Long-term maintenance combination chemotherapy with OPEC/MPEC (vincristine or methotrexate, prednisolone, etoposide and cyclophosphamide) or with daily oral etoposide and prednisolone can improve survival and quality of life in adult T-cell leukemia/lymphoma

Therapeutic approaches for HTLV-1-associated adult T-cell leukemia/lymphoma: a comprehensive review

Adult T-cell leukemia/lymphoma (ATLL), an infrequent malignancy resultant from human T-cell lymphotropic virus type I (HTLV-1), exhibits a spectrum of phenotypes, encompassing acute, smoldering, lymphomatous, and chronic variants, each bearing distinct clinical presentations. The preponderant acute manifestation is characterized by hypercalcemia, systemic manifestations, organomegaly, and dermatological eruptions. Conversely, the chronic phenotype is typified by lymphocytosis and/or cutaneous eruptions, while smoldering ATLL assumes an asymptomatic course. Immunocompromise afflicts ATLL patients, heightening their vulnerability to opportunistic infections that frequently intricately intertwine with disease progression. Therefore, an early diagnosis is crucial to manage the disease appropriately. While conventional chemotherapeutic regimens have shown limited success, especially in acute and lymphoma types, recent studies suggest that allogeneic stem cell transplantation might enhance treatment results because it has shown promising outcomes in some patients. Novel therapeutics, such as interferon and monoclonal antibodies, have also shown promise, but more research is needed to confirm their efficacy. Moreover, the identification of biomarkers for ATLL and genetic changes in HTLV-1 infected cells has led to the development of targeted therapies that have shown remarkable success in clinical trials. These targeted therapies have the potential to offer a more personalized approach to the treatment of ATLL. The aim of our review is to elaborate on conventional and novel therapies and the efficiency of mentioned treatments.

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

OPINION STATEMENT

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

How I treat adult T-cell leukemia/lymphoma

Adult T-cell leukemia/lymphoma (ATL) is a highly aggressive T-cell malignancy that arises in a proportion of individuals who are long-term carriers of human T-lymphotropic virus type 1. The median survival of aggressive subtypes is 8 to 10 months; with chemotherapy-based approaches, overall survival has remained largely unchanged in the ∼35 years since ATL was first described. Through the use of 4 representative case studies, we highlight advances in the biological understanding of ATL and the use of novel therapies such as mogamulizumab, as well as how they are best applied to different subtypes of ATL. We discuss the implementation of molecular methods that may guide diagnosis or treatment, although we accept that these are not universally available. In particular, we acknowledge discrepancies in treatment between different countries, reflecting current drug licensing and the difficulties in making treatment decisions in a rare disease, with limited high-quality clinical trial data.

Case Report: Orbital Tumor Revealing Adult T-Cell Leukemia/Lymphoma Associated with Human T-Cell Lymphotropic Virus Type-1

Adult T-cell Leukemia/Lymphoma (ATLL) is a sight- and life-threatening complication of human T-cell lymphotropic virus type 1 (HTLV-1) infection. Ophthalmic manifestations include uveitis, optic nerve oedema, retinal vasculitis, and lymphomatous infiltration. Orbital lesions are rare. We report the case of an orbital tumor revealing systemic ATLL in a 45-year-old Dominican patient who died despite treatment. Apart from late-grade cutaneous T-cell lymphoma, ATLL is the only T-lymphoma to develop in the orbit. Diagnosis is based on serologic evidence of HTLV-1 infection, cytology, and blood sample analysis. Biopsy is deemed necessary. Given the poor prognosis of ATLL and the worldwide presentation of HTLV-1, physicians should consider ATLL in the differential diagnosis of orbital malignant tumor and look for HTLV-1 infection in populations at risk.

Vincristine-cyclophosphamide combination therapy positively affects T-cell subset distribution in systemic lupus erythematosus patients

Background

This study aimed to analyze the T-cell subset distribution in systemic lupus erythematosus (SLE) patients and determine whether vincristine-cyclophosphamide combination therapy can positively affect their T-cell subset distribution to keep the disease in remission.

Material/Methods

Thirteen SLE patients with ‘low activity’ (SLE Disease Activity Index (SLEDAI)≤9), 17 SLE patients with ‘high activity’ (SLEDAI>9), and 15 healthy controls were recruited. SLE patients were treated with vincristine-cyclophosphamide combination therapy. CD3⁺, CD4⁺, and CD8⁺ T-cell percentages were analyzed by flow cytometry at baseline, 3 months, 6 months, 12–24 months, and >24 months.

Results

Significantly negative correlations were observed between the CD3⁺ and CD4⁺ T-cell percentages and SLEDAI scores at baseline (r=−0.471, P=0.015; r=−0.473, P=0.015, respectively). A significantly positive correlation was observed between CD4⁺ T-cell percentage and the complement component C3 at baseline (r=0.612, P=0.002). After 3 months of combination therapy, the CD3⁺ and CD4⁺ T-cell percentages were significantly higher than the high activity baseline (P<0.01, P<0.05, respectively). After 6 months, the CD3⁺, CD4⁺, and CD8⁺ T-cell percentages were all significantly higher than the high activity baseline (P<0.01, P<0.05, P<0.05, respectively).

Conclusions

T-cell subset distributions vary across different levels of SLE disease activity with higher CD3⁺ T-cell and CD4⁺ Th cell percentages favoring lower SLE activity. As CD3⁺ T-cell and CD4⁺ Th cell percentages negatively correlate with SLEDAI, vincristine-cyclophosphamide combination therapy appears to positively affect the T-cell subset distribution in SLE patients to keep the disease in remission by increasing their CD3⁺ T-cell and CD4⁺ Th cell percentages.

Effects of exogenous interleukin-7 on CD8(+) T-cell survival and function in human T-cell lymphotropic virus type 1 infection

Interleukin-7 (IL-7) mediates T-cell homeostasis through its effects on T-cell development, survival and function. In human T-cell lymphotropic virus type 1 (HTLV-1) infection, which is causally implicated in adult T-cell leukemia (ATL), the efficiency with which CD8(+) cytotoxic T-lymphocytes (CTLs) clear HTLV-1-infected cells mediates viral control and may be related to disease progression. We report here that CD127 expression in CD8(+) T-cells is independently related to disease status, and that exogenous IL-7 enhances CD8(+) T-cell survival and clearance of HTLV-1 infected cells in vitro. We conclude that CD127 down-regulation may be associated with disease status in HTLV-1 infection, and propose that exogenous IL-7 may be useful immunotherapy or cytokine adjuvant for an anti-ATL therapeutic vaccine.

Guidelines for the management of mature T-cell and NK-cell neoplasms (excluding cutaneous T-cell lymphoma)

The peripheral T-cell neoplasms are a biologically and clinically heterogeneous group of rare disorders that result from clonal proliferation of mature post-thymic lymphocytes. Natural killer (NK) cell neoplasms are included in this group. The World Health Organization classification of haemopoietic malignancies has divided this group of disorders into those with predominantly leukaemic (disseminated), nodal, extra-nodal or cutaneous presentation. They usually affect adults and are more commonly reported in males than in females. The median age at diagnosis is 61 years with a range of 17-90 years. Although some subtypes may follow a relatively benign protracted course most have an aggressive clinical behaviour and poor prognosis. Excluding anaplastic lymphoma kinase (ALK)-positive anaplastic large cell lymphoma (ALCL), which has a good outcome, 5-year survival for other nodal and extranodal T-cell lymphomas is about 30%. Most patients present with unfavourable international prognostic index scores (>3) and poor performance status. The rarity of these diseases and the lack of randomized trials mean that there is no consensus about optimal therapy for T- and NK-cell neoplasms and recommendations in this guideline are therefore based on small case series, phase II trials and expert opinion.

High prevalence of human T-lymphotropic virus type I carriers among patients with myelodysplastic syndrome refractory anemia with excess of blasts (RAEB), RAEB in transformation and acute promyelocytic leukemia

We examined human T-lymphotropic virus type I (HTLV-I) infection among patients with myelodysplastic syndrome (MDS), refractory anemia with excess of blasts (RAEB)/RAEB in transformation (RAEBt) and acute myelogenous leukemia (AML). The study population consisted of 151 patients: 46 with MDS RAEB/RAEBt and 105 with AML (M1, n = 15; M2, n = 39; M3, n = 18; M4, n = 19; M5, n = 9; M6, n = 3; M7, n = 2). As a reference, we examined 92 patients with refractory anemia (RA) and 405 patients with cardiovascular diseases (CVD). Thirteen patients with RAEB/RAEBt (28.3%), 11 with AML (11.6%), 27 with RA (29.3%), and 45 with CVD (11.0%) were positive for HTLV-I. Seven AML patients with HTLV-I infection had M3 acute promyelocytic leukemia (APL). The prevalences of HTLV-I infection among patients with RAEB/RAEBt (P < 0.001), APL (P = 0.001), and RA (P < 0.001) were significantly higher than that in patients with CVD. The prevalences of HTLV-I infection were still significantly higher in patients with RAEB/RAEBt (P = 0.007), APL (P = 0.017) and RA (P < 0.001) than in those with CVD matched by sex and age. Platelet counts and survival times of RAEB/RAEBt patients with infection were significantly lower than those of patients without infection.

Cyclosporin A inhibits HTLV-I tax expression and shows anti-tumor effects in combination with VP-16

Adult T cell leukemia (ATL) is one of the most refractory malignant hematological diseases. Our previous studies demonstrated HTLV-1Tax protein involvement in clinical manifestation of the aggressive type of ATL and suggested the potential application of agents to inhibit Tax expression for ATL treatment. In the present study, we first examined Tax involvement in the resistance to VP-16-induced apoptosis using four HTLV-1 infected T cell clones and cTax DNA-transfected cells. Next, we examined whether cyclosporin A reduced expression of Tax and its related transfer factors on Western blot and CAT assay. We further investigated whether cyclosporin A in combination with VP-16 can induce apoptosis in HTLV-1 infected T cells. Tax-producing T cells, K3T and F6T, were resistant to VP-16 induced growth inhibition compared with that of the nonproducing cells, S1T and Su9T01. Experiments using S1T and Tax-expressing cDNA-transfected S1T demonstrated Tax-induced resistance to VP-16 induction of apoptosis by DNA ladder formation. Cyclosporin A reduced Tax expression in K3T by Western blot analysis and on CAT assay, showing maximal reduction of 61% and 60% compared to control culture using LTR CAT transfected Jurkat cells and K3T cells, respectively. Cyclosporin A also reduced the nuclear expression of two Tax-related transfer factors, ATF-1 and ATF-2 on Western blot. Cyclosporin A alone did not show any cytotoxicity by itself, but sensitized cells to VP-16 when combined with VP-16. Cyclosporin A may be a useful anti-ATL agent when combined with other anti-cancer agents possibly related to Tax inhibition.

Treatment of adult T-cell leukemia/lymphoma: past, present, and future

Adult T-cell leukemia/lymphoma (ATLL) is a peripheral T-cell malignancy caused by human T-cell lymphotrophic virus type I. Clinical manifestations of ATLL range from smoldering to chronic, lymphoma and acute. Patients with acute and lymphoma type ATLL require therapeutic intervention. Conventional chemotherapeutic regimens used against other malignant lymphoma have been administered to ATLL patients, but the therapeutic outcomes of acute and lymphoma type ATLL remain very poor. Promising results of allogeneic stem cell transplantation (SCT) for ATLL patients have recently been reported and the treatment outcome might be improved for some ATLL patients. Besides conventional chemotherapy and SCT, interferon, zidovudine, arsenic trioxide, targeted therapy against surface molecule on ATLL cells, retinoid derivatives, and bortezomib have been administered to ATLL patients in pilot or phase I/II studies. Further studies are required to confirm the clinical benefits of these novel therapeutics. This article reviews the current status and future directions of ATLL treatment.

Synergistic induction of apoptosis in human leukemia T cells by the Akt inhibitor perifosine and etoposide through activation of intrinsic and Fas-mediated extrinsic cell death pathways

Perifosine is an Akt inhibitor displaying strong antineoplastic effects in human tumor cell lines and is currently being tested in phase II clinical trials for treatment of major human cancers. Several recent studies showed the apoptotic effect of perifosine alone or in combination with other anticancer agents. However, this is the first study describing the effects of combining perifosine with the commonly used chemotherapy drug etoposide in cultured human Jurkat T-leukemia cells. Low concentrations of perifosine (5 micromol/L) induced cell death in a synergistic fashion with etoposide if used simultaneously or immediately following exposure to etoposide (posttreatment). The increase in cell death seems to be due to an inactivation of the Akt survival pathway, where treated cells showed a complete dephosphorylation of Akt. Moreover, combined drug-induced Akt deactivation was associated with a parallel decrease in phosphorylation of FoxO1 transcription factor and in expression of antiapoptotic Bcl-xL. Furthermore, the increase in cell death was associated with a specific activation of the caspase-dependent Fas death receptor pathway. These findings might be useful when designing clinical trials where chemotherapy is combined with perifosine for a potential broad use against hematologic malignancies in which the Akt survival pathway is frequently activated.

Human T cell lymphotropic virus-associated leukemia/lymphoma

PURPOSE OF REVIEW

This article summarizes the current pathophysiologic basis for human T cell lymphotropic virus-associated leukemia/lymphoma as well as past, present, and future therapeutic options.

RECENT FINDINGS

New studies have been published on allogeneic stem cell transplantation, arsenic trioxide, and bortezomib for this condition.

SUMMARY

Studies of the molecular biology of human T cell lymphotropic virus-1-induced T cell leukemia/lymphoma have defined a critical role for oncoprotein, Tax, and activation of nuclear factor kappaB transcription pathways, which have provided rational approaches to improved therapy for T cell leukemia/lymphoma as well as a model for other hematopoietic malignancies characterized by nuclear factor kappaB activation.

Natural history of adult T-cell leukemia/lymphoma and approaches to therapy

After cell-to-cell transmission, HTLV-I increases its viral genome by de novo infection and proliferation of infected cells. Proliferation of infected cells is clonal and persistent in vivo. During the carrier state, infected cells are selected in vivo by the host's immune system, the genetic and epigenetic environment of proviral integration sites, and other factors. In leukemic cells, tax gene expression is frequently impaired by genetic and epigenetic mechanisms. Such loss of Tax expression enables ATL cells to escape the host immune system. On the other hand, ATL cells acquire the ability to proliferate without Tax by intracellular genetic and epigenetic changes. Despite advances in support and the development of novel treatment agents, the prognosis for ATLL remains poor. A number of therapies, however, do appear to improve prognosis compared to CHOP (VEPA). These include interferon-alpha plus zidovudine (probably after 1-2 cycles of CHOP), intensive chemotherapy as in LSG-15 with G-CSF support and Allo-SCT (which includes the potential for cure). Emerging novel approaches include HDAC inhibitors, monoclonal antibodies, and proteasome inhibitors. Comparison between different therapeutic approaches is complicated by the range of natural history of ATLL, different recruitments of naïve-to-therapy, refractory or relapsed patients, and variations in the reporting of outcome that frequently excludes difficult-to-evaluate patients. Moreover, results from relatively small proof-of-principle studies have not been extended with randomized, controlled trials. As a result, currently, there is no clear evidence to support the value of any particular treatment approach over others. To avoid further unnecessary patient suffering and to identify optimal therapy as rapidly as possible, large randomized, controlled trials encompassing multicenter, international collaborations will be necessary.

New therapeutic approaches for adult T-cell leukaemia

Adult T-cell leukaemia or lymphoma is an aggressive malignant disease of mature activated T cells caused by human T-cell lymphotropic virus type I. Patients with this disease have a very poor outlook because of intrinsic chemoresistance and severe immunosuppression. In acute adult T-cell leukaemia, clinical trials in Japan show that although non-targeted combinations of chemotherapy improve response, they do not have a significant effect on complete remission and survival. Antiretroviral therapy with combination zidovudine and interferon alfa, which induces a high rate of complete remission and lengthens survival, should be the first treatment option in acute adult T-cell leukaemia. Patients with adult T-cell lymphoma might benefit from initial aggressive chemotherapy followed by antiretroviral therapy. To prevent relapse in all patients allogeneic bone-marrow transplantation when feasible, or additional targeted therapy, should be mandatory. Based on current pathophysiology, we discuss promising new drugs such as arsenic trioxide, proteasome inhibitors, retinoids, and angiogenesis inhibitors, as well as cellular immunotherapy.

HTLV-I Tax protein inhibits apoptosis induction but not G1 arrest by pyrrolidinedithiocarbamate, an anti-oxidant, in adult T cell leukemia cells

OBJECTIVE

We examined the anti-tumor effect of pyrrolidinedithiocarbamate (PDTC) on HTLV-1-infected T clones and the mechanism of HTLV-1 Tax protein inhibition of PDTC-induced apoptosis.

MATERIALS AND METHODS

Tax-nonproducing clones S1T and Su9T01, Tax-producing clones K3T and F6T, and Tax cDNA stably transfected S1TcTax clones S1TcTax04 and S1TcTax05 were examined for PDTC inhibition of thymidine incorporation and apoptosis induction by ISEL method. In addition, S1TcTax clones were analyzed by DNA histography and DNA fragmentation and also examined for p53, p21, or Bax protein expression by Western blot.

RESULTS

PDTC inhibited thymidine incorporation of all four HTLV-1-infected T cells in a similar dose-dependent manner, but K3T and F6T were more resistant than S1T and Su9T01 in apoptosis induction. S1TcTax clones also showed resistance to PDTC-induced apoptosis as compared to Tax-nonproducing S1T and S1Tneo. DNA histography demonstrated that PDTC induces G1 arrest and apoptosis in S1T and S1Tneo, and that S1TcTax clones are also sensitive to PDTC in G1 arrest but resistant in apoptosis induction. DNA fragmentation also demonstrated ladder formation only in S1Tneo but not in S1TcTax04. Western blots demonstrated higher expression of p53 and p21 proteins in S1Tneo than in S1TcTax04 during whole phase after PDTC stimulation with moderate enhancement in S1Tneo but small in S1TcTax04. Bax protein expression was detected only at early phase in S1Tneo but was not detected in S1TcTax04.

CONCLUSION

These findings suggest that PDTC-induced apoptosis is related with Bax, and that G1 arrest is possibly related with p21. Tax might inhibit apoptosis induction mainly via inhibition of Bax expression preceded at least in part by p53 inhibition.

Current Status of Therapeutic Approaches to Adult T-Cell Leukemia

More than 2 decades have elapsed since the proposal of adult T-cell leukemia (ATL). Since then, the discovery of the etiologic virus, human T-cell leukemia virus type I (HTLV-I), and the establishment of the diagnostic steps of serum test and molecular study have clearly defined ATL as a distinct disease entity. Because conventional chemotherapy, which is active against other lymphoid malignancies, was proven to be ineffective for treating aggressive forms of ATL, ATL has become the target of several clinical studies for the purpose of improving therapeutic outcomes. Combination chemotherapy exclusively designed for ATL has considerably elevated the treatment response rate in ATL patients, but it has not sufficiently extended the median survival time. The introduction of antiviral agents has led to surprising effects for patients with acute ATL. Monoclonal antibodies seem to be promising, especially for patients with chemotherapy-resistant disease. Unfortunately, these approaches did not prove to be sufficient for most patients with ATL to obtain long-term survival. Recent promising reports on allogeneic stem cell transplantation (allo-SCT) for ATL have suggested that allo-SCT could overcome the limitations that other treatment modalities have not surmounted. More efforts are clearly needed to clarify the usefulness of allo-SCT, especially with reduced-intensity conditioning regimens, for ATL patients.

Allogeneic haematopoietic stem cell transplantation for the treatment of adult T-cell leukaemia/lymphoma

The feasibility of allogeneic haematopoietic stem-cell transplantation (allo-HSCT) in 11 patients with adult T-cell leukaemia/lymphoma (ATL) (6 acute, 4 lymphoma, 1 chronic type) was evaluated. The preparative regimens (9 conventional, 2 reduced-intensity) were tolerable. Five patients developed acute graft-versus-host disease (GVHD), and three, extensive chronic GVHD. All 10 patients who survived > 30 d achieved complete remission. Estimated 1-year overall and disease-free survival rates were 53 +/- 30% and 45 +/- 29% respectively. Four patients remain alive and disease-free at a median follow-up of 25 months. The others died of transplantation-related complications. This pilot study suggests that allo-HSCT in ATL should be evaluated further.

Treatment of adult T-cell leukemia-lymphoma by CHOP followed by therapy with antinucleosides, alpha interferon and oral etoposide

Adult T-cell leukemia-lymphoma (ATLL) has a very bad prognosis and remains resistant to conventional therapy. Promising results have been reported with the combination of zidovudine (AZT) and alpha-interferon (IFN).

METHOD

A combination with IFN and antinucleoside [AZT or zalcitabine (ddC)] was applied since 1995 in Martinique (French West Indies). An initial treatment with two cycles of CHOP was added to reduce initial tumoral burden, followed by antiretroviral (ARV) therapy associated with etoposide. We report the characteristics and outcomes of 29 patients diagnosed with an ATLL between 1990 and 1999. The overall median survival was 8 months. A striking improvement of survival was observed when comparing the periods between 1990-1994 and 1995-1999 (17 months versus 3 months, p = 0.004). During the second period, seven patients received a therapy with oral etoposide, antinucleoside and IFN, among which, six patients received an initial induction CHOP chemotherapy. No major toxicity was observed with this strategy. In conclusion, the progression of survival since 1995 suggests that a therapeutic approach combining initial polychemotherapy with CHOP followed by ARV drugs, IFN and oral etoposide is an interesting option in treating patients with ATLL.

Clinical significance of serum neuron-specific enolase in patients with adult T-cell leukemia

The present study examines the clinical significance of serum neuron-specific enolase (NSE) in patients with adult T cell-leukemia (ATL). Serum NSE values were measured using a radioimmunoassay in 35 patients (acute type, n = 15; lymphoma type, n = 10; chronic type, n = 10) and in 7 controls carrying T lymphotropic virus type-1 (HTLV-1). Serum NSE values >10 ng/mL were detected in 9 of 15 patients with acute type (60%), 5 of 10 with lymphoma type (50%), and in one of 10 patients with chronic type (10%) ATL, but in none of the HTLV-1 carriers. Contrary to previous findings demonstrating that 20% of patients with non-Hodgkin's lymphoma (NHL) had positive serum NSE, the frequency of a high NSE value in patients with acute and lymphoma type ATL was much higher (60% and 50%, respectively). The serum NSE value positively correlated with serum thymidine kinase activity (TK) and serum soluble interleukin-2 receptor (sIL-2R) levels (P < 0.04 and P < 0.01, respectively). Serum NSE values at the initial diagnosis were adversely related to overall survival time according to the log-rank test (P < 0.02). Pathological examinations demonstrated that both patients with anaplastic large cell lymphoma type ATL had cytoplasmic NSE and CD30 markers on cell membranes. These findings suggest that serum NSE is partially produced by ATL cells and that ATL tumor cells seem preferentially produce NSE compared with other NHL cells. Serum NSE may be a novel marker of disease aggressiveness as well as a prognostic factor for ATL.

Prevalent loss of mitotic spindle checkpoint in adult T-cell leukemia confers resistance to microtubule inhibitors

Human T-cell leukemia virus type I (HTLV-I) is the causative agent for adult T-cell leukemia (ATL). Molecularly, ATL cells have extensive aneugenic abnormalities that occur, at least in part, from cell cycle dysregulation by the HTLV-I-encoded Tax oncoprotein. Here, we compared six HTLV-I-transformed cells to Jurkat and primary peripheral blood mononuclear cells (PBMC) in their responses to treatment with microtubule inhibitors. We found that both Jurkat and PBMCs arrested efficiently in mitosis when treated with nocodazole. By contrast, all six HTLV-I cells failed to arrest comparably in mitosis, suggesting that ATL cells have a defect in the mitotic spindle assembly checkpoint. Mechanistically, we observed that in HTLV-I Tax-expressing cells human spindle assembly checkpoint factors hsMAD1 and hsMAD2 were mislocated from the nucleus to the cytoplasm. This altered localization of hsMAD1 and hsMAD2 correlated with loss of mitotic checkpoint function and chemoresistance to microtubule inhibitors.

Treatment of adult T-cell leukaemia/lymphoma: current strategy and future perspectives

Human T-cell leukaemia virus type I (HTLV-I) associated adult T-cell leukaemia/lymphoma (ATL) carries a very poor prognosis due to an intrinsic resistance of leukaemic cells to conventional or even high doses of chemotherapy and to an associated severe immunosuppression. Therefore, the potential role of conventional chemotherapy, high dose chemotherapy with autologous or allogeneic bone marrow transplantation remains to be defined. Important progress was achieved in the treatment of ATL with the combination of zidovudine (AZT) and interferon-alpha (IFN) which produces a high response rate in ATL patients with minimal side effects. This treatment seems to prolong the survival of patients much more than intensive chemotherapy. The success of this potentially anti-retroviral approach in the treatment of ATL suggests the existence of continuous HTLV-I replication in vivo. These encouraging results may be improved by the use of higher doses of AZT and IFN combined with other anti-retroviral agents. However, since cure seems still elusive, new therapeutic approaches or new combinations are required. For example, biological mediators such as retinoid acid, which induces apoptosis of ATL cells in vitro, may reduce drug resistance and stimulates immunity to restore anti-tumour activity against ATL cells. Alternatively, immunotherapy with anti-interleukin-2 receptor monoclonal antibodies or injection of cytotoxic T-cells directed against virus antigens could be interesting approaches which may merit further investigations in the near future. Finally, the recent demonstration that the combination of arsenic trioxide (As) and IFN induces a specific degradation of the viral transactivator Tax followed by cell cycle arrest and apoptosis of HTLV-I positive cells may constitute a valuable addition to ATL treatment.

The significance of cytomegalovirus infection over the clinical course of adult T-cell leukemia/lymphoma

The significance of cytomegalovirus (CMV) infections developed over the clinical course of adult T-cell leukemia/lymphoma (ATLL) were evaluated in relation to the patient survival rate, ATL activity and immunocompetent cells. ATLL patients with CMV infections on admission exhibited a poor survival rate, while patients with CMV infections at any time after admission survived longer than those not infected with this virus. ATLL patients who exhibited a numbers of CMV infection on admission showed higher ATL activity and had lower numbers of CD8-positive and CD56-positive cells than those who developed CMV infections at any time after admission. Therefore, it appears likely that patients with CMV infections on admission were in an immunosuppressive state due to aggressive ATL activity.

Effects of Nucleoside Analogs on Native and Site-Directed Mutants of HTLV Type 1 Reverse Transcriptase

A bacterial assay was developed for testing HTLV-1 reverse transcriptase sensitivity to common nucleoside analog inhibitors in an Escherichia coli strain characterized by a temperature sensitive PolI/RecA deletion phenotype. This genetic complementation assay exploits the ability of HTLV-1 reverse transcriptase to functionally replace these missing activities at nonpermissive temperatures. The four inhibitors tested, dideoxyinosine, dideoxyadenosine, deoxythymidine, and didehydrodeoxythymidine are well-known inhibitors of HIV reverse transcriptase. All except dideoxyadenosine showed a strong activity against HTLV-1 reverse transcriptase with IC(50); in the nanomolar range. Sequence alignments were used to identify amino acid residues in HTLV-1 reverse transcriptase, which correspond to those identified as important for drug-resistance in HIV reverse transcriptase. Mutations of some of these HTLV-1 residues altered the IC(50) for the inhibitors as expected, which suggests that these amino acids have a function in HTLV-1 reverse transcriptase similar to that of their homologs in HIV reverse transcriptase. Copyright 2000 Academic Press.

Viral Disease in Hematology

As part of the international outreach of the American Society of Hematology, this review addresses some aspects of the genetics, biology, epidemiology, and clinical relevance of viruses that cause a variety of hematopoietic disorders in human populations. The viruses described here have a different pattern of geographical distribution, and the disease manifestations may vary according to environmental and/or genetic characteristics of the host. Epstein-Barr virus, a linear double-stranded DNA virus (herpesvirus), and the human T-cell leukemia virus, a retrovirus with a single-stranded diploid RNA genome, are associated among other diseases with lymphoma and leukemia/lymphoma, respectively. Both viruses cause a lifelong infection, but only a small percentage of infected individuals develop hematopoietic neoplasms. Epidemiological data suggest that the time of infection may be important in determining disease outcome in both HTLV-I and EBV infection. The pathogenic mechanisms used by these viruses are of most interest since they may recapitulate growth dysregulation steps also occurring in other hematopoietic malignancies.

In Section I Dr. Franchini reviews the biology, genetics and diseases associated with HTLV-I and HTLV-II. In Section II, Dr. Ambinder reviews the biology of EBV infection and its relationship to the pathogenesis of Hodgkin's disease and other malignancies.

In Section III, Dr. Barry reviews the viral hemorrhagic fevers caused by RNA viruses such as Arenaviridae, Bunyaviridae, Filoviridae, and Flaviviridae, which can lead to acute syndromes that can be fatal. However, prompt diagnosis is key for patient management as well as for limiting their spread to others. These syndromes have become the focus of public concern and represent not only a clinical challenge, since in most cases no specific antiviral treatment is available, but also a challenge for future basic research on their biology and pathogenesis since little is known at present.

Viral Disease in Hematology

As part of the international outreach of the American Society of Hematology, this review addresses some aspects of the genetics, biology, epidemiology, and clinical relevance of viruses that cause a variety of hematopoietic disorders in human populations. The viruses described here have a different pattern of geographical distribution, and the disease manifestations may vary according to environmental and/or genetic characteristics of the host. Epstein-Barr virus, a linear double-stranded DNA virus (herpesvirus), and the human T-cell leukemia virus, a retrovirus with a single-stranded diploid RNA genome, are associated among other diseases with lymphoma and leukemia/lymphoma, respectively. Both viruses cause a lifelong infection, but only a small percentage of infected individuals develop hematopoietic neoplasms. Epidemiological data suggest that the time of infection may be important in determining disease outcome in both HTLV-I and EBV infection. The pathogenic mechanisms used by these viruses are of most interest since they may recapitulate growth dysregulation steps also occurring in other hematopoietic malignancies.

In Section I Dr. Franchini reviews the biology, genetics and diseases associated with HTLV-I and HTLV-II. In Section II, Dr. Ambinder reviews the biology of EBV infection and its relationship to the pathogenesis of Hodgkin's disease and other malignancies.

In Section III, Dr. Barry reviews the viral hemorrhagic fevers caused by RNA viruses such as Arenaviridae, Bunyaviridae, Filoviridae, and Flaviviridae, which can lead to acute syndromes that can be fatal. However, prompt diagnosis is key for patient management as well as for limiting their spread to others. These syndromes have become the focus of public concern and represent not only a clinical challenge, since in most cases no specific antiviral treatment is available, but also a challenge for future basic research on their biology and pathogenesis since little is known at present.