Impact of chromosomal translocations on prognosis in childhood acute lymphoblastic leukemia

Multidisciplinary care in pediatric oncology

This paper describes the significant advances in the treatment of childhood cancer and supportive care that have occurred over the last several decades and details how these advances have led to improved survival and quality of life (QOL) for children with cancer through a multidisciplinary approach to care. Advances in the basic sciences, general medicine, cooperative research protocols, and policy guidelines have influenced and guided the multidisciplinary approach in pediatric oncology care across the spectrum from diagnosis through long-term survival. Two case studies are provided to highlight the nature and scope of multidisciplinary care in pediatric oncology care.

High hyperdiploid childhood acute lymphoblastic leukemia

High hyperdiploidy (51-67 chromosomes) is the most common cytogenetic abnormality pattern in childhood B-cell precursor acute lymphoblastic leukemia (ALL), occurring in 25-30% of such cases. High hyperdiploid ALL is characterized cytogenetically by a nonrandom gain of chromosomes X, 4, 6, 10, 14, 17, 18, and 21 and clinically by a favorable prognosis. Despite the high frequency of this karyotypic subgroup, many questions remain regarding the epidemiology, etiology, presence of other genetic changes, the time and cell of origin, and the formation and pathogenetic consequences of high hyperdiploidy. However, during the last few years, several studies have addressed some of these important issues, and these, as well as previous reports on high hyperdiploid childhood ALL, are reviewed herein.

Allogeneic hematopoietic cell transplantation for patients with high-risk acute lymphoblastic leukemia in first or second complete remission using fractionated total-body irradiation and high-dose etoposide: a 15-year experience

OBJECTIVE

The rationale for this retrospective study was to identify the long-term overall and event-free survival, relapse, and treatment-related mortality rates of high-risk pediatric and adult first (CR1) and second remission (CR2) patients with acute lymphoblastic leukemia (ALL) who were treated with a single preparatory regimen consisting of fractionated total-body irradiation (FTBI) and high-dose etoposide (VP-16) prior to allogeneic hematopoietic cell transplantation.

PATIENTS AND METHODS

Over a 15-year period at Stanford University Medical Center, 85 consecutive high-risk pediatric (up to age 17 years; n=41) and adult (age 18-55 years; n=44); patients with leukemia (ALL) in CR1 (n=55) and CR2 (n=30) received HLA-matched sibling allogeneic bone marrow or peripheral blood progenitor grafts after being treated with FTBI (1320 cGy) and high-dose VP-16 (60 mg/kg) as their preparatory regimen. The majority of patients transplanted in CR1 (n=45) had high-risk features, including age above 30 years, white blood cell count at presentation exceeding 25000/microL, extramedullary disease, need for more than 4 weeks of induction chemotherapy to achieve CR, or high-risk chromosomal translocations. Most patients transplanted in CR1 were adults (n=39), whereas patients in CR2 were primarily children or adolescents (n=25).

RESULTS

The 10-year Kaplan-Meier estimates of relapse were significantly (p=0.05) lower in CR1 patients (15%+/-10%) than in CR2 patients (33%+/-20%). Relapse was the most common cause of treatment failure in patients transplanted in CR2. There was a significantly (p=0.05) higher rate of chronic graft-vs-host disease in CR1 (32%+/-14%) compared with CR2 (9%+/-11%) patients; however, overall survival for patients transplanted in CR1 (66%+/-14%) was comparable (p=0.67) to that of patients transplanted in CR2 (62%+/-19%). Event-free survival rates also were similar (p=0.53) between CR1 (64%+/-14%) and CR2 (61%+/-18%) patients. Treatment-related mortality rates were equivalent (p=0.51) between CR1 and CR2, as well as between Philadelphia chromosome (Ph) positive (Ph(+))and Ph(-) (p=0.23) ALL patients.

CONCLUSION

Overall, FTBI/VP-16 is a highly effective preparatory regimen that provides durable remissions for patients receiving allogeneic hematopoietic cell transplantation for high-risk ALL in CR1 or CR2.

Multiplex RT-PCR assay for the detection of major fusion transcripts in Taiwanese children with B-lineage acute lymphoblastic leukemia

BACKGROUND

The classification of B-lineage acute lymphoblastic leukemia (ALL) by specific chromosomal translocations may have prognostic implications. Reverse transcriptase-polymerase chain reaction (RT-PCR) assay is a useful tool for the detection of fusion transcript resulting from specific chromosomal translocation of the leukemic cells. In general, fusion transcripts are determined individually, a process which is labor intensive in order to detect all major fusion transcripts.

PROCEDURE

We use a multiplex RT-PCR assay to detect both the CML- and ALL-type BCR-ABL transcripts of the t(9;22), all described variants of the E2A-PBX1 transcripts of t(1;19), the MLL-AF4 transcripts of t(4;11), and all described variants of TEL-AML1 (also termed ETV6-CBFA2) of the cryptic t(12;21) in 165 leukemic samples at diagnosis.

RESULTS

The study yielded a completely concordant result with those obtained by the individual RT-PCR assay. In this cohort of Taiwan children, the relative frequencies of the four translocations of B-lineage ALL were as following: 6% with ALL-type t(9;22)/BCR-ABL, 7% t(1;19)/E2A-PBX1, 3% t(4;11)/MLL-AF4, and 18% t(12;21)/TEL-AML1, comparable to those in the Western countries.

CONCLUSION

Multiplex RT-PCR assay is an efficient, sensitive, accurate, and cost-effective diagnostic tool, which will likely improve our ability in accurately and rapidly risk-stratifying children with ALL.

The detection and significance of chromosomal abnormalities in childhood acute lymphoblastic leukaemia

In childhood acute lymphoblastic leukaemia (ALL), cytogenetics plays an essential role in diagnosis and prediction of outcome. Conventional cytogenetic analysis, complemented by fluorescence in situ hybridization (FISH), is highly effective in the accurate detection of chromosomal abnormalities. For the precise identification of specific genetic changes, molecular techniques may be applied. Chromosomal changes in ALL may be of structural or numerical type. A large number of established structural chromosomal rearrangements have now been described for which the genetic alterations and effect on prognosis are well known. These include t(9;22)(q34;q11) and BCR/ABL, rearrangements of 11q23 involving MLL, t(12;21)(p13;q22) with the ETV6/AML1 fusion, t(1;19)(q23;p13) with E2A/PBX1, t(8;14)(q24;q32) and the immunoglobulin genes. Genetic changes associated with T ALL are also known, although their effect on outcome is less pronounced. Rare chromosomal abnormalities are continually being discovered in small patient subgroups leading to the identification of new ALL associated genetic changes. Alterations in chromosome number have a strong impact on outcome in childhood ALL. The association of a high hyperdiploid karyotype (51-65 chromosomes) with a good prognosis has been known for more than 20 years. Conversely, the loss of chromosomes in the near-haploid group (23-28 chromosomes) indicates a poor outcome. New methods of cancer classification involving gene expression profiling may eventually supercede cytogenetic analysis in the diagnosis and prediction of outcome in leukaemia. It is more likely that they will be used in a complementary approach alongside cytogenetic, FISH and molecular analysis to guide patient management in childhood ALL.

Prognostic value of tumoral ploidy in a series of spanish patients with acute lymphoblastic leukemia

The prognostic value of tumoral ploidy and its relation with nonrandom chromosome alterations were analyzed in 89 cases of acute lymphoblastic leukemia. Ploidy is associated with the number of nonrandom chromosome alterations and survival. The pseudodiploid and hypodiploid groups had a high incidence of nonrandom alterations and poor survival while the diploid and high hyperdiploid groups had a lower incidence of nonrandom alterations and longer survivals. The patients in the low hyperdiploid group with random alterations received the same treatment as the diploid and high hyperdiploid groups but had poor survivals. Our analysis confirms that ploidy is a very important prognostic factor and suggests that patients with low hyperdiploidy should receive intensive therapies similar to those of patients in the groups with a high number of nonrandom alterations.

TEL-AML1 Fusion Transcript in Relapsed Childhood Acute Lymphoblastic Leukemia

The cryptic translocation t(12;21)(p13;q22) has been recently recognized as the most common genetic rearrangement in B-lineage childhood acute lymphoblastic leukemia (ALL). The resulting fusion transcript, termed TEL-AML1, has been associated with an excellent prognosis at initial ALL diagnosis. Hence, we postulated that the incidence of TEL-AML1 fusion should be lower in patients with ALL relapse. To address this assumption and to investigate the prognostic significance of TEL-AML1 expression in relapsed childhood ALL, bone marrow samples of 146 children were analyzed by reverse-transcriptase (RT)-polymerase chain reaction (PCR). All children were treated according to Berlin-Frankfurt-Münster (BFM) ALL relapse trial protocols (ALL-REZ BFM 90-96). Their clinical features and outcome were compared with those of 262 patients who could not be tested due to lack of bone marrow samples. Thirty-two of 146 children with relapsed ALL were TEL-AML1–positive. Four of the negative patients had T-lineage and nine Philadelphia chromosome (Ph1)-positive leukemia. Thus, the incidence ofTEL-AML1 in relapsed Ph1-negative, B-cell precursor ALL is 32 of 133 (24%). The 32 TEL-AML1–positive and 101 negative patients differed significantly with respect to duration of last remission (42.5 v 27 months; P = .0001) and age at initial diagnosis (53.5 v 74 months;P = .0269). At a median follow-up time of 21.5 months, children positive for TEL-AML1 had a significantly (P = .0011) higher probability of event-free survival (EFS; 0.79 v 0.33). The predominant majority of patients had been treated for initial ALL according to German multicenter BFM (108 of 133) or Cooperative ALL study group (CoALL) (19 of 133) frontline protocols. The comparison of tested and not-tested (N = 262) patients showed no significant difference.TEL-AML1 positivity predicted a favorable short-term outcome; long-term results are unknown. Screening for TEL-AML1 should become routine at relapse diagnosis and might be used for therapy stratification in future trials.

TEL-AML1 Fusion Transcript in Relapsed Childhood Acute Lymphoblastic Leukemia

The cryptic translocation t(12;21)(p13;q22) has been recently recognized as the most common genetic rearrangement in B-lineage childhood acute lymphoblastic leukemia (ALL). The resulting fusion transcript, termed TEL-AML1, has been associated with an excellent prognosis at initial ALL diagnosis. Hence, we postulated that the incidence of TEL-AML1 fusion should be lower in patients with ALL relapse. To address this assumption and to investigate the prognostic significance of TEL-AML1 expression in relapsed childhood ALL, bone marrow samples of 146 children were analyzed by reverse-transcriptase (RT)-polymerase chain reaction (PCR). All children were treated according to Berlin-Frankfurt-Münster (BFM) ALL relapse trial protocols (ALL-REZ BFM 90-96). Their clinical features and outcome were compared with those of 262 patients who could not be tested due to lack of bone marrow samples. Thirty-two of 146 children with relapsed ALL were TEL-AML1–positive. Four of the negative patients had T-lineage and nine Philadelphia chromosome (Ph1)-positive leukemia. Thus, the incidence ofTEL-AML1 in relapsed Ph1-negative, B-cell precursor ALL is 32 of 133 (24%). The 32 TEL-AML1–positive and 101 negative patients differed significantly with respect to duration of last remission (42.5 v 27 months; P = .0001) and age at initial diagnosis (53.5 v 74 months;P = .0269). At a median follow-up time of 21.5 months, children positive for TEL-AML1 had a significantly (P = .0011) higher probability of event-free survival (EFS; 0.79 v 0.33). The predominant majority of patients had been treated for initial ALL according to German multicenter BFM (108 of 133) or Cooperative ALL study group (CoALL) (19 of 133) frontline protocols. The comparison of tested and not-tested (N = 262) patients showed no significant difference.TEL-AML1 positivity predicted a favorable short-term outcome; long-term results are unknown. Screening for TEL-AML1 should become routine at relapse diagnosis and might be used for therapy stratification in future trials.

Prognostic impact of bone marrow karyotype in childhood acute lymphoblastic leukaemia: Swedish experiences 1986-91

The prognostic value of cytogenetic classification in acute lymphoblastic leukaemia (ALL) was evaluated in Swedish children below 16 years of age (n = 372) diagnosed between 1986 and 1991. A bone marrow karyotype was obtained in 281 cases, of which 149 (53%) showed clonal abnormalities. Event-free survival (p-EFS) was 0.64-0.69 in patients with diploid and pseudodiploid karyotype. Patients with massive hyperdiploidy (> 50 chromosomes) had the best outcome (p-EFS = 0.76) and those with hypodiploidy (< 46 chromosomes) had the worst (p-EFS = 0.33). White blood cell count and age were the strongest predictors of outcome. The karyotype reached borderline significance. The diagnostic karyotype was also a predictor of outcome after relapse, with hyperdiploid patients doing better than the others. The presence of a structural chromosomal abnormality did not constitute a negative prognostic factor when intensive chemotherapy was given.

Regional cancer cytogenetics: a report on 1,143 diagnostic cases

The results of studies from a regional cancer cytogenetics diagnostic service are reported. In a 10-year period, 1,143 marrow samples from patients with newly diagnosed leukemia and myelodysplastic syndrome were referred. Successful studies were completed on 992 cases (87%). Among all referred cases, the rates of detection of cytogenetically abnormal clones were 95% for chronic myelogenous leukemia (CML), 54% for acute lymphoblastic leukemia (ALL), 51% for acute myeloid leukemia (ANLL), and 43% for myelodysplastic syndrome (MDS). Of 169 cases of CML studied, 90.5% bore the standard Philadelphia chromosome (Ph), 3.55% had an unusual Ph, and 5.33% were Ph-negative. Among the 59 cases of cytogenetically abnormal MDS, common abnormalities observed were trisomy 8 and changes resulting in loss of material from the long arm of chromosomes 5 and 7, and 20q-. Of the 168 abnormal ANLL, there was a strikingly non-random pattern of aneuploidy, with monosomy 7 and trisomy 8 predominating. Common structural changes observed were changes resulting in loss of material from the long arm of chromosomes 5 and 7, trisomy 8, rearrangements of 11q23, t(15;17), t(8;21), rearrangements of 12q13 and 3q, inversion 16, trisomy 11, Ph, trisomy 21, t(6;9) and t(1;22). The differences between adult and pediatric findings were minor, with the exception of chromosome 5 abnormalities, which were common among adults with ANLL but rare in the pediatric cases. There were 273 ALLs with abnormal cytogenetic findings. There was preferential gain of chromosomes 21, X, 14, 6, 4, 18, 17, and 10 (in decreasing order of frequency) in leukemic clones. Of the 193 ALLs with structural changes, many fell into-well-defined categories with established correlations to FAB subtypes. Common changes in ALL were rearrangements of 9p, 12p, 6q, TCR loci, 11q23, Ig loci, and 8q24, and duplication of 1q, Ph, i(17q), t(1;19), i(9q) and dic(9;12). The detailed documentation of the cytogenetic findings in this relatively large, single-institution study will likely facilitate the further characterization of rare, primary cytogenetic changes associated with leukemias and MDS. From a managed health care perspective, regional cancer cytogenetic services may be cost-effective alternatives to single-institution laboratories.

Allogeneic bone marrow transplant in pediatric patients with high-risk hematopoietic malignancies early in the course of their disease

PURPOSE

The purpose of this study was to investigate the role of bone marrow transplant (BMT) early in the course of disease for pediatric patients with high-risk leukemia using a preparatory regimen of fractionated total body irradiation (FTBI) and etoposide (VP-16).

PATIENTS AND METHODS

Those studied were 33 patients aged < or =18 years with either acute leukemia in first complete remission (CR) (n = 29) or chronic myelogenous leukemia (CML) in first chronic phase (n = 4) who received 1,320 cGy FTBI followed by high-dose VP-16 (60 mg/kg) as a preparatory regimen for BMT from matched sibling donors. Patients with acute leukemia included 18 with acute nonlymphocytic leukemia (ANLL), one with biphenotypic acute leukemia (BAL), and 10 with selected "high-risk" acute lymphocytic leukemia (ALL). Patients with ALL were selected for a high risk for recurrence: those who failed standard remission induction chemotherapy, had a t(9;22) or t(4;11) chromosomal translocation, or had certain clinical high-risk features.

RESULTS

At the time of analysis, 28 patients are alive, all of them in continued complete remission for 1.1-7.8 years (median, 5.3 years; mean, 4.9 years). The Kaplan-Meier projected event-free survival (EFS) is 84.5% at 7 years, and the actuarial recurrence hazard is 6.5%. All surviving patients have a performance status of >80%.

CONCLUSION

This result of early BMT in a two-institution study of pediatric patients with hematopoietic malignancies suggests that (a) matched sibling allogeneic BMT after conditioning with FTBI and high-dose VP-16 is an excellent treatment for pediatric patients with high-risk leukemia, and (b) children may have a better prognosis than adults treated with allogeneic BMT. Larger multiinstitutional cooperative trials for pediatric patients are needed to confirm this result.

Gender and treatment outcome in childhood lymphoblastic leukaemia: report from the MRC UKALL trials

We have examined the factors influencing prognosis in over 4000 children with acute lymphoblastic leukaemia (ALL) aged 1-14 who have been treated on consecutive MRC UKALL trials from 1972 to 1990. During this time the results of treatment have improved steadily but are consistently superior in girls when compared with boys; the 5-year event-free survival in girls improving from 51% to 71% and in boys from 31% to 57%. These results were independent of age and presenting leucocyte count. Boys not only had a testicular relapse rate of 10% but an excess of bone marrow relapse, particularly evident after 2 years from diagnosis. Other prognostic factors included organomegaly and the morphology of leukaemic blast cells; immunophenotype of the leukaemia, however, had no independent significance after allowance for age, sex and leucocyte count. The influence of sex on prognosis was reaffirmed when we examined various methods of identifying children at highest risk of treatment failure for whom alternative therapy such as bone marrow transplantation might be justified. In MRC UKALL X children had been deemed 'high risk' on the basis of leucocyte count alone, but with further follow-up it has become apparent that girls with an initial leucocyte count of > 100 x 10(9)/l have a similar prognosis to boys with a lower count. We therefore derived a risk score based on sex, age and count which has given better discrimination between standard risk (66% 5-year survival) and poor risk (39%) survival than other methods. This group of worse-risk children includes 16% of boys but only 3% of all girls. Gender remains an important prognostic factor in UKALL trials and there are very few girls who are at highest risk of treatment failure. The reasons for this remain unclear, but the pattern of relapses suggests that boys more often get inadequate systemic therapy. We postulate that the reasons for treatment failure may relate to sensitivity to continuing (maintenance) chemotherapy.

Intensification of treatment and survival in all children with lymphoblastic leukaemia: results of UK Medical Research Council trial UKALL X. Medical Research Council Working Party on Childhood Leukaemia

The UK Medical Research Council trial MRC UKALL X was designed to investigate the benefit of one or two courses of additional intensification therapy in children with acute lymphoblastic leukaemia receiving standard treatment. From 1985 to 1990 1612 children, comprising more than 90% of eligible cases in the UK, were treated with intensive induction therapy, central nervous system directed therapy with cranial irradiation and intrathecal methotrexate, and continuing treatment for 2 years. 1171 children were randomised to receive additional intensification therapy at 5 weeks, 20 weeks, both, or neither. At follow-up of at least 3 years disease-free survival for all children at 5 years was 62% (95% confidence interval [Cl] 60.0-64.4), a significant improvement over the 56% (53.0-59.6) found in the preceding MRC UKALL trial. The 5-year disease-free survival was 71% (65.5-76.1) for children randomised to two blocks of intensification therapy, this being significantly better than the 62% (56.6-68.0), 61% (55.7-67.1), and 57% (50.9-62.7) rates for the groups randomised to one intensification block at 5 weeks, one at 20 weeks, and no intensification, respectively. The benefits of intensification therapy were seen irrespective of clinical factors known to influence outcome such as age, sex, and initial leucocyte count. We conclude that the addition of two courses of intensification therapy has produced a 14% improvement in disease-free survival and an 11% improvement in overall survival for the randomised patients. This additional treatment is of benefit to all children with acute lymphoblastic leukaemia, even those traditionally deemed at lower risk of relapse.

Detection of chromosome 11q23 involving translocations by pulsed field gel electrophoresis

Translocations involving chromosome band 11q23 are associated with acute lymphocytic and myelomonocytic leukemias with poor clinical prognosis. Pulsed-field gel electrophoresis (PFGE) was used to characterize the breakpoint region that has been mapped within a 300-kb fragment between the genes CD3G and PBGD. Using CD3G as a marker on SfuI-restricted DNA separated by PFGE, we detected a rearrangement involving 11q23 in the cell line B1 with a t(4;11) and in the leukemic cells of two patients, one with a t(2;11) and one with a t(11;19). In comparison, lymphoblastoid cell lines established from normal peripheral blood lymphocytes of these two patients had a normal karyotype and showed germline configuration, thus excluding RFL polymorphisms. Digestion of DNA with BssHII or SalI showed heterogeneity of 11q23 involving breakpoints. A rearrangement in the t(4;11) containing lymphoma cell line Karpas422 was seen only with the chromosome 4 probe KIT on SalI-digested DNA. PFGE is a reliable method for the mapping and detection of complex breakpoint regions. The breakpoints on 11q23 involve different introns of the highly spliced HRX/ALL-1/MLL gene.

Extremely poor prognosis of pediatric acute lymphoblastic leukemia with translocation (9;22): updated experience

Approximately five percent of pediatric acute lymphoblastic leukemias (ALL) contain a translocation (9;22)(q34;q11) which results in rearrangement of the bcr and abl genes. At a median follow-up of 5 years, we assessed the prognostic implications of translocation (9;22) in 434 children receiving intensive treatment for ALL. Four-year event-free and overall survivals were only 0% and 20%, respectively, in 15 children with translocation (9;22), but were 81% and 89%, respectively, in 419 children lacking translocation (9;22) (P < 0.001). Based on these findings, we recommend very intensive treatment approaches for all children with translocation (9;22)-positive ALL.