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 p14 ARF. 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-b-galactosidase (SA-b-gal) staining revealed that only ATL-related cell lines with wild-type p53 showed cellular senescence, although they lack both p16 . 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.

Identification of cytogenetic abnormalities is an important clue for the elucidation of carcinogenesis. However, the cytogenetic and clinical significance of adult T-cell leukemia/lymphoma (ATLL) is still unclear. To address this point, cytogenetic findings in 50 cases of ATLL were correlated with clinical characteristics. Karyotypes showed a high degree of diversity and complexity. Aneuploidy and multiple breaks (at least 6) were observed frequently in acute and lymphoma subtypes of ATLL. Breakpoints tended to cluster at specific chromosomal regions, although characteristic cytogenetic subgroups of abnormalities were not found. Of these, aberrations of chromosomes 1p, 1q, 1q10-21, 10p, 10p13, 12q, 14q

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Fas antigen (Apo-1/CD95) is an apoptosis-signaling cell surface receptor belonging to the tumor necrosis factor receptor superfamily. Adult T cell leukemia (ATL) cells express Fas antigen and show apoptosis after treatment with an anti-Fas monoclonal antibody. We established the ATL cell line KOB, which showed resistance to Fas-mediated apoptosis, and found that KOB expressed two forms of Fas mRNA, the normal form and a truncated form. The truncated transcript lacked 20 base pairs at exon 9, resulting in a frame shift and the generation of a premature stop codon at amino acid 239. The same mutation was detected in primary ascitic cells and peripheral blood cells. The mutation was not detected in lymph node cells, however, although all of the primary ATL cells were of the same clonal origin. A retroviral-mediated gene transfer of the truncated Fas to Jurkat cells rendered the cells resistant to Fas-mediated apoptosis, suggesting a dominant negative interference mechanism. These results indicate that an ATL subclone acquires a Fas mutation in the lymph nodes, enabling the subclone to escape from apoptosis mediated by the Fas/Fas ligand system and proliferate in the body. Mutation of the Fas gene may be one of the mechanisms underlying the progression of ATL.

We examined human T-lymphotropic virus type I (HTLV-I) DNA integration in 68 patients with adult T-cell leukemia/lymphoma (ATL) by Southern blotting using EcoRI, which does not cut within the 9 kb of the genome and probes for pX and gag-pol region of HTLV-I. We detected defective proviral integration as a monoclonal band of various sizes with the pX but not with the gag-pol probe, or a monoclonal band of less than 9 kb with the pX probe, in 20 patients (29.4%). These were designated defective (D) type. With both probes, a single band greater than 9 kb was detected in 34 (50.0%), designated complete (C) type, and two or more bands greater than 9 kb, were designated multiple (M) type, in 14 (20.6%). Advanced age, a high LDH value, and hypercalcemia were more frequent in D type patients. The median survival time (MST) was 6.8, 24.4, and 33.3 months, for D, C, and M types, respectively (log rank P = .006). Among 52 sequentially examined patients, the HTLV-I integration patterns changed in 4 (7.5%). In three of these four, the rearrangements of the T-cell receptor (TCR)b gene concomitantly changed, suggesting the appearance of a new ATL clone. Another patient had the same rearrangement of the TCRb gene, indicating clonal evolution. The HTLV-I integration pattern changed at crisis from indolent to aggressive ATL in three patients. These findings suggested that the HTLV-I integration patterns have clinical implications in ATL pathophysiology. In contrast to the clonal evolution characteristic of the multistep carcinogenesis of most human malignancies, the frequent clonal change of ATL at crisis is a peculiar phenomenon, probably reflecting the emergence of multiple premalignant clones in viral leukemogenesis as suggested in Epstein-Barr virus associated lymphomagenesis in the immunocompromised host.

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.

Background. The authors conducted a survey of a large cohort of patients with adult T‐cell leukemia (ATL) and a group of human T‐cell leukemia virus type 1 (HTLV‐1) carriers to elucidate whether measurements of soluble interleukin‐2 receptor (sIL‐2R) levels are indicative of ATL tumor burden and correlate with clinical progression. Methods. Using a sandwich enzyme immunoassay, the authors determined sIL‐2R in the serum of 135 patients with ATL diagnosed and subclassified according to the Japan Lymphoma Study Group criteria and in the serum of healthy HTLV‐1 seropositive persons. Also included were patients in the preleukemic state of ATL (pre‐ATL), which is characterized by only slight blood changes but does not fit the diagnostic criteria of ATL. In the five subjects who finally advanced to overt ATL, the authors prospectively performed serial measurements of the receptor. Results. Serial measurements of sIL‐2R levels taken until overt ATL developed showed that these levels in the initial samples were higher than those of control subjects, even when subjects were asymptomatic or in the pre‐ATL state. The serial levels of the five subjects gradually increased despite being in a clinically stable condition, finally reaching markedly high levels at the time ATL became overt. The mean sIL‐2R levels of the smoldering, chronic, acute, and lymphoma subtypes of ATL were 1680 U/ml, 6680 U/ml, 45,940 U/ml, and 34,620 U/ml, respectively (P > 0.01). The sIL‐2R levels of each subtype at the time of diagnosis were more correlated with tumor burden, malignant behavior, and prognosis than lactate dehydrogenase (LDH) levels. In the low, moderate, and high sIL‐2R subgroups, the median survival time and percent survival probability at 2 years was 30.2 months (46.0%), 16.5 months (25.0%), and 7.7 months (15.3%), respectively. Conclusions. Serial measurements of sIL‐2R levels are of clinical importance because changes of the levels correlate with disease progression, especially in early phase of ATL. The data suggest that sIL‐2R may be more useful than LDH. In addition, emphasis may be placed on sIL‐2R as an indicator of ATL progression status and prognosis for survival. The value of this marker in clinical practice should be confirmed prospectively. Cancer 1994; 73:2753–8.