Classical and molecular cytogenetic abnormalities and outcome of childhood acute myeloid leukaemia: report from a referral centre in Israel

The incidence of cytogenetic abnormalities in childhood de novo acute myeloid leukaemia (AML) and its prognostic significance was assessed in an Israeli paediatric referral centre. Cytogenetic analysis was successful in 86 of 97 children (< 20 years of age) diagnosed between 1988 and 2002 with de novo AML. Fluorescence in situ hybridization analysis detected new information in 11 of them, leading to reassignment in cytogenetic group classification. The incidence of the various cytogenetic subgroups was as follows: normal - 9%; t(11q23) - 22%; t(8;21) - 13%; t(15;17) - 8%; inv(16) - 3.4%; abn(3q) - 4.6%; 7/7q-(sole or main) - 5.8%; del(9q)(sole) and +21(sole) - 4.6% each; t(8;16) - 2.3%; t(6;9), t(1;22), +8(sole) - 1.1% each; and miscellaneous - 18%. The overall survival (OS) and event-free survival (EFS) (4 years) for 94 patients treated with the modified Berlin-Frankfürt-Münster (BFM) AML protocols (non-irradiated) were 59.9% (SE = 5%) and 55.7% (SE = 5%), respectively, and for the favourable t(8;21), t(15;17) and inv(16), OS was 60% (SE = 15%), 83% (SE = 15%) and 100% respectively. For the normal group it was 62% (SE = 17%), miscellaneous 64% (SE = 12%), t(11q23) 44.6% (SE = 11%) and of the -7/7q-, del(9q)(sole) or t(6;9), none had survived at 4 years. The incidence of cytogenetic subgroups in the Israeli childhood AML population and their outcome were similar to other recently reported paediatric series. Cytogenetic abnormalities still carry clinical relevance for treatment stratification in the context of modern chemotherapy.     

The significance of trisomy 8 in de novo acute myeloid leukaemia: the accompanying chromosome aberrations determine the prognosis

Trisomy 8 is the most frequent numerical chromosome aberration in acute myeloid leukaemia (AML). It occurs either as the sole anomaly or together with other clonal chromosome aberrations. We investigated whether accompanying chromosome anomalies influence the clinical outcome in patients with trisomy 8 and de novo AML. Since 1986, in 713 AML cases treated according to the protocols of the German AMLCG trials, chromosome analyses have been successfully performed. The overall incidence of trisomy 8 was 7.6%. Complete clinical follow-up data were available for 51 patients who were divided into three different categories: group 1: trisomy 8 as the sole cytogenetic anomaly (n = 20); group 2: trisomy 8 in addition to favourable chromosome aberrations (t(8;21)(q22;q22), t(15;17)(q22;q21), inv(16)(p13q22)) (n = 10); and group 3: trisomy 8 accompanied by other anomalies, in most cases of complex type (n = 21). Complete remission (CR) rates were 70%, 90% and 67% for groups 1, 2 and 3, respectively. Event-free survival (EFS) at 3 years differed significantly between patients with trisomy 8 only (37.5%), patients with trisomy 8 in combination with favourable aberrations (55.0%) and patients with trisomy 8 and other accompanying anomalies, mostly complex chromosome aberrations (9.0%) (group 1 v group 2: P = 0.12; group 1 v group 3: P = 0.005; group 2 v group 3: P = 0.05). In this study patients with +8 as the sole cytogenetic anomaly had an intermediate prognosis, patients with +8 in addition to favourable chromosome aberrations maintained a good clinical outcome, and patients with +8 in combination with other abnormalities showed the worst prognosis.     

The significance of trisomy 8 in de novo acute myeloid leukaemia: the accompanying chromosome aberrations determine the prognosis

Trisomy 8 is the most frequent numerical chromosome aberration in acute myeloid leukaemia (AML). It occurs either as the sole anomaly or together with other clonal chromosome aberrations. We investigated whether accompanying chromosome anomalies influence the clinical outcome in patients with trisomy 8 and de novo AML. Since 1986, in 713 AML cases treated according to the protocols of the German AMLCG trials, chromosome analyses have been successfully performed. The overall incidence of trisomy 8 was 7.6%. Complete clinical follow-up data were available for 51 patients who were divided into three different categories: group 1: trisomy 8 as the sole cytogenetic anomaly ( n  = 20); group 2: trisomy 8 in addition to favourable chromosome aberrations (t(8;21)(q22;q22), t(15;17)(q22;q21), inv(16)(p13q22)) ( n  = 10); and group 3: trisomy 8 accompanied by other anomalies, in most cases of complex type ( n  = 21). Complete remission (CR) rates were 70%, 90% and 67% for groups 1, 2 and 3, respectively. Event-free survival (EFS) at 3 years differed significantly between patients with trisomy 8 only (37.5%), patients with trisomy 8 in combination with favourable aberrations (55.0%) and patients with trisomy 8 and other accompanying anomalies, mostly complex chromosome aberrations (9.0%) (group 1 v group 2: P  = 0.12; group 1 v group 3: P  = 0.005; group 2 v group 3: P  = 0.05). In this study patients with +8 as the sole cytogenetic anomaly had an intermediate prognosis, patients with +8 in addition to favourable chromosome aberrations maintained a good clinical outcome, and patients with +8 in combination with other abnormalities showed the worst prognosis.     

Prognostic significance of the Medical Research Council cytogenetic classification compared with the European LeukaemiaNet risk classification system in acute myeloid leukaemia

Fibrosis has been reported in some patients with immune thrombocytopenia (ITP) treated with thrombopoietin receptor agonists (TPO‐RA). However, fibrosis has also been reported in patients with various stages of ITP, who were TPO‐RA treatment‐naïve. In our study, we looked for fibrosis in bone marrow trephine biopsies taken at initial diagnosis from 32 adult patients with ITP. Ten of the 32 evaluated samples (31·25%) showed increased reticulin (Grade 1–2 on Bauermeister scale and Grade 0–1 on the European Consensus scale), which showed a positive correlation with ethnicity (0·3%) but did not correlate with disease severity, any clinical features or co‐morbidities.     

Long-term outcome of intensive chemotherapy for adults with de novo acute myeloid leukaemia (AML): the nationwide AML-92 study by the Finnish Leukaemia Group

OBJECTIVE: To investigate the long-term outcome of idarubicin- and cytarabine-based intensive chemotherapy in adult acute myeloid leukaemia (AML). PATIENTS AND METHODS: A total of 327 consecutive patients with de novo AML (promyelocytic leukaemia excluded) aged 16-65 yr were recruited into the study between September 1992 and December 2001. The latest follow-up data were collected in October 2006. After remission achievement with the first (conventional cytarabine) or second (high-dose cytarabine) chemotherapy cycle, three intensive consolidation courses each containing high- or intermediate-dose cytarabine were given. RESULTS: A total of 268 patients (82%) achieved complete remission (CR). CR rate was 82% and 84% for patients <60 and > or =60 yr of age, respectively. CR rates in patients with favourable (93%) and intermediate/normal karyotypes (87%) were significantly (P < 0.01) higher than CR rate in patients with adverse karyotype (61%). Median relapse-free survival (RFS) for the patients not transplanted in the first CR (n = 195) was 1.7 yr (95% CI: 0.81-2.60). At 4 yr, a plateau of 70% in RFS was reached for patients with favourable karyotypes. The 5-yr survival was 71%, 47% and 37% for the non-transplanted patients (n = 202) with favourable, intermediate/normal and intermediate/abnormal karyotypes, respectively, while only 8% of the patients having adverse karyotype were alive at 5 yr (P < 0.01). Of the patients with favourable, intermediate/normal or intermediate/abnormal karyotypes, respectively, 58%, 41% and 31% were expected to be alive at 10 yr. CONCLUSIONS: Idarubicin- and cytarabine-based intensive chemotherapy regimen is very effective in de novo AML for adult patients up to 65 yr of age. New treatment strategies are needed, however, to improve the outcome of the patients with intermediate and adverse karyotypes.     

Reappraisal of the clinical significance of CD7 expression in association with cytogenetics in de novo acute myeloid leukaemia

Debate exists over whether CD7 expression indicates an unfavourable prognosis in de novo acute myeloid leukaemia (AML). Meanwhile, the type of cytogenetics is a strong prognostic factor in AML. We analysed 256 de novo adult AML cases and found that the proportion of CD7+ cases increased stepwise from the cases with favourable cytogenetics to the cases with intermediate and unfavourable cytogenetics (3 out of 69 cases, 51 out of 140 cases and 25 out of 47 cases respectively, P < 0.0001). CD7-positivity adversely affected the survival only in the cases with unfavourable cytogenetics (P < 0.03). We recommend that CD7 expression in AML be interpreted in association with the cytogenetics.     

Cytogenetic findings in adult de novo acute myeloid leukaemia. A population-based study of 303/337 patients

Summary. During a 10-year period (1992–2001) in the region of Southern Denmark, 337 patients aged 15 years or older (range 16–93 years, median 67 years) were diagnosed with acute myeloid leukaemia (AML). Cytogenetic analysis was carried out in 90%, of whom 53% had clonal chromosome aberrations. Some 24% and 31% had only numerical or structural abnormalities respectively. The remaining patients showed both types of abnormalities. Ploidy levels in decreasing order were: pseudodiploidy, 41%; hyperdiploidy, 32%; and hypodiploidy, 27%. Pseudodiploidy characterizes type M3 (70%) and hypodiploidy M6 (56%). Recurrent cytogenetic abnormalities – t(8;21), t(15;17) and inv(16) – were found in 3·3%, 3·3% and 2·0% of all patients respectively. Prognostically intermediate and adverse aberrations were found in 39% and 44%, respectively, of those with an abnormal karyotype. Rare recurrent aberrations were found in two patients in this material. A previously described non-recurrent abnormality was found to be recurrent in one patient [der(20)t(11;20)(q13.2;p13)]. New, previously undescribed abnormalities were found in 41 patients. Statistically significant correlations were found between t(15;17) and young age ( P  < 0·001), inv(16) and young age ( P  < 0·006), −17 and M6 ( P  = 0·007), and M6 and complex karyotype with five or more unrelated aberrations ( P  = 0·004). We conclude that this truely population-based cytogenetic study of adult AML showed distributions of chromosome abnormalities that differ from those described so far.     

Prognostic significance of risk group stratification in elderly patients with acute myeloid leukaemia

Prognostic factors were studied in a series of 211 acute myeloid leukaemia (AML) patients over 60 years of age, treated at a single centre. The patients were allocated into three risk groups based on cytogenetics, occurrence of antecedent haematological disorder and leucocyte count. Only 3% had low-risk features, 39% had intermediate- and 58% had adverse-risk features. Complete remission (CR) was achieved in 43% of all patients. In multivariate analyses, the number of cycles needed to achieve CR and the risk group were significantly associated with the duration of CR. Median survival time for the entire cohort of patients was only 107 d. Advanced age, low induction treatment intensity, treatment during earlier years and adverse-risk group were associated with shorter overall survival times. Risk group classification may help selection of elderly patients with a good chance of benefiting from intensive treatment to actually receive such treatment, while sparing others with a low probability of survival benefit from toxic treatment. Low intensity induction treatment reduces the chance of obtaining complete remission, produces inferior survival times and should consequently be avoided when the aim is to obtain complete remission. In elderly AML patients, introducing age and re-evaluation of intermediate and good prognosis patients regarding response to induction treatment may improve the risk group classification.     

Cytogenetic abnormalities in childhood acute myeloid leukaemia: a Nordic series comprising all children enrolled in the NOPHO-93-AML trial between 1993 and 2001

Between 1993 and 2001, 318 children were diagnosed with acute myeloid leukaemia (AML) in the Nordic countries. The patient group comprised 237 children < 15 years of age with de novo AML, 42 children < 15 years with Down syndrome (DS) and de novo AML, 18 adolescents 15-18 years of age with de novo AML, and 21 children < 15 years with treatment-related AML (t-AML). The first group was all-inclusive, yielding an annual childhood de novo AML incidence of 0.7/100 000. Cytogenetic analyses were successful in 288 cases (91%), and clonal chromosomal abnormalities were detected in 211 (73%). The distribution of ploidy levels were pseudodiploidy (55%), hyperdiploidy (34%) and hypodiploidy (11%). The most common aberrations (> 2%) were + 8 (23%) (as a sole change in 6.2%), 11q23-translocations, including cryptic MLL rearrangements (22%) [t(9;11)(p21-22;q23) in 11%], t(8;21)(q22;q22) (9.0%), inv(16)(p13q22) (6.2%), -7/7q- (5.2%), and t(15;17)(q22;q12) (3.8%). Except for +8, these abnormalities were rare in group 2; only one DS patient had a t(8;21) and none had 11q23-translocations, t(15;17) or inv(16). In the t-AML group, three cases displayed 11q23-rearrangements, all t(9;11); and there were no t(8;21), t(15;17) or inv(16). Overall, the observed frequencies of t(8;21) and t(15;17) were lower, and frequencies of trisomy 8 and 11q23-translocations higher, than in previous studies. Furthermore, seven abnormalities that were previously reported as only single AML cases were also seen, meaning that der(4)t(4;11)(q26-27;q23), der(6)t(1;6)(q24-25;q27), der(7)t(7;11)(p22;q13), inv(8)(p23q11-12), t(11;17)(p15;q21), der(16)t(10;16)(q22;p13) and der(22)t(1;22)(q21;q13) are now classified as recurrent abnormalities in AML. In addition, 37 novel aberrations were observed, 11 of which were sole anomalies.     

Various distinctive cytogenetic abnormalities in patients with acute myeloid leukaemia aged 60 years and older express adverse prognostic value: results from a prospective clinical trial

Diagnostic cytogenetic abnormalities are considered important prognostic factors in patients with acute myeloid leukaemia (AML). However, the prognostic assessments have mainly been derived from patients with AML aged <60 years. Two recent studies of AML patients of 60 years and older proposed prognostic classifications with distinct discrepancies. To further study the prognostic value of cytogenetic abnormalities in this patient population, we have evaluated cytogenetic abnormalities in a series of 293 untreated patients with AML aged 60 years and older, included in a randomised phase 3 trial, also in relation to patient characteristics and clinical outcome. The most frequently observed cytogenetic abnormality was trisomy 8 (+8), in 31 (11%) patients. Abnormalities, such as -5, 5q-, abn(17p) and abn(17q), were almost exclusively present in complex karyotypes. A relatively favourable outcome was only observed in five patients with core-binding factor abnormalities t(8;21) and inv(16)/del(16)/t(16;16). However, most of the other evaluated cytogenetic abnormalities, such as 5q-, -7, +8, abn(17p), abn(17q), and complex aberrations expressed a more adverse prognosis when compared with patients with AML aged 60 years and older with a normal karyotype. Large studies to confirm the prognosis of individual cytogenetic aberrations are warranted.     

Unsuccessful diagnostic cytogenetic analysis is a poor prognostic feature in acute myeloid leukaemia

Chromosome banding analysis is the gold standard method for the identification of recurrent cytogenetic abnormalities in acute myeloid leukaemia (AML). It allows stratification of AML patients into subgroups with distinct responses to therapy and survival. Unfortunately, a variety of issues hamper cytogenetic evaluation in c. 10% of cases [unsuccessful cytogenetics (UC)] and the outcome of these patients is poorly understood. To better define the significance of UC in patients with AML, we compared the baseline characteristics and the prognostic impact of 94 (6%) patients, whose standard metaphase analysis yielded unacceptable results, to the remaining 1403 AML patients with successful cytogenetic analysis treated on successive Southwestern Oncology Group protocols. The incidence of UC increased with age, with peak incidence in patients older than 60 years. These patients had a lower response rate to induction chemotherapy (complete remission rate of 43%) and dismal 5‐year survival rates (16%), which was especially poor in patients older than 60 years (<5%). The complete remission and survival rates were similar to those seen in patients with unfavourable karyotype. The early death rate was not increased. These results suggest that UC increases with age and predict for poor outcomes, similar to the outcomes of patients with unfavourable karyotype.     

Clinical significance of serum thymidine kinase in adult T-cell leukaemia and acute myeloid leukaemia

To clarify the clinical and biological significance of serum thymidine kinase (TK) in adult T-cell leukaemia (ATL) associated with human lymphotropic virus type-I (HTLV-I) and in acute myeloid leukaemia (AML), TK was measured in 52 patients with ATL (acute ATL, 35 patients; lymphoma ATL, two patients; chronic ATL, 12 patients; smouldering ATL, three patients), and in 27 patients with AML (one FAB MO, one Ml, 10 M2, seven M3, five M4, one M5, one M6, one MU). In ATL patients, statistical analysis disclosed a close correlation between TK level and the leucocyte count (P<0–01), and absolute number of abnormal lymphocytes (P<0–01). However, no correlation was observed between serum lactic dehydrogenase (LDH) level and these items. Concerning the therapeutic response, a statistical difference was present in TK between complete remission and no response (P<005), but not in LDH. We also investigated a significant inverse correlation between TK level as well as LDH level and the length of survival after the initial diagnosis (P<001). In AML patients a close correlation of TK level with the count of leucocytes (P<001), percentage of blasts in the blood (P<005), therapeutic response (P<0–01) and the length of survival after the initial diagnosis (P< 005) was present.     

Spontaneous remission in acute myeloid leukaemia

A summary of the literature of adult patients with acute myeloid leukaemia (AML) who have undergone spontaneous remission (SR) is presented together with a report of a patient whose SR was accompanied by cytogenetic remission. There are less than 20 reports of SR since the 1980s. SR is by no means synonymous with cure, since the average duration of the remission is only 7·1±9·2 months. Neither infections nor transfusions are absolute requirements of SR.     

Clinical significance of residual disease during treatment in childhood acute myeloid leukaemia

In children with acute myeloid leukaemia (AML), morphological and karyotypic studies cannot precisely assess response to treatment, and less than one-third of patients have genetic markers for molecular studies of residual disease. We determined the usefulness of a four-colour flow cytometric strategy developed in our laboratory to study residual disease. We first compared the immunophenotypes of AML cells obtained from 54 children at diagnosis with those of cells from 59 normal or regenerating bone marrow samples. Forty-six of the 54 AML cases (85.2%) had immunophenotypes that allowed detection of 0.1-0.01% residual leukaemic cells. Of 230 bone marrow samples obtained from those 46 patients during and off treatment, 61 (26.5%) had >/= 0.1% AML cells by flow cytometry. We found that core binding factor-associated AML had a significantly better early treatment response. Mean (+/- standard error) 2-year survival estimate was 33.1 +/- 19.1% for patients with >/= 0.1% AML cells by flow cytometry after induction therapy, but 72.1 +/- 11.5% for those with < 0.1% AML cells (P = 0.022); overt recurrence of AML within the subsequent 6 months was significantly more likely in the former group. The assay described here holds promise for guiding the choice of post-remission treatment options in children with AML.     

The clinical spectrum of adult acute myeloid leukaemia associated with core binding factor translocations

To better understand the spectrum of adult acute myeloid leukaemia (AML) associated with core binding factor (CBF) translocations, 370 patients with newly diagnosed CBF-associated AML were analysed. Patients' age ranged from 16-83 years (median 39 years) with a slight male predominance (55%); 53% had inv(16); 47% had t(8;21). Patients with t(8;21) tended to be younger (P = 0.056), have lower peripheral blood white cell counts (P < 0.0001) and were more likely to have additional cytogenetic abnormalities (P < 0.0001). Loss of sex chromosome, del(9q) and complex abnormalities were more common among patients with t(8;21), while +22 and +21 were more common with inv(16). Overall, 87% [95% confidence interval (CI) 83-90%] of patients achieved complete response (CR) with no difference between t(8;21) and inv(16); however, the CR rate was lower in older patients due to increased resistant disease and early deaths. Ten-year overall survival (OS) was 44% (95% CI 39-50%) and, in multivariate analysis, was shorter with increasing age (P < 0.0001), increased peripheral blast percentage (P = 0.0006), in patients with complex cytogenetic abnormalities in addition to the CBF translocation (P = 0.021), and in patients with t(8;21) (P = 0.025). OS was superior in patients who received regimens with high-dose cytarabine, a combination of fludarabine and intermediate-dose cytarabine, or haematopoietic cell transplantation.     

Single agent thalidomide in patients with relapsed or refractory acute myeloid leukaemia

Thalidomide is a putative anti-angiogenesis agent that has significant anti-tumour activity in haematological malignancies with increased bone marrow angiogenesis, including multiple myeloma (MM) and myelodysplastic syndromes (MDS). Increased levels of the mitogen for angiogenesis, vascular endothelial growth factor (VEGF), correlate with worse survival in acute myeloid leukaemia (AML). A phase II trial of thalidomide was conducted in patients with relapsed- or refractory-AML previously treated with cytarabine-containing regimens. A total of 16 patients with refractory- or relapsed-AML were treated with thalidomide 200-800 mg orally daily (median dose 400 mg daily) for a median of 27 d (range, 3-94 d). Overall, one patient (6%) achieved complete remission (CR) lasting for 36 months, and two patients had a transient reduction in marrow blasts from 8% and 7% to less than 5% in both cases. There was no correlation between reduction in levels of angiogenesis markers and response. Toxicities related to thalidomide were significant, and precluded dose escalation beyond 400 mg orally daily in most patients. Although there appears to be some evidence of biological activity, single agent thalidomide is not an optimal choice of therapy for salvaging patients with relapsed- or refractory-AML. Thalidomide analogues with more potent immunomodulatory activities and more favourable toxicity profiles may offer more promise as anti-AML therapy.     

Patients with de novo acute myeloid leukaemia and complex karyotype aberrations show a poor prognosis despite intensive treatment: a study of 90 patients

The clinical significance of complex chromosome aberrations for adults with acute myeloid leukaemia (AML) was assessed in 920 patients with de novo AML who were karyotyped and treated within the German AML Cooperative Group (AMLCG) trials. Complex chromosome aberrations were defined as three or more numerical and/or structural chromosome aberrations excluding translocations t(8;21)(q22;q22), t(15;17)(q22;q11-q12) and inv(16)(p13q22). Complex chromosome anomalies were detected in 10% of all cases with a significantly higher incidence in patients > or = 60 years of age (17.8% vs. 7.8%, P < 0.0001). Clinical follow-up data were available for 90 patients. Forty-five patients were < 60 years of age and were randomly assigned to double induction therapy with either TAD-TAD [thioguanine, daunorubicin, cytosine arabinoside (AraC)] or TAD-HAM (high-dose AraC, mitoxantrone). Twenty-one patients achieved complete remission (CR) (47%), 20 patients (44%) were non-responders and 9% of patients died during aplasia (early death). The median overall survival (OS) was 7 months and the OS rate at 3 years was 12%. Patients receiving TAD-HAM showed a significantly higher CR rate than patients receiving TAD-TAD (56% vs. 23%, P = 0.04). Median event-free survival was less than 1 month in the TAD-TAD group and 2 months in the TAD-HAM group, respectively (P = 0.04), with a median OS of 4.5 months vs. 7.6 months (P = 0.13) and an OS after 3 years of 7.6% vs. 19.6%. Forty-five patients were > or = 60 years of age: 28 of these patient were treated for induction using one or two TAD courses and 17 cases received TAD-HAM with an age-adjusted reduction of the AraC dose. The CR rate was 44%, 38% were non-responders and 18% experienced early death. The median OS was 8 months and the OS rate at 3 years was 6%. In conclusion, complex chromosome aberrations in de novo AML predicted a dismal outcome, even when patients were treated with intensive chemotherapy. Patients under the age of 60 years with complex aberrant karyotypes may benefit from HAM treatment during induction. However, long-term survival rates are low and alternative treatment strategies for remission induction and consolidation are urgently needed.     

The prognostic significance of morphological features in childhood acute lymphoblastic leukaemia

A consecutive series of 209 children with acute lymphoblastic leukaemia (ALL) presenting to a regional referral unit between 1970 and 1977 was studied. The following morphological features in the initial bone marrow were recorded: blast size, percentage periodic acid-Schiff (PAS) and oil-red-O (ORO) positivity, percentage of blasts with vacuoles, and acid phosphatase positivity. The blasts were also coded according to the FAB (LI-3) classification. When analysed separately, increasing blast size was significantly related to the length of first remission (P= 0.01). However, this was almost entirely due to its association with the FAB L2 type of disease which also had a highly significant influence on length of first remission (P> 0.0001) independent of all other factors. Patients with L3 disease had blasts with heavy vacuolation, ORO positivity and displayed monoclonal surface immunoglobulin and their prognosis was very poor. The percentage of vacuolated blasts and ORO positivity otherwise showed no influence on prognosis. Fine granularity of PAS staining in lymphoblasts showed no prognostic value but the trend of longer remission duration with increase in percentage of PAS coarse granularity and blocks, was statistically significant (P= 0.006). This relationship was partly due to a correlation with the presence of mediastinal mass and L2 disease, but was still independent of all other prognostic factors. In a smaller number (39) of the series of patients on whom cell surface markers were available, we were unable to demonstrate a correlation between T-derived blasts and the L1 and L2 classification; but there was a strong correlation with polar acid phosphatase positivity in T-derived blasts.