Treatment of primary refractory or relapsed acute lymphoblastic leukemia (ALL) in children

Mechanisms and insights into drug resistance in cancer

Cancer drug resistance continues to be a major impediment in medical oncology. Clinically, resistance can arise prior to or as a result of cancer therapy. In this review, we discuss different mechanisms adapted by cancerous cells to resist treatment, including alteration in drug transport and metabolism, mutation and amplification of drug targets, as well as genetic rewiring which can lead to impaired apoptosis. Tumor heterogeneity may also contribute to resistance, where small subpopulations of cells may acquire or stochastically already possess some of the features enabling them to emerge under selective drug pressure. Making the problem even more challenging, some of these resistance pathways lead to multidrug resistance, generating an even more difficult clinical problem to overcome. We provide examples of these mechanisms and some insights into how understanding these processes can influence the next generation of cancer therapies.

Early relapse after rituximab chemoimmunotherapy

In relapsed/refractory childhood acute lymphoblastic leukemia (ALL) of the B-cell lineage rituximab, a monoclonal anti-CD20 antibody was used successfully in some cases. We report on a 15-year-old female with relapsed CD20-positive B-cell progenitor ALL treated with rituximab because of positive minimal residual disease signals after chemotherapy, as checked by flow cytometry and real time quantitative-PCR. Rituximab eliminated the CD20-positive subpopulation, but not the more immature leukemic cells. The patient died with fulminant aspergillosis before hematopoietic stem cell transplantation could be performed.

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.

A single high dose of idarubicin combined with high-dose ARA-C for treatment of first relapse in childhood 'high-risk' acute lymphoblastic leukaemia: a study of the AIEOP group

The outcome of children with acute lymphoblastic leukaemia (ALL) and early relapse remains unsatisfactory. In January 1995, the AIEOP (Associazione Italiana di Oncologia ed Ematologia Pediatrica) group opened a trial for children with ALL in first isolated or combined bone marrow relapse defined at high risk according to the length of first remission and the immunophenotype. The treatment plan included the combination of a single high-dose idarubicin and high-dose cytarabine as induction therapy followed by an intensive consolidation and stem cell transplant (SCT). In total, 100 children from 16 Italian centres were enrolled; 80 out of the 99 evaluable patients (81%) achieved second complete remission; eight (8%) died during induction and 11 (11%) failed to respond. A total of 42 out of the 80 responders (52.5%) received a SCT: 19 from an identical sibling, 11 from a matched unrelated donor and 12 from umbilical cord blood cells. The estimated 4-year overall survival and event-free survival were 25% and 21% respectively. Disease-free survival at 4 years was 25.8% for the 80 responders. At 4 years, 39 out of 100 children remain alive, with 27 of them free of leukaemia. This induction therapy has shown antileukaemic efficacy with acceptable toxicity; moreover, all responders proved eligible for intensive consolidation.

Combination therapy with methotrexate, vincristine, polyethylene-glycol conjugated-asparaginase, and prednisone in the treatment of patients with refractory or recurrent acute lymphoblastic leukemia

BACKGROUND

L-asparaginase in combination with methotrexate has synergistic antileukemic activity in a schedule-dependent fashion. A new preparation of L-asparaginase, polyethylene-glycol conjugated (PEG)-asparaginase, is a pharmacologically different formulation of L-asparaginase with distinct properties including a longer half-life and less immunogenic properties.

METHODS

Patients with refractory or recurrent acute lymphoblastic leukemia (ALL) were treated with a combination of methotrexate (MTX), vincristine, PEG-asparaginase, and prednisone (MOAP). The treatment was comprised of MTX, 100 mg/m(2) intravenously (i.v.), over 15 minutes on Days 1 and 14; PEG-asparaginase, 2500 IU/m(2), with a maximum dose of 3750 IU i.v. approximately 4-6 hours after MTX on Days 1 and 14; vincristine, 1.4 mg/m(2) (maximum dose, 2 mg) i.v., over 15 minutes on Days 1, 7, and 14; and prednisone, 200 mg daily orally, on Days 1-5 and 14-19.

RESULTS

Thirty-two patients with a median age of 34 years (range, 20-74 years) were treated. Eight patients (25%) had ALL that was refractory to prior therapy and 24 patients (75%) had recurrent disease. Seven patients (22%) achieved a complete remission (CR). Five patients (16%) died early due to infections. Features associated with a poor response were high pretreatment lactate dehydrogenase levels and Philadelphia chromosome positive disease. The median duration of CR was 16 weeks and the overall median survival after MOAP therapy was 12 weeks. Anaphylactic reactions were not observed during MOAP combination therapy.

CONCLUSIONS

MOAP is an active regimen in patients with refractory or recurrent ALL. This regimen is well tolerated and is not associated with allergic reactions. However, further studies regarding the pharmacologic interaction of MTX with PEG-asparaginase are needed to optimize this regimen.

High-dose cytarabine-containing chemotherapy with or without granulocyte colony-stimulating factor for children with acute leukemia

We sought to determine the role of granulocyte colony-stimulating factor (G-CSF) as an adjunct therapy in high-dose cytarabine-containing chemotherapy (HD C/T) for children with acute leukemia. Seventeen patients, aged 9 months to 18 years old, 8 ALL and 9 AML, were treated with cytarabine (Ara-C) 1 g/m2 q12h for 8 doses with mitoxantrone, idarubicin, VP-16, or asparaginase. A total of 71 courses of HD C/T was given. G-CSF was not used in 14 courses (Group A). Prophylactic G-CSF was given in 57 courses (Group B) as 200 microg/m2/d SC started one day after the completion of HD C/T and continued until the neutrophil recovery was maintained. The incidences of sepsis per course in Group A and Group B were 35.7% (5/14) and 40.4% (23/57), respectively. While 2 patients in Group A died of sepsis or pneumonia, none in Group B died. The mortality and delay in chemotherapy were fewer in Group B (P = 0.037 and 0.0006, respectively, Fisher exact test). There was a shorter average number of days of neutrophil <500/cumm, antibiotic usage, fever, and hospital stay in Group B (11, 8, 5, 17 days in Group B vs. 21, 17, 10, 37 days in Group A; P = 0.0001, log-rank test; 0.0006, 0.0023, 0.0001, Wilcoxon rank sum test, respectively). The incidence of neutropenic fever was lower in Group B, but the difference did not reach statistical significance (P = 0.06, Fisher exact test). We conclude that G-CSF as an adjunct therapy in HD C/T is effective in reducing mortality, days of neutropenia, antibiotic usage, fever, hospital stay, and frequency of delay in chemotherapy. The efficacy of this treatment approach requires further testing in a randomized, controlled trial.

Acute toxicity and effectiveness of idarubicin in childhood acute lymphoblastic leukemia

Anthracyclines have become important components of multi-agent remission induction and continuation therapy of acute lymphoblastic leukemia (ALL). New anthracycline derivatives are being investigated in an attempt to shift the balance of side effects and antileukemic potency. To evaluate the toxicity and efficacy of idarubicin (IDA) in childhood ALL, a prospective multicenter phase-II study was performed. A total of 51 children with prognostically poor recurrences of ALL were enrolled, all of whom had been exposed to anthracyclines during front-line treatment. A single 48-h continuous infusion of IDA at 24 mg/m2 was started on the first day of salvage treatment without concomitant systemic cytostatic agents. The response was assessed by reduction of leukemic blasts in the bone marrow and other compartments 2 wk later. IDA monotherapy caused complete and partial remissions in 5 and 20 patients, respectively (49%). Delays of treatment with subsequent polychemotherapy courses were frequent and mainly caused by prolonged intervals of myelosuppression and high rates of systemic infection. Non-hematological toxicities including acute cardiac reactions were transient and moderate. Our findings suggest that IDA is an effective drug for remission induction in children with ALL, with acute hematological toxicity being dose-limiting.