Early response to induction therapy as a predictor of disease-free survival and late recurrence of childhood acute lymphoblastic leukemia: a report from the Childrens Cancer Study Group

Flow cytometric minimal residual disease measurement accounting for cytogenetics in children with non-high-risk acute lymphoblastic leukemia treated according to the ALL-MB 2008 protocol

BACKGROUND

Quantitative measurement of minimal residual disease (MRD) is the "gold standard" for estimating the response to therapy in childhood B-cell precursor acute lymphoblastic leukemia (BCP-ALL). Nevertheless, the speed of the MRD response differs for different cytogenetic subgroups. Here we present results of MRD measurement in children with BCP-ALL, in terms of genetic subgroups with relation to clinically defined risk groups.

METHODS

A total of 485 children with non-high-risk BCP-ALL with available cytogenetic data and MRD studied at the end-of-induction (EOI) by multicolor flow cytometry (MFC) were included. All patients were treated with standard-risk (SR) of intermediate-risk (ImR) regimens of "ALL-MB 2008" reduced-intensity protocol.

RESULTS AND DISCUSSION

Among all study group patients, 203 were found to have low-risk cytogenetics (ETV6::RUNX1 or high hyperdiploidy), while remaining 282 children were classified in intermediate cytogenetic risk group. For the patients with favorable and intermediate risk cytogenetics, the most significant thresholds for MFC-MRD values were different: 0.03% and 0.04% respectively. Nevertheless, the most meaningful thresholds were different for clinically defined SR and ImR groups. For the SR group, irrespective to presence/absence of favorable genetic lesions, MFC-MRD threshold of 0.1% was the most clinically valuable, although for ImR group the most informative thresholds were different in patients from low-(0.03%) and intermediate (0.01%) cytogenetic risk groups.

CONCLUSION

Our data show that combining clinical risk factors with MFC-MRD measurement is the most useful tool for risk group stratification of children with BCP-ALL in the reduced-intensity protocols. However, this algorithm can be supplemented with cytogenetic data for part of the ImR group.

Top Ten Contributions of Pediatric Hematology/Oncology to the Diagnosis and Treatment of Acute Lymphoblastic Leukemia

Monumental progress has occurred in the diagnosis and treatment of childhood acute lymphoblastic leukemia dating back to the classic paper of Farber and colleagues in 1948. This historical review from the perspective of an individual, familiar with many of the waystations on this superhighway, will offer an admittedly personal review of the top 10 major contributions to the field. Fortunately, there have been many more additional advances beyond these 10 as we have witnessed an impressive improvement in overall survival from a few months 75 years ago to a cure rate of 85% in the world's more advanced countries. Other workers in the field assuredly would create a different list and ranking of these advances but the takeaway summation of the make-up and order of these lists is that advances have yielded improved and prolonged responses, a rational understanding of factors, both clinical and biological, that predict response and prognosis, the application of those factors to tailor therapy's intensity and duration to those factors and to discover and design modalities and targets of therapy that target our much more complete understanding of this most common malignancy of infants and children. On a very personal note, I vividly recall an early, ill-advised decision to devote my academic career to hematology/oncology, with one glaring exception, acute lymphoblastic leukemia, and other malignancies. The stark realities of clinical practice and the harsh unmet needs and mostly unanswered challenges redirected my path that resulted in participation in many of these advances, making my own journey so gratifying and that of most of our patients so favorable.

Analysis of clinical profile and role of various prognostic factors in early bone marrow response in children with acute lymphoblastic leukemia treated by Modified Multicenter Protocol (MCP) 841 protocol: Experience from a tertiary care center in North India

BACKGROUND

It is important to study the clinical profile of pediatric patients with acute lymphoblastic leukemia (ALL) and assess various prognostic factors implicated in response to induction chemotherapy for optimal treatment outcomes in India. The present study was done to evaluate the clinical profile and to find the correlation of day 7 and day 28 marrow blast response with already established prognostic factors in children with ALL in the region of North India using MCP 841 protocol for all patients.

METHODS

A total of 60 children up to ages 14 years with ALL were given treatment in the form of induction remission (MCP-841 protocol) I1 cycle (induction 1) therapy for 29 days. Complete hemogram for blast cells and bone marrow examination (bone marrow aspiration and, if required, bone marrow biopsy) was done on days 7 and 28 (completion of I1 cycle) to see early bone marrow response. Early response to induction therapy was compared in patients with and without high-risk factors, and results were analyzed statistically.

RESULTS

Out of 60 enrolled children, 56 (93.4%) patients were in complete remission at the end of induction 1 cycle. Various risk factors were found to be of prognostic significance in first remission and early response to induction therapy were initial total leukocyte count (TLC) at presentation, immunophenotype of ALL; while other factors including age and sex was not found to be significant.

CONCLUSION

Prevalence and significance of various prognostic factors implicated in pediatric ALL tend to be different in various populations. A better understanding of such factors in these populations will help in the tailoring of risk-adapted treatment protocols to local needs.

Characterization of leukemias with ETV6-ABL1 fusion

To characterize the incidence, clinical features and genetics of ETV6-ABL1 leukemias, representing targetable kinase-activating lesions, we analyzed 44 new and published cases of ETV6-ABL1-positive hematologic malignancies [22 cases of acute lymphoblastic leukemia (13 children, 9 adults) and 22 myeloid malignancies (18 myeloproliferative neoplasms, 4 acute myeloid leukemias)]. The presence of the ETV6-ABL1 fusion was ascertained by cytogenetics, fluorescence in-situ hybridization, reverse transcriptase-polymerase chain reaction and RNA sequencing. Genomic and gene expression profiling was performed by single nucleotide polymorphism and expression arrays. Systematic screening of more than 4,500 cases revealed that in acute lymphoblastic leukemia ETV6-ABL1 is rare in childhood (0.17% cases) and slightly more common in adults (0.38%). There is no systematic screening of myeloproliferative neoplasms; however, the number of ETV6-ABL1-positive cases and the relative incidence of acute lymphoblastic leukemia and myeloproliferative neoplasms suggest that in adulthood ETV6-ABL1 is more common in BCR-ABL1-negative chronic myeloid leukemia-like myeloproliferations than in acute lymphoblastic leukemia. The genomic profile of ETV6-ABL1 acute lymphoblastic leukemia resembled that of BCR-ABL1 and BCR-ABL1-like cases with 80% of patients having concurrent CDKN2A/B and IKZF1 deletions. In the gene expression profiling all the ETV6-ABL1-positive samples clustered in close vicinity to BCR-ABL1 cases. All but one of the cases of ETV6-ABL1 acute lymphoblastic leukemia were classified as BCR-ABL1-like by a standardized assay. Over 60% of patients died, irrespectively of the disease or age subgroup examined. In conclusion, ETV6-ABL1 fusion occurs in both lymphoid and myeloid leukemias; the genomic profile and clinical behavior resemble BCR-ABL1-positive malignancies, including the unfavorable prognosis, particularly of acute leukemias. The poor outcome suggests that treatment with tyrosine kinase inhibitors should be considered for patients with this fusion.

Outcome of Children with Standard-Risk T-Lineage Acute Lymphoblastic Leukemia--Comparison among Different Treatment Strategies

BACKGROUND

Children with T-lineage acute lymphoblastic leukemia ALL (T-ALL) historically have had inferior outcomes compared with the children with precursor-B ALL (B-ALL). After 1995, the Children's Cancer Group (CCG) treated patients with B- and T-ALL according to the National Cancer Institute (NCI) risk criteria, basing risk stratification on age and white blood cell (WBC) count regardless of immunophenotype. The Pediatric Oncology Group (POG) treated all the patients with T-ALL on separate, generally more intensive protocols than those used to treat the patients with B-ALL.

PROCEDURE

We compared the outcomes of children with T-ALL and NCI standard-risk (SR) criteria treated on CCG and POG trials between 1996 and 2005. CCG SR-ALL 1952 and 1991 enrolled 80 and 86 patients with T-ALL, respectively, utilizing a reduced intensity Berlin-Frankfurt-Münster backbone. Treatment was intensified for slow early responders and only patients with overt central nervous system leukemia received cranial irradiation. Eighty-four patients with T-ALL and SR features were enrolled on POG 9404 comprising more intensive therapy with all patients receiving cranial irradiation.

RESULTS

The 7-year event-free survival (EFS) for patients with SR T-ALL on CCG 1952, CCG 1991, and POG 9404 were 74.1 ± 5.8%, 81.8 ± 5.3%, and 84.2 ± 4.3%, respectively (P = 0.18). Overall 7-year survivals were 86.1 ± 4.6%, 88.3 ± 4.4%, 89.1 ± 3.6%, respectively (P = 0.84).

CONCLUSIONS

Comparable high rates of EFS and long-term survival were achieved with all three regimens, with the CCG regimens utilizing a less intensive chemotherapy backbone without prophylactic cranial irradiation for patients with SR T-ALL.

Predicting relapse risk in childhood acute lymphoblastic leukaemia

Intensive multi-agent chemotherapy regimens and the introduction of risk-stratified therapy have substantially improved cure rates for children with acute lymphoblastic leukaemia (ALL). Current risk allocation schemas are imperfect, as some children are classified as lower-risk and treated with less intensive therapy relapse, while others deemed higher-risk are probably over-treated. Most cooperative groups previously used morphological clearance of blasts in blood and marrow during the initial phases of chemotherapy as a primary factor for risk group allocation; however, this has largely been replaced by the detection of minimal residual disease (MRD). Other than age and white blood cell count (WBC) at presentation, many clinical variables previously used for risk group allocation are no longer prognostic, as MRD and the presence of sentinel genetic lesions are more reliable at predicting outcome. Currently, a number of sentinel genetic lesions are used by most cooperative groups for risk stratification; however, in the near future patients will probably be risk-stratified using genomic signatures and clustering algorithms, rather than individual genetic alterations. This review will describe the clinical, biological, and response-based features known to predict relapse risk in childhood ALL, including those currently used and those likely to be used in the near future to risk-stratify therapy.

Early Response to Dexamethasone as Prognostic Factor: Result from Indonesian Childhood WK-ALL Protocol in Yogyakarta

Early response to treatment has been shown to be an important prognostic factor of childhood acute lymphoblastic leukemia (ALL) patients in Western studies. We studied this factor in the setting of a low-income province in 165 patients treated on Indonesian WK-ALL-2000 protocol between 1999 and 2006. Poor early response, defined as a peripheral lymphoblasts count of ≥1000/μL after 7 days of oral dexamethasone plus one intrathecal methotrexate (MTX), occurred in 19.4% of the patients. Poor responders showed a higher probability of induction failures compared to good responders (53.1% versus 23.3%, P < 0.01), higher probability of resistant disease (15.6% versus 4.5%, P = 0.02), shorter disease-free survival (P = 0.034; 5-year DFS: 24.9% ± 12.1% versus 48.6% ± 5.7%), and shorter event-free survival (P = 0.002; 5-year EFS: 9.7% ± 5.3% versus 26.3% ± 3.8%). We observed that the percentage of poor responders in our setting was higher than reported for Western countries with prednisone or prednisolone as the steroids. The study did not demonstrate a significant additive prognostic value of early response over other known risk factors (age and white blood cell count) for DFS and only a moderately added value for EFS.

Flow cytometric chemosensitivity assay as a predictive tool of early clinical response in acute lymphoblastic leukemia

BACKGROUND

Residual disease or rapidity of response to induction therapy is among the most powerful predictors of outcome in pediatric acute lymphoblastic leukemia (ALL).

METHOD

Utilizing a multiparameter flow cytometric chemosensitivity assay (FCCA), we studied the relationship between in vitro drug sensitivity of diagnostic leukemic blasts from 30 children with ALL and rapidity of response to induction therapy. We also analyzed the in vitro drug sensitivity of de novo leukemic blasts among various clinical subsets.

RESULTS

Compared to rapid early responders (RERs), slow early responders (SERs) had a significantly greater in vitro drug resistance to dexamethasone (DEX; P = 0.04) and prednisone (P = 0.05). The studies with all other drugs showed a non-significant trend with the SER having a higher in vitro drug resistance compared to the RER. Risk group stratified analyses indicated that in vitro resistance to asparaginase (ASP), DEX, and vincristine (VCR) were each significantly related to having very high risk ALL. Additionally, a significantly higher in vitro drug resistance to ASP and VCR was associated with unfavorable lymphoblast genetics and ultimate relapse.

CONCLUSION

Our data indicate that this FCCA is a potentially simple and rapid method to detect inherent resistance to initial ALL therapy very early in induction, thus allowing for treatment modification shortly thereafter.

Persistence of TEL-AML1 fusion gene as minimal residual disease has no additive prognostic value in CD 10 positive B-acute lymphoblastic leukemia: a FISH study

Objectives

We have analyzed t(12;21)(p13:q22) in an attempt to evaluate the frequency and prognostic significance of TEL-AML1 fusion gene in patients with childhood CD 10 positive B-ALL by fluorescence in situ hybridization (FISH). Also, we have monitored the prognostic value of this gene as a minimal residual disease (MRD).

Methods

All bone marrow samples of eighty patients diagnosed as CD 10 positive B-ALL in South Egypt Cancer Institute were evaluated by fluorescence in situ hybridization (FISH) for t(12;21) in newly diagnosed cases and after morphological complete remission as a minimal residual disease (MRD). We determined the prognostic significance of TEL-AML1 fusion represented by disease course and survival.

Results

TEL-AML1 fusion gene was positive in (37.5%) in newly diagnosed patients. There was a significant correlation between TEL-AML1 fusion gene both at diagnosis (r = 0.5, P = 0.003) and as a MRD (r = 0.4, P = 0.01) with favorable course. Kaplan-Meier curve for the presence of TEL-AML1 fusion at the diagnosis was associated with a better probability of overall survival (OS); mean survival time was 47 ± 1 month, in contrast to 28 ± 5 month in its absence (P = 0.006). Also, the persistence at TEL-AML1 fusion as a MRD was not significantly associated with a better probability of OS; the mean survival time was 42 ± 2 months in the presence of MRD and it was 40 ± 1 months in its absence. So, persistence of TEL-AML1 fusion as a MRD had no additive prognostic value over its measurement at diagnosis in terms of predicting the probability of OS.

Conclusion

For most patients, the presence of TEL-AML1 fusion gene at diagnosis suggests a favorable prognosis. The present study suggests that persistence of TEL-AML1 fusion as MRD has no additive prognostic value.

Prognostic factors for leukemic induction failure in children with acute lymphoblastic leukemia and outcome after salvage therapy: the FRALLE 93 study

PURPOSE

To identify prognostic factors and to evaluate the outcome of children with acute lymphoblastic leukemia (ALL) failure after induction therapy.

PATIENTS AND METHODS

Between June 1993 and December 1999, 1,395 leukemic children were included in the French Acute Lymphoblastic Leukemia 93 study.

RESULTS

Fifty-three patients (3.8%) had a leukemic induction failure (LIF) after three- or four-drug induction therapy. In univariate analysis, high WBC count (P = .001), mediastinal mass (P = .017), T-cell phenotype (T-ALL; P = .001), t(9;22) translocation (P = .001), and a slow early response (at day 8 and/or on day 21, P = .001) were predictive of LIF. The following three prognostic groups for LIF were identified by multivariate analysis: a low-risk group with B-cell progenitor (BCP) ALL without t(9;22) (odds ratio [OR] = 1), an intermediate-risk group with T-ALL and a mediastinal mass (OR = 7.4, P < .0001), and a high-risk group with BCP-ALL and t(9;22) or T-ALL without a mediastinal mass (OR = 28.4, P < .0001). Complete remission (CR) was subsequently obtained in 43 patients (81%). The 5-year overall survival (OS) rate of the 53 patients was 30% +/- 6%. The 5-year OS rate among allogeneic graft recipients, autologous graft recipients, and after chemotherapy were 30.4% +/- 9.6% (50% +/- 26% after genoidentical transplantation), 50% +/- 17.7%, and 41.7% +/- 14.2%, respectively (P = .18). Fourteen patients (26%) were still in first CR after a median of 83 months (range, 53 to 117 months).

CONCLUSION

Three risk categories for LIF in children with ALL were identified. Approximately one third of patients with LIF can be successfully treated with salvage therapy overall. Subsequent CR after LIF is mandatory for cure.

The changing pattern of "smart" flow cytometry (S-FC) to assist the cost-effective diagnosis of HIV, tuberculosis, and leukemias in resource-restricted conditions

There is a need to introduce cytometry into areas of the globe that have remained virtually untouched by modern laboratory medicine. With the demand to carry out tests on 100,000 s of individuals requiring antiretroviral therapy (ART), flow cytometry must remain simple and cost-effective - while being sustainable and industry supported as well as proven by quality assessment (QA). This outlook is referred to as "smart flow cytometry" (S-FC). There are five main areas where the power of S-FC is demonstrated. These are: (i) the use of CD45 to assist precise cell counting in blood and tissue samples; (ii) the primary CD4 gating to count CD4+ T cells in patients waiting for ART, including the combination (i) and (ii) in the panleucogating (PLG) protocol; (iii) monitoring of human immunodeficiency virus (HIV+) patients during ART by the decreasing levels of lymphocyte activation in a CD8/CD38 test - leading to economies of viral-load assays; (iv) in tuberculosis and HIV-TB coinfections the use of TB-antigen-stimulated cytokine-synthetic CD4+ T cells to identify active disease; and (v) the utilization of "minimal residual disease (MRD)-Lite" technology in patients 19 days after the start of antileukemic therapy to detect MRD. These methods of S-FC have been successfully introduced in "resource-restricted" countries with international and local QA.

Diagnostic pathways in acute leukemias: a proposal for a multimodal approach

Acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) each represent a heterogeneous complex of disorders, which result from diverse mechanisms of leukemogenesis. Modern therapeutic concepts are based on individual risk stratification at diagnosis and during follow-up. For some leukemia subtypes such as AML M3/M3v with t(15;17)/PML-RARA or Philadelphia-positive ALL targeted therapy options are available. Thus, optimal therapeutic conditions are based on exact classification of the acute leukemia subtype at diagnosis and are guided by exact and sensitive quantification of minimal residual disease during complete hematologic remission. Today, a multimodal diagnostic approach combining cytomorphology, multiparameter flow cytometry, chromosome banding analysis, accompanied by diverse fluorescence in situ hybridization techniques, and molecular analyses is needed to meet these requirements. As the diagnostic process becomes more demanding with respect to experience of personnel, time, and costs due to the expansion of methods, algorithms, which guide the diagnostic procedure from basic to more specific methods and which lead finally to a synopsis of the respective results, are essential for modern diagnostics and therapeutic concepts.

Intrathecal triple therapy decreases central nervous system relapse but fails to improve event-free survival when compared with intrathecal methotrexate: results of the Children's Cancer Group (CCG) 1952 study for standard-risk acute lymphoblastic leukemia, reported by the Children's Oncology Group

The Children's Cancer Group (CCG) 1952 clinical trial for children with standard-risk acute lymphoblastic leukemia (SR-ALL) compared intrathecal (IT) methotrexate (MTX) with IT triples (ITT) (MTX, cytarabine, and hydrocortisone sodium succinate [HSS]) as presymptomatic central nervous system (CNS) treatment. Following remission induction, 1018 patients were randomized to receive IT MTX and 1009 ITT. Multivariate analysis identified male sex, hepatomegaly, CNS-2 status, and age younger than 2 or older than 6 years as significant predictors of isolated CNS (iCNS) relapse. The 6-year cumulative incidence estimates of iCNS relapse are 3.4% +/- 1.0% for ITT and 5.9% +/- 1.2% for IT MTX; P = .004. Significantly more relapses occurred in bone marrow (BM) and testicles with ITT than IT MTX, particularly among patients with T-cell phenotype or day 14 BM aspirate containing 5% to 25% blasts. Thus, the estimated 6-year event-free survivals (EFS) with ITT or IT MTX are equivalent at 80.7% +/- 1.9% and 82.5% +/- 1.8%, respectively (P = .3). Because the salvage rate after BM relapse is inferior to that after CNS relapse, the 6-year overall survival (OS) for ITT is 90.3% +/- 1.5% versus 94.4% +/- 1.1% for IT MTX (P = .01). It appears that ITT improves presymptomatic CNS treatment but does not improve overall outcome.

A simplified flow cytometric assay identifies children with acute lymphoblastic leukemia who have a superior clinical outcome

Bone marrow normal lymphoid progenitors (CD19+, CD10+, and/or CD34+) are exquisitely sensitive to corticosteroids and other antileukemic drugs. We hypothesized that, in patients with B-lineage acute lymphoblastic leukemia (ALL), cells with this phenotype detected early in treatment should be leukemic rather than normal. We therefore developed a simple and inexpensive flow cytometric assay for such cells and prospectively applied it to bone marrow samples collected on day 19 from 380 children with B-lineage ALL. In 211 patients (55.5%), these cells represented 0.01% or more of the mononuclear cells; results correlated remarkably well with those of more complex flow cytometric and molecular minimal residual disease (MRD) evaluations. Among 84 uniformly treated children, the 10-year incidence of relapse or remission failure was 28.8% +/- 7.1% (SE) for the 42 patients with 0.01% or more leukemic cells on day 19 detected by the simplified assay versus 4.8% +/- 3.3% for the 42 patients with lower levels (P = .003). These assay results were the strongest predictor of outcome, even after adjustment for competing clinicobiologic variables. Thus, this new assay would enable most treatment centers to identify a high proportion of children with ALL who have an excellent early treatment response and a high likelihood of cure.

Risk of Adverse Events After Completion of Therapy for Childhood Acute Lymphoblastic Leukemia

Purpose

We studied the frequency, causes, and predictors of adverse events in children with acute lymphoblastic leukemia (ALL) who had completed treatment on contemporary clinical protocols between 1984 and 1999. Our goal was to use the information to further refine therapy and advance cure rates.

Methods

Cumulative incidence functions of any post-treatment failure or any post-treatment relapse were estimated by the method of Kalbfleisch and Prentice and compared with Gray's test. The Cox proportional hazards model was used to identify independent prognostic factors.

Results

Of the 827 patients who completed all treatment while in initial complete remission, 134 patients subsequently had major adverse events, including 90 leukemic relapses, 40 second malignancies, and four deaths in remission. The cumulative incidence of any adverse event was 14.0% ± 1.2% (SE) at 5 years and 16.9% ± 1.4% at 10 years. The risk of any leukemic relapse was 10.0% ± 1.1% at 5 years and 11.4% ± 1.2% at 10 years. Male sex was the only independent predictor of relapse (hazard ratio, 1.74; 95% CI, 1.11 to 2.74; P = .02).

Conclusion

Further treatment refinements for children with ALL should aim not only to decrease the leukemic relapse rate, but also to reduce the risk of development of second malignancies.

Prognostic Value of Early Response to Treatment Combined with Conventional Risk Factors in Pediatric Acute Lymphoblastic Leukemia

To determine useful prognostic factors in treating childhood acute lymphoblastic leukemia (ALL), we correlated conventional risk factors and bone marrow response 14 days after induction chemotherapy. Our study included 116 precursor B-cell (n = 104) and T-cell (n = 12) ALL patients treated with our protocol between 1988 and 1999. The patients were classified into 3 initial risk groups on the basis of conventional risk factors (56 in the low-risk, 33 in the high-risk, and 27 in the very high-risk groups). All patients received similar systemic chemotherapy regimens before the evaluation of their bone marrow on day 14. We evaluated the marrow of 69 patients as M1 (less than 5% blasts), 25 as M2 (5%-25% blasts), and 22 as M3 (more than 25% blasts). Although all patients attained an initial complete remission (CR), relapse was noted in 33 of the 116 patients, and 15 patients died. All of the M1 marrow patients, irrespective of the initial risk group, showed the best event-free survival rate (85.1% +/- 3 4.4%), the lowest relapse rate (14.5%), and the highest attainment of a second CR (100%); they were defined as the new R1 prognostic group. The low-risk patients with M2 or M3 marrow (R2 group) had a relatively high relapse rate, but all of these relapsed patients were treated successfully with subsequent therapy. High- or very high-risk patients with M2 or M3 marrow (R3 group) had the worst prognosis. Our new prognostic definition (R1, R2, R3) incorporating day 14 marrow findings is useful to tailor early-phase treatments for better therapeutic results in childhood ALL.

The biology and therapy of adult acute lymphoblastic leukemia

BACKGROUND

Much progress has been made in understanding the biology of acute lymphoblastic leukemia (ALL). This has translated into the recognition of several subgroups of ALL and the institution of risk-adapted therapies. New therapies are emerging based on the definition of specific cytogenetic-molecular abnormalities.

METHODS

A review from the English literature, including original articles and related reviews from Medline (Pubmed) and abstracts based on publication of meeting material, was performed.

RESULTS

Changes in the pathologic classification of ALL have led to therapeutic consequences. Adaptation of successful treatment strategies in children with ALL has resulted in similar complete response rates in adults. Prognosis has especially improved in mature-B-cell and T-lineage ALL. The role of tyrosine kinase inhibitors in Philadelphia chromosome-positive ALL was evaluated in the current study. However, regardless of the ALL subgroup, long-term survival of adults is still inferior to that in children.

CONCLUSIONS

Intense clinical and laboratory research is attempting to close the gap in outcome between children and adults with ALL. Investigations are focusing on 1) refinement of the basic treatment stratagem of induction, consolidation, and maintenance; 2) expansion of risk-based, subgroup-oriented therapies; 3) assessment of minimal residual disease, its impact on disease recurrence, and its practical implications in clinical practice; 4) salvage strategies; 5) the role of stem cell transplantation in ALL; and 6) the development of new drugs based on a better understanding of disease biology.

The dose related effect of steroids on blast reduction rate and event free survival in children with acute lymphoblastic leukemia

We examined the effect of high-dose methylprednisolone (HDMP) on blast reduction rate and compared it to conventional dose steroid treatment, administered during the first 7+ days of the induction remission period in patients with acute lymphoblastic leukemia (ALL). In our previous randomized study, the event free survival (EFS) was found to be higher in patients treated with HDMP (Group B) than in patients treated with a conventional dose of steroids (Group A). We used the chemotherapy protocol for ALL patients according to the St Jude Total XI study group. Medical records of all 194 patients who achieved complete remission were reviewed to determine the absolute blast count (ABC) in peripheral blood smears from day 0 of treatment until day 8. A target response of 1,000 blast/mm3 was employed. The time in which ABC remained > or = 1,000/mm3 and the EFS rates were assessed in group A (n = 44) and B (n = 51) of high risk patients. Group A and B patients were branched to chemotherapy schedules (A1, B1: steroid + vincristine + daunorubicine + intrathecal + 3 doses L-asparaginase; A2, B2: steroid + vincristine + daunorubicine + intrathecal; A3, B3: only steroid monotherapy). Number of patients from whom the ABC remained > or = 1,000/mm3 during all 7 days of induction treatment and the median number of days for blasts to reach the target level were significantly lower in group B1 than A1 (p < 0.05), concordantly the 8-year EFS was higher in group B1 (p = 0.01). In comparison of the subgroups, results of A2 and A3 were worse than of group B2 and B3. These findings strongly suggest that the effects of HDMP on blast cytoreduction and EFS are more potent than conventional dose steroids.

Post-induction residual disease in translocation t(12;21)-positive childhood ALL

BACKGROUND

t(12;21)(p1 3;q22), the most frequent chromosomal translocation found in childhood acute lymphoblastic leukemia (ALL), occurs in approximately 25% of B-lineage ALL cases and has been claimed to carry a good prognosis.

PROCEDURE

As part of the Nordic Society of Pediatric Hematology and Oncology (NOPHO) ALL-MRD 95 study, which includes children from Iceland, Norway, and Denmark diagnose d with ALL, patients were screened for the presence of t(12; 21) by reverse transcriptase-polymerase chain reaction (RT-PCR) at diagnosis, and their residual disease was quantified after 4 weeks of induction therapy (prednisolone, vincristine, doxorubicin, i.t. methotrexate) by a competitive, clone-specific, semi-nested PCR analysis.

RESULTS

Among 96 children diagnosed with ALL, and quantified for post induction residual disease, 32 were t(12;21)-positive. The median residual disease was similar for B-precursor ALL patients with and without t(12;21) (0.009 vs. 0.03%, P = 0.12).

CONCLUSIONS

Al though patients with t(12;21)-positive ALL have been claimed to have a good outcome, these data indicate that this does not reflect a high sensitivity to prednisolone, vincristine, and doxorubicin given during induction therapy.

Persistence of lymphoblasts in bone marrow on day 15 and days 22 to 25 of remission induction predicts a dismal treatment outcome in children with acute lymphoblastic leukemia

We determined the prognostic importance of morphologically identifiable persistent disease at day 15 and days 22 to 25 of remission induction in childhood acute lymphoblastic leukemia (ALL). Among 546 patients entered on 2 consecutive protocols, 397 patients had evaluable bone marrow (BM) examinations on day 15 (+/- 1 day) and 218 on days 22 to 25 (+/- 1 day). Fifty-seven patients (14%) had persistent lymphoblasts (> or = 1%) in the BM on day 15 and 27 patients (5.5%) had persistent lymphoblasts on days 22 to 25. The 5-year event-free survival (EFS) was significantly worse for patients with lymphoblasts on day 15 (40% +/- 6%) or on days 22 to 25 (4% +/- 3%) as compared to those without lymphoblasts on these dates (78% +/- 2% and 76% +/- 2%, respectively, P <.001 for both comparisons). A worse prognosis was observed even for patients with a low percentage of lymphoblasts (ie, 1%-4%) at either day 15 (5-year EFS = 56% +/- 8%) or days 22 to 25 (5-year EFS = 0%) compared to those without morphologically identifiable persistent lymphoblasts at these times (P <.001 for both comparisons). The prognostic impact of persistent lymphoblasts on both dates remained significant after adjusting for other known risk factors, including treatment protocol, age, white blood cell count, DNA index, cell lineage, and central nervous system status, and National Cancer Institute/Rome criteria simultaneously. Hence, persistence of lymphoblasts (even 1%-4%) on day 15 of remission induction was associated with a poor prognosis and on days 22 to 25 signified a particularly dismal outcome; these very high-risk patients require novel or more intensive therapy to improve outcome.

Prognostic importance of measuring early clearance of leukemic cells by flow cytometry in childhood acute lymphoblastic leukemia

Early clearance of leukemic cells is a favorable prognostic indicator in childhood acute lymphoblastic leukemia (ALL). However, identification of residual leukemic cells by their morphologic features is subjective and lacks sensitivity. To improve estimates of leukemia clearance, we applied flow cytometric techniques capable of detecting 1 leukemic cell in 10,000 or more normal cells and prospectively measured residual leukemia in bone marrow samples collected on day 19 of remission-induction chemotherapy from 248 children with newly diagnosed ALL. In 134 samples (54.0%), we identified at least 0.01% leukemic cells (0.01%-< 0.1% in 51 samples [20.6%], 0.1%-< 1% in 36 [14.5%], and > or = 1% in 47 [19.0%]). Among 110 children treated within a single chemotherapy program, the 5-year mean +/- SE cumulative incidence of relapse or failure to achieve remission was 32.2% +/- 6.5% for the 59 patients with 0.01% residual leukemic cells or greater on day 19 and 6.0% +/- 3.4% for the 51 patients with less than 0.01% leukemic cells (P <.001). The prognostic value of day-19 bone marrow status defined by flow cytometry was superior to that defined by morphologic studies and remained significant after adjustment for other clinical and biologic variables. Lack of detectable leukemic cells on day 19 was more closely associated with relapse-free survival than was lack of detectable residual disease at the end of remission induction (day 46). Thus, approximately half of the children with ALL achieve profound clearance of leukemic cells after 2 to 3 weeks of remission-induction chemotherapy, and these patients have an excellent treatment outcome.

Intermediate-dose methotrexate and intravenous 6-mercaptopurine chemotherapy for children with acute lymphoblastic leukemia who did not respond to initial induction therapy

PURPOSE

To determine the complete remission rate of children with acute lymphoblastic leukemia (ALL) who were not induced into remission by initial therapy, when subsequently treated with intermediate-dose methotrexate and intravenous 6-mercaptopurine.

PATIENTS AND METHODS

Children with B-precursor ALL who did not achieve initial remission after 4 or 6 weeks of standard three- or four-drug induction chemotherapy were entered on study. Therapy consisted of three doses at weekly intervals of methotrexate 1,000 mg/m2 over 24 hours followed by 6-mercaptopurine 1,000 mg/m2 over 8 hours 20 minutes. Patients achieving a partial remission could receive two additional weekly courses of methotrexate and 6-mercaptopurine. Initially, patients received weekly intrathecal chemotherapy, but the study was amended to include intrathecal therapy only at week 1.

RESULTS

Nineteen patients were entered on study. All were evaluable for toxicity and response. There were seven complete remissions, four partial remissions, six patients with no response, and two children with progressive disease, for an overall complete remission rate of 37%. One patient was removed from the study after the second course of methotrexate and 6-mercaptopurine because of renal failure. Two patients had neurologic toxicity resulting in a study amendment. No patients subsequently experienced neurologic toxicity.

CONCLUSIONS

Intermediate-dose intravenous methotrexate and intravenous 6-mercaptopurine can induce remission in some patients with ALL who experience initial induction failure. Features predicting complete remission, however, could not be identified.

Precise quantification of minimal residual disease at day 29 allows identification of children with acute lymphoblastic leukemia and an excellent outcome

The postinduction level of minimal residual disease (MRD) was quantified with a competitive polymerase chain reaction (PCR) technique in 104 children with acute lymphoblastic leukemia (ALL) diagnosed between June 1993 and January 1998 and followed for a median of 4.2 years. A significant correlation was found between the MRD level on day 15 (D15) and day 29 (D29) after the start of induction therapy (r(s) = 0.70, P <.0001). The 15 patients with T-cell disease had higher D29 MRD than those with B-lineage ALL (P =.01). Age was positively related to D29 MRD (r(s) = 0.32, P =.001). The 16 patients who had a relapse had higher D15 and D29 MRD levels than the patients who stayed in remission (median levels D15, 1% versus 0.1%, P =.03; D29, 0.4% versus 0.01%, P =.0001). No patients with a MRD level less than 0.01% on D29 have so far had a relapse, whereas the 7-year probability of event-free survival for patients with higher MRD levels was 0.52 (P =.0007). The group of patients with a D29 MRD less than 0.01% included patients with T-cell disease, white blood cell count more than 50 x 10(9)/L at diagnosis, or age 10 years or older, and could not be identified by up-front criteria. The best-fit Cox model to predict the risk of relapse included D29 MRD (P =.004) and age (P =.009). These findings indicate that with the present treatment protocol MRD quantification at an early stage of therapy identifies patients with a very low risk of relapse. Further trials are needed to reveal whether such patients with D29 MRD less than 0.01% can be cured with less intensive chemotherapy, which would reduce the risk of serious late effects as well as the costs of therapy.

Early response to chemotherapy as a prognostic factor in childhood acute lymphoblastic leukaemia: a methodological review

Published studies of the prognostic value of the early response to induction treatment in childhood acute lymphoblastic leukaemia (ALL) were analysed. Three criteria were used to judge the early treatment response: persistence of peripheral blasts (PPB) or of bone marrow blasts (PBMB) during induction therapy and minimal residual disease (MRD) after completion of induction therapy. Studies with more than 50 patients, published between 1980 and 2000, were reviewed. Among 13 659 distinct articles published on ALL, we identified only 43 applicable studies. Within- and between-laboratory variations were evaluated in only one study. Treatment modalities differed among, and sometimes within, studies. The cut-off points used in the statistical analyses were never discussed, and in many studies appeared to be selected after multiple tests. The proportion of missing data was > 30% in almost all studies of MRD, as a result of technical difficulties and not missing samples. PPB and PBMB were associated with shorter survival in, respectively, 13 out of 14 and 15 out of 16 studies. Detection of MRD was associated with poor outcome in 12 of the 13 studies. Because none of the parameters used to measure the early response to induction therapy for childhood ALL have been properly assessed as prognostic factors, we conclude that they should be considered only as candidate prognostic indicators pending more thorough studies.

A comparison of early intensive methotrexate/mercaptopurine with early intensive alternating combination chemotherapy for high-risk B-precursor acute lymphoblastic leukemia: a Pediatric Oncology Group phase III randomized trial

A prospective, randomized multicenter study was performed to evaluate the relative efficacy of two different concepts for early intensive therapy in a randomized trial of children with B-precursor acute lymphoblastic leukemia (ALL) at high risk (HR) for relapse. Four hundred and ninety eligible children with HR-ALL were randomized on the Pediatric Oncology Group (POG) 9006 phase III trial between 7 January 1991 and 12 January 1994. After prednisone (PDN), vincristine (VCR), asparaginase (ASP) and daunorubicin (DNR) induction, 470 patients received either 12 intensive parenteral treatments of intermediate dose (1 g/m2 each) methotrexate (MTX) and mercaptopurine (MP) over 24 weeks (regimen A) or 12 intensive course of alternating myelosuppressive drug combinations given over 30 weeks (regimen B). These drug combinations included MTX/MP, teniposide (VM-26)/cytosine arabinoside (AC) and VCR/PDN/DNR/AC/ASP. Central nervous system (CNS) prophylaxis was age-adjusted triple intrathecal chemotherapy. Patients with CNS disease at diagnosis were treated with craniospinal irradiation after the intensive phase. Continuation was standard doses of MTX and MP for 2 years. This trial was closed early because of an apparent early difference favoring regimen B. Results show that 470 patients achieved remission (97%). Two hundred and thirty two were randomized to regimen A and 238 to regimen B. The estimated 4-year event-free survival (EFS) for patients treated with regimen A is 61.6 % (s.e. = 3.3%) and with regimen B is 69.4% (s.e. = 3.1%), P = 0.091. Toxicities were more frequent on regimen B. In conclusion, for children with B-precursor ALL at high risk to relapse, early intensification with myelosuppressive combination chemotherapy was more toxic but produced no significant difference in EFS when compared to those treated with parenteral methotrexate and mercaptopurine.

Post-induction residual leukemia in childhood acute lymphoblastic leukemia quantified by PCR correlates with in vitro prednisolone resistance

Most prognostic factors in childhood acute lymphoblastic leukemia (ALL) are informative for groups of patients, whereas new approaches are needed to predict the efficacy of chemotherapy for the individual patient. The residual leukemia following 4 weeks of induction therapy with prednisolone, vincristine, doxorubicin and i.t. methotrexate and the in vitro resistance to prednisolone, vincristine, and doxorubicin were measured in 30 boys and 12 girls with B (n = 34) or T lineage (n = 8) ALL. The residual leukemia was quantified after 2 (MRD-D15, n = 29) and 4 weeks (MRD-PI, n = 42) of induction therapy with a precise and reproducible clone-specific PCR technique. The median MRD-D15 and MRD-PI were 0.50% (75% range 0.0088.1%) and 0.014% (75% range 0.001-2.0%), respectively, and these levels correlated significantly (n = 29, rs = 0.75, P < 0.001). Both the MRD-D15 and the MRD-PI were related to the age of the patient (MRD-D15: rs= 0.48, P= 0.009; MRD-PI: rs = 0.45, P = 0.003). Patients with T lineage ALL had higher MRD-PI than those with B lineage ALL (median MRD-PI: 0.5% vs 0.01%, P = 0.05). The median LC50 (concentration lethal to 50% of cells) for prednisolone was 2.3 microg/ml (75% range 0.05-668). Both MRD-D15 and MRD-PI correlated significantly with the in vitro resistance to prednisolone (MRD-D15: rs = 0.41, P = 0.03; MRD-PI: rs = 0.39, P = 0.01); but not to in vitro vincristine or doxorubicin resistance. The correlations between MRD and in vitro prednisolone resistance were even more pronounced when B cell precursor and T cell leukemia were analyzed separately (B cell precursor ALL: MRD-PI vs prednisolone LC50: n = 33, rs = 0.47, P = 0.006; T cell ALL: MRD-PI vs prednisolone resistance: n = 8, rs = 0.84, P = 0.009). After a median follow-up of 5.0 years (75% range 3.2-6.9) eight patients have relapsed. All of the 21 patients with a MRD-PI < or =0.5% and a prednisolone LC50 < or =10 microg/ml have remained in remission whereas the 7 year event-free survival for the remaining 20 patients was 0.45 +/- 0.16 (P= 0.002) Prospective studies in childhood ALL are needed to clarify whether combined monitoring of in vitro drug resistance and residual leukemia early during chemotherapy could offer new ways to classify patients and stratify the intensity of therapy.

Determinants of outcome after intensified therapy of childhood lymphoblastic leukaemia: results from Medical Research Council United Kingdom acute lymphoblastic leukaemia XI protocol

The single most important prognostic determinant in childhood acute lymphoblastic leukaemia (ALL) is effective therapy and changes in therapy may influence the significance of other risk factors. The effect of intensified therapy on the importance of currently recognized phenotypic and genotypic determinants of outcome was assessed in 2090 children enrolled on the Medical Research Council United Kingdom acute lymphoblastic leukaemia XI (MRC UKALL XI) protocol. Treatment allocation was not determined by risk factors. Multivariate analysis confirmed the dominant influence on prognosis of age, sex and presenting white cell count (WCC). After allowing for these features, blast karyotype, d 8 marrow blast percentage and remission status at the end of induction therapy were the only remaining significant predictors of outcome. Organomegaly, haemoglobin concentration, French--American--British type, body mass index, presence of central nervous system disease at diagnosis, immunophenotype and presence of TEL/AML1 fusion gene (examined in a subset of 659 patients) either had no significant effect on outcome or were significant only in univariate analysis. Among karyotype abnormalities with an independent influence on prognosis, high hyperdiploidy (> 50 chromosomes) was shown to be favourable, whereas near haploidy (23--29 chromosomes), presence of the Philadelphia chromosome, t(4;11) and abnormalities affecting the short arm of chromosome 9 [abn (9p)] were adverse risk factors. Early responders to therapy, determined by residual marrow infiltration after 8 d of induction therapy, had a good outcome, while the small proportion of patients who did not achieve a complete remission by the end of induction therapy had a poor outcome. A third block of late intensification was shown to improve event-free survival by 8% at 5 years. The effect of these risk factors was not significantly different between those randomized to the third intensification block and those not randomized to a third block.

Slow disappearance of peripheral blood blasts is an adverse prognostic factor in childhood T cell acute lymphoblastic leukemia: a Pediatric Oncology Group study

The rapidity of response to induction therapy is emerging as an important prognostic factor in children and adolescents with acute lymphoblastic leukemia (ALL). We studied the relationship between rapidity of reduction in peripheral blood blast count and treatment outcome in children with T cell ALL (T-ALL). Initial systemic chemotherapy included prednisone, vincristine, doxorubicin and cyclophosphamide. A Cox analysis evaluated the correlation between the length of time that the peripheral blood absolute blast count (ABC) remained above 1000/mm3 following the start of treatment and event-free survival (EFS). Data were available for 281 patients. Patients for whom the ABC remained >1000/mm3 for 3 or more days following administration of intensive therapy had an estimated 5-year EFS of 34.2% (s.e. = 7.2) vs 58.3% (3.5) for those whose ABC was <1000/mm3 within 0-2 days, with a hazard ratio (HR) of failure of 2.03 (95% CI = 1.35-3.06, P < 0.001) for the slower responding patients. Pre-treatment of some type (usually with prednisone) occurred in 128 patients (average duration 1.7 days). When this was accounted for, patients with an ABC >1000/mm3 for 5 or more days following the start of treatment of any kind had a HR for failure of 2.27 (95% CI = 1.38-3.72, P < 0.001) compared to those responding within 0-4 days. Inclusion of other clinical and biological factors in a multivariate analysis did not alter the prognostic importance of slower blast clearance. Pediatric patients with T-ALL who have a circulating blast count >1000/mm3 at diagnosis and a relatively slower response to initial treatment are at increased risk of treatment failure. Rapidity of response may therefore be a clinically useful prognostic factor for patients with T-ALL.

Use of recombinant human granulocyte colony-stimulating factor to increase chemotherapy dose-intensity: a randomized trial in very high-risk childhood acute lymphoblastic leukemia

PURPOSE

To determine whether the use of a recombinant human granulocyte colony-stimulating factor ([G-CSF] lenogastrim) can increase the chemotherapy dose-intensity (CDI) delivered during consolidation chemotherapy of childhood acute lymphoblastic leukemia (ALL).

PATIENTS AND METHODS

Sixty-seven children with very high-risk ALL were randomized (slow early response to therapy, 55 patients; translocation t(9;22) or t(4;11), 12 patients). Consolidation consisted of six courses of chemotherapy; the first, third, and fifth courses were a combination of high-dose cytarabine, etoposide, and dexamethasone (R3), whereas the second, fourth, and sixth courses included vincristine, prednisone, cyclophosphamide, doxorubicin, and methotrexate (COPADM). G-CSF was given after each course, and the next scheduled course was started as soon as neutrophil count was > 1 x 10(9)/L and platelet count was > 100 x 10(9)/L. CDI was calculated using the interval from day 1 of the first course to hematologic recovery after the fifth course (100% CDI = 105-day interval).

RESULTS

CDI was significantly increased in the G-CSF group compared with the non-G-CSF group (mean +/- 95% confidence interval, 105 +/- 5% v 91 +/- 4%; P <.001). This higher intensity was a result of shorter post-R3 intervals in the G-CSF group, whereas the post-COPADM intervals were not statistically reduced. After the R3 courses, the number of days with fever and intravenous antibiotics and duration of hospitalization were significantly decreased by G-CSF, whereas reductions observed after COPADM were not statistically significant. Duration of granulocytopenia was reduced in the G-CSF group, but thrombocytopenia was prolonged, and the number of platelet transfusions was increased. Finally, the 3-year probability of event-free survival was not different between the two groups.

CONCLUSION

G-CSF can increase CDI in high-risk childhood ALL. Its effects depend on the chemotherapy regimen given before G-CSF administration. In our study, a higher CDI did not improve disease control.

Rapid molecular response during early induction chemotherapy predicts a good outcome in childhood acute lymphoblastic leukemia

Early response to therapy is an independent prognostic factor in childhood acute lymphoblastic leukemia. Although most patients have rapid early responses, as detected by morphology, 15% to 20% of patients have relapses. The authors evaluated residual disease by molecular methods on day 15 of minimal residual disease (MRD) therapy and compared these data with their recently established MRD-based risk stratification, defined by MRD levels 5 weeks after induction treatment and before consolidation. All 68 children treated according to current Berlin-Frankfurt-Münster (BFM) protocols went into morphologically complete remission after induction. There was a significant difference in outcome between children with rapid disease clearance and those with high levels of day-15 MRD (P = .035). Among patients with high levels of day-15 MRD, only the MRD-based risk stratification was predictive of the outcome. All patients with negative or low day-15 MRD had excellent prognoses and were in the MRD-based low-risk group. Thus, after only 2 weeks of treatment, the authors were able to identify a patient population of 20% who may benefit from the least intensive treatment.

Competitive PCR for quantification of minimal residual disease in acute lymphoblastic leukaemia

A very precise and reproducible polymerase chain reaction (PCR) method was developed in order to quantify minimal residual disease (MRD) in children with acute lymphoblastic leukaemia (ALL). A clone-specific competitor was constructed by introducing a restriction site in a PCR product identical to parts of the highly specific rearranged T-cell receptor delta (TCR-delta), T-cell receptor gamma (TCR-gamma), or immunoglobulin heavy chain (IgH) genes of the malignant clone. Using primers located externally to the restriction site the competitor and the DNA from the malignant clone will be amplified under identical conditions. After restriction enzyme cleavage, the PCR products originating from the competitor and the malignant clone can be distinguished by size in a gel electrophoresis step and the amount of residual disease can be determined. The method is very sensitive with a detection limit of at least one malignant cell in 10(5) normal cells. This method may be used for treatment stratification based on the early response to antileukaemic therapy.

Prednisone Response Is the Strongest Predictor of Treatment Outcome in Infant Acute Lymphoblastic Leukemia

To define prognostic factors in infant acute lymphoblastic leukemia (ALL), the outcome of 106 infants (age ≤12 months) during 3 consecutive multicenter trials of the Berlin-Frankfurt-Münster group (ALL-BFM 83, 86, and 90) was retrospectively analyzed according to presenting features and early in vivo response to prednisone. The prednisone response was defined as the cytoreduction (number of blood blasts per microliter at day 8) to a 7-day prednisone prephase and 1 intrathecal dose of methotrexate on day 1. Prednisone good responder (PGR; <1,000 blasts/μL) received conventional therapy and prednisone poor responder (PPR; ≥1,000 blasts/μL) received intensified therapy. Infant ALL was characterized by a high incidence of a white blood cell count greater than 100 × 103/μL (57%), central nervous system leukemia (24%), lack of CD10 expression (59%), 11q23 rearrangement (49%) including the translocation t(4;11) (29%), and a comparatively high proportion of PPR (26%), which were all significantly associated with inferior outcome by univariate analysis. The estimated probability for an event-free survival at 6 years (pEFS) was by far better for PGR compared with PPR, who had a dismal prognosis despite intensified treatment (pEFS, 53% ± 6%v 15% ± 7%, P = .0001). Infant PGR, who were less than 6 months of age (n = 40), lacked CD10 expression (n = 43), and/or had an 11q23 rearrangement (n = 17) fared significantly better compared with corresponding PPR, as indicated by a pEFS of 44% ± 8%, 49% ± 8%, and 41% ± 12%, respectively. In multivariate analysis, PPR was the strongest adverse prognostic factor (relative risk, 3.3; 95% confidence interval, 1.9 to 5.8; P< .0001). Infants with PGR, comprising a major subgroup (74%) among infants, might successfully be treated with conventional therapy, whereas PPR require new therapeutic strategies, including early treatment intensification or bone marrow transplantation in first remission.

Prednisone Response Is the Strongest Predictor of Treatment Outcome in Infant Acute Lymphoblastic Leukemia

To define prognostic factors in infant acute lymphoblastic leukemia (ALL), the outcome of 106 infants (age ≤12 months) during 3 consecutive multicenter trials of the Berlin-Frankfurt-Münster group (ALL-BFM 83, 86, and 90) was retrospectively analyzed according to presenting features and early in vivo response to prednisone. The prednisone response was defined as the cytoreduction (number of blood blasts per microliter at day 8) to a 7-day prednisone prephase and 1 intrathecal dose of methotrexate on day 1. Prednisone good responder (PGR; &lt;1,000 blasts/μL) received conventional therapy and prednisone poor responder (PPR; ≥1,000 blasts/μL) received intensified therapy. Infant ALL was characterized by a high incidence of a white blood cell count greater than 100 × 103/μL (57%), central nervous system leukemia (24%), lack of CD10 expression (59%), 11q23 rearrangement (49%) including the translocation t(4;11) (29%), and a comparatively high proportion of PPR (26%), which were all significantly associated with inferior outcome by univariate analysis. The estimated probability for an event-free survival at 6 years (pEFS) was by far better for PGR compared with PPR, who had a dismal prognosis despite intensified treatment (pEFS, 53% ± 6%v 15% ± 7%, P = .0001). Infant PGR, who were less than 6 months of age (n = 40), lacked CD10 expression (n = 43), and/or had an 11q23 rearrangement (n = 17) fared significantly better compared with corresponding PPR, as indicated by a pEFS of 44% ± 8%, 49% ± 8%, and 41% ± 12%, respectively. In multivariate analysis, PPR was the strongest adverse prognostic factor (relative risk, 3.3; 95% confidence interval, 1.9 to 5.8; P&lt; .0001). Infants with PGR, comprising a major subgroup (74%) among infants, might successfully be treated with conventional therapy, whereas PPR require new therapeutic strategies, including early treatment intensification or bone marrow transplantation in first remission.

Induction failure in acute lymphoblastic leukemia of childhood

BACKGROUND

Although it is widely accepted that failure to achieve complete remission (CR) portends a poor prognosis in childhood acute lymphoblastic leukemia (ALL), there is variability in the precise definition of induction failure and, to the authors' knowledge, few published data exist regarding the outcome of patients who are slow to achieve CR.

METHODS

Between 1987-1995, 774 children with ALL were treated on 2 consecutive protocols and were evaluable to assess the time required to attain CR. The authors compared presenting characteristics and outcomes of patients based on their remission status after 1 month of induction chemotherapy: CR (n = 656), protracted hypoplasia (low peripheral blood counts and/or hypocellular marrow) (n = 95), and persistent leukemia (M2 or M3 bone marrow and/or evidence of extramedullary leukemia) (n = 23). The median follow-up was 5.2 years.

RESULTS

Presenting features that predicted persistent leukemia included a leukocyte count > 100,000/mm3 and T-cell phenotype. Approximately 91% of patients with persistent leukemia and 100% with protracted hypoplasia eventually achieved CR. The 5-year event free survival (EFS) (95% confidence intervals [95% CI] in parentheses) for patients with persistent leukemia after 1 month was 16% (95% CI, 0%, 31%), which was significantly worse (P < 0.001) than that for those who achieved CR within 1 month (5-year EFS, 82%; 95% CI, 79%, 86%) and that for those with protracted hypoplasia (5-year EFS, 79%; 95% CI, 70%, 87%). For patients with persistent leukemia, there was no significant difference in survival based on bone marrow status (M2 or M3) after 1 month or on the number of induction cycles received before achieving CR.

CONCLUSIONS

Patients with persistent leukemia at the end of 1 month of therapy have a dismal prognosis, regardless of when they subsequently achieve CR. More intensive and/or novel therapies should be considered for this subset of patients.

Clinical importance of speed of response to therapy in childhood lymphoblastic leukaemia

Speed of response to therapy predicts outcome in childhood lymphoblastic leukaemia. This observation has been made studying both blood and bone marrow in children on widely differing treatment regimens from the 1970s to the present day. It appears to be independent of other classical prognostic factors such as age and diagnostic white cell count. Currently some major collaborative groups are using the rate of initial disease clearance to risk-stratify subsequent therapy and this practice may increase. The best way to measure the rate of disease clearance remains to be defined. Watching disappearance of peripheral blood blasts is the least invasive method but possibly the least sensitive. Molecular quantitation of minimal residual disease (MRD) after achievement of conventional remission is much more sensitive but less specific. It cannot be applied to all patients and is costly and time consuming. The degree of marrow infiltration remaining after 7 or 14 days may fall between the two but is often difficult to estimate reliably and reproducibly due to technical limitations. The three techniques may reflect response to therapy in a way slightly different from each other and may not be direct correlates. The best compromise may be to use all three but to reserve MRD study only for those who clear their blood and bone marrow after 7 days.

Critical study of prognostic factors in childhood acute lymphoblastic leukaemia: differences in outcome are poorly explained by the most significant prognostic variables. Fralle group. French Acute Lymphoblastic Leukaemia study group

We determined the proportion of survival variability explained by the usual prognostic factors in childhood acute lymphoblastic leukaemia (ALL) during a prognostic study of 1552 patients enrolled in three consecutive Fralle group protocols (Fralle 83, Fralle 87 and Fralle 89). The event-free survival rates at 5 years were 54.8% (SD 1.9), 43.1%) (SD 2.7) and 55.6% (SD 2.2), respectively. In the univariate analysis the following variables were predictive of poor outcome: male gender, elevated leucocytosis (> 50 x 10(9)/l), circulating blastosis. haemoglobin >12 g/dl, platelet count <100 x 10(9)/l, age under 1 year or over 9 years, enlarged mediastinum, nodes, spleen and liver, T phenotype, absence of CD10+ cells; testicular and meningeal involvement, poor response to induction therapy (CCSG M3), and LDH >400 U/l. Among the cytogenetic features, hyperdiploidy had a protective effect, whereas hypodiploidy, translocation and other structural abnormalities had a negative influence, particularly in cases of t(9;22) or t(4;11). Multivariate analysis summarized the prognostic information in terms of four variables: age, gender, leucocytosis and cytogenetic features. Missing data had little influence on the results. However, despite their significance in the multivariate analysis, these four variables each had very low predictive power (1.1% for gender, 2.0% for age, 3.5% for leucocytosis, and 1.6% for cytogenetic features). Thus, the most significant prognostic factors in childhood ALL each explain no more than 4% of the variability in prognosis. This may explain the disappointing practical value of these factors and underlines the need for prognostic tools in childhood ALL.

Multiple drug resistance mediated by P-glycoprotein is not a major factor in a slow response to therapy in childhood ALL

In childhood acute lymphoblastic leukemia (ALL), early response to treatment is an important prognostic factor and drug resistance is a major cause of poor outcome. One of the most investigated resistance mechanisms is P-glycoprotein (P-gp)-mediated multiple drug resistance (MDR). We analyzed P-gp using flow cytometry with monoclonal antibody JSB1 in a series of 118 children with ALL, 103 at diagnosis and 15 at relapse. Increased P-gp expression was found in 55 (53%) patients at diagnosis and in 11 (73%) at relapse. We also analyzed the bone marrow aspirate slides for early response to treatment in a central review. No correlation was found between P-gp and early response. Patients with T-ALL had higher P-gp levels than the others, 5.3% versus 1.0% (P = .002). We conclude that P-gp-mediated multiple drug resistance is not a factor in a slow response to ALL induction therapy.

Early response to therapy and outcome in childhood acute lymphoblastic leukemia: a review

BACKGROUND

Early response to therapy is defined as the initial response prior to Day 28 of treatment, the conventional time of marrow evaluation. The number of reports linking early response to therapy with the ultimate outcome of childhood acute lymphoblastic leukemia is substantial and growing. When this study began, these experiences had yet to be comprehensively reviewed.

METHODS

A comprehensive search of the published literature yielded contributory reports of 14 trials conducted in the United States and Europe. In addition, unpublished data from one Children's Cancer Group trial were made available. Outcome measures were standardized by conversion to ratios of the incidence of adverse events among poorer and better responders.

RESULTS

Early response to therapy was an independent prognostic factor in each of the 15 trials, which together included more than 10,000 patients. The incidence of slower early response ranged from 2-33%, with various measures and criteria used in different trials. Patients with a slower early response were 1.5-6.1 times (median, 2.7) more likely to have an adverse event than patients with a more rapid early response, however defined. Early response maintained prognostic significance after the exclusion of induction failure and within risk strata defined by age, white blood cell count, and/or immunophenotype. Its significance was also maintained in multivariate analyses where performed.

CONCLUSIONS

Early response to therapy, whether determined by evaluation of bone marrow or peripheral blood, is a consistent, independent prognostic factor in childhood acute lymphoblastic leukemia. Slower early response may serve as a useful surrogate for outcome, a more complex end point, in investigations of the cellular and molecular determinants of resistance to therapy. It may also allow early identification of a patient subpopulation for whom current therapy is less effective and alternative strategies may be justified.

Importance of the day 7 bone marrow biopsy as a prognostic measure of the outcome in children with acute lymphoblastic leukemia

The presence of > or = 25% blasts in a marrow aspirate obtained on day 7 of induction followed by a remission at day 28 has been associated with a poor prognosis in children with acute lymphoblastic leukemia (ALL). We evaluated whether a day 7 marrow biopsy may be used to more accurately assess therapeutic reduction of leukemia tumor burden. Studied were 76 children with ALL enrolled on CCG protocols at B.C's Children's Hospital who received both a day 7 aspirate and biopsy and were in remission by day 28. Evaluation for the correlation of the percentage aspirate blasts on day 7 with the biopsy demonstrated a moderate correlation with the percentage biopsy blasts (R = 61), but not correlation with the biopsy cellularity. We saw a similar prediction of outcome by the percentage blasts on day 7 marrow aspirate in the study as reported previously although it was not significant. Outcome analysis was done using leukemia burden as measured by the day 7 absolute blast index-aspirate (ABI-aspirate) calculated as the product of the biopsy cellularity with the percentage blasts on the aspirate. The ABI-aspirate significantly predicted patient outcome with 83% survival in those with an ABI-aspirate of < .06 compared to 51% in those > or = .06 (P = .01) and was highly significant when analyzed as a continuous predictor (P = .004). This is the first study to demonstrate that information gained from the day 7 marrow biopsy can improve prediction of outcome in children with ALL. Based on this preliminary study, we recommend that large population ALL therapy trials evaluate the role of the day 7 marrow biopsy for outcome prediction in children with ALL.

Homozygous Deletion of the p16/MTS1 Gene in Pediatric Acute Lymphoblastic Leukemia Is Associated With Unfavorable Clinical Outcome

The p16 gene (MTS1, CDKN2, p16INK4A, CDKI) encoding an inhibitor of cyclin-dependent kinase 4 (cdk4) has been found to be deleted in various types of tumors, including leukemia, and is thought to code for a tumor suppressor gene. Our preliminary findings on eight pediatric patients with acute lymphoblastic leukemia (ALL) suggested that the survival of patients carrying a homozygous p16 gene deletion was significantly inferior to that of those without a deletion. The present study on 48 patients tested the hypothesis that the clinical outcome for pediatric ALL patients is correlated with the presence or absence of the p16 gene. Overall, nine of 48 children (18.3%) carried a homozygous p16 deletion. Such deletions were significantly more common (P = .003) among T-ALL patients (five of eight, 62.5%) than among precursor-B-ALL patients (four of 40, 10.0%). Of nine patients exhibiting p16 deletions, eight (88.9%) were classified as high-risk patients by the recognized prognostic factors of age, white blood cell count, and T-cell phenotype. The 4-year event-free survival in the study population as a whole was 72.7%. Without adjustment for other risk factors (univariate model), the presence of a homozygous p16 deletion was associated with a markedly increased probability of both relapse (P = .0003) and death (P = .002). These findings raise the question of whether the p16 deletion itself confers an increased risk of relapse after adjusting for the known risk factors. In this analysis, the estimated risk multiplier factor for relapse in patients carrying the p16 deletion was 14.0 (P = .0004) and for the risk of death 15.6 (P = .0008). We therefore conclude that the presence of a homozygous p16 deletion may well be an important risk factor for both relapse and death in childhood ALL, and that its prognostic effect is not a consequence of confounding by other factors already known to influence outcome in this disease.

Cellular Expression of Antiapoptotic BCL-2 Oncoprotein in Newly Diagnosed Childhood Acute Lymphoblastic Leukemia: A Children's Cancer Group Study

We found a marked variation in BCL-2 oncoprotein expression levels of primary leukemic cells from 338 children with newly diagnosed acute lymphoblastic leukemia (ALL). None of the high-risk features predictive of poor treatment outcome in childhood ALL, such as older age, high white blood cell (WBC) count, organomegaly, T-lineage immunophenotype, ability of leukemic cells to cause overt leukemia in severe combined immunodeficient (SCID) mice, presence of MLL-AF4, and BCR-ABL fusion transcripts were associated with high levels of BCL-2 expression. Overall, high BCL-2 levels were not associated with slow early response, failure to achieve complete remission, or poor event-free survival. High BCL-2 levels in primary leukemic cells predicted slow early response only in T-lineage ALL patients, which comprised approximately 15% of the total patient population. Even for this small subset of patients, the level of BCL-2 expression did not have a significant impact on the short-term event-free survival.

Cellular Expression of Antiapoptotic BCL-2 Oncoprotein in Newly Diagnosed Childhood Acute Lymphoblastic Leukemia: A Children's Cancer Group Study

We found a marked variation in BCL-2 oncoprotein expression levels of primary leukemic cells from 338 children with newly diagnosed acute lymphoblastic leukemia (ALL). None of the high-risk features predictive of poor treatment outcome in childhood ALL, such as older age, high white blood cell (WBC) count, organomegaly, T-lineage immunophenotype, ability of leukemic cells to cause overt leukemia in severe combined immunodeficient (SCID) mice, presence of MLL-AF4, and BCR-ABL fusion transcripts were associated with high levels of BCL-2 expression. Overall, high BCL-2 levels were not associated with slow early response, failure to achieve complete remission, or poor event-free survival. High BCL-2 levels in primary leukemic cells predicted slow early response only in T-lineage ALL patients, which comprised approximately 15% of the total patient population. Even for this small subset of patients, the level of BCL-2 expression did not have a significant impact on the short-term event-free survival.

Randomized comparison of rotational chemotherapy in high-risk acute lymphoblastic leukaemia of childhood--follow up after 9 years. Coall Study Group

A frequent change of drug combinations may circumvent drug resistance in the treatment of patients with acute lymphoblastic leukaemia (ALL). In study COALL 85/89 201 children with high-risk ALL were randomized to receive over a period of 8 months rotational chemotherapy with six drug combinations given either in slow rotation (SR) (each combination given twice in succession) or in rapid rotation (RR) (each combination given once with a repetition of the drug combinations). Treatment of central nervous system leukaemia consisted of cranial irradiation and intrathecal methotrexate. Both SR and RR treatment groups were then given continuation chemotherapy of oral 6-mercaptopurine and methotrexate until 2 years after the date of diagnosis. The 9-year event-free survival (EFS) rate for the whole group is 69% +/- 3%, and the survival rate 75% +/- 3% at a median follow up of 5.8 years. Failure to achieve remission at day 28 was the most important prognostic factor (EFS 12% +/- 7% vs. 75% +/- 3% in the remission group). In the RR group, 11/100 patients were not in remission at day 28 opposed to 7/101 patients in the SR group. Children aged < 1 year (6/6 relapses) or aged > or = 10 years had a worse prognosis (EFS 64% +/- 5% vs. 77% +/- 4% in patients 1-10 years old). After 5 years EFS was inferior in the RR group attributable to a significantly higher relapse rate in children with a WBC > or = 100/nl. The EFS at 9 years for all patients, however, is similar in both groups (SR 72% +/- 5% vs. RR 67 +/- 5%).

CONCLUSION

The COALL 85/89 treatment protocol with early intensive therapy and rotation of different drug combinations offers longterm disease-free survival for children with high-risk ALL. a continuous 4-week exposure to one drug combination may be necessary to achieve optimal results, especially in children with a high leukaemic cell burden.

Improved therapy for children with acute lymphoblastic leukemia

We have examined the factors influencing clinical prognosis in Japanese children with B-precursor acute lymphoblastic leukemia (ALL), who have been treated in consecutive chemotherapeutic trials from 1976 to 1995. During this time the results of treatment have steadily improved in children with average presenting features (age 1-10 years old and leukocyte counts > 50,000/microL). The 4-year event-free survival (EFS) estimates now exceed 85% in our current trials. Furthermore, high-dose methotrexate and intrathecal therapy could be substituted for cranial irradiation without an increase of central nervous system relapse rate. However, children with unfavorable presenting features (leukocyte counts > or = 50,000/microL; high-risk group) have a worse prognosis, although there is some improvement of outcome. The patients in the high-risk group have obtained the 4-year EFS rate of better than 60%. Further investigations of prognostic factors in ALL focused on the biological features may permit identification of groups of children at risk of very poor outcome. In the patient cohorts consistently resistant to chemotherapy, the hazards of more intensive treatment such as bone marrow transplantation may be outweighed by the possible benefits.