Gene expression profiling of p53 and c-myc in HTLV-1 positive blood donors in Congo.

OBJECTIVES: The HTLV-1 infection persists for life, remaining as asymptomatic viral reservoirs in most patients, ensuring the chain of transmission, but around 4% develop adult T-cell leukemia/lymphoma (ATLL). HTLV-1 is an oncogenic retrovirus that transforms CD4+ T lymphocytes and deregulates the lymphoproliferative pathways that contribute to the development of ATLL. To achieve cell transformation, most oncogenic retroviruses use proto-oncogene capture transduction, with proviral integration disrupting the expression of tumor suppressors or proto-oncogenes. THE AIM: We conducted this study on the prevalence of HTLV-1 infection in blood donors to expand the HTLV-1 database, assess the risk of transmission via blood products, as well as evaluate the risk of persistent infection or development of neoplastic diseases in HTLV-1 carriers. MATERIALS AND METHODS: This is a cross-sectional study of blood donors of all categories. For this study, 265 blood donors were recruited at the Centre National de Transfusion Sanguine in Brazzaville. After testing for HTLV-1 antibodies by ELISA, proviral DNA was extracted from all ELISA-positive samples for detection by nested PCR, followed by RT qPCR using specific primers p53 and c-myc for gene expression. RESULTS: 20/265 were positive for anti-HTLV-1 antibody, 5 donors were positive for proviral DNA. The prevalence of HTLV-1 was 1.8%. All HTLV-1-positive donors were male (1.8%), with a positive correlation (p = 0.05); the 1.1% of positive donors were regular, with the majority aged between 31 and 45 years (1.5%), and concubine donors were the most frequent (1.1%). All samples showed normal expression of the p53 and c-myc genes. CONCLUSION: The prevalence, though low, remains a serious problem. No abnormal p53 or c-myc gene expression was detected in HTLV-1-positive donors, which could mean that none of the T lymphocytes in these donors had been transformed by HTLV-1.

Clinical significance of the immunoglobulin G heavy-chain repertoire in peripheral blood mononuclear cells of adult T-cell leukaemia-lymphoma patients receiving mogamulizumab.

'Monitoring of immune responses following mogamulizumab-containing treatment in patients with adult T-cell leukaemia-lymphoma (ATL)' (MIMOGA) is a multicentre prospective clinical study (UMIN000008696). In the MIMOGA study, we found that a lower percentage of CD2- CD19+ B cells in peripheral blood mononuclear cells (PBMC) was a significant unfavourable prognostic factor for overall survival (OS). Accordingly, we then analysed the immunoglobulin G (IgG) heavy-chain repertoire in PBMC by high-throughput sequencing. Of the 101 patients enrolled in the MIMOGA study, for 81 a sufficient amount of PBMC RNA was available for repertoire sequencing analysis. Peripheral IgG B cells in patients with ATL had a restricted repertoire relative to those in healthy individuals. There was a significant positive correlation between the Shannon-Weaver diversity index (SWDI) for the IgG repertoire and proportions of B cells in the PBMC of the patients. Multivariate analysis identified two variables significantly affecting OS: a higher serum soluble interleukin-2 receptor level, and a lower SWDI for the IgG repertoire [hazard ratio, 2·124; 95% confidence interval, 1·114-4·049; n = 44]. The present study documents the importance of humoral immune responses in patients receiving mogamulizumab-containing treatment. Further investigation of strategies to enhance humoral immune responses in patients with ATL is warranted.

Case Report: HTLV-1-Induced Adult T-Cell Leukemia and Tropical Spastic Paresis.

Human T-lymphotropic virus type 1 (HTLV-1) is a retrovirus endemic in many areas around the world. HTLV-1 can induce the development of adult T-cell leukemia (ATL) or myelopathy/tropical spastic paraparesis (HAM/TSP). We report a patient who presented to our outpatient clinic with massive splenomegaly, weight loss, urinary retention, and lower extremity weakness for the previous 3 years. The patient was found to have positive HTLV-1 by ELISA and Western blot from peripheral blood. Evaluation of the spleen demonstrated T-cell large granular lymphocyte leukemia consistent with ATL. In addition to progressive lower extremity weakness, hyperreflexia and clonus, cerebral spinal fluid was positive for HTLV-1 by ELISA and had a reversed CD4-to-CD8 ratio consistent with HAM/TSP. These findings suggest HTLV-1 induced ATL and HAM/TSP presenting simultaneously in the same patient.

Short-term cultured autologous peripheral blood mononuclear cells as a potential immunogen to activate Tax-specific CTL response in adult T-cell leukemia patients.

Activation of CD8+ Tax-specific CTL is a new therapeutic concept for adult T-cell leukemia (ATL) caused by HTLV-1. A recent clinical study of the dendritic cell vaccine pulsed with Tax peptides corresponding to CTL epitopes showed promising outcomes in ATL patients possessing limited human leukocyte antigen (HLA) alleles. In this study, we aimed to develop another immunotherapy to activate Tax-specific CTL without HLA limitation by using patients' own HTLV-1-infected cells as a vaccine. To examine the potential of HTLV-1-infected T-cells to activate CTL via antigen presenting cells, we established a unique co-culture system. We demonstrated that mitomycin C-treated HLA-A2-negative HTLV-1-infected T-cell lines or short-term cultured peripheral blood mononuclear cells (PBMC) derived from ATL patients induced cross-presentation of Tax antigen in co-cultured HLA-A2-positive antigen presenting cells, resulting in activation of HLA-A2-restricted CD8+ Tax-specific CTL. This effect was not inhibited by a reverse transcriptase inhibitor. IL-12 production and CD86 expression were also induced in antigen presenting cells co-cultured with HTLV-1-infected cells at various levels, which were improved by pre-treatment of the infected cells with histone deacetylase inhibitors. Furthermore, monocyte-derived dendritic cells induced from PBMC of a chronic ATL patient produced IL-12 and expressed enhanced levels of CD86 when co-cultured with autologous lymphocytes that had been isolated from the same PBMC and cultured for several days. These findings suggest that short-term cultured autologous PBMC from ATL patients could potentially serve as a vaccine to evoke Tax-specific CTL responses.

Cutaneous plaque in adult T cell leukemia/lymphoma: A case report.

RATIONALE: The rarity of adult T cell leukemia/lymphoma (ATLL) in China, coupled with its clinicopathologic mimicry of primary skin disease, poses a diagnostic challenge. The method of diagnosis and mechanism of immune regulation in ATLL are discussed in the present report. PATIENT CONCERNS: A 51-year-old Chinese man was admitted to the hospital with 2-years history of systemic plaque lesions and 1-year history of left ankle joint pain. DIAGNOSES: The patient was diagnosed with ATLL based on the results of flow cytometry immunophenotype and human T-cell lymphotropic virus type 1 (HTLV-1) serology. INTERVENTIONS: The patient received 3 cycles of cyclophosphamide, epirubicin/ vinorelbine, and dexamethasone (CHOP) chemotherapy. However, he relapsed and did not respond to epirubicin, vindesine, etoposide, dexamethasone (EPOCH) chemotherapy. OUTCOMES: His family discontinued the treatment and opted for hospice care. LESSONS: Patch and plaque ATLL types exhibits a better survival rate, but atypical skin patches delays the diagnosis of ATLL and negatively affects the patient survival. Based on the present findings, we suggest that patients with petal-like nuclear lymphocytes in blood smears, a high CD4: CD8 ratio, and strong CD25 expression should undergo HTLV-1 serology testing.

Prognosis of patients with adult T-cell leukemia/lymphoma in Japan: A nationwide hospital-based study.

Adult T-cell leukemia/lymphoma (ATL) is a mature T-cell neoplasm and is classified into four subtypes (acute, lymphoma, chronic, and smoldering) according to the Shimoyama classification, established in 1991 through several nationwide surveys based on the clinical diversity of patients diagnosed in 1983-1987 in Japan. Thereafter, no such studies have been conducted. Recently, we conducted a nationwide hospital survey using the method of the 1980s studies, collected baseline data on 996 ATL patients diagnosed in 2010-2011 from 126 hospitals, and reported their unique epidemiological characteristics. Here, we report the follow-up results of registered ATL patients with the goal of evaluating current prognoses and treatment modalities as of 2016-2017. Of 770 evaluable patients, 391 (50.8%) had acute-type, 192 (24.9%) had lymphoma-type, 106 (13.8%) had chronic-type, and 81 (10.5%) had smoldering-type ATL. The initial therapy regimens used for acute/lymphoma-type ATL were vincristine, cyclophosphamide, doxorubicin and prednisone, followed by doxorubicin, ranimustine, and prednisone and then by vindesine, etoposide, carboplatin, and prednisone (VCAP-AMP-VECP)-like in 38.5/41.7% and cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP)-like in 14.6/13.7% of patients. Allogeneic hematopoietic stem cell transplantation was used to treat 15.9/10.4% of acute/lymphoma-type ATL patients. The 4-year survival rates (the median survival time, days) for acute-, lymphoma-, unfavorable chronic-, favorable chronic-, and smoldering-type ATL were 16.8% (252), 19.6% (305), 26.6% (572), 62.1% (1937), and 59.8% (1851), respectively. The 4-year survival rates for acute- and lymphoma-type ATL improved compared with those reported in 1991, but those for chronic- and smoldering-type ATL were not. Further efforts are warranted to develop more efficient therapeutic strategies to improve the prognosis of ATL in Japan.

Reduced-intensity haploidentical peripheral blood stem cell transplantation using low-dose thymoglobulin for aggressive adult T cell leukemia/lymphoma patients in non-complete remission.

Haploidentical hematopoietic stem cell transplantation (haplo-HSCT) has been accepted as a treatment option for aggressive (acute or lymphoma type) adult T cell leukemia/lymphoma (ATLL) patients with a poor prognosis, when a suitable HLA-matched donor is not available. However, haplo-HSCT carries a potential risk of treatment-related mortality including severe graft-versus-host disease (GVHD). Therefore, we conducted a prospective pilot study in order to evaluate the efficacy and safety of reduced-intensity haploidentical peripheral blood stem cell transplantation (haplo-PBSCT) with low-dose thymoglobulin (2.5 mg/kg only on day -2), fludarabine, melphalan, and total body irradiation 4 Gy for aggressive ATLL. Three consecutive acute type ATLL patients, who were ineligible for conventional myeloablative conditioning due to advanced age or comorbidities, were enrolled. One patient received pretransplant mogamulizumab therapy. All the patients were not in complete remission (CR) at the time of transplantation. Our transplantation protocol was safely carried out. CR was achieved in all the patients after transplantation. HTLV-I viral loads became undetectable after transplantation. No severe adverse events such as grade III-IV GVHD or viral/fungal diseases were observed. At a follow-up of 2 years, they were still in CR. However, T cell receptor repertoire diversities were low 1 year after transplantation in next-generation sequencing. Our results show encouraging therapeutic benefits of this pilot approach using reduced-intensity haplo-PBSCT with low-dose thymoglobulin for aggressive ATLL patients.

Population Pharmacokinetic Modeling of Mogamulizumab in Adults With Cutaneous T-Cell Lymphoma or Adult T-Cell Lymphoma.

Cutaneous T-cell lymphoma (CTCL) and adult T-cell leukemia/lymphoma (ATL) are rare non-Hodgkin lymphomas commonly expressing C-C chemokine receptor 4 (CCR4). Mogamulizumab is a humanized monoclonal antibody against CCR4 approved in the United States for the treatment of patients with relapsed/refractory mycosis fungoides or Sézary syndrome, the most common forms of CTCL. Pharmacokinetic (PK) and clinical study data from 444 adult patients with ATL or CTCL collected during 6 clinical trials of mogamulizumab were used to construct a population PK model, which was best described by a 2-compartment model with linear clearance. Albumin, aspartate aminotransferase, mild-to-moderate hepatic impairment, and sex were statistically significant predictors of clearance; albumin was also a statistically significant predictor of peripheral volume of distribution; and body surface area was a statistically significant predictor for central volume of distribution. None of the other covariates-for example, age, body weight, body mass index, bilirubin, creatinine clearance, disease type (ATL and CTCL), ATL subtype (acute, lymphoma, and chronic), CTCL subtype (mycosis fungoides and Sézary syndrome), CCR4 expression (status or degree), race (Japanese and non-Japanese), renal impairment (normal, mild, moderate, and severe), or performance status-had a statistically significant impact. Performance of the final population PK model was acceptable. This model will be valuable for guiding further studies of mogamulizumab.

A case series of adult T-cell leukemia-lymphoma, associated with human T-cell leukemia virus type-1, at a single center in a non-viral-endemic metropolitan area.

We examined 13 patients with adult T-cell leukemia-lymphoma (ATL) diagnosed between 2007 and 2018 at a single center in a metropolitan area non-endemic for human T-cell leukemia virus type I (HTLV-1). The median age of the patients (eight male, five female) was 65 years (range, 48-83). The time from onset of symptoms to referral to our center was relatively short (median, 2 months; range, 1-9 months). Upon referral, all patients were suspected to have lymphoma, five were examined for soluble IL-2 receptor and two were examined for anti-HTLV-1 antibody. In ten of the 13 (77%), the patient themselves or their relatives were born in Kyushu. The birth places of the remaining three patients were unknown. Three patients (23%) had family histories of lymphoma. They all exhibited aggressive ATL (five acute, eight lymphoma type); however, the disease status was generally stable, with relatively stable performance status and low scores for prognostic indices. After combination chemotherapy, eight (62%) achieved remission. However, long-term remission was achieved in only one patient with localized lymphoma-type ATL and one young patient after allogeneic hematopoietic stem cell transplantation. In conclusion, at a center in a metropolitan and HTLV-1 non-endemic area in Japan, patients with ATL were relatively young and mainly presented with aggressive subtypes. At initial referral to our center, all 13 patients were suspected of having lymphoma but only two of having ATL. For centers in similar areas of Japan, prompt diagnosis and appropriate treatment of ATL patients will become increasingly necessary following the recent migration of HTLV-1 carriers to non-endemic areas.

Hodgkin-like adult T-cell leukemia/lymphoma that developed during the follow-up of HTLV-1 associated myelopathy/tropical spastic paraparesis.

Hodgkin-like adult T-cell leukemia/lymphoma (ATLL) is a rare variant of ATLL, which represents the early neoplastic phase of ATLL that follows an indolent clinical course compared with typical ATLL. Human T-lymphotropic virus type 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a neurological disorder characterized by the paralysis of lower limbs and urinary disturbance. Although these diseases are caused by HTLV-1 infection, there are no reports describing the coexistence of Hodgkin-like ATLL and HAM/TSP. Here, we report the first case of Hodgkin-like ATLL complicated by HAM/TSP. The patient was a 56-year-old man with right inguinal lymphadenopathy who had been using the neurology outpatient service for 13 years after being diagnosed with HAM/TSP. He was unable to receive intensive chemotherapy or allogeneic stem cell transplantation due to a poor performance status, but his condition was stable for approximately two years.

Association of high levels of plasma OX40 with acute adult T-cell leukemia.

OX40, a member of the tumor necrosis factor receptor (TNFR) superfamily, co-stimulates activated T cells following interaction with its own ligand OX40L. Human T-cell leukemia virus type-1 (HTLV-1) is an etiological agent of adult T-cell leukemia (ATL). ATL cells are known to express cell surface OX40; however, the level of soluble OX40 (sOX40) in blood samples from ATL patients is unknown. Quantitative enzyme-linked immune-sorbent assay (ELISA) showed that sOX40 levels were significantly higher in plasma from acute ATL patients than those from asymptomatic HTLV-1 carriers and healthy donors, and correlated with sCD25 levels and HTLV-1 proviral loads in peripheral blood mononuclear cells (PBMCs). Fresh PBMCs from acute ATL patients showed a higher percentage of OX40-positive cells compared with those from carriers, and shed sOX40 into culture supernatants. Shedding of sOX40 was partially inhibited by a matrix metalloproteinase (MMP) inhibitor, GM6001. A fraction of sOX40 was capable of binding to OX40L. These results suggest that high levels of sOX40 are shed into blood from a large number of ATL cells in acute ATL patients. Thus, abnormally elevated plasma sOX40 levels may be useful as an additional diagnostic marker of acute ATL.

Case of cryptococcal choroiditis in adult with T-cell leukemia/lymphoma.

A rare case of 70-year-old woman with adult T-cell leukemia/lymphoma who developed multifocal choroiditis from a dissemination of Cryptococcus neoformans is reported. Ophthalmologic examination revealed multiple yellowish choroidal lesions in the posterior pole of both eyes. Sequential optical coherence tomographic images disclosed the involvement of the choroid and the consecutive changes in its architecture during the course of treatment. The recognition of these ocular manifestations may be important for the rapid diagnosis of C. nerformans-disseminated diseases. Rapid diagnosis and prompt therapy with intravitreal injection as well as systemic fosfluconazole and liposomal amphotericin B led to clinical improvement of intraocular cryptococcosis.

HTLV-1-host interactions on the development of adult T cell leukemia/lymphoma: virus and host gene expressions.

BACKGROUND: Adult T-cell leukemia/lymphoma (ATLL) is a lymphoproliferative disorder of HTLV-1-host interactions in infected TCD4+ cells. In this study, the HTLV-1 proviral load (PVL) and HBZ as viral elements and AKT1, BAD, FOXP3, RORγt and IFNλ3 as the host factors were investigated. METHODS: The study was conducted in ATLLs, HTLV-1-associated myelopathy/tropical spastic paraparesis patients (HAM/TSPs) and HTLV-1-asympthomatic carriers (ACs). The DNA and mRNA from peripheral blood mononuclear cells were extracted for gene expression assessments via qRT-PCR, TaqMan assay, and then confirmed by western blotting. RESULTS: As it was expected, the HTLV-1-PVL were higher in ATLLs than ACs (P = 0.002) and HAM/TSP (P = 0.041). The HBZ expression in ATLL (101.76 ± 61.3) was radically higher than in ACs (0.12 ± 0.05) and HAM/TSP (0.01 ± 0.1) (P = 0.001). Furthermore, the AKT1 expression in ATLLs (13.52 ± 4.78) was higher than ACs (1.17 ± 0.27) (P = 0.05) and HAM/TSPs (0.72 ± 0.49) (P = 0.008). However, BAD expression in ATLL was slightly higher than ACs and HAM/TSPs and not significant. The FOXP3 in ATLLs (41.02 ± 24.2) was more than ACs (1.44 ± 1) (P = 0.007) and HAM/TSP (0.45 ± 0.15) (P = 0.01). However, RORγt in ATLLs (27.43 ± 14.8) was higher than ACs (1.05 ± 0.32) (P = 0.02) but not HAM/TSPs. Finally, the IFNλ3 expression between ATLLs (31.92 ± 26.02) and ACs (1.46 ± 0.63) (P = 0.01) and ACs and HAM/TSPs (680.62 ± 674.6) (P = 0.02) were statistically different, but not between ATLLs and HAM/TSPs. CONCLUSIONS: The present and our previous study demonstrated that HTLV-1-PVL and HBZ and host AKT1 and Rad 51 are novel candidates for molecular targeting therapy of ATLL. However, high level of RORγt may inhibit Th1 response and complicated in ATLL progressions.

The clinical impact of human T-lymphotrophic virus type 1 (HTLV-1) infection on the development of adult T-cell leukemia-lymphoma (ATL) or HTLV-1-associated myelopathy (HAM) / atypical HAM after allogeneic hematopoietic stem cell transplantation (allo-HSCT) and renal transplantation.

Because there are limited clinical reports on the impact of human T-lymphotropic virus type 1 (HTLV-1) on organ transplantation, its effects on the development of adult T-cell leukemia-lymphoma (ATL), post-transplantation lymphoproliferative disorder (PTLD) and HTLV-1-associated myelopathy (HAM) or atypical HAM after organ transplantation remain unclear.We retrospectively analyzed the impact of HTLV-1 in 54 allogeneic hematopoietic stem cell transplantation (allo-HSCT) cases and 31 renal transplantation cases between January 2006 and December 2016.Among the 54 allo-HSCT cases, nine recipients with ATL tested positive for HTLV-1, and one was found to be an HTLV-1 carrier. All donors tested negative for HTLV-1. Only one HTLV-1 carrier did not present with ATL or HAM development after allo-HSCT. Among nine ATL cases after allo-HSCT, four eventually relapsed due to proliferation of recipient-derived ATL cells. However, in one ATL case, atypical HAM developed rapidly at 5 months after allo-HSCT.Among the 31 renal transplantation cases, all donors tested negative for HTLV-1, and only recipients tested positive. Only one HTLV-1 carrier recipient did not present with ATL or HAM development after renal transplantation. However, one HTLV-1-negative recipient developed PTLD in the brain 10 years after renal transplantation.In clinical practice, careful follow-up of HTLV-1 infected recipients after organ transplantation is important because atypical HAM can develop in ATL patients after allo-HSCT. Furthermore, to clarify the risk of ATL or HAM development in HTLV-1 infected recipients, we prospectively followed up our cohort.

Clinical factors to predict outcome following mogamulizumab in adult T-cell leukemia-lymphoma.

Adult T-cell leukemia-lymphoma (ATL) is a distinct T-cell malignancy caused by human T-cell leukemia virus type-1; the prognosis is very poor. Mogamulizumab (Moga), an antibody drug for CC chemokine receptor type 4, has been introduced for the treatment of ATL. However, the prognosis of relapsed or refractory ATL remains poor and the characteristics of patients who derive clinical benefit from treatment with Moga remain poorly understood. We analyzed the associations of clinical factors with the outcome after Moga treatment. Forty-five patients treated with Moga monotherapy were evaluated. The median age of the patients was 69 years, and 40% were female. The median overall survival (OS) time was 17.6 months and the 2-year OS rate was 43.2%. Number of prior therapies and response to prior therapy were predictive clinical features in univariate analysis for OS. Performance status, corrected serum calcium level, serum lactate dehydrogenase level, Japan Clinical Oncology Group-prognostic index (PI), and simplified ATL-PI at Moga treatment were also associated with the prognosis after Moga monotherapy. Improved understanding of the clinical factors predicting the prognosis after Moga may contribute to improved treatment strategies for ATL.

Low level of serum HDL-cholesterol with increased sIL-2R predicts a poor clinical outcome for patients with malignant lymphoma and adult T-cell leukemia-lymphoma.

Low concentrations of high-density lipoprotein cholesterol (HDL-C) have been reported in patients with hematological malignancies. However, the proof of decreased HDL-C in hematological malignancies and its association with clinical outcomes remain unclear. We analyzed 140 Japanese patients with malignant lymphoma (ML) and adult T-cell leukemia-lymphoma (ATLL). HDL-C, LDL-C and soluble interleukin-2 receptor (sIL-2R) were measured. Treatment decisions were determined with established protocols. HDL-C was 0.98 ±â€¯0.45 mmol/l in patients and 1.51 ±â€¯0.35 mmol/l in controls (P < 0.001). LDL-C was lower in patients than in controls (2.76 ±â€¯0.96, 3.16 ±â€¯0.76 mmol/l, respectively, P < 0.001). HDL-C was the lowest in ATLL (0.81 ±â€¯0.37 mmol/l), modest in non-Hodgkin lymphoma (1.09 ±â€¯0.42 mmol/l) and the highest in Hodgkin's disease (1.14 ±â€¯0.68 mmol/l), (P = 0.0019). Inverse correlation was found between HDL-C and sIL-2R (r = -0.6584, P < 0.001). Categorized patients into 3 subgroups according to HDL-C (<0.52, 0.52-1.02 and ≥1.03 mmol/l), sIL-2R were the highest (median, 36,675; IQR, 17,180-92,600 U/mL) in patients with HDL-C < 0.52 mmol/l, modest (2386, 1324-8340) in HDL-C 0.52-1.02 mmol/l and the lowest (761, 450-1596) in HDL-C ≥ 1.03 mmol/l (P < 0.001). In Cox regression model, the lowest HDL-C levels, <0.52 mmol/l, were associated with poorer clinical outcome and the hazard ratio was 5.73 (95%CI, 3.09-10.50; P < 0.001). In Kaplan-Meier analysis according to HDL-C tertiles (<0.78, 0.78-1.10 and ≥1.11 mmol/l), patients with lowest HDL-C tertile showed inferior overall survival with a median follow-up of 23 months (P < 0.001). We concluded that cytokine-induced low levels of HDL-C in patients with ML and ATLL has independent prognostic significance, and suggesting an early indicator of poorer outcome.

Prognostic index for chronic- and smoldering-type adult T-cell leukemia-lymphoma.

Adult T-cell leukemia-lymphoma (ATL) has been divided into 4 clinical subtypes: acute, lymphoma, chronic, and smoldering. The aim of this study is to develop a novel prognostic index (PI) for chronic and smoldering ATL. We conducted a nationwide retrospective survey on ATL patients, and 248 fully eligible individuals were used in this analysis. In the univariate analysis, sex, performance status, log10 (soluble interleukin-2 receptor [sIL-2R]), neutrophils count, and lymphadenopathy showed values of P < .05 in training samples. A multivariate analysis was performed on these factors, and only log10 (sIL-2R) was identified as an independent prognostic factor in training samples. Using a regression coefficient of this variable, a prognostic model was formulated to identify different levels of risk: indolent ATL-PI (iATL-PI) = 1.51 × log10 (sIL-2R [U/mL]). The values calculated by iATL-PI were divided into 3 groups using a quartile point. In the validation sample, median survival times (MSTs) were 1.6 years, 5.5 years, and not reached for patients in the high-, intermediate-, and low-risk groups, respectively (P < .0001). To make the scoring system clinically practicable, we simplified iATL-PI according to trichotomizing sIL-2R at 1000 and 6000 U/mL, using a quartile point. Patients with more than 6000 U/mL sIL-2R were categorized into the high-risk group, less than and equal to 1000 U/mL into the low-risk group, and the others into the intermediate-risk group, and MSTs were 1.6 years, not reached, and 5.5 years, respectively (P < .0001). iATL-PI has potential as a novel tool for a risk-adapted therapeutic approach.