressive disease is needed to improve outcomes for these patients. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

TET2 Mutation Associated with Organ Infiltrations in ATLL

Introduction: Adult T-cell leukemia/lymphoma (ATLL) is a peripheral T-cell lymphoma that is caused by HTLV-1. The prognosis of acute and lymphomatous variants of ATLL is poor, ranging from 2 weeks to >1 year. Compared to other types of malignant lymphomas, the organ infiltration is frequently observed in ATLL (Yamada et al. Leuk Lymphoma 1997). We previously reported the landscape of genetic mutations in ATLL, and showed that various mutations occurred in the TCR-NFκB pathway in more than 90% of ATLL cases (Kataoka et al. Nat Genet 2015). These somatic mutations are thought to develop ATLL in combination with viral genes such as HTLV-1 bZIP factor (HBZ). Among them, mutations in TET2, an epigenetic regulator, was observed in about 10% of ATLL cases. Higher frequencies inTET2 mutation was reported in other types of peripheral T-cell lymphoma (PTCL); it was observed in about 80% of angioimmunoblastic T-cell lymphoma (AITL) and in about 50% of PTCL, not otherwise specified. In PTCL, it has been reported that additional mutations in lymphoid progenitors derived from TET2 mutated hematopoietic stem cells cause increased cell proliferation and anti-apoptosis, leading to the disease progression. In ATLL, the role of TET2 mutation in disease progression is still unknown. In this study, we investigated the role of TET2 mutation in ATLL using mouse model and acute and lymphomatous variant ATLL cohort.Materials and methods: As an animal model of HTLV-1 infection or ATLL, transgenic mice expressing HBZ under the control of the mouse CD4 promoter (HBZ-Tg) were generated with C57BL/6 background. Heterozygous TET2 knock-down mice (TET2KD) were generated with C57BL/6 background by gene trapping (Tang et al. Transgenic Res 2008; Shide et al. Leukemia 2012). HBZ-Tg/TET2KD compound mice (double mutant) were generated by crossing them. HBZ-Tg, TET2KD, and double mutant mice were investigated by cell counts, organ weight, FACS analysis, pathological analysis, and survival analysis. The relationship between the TET2 mutation status and the clinical feature was investigated using our acute and lymphomatous variant ATLL cohort (n=115).Result: At 12 months, compared to wild type mouse (WT), sporadic splenomegaly and lymphadenopathy were observed in HBZ-Tg. No significant increase was observed in peripheral blood (PB) leukocyte and mononuclear cell (MNC) of BM and spleen, but an increase was observed in the estimated whole body MNC (Femur x 100/6 + spleen) (WT vs. HBZ-Tg; estimated whole body MNC (x106 cells/body), 416±162 vs. 621±147, p=0.01). In FACS analysis, the frequency of CD4+ T-cell was increased in PB, spleen, and BM (WT vs. HBZ-Tg; PB-CD4+ T-cell%, 4.9±0.9 vs. 28.2±22.8, p<0.05; spleen CD4+ T-cell%, 10.3±3.1 vs. 18.2±3.3, P<0.01; BM-CD4+ T-cell%, 1.2±0.6 vs. 2.5±1.1, p<0.05), and the estimated whole body CD4+ T-cell count was also increased (WT vs. HBZ-Tg; CD4+ T-cells (x106 cells/body) 13.6±7.6 vs. 41.9±24.4, p<0.01). In the survival analysis, compared to WT, the shortened overall survival (OS) was observed in HBZ-Tg (median survival time (MST, month), unreached vs. 11.1, p<0.01). In pathological analysis, HBZ-Tg showed increased leukocyte infiltration to various organs such as lung and liver, and the infiltrated cells were mainly composed of T-cells. In the lung, in addition to the cell infiltration, alveolar edema was observed, which was presumed to be the main cause of death.Next, to elucidate the role of TET2 mutation in ATLL, the double mutant was analyzed. At six months, compared to HBZ-Tg, no increase was observed in the number of PB leukocyte, spleen-MNC, and BM-MNC, and also in the frequency and the number of CD4+ T-cells in PB, spleen and BM. However, in pathological and survival analysis, the double mutant showed severe cell infiltration in lung and liver and demonstrated inferior OS (median OS (month), 11.1 vs. 6.0, p<0.05). Further, the double mutant showed increased frequency of CD103 (integrin alpha E), an adhesion molecule, expressing cells (CD4+CD103+% in spleen; 6.7±1.0 vs. 10.9±1.9, p<0.05). In the acute and lymphomatous variant ATLL cohort analysis, genetic and clinical investigation revealed that organ infiltration detectable by imaging studies was frequently observed in TET2 mutated patients (WT-Pt (n=100) vs. TET2 mutated-Pt (n=15); extra nodular lesion, 78/100 vs. 14/15).Conclusion: In both mice model and human cohort, TET2 mutation exacerbated organ infiltration of ATLL cells. DisclosuresNo relevant conflicts of interest to declare.

Genomic alterations using OncoScan in adult T-cell leukemia/lymphoma: A characterization of 69 cases from Peru, the United States, Brazil, and Spain

Aims: Adult T-cell leukemia/lymphoma (ATLL) is an aggressive T-cell lymphoma caused by the HTLV-1 virus with frequent skin involvement. HTLV-1 carriers are found in endemic regions which include south-west Japan, the Caribbean, Central and South America, and Africa. Somatic mutations and copy number variations in ATLL have not been documented in the US, Central and South America. We examined a population of ATLL cases from the US, Central and South America, and Spain using a whole-genome copy number microarray based assay.

Targeting the HTLV-I-Regulated BATF3/IRF4 Transcriptional Network in Adult T Cell Leukemia/Lymphoma

Adult Tcell leukemia/lymphoma (ATLL) is a frequently incurable disease associated with the human lymphotropic virus type I (HTLV-I). RNAi screening of ATLL lines revealed that their proliferation depends on BATF3 and IRF4, which cooperatively drive ATLL-specific gene expression. HBZ, the only HTLV-I encoded transcription factor that is expressed in all ATLL cases, binds to an ATLL-specific BATF3 super-enhancer and thereby regulates the expression of BATF3 and its downstream targets, including MYC. Inhibitors of bromodomain-and-extra-terminal-domain (BET) chromatin proteins collapsed the transcriptional network directed by HBZ and BATF3, and were consequently toxic for ATLL cell lines, patient samples, and xenografts. Our study demonstrates that the HTLV-I oncogenic retrovirus exploits a regulatory module that can be attacked therapeutically with BET inhibitors.

Adult T Cell Leukemia-Lymphoma (ATL): State of the Art.

ATL is a rare and highly aggressive T cell malignancy caused by HTLV-1. We will review the state of the art of ATL epidemiology, pathogenesis, diagnosis, and treatment. Because of population migration, cases of ATL in non-HTLV-1 endemic countries including North America and Europe are increasingly recognized. ATL has diverse clinical manifestations, limited treatment options not widely available globally, and poor prognosis despite therapy. A small subset of patients may achieve prolonged survival with antiviral therapy or allogeneic stem cell transplant. Mogamulizumab, an anti-CCR4 monoclonal antibody, and lenalidomide, an immunomodulatory drug, are approved for ATL in Japan. Molecular studies have identified key alterations in T cell signaling and DNA methylation that may further guide drug development. Patients should be encouraged to enroll in prospective clinical trials when possible. Ongoing, collaborative, international research continues to elucidate disease pathogenesis and contribute to an evolving therapeutic landscape for ATL.

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.

HTLV-1 Alters T Cells for Viral Persistence and Transmission.

Human T-cell leukemia virus type 1 (HTLV-1) was the first retrovirus to be discovered as a causative agent of adult T-cell leukemia-lymphoma (ATL) and chronic inflammatory diseases. Two viral factors, Tax and HTLV-1 bZIP factor (HBZ), are thought to be involved in the leukemogenesis of ATL. Tax expression is frequently lost due to DNA methylation in the promoter region, genetic changes to the tax gene, and deletion of the 5′ long terminal repeat (LTR) in approximately half of all ATL cases. On the other hand, HBZ is expressed in all ATL cases. HBZ is known to function in both protein form and mRNA form, and both forms play an important role in the oncogenic process of HTLV-1. HBZ protein has a variety of functions, including the suppression of apoptosis, the promotion of proliferation, and the impairment of anti-viral activity, through the interaction with several host cellular proteins including p300/CBP, Foxp3, and Foxo3a. These functions dramatically modify the transcriptional profiling of host T cells. HBZ mRNA also promotes T cell proliferation and viability. HBZ changes infected T cells to CCR4+TIGIT+CD4+ effector/memory T cells. This unique immunophenotype enables T cells to migrate into various organs and tissues and to survive in vivo. In this review, we summarize how HBZ hijacks the transcriptional networks and immune systems of host T cells to contribute to HTLV-1 pathogenesis on the basis of recent new findings about HBZ and tax.

Genetic analysis and its clinical implication in adult T-cell leukemia/lymphoma

Adult T-cell leukemia/lymphoma (ATL) is a peripheral T-cell neoplasm with a dismal prognosis. This disease is caused by human T-cell leukemia virus type-1 (HTLV-1) retrovirus. Not only viral proteins, such as Tax and HBZ, but also additional genetic and epigenetic aberrations, including gain-of-function alterations in the components of T-cell receptor/NF-κB pathway or deteriorating alterations responsible for immune surveillance, are essential for ATL development and progression. Furthermore, recent investigation has demonstrated the effects of genetic and epigenetic alterations prevalently identified in ATL on the disease phenotype and its clinical outcomes. Aggressive ATL is associated with an increased burden of genetic and epigenetic abnormalities. Higher frequencies of TP53 and IRF4 mutations and several copy number alterations, including PD-L1 amplifications and CDKN2A deletions, are more predominant in aggressive than indolent diseases. In contrast, STAT3 mutations are more frequent in indolent ATL. Several genetic alterations, such as PD-L1 amplification, can predict the clinical outcomes independent of established clinical factors. Therefore, ATL subtypes can further be subdivided into genetically distinct subgroups with different prognoses. The genetic profiling of ATL cases has revealed its molecular pathology and should contribute to improved prognostication and management of patients with ATL.

Potential anti-lymphoma effect of M-CSFR inhibitor in adult T-cell leukemia/lymphoma.

The c-fms proto-oncogene is also known as macrophage colony stimulating factor receptor (M-CSFR) or colony-stimulating factor-1 receptor (CSF-1R), and is expressed on several types of malignant tumor cells and myeloid cells. In the present study, we found that overexpression of M-CSFR was present in adult T-cell leukemia/lymphoma (ATLL) cases. M-CSFR signaling was associated with lymphoma cell proliferation, and M-CSFR inhibition induced apoptosis in lymphoma cells. The ATLL cell line ATL-T expressed M-CSF/CSF-1 and interleukin (IL)-34, which are both M-CSFR ligands. M-CSF and IL-34 expression was seen in ATLL cases, and co-expression of these ligands was detected in 11 of 13 ATLL cases. M-CSFR inhibition suppressed programmed death-1 and -2 ligand in ATL-T cells and macrophages stimulated with conditioned medium from ATL-T cells. Thus, an M-CSFR inhibitor may be useful as additional therapy against ATLL due to direct and indirect mechanisms.

Targeting the HTLV-I-Regulated BATF3/IRF4 Transcriptional Network in Adult T-Cell Leukemia/Lymphoma

After neonatal HTLV-I infection through breast feeding, approximately 5% of HTLV-I carriers eventually develop Adult T-Cell Leukemia/Lymphoma (ATLL) with a latency of ~50 years, suggesting that acquired genetic and epigenetic changes in cellular genes act in concert with HTLV-I to initiate and maintain oncogenic transformation. We and others have recently utilized next generation sequencing technology to identify mutated genes that could be pivotal in the pathogenesis of ATLL. However, due to the complexity of genomic/epigenetic alteration in the ATLL genome, the identification of indispensable genes for proliferation and/or survival of ATLL cells remains a formidable challenge.To discover essential regulatory networks that are required for the proliferation and survival of ATLL cells, we performed a pooled shRNA screen in 8 ATLL cell lines using a library enriched for shRNAs targeting lymphoid regulatory factors and discovered that two BATF3 shRNAs and one IRF4 shRNA were highly toxic for all ATLL lines, but had little if any effect in other T cell and B cell lines. It is recently shown that a transcriptional complex of Irf4 and Batf binds to AP1-IRF composite (AICE) DNA motifs and plays key roles in the differentiation and function of certain mouse helper T cell subsets. A close paralogue of Batf, Batf3, is an indispensable transcription factor in a mouse dendritic cell subset, but also appears to play a redundant role with Batf in the differentiation of TH2 cells and can substitute for Batf in Batf knockout T cells. Our observations from shRNA screening suggested that IRF4 and BATF3 may cooperate to drive a transcriptional program that is essential for ATLL viability.We next used genome-wide chromatin precipitation (ChIP-seq) to identify the loci that are bound by BATF3 and IRF4. The set of binding peaks and the associated genes in IRF4 and BATF3 ChIP-seq intersected significantly. By integrating the ChIP-seq and gene expression profiling data of shBATF3- and shIRF4-ATLL cells, we defined a set of 68 BATF3-IRF4 direct target genes. Gene set enrichment analysis using gene expression profiling data from primary T cell lymphomas demonstrated that BATF3-IRF4 direct target genes were significantly enriched among genes that are more highly expressed in ATLL than in peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS), suggesting that the BATF3 and IRF4 cooperatively regulate transcription in primary ATLL cells.HBZ is unique among HTLV-I viral proteins in being maintained in expression in all ATLL cases, suggesting that it may help maintain the malignant phenotype. Given that BATF3 and IRF4 are essential regulators in ATLL, we hypothesized possible relationship between HBZ and BATF3-IRF4 complex. We defined HBZ direct target genes by integrating the ChIP-seq and gene expression profiling data of HBZ-knockout ATLL cell lines by CRISPR/Cas9. Notably we discovered that BATF3 was among these. BATF3 mRNA and protein expression decreased following HBZ inactivation.The above considerations suggested that pharmacologic inhibition of the BATF3-IRF4 regulatory network might be a means to attack the HBZ oncogenic program therapeutically. ChIP-seq analysis of two enhancer marks, H3K27ac and BRD4, identified super-enhancers at the BATF3 locus in two ATLL cell lines. The small molecule JQ1 prevents the BET-protein BRD4 from interacting with chromatin, which is required for the function of super-enhancers. JQ1 treatment reduced BATF3 mRNA and protein levels in all ATLL lines tested, correlating with the eviction of BRD4 from the BATF3 super-enhancer. MYC mRNA and protein expression was also broadly downmodulated by JQ1. JQ1 treatment was consistently toxic for all ATLL cell lines tested at dose ranges that killed cell line models of T-ALL and DLBCL, which are known to rely on BET-proteins. In a dose-dependent manner, JQ1 also reduced the viability of primary ATLL samples and downregulated their expression BATF3 and MYC mRNA. Finally, we treated mouse xenograft models of ATLL with the BET-protein inhibitor CPI-203, a JQ1 analog with superior bioavailability in mice. In two different xenograft models, we observed significant tumor regression or growth inhibition, without evidence of systemic toxicity. Our study demonstrates that the HTLV-I virus exploits a regulatory module that can potentially be attacked therapeutically with BET protein inhibitors. DisclosuresYu:Celgene Corporation: Employment.

Genetic alterations in adult T-cell leukemia/lymphoma.

Adult T‐cell leukemia/lymphoma (ATL) is a peripheral T‐cell neoplasm with a dismal prognosis. It is caused by human T‐cell leukemia virus type‐1 (HTLV‐1) retrovirus. A long latency period from HTLV‐1 infection to ATL onset suggests that not only HTLV‐1 proteins, such as Tax and HBZ, but also additional genetic and/or epigenetic events are required for ATL development. Although many studies have demonstrated the biological functions of viral genes, alterations of cellular genes associated with ATL have not been fully investigated. Recently, a large‐scale integrated genetic analysis revealed the entire landscape of somatic aberrations in ATL. This neoplasm is characterized by frequent gain‐of‐function alterations in components of the T‐cell receptor/NF‐κB signaling pathway, including activating mutations in the PLCG1,PRKCB,CARD11 and VAV1 genes, and CTLA4‐CD28 and ICOS‐CD28 fusions. Importantly, molecules associated with immune surveillance, such as HLA‐A/B,CD58 and FAS, are affected recurrently. Among them, one notable lesion occurs as frequent structural variations that truncate the PD‐L1 3′‐untranslated region, leading to its overexpression. Other genetic targets include transcription factors (IRF4,IKZF2, and GATA3) and chemokine receptors (CCR4,CCR7 and GPR183), which are functionally relevant in normal T cells. A substantial proportion of ATL cases show widespread accumulation of repressive epigenetic changes, such as trimethylation of histone H3 lysine 27 and DNA hypermethylation of CpG islands, which coordinately modulate multiple pathways, including Cys2‐His2 zinc finger genes involved in silencing retroelements. Here we review the current understanding of the genetic/epigenetic aberrations in ATL, focusing on their relevance in its molecular pathogenesis.

Abstract 5487: Identification of super-enhancer-associated cancer genes provides novel therapeutic targets in adult T-cell leukemia/lymphoma

Abstract Super-enhancers are often enriched at cancer genes in various malignancies. Identification of such enhancers would pinpoint critical factors that directly contribute to pathogenesis. Adult T-cell leukemia/lymphoma (ATL) is a highly aggressive lymphoproliferative disorder that arises from CD4+ mature T-lymphocytes. A recent genome-wide sequencing study revealed a large number of genetic and chromosomal abnormalities. However, there is still a lack of functional evidence for these genetic abnormalities in ATL pathogenesis due to the large mutational burden and the considerable genetic heterogeneity. Here, we performed super-enhancer profiling combined with gene expression analysis in primary ATL samples and cell lines. Super-enhancers are frequently enriched at genes involved in T-cell activation and T-cell receptor signaling pathway in both ATL and normal CD4+ T-cells, reflecting the origin of leukemia cells. Super-enhancers at the CCR4 gene, a known therapeutic target in ATL, were observed in all ATL cases. Additionally, we identified previously-uncharacterized genes that were highly activated in ATL cells and required for cell growth. A small-molecule inhibitor of CDK7 efficiently downregulated the expression of these genes and inhibited cell growth. Our study provides a novel strategy to identify critical cancer genes in cancer. Note: This abstract was not presented at the meeting. Citation Format: Takaomi Sanda, Regina WJ Wong, Phuong TN Cao, Wei Zhong Leong, Alice WY Yam, Tinghu Zhang, Shinsuke Iida, Takashi Okamoto, Ryuzo Ueda, Nathanael S. Gray, Takashi Ishida. Identification of super-enhancer-associated cancer genes provides novel therapeutic targets in adult T-cell leukemia/lymphoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5487. doi:10.1158/1538-7445.AM2017-5487

Early Onset of HTLV-1 Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP) and Adult T-cell Leukemia/Lymphoma (ATL): Systematic Search and Review.

Human T-cell lymphotropic virus type 1 (HTLV-1) is endemic in some regions and its vertical transmission occurs mainly through breastfeeding. About 10% of carriers develop associated diseases including HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP), adult T-cell leukemia/lymphoma (ATL) and infectious dermatitis associated with HTLV-1 (IDH). We searched for available case reports of early-onset HAM/TSP and ATL to evaluate demographic and disease aspects in infantile-juvenile patients. In the reviewed literature, 27 HAM/TSP and 31 ATL cases were found. In almost all of them, the most likely route of transmission was through breastfeeding. ATL is rarely reported, notwithstanding it may be underestimated because T-cell lymphomas are not investigated for HTLV-1 infection in this age group. IDH was frequently associated with HAM/TSP. The investigation of HTLV-1 infection in pregnant women is an important matter of public health and should be mandatory in endemic countries.

The Impact of a Humanized CCR4 Antibody (Mogamulizumab) on Patients with Aggressive-Type Adult T-Cell Leukemia-Lymphoma Treated with Allogeneic Hematopoietic Stem Cell Transplantation.

Although a humanized CCR4 antibody (mogamulizumab) was reported to be effective for refractory adult T-cell leukemia-lymphoma (ATL), several reports regarding the use of mogamulizumab before allo-hematopoietic stem cell transplantation (HSCT) strongly indicated a high incidence of severe acute graft-versus-host-disease (GVHD) and treatment-related mortality (TRM). We retrospectively analyzed nine aggressive-type ATL patients who underwent allo-HSCT at a single institution in Miyazaki from 2006.1.1 to 2015.7.31. Among nine ATL patients, three had used mogamulizumab before treatment with allo-HSCT because of the poor control of refractory ATL. All three patients were treated with four to eight cycles of mogamulizumab. The interval from last administration of mogamulizumab to allo-HSCT was two to five months. All three patients with prior mogamulizumab treatment developed mild-moderate acute GVHD (grade 2) 28, 34, or 40 days after allo-HSCT. Acute GVHD was controlled by prednisolone treatment. Two patients in complete remission before allo-HSCT exhibited relatively prolonged survival (survival rate, 66%). Moreover, one patient developed human T-cell leukemia virus type 1-associated myelopathy-mimicking myelitis at five months after allo-HSCT. In contrast, two of six ATL patients without a history of mogamulizumab use survived (survival rate 33%). Thus, in cases of mogamulizumab use before treatment with allo-HSCT for refractory ATL, an appropriately long interval from the last administration of mogamulizumab to allo-HSCT may be one of factors to reduce TRM by acute GVHD, and to subsequently enhance graft-versus-tumor effects in ATL cases. Furthermore, caution is needed when administering mogamulizumab before allo-HSCT for severe GVHD and TRM.

Cell adhesion molecule-1 (CADM1) expressed on adult T-cell leukemia/lymphoma cells is not involved in the interaction with macrophages.

Cell adhesion molecule 1 (CADM1) is a cell adhesion molecule that is expressed in brain, liver, lung, testis, and some kinds of cancer cells including adult T-cell leukemia/lymphoma (ATLL). Recent studies have indicated the involvement of CADM1 in cell-cell contact between cytotoxic T-lymphocytes and virus infected cells. We previously reported that cell-cell interaction between lymphoma cells and macrophages induces lymphoma cell proliferation. In the present study, we investigated whether CADM1 is associated with cell-cell interaction between several human lymphoma cell lines and macrophages.CADM1 expression was observed in the ATLL cell lines, ATN-1, ATL-T, and ATL-35T, and in the B cell lymphoma cell lines, TL-1, DAUDI, and SLVL, using western blotting. Significant cell-cell interaction between macrophages and ATN-1, ATL-T, ATL-35T and MT-2, DAUDI, and SLVL cells, as assessed by induction of cell proliferation, was observed. Immunohistochemical analysis of human biopsy samples indicated CADM1 expression in 10 of 14 ATLL cases; however, no case of follicular lymphoma or diffuse large B-cell lymphoma was positive for CADM1. Finally, the interaction of macrophages with cells of the CADM1-negative ED ATLL cell line and CADM1-transfected ED cells was tested. However, significant cell-cell interaction between macrophage and CADM1-transfected ED cells was not observed. We conclude that CADM1 was not associated with cell-cell interaction between lymphoma cells and macrophages, although CADM1 may be a useful marker of ATLL for diagnostic procedures.

Adult T-cell leukemia/lymphoma in South and Central America and the Caribbean: systematic search and review.

Adult T-cell leukemia/lymphoma (ATL) is caused by the human T-cell lymphotropic virus type 1 (HTLV-1) which is endemic in countries of Caribbean and Central and South America. We performed a systematic search and review to identify publications on ATL in these countries to verify if this disease was getting recognition in these regions as well as the characteristics of the observed cases. The median age of 49.4 years was lower than that referred to in Japan. According to our findings in most Brazilian states and in some other countries, ATL is not being recognized and should be strongly considered in the differential diagnosis of T-cell leukemias/lymphomas. Failure to identify these cases may be due to the unsystematic realization of serology for HTLV-1 and phenotypic identification of non-Hodgkin lymphomas that may result from lack of resources. Detection of ATL cases has been more feasible with cooperation from foreign research centers. A huge effort should be made to improve the surveillance system for ATL diagnosis in most of the South- and Central-American and Caribbean countries, and this attitude should be embraced by public organs to support health professionals in this important task.

Quantitative PCR for HTLV-1 provirus in adult T-cell leukemia/lymphoma using paraffin tumor sections.

Detection of HTLV-1 provirus using paraffin tumor sections may assist the diagnosis of adult T-cell leukemia/lymphoma (ATLL). For the detection, non-quantitative PCR assay has been reported, but its usefulness and limitations remain unclear. To our knowledge, quantitative PCR assay using paraffin tumor sections has not been reported. Using paraffin sections from ATLLs and non-ATLL T-cell lymphomas, we first performed non-quantitative PCR for HTLV-1 provirus. Next, we determined tumor ratios and carried out quantitative PCR to obtain provirus copy numbers. The results were analyzed with a simple regression model and a novel criterion, cut-off using 95 % rejection limits. Our quantitative PCR assay showed an excellent association between tumor ratios and the copy numbers (r = 0.89, P < 0.0001). The 95 % rejection limits provided a statistical basis for the range for the determination of HTLV-1 involvement. Its application suggested that results of non-quantitative PCR assay should be interpreted very carefully and that our quantitative PCR assay is useful to estimate the status of HTLV-1 involvement in the tumor cases. In conclusion, our quantitative PCR assay using paraffin tumor sections may be useful for the screening of ATLL cases, especially in HTLV-1 non-endemic areas where easy access to serological testing for HTLV-1 infection is limited.

Smoking is a risk factor for development of adult T-cell leukemia/lymphoma in Japanese human T-cell leukemia virus type-1 carriers.

Adult T-cell leukemia/lymphoma (ATLL) is an aggressive hematological malignancy caused by human T-cell leukemia virus type-1 (HTLV-1); no effective methods have yet been identified to prevent development of ATLL in carriers of HTLV-1. This study investigated the association between cigarette smoking and the risk of ATLL development among Japanese carriers of HTLV-1. This study examined the association between smoking and development of ATLL in a cohort of 1,332 Japanese HTLV-1 carriers aged 40-69years free of ATLL at baseline from two different HTLV-1-endemic areas of Japan. Cox proportional hazards models adjusted for sex, geographic area, age at baseline, and alcohol drinking were used to estimate the effect of cigarette smoking on ATLL development. Between 1993 and 2012, 25 new ATLL cases were identified among these subjects. The overall crude incidence rate for ATLL was 1.08 per 1,000 person-years among HTLV-1 carriers and was higher among male carriers than among female carriers (2.21 vs. 0.74). The risk of ATLL development increased significantly with increasing numbers of cigarettes smoked per day (hazard ratio for every increment of 20 cigarettes, 2.03; 95% confidence interval (CI) 1.13-3.66 overall, 2.07 (95% CI 1.13-3.73) in male carriers). Cigarette smoking may influence ATLL development among HTLV-1 carriers in Japan.