Sunao Atogami

Phenotypic diversity and prognosis of adult T-cell leukemia

We examined phenotypically 107 patients with adult T-cell leukemia (ATL), using a panel of monoclonal antibodies, in order to clarify the occurrence of aberrant phenotypes, and to determine the correlation between phenotypic diversity and prognosis. The incidence of the typical (CD4+.CD8-) phenotype, the double-negative (CD4-.CD8-), the double-positive (CD4+.CD8+), and the CD8-positive (CD4-.CD8+) phenotypes was 81%, 7%, 7%, and 4%, respectively. The median survival time (MST) for all patients was 10.0 months with 17% survival at 2 years. The patients with typical phenotypes had a 10.2 month MST with 20% survival at 2 years, significantly better than the patients with the unusual phenotypes whose MST were 4.9, 7.8, and 2.6 months, respectively, for the double-negative, double-positive, and CD8-positive phenotypes. Lack of antigens reactive with CD2, CD3, CD5, and WT31 monoclonal antibody panels was one factor in bad prognosis, but the presence of CD4 and CD8 antigen abnormalities was much more significant.

Characteristics of chemotherapy-induced clinical remission in long survivors with aggressive adult T-cell leukemia/lymphoma

The acute and lymphoma types of adult T-cell leukemia/lymphoma (ATL) usually have a very poor prognosis, although some patients achieve long survival after chemotherapy. A total of 114 patients with these aggressive types of ATL were newly diagnosed at our institution from 1975 to 1989. By multivariate analysis, poor performance status and high serum creatine levels were associated with shortened survival. With combination chemotherapy, 20 patients achieved complete remission (CR), 53 achieved partial remission (PR) and 35 showed no response. Fifteen of the CR or PR patients survived for more than two years and all other patients survived for less than two years. As compared with short survivors (< 2 years) after remission, long survivors (> or = 2 years) after remission had a higher CR/PR ratio, a longer time until remission and a higher doxorubicin dose to achieve remission. Death due to causes other than the primary disease occurred in 18% of short survivors after remission and in 11.2% of nonresponders, but in none of the long survivors. Long survivors with acute ATL included 6 patients with CR and 5 patients with PR. All four lymphoma type ATL long survivors achieved CR. Monoclonal integration of HTLV-I provirus was detected in the peripheral blood mononuclear cells of all 3 PR long survivors with acute ATL studied, but was not detected in all 4 CR cases studied at remission. The minimum CD4/CD8 ratio of peripheral mononuclear cells at remission was < 1.0 in all acute ATL long survivors with CR, and was > 1.0 in all acute ATL long survivors with PR. Three out of six acute ATL long survivors with CR developed suspected viral infection just before achieving CR. Our findings show that in aggressive ATL the characteristics of remission are heterogeneous even among long survivors.

Frequency of eosinophilia in adult T‐cell leukemia/lymphoma

Cases of adult T‐cell leukemia/lymphoma (ATLL) display several peculiar clinical features, including skin rash, hypercalcemia, and an increase in the absolute neutrophil count. The patients rarely have pronounced eosinophilia. In this study, the eosinophilia observed in lymphoproliferative disorders of 62 patients with ATLL, 27 with T‐cell lymphoma (TL), and 19 with B‐cell lymphoma (BL) was investigated. The incidence of eosinophilia (⩾ 570/μl) was higher in patients with ATLL than in patients with TL or BL. Thirteen patients with ATLL (21.0%), 3 with TL (11.1%), and 2 with BL (10.5%) had eosinophilia. Of these patients, three with ATLL and one with TL who had a pathologic diagnosis of immunoblastic lymphadenopathy (IBL) showed pronounced eosinophilia up to 10,934/μl. Because the number of eosinophils in the peripheral blood of these patients correlated both with the number of ATLL cells and the degree of lymphadenopathy and because this fluctuated with chemotherapy, it seems likely that the secretion of some lymphokines by the lymphoma cells is responsible for the eosinophilia. Cancer 1992; 69:966–971.

Activation of p53 by Nutlin-3a, an antagonist of MDM2, induces apoptosis and cellular senescence in adult T-cell leukemia cells

It has been reported that the induction of cellular senescence through p53 activation is an effective strategy in tumor regression. Unfortunately, however, tumors including adult T-cell leukemia/lymphoma (ATL) have disadvantages such as p53 mutations and a lack of p16INK4a and/or p14ARF. In this study we characterized Nutlin-3a-induced cell death in 16 leukemia/lymphoma cell lines. Eight cell lines, including six ATL-related cell lines, had wild-type p53 and Nutlin-3a-activated p53, and the cell lines underwent apoptosis or cell-cycle arrest, whereas eight cell lines with mutated p53 were resistant. Interestingly, senescence-associated-β-galactosidase (SA-β-gal) staining revealed that only ATL-related cell lines with wild-type p53 showed cellular senescence, although they lack both p16INK4a and p14ARF. These results indicate that cellular senescence is an important event in p53-dependent cell death in ATL cells and is inducible without p16INK4a and p14ARF. Furthermore, knockdown of Tp53-induced glycolysis and apoptosis regulator (TIGAR), a novel target gene of p53, by small interfering RNA(siRNA) indicated its important role in the induction of cellular senescence. As many patients with ATL carry wild-type p53, our study suggests that p53 activation by Nutlin-3a is a promising strategy in ATL. We also found synergism with a combination of Nutlin-3a and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), suggesting the application of Nutlin-3a-based therapy to be broader than expected.

Quantitative characterization and potential function of membrane Fas/APO‐1 (CD95) receptors on leukaemic cells from chronic B and T lymphoid leukaemias

The expression and function of the Fas‐receptor (Fas‐R) were examined in chronic lymphocytic leukaemia (CLL), hairy cell leukaemia‐variant (HCL‐v) and adult T‐cell leukaemia (ATL). The expression of Fas‐R in freshly isolated leukaemic cells was qualitatively and quantitatively different between each disease; faint in B‐CLL, moderate in HCL‐v and strong in ATL. Both full‐length and alternatively spliced truncated forms of Fas mRNA were detected even in CLL B cells with faint to negative Fas‐R, and Fas mRNA was also shown to be capable of increasing in vitro expression, i.e. the message was functional. In contrast, Fas‐R expression on ATL cells was heterogenous and usually intense with a mean density approximately 3‐fold higher than that of normal T cells. Fas‐R was confirmed to have the potential function for anti‐Fas monoclonal antibody‐mediated cell death in vitro in Fas‐R+ ATL cells. The expression level of Fas‐R on the cells was higher in chronic than acute ATL (10360 v 6260 antibody‐binding capacity per cell, mFasABC; P < 0.05) and was inversely correlated with serum LDH activity, suggesting that the strong Fas‐R accounts for the slow progression of chronic ATL and the negative Fas‐R protects from Fas‐mediated cell death. These results show that Fas‐R expression on leukaemic cells is valuable in their characterization and perhaps their function, and may contribute to the progression and immune evasion of malignant clones.

Long-term efficacy of imatinib in a practical setting is correlated with imatinib trough concentration that is influenced by body size: a report by the Nagasaki CML Study Group

Imatinib has dramatically improved long-term survival of chronic myelogenous leukemia (CML) patients. To analyze its efficacy in a practical setting, we registered most of CML patients in Nagasaki Prefecture of Japan. Of these, 73 patients received imatinib as an initial therapy. The overall survival rate of these patients was 88.7% at 6 years, and the cumulative complete cytogenetic response rate was 82.5% at 18 months. These results are comparable with the data of other reports including the IRIS study; however, the administered imatinib dose was smaller in our study than that in other reports. To address these discrepancies, we measured the trough concentration of imatinib among 35 patients. Although 39% of the patients were administered less than 400 mg/day, the trough level was comparable to those of previous reports. The trough level of imatinib showed a significant relationship with its efficacy, and was clearly related to dose of imatinib administrated and dose of imatinib divided by body surface area (BSA). Considering the smaller BSA of Japanese patients as compared to those of foreign origin, the results suggest that a lower dose of imatinib could maintain enough trough level and provided excellent results for the treatment of CML in our registry.

LBH589, a deacetylase inhibitor, induces apoptosis in adult T-cell leukemia/lymphoma cells via activation of a novel RAIDD-caspase-2 pathway

Adult T-cell leukemia/lymphoma (ATLL), an aggressive neoplasm etiologically associated with human T-lymphotropic virus type-1 (HTLV-1), is resistant to treatment. In this study, we examined the effects of a new inhibitor of deacetylase enzymes, LBH589, on ATLL cells. LBH589 effectively induced apoptosis in ATLL-related cell lines and primary ATLL cells and reduced the size of tumors inoculated in SCID mice. Analyses, including with a DNA microarray, revealed that neither death receptors nor p53 pathways contributed to the apoptosis. Instead, LBH589 activated an intrinsic pathway through the activation of caspase-2. Furthermore, small interfering RNA experiments targeting caspase-2, caspase-9, RAIDD, p53-induced protein with a death domain (PIDD) and RIPK1 (RIP) indicated that activation of RAIDD is crucial and an event initiating this pathway. In addition, LBH589 caused a marked decrease in levels of factors involved in ATLL cell proliferation and invasion such as CCR4, IL-2R and HTLV-1 HBZ-SI, a spliced form of the HTLV-1 basic zipper factor HBZ. In conclusion, we showed that LBH589 is a strong inducer of apoptosis in ATLL cells and uncovered a novel apoptotic pathway initiated by activation of RAIDD.

Prognostic significance of the proportion of Ki‐67‐positive cells in adult t‐cell leukemia

The authors examined peripheral blood samples from patients with adult T‐cell leukemia (ATL) using the monoclonal antibody Ki‐67 which detects a nuclear antigen present in actively proliferating cells. In patients with chronic ATL, the percentage of Ki‐67‐positive cells was significantly lower than in acute ATL patients (median values, 3.3% versus 18.9%, P < 0.001). Furthermore, there was a significant inverse correlation between the percentage of Ki‐67‐positive cells and the length of survival (P < 0.001). Serum lactic dehydrogenase (LDH) levels also showed a significant inverse correlation with survival, but this was less strong than that for Ki‐67 (0.01 < P < 0.02). Thus, Ki‐67 positivity appears to indicate the aggressiveness of ATL, and can possibly be used for the clinical classification of ATL patients as well as for the prediction of prognosis.

Soluble and membrane isoforms of Fas/CD95 in fresh adult T-cell leukemia (ATL) cells and ATL-cell lines.

Fas, also designated as Apo‐1 and CD95, is a cell membrane receptor (mFas) involved in apoptotic cell death. A soluble form (sFas) lacking the transmembrane domain due to alternative splicing has been isolated. Abnormal expression of sFas and mFas is likely to be involved in lymphoproliferative disorders and auto‐immune diseases. Adult T‐cell leukemia (ATL) caused by human T‐cell‐leukemia virus type‐1 (HTLV‐1) is well known to be a T‐cell neoplasm with strong mFas expression, suggesting a role of Fas in the pathology of the disease. We examined protein and mRNA expression of the 2 isoforms of Fas in fresh ATL cells and ATL cell lines. In general, mFas was strongly expressed in ATL cells, and sFas levels in sera were high, especially in malignant ATL. However, expression of the isoforms in some cases of ATL varied; there was no mFas expression on the cell surface and sFas levels were high in serum. In contrast, all ATL cell lines examined showed strong mFas expression and scarce production of sFas in the supernatant, corresponding to strong expression of full‐length Fas mRNA and weak to negative expression of alternatively spliced mRNA lacking the transmembrane domain. Our findings indicate that the mode of expression of Fas isoforms in ATL cells is not always homogenous and that Fas may play a role in the malignant behavior and oncogenesis of ATL. Int. J. Cancer 72:128–132, 1997.

Survey of chemokine receptor expression reveals frequent co-expression of skin-homing CCR4 and CCR10 in adult T-cell leukemia/lymphoma.

Adult T-cell leukemia/lymphoma (ATLL) is a malignancy of mature T-cell origin with multi-organ involvement. Because the chemokine receptors play crucial roles in tissue-specific homing of mature lymphocytes, particular chemokine receptors expressed on ATLL cells may be involved in their tissue infiltration. We thus performed a comprehensive survey on the chemokine receptor expression in ATLL. ATLL cells expressed transcripts of CCR1, CCR4, CCR7, CCR8, CCR10 and CXCR4 but hardly expressed those of CCR2, CCR3, CCR5, CCR6, CCR9, CXCR1, CXCR2, CXCR3 and CXCR5. These results were confirmed at the protein level by flow cytometric analysis. Notably, patients who have skin lesions showed significantly higher levels of CCR10 mRNA expression than patients without skin lesions. ATLL cells migrated efficiently to the CCR4 ligand, CCL22, and moderately to the CCR10 ligands, CCL27 and CCL28. Moreover, ATLL skin lesions consistently contained transcripts of CCR10 and its ligands CCL27 and CCL28 besides those of CCR4 and its ligands CCL17 and CCL22 that have been reported previously. Collectively, the frequent co-expression of CCR4 and CCR10, the known pair of skin-homing chemokine receptors, may play an important role in ATLL invasion into the skin.