CD371-positive pediatric B-cell acute lymphoblastic leukemia: propensity to lineage switch and slow early response to treatment

ABSTRACT

In the effort to improve immunophenotyping and minimal residual disease (MRD) assessment in acute lymphoblastic leukemia (ALL), the international Berlin-Frankfurt-Münster (iBFM) Flow Network introduced the myelomonocytic marker CD371 for a large prospective characterization with a long follow-up. In the present study, we aimed to investigate the clinical and biological features of CD371-positive (CD371pos) pediatric B-cell precursor ALL (BCP-ALL). From June 2014 to February 2017, 1812 pediatric patients with newly diagnosed BCP-ALLs enrolled in trial AIEOP-BFM ALL 2009 were evaluated as part of either a screening (n = 843, Italian centers) or validation cohort (n = 969, other iBFM centers). Laboratory assessment at diagnosis consisted of morphological, immunophenotypic, and genetic analysis. Response assessment relied on morphology, multiparametric flow cytometry (MFC), and polymerase chain reaction (PCR)-MRD. At diagnosis, 160 of 1812 (8.8%) BCP-ALLs were CD371pos. This correlated with older age, lower ETV6::RUNX1 frequency, immunophenotypic immaturity (all P < .001), and strong expression of CD34 and of CD45 (P < .05). During induction therapy, CD371pos BCP-ALLs showed a transient myelomonocytic switch (mm-SW: up to 65.4% of samples at day 15) and an inferior response to chemotherapy (slow early response, P < .001). However, the 5-year event-free survival was 88.3%. Among 420 patients from the validation cohort, 27 of 28 (96.4%) cases positive for DUX4-fusions were CD371pos. In conclusion, in the largest pediatric cohort, CD371 is the most sensitive marker of transient mm-SW, whose recognition is essential for proper MFC MRD assessment. CD371pos is associated to poor early treatment response, although a good outcome can be reached after MRD-based ALL-related therapies.

Identification of diagnosis and prognosis gene markers in B-ALL with ETV6-RUNX1 fusion by integrated bioinformatics analysis

B-acute lymphoblastic leukemia (B-ALL) is characterized by clonal expansion of immature B-lymphocytes in the bone marrow, blood, or other tissues. Chromosomal translocations have often been reported in B-ALL, which are important for its prognosis. B-ALL patients with ETV6-RUNX1 fusion have favorable outcomes, but the mechanisms remain to be clarified. In the present study, we crossed the selected WGCNA module genes and differential expression genes to obtain core genes, and random forest algorithm, a type of supervised learning analysis, was conducted to evaluate the importance of those core genes in distinguishing B-ALL samples with ETV6-RUNX2 fusion with extracting 5 genes as gene markers for ETV6-RUNX2 fusion. Moreover, we calculated the immune infiltration profiles and screened out the ETV6-RUNX2 association immune cells using the CIBERSORT algorithm. In conclusion, combined with various solid informatics methods, we depicted the underlying molecular and immune mechanism of ETV6-RUNX2 fusion and providing potential biological targets for diagnosing and treating B-ALL in the future.

Interventions and outcomes of adult patients with B-ALL progressing after CD19 chimeric antigen receptor T-cell therapy

CD19-targeted chimeric antigen receptor (CAR) T-cell therapy has become a breakthrough treatment of patients with relapsed/refractory B-cell acute lymphoblastic leukemia (B-ALL). However, despite the high initial response rate, the majority of adult patients with B-ALL progress after CD19 CAR T-cell therapy. Data on the natural history, management, and outcome of adult B-ALL progressing after CD19 CAR T cells have not been described in detail. Herein, we report comprehensive data of 38 adult patients with B-ALL who progressed after CD19 CAR T therapy at our institution. The median time to progression after CAR T-cell therapy was 5.5 months. Median survival after post-CAR T progression was 7.5 months. A high disease burden at the time of CAR T-cell infusion was significantly associated with risk of post-CAR T progression. Thirty patients (79%) received salvage treatment of post-CAR T disease progression, and 13 patients (43%) achieved complete remission (CR), but remission duration was short. Notably, 7 (58.3%) of 12 patients achieved CR after blinatumomab and/or inotuzumab administered following post-CAR T failure. Multivariate analysis revealed that a longer remission duration from CAR T cells was associated with superior survival after progression following CAR T-cell therapy. In summary, overall prognosis of adult B-ALL patients progressing after CD19 CAR T cells was poor, although a subset of patients achieved sustained remissions to salvage treatments, including blinatumomab, inotuzumab, and reinfusion of CAR T cells. Novel therapeutic strategies are needed to reduce risk of progression after CAR T-cell therapy and improve outcomes of these patients.

KTE-X19 for relapsed or refractory adult B-cell acute lymphoblastic leukaemia: phase 2 results of the single-arm, open-label, multicentre ZUMA-3 study

BACKGROUND

Despite treatment with novel therapies and allogeneic stem-cell transplant (allo-SCT) consolidation, outcomes in adult patients with relapsed or refractory B-precursor acute lymphoblastic leukaemia remain poor, underlining the need for more effective therapies.

METHODS

We report the pivotal phase 2 results of ZUMA-3, an international, multicentre, single-arm, open-label study evaluating the efficacy and safety of the autologous anti-CD19 chimeric antigen receptor (CAR) T-cell therapy KTE-X19 in adult patients with relapsed or refractory B-precursor acute lymphoblastic leukaemia. Patients were enrolled at 25 sites in the USA, Canada, and Europe. Eligible patients were aged 18 years or older, with Eastern Cooperative Oncology Group performance status of 0-1, and morphological disease in the bone marrow (>5% blasts). After leukapheresis and conditioning chemotherapy, patients received a single KTE-X19 infusion (1 × 10⁶ CAR T cells per kg bodyweight). The primary endpoint was the rate of overall complete remission or complete remission with incomplete haematological recovery by central assessment. Duration of remission and relapse-free survival, overall survival, minimal residual disease (MRD) negativity rate, and allo-SCT rate were assessed as secondary endpoints. Efficacy and safety analyses were done in the treated population (all patients who received a dose of KTE-X19). This study is registered with ClinicalTrials.gov, NCT02614066.

FINDINGS

Between Oct 1, 2018, and Oct 9, 2019, 71 patients were enrolled and underwent leukapheresis. KTE-X19 was successfully manufactured for 65 (92%) patients and administered to 55 (77%). The median age of treated patients was 40 years (IQR 28-52). At the median follow-up of 16·4 months (13·8-19·6), 39 patients (71%; 95% CI 57-82, p<0·0001) had complete remission or complete remission with incomplete haematological recovery, with 31 (56%) patients reaching complete remission. Median duration of remission was 12·8 months (95% CI 8·7-not estimable), median relapse-free survival was 11·6 months (2·7-15·5), and median overall survival was 18·2 months (15·9-not estimable). Among responders, the median overall survival was not reached, and 38 (97%) patients had MRD negativity. Ten (18%) patients received allo-SCT consolidation after KTE-X19 infusion. The most common adverse events of grade 3 or higher were anaemia (27 [49%] patients) and pyrexia (20 [36%] patients). 14 (25%) patients had infections of grade 3 or higher. Two grade 5 KTE-X19-related events occurred (brain herniation and septic shock). Cytokine release syndrome of grade 3 or higher occurred in 13 (24%) patients and neurological events of grade 3 or higher occurred in 14 (25%) patients.

INTERPRETATION

KTE-X19 showed a high rate of complete remission or complete remission with incomplete haematological recovery in adult patients with relapsed or refractory B-precursor acute lymphoblastic leukaemia, with the median overall survival not reached in responding patients, and a manageable safety profile. These findings indicate that KTE-X19 has the potential to confer long-term clinical benefit to these patients.

FUNDING

Kite, a Gilead Company.

Prognostic factors for CNS control in children with acute lymphoblastic leukemia treated without cranial irradiation

To identify the prognostic factors that are useful to improve central nervous system (CNS) control in children with acute lymphoblastic leukemia (ALL), we analyzed the outcome of 7640 consecutive patients treated on Chinese Children's Cancer Group ALL-2015 protocol between 2015 and 2019. This protocol featured prephase dexamethasone treatment before conventional remission induction and subsequent risk-directed therapy, including 16 to 22 triple intrathecal treatments, without prophylactic cranial irradiation. The 5-year event-free survival was 80.3% (95% confidence interval [CI], 78.9-81.7), and overall survival 91.1% (95% CI, 90.1-92.1). The cumulative risk of isolated CNS relapse was 1.9% (95% CI, 1.5-2.3), and any CNS relapse 2.7% (95% CI, 2.2-3.2). The isolated CNS relapse rate was significantly lower in patients with B-cell ALL (B-ALL) than in those with T-cell ALL (T-ALL) (1.6%; 95% CI, 1.2-2.0 vs 4.6%; 95% CI, 2.9-6.3; P < .001). Independent risk factors for isolated CNS relapse included male sex (hazard ratio [HR], 1.8; 95% CI, 1.1-3.0; P = .03), the presence of BCR-ABL1 fusion (HR, 3.8; 95% CI, 2.0-7.3; P < .001) in B-ALL, and presenting leukocyte count ≥50×109/L (HR, 4.3; 95% CI, 1.5-12.2; P = .007) in T-ALL. Significantly lower isolated CNS relapse was associated with the use of total intravenous anesthesia during intrathecal therapy (HR, 0.2; 95% CI, 0.04-0.7; P = .02) and flow cytometry examination of diagnostic cerebrospinal fluid (CSF) (HR, 0.2; 95% CI, 0.06-0.6; P = .006) among patients with B-ALL. Prephase dexamethasone treatment, delayed intrathecal therapy, use of total intravenous anesthesia during intrathecal therapy, and flow cytometry examination of diagnostic CSF may improve CNS control in childhood ALL. This trial was registered with the Chinese Clinical Trial Registry (ChiCTR-IPR-14005706).

Risk factors and outcomes in children with high-risk B-cell precursor and T-cell relapsed acute lymphoblastic leukaemia: combined analysis of ALLR3 and ALL-REZ BFM 2002 clinical trials

AIM

Outcomes of children with high-risk (HR) relapsed acute lymphoblastic leukaemia (ALL) (N = 393), recruited to ALLR3 and ALL-REZ BFM 2002 trials, were analysed. Minimal residual disease (MRD) was assessed after induction and at predetermined time points until haematopoietic stem cell transplantation (SCT).

METHODS

Genetic analyses included karyotype, copy-number alterations and mutation analyses. Ten-year survivals were analysed using Kaplan-Meier and Cox models for multivariable analyses.

RESULTS

Outcomes of patients were comparable in ALLR3 and ALL-REZ BFM 2002. The event-free survival of B-cell precursor (BCP) and T-cell ALL (T-ALL) was 22.6% and 26.2% (P = 0.94), respectively, and the overall survival (OS) was 32.6% and 28.2% (P = 0.11), respectively. Induction failures (38%) were associated with deletions of NR3C1 (P = 0.002) and BTG1 (P = 0.03) in BCP-ALL. The disease-free survival (DFS) and OS in patients with good vs poor MRD responses were 57.4% vs 22.6% (P < 0.0001) and 57.8% vs 32.0% (P = 0.0004), respectively. For BCP- and T-ALL, the post-SCT DFS and OS were 42.1% and 56.8% (P = 0.26) and 51.6% and 55.4% (P = 0.67), respectively. The cumulative incidences of post-SCT relapse for BCP- and T-ALL were 36.9% and 17.8% (P = 0.012) and of death were 10.7% and 25.5% (P = 0.013), respectively. Determinants of outcomes after SCT were acute graft versus host disease, pre-SCT MRD (≥10-3), HR cytogenetics and TP53 alterations in BCP-ALL.

CONCLUSION

Improvements in outcomes for HR ALL relapses require novel compounds in induction therapy to improve remission rates and immune targeted therapy after induction to maintain remission after SCT.

TRIAL REGISTRATION

ALLR3: NCT00967057; ALL REZ-BFM 2002: NCT00114348.

Integrating CAR T-Cell Therapy and Transplantation: Comparisons of Safety and Long-Term Efficacy of Allogeneic Hematopoietic Stem Cell Transplantation After CAR T-Cell or Chemotherapy-Based Complete Remission in B-Cell Acute Lymphoblastic Leukemia

Patients often undergo consolidation allogeneic hematopoietic stem cell transplantation (allo-HSCT) to maintain long-term remission following chimeric antigen receptor (CAR) T-cell therapy. Comparisons of safety and efficacy of allo-HSCT following complete remission (CR) achieved by CAR-T therapy versus by chemotherapy for B-cell acute lymphoblastic leukemia (B-ALL) has not been reported. We performed a parallel comparison of transplant outcomes in 105 consecutive B-ALL patients who received allo-HSCT after achieving CR with CAR-T therapy (n=27) or with chemotherapy (n=78). The CAR-T-allo-HSCT group had more patients in second CR compared to the chemotherapy-allo-HSCT group (78% vs. 37%; p<0.01) and more with complex cytogenetics (44% vs. 6%; p<0.001) but the proportion of patients with pre-transplant minimal residual disease (MRD) was similar. The median follow-up time was 49 months (range: 25-54 months). The CAR-T cohort had a higher incidence of Grade II-IV acute graft-versus-host disease (aGVHD 48.1% [95% CI: 46.1-50.1%] vs. 25.6% [95%CI: 25.2-26.0%]; p=0.016). The incidence of Grade III-IV aGVHD was similar in both groups (11.1% vs.11.5%, p=0.945). The overall incidence of chronic GVHD in the CAR-T group was higher compared to the chemotherapy group (73.3% [95%CI: 71.3-75.3%] vs. 55.0% [95%CI: 54.2-55.8%], p=0.107), but the rate of extensive chronic GVHD was similar (11.1% vs.11.9%, p=0.964). Efficacy measures 4 years following transplant were all similar in the CAR-T vs. the chemotherapy groups: cumulative incidences of relapse (CIR; 11.1% vs.12.8%; p=0.84), cumulative incidences of non-relapse mortality (NRM; 18.7% vs. 23.1%; p=0.641) leukemia-free survival (LFS; 70.2% vs. 64.1%; p=0.63) and overall survival (OS; 70.2% vs. 65.4%; p=0.681). We found that pre-transplant MRD-negative CR predicted a lower CIR and a higher LFS compared with MRD-positive CR. In conclusion, our data indicate that, in B-ALL patients, similar clinical safety outcomes could be achieved with either CD19 CAR T-cell therapy followed by allo-HSCT or chemotherapy followed by allo-HSCT. Despite the inclusion of more patients with advanced diseases in the CAR-T group, the 4-year LFS and OS achieved with CAR T-cells followed by allo-HSCT were as remarkable as those achieved with chemotherapy followed by allo-HSCT. Further confirmation of these results requires larger, randomized clinical trials.

Efficacy and safety of humanized anti-CD19-CAR-T therapy following intensive lymphodepleting chemotherapy for refractory/relapsed B acute lymphoblastic leukaemia

We studied the efficacy and safety of humanized CAR-T therapy following intensive chemotherapy for refractory/relapsed (R/R) acute lymphoblastic leukaemia (B-ALL). Twenty-three patients with R/R B-ALL were pretreated with intensive chemotherapy (fludarabine combined with medium-dose cytarabine) 12 days before CAR-T therapy. Adverse events (AEs), curative effects, infection indicators and cytokine release syndrome (CRS) were monitored. Each of the 23 patients received a dose of 1·0 × 10⁶ cells/kg CAR-T cell infusion on day 0. After 14 days, 19 patients (82·61%) achieved complete response (CR) or CR with incomplete count recovery. No survival benefit was achieved with consolidative haematopoietic stem-cell transplantation (HSCT), with a median follow-up of 14·0 months (range, 1·5-21·0 months). The notable AEs were grade 1-2 CRS in 18 patients, while the other five patients were grade 3 CRS. No patients died of CRS. Only one patient died of respiratory failure due to cytomegalovirus infection 24 days after infusion. The proportion of leukaemic cells in bone marrow on infusion day and the peaks of IL-6, TNF-α and IL-8 levels were correlated with CRS levels. A lower disease burden was achieved by intensive lymphodepleting chemotherapy, and the subsequent CAR-T therapy had a high response and manageable toxicity. Trial registration: The patients were enrolled in a clinical trial of ChiCTR-ONN-16009862, and ChiCTR1800019622.

Inotuzumab: from preclinical development to success in B-cell acute lymphoblastic leukemia

Inotuzumab ozogamicin (InO) is a recently US Food and Drug Administration-approved antibody-drug conjugate for the treatment of relapsed/refractory B-cell acute lymphoblastic leukemia (ALL). InO consists of a CD22-targeting immunoglobulin G4 humanized monoclonal antibody conjugated to calicheamicin. Although initially developed for the treatment of non-Hodgkin lymphoma (NHL) because of activity in preclinical models and high response rates in indolent lymphomas, a phase 3 trial was negative and further development focused on CD22+ ALL. Although results in NHL were disappointing, parallel testing in early-phase trials of CD22+ ALL demonstrated feasibility and efficacy. Subsequently, the randomized phase 3 Study Of Inotuzumab Ozogamicin Versus Investigator's Choice Of Chemotherapy In Patients With Relapsed Or Refractory Acute Lymphoblastic Leukemia trial showed that InO was superior to standard of care regimens with a significantly improved complete remission (CR) rate in patients with relapsed/refractory disease (80.7% vs 29.4%, P < .001). Patients achieving CR with InO also had a significantly higher rate of undetectable minimal residual disease compared with chemotherapy (78.4% vs 28.1%, P < .001). InO-specific side effects, including veno-occlusive disease, have been an ongoing area of concern, and consensus guidelines for minimizing toxicities are now available. Ongoing trials are investigating the combination of InO with other agents in the relapse setting and the addition of InO to frontline therapy. This review details the preclinical and clinical development of InO, focusing on how best to use it and future directions for further development.

Clinical and molecular characteristics of MEF2D fusion-positive B-cell precursor acute lymphoblastic leukemia in childhood, including a novel translocation resulting in MEF2D-HNRNPH1 gene fusion

Fusion genes involving MEF2D have recently been identified in precursor B-cell acute lymphoblastic leukemia, mutually exclusive of the common risk stratifying genetic abnormalities, although their true incidence and associated clinical characteristics remain unknown. We identified 16 cases of acute lymphoblastic leukemia and 1 of lymphoma harboring MEF2D fusions, including MEF2D-BCL9 (n=10), MEF2D-HNRNPUL1 (n=6), and one novel MEF2D-HNRNPH1 fusion. The incidence of MEF2D fusions overall was 2.4% among consecutive precursor B-cell acute lymphoblastic leukemia patients enrolled onto a single clinical trial. They frequently showed a cytoplasmic μ chain-positive pre-B immunophenotype, and often expressed an aberrant CD5 antigen. Besides up- and down-regulation of HDAC9 and MEF2C, elevated GATA3 expression was also a characteristic feature of MEF2D fusion-positive patients. Mutations of PHF6, recurrent in T-cell acute lymphoblastic leukemia, also showed an unexpectedly high frequency (50%) in these patients. MEF2D fusion-positive patients were older (median age 9 years) with elevated WBC counts (median: 27,300/ml) at presentation and, as a result, were mostly classified as NCI high risk. Although they responded well to steroid treatment, MEF2D fusion-positive patients showed a significantly worse outcome, with 53.3% relapse and subsequent death. Stem cell transplantation was ineffective as salvage therapy. Interestingly, relapse was frequently associated with the presence of CDKN2A/CDKN2B gene deletions. Our observations indicate that MEF2D fusions comprise a distinct subgroup of precursor B-cell acute lymphoblastic leukemia with a characteristic immunophenotype and gene expression signature, associated with distinct clinical features.

Clinical Pharmacology of Tisagenlecleucel in B-cell Acute Lymphoblastic Leukemia

PURPOSE

Tisagenlecleucel is an anti-CD19 chimeric antigen receptor (CAR19) T-cell therapy approved for the treatment of children and young adults with relapsed/refractory (r/r) B-cell acute lymphoblastic leukemia (B-ALL).

PATIENTS AND METHODS

We evaluated the cellular kinetics of tisagenlecleucel, the effect of patient factors, humoral immunogenicity, and manufacturing attributes on its kinetics, and exposure-response analysis for efficacy, safety and pharmacodynamic endpoints in 79 patients across two studies in pediatric B-ALL (ELIANA and ENSIGN).

RESULTS

Using quantitative polymerase chain reaction to quantify levels of tisagenlecleucel transgene, responders (N = 62) had ≈2-fold higher tisagenlecleucel expansion in peripheral blood than nonresponders (N = 8; 74% and 104% higher geometric mean Cmax and AUC0-28d, respectively) with persistence measurable beyond 2 years in responding patients. Cmax increased with occurrence and severity of cytokine release syndrome (CRS). Tisagenlecleucel continued to expand and persist following tocilizumab, used to manage CRS. Patients with B-cell recovery within 6 months had earlier loss of the transgene compared with patients with sustained clinical response. Clinical responses were seen across the entire dose range evaluated (patients ≤50 kg: 0.2 to 5.0 × 10⁶/kg; patients >50 kg: 0.1 to 2.5 × 10⁸ CAR-positive viable T cells) with no relationship between dose and safety. Neither preexisting nor treatment-induced antimurine CAR19 antibodies affected the persistence or clinical response.

CONCLUSIONS

Response to tisagenlecleucel was associated with increased expansion across a wide dose range. These results highlight the importance of cellular kinetics in understanding determinants of response to chimeric antigen receptor T-cell therapy.

The correlation between Pax5 deletion and patients survival in Iranian children with precursor B-cell acute lymphocytic leukemia

Despite advances in treatment, children with acute lymphoblastic leukemia (ALL) still experience drug resistance and relapse. Several gene mutations are involved in the onset of this disease and resistance to therapy. The present study examines the incidence of IKZF1, CDKN2A/B, PAX5, EBF1, ETV6, BTG1, RB1, JAK2, and Xp22.33 gene deletions/duplications associated with pediatric ALL in Iran and investigates the possible effect of these mutations on drug resistance. Three-year disease-free survival (3DFS) was evaluated for children diagnosed with Philadelphia negative precursor-B-cell ALL hospitalized at Sayed-al-Shohada Hospital, Isfahan-Iran, from January 2009 until December 2012. DNA was extracted from bone marrow slides, and ALL correlated gene deletions and duplications were measured using Multiplex Ligation-dependent Probe Amplification (MLPA) method. The correlation between gene mutations and 3DFS was then assessed. Among the nine aforementioned investigated genes, 63% of samples showed at least one gene mutation. At least two concomitant genomic mutations were observed in 42% of samples. Pax5 deletion was the most prevalent gene mutation observed in 45% of cases, and showed significant negative impact on response to treatment. CDKN2A/B (9p21.3) gene deletion, and ETV6 (12p13.2) gene duplication also demonstrated negative effect on patient survival and contributed to a worse prognosis if concomitant with Pax5 gene deletion. ALL patients with one of the gene deletions including Pax5  and CDKN2A/B (9p21.3) or ETV6 (12p13.2) gene duplication are classified as high-risk patients and need more intensified protocols of treatment to improve their chance of survival.

CRLF2-Positive B-Cell Acute Lymphoblastic Leukemia in Adult Patients: A Single-Institution Experience

Objectives

Cytokine receptor-like factor 2 ( CRLF2 ) rearrangement is found in approximately 50% of pediatric Ph-like B-cell acute lymphoblastic leukemia (B-ALL), and around 50% of CRLF2 + cases harbor JAK mutations. We analyzed CRLF2 expression and studied its correlation with CRLF2 rearrangement in adult patients with B-ALL.

Methods

Multiparameter flow cytometry (MFC) was performed consecutively in 126 patients.

Results

CRLF2 overexpression was detected in 30 (27%) patients, 28 (41%) of 69 patients with B-ALL not otherwise specified, 14 (21%) of 67 untreated patients, and 16 (27%) of 59 patients with relapsed B-ALL, with the highest among Hispanic patients (25/55, 45%). Of CRLF2+ cases, 21 (100%) of 21 cases showed CRLF2 rearrangement by fluorescence in situ hybridization, preferentially involving IGH@CRLF2 (15/15). The entire coding region of JAK2 was sequenced in 14 patients with CRLF2+ B-ALL, and nine (64%) were positive for JAK2 mutations.

Conclusions

MFC allows a rapid, inexpensive, and reliable detection of B-ALL with CRLF2 rearrangement that would further facilitate testing for JAK2 mutations for targetable therapy.

Blinatumomab versus Chemotherapy for Advanced Acute Lymphoblastic Leukemia

BACKGROUND

Blinatumomab, a bispecific monoclonal antibody construct that enables CD3-positive T cells to recognize and eliminate CD19-positive acute lymphoblastic leukemia (ALL) blasts, was approved for use in patients with relapsed or refractory B-cell precursor ALL on the basis of single-group trials that showed efficacy and manageable toxic effects.

METHODS

In this multi-institutional phase 3 trial, we randomly assigned adults with heavily pretreated B-cell precursor ALL, in a 2:1 ratio, to receive either blinatumomab or standard-of-care chemotherapy. The primary end point was overall survival.

RESULTS

Of the 405 patients who were randomly assigned to receive blinatumomab (271 patients) or chemotherapy (134 patients), 376 patients received at least one dose. Overall survival was significantly longer in the blinatumomab group than in the chemotherapy group. The median overall survival was 7.7 months in the blinatumomab group and 4.0 months in the chemotherapy group (hazard ratio for death with blinatumomab vs. chemotherapy, 0.71; 95% confidence interval [CI], 0.55 to 0.93; P=0.01). Remission rates within 12 weeks after treatment initiation were significantly higher in the blinatumomab group than in the chemotherapy group, both with respect to complete remission with full hematologic recovery (34% vs. 16%, P<0.001) and with respect to complete remission with full, partial, or incomplete hematologic recovery (44% vs. 25%, P<0.001). Treatment with blinatumomab resulted in a higher rate of event-free survival than that with chemotherapy (6-month estimates, 31% vs. 12%; hazard ratio for an event of relapse after achieving a complete remission with full, partial, or incomplete hematologic recovery, or death, 0.55; 95% CI, 0.43 to 0.71; P<0.001), as well as a longer median duration of remission (7.3 vs. 4.6 months). A total of 24% of the patients in each treatment group underwent allogeneic stem-cell transplantation. Adverse events of grade 3 or higher were reported in 87% of the patients in the blinatumomab group and in 92% of the patients in the chemotherapy group.

CONCLUSIONS

Treatment with blinatumomab resulted in significantly longer overall survival than chemotherapy among adult patients with relapsed or refractory B-cell precursor ALL. (Funded by Amgen; TOWER ClinicalTrials.gov number, NCT02013167 .).

International reference analysis of outcomes in adults with B-precursor Ph-negative relapsed/refractory acute lymphoblastic leukemia

Adults with relapsed/refractory acute lymphoblastic leukemia have an unfavourable prognosis, which is influenced by disease and patient characteristics. To further evaluate these characteristics, a retrospective analysis of 1,706 adult patients with Ph-negative relapsed/refractory B-precursor acute lymphoblastic leukemia diagnosed between 1990-2013 was conducted using data reflecting the standard of care from 11 study groups and large centers in Europe and the United States. Outcomes included complete remission, overall survival, and realization of stem cell transplantation after salvage treatment. The overall complete remission rate after first salvage was 40%, ranging from 35%-41% across disease status categories (primary refractory, relapsed with or without prior transplant), and was lower after second (21%) and third or greater (11%) salvage. The overall complete remission rate was higher for patients diagnosed from 2005 onward (45%, 95% CI: 39%-50%). One- and three-year survival rates after first, second, and third or greater salvage were 26% and 11%, 18% and 6%, and 15% and 4%, respectively, and rates were 2%-5% higher among patients diagnosed from 2005. Prognostic factors included younger age, longer duration of first remission, and lower white blood cell counts at primary diagnosis. This large dataset can provide detailed reference outcomes for patients with relapsed/refractory Ph-negative B-precursor acute lymphoblastic leukemia. clinicaltrials.gov identifier: 02003612.

[Prognostic value of bone marrow hematogones in childhood B-lineage acute lymphoblastic leukemia]

OBJECTIVE

To study the prognostic value of hematogones (HGs) for childhood B-lineage acute lymphoblastic leukemia (B-ALL) during consolidation chemotherapy.

METHODS

A retrospective analysis was conducted for 196 children with newly-diagnosed B-ALL. They were divided into high-risk group (n=55), intermediate-risk group (n=69), and low-risk group (n=72) by risk stratification, and into complete remission group (n=165) and relapse group (n=31) by clinical outcome. The European BIOMED-1 standard flow cytometry for minimal residual disease (MRD) was used to determine the number of HGs during consolidation chemotherapy. The Kaplan-Meier survival curve was used to assess event-free survival (EFS).

RESULTS

The high-risk group had a significantly lower number of HGs than the intermediate-risk and low-risk groups (P<0.05). The number of HGs in the complete remission group was significantly higher than in the relapse group (P<0.05). The children with HGs ≤1.0% had a significantly lower EFS than those with HGs <1.0% (P<0.05).

CONCLUSIONS

HGs can be used to assess the treatment outcome and prognosis in children with B-ALL, and proliferation of HGs reflects the good effect of chemotherapy in such children.

[Significance of PAX5 deletion in childhood B-lineage acute lymphoblastic leukemia without reproducible chromosomal abnormalities]

OBJECTIVE

To identify the incidence of PAX5 deletion in childhood B-lineage acute lymphoblastic leukemia (B-ALL) without reproducible chromosomal abnormalities and to investigate the association between PAX5 abnormalities and prognosis of ALL.

METHODS

Multiplex ligation-dependent probe amplification was used to determine the copy numbers of PAX5 gene in children newly diagnosed with B-ALL without reproducible chromosomal abnormalities between April 2008 and April 2013 and controls (children with non-hematologic diseases or tumors). The patients were classifiied into deletion group and non-deletion group based on the presence of PAX5 deletion.

RESULTS

Eighteen (21%) out of 86 children with B-ALL had PAX5 deletion. The deletion group had a significantly higher total white blood cell count at diagnosis than the non-deletion group (P=0.001). The Kaplan-Meier analysis demonstrated that the deletion group had a significantly lower disease-free survival (DFS) rate than the non-deletion group (0.69±0.12 vs 0.90±0.04; P=0.017), but there was no significant difference in the overall survival rate between the two groups (P=0.128). The Cox analysis showed that PAX5 deletion was a risk factor for DFS (P=0.03).

CONCLUSIONS

PAX5 deletion is an independent risk factor for DFS in B-ALL children without reproducible chromosomal abnormalities.

[Significance of IKZF1 gene copy number abnormalities in BCR/ABL-negative B-lineage acute lymphoblastic leukemia in children]

OBJECTIVE

To identify IKZF1 gene copy number abnormalities in BCR/ABL-negative B-lineage acute lymphoblastic leukemia (B-ALL) in children, and to investigate the association between such abnormalities and prognosis.

METHODS

Multiplex ligation-dependent probe amplification (MLPA) was applied to detect IKZF1 gene copy number abnormalities in 180 children diagnosed with BCR/ABL-negative B-ALL. These children were classified into IKZF1 deletion group and IKZF1 normal group according to the presence or absence of IKZF1 gene deletion. The association between IKZF1 copy number abnormalities and prognosis of children with BCR/ABL-negative B-ALL was analyzed retrospectively.

RESULTS

Among 180 children, 27 (15.0%) had IKZF1 deletion; among the 27 children, 4 had complete deletions of 8 exons of IKZF1 gene, 17 had deletion of exon 1, 3 had deletions of exons 4-7, and 3 children had deletions of exons 2-7. Compared with those in the IKZF1 normal group, children in the IKZF1 deletion group had higher white blood cell (WBC) count and percentage of individuals with high risk of minimal residual disease at the first visit. IKZF1 deletions often occurred in BCR/ABL-negative children with no special fusion gene abnormalities. They were frequently accompanied by abnormalities in chromosomes 11, 8, 5, 7, and 21. The analysis with Kaplan-Meier method showed that disease-free survival (DFS) in the IKZF1 deletion group was significantly lower than that in the IKZF1 normal group (0.740 ± 0.096 vs 0.905 ± 0.034; P=0.002). Cox analysis showed that after exclusion of sex, age, initial WBC count, cerebrospinal fluid state at the first visit, prednisone response, and chromosome karyotype, IKZF1 deletion still affected the children's DFS (P<0.05).

CONCLUSIONS

Some children with BCR/ABL-negative B-ALL have IKZF1 deletion, and IKZF1 deletion is an independent risk factor for DFS in children with BCR/ABL-negative B-ALL.

Antibodies: Immunoconjugates and autologous cellular therapy in acute lymphoblastic leukemia

Using a case study of a 57-year-old man with relapsed/refractory precursor-B (pre-B) acute lymphoblastic leukemia (ALL), this review discusses treatment with immunoconjugates and autologous therapy in acute ALL. Three therapies--blinatumomab, inotuzumab, and CAR T cells--are considered here, each with advantages in specific clinical situations. These therapies represent some of the exciting advances that have been made in the treatment of ALL over the last several years.

Minimal residual disease-based treatment is adequate for relapse-prone childhood acute lymphoblastic leukemia with an intrachromosomal amplification of chromosome 21: the experience of the ALL-BFM 2000 trial

BACKGROUND

Recently, the UK CCLG and COG reported that an intrachromosomal amplification of chromosome 21 (iAMP21) in acute lymphoblastic leukemia (ALL) loses its adverse prognostic impact with intensified therapy.

PATIENT AND METHODS

We evaluated the prognosis of iAMP21 among patients from the ALL-BFM (Berlin-Frankfurt-Münster) 2000 trial with 46 of 2 637 (2%) patients iAMP21+.

RESULTS

8-year event-free-survival (EFS, 64 ± 8% vs. 81 ± 1%, p=0.0026) and cumulative incidence of relapse (CIR, 29 ± 8% vs. 14 ± 1%, p=0.008) of the iAMP21 cases were significantly worse compared with non-iAMP21 patients. Within the MRD low-risk group, iAMP21 cases (n=14) had an inferior 8-year EFS (76 ± 12% vs. 92 ± 1%, p=0.0081), but no increased CIR (10 ± 10% vs. 6 ± 1%, p=0.624). Within the MRD intermediate-risk group, iAMP21 cases (n=27) had a worse 8-year EFS (56 ± 11% vs. 78 ± 2%, p=0.0077) and CIR (44 ± 11% vs. 20 ± 2%, p=0.003) with 6/10 relapses occurring after 2 years.

CONCLUSIONS

Conclusively, we believe that there is no necessity for enrolling all iAMP21 patients into the high-risk arm of ongoing ALL-BFM trials because MRD low-risk patients have a moderate relapse risk under current therapy. Whether the increased relapse risk in MRD intermediate-risk patients can be avoided by late treatment intensification remains to be answered by the AIEOP-BFM ALL 2009 trial randomly using protracted pegylated L-asparaginase during delayed intensification and early maintenance.

Targetable kinase-activating lesions in Ph-like acute lymphoblastic leukemia

BACKGROUND

Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL) is characterized by a gene-expression profile similar to that of BCR-ABL1-positive ALL, alterations of lymphoid transcription factor genes, and a poor outcome. The frequency and spectrum of genetic alterations in Ph-like ALL and its responsiveness to tyrosine kinase inhibition are undefined, especially in adolescents and adults.

METHODS

We performed genomic profiling of 1725 patients with precursor B-cell ALL and detailed genomic analysis of 154 patients with Ph-like ALL. We examined the functional effects of fusion proteins and the efficacy of tyrosine kinase inhibitors in mouse pre-B cells and xenografts of human Ph-like ALL.

RESULTS

Ph-like ALL increased in frequency from 10% among children with standard-risk ALL to 27% among young adults with ALL and was associated with a poor outcome. Kinase-activating alterations were identified in 91% of patients with Ph-like ALL; rearrangements involving ABL1, ABL2, CRLF2, CSF1R, EPOR, JAK2, NTRK3, PDGFRB, PTK2B, TSLP, or TYK2 and sequence mutations involving FLT3, IL7R, or SH2B3 were most common. Expression of ABL1, ABL2, CSF1R, JAK2, and PDGFRB fusions resulted in cytokine-independent proliferation and activation of phosphorylated STAT5. Cell lines and human leukemic cells expressing ABL1, ABL2, CSF1R, and PDGFRB fusions were sensitive in vitro to dasatinib, EPOR and JAK2 rearrangements were sensitive to ruxolitinib, and the ETV6-NTRK3 fusion was sensitive to crizotinib.

CONCLUSIONS

Ph-like ALL was found to be characterized by a range of genomic alterations that activate a limited number of signaling pathways, all of which may be amenable to inhibition with approved tyrosine kinase inhibitors. Trials identifying Ph-like ALL are needed to assess whether adding tyrosine kinase inhibitors to current therapy will improve the survival of patients with this type of leukemia. (Funded by the American Lebanese Syrian Associated Charities and others.).

Variation at 10p12.2 and 10p14 influences risk of childhood B-cell acute lymphoblastic leukemia and phenotype

Acute lymphoblastic leukemia (ALL) is the major pediatric cancer diagnosed in economically developed countries with B-cell precursor (BCP)-ALL, accounting for approximately 70% of ALL. Recent genome-wide association studies (GWAS) have provided the first unambiguous evidence for common inherited susceptibility to BCP-ALL, identifying susceptibility loci at 7p12.2, 9p21.3, 10q21.2, and 14q11.2. To identify additional BCP-ALL susceptibility loci, we conducted a GWAS and performed a meta-analysis with a published GWAS totaling 1658 cases and 4723 controls, with validation in 1449 cases and 1488 controls. Combined analysis identified novel loci mapping to 10p12.2 (rs10828317, odds ratio [OR] = 1.23; P = 2.30 × 10(-9)) and 10p14 marked by rs3824662 (OR = 1.31; P = 8.62 × 10(-12)). The single nucleotide polymorphism rs10828317 is responsible for the N215S polymorphism in exon 7 of PIP4K2A, and rs3824662 localizes to intron 3 of the transcription factor and putative tumor suppressor gene GATA3. The rs10828317 association was shown to be specifically associated with hyperdiploid ALL, whereas the rs3824662-associated risk was confined to nonhyperdiploid non-TEL-AML1 + ALL. The risk allele of rs3824662 was correlated with older age at diagnosis (P < .001) and significantly worse event-free survivorship (P < .0001). These findings provide further insights into the genetic and biological basis of inherited genetic susceptibility to BCP-ALL and the influence of constitutional genotype on disease development.

[The abnormal expression of IKZF1 encoded protein-IKAROS in B-ALL children]

OBJECTIVE

To analyze the isoforms of IKAROS in the bone marrow samples from children with acute B-lineage lymphoblastic leukemia (B-ALL) and to investigate the relationship between frequency of dominant-negative (DN) IKAROS isoforms and prognosis of B-ALL, and to preliminarily study the relevant mechanism.

METHODS

A total of 137 children with newly diagnosed B-ALL, who sequentially entered the Department of Hematology and Oncology, Shanghai Children's Medical Center between January 2005 and September 2010, were included in the study. Nest-PCR, Sanger sequencing, and TA cloning were used to analyze the expression of IKAROS isoforms in these children. The relationship between frequency of DN IKAROS isoforms and prognosis of B-ALL was investigated.

RESULTS

Of the 137 children with newly diagnosed B-ALL, 16 had expression of IK6, 14 had expression of IK4, and 2 had expression of IK7. There was significant difference in 2.5-year event-free survival between the cohorts of DN IKAROS and non-DN IKAROS (P=0.01). Analysis of the 10 paired of diagnosis/relapse samples from 10 patients with recurrence showed that 8 of 10 paired diagnosis and relapse samples had inconsistent expression of IKAROS isoforms. The rate of IK6 expression in relapse samples from 21 relapse ALL patients was significantly higher than in the 137 children with newly diagnosed ALL (62% vs 12%, P<0.01).

CONCLUSIONS

Expression of DN IKAROS isoforms can be a poor prognostic factor in B-ALL and is closely associated with recurrence of B-ALL.

Implication of IRF4 aberrant gene expression in the acute leukemias of childhood

The most frequent targets of genetic alterations in human leukemias are transcription factor genes with essential functions in normal blood cell development. The Interferon Regulatory Factor 4 (IRF4) gene encodes a transcription factor important for key developmental stages of hematopoiesis, with known oncogenic implications in multiple myeloma, adult leukemias and lymphomas. Very few studies have reported an association of IRF4 with childhood malignancy, whereas high transcript levels have been observed in the more mature immunophenotype of ALL. Our aim was to investigate the expression levels of IRF4 in the diagnostic samples of pediatric leukemias and compare them to those of healthy controls, in order to determine aberrant gene expression and whether it extends to leukemic subtypes other than the relatively mature ALL subpopulation. Quantitative real-time RT-PCR methodology was used to investigate IRF4 expression in 58 children with acute leukemias, 4 leukemic cell lines and 20 healthy children. We show that aberrant IRF4 gene expression is implicated in a variety of leukemic subtypes; higher transcript levels appear in the more immature B-common ALL subtype and in T-cell than in B-cell leukemias, with the highest expression levels appearing in the AML group. Interestingly, we show that childhood leukemia, irrespective of subtype or cell maturation stage, is characterised by a minimum of approximately twice the amount of IRF4 gene expression encountered in healthy children. A statistically significant correlation also appeared to exist between high IRF4 expression and relapse. Our results show that ectopic expression of IRF4 follows the reverse expression pattern of what is encountered in normal B-cell development and that there might be a dose-dependency of childhood leukemia for aberrantly expressed IRF4, a characteristic that could be explored therapeutically. It is also suggested that high IRF4 expression might be used as an additional prognostic marker of relapse at diagnosis.

Targeting JAK1/2 and mTOR in murine xenograft models of Ph-like acute lymphoblastic leukemia

CRLF2 rearrangements, JAK1/2 point mutations, and JAK2 fusion genes have been identified in Philadelphia chromosome (Ph)-like acute lymphoblastic leukemia (ALL), a recently described subtype of pediatric high-risk B-precursor ALL (B-ALL) which exhibits a gene expression profile similar to Ph-positive ALL and has a poor prognosis. Hyperactive JAK/STAT and PI3K/mammalian target of rapamycin (mTOR) signaling is common in this high-risk subset. We, therefore, investigated the efficacy of the JAK inhibitor ruxolitinib and the mTOR inhibitor rapamycin in xenograft models of 8 pediatric B-ALL cases with and without CRLF2 and JAK genomic lesions. Ruxolitinib treatment yielded significantly lower peripheral blast counts compared with vehicle (P < .05) in 6 of 8 human leukemia xenografts and lower splenic blast counts (P < .05) in 8 of 8 samples. Enhanced responses to ruxolitinib were observed in samples harboring JAK-activating lesions and higher levels of STAT5 phosphorylation. Rapamycin controlled leukemia burden in all 8 B-ALL samples. Survival analysis of 2 representative B-ALL xenografts demonstrated prolonged survival with rapamycin treatment compared with vehicle (P < .01). These data demonstrate preclinical in vivo efficacy of ruxolitinib and rapamycin in this high-risk B-ALL subtype, for which novel treatments are urgently needed, and highlight the therapeutic potential of targeted kinase inhibition in Ph-like ALL.

[Analysis of clinical features and prognostic significance of childhood T-lineage acute lymphoblastic leukemia]

This study was aimed to explore the clinical features and prognosis outcome of childhood T-cell acute lymphoblastic leukemia (T-ALL). The clinical data of 38 cases of newly diagnosed T-ALL from Jan 2005 to Aug 2010 were analyzed retrospectively, and 78 cases of B-ALL with intermediate and high risk were collected as control group, then the sensitive rate of patients to prednisone pretreatment, complete remission (CR) rate at day 33 after induction chemotherapy, relapse rate and 3-year event-free survival (EFS) were compared between T-ALL and B-ALL children. The results showed that no significant statistic difference were found in distribution of age, infiltration of liver, spleen and lymph nodes as well as central nervous system disease, chromosome abnormality, expression level of fusion gene and so on between T-ALL and B-ALL groups (p > 0.05), but there were significant differences in sex and number of cases with WBC count ≥ 50 × 10(9)/L between them (p < 0.05). The sensitive rate of T-ALL and B-ALL patients to prednisone pretreatment was 51.9% and 89.3% respectively (p < 0.05). The ratio failed to achieve CR at day 33 after induction chemotherapy was 15.4% and 8.1% in the two groups (p > 0.05). The relapse rate of T-ALL and B-ALL cases was 30.8% (8/26) and 14.9% (11/74) respectively (p > 0.05). The time from CR to relapse was (9.78 ± 3.48) month and (21.28 ± 14.32) month (p < 0.05). The 3 year EFS of T-ALL cases with intermediate and high risk was (37.5 ± 17.1)% and (22.2 ± 9.8)%, while 3 year EFS of B-ALL cases was (66.7 ± 7)% and (51.7 ± 9.3)% respectively (p < 0.05) according to Kaplan-Meier survival curve. It is concluded that as compared with B-ALL cases, the male ratio and initial WBC count are higher, moreover the early response to prednisone pretreatment and 3 year EFS are poor in T-ALL cases, the prognosis outcome is poor also.

[Prognostic significance of TEL/AML1 rearrangement and its additional genetic changes in Korean childhood precursor B-acute lymphoblastic leukemia]

BACKGROUND

TEL (ETV6)/AML1 (RUNX1) rearrangement is observed in approximately 20-25% of childhood precursor B-ALL and is associated with a favorable outcome. Additional genetic changes, associated with TEL/AML1, are frequently found. We evaluated the prevalence and prognostic significance of TEL/AML1 rearrangement and additional genetic changes in the TEL and AML1 genes in Korean childhood precursor B-ALL.

METHODS

We performed FISH using LSITEL/AML1 ES probe (Vysis, USA) in 123 children diagnosed as having precursor B-ALL and assessed clinical relevance of the TEL/AML1 rearrangement and additional genetic abnormalities.

RESULTS

The frequency of TEL/AML1 was 17.1% (21/123) in patients with precursor B-ALL. TEL/ AML1-positive group showed male predominance (P=0.012) and younger age of onset than TEL/ AML1-negative group by 1.6 yr (P=0.013). The outcome of TEL/AML1-positive group tended to show lower incidences of relapse (1/21 vs 20/102), death (1/21 vs 17/102) and longer event free survival. Among TEL/AML1-positive patients, unrearranged TEL deletion, AML1 gain, and unrearranged TEL deletion combined with AML1 gain were detected in 61.9%, 23.8%, and 9.5%, respectively. There were no significant differences in the clinical features and outcome according to the presence or absence of additional genetic changes.

CONCLUSIONS

The frequency of TEL/AML1 and additional genetic changes in TEL and AML1 is higher than previous studies in Korean children, and in close agreement with usually reported one, 20-25%. TEL/AML1-positive group showed a tendency toward better prognosis. Further study is needed to clarify the prognostic significance of additional changes in TEL and AML1 based on a large sample size.

Outcome of haematopoietic stem cell transplantation for paediatric acute lymphoblastic leukaemia in third complete remission: a vital role for graft-versus-host-disease/ graft-versus-leukaemia effect in survival

Children with acute lymphoblastic leukaemia (ALL) receiving haematopoietic stem cell transplantation (HSCT) in third complete remission (CR3) are at high risk for transplant-related mortality (TRM) and relapse. Twenty-two consecutive children with ALL in CR3 received HSCT between January 1994 and August 2005. Ten patients died of TRM, seven patients relapsed, six did not have graft-versus-host disease (GVHD). Five patients were long-term survivors, (median follow-up, 5.8 years; range 2.9-11.7). Three-year event-free survival was 0.32 (95% confidence interval 0.19 and 0.59). Survivors had moderate to severe GVHD. Allowing some GVHD or exploring means of inducing GVHD should be considered in CR3 patients.

Survivin and its prognostic significance in pediatric acute B-cell precursor lymphoblastic leukemia

BACKGROUND AND OBJECTIVES

Impaired apoptosis, mediated by members of the inhibitor of apoptosis proteins (IAP) family such as survivin, is thought to contribute to leukemic cell survival. In contrast to low expression of survivin in normal differentiated adult tissues, very high levels of survivin have been described in a number of different tumors. Overexpression of survivin was found to correlate with poor prognosis in a variety of cancers including hematologic malignancies. To date, however, there is no information available on the prognostic role of survivin in pediatric precursor B-cell acute lymphocytic leukemia (BCP-ALL), the most frequent malignancy in childhood.

DESIGN AND METHODS

In a retrospective study including 66 pediatric patients we analyzed the impact of survivin protein levels on outcome in BCP-ALL.

RESULTS

Survivin overexpression, with an up to ten-fold increase of the normal level, was detected in 65% of the leukemic samples in contrast to negligible expression in non-malignant hematopoietic cells. Despite considerable variety of expression levels in ALL cells, there was no association of survivin levels with established risk factors. However, patients suffering relapse of disease or death had significantly higher survivin expression than those with a favorable outcome. Overexpression of survivin is a significant prognostic marker for 3 year relapse free, event-free and overall survival, again independent of the established prognostic factors in ALL, such as age and leukocyte count at diagnosis as assessed in multivariate analysis.

INTERPRETATION AND CONCLUSIONS

Overexpression of survivin in BCP-ALL identifies patients with a high risk of early relapse. Upon confirmation in a prospective analysis, survivin expression may, in the future, serve to further refine treatment stratification with intensification of therapy in those patients prone to relapse.

Clearance of minimal residual disease after allogeneic stem cell transplantation and the prediction of the clinical outcome of adult patients with high-risk acute lymphoblastic leukemia

BACKGROUND AND OBJECTIVES

The molecular analysis of minimal residual disease (MRD) may provide information on the risk of recurrence in patients with acute lymphoblastic leukemia (ALL). The aim of this study was to correlate the kinetics of MRD clearance after allogeneic transplantation with the clinical outcome of adults with ALL.

DESIGN AND METHODS

MRD was evaluated by real-time quantitative polymerase chain reaction (RQ-PCR) using probes derived from fusion chimeric genes (BCR/ABL and MLL/AF4) (n=22) or rearrangements of the T-cell receptor or immunoglobulin genes (n=21). Forty-three adult patients with ALL were studied to correlate the kinetics of MRD clearance before and after allogeneic hematopoietic stem cell transplantation.

RESULTS

At 36 months, the overall survival of patients who underwent transplantation in hematologic remission (n= 37) was 80% for those who were PCR-negative before transplantation (n= 12) compared to 49% for PCR-positive patients (n= 25)(p=0.17). For the same patients the cumulative incidence of relapse was 0% and 46%, respectively (p=0.027). Moreover, the relapse rate of patients who were PCR-negative at day +100 after transplantation was remarkably low (7%) compared to that among patients who were PCR-positive (80%, p=0.0006).

INTERPRETATION AND CONCLUSIONS

The kinetics of MRD clearance may help to identify patients at high risk of leukemia relapse after allogeneic stem cell transplantation. Patients not achieving an early molecular remission after transplantation require prompt and appropriate pre-emptive treatments such as infusions of donor lymphocytes or new experimental drugs.

Prognostic significance of CD20 expression in childhood B-cell precursor acute lymphoblastic leukemia

CD20 expression is associated with inferior survival in adults with acute lymphoblastic leukemia (ALL). We analyzed the prognostic impact of CD20 expression in 353 children with B-cell precursor ALL treated in 3 consecutive St Jude Total Therapy studies. CD20 expression (> 20%) was found in 169 patients (48%) and was more frequent in patients between 1 and 10 years of age than in those younger than 1 or older than 10 years (P = .001). None of 14 patients with MLL-AF4 expressed CD20. There was no association between CD20 expression and E2A-PBX, TEL-AML1, ploidy, white blood cell count at diagnosis, or sex. In contrast to the experience in adult ALL, our patients with CD20 expression tended to have a better treatment outcome than those without the expression: 5-year event-free survival 84% +/- 2.9% versus 78% +/- 3.1% (P = .08). These data suggest that CD20 expression is not associated with inferior outcome in pediatric patients treated with contemporary regimens.

Risk- and response-based classification of childhood B-precursor acute lymphoblastic leukemia: a combined analysis of prognostic markers from the Pediatric Oncology Group (POG) and Children's Cancer Group (CCG)

The Children's Cancer Group (CCG) and the Pediatric Oncology Group (POG) joined to form the Children's Oncology Group (COG) in 2000. This merger allowed analysis of clinical, biologic, and early response data predictive of event-free survival (EFS) in acute lymphoblastic leukemia (ALL) to develop a new classification system and treatment algorithm. From 11 779 children (age, 1 to 21.99 years) with newly diagnosed B-precursor ALL consecutively enrolled by the CCG (December 1988 to August 1995, n=4986) and POG (January 1986 to November 1999, n=6793), we retrospectively analyzed 6238 patients (CCG, 1182; POG, 5056) with informative cytogenetic data. Four risk groups were defined as very high risk (VHR; 5-year EFS, 45% or below), lower risk (5-year EFS, at least 85%), and standard and high risk (those remaining in the respective National Cancer Institute [NCI] risk groups). VHR criteria included extreme hypodiploidy (fewer than 44 chromosomes), t(9;22) and/or BCR/ABL, and induction failure. Lower-risk patients were NCI standard risk with either t(12;21) (TEL/AML1) or simultaneous trisomies of chromosomes 4, 10, and 17. Even with treatment differences, there was high concordance between the CCG and POG analyses. The COG risk classification scheme is being used for division of B-precursor ALL into lower- (27%), standard- (32%), high- (37%), and very-high- (4%) risk groups based on age, white blood cell (WBC) count, cytogenetics, day-14 marrow response, and end induction minimal residual disease (MRD) by flow cytometry in COG trials.

The prognostic significance of CDKN2A, CDKN2B and MTAP inactivation in B-lineage acute lymphoblastic leukemia of childhood. Results of the EORTC studies 58881 and 58951

BACKGROUND AND OBJECTIVES

Deletion and methylation of the 9p21 chromosomal region are frequent in childhood acute lymphoblastic leukemia (ALL) but the prognostic significance is controversial. They inactivate CDKN2A, a gene encoding both p16INKa and p14ARF and, in some cases, contiguous genes that may influence chemosensitivity, such as CDKN2B encoding p15INKb or MTAP encoding methylthioadenosine phosphorylase.

DESIGN AND METHODS

CDKN2A inactivation by deletion or methylation was studied using gene dosage and methyl-specific polymerase chain reaction.

RESULTS

Bi-allelic and mono-allelic inactivation were found in, respectively, 38 (17%) and 31 (14%) of 227 children with B-lineage ALL enrolled in EORTC trials. Although CDKN2A inactivation was more often associated with poor prognostic features in B-lineage ALL, it failed to influence the outcome of the patients significantly. Bi-allelic CDKN2B and MTAP co-inactivation were found in 36 (16%) and 24 (11%) of patients, respectively, and did not influence the 6-year event-free survival rate either, even when the analysis was restricted to CDKN2A inactivated ALL.

INTERPRETATION AND CONCLUSIONS

In this study of 227 cases of childhood B-lineage ALL, inactivation of CDKN2A, CDKN2B and MTAP did not influences the patients' outcome.

Prospective analysis of TEL/AML1-positive patients treated on Dana-Farber Cancer Institute Consortium Protocol 95-01

In a retrospective analysis, we previously reported that children whose leukemia cells harbored the TEL/AML1 gene rearrangement have excellent outcomes. From 1996 to 2000, we conducted a prospective study to determine the incidence and outcomes of children with TEL/AML1-positive acute lymphoblastic leukemia (ALL). Children with newly diagnosed ALL were treated on DFCI ALL Consortium Protocol 95-01. Patients were risk stratified primarily by current National Cancer Institute (NCI)-Rome risk criteria. With a median follow-up of 5.2 years, the 5-year event-free survival for TEL/AML1-positive patients was 89% compared with 80% for TEL/AML1-negative B-precursor patients (P = .05). The 5-year overall survival rate was 97% among TEL/AML-positive patients compared with 89% among TEL/AML1-negative patients (P = .03). However, in a multivariable analysis, risk group (age and leukocyte count at diagnosis) and asparaginase treatment group, but not TEL/AML1 status, were found to be independent predictors of outcome. We conclude that TEL/AML1-positive patients have excellent outcomes, confirming our previous findings. However, factors such as age at diagnosis and presenting leukocyte count should be taken into consideration when treating this group of patients.

Genetic abnormalities associated with the t(12;21) and their impact in the outcome of 56 patients with B-precursor acute lymphoblastic leukemia

The ETV6/RUNX1 rearrangement is found in 20-30% of children with B-cell precursor acute lymphoblastic leukemia and is associated with a good outcome. To determine the cytogenetic and molecular abnormalities associated with the ETV6/RUNX1 rearrangement and the influence of this rearrangement in patients' evolution, we analyzed the molecular cytogenetic profiles of 56 children with this rearrangement and B-cell precursor acute lymphoblastic leukemia. Secondary changes detected with conventional cytogenetics and with fluorescence in situ hybridization were found in 71.4% of cases, the most frequent being the loss of the normal ETV6 allele, 12p aberrations, duplication of the fusion gene, and trisomy 21, as in replicating the results of previous studies. In this preliminary series, with a mean follow-up of 69.3 months, secondary abnormalities did not influence patients' outcome. It seems therefore that the prognostic value of the t(12;21) does not vary and that ETV6/RUNX1 rearrangement is an independent indicator of good prognosis.

Molecular detection of minimal residual disease is associated with early relapse in adult acute lymphoblastic leukemia

Several studies in childhood acute lymphoblastic leukemia (ALL) have documented that molecular detection of minimal residual disease (MRD) based on screening for T-cell receptor and immunoglobulin gene rearrangements can identify patients at a high risk of relapse. In our experience, evaluation of MRD in adult ALL can help to identify high risk patients.

High-dose daunorubicin as liposomal compound (Daunoxome) in elderly patients with acute lymphoblastic leukemia

Elderly acute lymphoblastic leukemia (ALL) is a rare condition associated with low complete remission (CR) rate and short survival. In order to improve these results, we evaluate the efficacy and toxicity of Daunoxome, a liposomal daunorubicin, exhibiting toxicity profile and pharmacokinetic indices better than standard daunorubicin. In total, 15 consecutive patients with nonmature ALL were enrolled on a prospective phase II study. No exclusion was made because of older age, poor performance status and organ dysfunctions. Median age was 69 years; performance status resulted >/=2 in nine patients (60%), six patients (40%) were bcr-abl positive and two-thirds of the patients had comorbidities. Induction therapy consisted of vincristine, Daunoxome and dexamethasone. Patients in CR received one or two consolidation cycles of cyclophosphamide, cytarabine and topotecan followed, in patients achieving CR, by a two-year rotating maintenance course including vincristine, Daunoxome, cyclophosphamide and prednisone. In all, 11 patients (73%) achieved CR, three patients (20%) died early during the induction phase and one patient (7%) had resistant disease. Five patients (33%) relapsed after 5-21 months. With a median follow-up of 20 months, disease free survival (DFS) and overall survival (OS) at 2 years were 36 and 38%, respectively. Major toxicity included myelosuppression and infection. Our experience demonstrates that a high dose of daunorubicin as liposomal compound can be safely administered in elderly ALL, exhibiting high antitumor activity. Our therapeutic program shows evidence of benefit in DFS and OS.

DNA microarrays for comparison of gene expression profiles between diagnosis and relapse in precursor-B acute lymphoblastic leukemia: choice of technique and purification influence the identification of potential diagnostic markers

Microarrays for gene expression profiling are rapidly becoming important research tools for the identification of novel markers, for example, for novel classification of leukemias and lymphomas. Here, we review the considerations and infrastructure for microarray experiments. These considerations are illustrated via a microarray-based comparison of gene expression profiles of paired diagnosis-relapse samples from patients with precursor-B acute lymphoblastic leukemia (ALL), who relapsed during therapy or after completion of treatment. Initial experiments showed that several seemingly differentially expressed genes were actually derived from contaminating non-leukemic cells, particularly myeloid cells and T-lymphocytes. Therefore, we purified the ALL cells of the diagnosis and relapse samples if their frequency was lower than 95%. Furthermore, we observed in earlier studies that extra RNA amplification leads to skewing of particular gene transcripts. Sufficient (non-amplified) RNA of purified and paired diagnosis-relapse samples was obtained from only seven cases. The gene expression profiles were evaluated with Affymetrix U95A chips containing 12 600 human genes. These diagnosis-relapse comparisons revealed only a small number of genes (n=6) that differed significantly in expression: mostly signaling molecules and transcription factors involved in cell proliferation and cell survival were highly upregulated at relapse, but we did not observe any increase in drug-resistance markers. This finding fits with the observation that tumors with a high proliferation index have a poor prognosis. The genes that changed between diagnosis and relapse are currently not in use as diagnostic or disease progression markers, but represent potential new markers for such applications. Leukemia (2003) 17, 1324-1332. doi:10.1038/sj.leu.2402974

Methotrexate polyglutamation may lack prognostic significance in children with B-cell precursor acute lymphoblastic leukemia treated with intensive oral methotrexate

BACKGROUND

The purpose of this study was to determine if a correlation exists between clinical outcome and accumulation and polyglutamation of methotrexate by lymphoblasts in vitro in children with B-cell precursor acute lymphoblastic leukemia (BCP-ALL).

PATIENTS AND METHODS

The amount of accumulated methotrexate and of long-chain methotrexate polyglutamates (MTXPG(3-7)) by lymphoblasts was determined in 52 children newly diagnosed with BCP-ALL after incubation with 1 micromol/L [(3)H]MTX for 24 hours in vitro. All patients then received intensive multiagent chemotherapy that used divided-dose oral methotrexate during consolidation and intensive continuation and standard oral weekly methotrexate during maintenance.

RESULTS

Eight patients had a bone marrow relapse at a median of 40.4 months (range 18.5-48.3 months) after diagnosis. The median follow-up for the remaining 44 patients is 69.0 months (range 22-92.8 months). There was no significant difference in the amount of accumulated methotrexate (1450.0 +/- 896.3 vs. 640 +/- 472.5 pmol/10 cells) or of accumulated MTXPG (1450.0 +/- 919.4 vs. 617.4 +/- 482.7 pmol/10(9) cells) (median +/- semi-interquartile ranges) between patients who relapsed and those who remained in continuous complete remission. The estimated 5-year event-free survival rate for patients whose lymphoblasts accumulated more than 500 pmol MTXPG(3-7)/10(9) cells was 80.0% +/- 7.3% versus 90.5% +/- 6.4% for those whose lymphoblasts accumulated less than 500 pmol MTXPG(3-7)/10(9) cells.

CONCLUSIONS

In the context of effective prolonged divided-dose oral methotrexate-based therapy in the treatment of BCP-ALL, methotrexate accumulation and polyglutamation no longer seem to have prognostic significance.

Loss of heterozygosity of p16 correlates with minimal residual disease at the end of the induction therapy in non-high risk childhood B-cell precursor acute lymphoblastic leukemia

We evaluated the incidence of MTS1/p16 deletions by loss of heterozygosity (LOH) analysis in 36 non-high risk B-cell precursor childhood acute lymphoblastic leukemia (BCP-ALL) and correlated these results with clinical features and with the presence of minimal residual disease (MRD) at the end of induction therapy. LOH was analyzed using three microsatellite markers flanking the p16 gene. MRD was studied by the polymerase chain reaction (PCR) for IgH and TCRdelta genes. All patients were classified and treated according to the BFM-86 protocol. A slower response to the induction treatment (MRD) was associated with LOH of p16 and worse clinical outcome. Thus, LOH of p16 may be a marker of chemotherapy resistance among the children classified as non-high risk BCP-ALL.

Role of early anthracycline dose-intensity according to expression of Philadelphia chromosome/BCR-ABL rearrangements in B-precursor adult acute lymphoblastic leukemia

INTRODUCTION

The use of anthracycline antibiotics in adult acute lymphoblastic leukemia (ALL) has resulted in an improved outcome to remission induction therapy. However,the exact role of these drugs in consolidation therapy is less clear, especially in specific ALL subsets.

MATERIALS AND METHODS

A retrospective analysis was conducted on the outcome of 308 patients (median age 35 years, range 13-75) with the most frequent subtype, early-B ALL, treated between 1974 and 1998 on eight consecutive protocols. Anthracycline-related effects were assessed by evaluating the impact of planned anthracycline dose-intensity (A-DI) on long-term outcome. A-DI (in mg/m(2)/week) during the first twelve weeks of consolidation therapy was classified as either "high" (doxorubicin>20, idarubicin>7) or "low".

RESULTS

Complete remission was achieved in 78% of cases. With a median follow-up of 6.5 years, on multivariate analysis, disease-free survival (DFS) correlated only with expression of the Philadelphia (Ph) chromosome and/or associated BCR-ABL rearrangements (Ph/BCR(+)) (P=0.0001) and planned A-DI (P<0.0001). On this basis, four major prognostic groups with significantly different DFS could be identified: (1) Ph/BCR(-), "high" A-DI (n=102), median 3.5 years and 41% at five years, respectively; (2) Ph/BCR(-), "low" A-DI (n=64), 1.3 years and 16%; (3) Ph/BCR(+), "high" A-DI (n=35), 1.7 years and 20%; (4) Ph/BCR(+), "low" A-DI (n=39), 0.75 years and 0%. When analyzed separately for Ph/BCR(-) (n=166) and Ph/BCR(+) (n=74) patients, the A-DI effect on DFS was preserved in the former (P=0.018) whereas, in Ph/BCR(+) patients, only age <50 years (P=0.004) and blast count <25 x 10(9)/l (P=0.02) correlated with better DFS. However, Ph/BCR(+) patients with the best prognostic profile (age <50 years and blast count <25 x 10(9)/l; n=21) who were treated on "high" A-DI regimens experienced a median DFS of 2.2 years with DFS 21% at five years, compared to 0.67-1 years and 0-10% in other cases (n=53, P<0.01).

CONCLUSION

A "high" A-DI may act as a positive treatment-related prognostic factor in early B-lineage ALL. Although mainly restricted to patients with Ph/BCR(-) ALL, A-DI could also influence the outcome in Ph/BCR(+) patients with other favorable prognostic factors.

Leading prognostic relevance of the BCR-ABL translocation in adult acute B-lineage lymphoblastic leukemia: a prospective study of the German Multicenter Trial Group and confirmed polymerase chain reaction analysis

The BCR-ABL fusion, the molecular equivalent of the Philadelphia translocation, gains importance for treatment stratification in adult acute lymphoblastic leukemia (ALL). In this prospective study, samples from 478 patients with CD10(+) B-cell precursor ALL (c-ALL and pre-B ALL) underwent BCR-ABL reverse transcription-polymerase chain reaction (RT-PCR) analysis with double testing of positive samples. Patients were stratified according to the PCR result and treated in 2 German Multicenter Trials of Adult ALL. The outcome was followed and the prognostic impact of BCR-ABL was compared to clinical risk features. Of the 478 samples, 432 had an evaluable BCR-ABL result. Thirty-seven percent of the c-ALL and pre-B ALL patients were BCR-ABL(+) (p190, 77%; p210, 20%; simultaneous p190/p210, 3%). BCR-ABL positivity was associated with the high-risk features of older age (45 years versus 30 years median age; P =.0001) and higher white blood cell counts (23 500/microL versus 11 550/microL; P =.0001). Univariate and multivariate analyses revealed BCR-ABL as the leading factor for a poor prognosis (P =.0001) in comparison to clinical risk criteria. Irrespective of the breakpoint, presence of any BCR-ABL transcript predicted a lower chance of initial treatment response (68.4% versus 84.6%; P =.001) and a lower probability of disease-free survival at 3 years (0.13 versus 0.47; P =.0001). This bad outcome was not influenced by postinduction high-dose treatment stratifications. The results show a high prevalence of BCR-ABL fusion transcripts with predominance of p190. BCR-ABL RT-PCR is confirmed as a sensitive, rapid method to diagnose t(9;22), and p190 and p210 are unequivocally demonstrated as the most important predictors of poor long-term survival despite intensified chemotherapy.

Cytogenetic and FISH studies of a single center consecutive series of 152 childhood acute lymphoblastic leukemias

Between 1977 and 1996, cytogenetic investigations were performed on 182 childhood (< or = 16 yr) acute lymphoblastic leukemias (ALL), constituting 94% (182 of 194) of all ALL patients diagnosed and treated at the Departments of Pediatrics, Lund and Malmo University Hospitals, Sweden, during these two decades. The cytogenetic analyses were successful in 152 cases (84%). The failure rate was higher for the ALL investigated before 1987 (30% vs. 4%, p < 0.0001), and also the incidence of cytogenetically normal cases was higher during 1977-86 (43% vs. 25%, p < 0.05). Clonal chromosomal abnormalities were found in 103 (68%) ALL. Structural rearrangements were detected, by chromosome banding alone, in 76 cases (50%). Fluorescence in situ hybridization (FISH) was used to identify cases with t(12;21), 11q23 rearrangements, and 9p deletions, using probes for ETV6/CBFA2, MLL, and CDKN2A/B, in 72 cases from which cells in fixative and/or unstained metaphase preparations were available. In total, the most common structural rearrangements were del(9p) (17%), t(12;21) (15%), del(6q) (8%), and MLL rearrangements (4%). Six (32%) of nineteen cytogenetically normal ALL analyzed by FISH harbored cryptic abnormalities; three displayed t(12;21) and four had del(9p), one of which also carried a t(12;21). Five (45%) of the t(12;21)-positive ALL showed +der(21)t(12;21) or ider(21)(q10)t(12;21), resulting in the formation of double fusion genes. Among the more rare aberrations, eight structural rearrangements were identified as novel recurrent ALL-associated abnormalities, and nine cases harbored rearrangements previously not reported. Sixteen cases displayed karyotypically unrelated clones at different investigations. Seven ALL (5%) showed simple chromosomal changes, unrelated to the aberrations detected at diagnosis, during morphologic and clinical remission, and in all but one instance the patients remained in remission, with the abnormal clone disappearing in subsequent investigations. This indicates that the emergence of novel clonal chromosomal aberrations during remission in childhood ALL is rather common and does not by necessity predict a forthcoming relapse.

Detection of residual disease in pediatric B-cell precursor acute lymphoblastic leukemia by comparative phenotype mapping: method and significance

The present review summarizes our efforts in developing a novel immunologic approach ("Comparative Phenotype Mapping") targeted at assessing minimal residual disease (MRD) in B-cell precursor (BCP) acute lymphoblastic leukemia (ALL) patients. The method relies on quantitatively aberrant, leukemia-associated antigen expression patterns which allow to discriminate leukemic from normal BCP using a limited panel of antibody combinations and multidimensional flow cytometry. In an analysis of 63 follow up bone marrow samples of patients with BCP-ALL we show that this approach enables to efficiently detect MRD. Further clinical observation revealed that the patients which were MRD-positive by flow cytometry (although in morphological remission) had a very high probability of early disease recurrence compared to the good chances of a relapse-free survival (RFS) in the MRD-negative cohort (RFS 0.0 vs. 0.76 at 3 years). Comparative Phenotype Mapping thus proves to be a reliable method for MRD detection in BCP-ALL. Concluding remarks relate to the optional applications of the method as well as to future perspectives. An ongoing large prospective study which we are now conducting on the basis of Comparative Phenotype Mapping will clarify the clinical significance of MRD detection in ALL patients by this method, and will determine its value compared to related as well as molecular-genetic techniques.

Racial differences in the survival of childhood B-precursor acute lymphoblastic leukemia: a Pediatric Oncology Group Study

PURPOSE

We conducted a historic cohort study to test the hypothesis that, after adjustment for biologic factors, African-American (AA) children and Spanish surname (SS) children with newly diagnosed B-precursor acute lymphoblastic leukemia had lower survival than did comparable white children.

PATIENTS AND METHODS

From 1981 to 1994, 4,061 white, 518 AA, and 507 SS children aged 1 to 20 years were treated on three successive Pediatric Oncology Group multicenter randomized clinical trials.

RESULTS

AA and SS patients were more likely to have adverse prognostic features at diagnosis and lower survival than were white patients. The 5-year cumulative survival rates were (probability +/- SE) 81.9% +/- 0.6%, 68.6% +/- 2.1%, and 74.9% +/- 2.0% for white, AA, and SS children, respectively. Adjusting for age, leukocyte count, sex, era of treatment, and leukemia blast cell ploidy, we found that AA children had a 42% excess mortality rate compared with white children (proportional hazards ratio [PHR] = 1.42; 95% confidence interval [CI], 1.12 to 1. 80), and SS children had a 33% excess mortality rate compared with white children (PHR = 1.33; 95% CI, 1.19 to 1.49).

CONCLUSION

Clinical presentation, tumor biology, and deviations from prescribed therapy did not explain the differences in survival and event-free survival that we observed, although differences seem to be diminishing over time with improvements in therapy. The disparity in outcome for AA and SS children is most likely related to variations in chemotherapeutic response to therapy and not to compliance. Further improvements in outcome may require individualized dosing based on specific pharmacogenetic profiles, especially for AA and SS children.

Heterogeneous TCR delta Vdelta2-Ddelta3 rearrangements and their relation to IgH and TCR gamma gene status in childhood B cell precursor leukaemias

In this study we aimed to test the hypothesis that leukaemias with oligoclonal Vdelta2-Ddelta3 rearrangements are clonal at the IgH and TCRG gene status and that the oligoclonality is a poor prognostic marker. In ten leukaemias the individual Vdelta2-Ddelta3 rearrangements characterised different populations as deduced from single cell analysis and/or from densitometric differences of PCR products. Five of these leukaemias were clonal by the IgH and/or TCRG gene status. We therefore conclude that ALL is a clonal disease despite the presence of heterogeneous TCRD rearrangements. Our clinical data show that oligoclonality at the TCRD level does not represent an adverse prognostic factor.

Survival of childhood acute lymphoblastic leukemia: experience in Chennai

The object of this study was to evaluate the treatment outcome in children with acute lymphoblastic leukemia (ALL) in Chennai. The problems inherent in a developing country which affect outcome are analyzed. The importance of prognostic factors especially immunotyping is assessed. The period of study was from June 1991 to December 1995. A total of 135 children were studied. Pre B CALLA positive (CD10, CD19, HLA, DR) was the dominant immunotype in 75 children (69 per cent). T-cell ALL was seen in 15 (14 per cent), biphenotype in three (2 per cent), and B in one (0.9 per cent). Seventy children (53 per cent) were treated with a high risk protocol, 25 (17 per cent) received an intermediate risk, and 40 patients (30 per cent) received a standard risk protocol. Analyzing the outcome in 135 children, 34 (27 per cent) had event free survival (EFS) at the time of analysis; of these 41 per cent had EFS after 2 years of therapy, 31 per cent after 3 years and 18.7 per cent after 4 years (i.e. 1 year after stopping 3 years of therapy). Fifty-seven children (41 per cent) dropped out; 25 (18 per cent) died due to sepsis. Treatment obstacles included delay in diagnosis, poor health education and facilities, poor supportive care, and socio-economic problems.