A Retrospective Analysis of Treatment Outcomes in Adult T Cell Leukemia/Lymphoma Patients with Aggressive Disease Treated with or without Allogeneic Stem Cell Transplantation: A Single-Center Experience

Chidamide combined with a modified Bu-Cy conditioning regimen improves survival in patients with T-cell acute lymphoblastic leukemia/lymphoma undergoing allogeneic hematopoietic stem cell transplantation

This study aimed to evaluate the efficacy and safety of chidamide (Chi) combined with a modified Busulfan-Cyclophosphamide (mBuCy) conditioning regimen for T-cell acute lymphoblastic leukemia/lymphoma (T-ALL/LBL) patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). Twenty-two patients received chidamide combined with mBuCy conditioning regimen (Chi group). A matched-pair control (CON) group of 44 patients (matched 1:2) received mBuCy only in the same period. The leukemia-free survival (LFS), overall survival (OS), cumulative incidence of relapse (CIR), and non-relapse-related mortality (NRM) were evaluated. Patients in the Chi group were associated with lower 2-year CIR (19.0 vs. 41.4%, P = 0.030), better 2-year LFS (76.1 vs. 48.1%, P = 0.014), and had no significant difference in 2-year OS (80.5 vs. 66.4%, P = 0.088). Patients with minimal residual disease (MRD) positive before HSCT in the Chi group exhibited an advantage in 2-year LFS and a trend towards better 2-year OS (75.0 vs. 10.2%, P = 0.048; 75.0 vs. 11.4%, P = 0.060, respectively). Multivariable analysis showed that the chidamide intensified regimen was independently associated with better LFS (HR 0.23; 95%CI, 0.08-0.63; P = 0.004), and showed no significant impact with OS for all patients (HR 0.34, 95%CI, 0.11-1.07; P = 0.064). The cumulative incidence rates of grade II-IV aGVHD were similar (36.4 vs. 38.6%, P = 0.858). 20 patients in Chi group evinced an elevation in γ-glutamyltransferase, as compared to the mBuCy group (90.9 vs. 65.9%, P = 0.029). No transplantation-related mortality was documented within the first 100 days after transplantation. The results demonstrate that the chidamide intensified regimen may be an effective and acceptable safety option for T-ALL/LBL undergoing allo-HSCT, and further validation is needed.

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

ABSTRACT

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

Clinical and Public Health Implications of Human T-Lymphotropic Virus Type 1 Infection

Human T-lymphotropic virus type 1 (HTLV-1) is estimated to affect 5 to 10 million people globally and can cause severe and potentially fatal disease, including adult T-cell leukemia/lymphoma (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The burden of HTLV-1 infection appears to be geographically concentrated, with high prevalence in discrete regions and populations. While most high-income countries have introduced HTLV-1 screening of blood donations, few other public health measures have been implemented to prevent infection or its consequences. Recent advocacy from concerned researchers, clinicians, and community members has emphasized the potential for improved prevention and management of HTLV-1 infection. Despite all that has been learned in the 4 decades following the discovery of HTLV-1, gaps in knowledge across clinical and public health aspects persist, impeding optimal control and prevention, as well as the development of policies and guidelines. Awareness of HTLV-1 among health care providers, communities, and affected individuals remains limited, even in countries of endemicity. This review provides a comprehensive overview on HTLV-1 epidemiology and on clinical and public health and highlights key areas for further research and collaboration to advance the health of people with and at risk of HTLV-1 infection.

Allogeneic Stem Cell Transplantation for Adult T-Cell Leukemia/Lymphoma-Romanian Experience

Adult T-cell leukemia/lymphoma (ATLL) is a rare and aggressive mature T-cell malignancy caused by the human T lymphoma virus I (HTLV-I) affecting 3–5% of HTLV-1 carriers and is usually diagnosed in endemic regions. Romania is a region with high prevalence of HTLV-1 infection and ATLL and with low median age at diagnosis for aggressive types. We performed a retrospective analysis of post-transplant outcome in the first Romanian patients with ATLL receiving hematopoietic stem cell allotransplant. The study population included eight patients (three males, five females), with median age of 39.5 (range 26–57), with acute (one case) and lymphoma type (seven cases) that received peripheral stem cells (PBSC) from matched related (MRD) and unrelated donors (MUD) after reduced intensity conditioning. Graft versus host disease (GVHD) developed in six patients. Relapse occurred in four cases (50%) at a median time of 5-months post-transplant. Six patients died: four cases with disease-related deaths and two patients with GVHD-related deaths. The median survival post-transplant was 19.5 months (range 2.3–44.2 months). The post-transplant survival at 1-year was 62.5%, at 2-years 50%, and at 3-years 37.5%. In our opinion allogeneic transplant improves outcome in aggressive type ATLL.

Outcomes of Allogeneic Hematopoietic Stem Cell Transplantation for ATL with HTLV-1 Antibody-Positive Donors

Allogeneic hematopoietic stem cell transplantation (allo-HCT) is the only available curative treatment option for patients with aggressive adult T cell leukemia-lymphoma (ATL). Donor human T cell leukemia virus (HTLV) 1 seropositivity is a critical concern when choosing relative donors, as they are not usually recommended due solely to the occurrence of donor-derived ATL. A previous report suggested that allo-HCT with an HTLV-1-seropositive donor increased ATL-related mortality. We updated the risk assessment for choosing an HTLV-1-seropositive allo-HCT donor for ATL. Our current registry data, which include larger numbers of HTLV-1-seropositive donors and longer observation periods, revealed no significant difference in overall survival (hazard ratio [HR], 0.93; 95% confidence interval [CI], 0.70-1.24; P = .61) or cumulative incidence of either ATL-related (HR, 0.96; 95% CI, 0.64 to 1.45; P = .80) or non-ATL-related mortality (HR, 0.91; 95% CI, 0.61 to 1.37; P = .66). Similarly, when considering only patients with ATL in complete remission, there was no significant difference in overall survival (HR, 1.02; 95% CI, 0.70 to 1.49; P = .91) or cumulative incidence of either ATL-related (HR, 1.20; 95% CI, 0.66 to 2.20; P=0.54) or non-ATL-related mortality (HR, 0.86; 95% CI, 0.52-1.42; P = .66). These data indicate that selecting HTLV-1-seropositive donors might not be contraindicated for patients with ATL receiving allo-HCT if alternative donors are unavailable. Further risk assessment remains to be performed.

Efficacy of Allogeneic Hematopoietic Cell Transplantation in Human T Cell Lymphotropic Virus Type 1-Associated Adult T Cell Leukemia/Lymphoma: Results of a Systematic Review/Meta-Analysis

Human T cell lymphotropic virus type 1 (HTLV1)-associated adult T cell leukemia/lymphoma (ATLL) is an aggressive malignant disorder. Intensive conventional chemotherapy regimens and autologous hematopoietic cell transplantation (HCT) have failed to improve outcomes in ATLL. Allogeneic HCT (allo-HCT) is commonly offered as front-line consolidation despite lack of randomized controlled trials. We performed a comprehensive search of the medical literature using PubMed/Medline, EMBASE, and Cochrane reviews on September 10, 2018. We extracted data on clinical outcomes related to benefits (complete response [CR], overall survival [OS], and progression-free survival [PFS]) and harms (relapse and nonrelapse mortality [NRM]), independently by 2 authors. Our search strategy identified a total of 801 references. Nineteen studies (n = 2446 patients) were included in the systematic review; however, only 18 studies (n = 1767 patients) were included in the meta-analysis. Reduced intensity conditioning regimens were more commonly prescribed (52%). Bone marrow (50%) and peripheral blood (40%) were more frequently used as stem cell source. The pooled post-allografting CR, OS, and PFS rates were 73% (95% confidence interval [CI], 57% to 87%), 40% (95% CI, 33% to 46%), and 37% (95% CI, 27% to 48%), respectively. Pooled relapse and NRM rates were 36% (95% CI, 28% to 43%) and 29% (95% CI, 21% to 37%), respectively. The heterogeneity among the included studies was generally high. These results support the use of allo-HCT as an effective treatment for patients with ATLL, yielding pooled OS rates of 40%, but relapse still occurs in over one-third of cases. Future studies should evaluate strategies to help reduce relapse in patients with ATLL undergoing allo-HCT.

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.

Barriers to Allogeneic Hematopoietic Stem Cell Transplantation for Human T Cell Lymphotropic Virus 1-Associated Adult T Cell Lymphoma-Leukemia in the United States: Experience from a Large Cohort in a Major Tertiary Center

In the United States adult T cell lymphoma-leukemia (ATLL) carries a dismal prognosis and mainly affects immigrants from human T cell lymphotropic virus 1 endemic areas. Allogeneic hematopoietic stem cell transplant (alloHSCT) can be effective and is recommended as an upfront treatment in the National Comprehensive Cancer Network guidelines. We studied the barriers to alloHSCT in one of the largest ATLL populations in the United States. Comprehensive chart and donor registry reviews were conducted for 88 ATLL patients treated at Montefiore Medical Center from 2003 to 2018. Among 49 patients with acute and 32 with lymphomatous subtypes, 48 (59.5%) were ineligible for alloHSCT because of early mortality (52%), loss to follow-up (21%), uninsured status (15%), patient declination (10%), and frailty (2%). Among 28 HLA-typed eligible patients (34.6%), matched related donors were identified for 7 (25%). A matched unrelated donor (MUD) search yielded HLA-matched in 2 patients (9.5%), HLA mismatched in 6 (28.5%), and no options in 13 (62%). Haploidentical donors were identified for 6 patients (46%) with no unrelated options. There were no suitable donors for 7 (25%) alloHSCT-eligible patients. The main limitation for alloHSCT after donor identification was death from progressive disease (82%). AlloHSCT was performed in 10 patients (12.3%) and was associated with better relapse-free survival (26 versus 11 months, P = .04) and overall survival (47 versus 10 months, P = .03). Early mortality and progressive disease are the main barriers to alloHSCT, but poor follow-up, uninsured status, and lack of suitable donor, including haploidentical, are also substantial limitations that might disproportionally affect this vulnerable population. AlloHSCT can achieve long-term remissions, and strategies aiming to overcome these barriers are urgently needed to improve outcomes in ATLL.

Outcome of allogeneic hematopoietic cell transplantation in patients with adult T-cell leukemia

Adult T‐cell leukemia/lymphoma (ATL) is an aggressive peripheral T‐cell neoplasm, and the outcome of patients with ATL after chemotherapy is poor. Allogeneic hematopoietic stem‐cell transplantation (allo‐HSCT) is a curative treatment modality for ATL, and four factors, namely, age > 50 years, male recipient, lack of complete remission at transplantation, and transplantation of cord blood, were previously shown to be associated with poor survival. We retrospectively analyzed the outcome of 21 patients with ATL who had undergone allo‐HSCT at our hospital during a 3‐year period. Of 21 patients, all had at least one of the above risk factors, and 18 had two or more. With a median follow‐up of 19.7 months for living patients, the 1‐ and 2‐year overall survival (OS) rates after transplantation were 34% and 27%, respectively. All relapse/progression events occurred within 1 year after allo‐HSCT, and the cumulative incidence of relapse/progression at 1 year after allo‐HSCT was 46.9%. The 100‐day and 1‐year nonrelapse mortality (NRM) rates were 19% and 42%, respectively. No significant difference in OS was observed between myeloablative and reduced‐intensity conditioning regimens. The 3‐year OS (27%) of ATL patients who received allo‐HSCT and who had at least one adverse factor was somewhat poorer than the 3‐year OS of 33% identified in a nationwide study of allo‐HSCT in ATL patients in Japan. The high relapse/progression and NRM rates are major problems to be solved to achieve better outcome.

Adult T-Cell Leukemia/Lymphoma. Review of the Literature

Adult T-cell Leukemia/Lymphoma (ATLL) is an aggressive neoplasm of T lymphocytes associated with Human T-lymphotropic virus type1 (HTLV-1) infection. HTLV-1 is a public health problem because it is endemic in native groups in Latin America, and its infection leads to several chronic diseases as ATLL. We aimed to review current literature of ATLL in order to consider it as a differential diagnosis in front of patients with compatible symptoms. Prognosis is still poor in aggressive and indolent variants, with survival rates from months to few years. Treatment based on chemotherapy, antiretroviral, and allogenic stem cell transplantation are currently improving survival rates, but with limited results.

Adult T-cell leukemia/lymphoma in the Caribbean cohort is a distinct clinical entity with dismal response to conventional chemotherapy

Adult T-cell leukemia/lymphoma (ATLL) is a rare and aggressive disease caused by human T-cell lymphotropic virus type 1 that predominantly affects Japanese and Caribbean populations. Most studies have focused on Japanese cohorts. We conducted a retrospective analysis of 53 cases of ATLL who presented to our institution between 2003-2014. ATLL in the Caribbean population presents more often as the acute and lymphomatous subtypes, is associated with complex cytogenetics, and has a high rate of CNS involvement. The overall response rate to first-line therapies with anthracycline-based regimens was poor (32%), with a median survival of only 6.9 months. A complete or partial response to first-line regimens was associated with better survival. There was no difference in survival between patients who received chemotherapy alone versus chemotherapy with antiviral agents. Allogeneic transplantation was performed in five patients, two of whom achieved complete remission despite residual or refractory disease. Recipients of allogeneic transplantation had significantly improved overall survival compared to non-transplanted patients. This is the first analysis to describe ATLL pathological features, cytogenetics, and response to standard therapy and transplantation in the Caribbean cohort.

Infection is an Independent Predictor of Death in Diffuse Large B Cell Lymphoma

To identify risk factors for infection in patients with diffuse large B cell lymphoma (DLBCL) undergoing rituximab, cyclophosphamide, vincristine, adriamycin and prednisolone (R-CHOP) treatment. All patients with DLBCL who received R-CHOP from 2004-2014 in a tertiary Australian hospital were identified and information collected from hospital admission data, laboratory results and medical record review. Infection was defined as hospitalisation with an ICD-10-AM diagnostic code for infection. Risk factors for infection and association between infection and survival were modelled using Cox proportional hazards regression. Over the 10-year period there were 325 patients; 191 (58.8%) males, median age 66 years. 206 (63.4%) patients experienced ≥1 infection. Independent predictors of infection were Charlson comorbidity index score (hazard ratio [HR] 3.60, p = 0.002), Eastern Cooperative Oncology Group (ECOG) performance status (HR 2.09 p = <0.001) and neutropenia (HR 2.46, p = <0.001). 99 (31%) patients died. Infection was an independent predictor of survival (HR 3.27, p = <0.001, as were age (HR 2.49, p = 0.001), Charlson comorbidity index (HR 4.34, p = <0.001), ECOG performance status (HR 4.33, p = 0.045) and neutropenia (HR 1.95, p = 0.047). Infections are common and infection itself is an independent predictor of survival. Patients at highest risk of infection and death are those with multiple comorbidities, poor performance status and neutropenia.

Treatment advances and prognosis for patients with adult T-cell leukemia-lymphoma

A classification for adult T-cell leukemia-lymphoma (ATL) based on clinical features was proposed in 1991: acute, lymphoma, chronic, and smoldering types, and their median survival times (MSTs) were reported to be 6.2, 10.2, 24.3 months, and not reached, respectively. Several new therapies for ATL have since been developed, i.e. dose-intensity multi-agent chemotherapies, allogeneic hematopoietic stem cell transplantation (allo-HSCT), monoclonal antibodies, and anti-viral therapy. The monoclonal antibody to CCR4, mogamulizumab, clearly improved response rates in patients with treatment-naïve and relapsed aggressive ATL, and has the potential to provide a survival advantage. The outcomes of allo-HSCT have been reported since the early 2000s. High treatment-related mortality was initially the crucial issue associated with this treatment approach; however, reduced intensity conditioning regimens have decreased the risk of treatment-related mortality. The introduction of allo- HSCT has had a positive impact on the prognosis of and potential curability with treatments for ATL. A meta-analysis of a treatment with interferon-α and zidovudine (IFN/AZT) revealed a survival benefit in patients with the leukemic subtype. A phase 3 study comparing IFN/AZT with watchful waiting in patients with indolent ATL is ongoing in Japan. Several clinical trials on novel agents are currently being conducted, such as the histone deacetylase inhibitors, alemtuzumab, brentuximab vedotin, nivolumab, and an EZH1/2 dual inhibitor.

[Clinical characteristics and prognosis in 12 patients with adult T cell leukemia/lymphoma confirmed by HTLV-1 provirus gene detection]

Objective: To analyze the clinical characteristics and prognosis of adult T cell leukemia/lymphoma (ATLL). Methods: Peripheral blood samples from patients who were suspected as ATLL from March, 2013 to July, 2015, were collected for HTLV-1 provirus genes detection in genomic DNA extraction by PCR. Cases showing positive results were confirmed as ATLL. Clinical and laboratory characteristics, therapeutic outcomes and survival evaluation were collected. Results: 12 out of 23 suspected patients were confirmedly diagnosed as ATLL through HTLV-1 provirus genes detection by PCR. Eight patients were male and four patients were female. Median age was 51 (range 28-66) years old. All of those patients came from coastal cities of Fujian province where a HTLV-1 epidemic area locates. In the subtype classification of these 12 ATLL, 11 patients were classified as acute type and one case as lymphoma type ATLL. As one of the clinical characteristics of ATLL, ' flower cells ', with typical or atypical morphology had been observed in a high rate (81.8%). Clinical symptom such as hepatomegaly, splenomegaly and lymphadenectasis were detected in most of patients, and hypercalcemia and elevated LDH were also noted commonly. The ATLL cells immunophenotype were typical, and the major subtype was CD4+ CD8- type. Confection of hepatitis B virus was detected in a high rate (54.5%). Ten patients received chemotherapy, and 2 cases in complete remission after chemotherapy received allogeneic hematopoietic stem cell transplantation. At the end of the follow-up, 7 cases died, 4 cases survived, 1 case was lost, and the median survival was 2.8 (0.9-10.8) months. We found a case had HTLV-1 provirus negative after transplantation. Conclusion: In the coastal area of Fujian Province, ATLL is not rare. Characteristics of those ATLL are typical. But prognosis is still unsatisfactory.

Human T-cell leukemia virus-associated malignancy

Human T-cell leukemia virus type 1 (HTLV-1) is a tumorigenic delta retrovirus and the causative infectious agent of a non-Hodgkin's peripheral T-cell malignancy called adult T-cell leukemia/lymphoma (ATL). ATL develops in approximately 5% of infected individuals after a significant clinical latency period of several decades. Clinical classifications of ATL include smoldering, chronic, lymphoma, and acute subtypes, with varying median survival ranges of a few months to several years. Depending on the ATL subtype and disease symptoms, treatment options include 'watchful waiting', chemotherapy, antiviral therapy, allogeneic hematopoietic stem cell transplantation (alloHSCT), and targeted therapies. Herein we review the characteristics and development of ATL, as well as current and future treatment options and perspectives.

Striving to cure adult T-cell leukaemia/lymphoma: a role for allogeneic stem cell transplant?

Adult T-cell leukaemia/lymphoma (ATL) is an aggressive HTLV-1-related malignancy, rare outside of regions where the retrovirus is endemic. Although the use of antiviral therapy has improved outcomes, particularly for indolent forms of ATL, response to combination chemotherapy is poor and outcomes for aggressive subtypes remains dismal. Consolidation with allogeneic stem cell transplant (alloSCT) has an increasing role in the management of ATL in eligible patients, offering favourable long-term remission rates. However, relatively high-transplant-related mortality and issues with donor recruitment for certain ethnicities remain problematic. In this review, we discuss the rationale for and issues surrounding alloSCT in ATL in the context of conventional and emerging therapies.

Optimizing Management of Patients with Adult T Cell Leukemia-Lymphoma

Adult T cell leukemia-lymphoma is a rare disease with a high mortality rate, and is challenging for the clinician. Early allogeneic stem cell transplant can confer durable remission. As novel therapeutic agents become available to treat T cell malignancies, it is increasingly important that medical oncologists, hematologists, and hematopathologists recognize and accurately diagnose adult T cell leukemia-lymphoma. There is no uniform standard of treatment of adult T cell leukemia-lymphoma, and clinical trials remain critical to improving outcomes. Here we present one management approach based on the recent advances in treatment for adult T cell leukemia-lymphoma patients.

Complete Remissions of Adult T-cell Leukemia with Anti-CD25 Recombinant Immunotoxin LMB-2 and Chemotherapy to Block Immunogenicity

PURPOSE

Adult T-cell leukemia (ATL) is usually CD25(+) and rapidly fatal. Anti-CD25 recombinant immunotoxin LMB-2 had phase I activity limited by immunogenicity and rapid growth. To prevent antidrug antibodies and leukemic progression between cycles, a phase II trial was performed with LMB-2 after cyclophosphamide and fludarabine.

EXPERIMENTAL DESIGN

ATL patients received cyclophosphamide and fludarabine days 1 to 3 and 2 weeks later began up to 6 cycles at 3-week intervals of cyclophosphamide and fludarabine days 1 to 3 followed by LMB-2 30-40 μg/kg i.v. days 3, 5, and 7. Three different dose levels of cyclophosphamide and fludarabine were used, 20+200 (n = 3), 25+250 (n = 12), and 30+300 mg/m(2) (n = 2).

RESULTS

Of 17 patients enrolled and treated with fludarabine and cyclophosphamide for cycle-1, 15 received subsequent cycle(s) containing LMB-2 and were therefore evaluable for response. Lack of antibody formation permitted retreatment in most patients. Of 10 evaluable leukemic patients receiving 25+250 or 30+300 mg/m(2) of fludarabine and cyclophosphamide, 6 (60%) achieved complete remission (CR) and 2 (20%) partial remission (PR), and all 5 with >25% leukemic cells achieved CR. No responses were achieved in 5 with lymphomatous ATL or lower fludarabine and cyclophosphamide doses. Median CR duration for the 6 CRs was 40 weeks. One is without detectable ATL at 47 months. Toxicity was mostly attributable to fludarabine and cyclophosphamide. Capillary leak from LMB-2 was non-dose limiting. One patient in CR died of a preexisting infection.

CONCLUSIONS

LMB-2, administered with fludarabine and cyclophosphamide to prevent antidrug antibodies and rapid intercycle progression, is highly effective in achieving CR in leukemia ATL. Fludarabine and cyclophosphamide dose/schedule is important for safety and efficacy in this high-risk population.

A new ATL xenograft model and evaluation of pyrrolidine dithiocarbamate as a potential ATL therapeutic agent

Adult T-cell leukemia/lymphoma (ATL) is caused by human T-lymphotrophic virus type 1 infection and is one of the most refractory malignant T-cell lymphomas. Improvement of ATL therapy options requires the establishment of appropriate ATL animal models. In this study, we successfully generated an ATL mouse model by xenotransplantation of primary peripheral blood mononuclear cells (PBMCs) isolated from ATL patients (ATL cells) into nonobese diabetic/severe combined immunodeficiency/Jak3-null mice (NOJ mice). To generate the model, the ATL S1T cell line was subcutaneously injected into mice. Primary ATL cells were then transplanted subcutaneously, intraperitoneally, or intravenously. ATL cells infiltrated multiple organs, and elevated human soluble interleukin 2 receptor (IL-2R) levels were detected in peripheral blood. Injection of one million primary ATL cells was needed for successful engraftment into host mice. Thawed cells, frozen long-term in liquid nitrogen, could also be transplanted; however, more cells were required to achieve similar results. The median mouse survival time was proportional to the number of cells injected. Successful secondary transplantation of ATL cells from one NOJ mouse into another was achieved and confirmed by T-cell receptor analysis. Finally, we examined the effects of the antioxide pyrrolidine dithiocarbamate (PDTC) as an antitumor agent in vivo. PDTC administration inhibited the increase of soluble IL-2R and improved mouse survival, suggesting that this compound has potential as an anti-ATL agent. We demonstrated that ATL cells could be stably xenotransplanted into NOJ mice using primary cells. This model will be useful in the establishment of novel therapies to treat ATL.