Comparison of bone marrow transplant and chemotherapy for relapsed childhood acute lymphoblastic leukaemia: the MRC UKALL X experience. Medical Research Council Working Party on Childhood Leukaemia

TBI, etoposide, and cyclophosphamide conditioning for intermediate-risk relapsed childhood acute lymphoblastic leukemia

BACKGROUND

In children with intermediate-risk relapsed acute lymphoblastic leukemia (ALL), allogeneic hematopoietic stem cell transplantation (allo-HSCT) has markedly improved the outcome of patients with an unsatisfactory minimal residual disease (MRD) response. Total body irradiation (TBI), etoposide (ETP), and cyclophosphamide (CY) have been shown to be equivalent to or better than TBI + ETP for conditioning, so we hypothesized that even greater survival could be achieved due to recent advances in HSCT and supportive care.

PROCEDURE

We prospectively analyzed the efficacy and safety of allo-HSCT with a unified conditioning regimen of TBI + ETP + CY in children with intermediate-risk relapsed ALL, based on MRD in the bone marrow after induction, from the Japanese Pediatric Leukemia/Lymphoma Study Group (JPLSG) ALL-R08-II nationwide cohort (UMIN000002025).

RESULTS

Twenty patients with post-induction MRD ≥ 10-3 and two not evaluated for MRD underwent allo-HSCT. Engraftment was confirmed in all patients, and no transplantation-related mortality was observed. The 3-year event-free survival and overall survival rates after transplantation were 86.4% ± 7.3% and 95.5% ± 4.4%, respectively.

CONCLUSION

Allo-HSCT based on post-induction MRD with TBI + ETP + CY conditioning was feasible in Japanese children with intermediate-risk relapsed ALL.

Novel Treatments for Pediatric Relapsed or Refractory Acute B-Cell Lineage Lymphoblastic Leukemia: Precision Medicine Era

With the markedly increased cure rate for children with newly diagnosed pediatric B-cell acute lymphoblastic leukemia (B-ALL), relapse and refractory B-ALL (R/R B-ALL) remain the primary cause of death worldwide due to the limitations of multidrug chemotherapy. As we now have a more profound understanding of R/R ALL, including the mechanism of recurrence and drug resistance, prognostic indicators, genotypic changes and so on, we can use newly emerging technologies to identify operational molecular targets and find sensitive drugs for individualized treatment. In addition, more promising and innovative immunotherapies and molecular targeted drugs that are expected to kill leukemic cells more effectively while maintaining low toxicity to achieve minimal residual disease (MRD) negativity and better bridge hematopoietic stem cell transplantation (HSCT) have also been widely developed. To date, the prognosis of pediatric patients with R/R B-ALL has been enhanced markedly thanks to the development of novel drugs. This article reviews the new advancements of several promising strategies for pediatric R/R B-ALL.

Haploidentical hematopoietic stem cell transplantation for paediatric high-risk T-cell acute lymphoblastic leukaemia

Paediatric HR T-cell ALL demonstrates dismal prognosis with chemotherapy, and poor outcomes could be improved with allo-SCT. HID-SCT is an almost immediately available choice; however, few studies have focused on the outcomes of HID-SCT for paediatric HR T-ALL. Forty-eight consecutive HR T-ALL children who underwent HID-SCT were included. Survival outcomes and factors predictive of outcomes were retrospectively analysed. Of the 48 patients, 35 were in CR1, 10 in CR2, and three in relapse. The cumulative incidence of grade 3/4 aGVHD was 10.4% and that of extensive cGVHD was 28.4%. The CIR at three yr was 30.8% and that of NRM at three yr was 14.7%. At a median follow-up of 20.0 (range 2.5-124.2) months, the three-yr LFS was 54.4%. Children who received transplants during CR1 had a better LFS (65.7% vs. 26.0%, p = 0.008) and a lower relapse rate (19.8% vs. 56.7%, p = 0.014) compared to those during non-CR1. HID-SCT is feasible for HR T-ALL children, and survival outcomes are better when performed in CR1 compared to non-CR1. Prospective clinical trials would be needed to confirm that.

Off-therapy procedures are not beneficial in pediatric B-cell acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is the most common childhood cancer. Although curable, approximately 20% of patients relapse. In an effort to detect relapse earlier, our institution performed surveillance bone marrow (BM) and cerebrospinal fluid (CSF) evaluations every 3 months from the end of therapy to 1 year off. This study retrospectively reviewed all patients with B-cell ALL (B-ALL) from September 2005 to September 2010 to determine the benefit and cost of these procedures. Forty-one patients completed therapy and had 190 BMs and 190 lumbar punctures (LPs) performed. Four of 41 patients (9.8%) experienced a relapse. Relapse was detected in only 1 patient by routine BM evaluation (0.5%). Zero LPs were positive. The professional fees for the procedures were $8,738/patient. Therefore, off-therapy BM and CSF evaluations are not effective at detecting relapse and are expensive. Our institution has abandoned off-therapy surveillance for ALL.

Treatment of relapsed precursor-B acute lymphoblastic leukemia with intensive chemotherapy: POG (Pediatric Oncology Group) study 9411 (SIMAL 9)

Pediatric patients who experience a bone marrow relapse of precursor-B acute lymphoblastic leukemia are cured <50% of the time. This study was designed to determine if intensification of therapies with known activity in this disease would improve the cure rates for patients with relapsed acute lymphoblastic leukemia. Patients were treated with intensive asparaginase during induction followed by repeated cycles of ifosfamide/etoposide and cytarabine/idarubicin. Patients with well-matched related donors were encouraged to undergo hematopoietic stem cell transplant as consolidation. The results of this study demonstrate no significant difference in disease-free survival in patients who received chemotherapy alone (45%) or chemotherapy followed by allogeneic stem cell transplant (50%). Furthermore, results from this study show no significant difference in event-free survival (39.9%±6.2%) or overall survival (41.6%±6.1%) at 8 years when compared with previous studies using less intensive regimens. Our results suggest that alternative therapies are needed to improve cure rates for pediatric patients with relapsed leukemia.

How to treat relapsed acute lymphoblastic leukemia: transplant vs. conventional chemotherapy

Management of relapsed acute lymphoblastic leukemia (ALL) is challenging and far from satisfactory. The treatment approaches are often varied and controversial. The duration of first remission, site of relapse, immunophenotypic and molecular characteristics of relapsed disease and response to therapy influence treatment outcome. There are three main therapeutic options i.e., chemotherapy alone, induction chemotherapy followed by HLA matched allogeneic transplant and palliation. These may be chosen based on the above mentioned factors. The response to therapy may be evaluated morphologically or by minimal residual disease (MRD). Persistence of MRD, as assessed by molecular techniques or through flowcytometry, clearly influences prognosis in children with relapsed ALL. It not only helps in identifying the subset of patients likely to benefit from allogeneic bone marrow transplant (ABMT) but also in determining the timing of transplant. Patients with non-T phenotype, with late relapsing disease and good response to re-induction therapy have been shown to do equally well with chemotherapy alone. On the other hand patients with early relapse and poor initial response are selected for ABMT. With the improvement in supportive care, better selection of HLA match donors and better immunosuppressive therapies, transplant related mortality has decreased considerably. Despite all of these overall salvage rates are still poor and novel agents are being tested in various trials to establish their role in relapsed ALL therapy.

Prognosis and outcome of relapsed acute lymphoblastic leukemia: a Hong Kong Pediatric Hematology and Oncology Study Group report

BACKGROUND

In 2000, the Hong Kong Pediatric Hematology Oncology Study Group started a new relapsed acute lymphoblastic leukemia (ALL) treatment protocol based on modified ALL-REZ BFM 96 protocol aiming at improving the treatment outcome in Chinese children.

PROCEDURE

All patients in Hong Kong with first relapse of childhood ALL were included. Patients were stratified into four risk groups (S1, S2, S3, and S4) and the treatment consisted of intensive chemotherapy followed by allogeneic hematopoietic stem cell transplantation, if indicated.

RESULTS

Fifty-six patients were recruited and median age at diagnosis of ALL was 4.6 (range, 0.3-17) years. The median time from initial diagnosis to relapse was 2.5 (range, 0.3-9.1) years and follow-up time was 2.7 (range, 0-9.9) years. Forty-nine patients (87.5%) achieved second complete remission (CR2). CR2 rates for S1, S2, S3, and S4 groups were 100%, 93%, 90%, and 67%, respectively. Five-year overall survival (OS) was 50.5 ± 6.9% and event-free survival (EFS) was 41.5 ± 7.1%. There was no significant difference in survival among S1, S2, and S3 groups but S4 patients performed significantly worse with 5-year OS and EFS of 8% and 0%, respectively.

CONCLUSION

Children with relapsed ALL of S1-S3 risk groups could be successfully treated with intensified treatment protocol. The S4 high risk group needs more innovative approach to improve treatment outcome.

Role of cytotoxic therapy with hematopoietic stem cell transplantation in the treatment of pediatric acute lymphoblastic leukemia: update of the 2005 evidence-based review

Clinical research published since the first evidence-based review on the role of hematopoietic stem cell transplantation (SCT) in the treatment of pediatric acute lymphoblastic leukemia (ALL) is presented and critically evaluated in this update. Treatment recommendations are provided by an expert panel. Allogeneic SCT is recommended for children who: are in second complete remission (CR2) after experiencing an early marrow relapse for precursor-B ALL; experienced primary induction failure, but subsequently achieved a CR1; have T-lineage ALL in CR2; or have ALL in third or greater remission. Although the 2005 pediatric ALL evidence-based review (EBR) recommended allogeneic SCT for children with Philadelphia chromosome positive (Ph+) ALL in CR1, preliminary tyrosine kinase inhibitor (TKI) data demonstrate that early outcomes are comparable for allogeneic SCT and chemotherapy + imatinib. Based on the evidence, autologous SCT is not recommended for ALL in CR1. Allogeneic SCT is not recommended for: T-lineage ALL in CR1; mixed-lineage leukemia (MLL)+ ALL when it is the sole adverse risk factor; isolated central nervous system (CNS) relapse in precursor-B ALL. Based on expert opinion, allogeneic SCT may be considered for hypodiploid ALL and persistent minimal residual disease [corrected] (MRD) positivity in ALL in CR1 or greater, although these are areas that need further study. Treatment recommendations pertaining to various transplantation techniques are also provided, as are areas of needed future research.

Outcome after first relapse in children with acute lymphoblastic leukemia: a report based on the Dutch Childhood Oncology Group (DCOG) relapse all 98 protocol

BACKGROUND

We report on the treatment of children and adolescents with acute lymphoblastic leukemia (ALL) in first relapse. The protocol focused on: (1) Intensive chemotherapy preceding allogeneic stem cell transplantation (SCT) in early bone marrow relapse; (2) Rotational chemotherapy in late relapse, without donor; (3) Postponement of cerebro-spinal irradiation in late isolated CNS relapse; and (4) Treatment in very late bone marrow relapse with chemotherapy only.

METHODS

From January 1999 until July 2006 all 158 Dutch pediatric patients with ALL in first relapse were recorded. Ninety-nine patients were eligible; 54 patients with early and 45 with late relapse. Eighteen patients had an isolated extra-medullary relapse; 69 patients had bone marrow involvement only.

RESULTS

Five-years EFS rates for early and late relapses were 12% and 35%, respectively. For early relapses 5 years EFSs were 25% for patients transplanted; 0% for non-transplanted patients. For late relapses 5 years EFS was 64% for patients treated with chemotherapy only, and 16% for transplanted patients. For very late relapses EFS was 58%.

CONCLUSIONS

Our data suggest the superiority of SCT for early relapse patients. For late relapses a better outcome is achieved with chemotherapy only using the rotational chemotherapy scheme. The most important factor for survival was interval between first CR and occurrence of the first relapse.

Relapse of acute lymphoblastic leukemia in children in the context of microarray analyses

Over the last four decades the treatment of patients with newly diagnosed childhood acute lymphoblastic leukemia (ALL) has improved remarkably. However, still about 20% of children with ALL relapse despite risk-adapted polychemotherapy. The prognosis of relapsed ALL is relatively poor, even with modern aggressive chemotherapy. Identification of the biological and genetic mechanisms contributing to recurrence in patients with ALL is critical for the development of effective therapeutic strategies to treat refractory leukemic patients. Allogeneic hematopoietic stem-cell transplantation is the treatment of choice for many children with relapsed ALL. The gene expression profile obtained by microarray technology could provide important determinants of the drug response and clinical outcome in childhood ALL. Incorporation of the data on expression levels of newly identified genes into existing strategies of risk stratification might improve clinical management. Current microarray data show correlation of in vitro drug resistance with significant patterns of gene expression and explain clinical differences between early and late relapse. Genes involved in cell proliferation, self-renewal and differentiation, protein biosynthesis, carbohydrate metabolism, and DNA replication and repair are usually among those highly expressed in relapsed lymphoblasts. Current status and future perspectives of microarray data on gene expression and drug resistance profile in relapsed pediatric ALL are discussed in this review.

Isolated extramedullary relapse in childhood acute lymphocytic leukemia

Although the vast majority of children with acute lymphocytic leukemia attain remission with modern therapies, an unacceptably high number will suffer a disease relapse. Both the duration of remission and the site of relapse are important prognostic factors. This review focuses on leukemic relapse isolated to sites outside the bone marrow (extramedullary sites). Data from cooperative study groups as well as large single institutions are reviewed with respect to the incidence of isolated extramedullary relapse as well as the outcome following relapse. The unique anatomic and physiologic properties of the testes and the central nervous system-the two most common sites of isolated extramedullary relapse-are discussed. Finally, the evolution of leukemia therapy is reviewed, bringing into focus the goals and challenges of future therapeutic endeavors.

Improved outcome in childhood ALL with intensive consolidation and hematopoietic stem cell transplant

Background

Despite advances in chemotherapy, the prognosis of relapsed acute lymphoblastic leukemia (ALL) remains poor. Few studies on relapsed ALL have reported the importance of intensive consolidation followed with or without allogeneic hematopoietic stem cell transplantation (HSCT).

Methods

We evaluated the post-relapse outcomes in 47 Korean children with a first marrow relapse, and analyzed the prognostic factors.

Results

A second complete remission (CR) was achieved in 40 patients (85.1%), and at the time of this study, second CR was maintained in 12 of these patients. The estimated 3-yr event-free survival (EFS) rate after the first marrow relapse was 29.8±6.7%, and the overall survival (OS) rate was 45.3±7.5%. We found that second remission, consolidation of pediatric oncology group chemotherapy regimen (POG 9411), and HSCT significantly affected the outcome of the disease after relapse (P<0.001; P=0.004; P=0.05).

Conclusion

The results of our study revealed that an intensified POG 9411 consolidation chemotherapy regimen followed by HSCT can improve the outcome of patients with relapsed ALL.

Long-term outcome in children with relapsed acute lymphoblastic leukemia after time-point and site-of-relapse stratification and intensified short-course multidrug chemotherapy: results of trial ALL-REZ BFM 90

PURPOSE

The multicenter trial ALL-REZ BFM (ie, Acute Lymphoblastic Leukemia Relapse Berlin-Frankfurt-Münster) 90 was designed to improve prognosis for children with relapsed acute lymphoblastic leukemia (ALL) by time-to-relapse- and site-of-relapse-adapted stratification and by introduction of novel chemotherapy elements and to evaluate new prognostic parameters in a large, population-based cohort.

PATIENTS AND METHODS

Five hundred twenty-five patients stratified into risk groups A (early bone marrow [BM] relapses), B (late BM relapses), and C (isolated extramedullary relapses) received alternating short-course intensive polychemotherapy (in blocks R1, R2, or R3) and cranial/craniospinal irradiation followed by maintenance therapy. Block R3 (high-dose cytarabine and etoposide) was introduced to improve the outcome compared with historical controls. Patients with early BM or T-ALL relapse (poor prognosis group [PPG]) were eligible for experimental regimens. One hundred seventeen patients received stem-cell transplantation (SCT).

RESULTS

The probabilities (and standard deviations) of event-free survival (pEFS) and overall survival (pOS) at 10 years were 0.30 +/- .02 and 0.36 +/- .02, respectively. Significant differences existed between strategic groups (pEFS(A) = .17 +/- .03; pEFS(B) = .43 +/- .04; pEFS(C) = .54 +/- .06; pEFS(PPG) = .15 +/- .03; log-rank P < .001). Patients of high-risk groups A plus PPG did better with SCT than with chemotherapy (pEFS = .33 +/- .05 v 0.20 +/- .05; P = .005). The pEFS was similar to trials ALL-REZ BFM 85/87 (.36 +/- .03. v 0.37 +/- .03; P = .419; PPG excluded). Time point, site of relapse, immunophenotype, and SCT were significant predictors of pEFS in multivariate analyses.

CONCLUSION

More than one third of patients in this large, population-based trial were cured. Neither R3 nor adaptation of chemotherapy intensity was capable of improving pEFS or of overcoming prognostic factors. In high-risk patients, remission induction regimens must be improved, and allogeneic SCT should be recommended in patients achieving second complete remission.

Stem cell source and outcome after hematopoietic stem cell transplantation (HSCT) in children and adolescents with acute leukemia

Allogeneic hematopoietic stem cell transplantation from siblings, unrelated donors or HLA mismatched family members has become an important procedure to offer a chance of cure to children and adolescents with acute leukemia at high risk of relapse and those with certain genetic diseases. Bone marrow (BM) was the only stem cell source for many years. During the past 15 years, peripheral blood stem cells from granulocyte colony-stimulating factor (G-CSF) mobilized healthy donors, or umbilical cord blood from related or unrelated donors, have become available. Each stem cell source has different risks/benefits for patients and donors, the choice depending not only on availability, but also on HLA compatibility and urgency of the HSCT. This review will analyze the advantages and limitations of each of these options, and the main criteria which can be applied when choosing the appropriate stem cell source for pediatric transplant recipients with acute leukemia.

Hematopoietic stem cell transplantation for leukemia

Leukemia represents the most common pediatric malignancy, accounting for approximately 30% of all cancers in children less than 20 years of age. Most children diagnosed with leukemia are cured without hematopoietic stem cell transplantation (HSCT), but for some high-risk subgroups, allogeneic HSCT plays an important role in their therapeutic approach. The characteristics of these high-risk subgroups and the role of HSCT in childhood leukemias are discussed.

Temporal changes in the incidence and pattern of central nervous system relapses in children with acute lymphoblastic leukaemia treated on four consecutive Medical Research Council trials, 1985-2001

Despite the success of contemporary treatment protocols in childhood acute lymphoblastic leukaemia (ALL), relapse within the central nervous system (CNS) remains a challenge. To better understand this phenomenon, we have analysed the changes in incidence and pattern of CNS relapses in 5564 children enrolled on four successive MRC-ALL trials between 1985 and 2001. Changes in the incidence and pattern of CNS relapses were examined and the relationship with patient characteristics assessed. Factors affecting post-relapse outcome were determined. Overall, relapses declined by 49%. Decreases occurred primarily in non-CNS and combined relapses with a progressive shift towards later (≥30 months from diagnosis) relapses (p<0·0001). Although isolated CNS relapses declined, the proportional incidence and timing of relapse remained unchanged. Age and presenting white cell count were risk factors for CNS relapse. On multivariate analysis, the time to relapse and the trial period influenced post-relapse outcomes. Relapse trends differed within biological subtypes. In ETV6-RUNX1 ALL, relapse patterns mirrored overall trends while in High Hyperdiploidy ALL, these appear to have plateaued over the latter two trial periods. Intensive systemic and intrathecal chemotherapy have decreased the overall CNS relapse rates and changed the patterns of recurrence. The heterogeneity of therapeutic response in the biological subtypes suggests room for further optimisation using currently available chemotherapy.

Pattern of relapsed disease in childhood all: experience from a single tertiary care center in North India

The study was designed to determine the pattern of relapsed disease and identify problem areas in management. Relapse occurred in 111 (23.9%) of the boys and 16 (13.0%) of the girls. The majority relapsed while on chemotherapy. Isolated relapse in the marrow and in the CNS was seen in 51 (40.8%) and 24 (18.9%) patients, respectively. Isolated testicular relapse was seen in 17 (15.3%) of the 111 boys who suffered a relapse. Age and TLC at initial presentation and gender in relapsers and nonrelapsers were compared. Multivariate regression analysis showed that gender (p = .03) and TLC (p = .001) were significant predictors of relapse. Relapse of disease while on chemotherapy and high incidence of CNS and testicular relapse indicate the need for reappraisal of treatment protocols.

Myeloablative hematopoietic cell transplantation for acute lymphoblastic leukemia: analysis of graft sources and long-term outcome

PURPOSE

Analysis of hematopoietic cell transplantation (HCT) for high-risk or recurrent acute lymphoblastic leukemia (ALL) using different donor sources is confounded by variable conditioning and supportive care.

PATIENTS AND METHODS

We studied 623 consecutive ALL myeloablative HCT (1980 to 2005). Donors were autologous (n = 209), related (RD; n = 245), unrelated (URD; n = 100), and umbilical cord blood (UCB; n = 69).

RESULTS

After median of 8.3 years of follow-up, 5-year overall survival (OS), leukemia-free survival (LFS), and relapse were 29% (95% CI, 26% to 32%), 26% (95% CI, 23% to 29%), and 43% (95% CI, 39% to 47%), respectively. Treatment-related mortality (TRM) at 2 years was 28% (95% CI, 25% to 31%). Mismatched URD sources yielded higher TRM (relative risk [RR], 2.2; P < .01) and lower OS (RR, 1.5; P = .05) than RD or UCB HCT. Autografting yielded significantly more relapse (68%; 95% CI, 59% to 77%; P < .01) and poorer LFS (14%; 95% CI, 10% to 18%; P = .01). HCT in first complete remission (CR1) yielded significantly better outcomes than later HCT. In a 1990 to 2005 allogeneic CR1/second complete response cohort, 5-year OS, LFS, and relapse rates were 41% (95% CI, 35% to 47%), 38% (95% CI, 32% to 44%), and 25% (95% CI, 19% to 31%), respectively; 2-year TRM was 34% (95% CI, 28% to 40%). With RD, well-matched URD and UCB sources, 5-year LFS was 40% (95% CI, 31% to 49%), 42% (95% CI, 14% to 70%), and 49% (95% CI, 34% to 64%), respectively, while relapse was 31% (95% CI, 22% to 40%), 17% (95% CI, 0% to 37%), and 27% (95% CI, 13% to 41%). Acute graft-versus-host disease was associated with fewer relapses. Since 1995, we noted progressive improvements in OS, LFS, and TRM.

CONCLUSION

Allogeneic, but not autologous, HCT for ALL results in durable LFS. Importantly, HCT using UCB led to similar outcomes as either RD or well-matched URD. HCT in early remission can best exploit the potent antileukemic efficacy of allografting from UCB, RD, or URD sources.

Long-term outcome of initially homogenously treated and relapsed childhood acute lymphoblastic leukaemia in Austria--a population-based report of the Austrian Berlin-Frankfurt-Münster (BFM) Study Group

Relapsed acute lymphoblastic leukaemia (ALL) is the most common cause for a fatal outcome in paediatric oncology. Although initial ALL cure rates have improved up to 80%, the prognosis of recurrent ALL remains dismal with event-free-survival (EFS) rates about 35%. In order to analyse a population-based cohort with uniform treatment of initial disease, we examined the outcome of children suffering from relapsed ALL in Austria for the past 20 years and the validity of the currently used prognostic factors (e.g. time to and site of relapse, immunophenotype). Furthermore, we compared survival rates after chemotherapy alone with those after allogeneic stem cell transplantation (SCT). All 896 patients who suffered from ALL in Austria between 1981 and 1999 were registered in a prospectively designed database and treated according to trials ALL-Berlin-Frankfurt-Münster (BFM)-Austria (A) 81, ALL-A 84 and ALL-BFM-A 86, 90 and 95. Of these, 203 (23%) suffered from recurrent disease. One-hundred-and-seventy-two patients (85%) achieved second complete remission. The probability of 10-year EFS for the total group was 34 +/- 3%. Clinical prognostic markers that independently influenced survival were time to relapse, site of relapse and the immunophenotype. Additionally, a Cox regression model demonstrated that allogeneic SCT after first relapse was associated with a superior EFS compared with chemo/radiotherapy only (hazard ratio = 0.254; P = 0.0017).

Factors influencing survival after relapse from acute lymphoblastic leukemia: a Children's Oncology Group study

Despite great progress in curing childhood acute lymphoblastic leukemia (ALL), survival after relapse remains poor. We analyzed survival after relapse among 9585 pediatric patients enrolled on Children's Oncology Group clinical trials between 1988 and 2002. A total of 1961 patients (20.5%) experienced relapse at any site. The primary end point was survival. Patients were subcategorized by the site of relapse and timing of relapse from initial diagnosis. Time to relapse remains the strongest predictor of survival. Patients experiencing early relapse less than 18 months from initial diagnosis had a particularly poor outcome with a 5-year survival estimate of 21.0+/-1.8%. Standard risk patients who relapsed had improved survival compared with their higher risk counterparts; differences in survival for the two risk groups was most pronounced for patients relapsing after 18 months. Adjusting for both time and relapse site, multivariate analysis showed that age (10+ years) and the presence of central nervous system disease at diagnosis, male gender, and T-cell disease were significant predictors of inferior post-relapse survival. It can be noted that there was no difference in survival rates for relapsed patients in earlier vs later era trials. New therapeutic strategies are urgently needed for children with relapsed ALL and efforts should focus on discovering the biological pathways that mediate drug resistance.

Bone-marrow relapse in paediatric acute lymphoblastic leukaemia

Marrow relapse is the major obstacle to cure for 10-15% of young patients with acute lymphoblastic leukaemia (ALL). Recent investigations into the biology of minimal residual disease indicate that many early relapses derive from residual cells present at first diagnosis, but some late relapses might represent new mutations in leukaemic cells not eliminated by conventional therapy. Treatment of marrow relapse involves higher doses and more intensive schedules of the drugs used for initial therapy with or without haemopoietic stem cell transplantation. In most reports, transplantation is better than continuation chemotherapy in early marrow relapse, but its role in later relapse is less clear. Current therapy cures 10% of patients with early marrow relapses and 50% of those with late relapses, but outcomes have changed little in the past two decades. Understanding the molecular biology of ALL underlies development of improved risk stratification and new therapies. Although better drugs are needed, introduction of new agents into clinical trials in paediatric disease has been difficult. Innovative trial designs and use of valid surrogate endpoints may expedite this process.

Outcome After Relapse Among Children With Standard-Risk Acute Lymphoblastic Leukemia: Children's Oncology Group Study CCG-1952

Purpose

The event-free survival (EFS) of children with standard-risk acute lymphoblastic leukemia (SR-ALL) is now more than 80%. However, prognosis after relapse continues to be poor. We examined postrelapse outcomes of children initially treated on the Children's Cancer Group CCG-1952 study.

Patients and Methods

We evaluated outcomes after bone marrow (BM) relapse and isolated extramedullary (EM) relapse for 347 patients with SR-ALL (WBC < 50,000/μL; age, 1 to 9 years). The prognostic significance of several factors for EFS after relapse (EFS2) was assessed by Cox regression analysis. Stem-cell transplant (SCT) was compared with chemotherapy as salvage treatment.

Results

The mean ± SE times to isolated central nervous system relapse, BM relapse, and isolated testicular relapse were 23 ± 1 months (range, 1 to 88 months), 36 ± 1 months (range, 2 to 79 months), and 40 ± 2 months (range, 16 to 64 months), respectively. The estimated percent ± SE 3-year EFS2 and overall survival rates after BM relapse were 37% ± 4% and 46% ± 4%, respectively, and rates after isolated EM relapse were 57% ± 5% and 71% ± 5%, respectively. By multivariate analysis, we found the duration of first remission to be the most significant predictor of EFS2 for either BM relapse or isolated EM relapse. Outcome was equivalent with SCT or chemotherapy after early or late relapse of SR-ALL at any site.

Conclusion

Duration of first remission remains the most significant predictor of outcome after either BM or isolated EM relapse of SR-ALL. Prognosis after early BM relapse remains poor and is not improved with SCT in this cohort.

High-dose compared with intermediate-dose methotrexate in children with a first relapse of acute lymphoblastic leukemia

High-dose methotrexate (MTX) has been extensively used for treatment of acute lymphoblastic leukemia (ALL). To determine the optimal dose of MTX in childhood relapsed ALL, the ALL Relapse Berlin-Frankfurt-Münster (ALL-REZ BFM) Study Group performed this prospective randomized study. A total of 269 children with a first early/late isolated (n = 156) or combined (n = 68) bone marrow or any isolated extramedullary relapse (n = 45) of precursor B-cell (PBC) ALL (excluding very early marrow relapse within 18 months after initial diagnosis) were registered at the ALL-REZ BFM90 trial and randomized to receive methotrexate infusions at either 1 g/m(2) over 36 hours (intermediate dose, ID) or 5 g/m(2) over 24 hours (high dose, HD) during 6 (or 4) intensive polychemotherapy courses. Intensive induction/consolidation therapy was followed by cranial irradiation, and by conventional-dose maintenance therapy. Fifty-five children received stem-cell transplants. At a median follow-up of 14.1 years, the 10-year event-free survival probability was .36 (+/- .04) for the ID group (n = 141), and .38 (+/- .04) for the HD group (n = 128, P = .919). The 2 groups did not differ in terms of prognostic factors and other therapeutic parameters. In conclusion, methotrexate infusions at 5 g/m(2) per 24 hours, compared with 1 g/m(2) per 36 hours, are not associated with increased disease control in relapsed childhood PBC acute lymphoblastic leukemia.

Submicroscopic bone marrow involvement in isolated extramedullary relapses in childhood acute lymphoblastic leukemia: a more precise definition of “isolated” and its possible clinical implications, a collaborative study of the Resistant Disease Committee of the International BFM study group

This study investigates the extent of bone marrow (BM) involvement at diagnosis of apparent isolated extramedullary (AIEM) relapses of childhood acute lymphoblastic leukemia (ALL) and its relation to prognosis. Sixty-four children with first AIEM relapse treated in Germany, Czech Republic, or France were included. Real-time quantitative polymerase chain reaction using T-cell receptor and immunoglobulin gene rearrangements provided a sensitive measure of submicroscopic BM involvement, which was detectable at a level of 10−4 or higher in 46 patients and less than 10−4 in 11 patients, and was nondetectable (sensitivity: 10−4) in 7 patients. In the total cohort, the probability of event-free survival (pEFS) for children with BM involvement of 10−4 or higher was 0.30 (0.09 ± SE) versus 0.60 (± 0.12) for those with less than 10−4 (P = .13). The cumulative incidence of subsequent relapse was 0.24 (± 0.01) for patients with BM involvement less than 10−4 and 0.65 (± 0.01) for those with 10−4 or higher (P = .012). Restricted to central nervous system (CNS) relapses, pEFS was 0.11 (± 0.09) for patients with BM involvement 10−4 or higher and 0.63 (± 0.17) for those with less than 10−4 (P = .053). CNS relapses were associated with a higher (≥ 10−4: 80%) submicroscopic BM involvement than testicular relapses (≥ 10−4: 57%, P = .08). In summary, we show marked heterogeneity of submicroscopic BM involvement at first AIEM relapse diagnosis in children with ALL, and demonstrate its possible prognostic relevance.

Superiority of allogeneic hematopoietic stem-cell transplantation compared with chemotherapy alone in high-risk childhood T-cell acute lymphoblastic leukemia: results from ALL-BFM 90 and 95

PURPOSE

The role of hematopoietic stem-cell transplantation (SCT) in first complete remission (CR1) for children with very high-risk (VHR) acute lymphoblastic leukemia (ALL) is still under critical discussion.

PATIENTS AND METHODS

In the ALL-Berlin-Frankfurt-Münster (BFM) 90 and ALL-BFM 95 trials, 387 patients were eligible for SCT if there was a matched sibling donor (MSD). T-cell ALL (T-ALL) patients with poor in vivo response to initial treatment represented the largest homogeneous subgroup within VHR patients.

RESULTS

Of 191 high-risk (HR) T-ALL patients, 179 patients (94%) achieved CR1. Twenty-three patients received an MSD-SCT. Furthermore, in trial ALL-BFM 95, eight matched unrelated donors (MUDs) and five mismatched family donors (MMFDs) were used. The median time to SCT was 5 months (range, 2.4 to 10.8 months) from diagnosis. The 5-year disease-free survival (DFS) was 67% +/- 8% for 36 patients who received an SCT in CR1 and 42% +/- 5% for the 120 patients treated with chemotherapy alone having an event-free survival time of at least the median time to transplantation (Mantel-Byar, P = .01). Overall survival (OS) rate for the SCT group was 67% +/- 8% at 5 years, whereas patients treated with chemotherapy alone had an OS rate of 47% +/- 5% at 5 years (Mantel-Byar, P = .01). Outcome of patients who received MSD-SCT versus MUD-/MMFD-SCT was comparable (DFS, 65% +/- 10% v 69% +/- 13%, respectively). However, relapses only occurred after MSD-SCT (eight of 23 patients), whereas treatment-related mortality only occurred after MUD-/MMFD-SCT (four of 13 patients).

CONCLUSION

SCT in CR1 is superior to treatment with chemotherapy alone for childhood HR-T-ALL.

In vivo control of acute lymphoblastic leukemia by immunostimulatory CpG oligonucleotides

Despite considerable success in treating newly diagnosed childhood acute lymphoblastic leukemia (ALL), relapsed disease remains a significant clinical challenge. Using a NOD/SCID mouse xenograft model, we report that immunostimulatory DNA oligonucleotides containing CpG motifs (CpG ODNs) stimulate significant immune activity against primary human ALL cells in vivo. The administration of CpG ODNs induced a significant reduction in systemic leukemia burden, mediated continued disease control, and significantly improved survival of mice with established human ALL. The death of leukemia cells in vivo was independent of the ability of ALL cells to respond directly to CpG ODNs and correlated with the production of IL-12p70, IFN-α, and IFN-γ by the host. In addition, depletion of natural killer cells by anti–asialo-GM1 treatment significantly reduced the in vivo antileukemic activity of CpG ODN. This antileukemia effect was not limited to the xenograft model because natural killer cell–dependent killing of ALL by human peripheral blood mononuclear cells (PBMCs) was also increased by CpG ODN stimulation. These results suggest that CpG ODNs have potential as therapeutic agents for the treatment of ALL.

Bone Marrow Transplantation Versus Prolonged Intensive Chemotherapy for Children With Acute Lymphoblastic Leukemia and an Initial Bone Marrow Relapse Within 12 Months of the Completion of Primary Therapy: Children's Oncology Group Study CCG-1941

Purpose

To compare conventional sibling bone marrow transplantation (CBMT), BMT with alternative donor (ABMT), and chemotherapy (CT) for children with acute lymphoblastic leukemia (ALL) and an early first marrow relapse.

Patients and Methods

After informed consent, 214 patients with ALL and early marrow relapse began multiagent induction therapy. One hundred sixty-three patients with fewer than 25% marrow blasts and count recovery at the end of induction (second remission [CR2]) were allocated by donor availability. Fifty patients with sibling donors were allocated to CBMT. Seventy-two patients were randomly allocated between ABMT and CT while 41 patients refused allocation.

Results

Overall, 3-year event free survival from entry is 19% ± 3%. Thirty-two of 50 CBMT patients (64%) and 19 of 37 ABMT patients (51%) underwent transplantation in CR2 with 3-year disease-free survival of 42% ± 7% and 29% ± 7%. The 3-year DFS is 29% ± 7%, 21% ± 7%, and 27% ± 8% for patients allocated to CBMT, ABMT, and CT, respectively. Contrary to protocol, 12 of 35 patients allocated to CT underwent BMT in CR2. Of these, five patients died after BMT and 5 patients relapsed.

Conclusion

More than one half of patients died, failed reinduction, or relapsed again before 3 months after CR2 (median time to BMT). Intent-to-treat pair-wise comparison of ABMT with CT, CT with CBMT, and CBMT with ABMT yields hazards of 1.2, 1.1, 0.8 with P values of .56, .80, and .36, respectively. Outcomes remain similar and poor for children with ALL and early marrow relapse. BMT is not a complete answer to the challenge of ALL and early marrow relapse.

Allogeneic stem cell transplantation in children with acute lymphoblastic leukemia after isolated central nervous system relapse: our experiences and review of the literature

The prognosis of patients with acute lymphoblastic leukemia (ALL) and central nervous system (CNS) relapse has historically been very poor. Although chemo-radiotherapy has improved outcomes, some patients still have a poor prognosis after CNS relapse. Therefore, allogeneic hematopoietic stem cell transplantation (allo-SCT) has recently become an option for treatment of CNS leukemia; however, information, particularly on the long-term outcome of transplant recipients, is limited. We performed allo-SCT in eight pediatric patients with ALL (n=7) or T-cell type non-Hodgkin's lymphoma (n=1), who had isolated CNS relapse. All patients survived for a median of 70.5 (range, 13-153) months after SCT. Sequelae developed late in some patients: mental retardation (IQ=47) in one patient, severe alopecia in two patients, limited chronic graft-versus-host-disease in three patients, and amenorrhea and/or hypothyroidism in three patients. Except for a pre-school child with post transplant CNS relapse, six out of seven patients show normal school/social performance. Our results clearly indicate a high cure rate of isolated CNS relapse by allo-SCT in pediatric lymphoid malignancies; however, there needs to be further studies to determine which are the appropriate candidates for transplantation and what is the best transplant regimen to achieve high cure rate and maintain good quality of life.

Hematopoietic stem cell transplantation after first marrow relapse of non-T, non-B acute lymphoblastic leukemia: a pediatric oncology group pilot feasibility study

BACKGROUND

Relapsed acute lymphoblastic leukemia (ALL) in children is associated with a poor outcome, especially for those patients whose relapse occurs during the first 36 months after diagnosis. The best therapy for these patients is not known. This study was designed to evaluate the feasibility of enrolling children with recurrent ALL in a standardized treatment protocol that included receipt of a hematopoietic stem cell transplant (HSCT).

PROCEDURE

Eligible patients with a bone marrow relapse of non-T, non-B ALL underwent a common induction and consolidation followed by receipt of either an allogeneic HSCT from a human leukocyte antigen (HLA)-identical sibling or an autologous HSCT purged with B-4 blocked ricin. A common conditioning regimen was used for all patients.

RESULTS

Twenty-eight patients from eight institutions were enrolled. Fourteen patients did not receive a transplant during the study, because of toxicity (4), relapse (1), inadequate purging (1), and parental or physician preference for an alternative donor transplant (8). Six patients received allogeneic HSCTs. Five of them have remained in remission for a median of 78 months. Eight patients received autologous HSCTs purged with B4-blocked ricin. Four have remained in remission for a median of 94 months. Of the nine patients who received alternative donor transplants, only two remain in remission.

CONCLUSION

We conclude that well designed and controlled prospective studies are necessary to define the role of HSCTs in children with recurrent ALL. In order to be successful, such studies must have the full support of participating centers. Autologous HSC transplantation may have a role in the treatment of relapsed ALL, but further studies are needed.

Long-term outcome in children with relapsed ALL by risk-stratified salvage therapy: results of trial acute lymphoblastic leukemia-relapse study of the Berlin-Frankfurt-Münster Group 87

PURPOSE

Approximately 20% of children with acute lymphoblastic leukemia (ALL) suffer a relapse, and their prognosis is unfavorable. Between 1987 and 1990, the multicenter trial Acute Lymphoblastic Leukemia-Relapse Study of the Berlin-Frankfurt-Münster Group (ALL-REZ BFM) 87 was conducted to establish a uniform treatment for these children in Germany and Austria.

PATIENTS AND METHODS

Of 207 registered patients, 183 patients were stratified into three groups according to the protocol: A, early bone marrow (BM) relapse (n = 56); B, late BM relapse (n = 101); C, isolated extramedullary relapse (n = 26). Treatment consisted of risk-adapted alternating short-course multiagent systemic and intrathecal chemotherapy, cranial irradiation, if indicated, and conventional maintenance therapy. Additionally, 24 patients with an exceptionally poor prognosis (early BM or any relapse of T-cell ALL) were treated with individual regimens. In 35 patients, stem-cell transplantation was performed.

RESULTS

The probability of event-free survival (EFS) and overall survival of all registered patients at 15 years was 0.30 +/- 0.03 and 0.37 +/- 0.03, respectively, with significant differences between the strategic groups (A, 0.18 +/- 0.05 and 0.20 +/- 0.05; B, 0.44 +/- 0.05 and 0.52 +/- 0.05; C, 0.35 +/- 0.09 and 0.42 +/- 0.10). Despite risk-adapted treatment, an early time point of relapse and T-lineage immunophenotype were significant predictors of inferior EFS in uni- and multivariate analyses.

CONCLUSION

With the ALL-REZ BFM 87 protocol, more than one-third of patients may be regarded as cured from recurrent ALL with second complete remissions lasting more than 10 years. Immunophenotype and time point of relapse are important prognostic factors that allow us to adapt more precisely treatment intensity to individual prognosis in future trials.

Childhood acute lymphoblastic leukaemia and relapse

Acute lymphoblastic leukaemia (ALL) is the most common childhood cancer. Treatment has improved but relapsed ALL remains more common than new cases of many 'common' paediatric malignancies. We have salvage regimens with substantial complete remission (CR) rates and increasing access to haematopoietic stem cell transplantation, but most patients who relapse die. We need better therapies. Insights into pharmacology may guide more effective use of existing agents. Novel agents with activity against resistant lymphoblasts offer an appealing strategy. However, most candidate agents fail, despite enthusiastic investigators, intriguing mechanisms of action and 'compelling' preclinical data. A number of existing combinations provide a 40% complete response rate in second or third relapse. Yet survival in third remission is <10%. Novel agents must, most likely, be integrated into multiagent combinations that provide a higher CR rate or better quality CR's than our conventional combinations in order to contribute substantially to cure. The march from bench to bedside requires careful consideration of the intermediate steps.

The Role of Cytotoxic Therapy with Hematopoietic Stem Cell Transplantation in the Therapy of Acute Lymphoblastic Leukemia in Children: An Evidence-Based Review

Evidence supporting the role of hematopoietic stem cell transplantation (SCT) in the therapy of acute lymphoblastic leukemia (ALL) in children is presented and critically evaluated in this systematic evidence-based review. Specific criteria were used for searching the published literature and for grading the quality and strength of the evidence and the strength of the treatment recommendations. Treatment recommendations based on the evidence are presented in a table in this review (Summary of Treatment Recommendations Made by the Expert Panel for Pediatric Acute Lymphoblastic Leukemia) and were reached unanimously by a panel of ALL experts. The priority areas of needed future research in pediatric ALL are unrelated marrow or blood donor versus unrelated cord blood donor allogeneic SCT; alternative, nonfamily allogeneic donor versus autologous SCT; better methods for identifying high-relapse-risk patients; assessments of the effect of current chemotherapy regimens on early relapse; and use of pre-SCT detection of minimal residual disease to predict post-SCT outcomes.

Outcome after first relapse in childhood acute lymphoblastic leukaemia - lessons from the United Kingdom R2 trial

A retrospective analysis of children with first relapse of acute lymphoblastic leukaemia (ALL), treated on the UKALL R2 protocol at four different hospitals, between June 1995 and December 2002 was performed. Of the 150 children 139 (93%) achieved a second complete remission. The overall survival (OS) and event-free survival (EFS) for the whole group was 56% and 47% respectively. The duration of first complete remission and immunophenotype, but not sites of relapse, were predictive for survival. Using the Berlin-Frankfürt-Münster risk stratification for relapsed ALL, the OS and EFS for standard, intermediate (IR) and high risk (HR) groups were 92% and 92%, 64% and 51%, and 14% and 15%, respectively; P < 0.0001 for both OS and EFS. In the IR group, those with a very early isolated central nervous system relapse also had a significantly worse outcome (P = 0.0001). Given the poor outcome of a second relapse, clear strategies are required to identify those in the IR group who will most benefit from stem cell transplantation (SCT). A higher proportion (16%) of induction failures in the HR group suggest the need for novel agents during this phase of treatment, but SCT was associated with a lower relapse rate and better outcome than those treated with chemotherapy alone.

Prognostic factors for relapsed childhood acute lymphoblastic leukemia: impact of allogeneic stem cell transplantation--a report from the Kyushu-Yamaguchi Children's Cancer Study Group

BACKGROUND

The treatment results of childhood acute lymphoblastic leukemia (ALL) with a first relapse were retrospectively analyzed to determine prognostic factors. In particular, an attempt was made to clarify whether stem cell transplantation (SCT) had any advantages over chemotherapy.

PROCEDURES

Of the 407 children with ALL diagnosed between 1984 and 1996, 117 suffered from a relapse before December 1999. The patients were treated differently according to the protocols of each institution. The potential prognostic factors examined were: the time of initial diagnosis, gender, immunophenotype of leukemic blasts and the NCI-risk classification at initial diagnosis, the site of relapse, the time of relapse (early: within 18 months after diagnosis, intermediate: other than either early or late relapse, late: later than 6 months after the discontinuation of front-line chemotherapy), and the treatment after relapse (chemotherapy alone and SCT).

RESULTS

A second complete remission (CR2) was achieved in 90 patients (77%) and thirty of them maintained CR2, thus resulting in an event-free survival rate (EFS) of 25.1% and an overall survival rate of 26.1%. The significant prognostic factors identified by a multivariate analysis included the time of relapse (EFS: early 16.2%, intermediate 23.9%, late 35.1%, P = 0.012) and the treatment after relapse (EFS: SCT 30.3%, chemotherapy 22.0%, P = 0.049). When patients with an isolated bone marrow relapse and continuous CR2 for more than 3 months were analyzed, the treatment in CR2 was the only independent prognostic factor (EFS: SCT 60.2%, chemotherapy 25.7%, P = 0.005).

CONCLUSIONS

In children with ALL and a first relapse, the time of relapse and the treatment after relapse were found to be independent prognostic factors. Allogeneic SCT in CR2 showed significantly better results than chemotherapy in patients with an isolated bone marrow relapse.

Factors affecting the outcome of stem cell transplantation from unrelated donors for childhood acute lymphoblastic leukemia in third remission

Between July 1990 and March 2002, 35 consecutive children with ALL in third complete remission (CR3) underwent stem cell transplantation (SCT) from unrelated donors (UD). All patients received CAMPATH-1M 5-20 mg daily for 5 days. Grafts were T-cell depleted in 30 patients, 29 by CAMPATH antibodies and one by CD34 selection. Median follow-up was 3.8 years (0.3-9.3). Event-free survival (EFS) at 3 years was 35% (SE 8%); relapse rate and transplant-related mortality (TRM) at 3 years was 42 and 23%. Short first complete remission (CR1) <2.5 years was associated with lower EFS (P=0.001), higher TRM (P=0.019) and higher relapse rate (P=0.023). Short second complete remission (CR2) <2.5 years was associated with lower EFS (P=0.003) and higher TRM (0.009). Higher relapse rate and lower EFS were associated with isolated first extramedullary relapse (P=0.019, 0.012). There was no significant difference in outcome between mismatched unrelated donor stem cell transplantation (MMUD-SCT) and matched unrelated donor stem cell transplantation (UD-SCT). We conclude that UD-SCT is an effective treatment of ALL in CR3. The outcome remains limited by TRM and a high relapse rate. Short duration of CR1 and of CR2 and extramedullary site at first relapse are particularly adverse. MMUD should also be considered in high-risk patients, since the outcome of MMUD appears similar to MUD.

Second induction in pediatric patients with recurrent acute lymphoid leukemia using DFCI-ALL protocols

Between 15% and 30% of children with acute lymphoblastic leukemia (ALL) experience disease recurrence. With the possible exception of patients presenting with late isolated extramedullary relapse, induction of second complete remission (CR) is employed as a stepping stone to allogeneic hematopoietic stem cell transplantation (HSCT). The authors report their institutional experience in the management of children with recurrent ALL using the Dana Farber Cancer Institute (DFCI) ALL protocol in patients treated initially with that same protocol. Successful reinduction was followed by allogeneic HSCT when possible. Between April 1986 and May 2003, 34 patients with recurrent ALL, treated at initial diagnosis with DFCI-ALL protocol therapy, were given the same protocol as repeat induction chemotherapy. The median age was 4.6 years at diagnosis and 7.1 years at recurrence. Median duration of CR1 was 30.3 months. Second CR was obtained in 29 (85%) patients. Twenty went on to allogeneic HSCT; 10 of them currently remain in CR. Two additional patients treated with chemotherapy without HSCT are also in continuous CR2. Overall, 13 (38%) of the 34 patients are alive with a median follow-up of 105 months. There were no toxic deaths due to the reinduction therapy. One child died of cardiac failure after autologous HSCT. The treatment of children with recurrent ALL using the DFCI-ALL protocol induction regimen after initial use of the same protocol is associated with a high rate of second CR with no excess toxicity. However, the overall prognosis in these patients remains unsatisfactory and needs to be improved.

Treatment of isolated central nervous system relapse in high-risk lymphoid malignancy with allogeneic bone marrow transplantation and extended intrathecal therapy

We performed allogeneic bone marrow transplantation (BMT) with an extended period of post-transplant intrathecal (IT) chemotherapy for five patients with acute lymphoblastic leukaemia and non-Hodgkin's lymphoma who had relapsed in the central nervous system either in the very early phase or more than twice. Post-transplant IT was scheduled for a total of 12 doses over 18 months. One patient was found to have subclinical leucoencephalopathy. Disease relapse occurred in one patient and the other patients remained in complete remission for 39-196 months post-BMT. The estimated event-free survival was 80 +/- 17.9% (standard error).

Clinical significance of minimal residual disease in childhood acute lymphoblastic leukemia after first relapse

Using flow cytometric techniques capable of detecting 0.01% leukemic cells, we prospectively studied minimal residual disease (MRD) in patients with acute lymphoblastic leukemia (ALL) after first relapse. At the end of remission reinduction, 41 patients had a bone marrow sample adequate for MRD studies; 35 of these were in morphologic remission. Of the 35 patients, 19 (54%) had MRD >/=0.01%, a finding that was associated with subsequent leukemia relapse. The 2-year cumulative incidence of second leukemia relapse was 70.2+/-12.3% for the 19 MRD-positive patients and 27.9+/-12.4% for the 16 MRD-negative patients (P=0.008). Among patients with a first relapse off therapy, 2-year second relapse rates were 49.1+/-17.8% in the 12 MRD-positive and 0% in the 11 MRD-negative patients (P=0.014); among those who received only chemotherapy after first relapse, the 2-year second relapse rates were 81.5+/-14.4% (n=12) and 25.0+/-13.1% (n=13), respectively (P=0.004). Time of first relapse and MRD were the only two significant predictors of outcome in a multivariate analysis. We conclude that MRD assays should be used to guide the selection of postremission therapy in patients with ALL in first relapse.

Busulfan and cyclophosphamide as a conditioning regimen for pediatric acute lymphoblastic leukemia patients undergoing bone marrow transplantation

Bone marrow transplantation (BMT) has become the standard therapy for children with relapsed acute lymphoblastic leukemia. The authors report their experience with histocompatible BMT for 52 children with acute lymphoblastic leukemia conditioned with a non-total body irradiation (TBI) regimen using busulfan and cyclophosphamide (Bu/Cy). The efficacy and long-term toxicity of the Bu/Cy regimen were determined. Overall survival was 35%. One-year, 3-year, and 7-year event-free survival rates were 54%, 33%, and 23%, respectively. Of the 52 BMT recipients, 26 relapsed. Thirteen of the relapsed patients received a second BMT and three were surviving as of this writing. The most frequent cause of death was leukemia relapse. An initial remission duration of less than 18 months was a factor in decreasing the event-free survival. The Bu/Cy regimen was well tolerated, with minimal transplant-related mortality. Neurocognitive function was tested before BMT and 1 year after BMT. When 1-year posttransplant neurocognitive test scores were compared with pretransplant scores, there was no decrease. However, there was a significant decrease in the pretransplant neurocognitive test scores in BMT recipients compared with their normal siblings. The use of Bu/Cy as a conditioning regimen for BMT does not appear to affect posttransplant neurocognitive function. Other long-term side effects, such as endocrinopathies and secondary malignancies, were also minimal. These data show that the Bu/Cy regimen is well tolerated, but the overall survival rate remains low.

Minimal residual disease prior to stem cell transplant for childhood acute lymphoblastic leukaemia

Allogeneic stem cell transplantation (SCT) is a highly effective therapy for childhood acute lymphoblastic leukaemia (ALL). Concerns about unnecessary toxicity and expense mean that SCT is currently largely reserved for children who cannot be cured with chemotherapy. Not surprisingly, many such children also fail SCT. Retrospective studies have shown that a single analysis of minimal residual disease (MRD) pre-SCT identified those at highest risk of relapse. It is now appropriate to call for the universal incorporation of standardized MRD testing into SCT protocols as the next step to maximize the clinical impact of this technology in ALL.

Improvement over time in outcome for children with acute lymphoblastic leukemia in second remission given hematopoietic stem cell transplantation from unrelated donors

Aims of this study were to verify whether reduction in transplant-related mortality (TRM) of children with acute lymphoblastic leukemia (ALL) in second complete remission (CR) given allogeneic hematopoietic stem cell transplantation (HSCT) from unrelated volunteers has occurred over time and to investigate the role of other variables on the probabilities of relapse, TRM and event-free survival (EFS). We compared results obtained in 26 children given HSCT before January 1998 with those of 37 patients transplanted beyond that date. In all donor-recipient pairs, histocompatibility was determined by serology for HLA-A and -B antigens and by high-resolution DNA typing for DRB1 antigen. High-resolution molecular typing of HLA class I antigens was employed in 20 of the 37 children transplanted more recently. Probability of both acute and chronic GVHD was comparable in the two groups of patients. In multivariate analysis, children transplanted before January 1998, those with T-lineage ALL and those experiencing grade II-IV acute GVHD had a higher relative risk of TRM at 6 months after transplantation. Relapse rate was unfavorably affected by a time interval between diagnosis and relapse <30 months. The 2-year probability of EFS for children transplanted before and after 1 January 1998 was 27% (10-44) and 58% (42-75), respectively (P = 0.02), this difference remaining significant in multivariate analysis. EFS of unrelated donor HSCT in children with ALL in second CR has improved in the last few years, mainly due to a decreased TRM. This information is of value for counseling of patients with relapsed ALL.