Recent advances in the management of acute lymphocytic leukemia

Outcome of children with high-risk acute lymphoblastic leukemia (HR-ALL): Nordic results on an intensive regimen with restricted central nervous system irradiation

BACKGROUND

Improvement in outcome of childhood high-risk (HR) ALL was sought with a very intensive Nordic protocol leaving most patients without CNS-RT.

METHODS

A total of 426 consecutive children entered the NOPHO-92 HR-ALL program. HR criteria included WBC > or =50 x 10(9)/L, CNS or testicular involvement, T-cell, lymphomatous features, t(9;22), t(4;11), or slow response. Of these, 152 children had very high risk (VHR) with special definitions. CNS consolidation was based on high-dose MTX (8 g/m2) and ARA-C (12 g/m2) alternating. VHR patients also received cranial RT.

RESULTS

The 9-year EFS was 61 +/- 3%, OS 74 +/- 2%, and EFS for T-ALL 62 +/- 4%. Cumulative incidence of isolated CNS relapse was 4.7 +/- 1%, and CNS relapse in total 9.9 +/- 2%. Poor prognostic factors were WBC > or =200 x 10(9)/L and a very slow response.

CONCLUSIONS

HR-ALL was successfully treated on the NOPHO-92 regimen, with a relatively low CNS relapse rate for non-irradiated children. WBC > or =200 x 10(9)/L and very slow response emerged as strong poor prognostic factors.

Improving outcome through two decades in childhood ALL in the Nordic countries: the impact of high-dose methotrexate in the reduction of CNS irradiation. Nordic Society of Pediatric Haematology and Oncology (NOPHO)

In this population-based material from the five Nordic countries (Denmark, Finland, Iceland, Norway and Sweden), 2860 children below 15 years of age were diagnosed with acute lymphoblastic leukemia (ALL) from July 1981 to June 1998. The annual incidence was 3.9/100,000 children and was stable throughout the study period. The development from regional or national protocols to common Nordic treatment protocols for all risk groups was completed in 1992 through a successive intensification with multidrug chemotherapy, including pulses of methotrexate in high doses and avoidance of cranial irradiation in most children. The overall event-free survival (EFS) at 5 years has increased from 56.5 +/- 1.7% in the early 1980s to 77.6 +/- 1.4% during the 1990s. The main improvements were seen in children with non-high risk leukemia. In high-risk patients, progress has been moderate, especially in children with high WBC (> or =100 x 10(9)/l) at diagnosis. During the last time period (January 1992-June 1998), only 10% of the patients have received cranial irradiation in first remission, while 90% of the patients have received pulses of high dose methotrexate (5-8 g/m2) isolated or combined with high-dose cytosine arabinoside (total dose 12 g/m2) plus multiple intrathecal injections of methotrexate as CNS-targeted treatment, not translating into increased cumulative incidence of CNS relapse.

On the prognostic value of systemic methotrexate clearance in childhood acute lymphocytic leukemia

The prognostic value of systemic methotrexate clearance (ClMTX) during high-dose therapy was evaluated in a cohort of 42 children with acute lymphocytic leukemia (ALL). As part of an extensive chemotherapy protocol, they had received a total of 293 methotrexate (MTX) infusions in the 6-8 g/m2 dose range. At the termination of the study, when they had all been followed up for 3.5 years or more, 26 of these patients were still in continuous complete remission, whereas 16 had suffered relapse. The intrapatient variability in ClMTX during the eight courses was up to six-fold. In 67% of the patients, the maximum level of ClMTX reached at least twice the minimum value. The coefficients of variation for the intra- and interindividual variability in ClMTX were 9-57% and 26-41%, respectively. The cumulative probability of relapse, estimated by the Kaplan-Meier procedure, was increased for patients with a high ClMTX during the initial treatment course, but the difference was not significant on a 5% level. There was no significant relationship between high individual median ClMTX and subsequent relapse of ALL. However, ClMTX during the initial infusion, the time-dependent mean for ClMTX, and the individual patient's median ClMTX, were significant predictors for event-free survival in a Cox proportional hazards regression analysis. The present study demonstrates gross pharmacokinetic variability and unpredictable values of ClMTX in subsequent courses after standardized administration of MTX to paediatric patients with ALL. In spite of the association between ClMTX and prognosis shown by some of the analyses, estimates of ClMTX rates may not necessarily be related to disease outcome in a way that can be exploited to the benefit of the individual patient.

Magnetic resonance imaging and neurological evaluation after treatment with high-dose methotrexate for acute lymphocytic leukaemia in young children

This study evaluates the occurrence of permanent cerebral white matter changes and neurological abnormalities in children treated at a young age for acute lymphocytic leukaemia. Our pilot treatment protocol did not include central nervous system irradiation, but intrathecal methotrexate and high-dose methotrexate infusions followed by very intensive folinic acid rescue. We examined 12 children in complete remission and off therapy 18 months to 9.5 years after their last methotrexate infusion. They were below 5 years of age at diagnosis and therefore expected to be at special risk of neurotoxic sequelae. Cerebral magnetic resonance imaging in the 11 cases thus evaluated did not reveal white matter abnormalities or other signal changes as signs of permanent treatment-related sequelae. We did not observe any pathological clinical neurological findings likely due to methotrexate.

Analysis of 6-mercaptopurine, 6-thioguanine nucleotides, and 6-thiouric acid in biological fluids by high-performance liquid chromatography

We present a rapid, sensitive and specific high-performance liquid chromatographic method for the analysis of 6-mercaptopurine (6MP), 6-thioguanine nucleotides (6TGN) and 6-thiouric acid (6TU), with excellent chromatographic separation of the thiopurines. Thiopurines in plasma and erythrocytes were extracted by mercuricellulose and re-eluted with beta-mercaptoethanol. For quantitative detection a reverse phase column (Lichrosorb RP-18 4 mm X 30 cm) and a UV detector were used. Detection limits were 20 nmol/l for 6MP in plasma, 250 nmol/l for 6TGN in erythrocytes, and 10 nmol/l and 15 nmol/l, respectively, for 6MP and 6TU in urine diluted 1:100 with beta-mercaptoethanol. Within-run and between-run variations were less than 10%. Recovery of 6MP added to plasma, and 6TGN monophosphate added to haemolysed erythrocytes were 91% and 81%, respectively.

BK virus infection in children with cancer: serological response studied by haemagglutination inhibition, neutralization, and IgG- and IgM-class specific ELISA tests

We recently developed enzyme-linked immunosorbent assays (ELISAs) for the detection of anti-BK virus IgG- and IgM-antibodies, and also a convenient and rapid serum neutralization test. Complemented by a traditional haemagglutination inhibition test (HAI) these methods were used to investigate the longitudinal response to BKV infection in sequentially taken sera from 29 children under treatment for cancer. In separate experiments it was shown that the results were not at any extent influenced by antibodies against other polyomaviruses. At the time of diagnosis the prevalence of specific IgG- and IgM-antibodies and the geometric mean IgG levels were not significantly different for the patients compared with a group of healthy children. The primary infections seemed to occur at the same age for the two groups of children. Seven of the patients had a primary infection with BKV. The results indicate that the host response in moderately immunosuppressed children during primary infection is the same as expected for healthy individuals with the development of specific IgG, HAI, and NT antibodies, and, usually, production of BKV-IgM for several months. The results indicated that whether specific IgM was demonstrated in the first sample or appeared later during a reactivation episode, this parameter was correlated with profound immunosuppression. Significant titre changes, detectable IgM antibodies and/or seroconversions were demonstrated in 69% (20/29) of the cancer patients. Such indications of recent viral activity was recorded in 42% (8/19) of children with meningococcal infections. The observation periods for the two groups of patients are, however, not directly comparable.

White cell count during maintenance chemotherapy for standard-risk childhood acute lymphoblastic leukemia: relation to relapse rate

In a retrospective study of 84 children with standard-risk acute lymphoblastic leukemia diagnosed in 1981-1986, mean white cell count (mWBC) during maintenance chemotherapy (MT) was found to be significantly related to risk of hematological relapse, giving patients with the higher mWBC the poorer outcome. The only other significant relapse-related risk factor was white-cell count at diagnosis. mWBC was not significantly related to white cell count at diagnosis, sex, age, or dose of methotrexate or mercaptopurine. Patients with low mWBC also had relatively low white-cell counts after cessation of therapy when compared with patients with high mWBC.

Thyroid function in children after cytostatic treatment for acute leukemia

Sixty-one children were examined for thyroid dysfunction as an adverse late effect after cessation of antileukemic treatment. The aim of the study was to contribute to clarifying which types of therapy can cause this endocrine disorder. Our treatment protocols do not include cranial irradiation as CNS prophylaxis, but we give relatively intensive intrathecal methotrexate treatment. The results indicate that this cytostatic regimen alone does not cause thyroid dysfunction as an adverse late effect.

Effects of local irradiation and i.v. methotrexate on brain morphology in rabbits: early changes

Brain damage following cranial radiation therapy can be crippling or even life-threatening and has been studied in both patients and animals. An additional toxic effect of chemotherapy has been found in children, who died following brain irradiation and systemic chemotherapy for the treatment of acute lymphoblastic leukemia. To study the interaction of radiation and drugs on brain tissue, we treated rabbits with brain irradiation and/or i.v. methotrexate. For a period of up to 3 months following radiation therapy, brain morphology was compared in seven treatment groups. Weekly doses of methotrexate administered i.v. produced no brain damage. Histological examination showed myelin swelling and beading 14 weeks after fractionated brain irradiation with 24 Gy. Combination of brain irradiation and methotrexate produced additional hypertrophy of microglia and pyknosis of adventitial cells. In none of these groups, even after doses of 48 Gy brain irradiation, was calcification or brain necrosis observed during the first 14 weeks following irradiation.