De novo purine synthesis inhibition and antileukemic effects of mercaptopurine alone or in combination with methotrexate in vivo

Methotrexate (MTX) and mercaptopurine (MP) are widely used antileukemic agents that inhibit de novo purine synthesis (DNPS) as a mechanism of their antileukemic effects. To elucidate pharmacodynamic differences among children with acute lymphoblastic leukemia (ALL), DNPS was measured in leukemic blasts from newly diagnosed patients before and after therapy with these agents. Patients were randomized to receive low-dose MTX (LDMTX: 6 oral doses of 30 mg/m(2)) or high-dose MTX (HDMTX: intravenous 1 g/m(2)) followed by intravenous MP; or intravenous MP alone (1 g/m(2)), as initial therapy. At diagnosis, the rate of DNPS in bone marrow leukemia cells was 3-fold higher in patients with T-lineage ALL compared with those with B-lineage ALL (769 +/- 189 vs 250 +/- 38 fmol/nmol/h; P =.001). DNPS was not consistently inhibited following MP alone but was markedly inhibited following MTX plus MP (median decrease 3% vs 94%; P <.001). LDMTX plus MP and HDMTX plus MP produced greater antileukemic effects (percentage decrease in circulating leukocyte counts) compared with MP alone (-50% +/- 4%, -56% +/- 3%, and - 20% +/- 4%, respectively; P <.0001). Full DNPS inhibition was associated with greater antileukemic effects compared with partial or no inhibition (-63% +/- 4% vs -37% +/- 4%; P <.0001) in patients with nonhyperdiploid B-lineage and T-lineage ALL. HDMTX plus MP yielded 2-fold higher MTX polyglutamate concentrations than LDMTX plus MP (2148 +/- 298 vs 1075 +/- 114 pmol/10(9) cells; P <.01) and a higher percentage of patients with full DNPS inhibition (78% vs 53%; P <.001). Thus, the extent of DNPS inhibition was related to in vivo antileukemic effects, and a single dose of intravenous MP produced minimal DNPS inhibition and antileukemic effects, whereas MTX plus MP produced greater antileukemic effects and DNPS inhibition, with full inhibition more frequent after HDMTX.

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

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

Bone mineral decrements in survivors of childhood acute lymphoblastic leukemia: frequency of occurrence and risk factors for their development

We assessed the clinical and treatment factors that predispose survivors of childhood acute lymphoblastic leukemia (ALL) to low bone mineral density (BMD). Using quantitative computed tomography, we determined the frequency of low BMD (defined as >1.645 standard deviations (SD) below the mean) in leukemia survivors treated with multiagent chemotherapy including prednisone and antimetabolite. All participants had completed therapy at least 4 years earlier, remained in continuous complete remission, and had no second malignancies. We statistically correlated BMD results with patient characteristics and treatment histories. Among 141 survivors (median age, 15.9 years; median time after diagnosis, 11.5 years), median BMD z score was -0.78 SD (range, -3.23 to 3.61 SDs). Thirty participants (21%; 95% confidence interval, 15% to 29%) had abnormally low BMD, a proportion significantly (P < 0.0001) greater than the expected 5% in normal populations. Risk factors for BMD decrements included male sex (P = 0.038), Caucasian race (P < 0.0001), and cranial irradiation (P= 0.0087). BMD inversely correlated with cranial irradiation dose. BMD z scores of patients who received higher doses of antimetabolites were lower than those of other patients. Childhood ALL survivors are at risk to have low BMD, especially males, Caucasians, and those who received cranial irradiation.

Long-term results of Total Therapy studies 11, 12 and 13A for childhood acute lymphoblastic leukemia at St Jude Children's Research Hospital

We present the long-term results of three consecutive clinical trials (Total Therapy studies 11, 12 and 13A) conducted for children with newly diagnosed acute lymphoblastic leukemia (ALL) between 1984 and 1994. In study 11 (1984-1988), the overall event-free survival rates (+/-1 s.e.) were 71.8 +/- 2.4% and 69.3 +/- 2.4%, and the cumulative risks of isolated central nervous system (CNS) relapse 5.6 +/- 1.2% and 5.9 +/- 1.3%, at 5 and 10 years, respectively. In study 12 (1988-1991), event-free survival rates were 67.6 +/- 3.4% and 61.5+/- 9.0%, and isolated CNS relapse rates were 10.4 +/- 2.3% and 10.4 +/- 2.3%, respectively. Early intensive intrathecal therapy in study 13A (1991-1994) has yielded a very low 5-year isolated CNS relapse rate of 1.2 +/- 0.9%, boosting the 5-year event-free survival rate to 76.9 +/- 3.3%. Factors consistently associated with an adverse prognosis included male sex, infant or adolescent age group, leukocyte count >100 x 10(9)/l, nonhyperdiploidy karyotype and poor early response to treatment. Risk classification based on age and leukocyte count had prognostic significance in B-lineage but not T-lineage ALL. Early therapeutic interventions or modifications for patients with specific genetic abnormalities or persistent minimal residual leukemia may further improve long-term results.

Traumatic lumbar puncture at diagnosis adversely affects outcome in childhood acute lymphoblastic leukemia

The effect of traumatic lumbar puncture at the time of initial diagnostic workup on treatment outcome in children with newly diagnosed acute lymphoblastic leukemia (ALL) was investigated. The findings of the first 2 lumbar punctures performed on 546 patients with newly diagnosed ALL treated on 2 consecutive front-line studies (1984-1991) at St Jude Children's Research Hospital were retrospectively reviewed. Lumbar punctures were performed at the time of diagnosis and again for the instillation of first intrathecal chemotherapy. The event-free survival (EFS) experience for patients with 1 cerebrospinal fluid (CSF) sample contaminated with blast cells was worse than that for patients with no contaminated CSF samples (P =.026); that of patients with 2 consecutive contaminated CSF samples was particularly poor (5-year EFS = 46 +/- 9%). In a Cox multiple regression analysis, the strongest prognostic indicator was 2 consecutive contaminated CSF samples, with a hazard ratio of 2.39 (95% confidence interval, 1. 36-4.20). These data indicate that contamination of CSF with circulating leukemic blast cells during diagnostic lumbar puncture can adversely affect the treatment outcome of children with ALL and is an indication to intensify intrathecal therapy.

Safety of lumbar puncture for children with acute lymphoblastic leukemia and thrombocytopenia

CONTEXT

Patients with thrombocytopenia are at risk for spontaneous or procedure-related hemorrhage. Whether such patients can safely undergo lumbar puncture (LP) without prophylactic platelet transfusion is unknown.

OBJECTIVE

To determine whether an association exists between thrombocytopenia and LP complications among children with acute lymphoblastic leukemia.

DESIGN, SETTING, AND PATIENTS

Retrospective review of the records of 958 consecutive children (median age, 5.5 years) with newly diagnosed acute lymphoblastic leukemia who were treated at a pediatric cancer center between February 1984 and July 1998.

INTERVENTIONS

All patients underwent a diagnostic LP followed by a median of 4 LPs to instill intrathecal chemotherapy.

MAIN OUTCOME MEASURE

Serious complications of LP occurring during the remission induction and consolidation treatment periods (when thrombocytopenia is likely to occur), defined as any neurologic, infectious, or hemorrhagic problems related to the procedure, reported by platelet count at the time of the procedure.

RESULTS

Of the 5223 LPs evaluated, 29 were performed at platelet counts of 10 x 10(9)/L or less, 170 at platelet counts of 11 to 20 x 10(9)/L, and 742 at platelet counts of 21 to 50 x 10(9)/L. No serious complications were encountered, regardless of the platelet count. The 95% confidence interval for the proportion of serious complications in the 199 patients with platelet counts of 20 x 10(9)/L or less was 0% to 1.75% and that for the 941 patients with platelet counts of 50 x 10(9)/L or less was 0% to 0.37%.

CONCLUSIONS

In our study of children undergoing remission induction or consolidation therapy for acute lymphoblastic leukemia, serious complications of LP were not observed, regardless of platelet count. Prophylactic platelet transfusion is not necessary in children with platelet counts higher than 10 x 10(9)/L. Due to the small number of patients in our study with platelet counts of 10 x 10(9)/L or less, conclusions cannot yet be drawn for such patients. JAMA. 2000;284:2222-2224.

Clinical importance of minimal residual disease in childhood acute lymphoblastic leukemia

By using rapid flow cytometric techniques capable of detecting one leukemic cell in 10(4) normal cells, we prospectively studied minimal residual disease (MRD) in 195 children with newly diagnosed acute lymphoblastic leukemia (ALL) in clinical remission. Bone marrow aspirates (n = 629) were collected at the end of remission induction therapy and at 3 intervals thereafter. Detectable MRD (ie, > or = 0.01% leukemic mononuclear cells) at each time point was associated with a higher relapse rate (P < .001); patients with high levels of MRD at the end of the induction phase (> or = 1%) or at week 14 of continuation therapy (> or = 0.1%) had a particularly poor outcome. The predictive strength of MRD remained significant even after adjusting for adverse presenting features, excluding patients at very high or very low risk of relapse from the analysis, and considering levels of peripheral blood lymphoblasts at day 7 and day 10 of induction therapy. The incidence of relapse among patients with MRD at the end of the induction phase was 68% +/- 16% (SE) if they remained with MRD through week 14 of continuation therapy, compared with 7% +/- 7% if MRD became undetectable (P = .035). The persistence of MRD until week 32 was highly predictive of relapse (all 4 MRD(+) patients relapsed vs 2 of the 8 who converted to undetectable MRD status; P = .021). Sequential monitoring of MRD by the method described here provides highly significant, independent prognostic information in children with ALL. Recent improvements in this flow cytometric assay have made it applicable to more than 90% of all new patients. (Blood. 2000;96:2691-2696)

Adverse effect of anticonvulsants on efficacy of chemotherapy for acute lymphoblastic leukaemia

BACKGROUND

Many antileukaemic agents or their metabolites are inactivated by liver enzymes. Most anticonvulsant drugs induce drug-metabolising enzymes and thereby increase the clearance of anticancer agents. We investigated whether anticonvulsants compromise the efficacy of cancer chemotherapy.

METHODS

We identified whom of 716 children treated consecutively for acute lymphoblastic leukaemia at a single academic hospital in the USA between 1984 and 1994 received treatment for 30 days or longer with anticonvulsants (phenytoin, phenobarbital, carbamazepine, or a combination) at the same time as antileukaemic therapy. Cox's proportional-hazards models were used to assess the prognostic significance of anticonvulsants on event-free survival and risk of haematological and central-nervous-system (CNS) relapse, with stratification for treatment protocol.

FINDINGS

40 (5.6%) of 716 patients received anticonvulsants. Use of these drugs was associated with age over 10 years (p=0.003), non-hyperdiploid leukaemia (p=0.031), and T-cell immunophenotype (p=0.022). After adjustment for age and ploidy, anticonvulsant therapy was significantly related to worse event-free survival (hazard ratio 2.67 [95% CI 1.50-4.76]; p=0.0009), haematological relapse (3.40 [1.69-6.88]; p=0.0006), and CNS relapse (2.90 [1.01-8.28]; p=0.047) among the 566 patients with B-lineage leukaemia. No such associations were seen among the 114 patients with T-cell leukaemia (p=0.61, 0.35, and 0.53, respectively). Faster clearance of teniposide (p=0.0001) and methotrexate (p=0.051), but not cytarabine (p=0.26) was found among patients receiving anticonvulsants.

INTERPRETATION

Long-term anticonvulsant therapy increases the systemic clearance of several antileukaemic agents and is associated with lower efficacy of chemotherapy. Alternatives to enzyme-inducing anticonvulsants should be prescribed for patients receiving chemotherapy for acute lymphoblastic leukaemia.

Late effects in survivors of infant leukemia

Little is known about the incidence of and risk factor for late effects of infant leukemia. We evaluated 19 children with acute lymphoblastic leukemia and 15 with acute myeloid leukemia who were diagnosed at age 12 months or younger and have survived for more than 5 years after the diagnosis (median length of follow-up, 13 years; range, 5.7-29 years). Ten patients received chemotherapy alone (group A), 17 received chemotherapy and CNS-directed radiation therapy (CRT) (group B), and seven received chemotherapy, CRT and bone marrow transplantation (group C). The most frequently observed late sequelae included problems in growth (66% of survivors), learning (50%), hypothyroidism (15%), and pubertal development (12%). Cataract, cardiac and hearing abnormalities occurred in 6% of patients. Only eight patients (24%) survive without late effects. In comparison to patients in group A, patients in groups B and C had a higher incidence of having at least one late complication (P = 0.009), a greater decrease in height Z score at 5 years after diagnosis (P = 0.023), and a higher incidence of academic difficulties (P = 0.004). The estimated odds of academic difficulties increased by 18% (P = 0.032) for each month younger in age at the time of CRT. These results indicate that late sequelae are common in longterm survivors of infant leukemia and are often related to CRT and the patient's age at the time of CRT.

Hypersensitivity or development of antibodies to asparaginase does not impact treatment outcome of childhood acute lymphoblastic leukemia

PURPOSE

Development of antibodies and hypersensitivity to asparaginase are common and may attenuate asparaginase effect. Our aim was to determine the relationship between antiasparaginase antibodies or hypersensitivity reactions and event-free survival (EFS).

PATIENTS AND METHODS

One hundred fifty-four children with acute lymphoblastic leukemia received Escherichia coli asparaginase 10,000 IU/m(2) intramuscularly three times weekly for nine doses during multiagent induction and reinduction phases and for seven monthly doses during continuation treatment. Erwinia asparaginase was used in case of clinical hypersensitivity to E coli but not for subclinical development of antibodies. Plasma antiasparaginase antibody concentrations were measured on day 29 of induction in 152 patients.

RESULTS

Antibodies were detectable in 54 patients (35.5%), of whom 30 (55.6%) exhibited hypersensitivity to asparaginase. Of the 98 patients who had no detectable antibodies, 18 (18.4%) had allergic reactions. Patients with antibodies were more likely to have a reaction than those without antibodies (P <.001). Among the 50 patients who experienced allergic reactions (including two for whom antibodies were not measured), 36 (72.0%) were subsequently given Erwinia asparaginase; seven (19.4%) reacted to this preparation. EFS did not differ among patients who did and did not have antibodies (P =.54), with 4-year EFS (+/- 1 SE) of 83% +/- 6% and 76% +/- 5%, respectively. Similarly, EFS did not differ among patients who did and did not develop allergic reactions (P =.68), with 4-year estimates of 82% +/- 6% and 78% +/- 5%, respectively.

CONCLUSION

In this setting, in which most patients with allergy were switched to another preparation, there was no adverse prognostic impact of clinical or subclinical allergy to asparaginase.

Alternating drug pairs with or without periodic reinduction in children with acute lymphoblastic leukemia in second bone marrow remission: a Pediatric Oncology Group Study

BACKGROUND

Children with acute lymphoblastic leukemia (ALL) who experience hematologic recurrence while receiving chemotherapy or within 6 months after its cessation have a low cure rate. In this study (Pediatric Oncology Group Protocol 8303) two methods were examined for improving the outcome in these children.

METHODS

After remission induction with prednisone, vincristine, daunorubicin, and asparaginase (PVDA) and consolidation chemotherapy with teniposide and cytarabine, patients received weekly continuation chemotherapy with rotating pairs of drugs, comprised of teniposide and cytarabine and vincristine and cyclophosphamide. In addition, they were randomized to receive or not receive repeated reinduction with PVDA. Patients with matched sibling donors were allowed to receive allogeneic bone marrow transplantation (BMT) instead of continued chemotherapy.

RESULTS

Of 297 evaluable patients 258 (87%) achieved second complete hematologic remission. However, only 23 of these patients remained continuously free of leukemia > or =7 years after chemotherapy or BMT. Neither PVDA pulses nor BMT appeared to influence outcome at a statistically significant level.

CONCLUSIONS

The results of the current study confirm prior reports of the low cure rate of children with ALL who experience hematologic recurrence during initial therapy or shortly after its cessation. New approaches are needed to prevent and retreat hematologic recurrence in pediatric ALL patients.

Mercaptopurine therapy intolerance and heterozygosity at the thiopurine S-methyltransferase gene locus

BACKGROUND

Patients with acute lymphoblastic leukemia are often treated with 6-mercaptopurine, and those with homozygous deficiency in thiopurine S-methyltransferase (TPMT) enzyme activity have an extreme sensitivity to this drug as a result of the accumulation of higher cellular concentrations of thioguanine nucleotides. We studied the metabolism, dose requirements, and tolerance of 6-mercaptopurine among patients with different TPMT phenotypes.

METHODS

We compared, by use of statistical modeling, 6-mercaptopurine pharmacology and tolerance in 180 patients who achieved remission on St. Jude Children's Research Hospital Protocol Total XII composed of weekly methotrexate (40 mg/m(2)) and daily oral 6-mercaptopurine (75 mg/m(2)) given for 2.5 years, interrupted every 6 weeks during the first year for treatment with either high-dose methotrexate or teniposide plus cytarabine. Statistical tests were two-sided.

RESULTS

Erythrocyte concentrations of thioguanine nucleotides (pmol/8 x 10(8) erythrocytes) were inversely related to TPMT enzyme activity (P<.01), with averages (+/- standard deviations) of 417 (+/-179), 963 (+/-752), and 3565 (+/-1282) in TPMT homozygous wild-type (n = 161), heterozygous (n = 17), and homozygous-deficient (n = 2) patients, respectively. There was complete concordance between TPMT genotype and phenotype in a subset of 28 patients for whom TPMT genotype was determined. There were no sex differences in thioguanine nucleotide concentrations (P =.24), TPMT enzyme activity (P =.22), or average weekly prescribed dose of 6-mercaptopurine (P=.49). The cumulative incidence of 6-mercaptopurine dose reductions due to toxicity was highest among patients homozygous for mutant TPMT (100%), intermediate among heterozygous patients (35%), and lowest among wild-type patients (7%) (P<.001), with average (+/- standard deviation) final weekly 6-mercaptopurine doses of 72 (+/-60), 449 (+/-160), and 528 (+/-90) mg/m(2), respectively. Lowering doses of 6-mercaptopurine in TPMT heterozygotes and in deficient patients allowed administration of full protocol doses of other chemotherapy while maintaining high thioguanine nucleotide concentrations.

CONCLUSION

We conclude that genetic polymorphism in TPMT is an important determinant of mercaptopurine toxicity, even among patients who are heterozygous for this trait.

Bacillus cereus causing fulminant sepsis and hemolysis in two patients with acute leukemia

PURPOSE

Hemolysis is so rarely associated with Bacillus cereus sepsis that only two very well documented cases have been reported. This article reports two unusual cases of Bacillus cereus sepsis with massive intravascular hemolysis in patients who had acute lymphoblastic leukemia (ALL).

PATIENTS AND METHODS

A 20-year-old woman who was 9 weeks pregnant experienced a relapse of ALL. A therapeutic abortion was performed. During week 4 of reinduction the patient had abdominal pain, nausea, and vomiting, with severe neutropenia but no fever. Her condition deteriorated rapidly with cardiovascular collapse, acute massive intravascular hemolysis, and death within hours of the onset of symptoms. Blood cultures were positive for Bacillus cereus. Postmortem histologic examination and cultures revealed Bacillus cereus and Candida albicans in multiple organs. The second patient, a 10-year-old girl, presented with relapsed T-cell ALL. In the second week of reinduction, she had abdominal pain followed by hypotension. Again, no fever was noted. Laboratory studies showed intravascular hemolysis 12 hours after admission. Aggressive support was promptly initiated. Despite disseminated intravascular coagulation; cardiovascular, hepatic, and renal failure; and multiple intracerebral hypodense lesions believed to be infarcts, the patient recovered fully and resumed reinduction therapy.

CONCLUSIONS

Bacillus cereus infection can have a fulminant clinical course that may be complicated by massive intravascular hemolysis. This pathogen should be suspected in immunosuppressed patients who experience gastrointestinal symptoms and should not be precluded by the absence of fever, especially if steroids such as dexamethasone are being given. Exchange transfusion may be lifesaving in Bacillus cereus septicemia associated with massive hemolysis.

High incidence of secondary brain tumours after radiotherapy and antimetabolites

BACKGROUND

Brain tumours rarely occur in survivors of childhood acute lymphoblastic leukaemia after cranial radiotherapy. An unusually high frequency of brain tumours seen among children enrolled in one of our leukaemia treatment protocols, Total Therapy Study XII, prompted us to identify the potential causes of this complication.

METHODS

We assessed clinical, biological, and pharmacokinetic features in all 52 children who received prophylactic cranial radiotherapy. We compared the cumulative incidence of brain tumours between subgroups, and with that of 421 children who received radiotherapy in previous studies.

FINDINGS

The incidence of brain tumours among irradiated children (six of 52, 12.8% [SE 5.0]) was high compared with patients in the same study who did not receive radiotherapy (none of 101; p=0.0008) and with other protocols that included cranial radiotherapy (p<0.0001). Of the six children, four had erythrocyte concentrations of thioguanine nucleotide metabolites higher than the 70th percentile for the entire cohort, and three had a genetic defect in thiopurine catabolism. The 8-year cumulative incidence of brain tumour among children with defective versus wild-type thiopurine methyltransferase phenotype was 42.9% (SE 20.6) versus 8.3% (4.7; p=0.0077). This protocol differed from previous protocols, in that more intensive systemic antimetabolite therapy was given before and during radiotherapy.

INTERPRETATION

These data support the elimination of prophylactic radiotherapy for acute lymphoblastic leukaemia except in patients at high risk of central-nervous-system relapse. Underlying genetic characteristics and treatment variables may be associated with an increased risk of radiation-associated brain tumours.

Phase I targeted systemic exposure study of paclitaxel in children with refractory acute leukemias

Clearance of anticancer drugs in children is highly variable, leading to wide variability in the systemic exposure associated with each dosage escalation in Phase I studies. The purpose of this Phase I study was to escalate targeted systemic exposure to paclitaxel, rather than dose, to attenuate the impact of pharmacokinetic variability at each escalation level. Children with recurrent acute leukemias received paclitaxel as 24-h infusions at escalating levels of paclitaxel systemic exposure [i.e., area under the concentration-versus-time curve (AUC)]. Plasma paclitaxel concentrations were measured by high-performance liquid chromatography-UV detection. A Bayesian algorithm using a two-compartment model with saturable distribution and saturable elimination was used to estimate clearance during the first 8 h of infusion; the infusion rate was adjusted 12 h after the start of infusion to achieve the target AUC. Toxicity and evidence of activity were assessed after each course. Six boys and one girl received eight courses of paclitaxel. The target AUC ranged from 31.5 to 45 microM x h. Five of the seven evaluable courses had AUCs between 75% and 125% of the target after adjustment (median, 100.2%; range, 51-151%), whereas none of the seven courses was projected to be in the target range had no change in dose been made (P = 0.021). The ratio of the achieved AUC to the target AUC was inversely related to clearance (r = -0.857; P = 0.014). Mucositis was the exposure-limiting toxicity, at AUCs lower than were expected based on Phase I studies in children with solid tumors. Pharmacokinetically-guided dosing strategies reduced variability in systemic exposure. Alternatives to traditional Phase I studies may be important in the setting of childhood leukemias because these patients show poor tolerance to Phase I therapy.

Sex differences in prognosis for children with acute lymphoblastic leukemia

PURPOSE

Whether recent improvements in the treatment of childhood acute lymphoblastic leukemia (ALL) have nullified the adverse prognosis associated with male sex remains unclear. Therefore, we analyzed the survival experience and presenting clinical and laboratory features of boys and girls with newly diagnosed ALL who were treated at our institution over the past three decades.

PATIENTS AND METHODS

One thousand one hundred fifty-one boys and 904 girls were treated in 13 consecutive Total Therapy studies between 1962 and 1994. An overview analysis was used to investigate the impact of sex on overall and event-free survival, both for the entire cohort and for subgroups defined by treatment era and blast-cell immunophenotype. Stratified analyses were performed to adjust for treatment protocol and known risk factors, and in the modern treatment era, for protocol, immunophenotype, and the DNA content of leukemic cells (ie, DNA index). The pharmacokinetics of methotrexate, teniposide, and cytarabine, as well as the thiopurine methyltransferase activity of erythrocytes, were compared between boys and girls treated on a single protocol.

RESULTS

Compared with girls, boys were more likely to have T-cell ALL (20.9% v 10.7%, P < .001) and seemed less likely to have a favorable DNA index (17.8% v 25.1%, P = .072). There were no other statistically significant differences between the two sexes with respect to presenting features, including leukemic-cell genetic abnormalities, nor were there significant sex differences in the pharmacokinetics of methotrexate, teniposide, or cytarabine or in erythrocyte thiopurine methyltransferase activity. Girls clearly fared better than boys (P < .001) on protocols used during the early era of treatment (10-year event-free survival +/- 1 SE, 43.1%+/-2.1% v 31.5%+/-1.7%). Although prognosis improved for both sexes in the modern era, the difference in outcome between girls and boys persisted (P = .025) (10-year event-free survival, 73.4%+/-3.7% v 63.5%+/-4.0%). However, stratification of modern-era patients by protocol, immunophenotype, and DNA index mitigated statistical evidence of a sex difference in overall survival (P = .263) and event-free survival (P = .124).

CONCLUSION

Although boys and girls alike have benefited from improvements in ALL therapy, these gains have not completely eliminated the sex difference in prognosis that has persisted since the early 1960s. The apparent difference in outcome is partially explained by differences between boys and girls in the distributions of ALL immunophenotype and DNA index.

Low frequency of TEL-AML1 in relapsed acute lymphoblastic leukemia supports a favorable prognosis for this genetic subgroup

The long-term outcome of children with TEL-AML1-positive acute lymphoblastic leukemia (ALL) is uncertain. Although studies of newly diagnosed cases have indicated that the TEL-AML1 fusion confers a favorable prognosis, analyses of relapsed cases have suggested that this may not be true. Because of treatment implications for this subgroup of patients, we have now analyzed 49 cases of relapsed ALL for the presence of TEL-AML1. Only 10% of these cases expressed the fusion, compared to 20-25% of newly diagnosed ALL cases. Additional follow-up of the cohort of 48 newly diagnosed patients with the TEL-AML1 fusion previously reported showed that the 10-year cumulative risk of relapse was 9 +/- 5% (s.e.). Together, these results suggest an excellent outcome for TEL-AML1-positive ALL.

Secondary brain tumors in children treated for acute lymphoblastic leukemia at St Jude Children's Research Hospital

PURPOSE

To evaluate the incidence of and potential risk factors for second malignant neoplasms of the brain following treatment for childhood acute lymphoblastic leukemia (ALL).

PATIENTS AND METHODS

The study population consisted of 1,612 consecutively enrolled protocol patients treated on sequential institutional protocols for newly diagnosed ALL at St Jude Children's Research Hospital (SJCRH) between 1967 and 1988. The median follow-up duration is 15.9 years (range, 5.5 to 29.9 y).

RESULTS

The cumulative incidence of brain tumors at 20 years is 1.39% (95% confidence interval [CI], 0.63% to 2.15%). Twenty-two brain tumors (10 high-grade gliomas, one low-grade glioma, and 11 meningiomas) were diagnosed among 21 patients after a median latency of 12.6 years (high-grade gliomas, 9.1 years; meningiomas, 19 years). Tumor type was linked to outcome, with patients who developed high-grade tumors doing poorly and those who developed low-grade tumors doing well. Risk factors for developing any secondary brain tumor included the presence of CNS leukemia at diagnosis, treatment on Total X therapy, and the use of cranial irradiation, which was dose-dependent. Age less than 6 years was associated with an increased risk of developing a high-grade glioma.

CONCLUSION

This single-institution study, with a high rate of long-term data capture, demonstrated that brain tumors are a rare, late complication of therapy for ALL. We report many more low-grade tumors than others probably because of exhaustive long-term follow-up evaluation. The importance of limiting cranial radiation is underscored by the dose-dependent tumorigenic effect of radiation therapy seen in this study.

Reappraisal of the clinical and biologic significance of myeloid-associated antigen expression in childhood acute lymphoblastic leukemia

PURPOSE

To reassess the clinical and biologic significance of myeloid-associated antigen expression in childhood acute lymphoblastic leukemia (ALL).

PATIENTS AND METHODS

We prospectively studied 334 newly diagnosed cases of this disease, using a comprehensive panel of antibodies that represented five myeloid cluster groups (CD13, CD14, CD15, CD33, and CD65). Blast cells were tested for ETV6 and MLL rearrangement using Southern blot analysis.

RESULTS

CD13 was expressed in 13.7% of cases, CD14 in 1%, CD15 in 6.6%, CD33 in 16%, and CD65 in 9.7%. Approximately one third of cases (31.4%) expressed one or more of these antigens (B-cell precursor, 31.9%; T-cell, 28.8%), while 10.5% expressed two or more (B-cell precursor, 11.3%; T-cell, 6.1%). Among the B-cell precursor leukemias, myeloid-associated antigen expression was significantly associated with a lack of hyperdiploidy and rearrangements of ETV6 or MLL gene. Most of the cases with MLL rearrangements (82%) expressed CD65, CD15, and CD33, either alone or in combination, whereas 48% of those with a rearranged ETV6 gene expressed CD13, CD33, or both. Myeloid-associated antigen expression did not correlate with event-free survival, whether the analysis was based on any of the five antigens in our panel or on the three more commonly tested antigens (CD13, CD33, and CD65). Importantly, this finding was not affected by exclusion of patients with ETV6 or MLL gene rearrangements.

CONCLUSION

Even though blast cell expression of myeloid-associated antigen expression shows significant associations with specific genetic abnormalities, it lacks prognostic value in childhood ALL.

Anti-asparaginase antibodies following E. coli asparaginase therapy in pediatric acute lymphoblastic leukemia

Asparaginase is an effective antileukemic agent and is included in most front-line protocols for pediatric acute lymphoblastic leukemia (ALL) worldwide; however, allergic reactions to asparaginase may be dose-limiting. We evaluated plasma anti-asparaginase antibody concentrations in a cohort of children with newly diagnosed ALL, who did and who did not exhibit clinical hypersensitivity, after Escherichia coli (E. coli) asparaginase therapy. Thirty-five children who received asparaginase 10000 IU/m2 i.m. three times weekly for nine doses as part of both multiagent induction and reinduction chemotherapy, and seven monthly doses during the first 7 months of continuation treatment, were studied. Twenty-two patients experienced initial allergic reactions to asparaginase during continuation (n=20) or reinduction (n=2) phases and 13 children did not exhibit any reaction. An enzyme-linked immunosorbent assay (ELISA) was used to measure anti-asparaginase antibodies in plasma samples, diluted 1:3200, using E. coli asparaginase as the antigen. The median anti-asparaginase antibody concentration (OD at 1:3200 dilution) increased from 0.039 at induction to 0.506 at reinduction in patients who exhibited clinical hypersensitivity (P = 0.0002). By comparison, median antibody level increased from 0.011 to 0.032 OD at identical time points in patients who did not react to asparaginase (P = 0.02). Both post-induction and post-reinduction anti-asparaginase antibody levels were higher in reacting than in nonreacting patients (P = 0.004 and P = 0.01, respectively). Antibody levels were inversely related to the time elapsed between the reaction and sampling (P = 0.011). Although anti-asparaginase antibody levels increased from the post-induction plasma sample to the post-reinduction sample in 28 of 35 patients regardless of whether they exhibited clinical hypersensitivity, patients with hypersensitivity reactions had higher antibody levels than did identically treated control patients at comparable time points in therapy. Therefore, antibody analysis may be of clinical value in predicting future hypersensitivity.

Transient encephalopathy following high-dose methotrexate treatment in childhood acute lymphoblastic leukemia

The purpose of this study was to determine the incidence of and pharmacokinetic parameters associated with the development of transient encephalopathy following the administration of high-dose methotrexate and intrathecal chemotherapy in children with acute lymphoblastic leukemia (ALL). Two hundred and fifty-nine children with newly diagnosed ALL treated on one of two consecutive trials were analyzed. Presenting features in patients who developed transient encephalopathy were compared with those of patients who did not experience this event. For each patient who developed transient encephalopathy, methotrexate pharmacokinetic parameters were compared with those of matched controls. The cumulative incidence of acute encephalopathy was 3% (SE 1%) at 1 year and was associated with age greater than or equal to 10 years at diagnosis. Pharmacokinetic data did not differ between patients who developed transient encephalopathy and those who did not. The majority of patients had no long-term sequelae and were able to receive further courses of methotrexate without modification. Transient focal neurologic deficits occur in about 3% of children with ALL following the administration of intravenous and intrathecal methotrexate. These events cannot be predicted by pharmacokinetic parameters Of methotrexate disposition. However, these events are generally benign, suggesting that patients who experience acute encephalopathy should continue to receive this important chemotherapeutic agent.

Early intensification of intrathecal chemotherapy virtually eliminates central nervous system relapse in children with acute lymphoblastic leukemia

Central nervous system (CNS) relapse has been an obstacle to uniformly successful treatment of childhood acute lymphoblastic leukemia (ALL) for many years. We therefore intensified intrathecal chemotherapy (simultaneously administered methotrexate, hydrocortisone, and cytarabine) for 165 consecutive children with newly diagnosed ALL enrolled in Total Therapy Study XIIIA from December 1991 to August 1994. The 64 patients (39%) who had 1 or more blast cells in cytocentrifuged preparations of cerebrospinal fluid at diagnosis, with or without associated higher-risk features, received additional doses of intrathecal chemotherapy during remission induction and the first year of continuation treatment. Patients with higher-risk leukemia, regardless of cerebrospinal fluid findings, also received additional doses of intrathecal chemotherapy during the first year of continuation treatment. Cranial irradiation was reserved for patients with higher-risk leukemia (22% of the total). The 5-year cumulative risk of an isolated CNS relapse among all 165 patients was 1.2% (95% confidence interval, 0% to 2.9%), whereas that of any CNS relapse was 3.2% (0. 4% to 6.0%). The probability of surviving for 5 years without an adverse event of any type was 80.2% +/- 9.2% (SE). Our results suggest that early intensification of intrathecal chemotherapy will reduce the risk of CNS relapse to a very low level in children with ALL, securing a higher event-free survival rate overall.

Immunological detection of minimal residual disease in children with acute lymphoblastic leukaemia

BACKGROUND

The clinical significance of submicroscopic levels of leukaemic cells in bone-marrow aspirates from children with acute lymphoblastic leukaemia (ALL) remains controversial. We prospectively determined the frequency and prognostic importance of minimal residual disease detected by a rapid immunological assay in bone-marrow aspirates of children with ALL.

METHODS

158 children with newly diagnosed ALL received 6 weeks of remission-induction chemotherapy. Once complete clinical remission was attained the patients received 2 weeks of consolidation therapy followed by continuation therapy. Bone-marrow aspirates were collected after induction therapy and during weeks 14, 32, and 56 of continuation therapy, and then at 120 weeks (end of therapy). Cells with leukaemia-associated immunophenotypes were investigated by multiparameter flowcytometry capable of detecting one leukaemic cell among 10,000 normal cells.

FINDINGS

The proportion of patients with detectable leukaemic cells was 23% at remission induction and 17% at week 14 of continuation therapy, decreasing to 5% and 4% at weeks 32 and 56. None of the 65 samples examined at completion of therapy (week 120) showed evidence of disease. Detectable residual disease at the end of remission induction correlated with adverse genetic abnormalities--the Philadelphia chromosome and MLL gene rearrangements--but not with other presenting features. Detectable leukaemia was associated with subsequent relapse regardless of the time at which bone-marrow samples were examined (p < 0.002 for all comparisons). For example, 3-year cumulative incidence (SE) of relapse in patients with and without detectable leukaemia at remission induction was 32.5% (10.6) and 7.5% (4.0), respectively (p < 0.001); for tests done at week 14, it was 42.1% (14.6) and 6.6% (3.5), p < 0.001. These correlations remained significant after adjusting for adverse presenting features. A higher degree of marrow infiltration by leukaemic cells (> or = 0.1%) in week 14 samples identified a subset of patients with an especially poor prognosis.

INTERPRETATION

Immunological detection of residual leukaemic cells at any point in the treatment course is a powerful predictor of relapse in children with ALL. Alternative treatment should be considered for cases with persistent disease beyond the first 3 months of continuation therapy.

12p abnormalities and the TEL gene (ETV6) in childhood acute lymphoblastic leukemia

Although abnormalities involving the short arm of chromosome 12 (12p) are one of the most frequently observed rearrangements in childhood acute lymphoblastic leukemia (ALL), little is known about the frequency of different structural abnormalities and their relationship to the status of the ETV6 (also named TEL) gene in this region. Of 815 children with newly diagnosed ALL, 94 (11.5%) had a total of 104 cytogenetic 12p abnormalities. Loss of genetic material was observed in 67 (64%) of these abnormalities. Cases with 12p alterations had a much lower frequency of hyperdiploidy greater than 50 (7%) than did the ALL population in general, but these cases had a similar distribution of immunophenotype and similar 5-year event-free survival (70% +/- 5% SE v 64% +/- 2%, P = .64). Rearrangement of the ETV6 gene was identified in 36 (56%) of 64 cases evaluated. The ETV6-CBFA2 (TEL-AML1) fusion transcript was found in 25 (66%) of 38 cases evaluated, and all but one of these showed ETV6 rearrangement. Importantly, ETV6 rearrangement was associated with a favorable prognosis (5-year event-free survival: 89% +/- 6% v 60% +/- 1%, P < .01). We conclude that most but not all 12p cytogenetic abnormalities in childhood ALL involve ETV6, and that rearrangement of ETV6 is associated with a favorable treatment outcome.

Urate oxidase in prevention and treatment of hyperuricemia associated with lymphoid malignancies

Standard prophylaxis and treatment of malignancy-associated hyperuricemia in the USA has been allopurinol with vigorous hydration, urinary alkalinization and osmotic diuresis. Urate oxidase, the enzyme that converts uric acid to allantoin (a readily excreted metabolite that has 5- to 10-fold higher solubility than uric acid), is an alternative therapy; however, few published findings support this practice. Between February 1994 and December 1996, we administered non-recombinant urate oxidase (Uricozyme) to 126 children with newly diagnosed non-B cell acute lymphoblastic leukemia (ALL) during the first 5 days of chemotherapy with methotrexate, 6-mercaptopurine or both. Their blood levels of uric acid and other indicators of tumor lysis were measured at diagnosis and during treatment and then compared with findings in 129 similarly treated historical controls who had received allopurinol to control hyperuricemia. Clinical responses to urate oxidase were also determined in eight patients with newly diagnosed B cell ALL or advanced-stage non-Hodgkin lymphoma. Patients treated with urate oxidase had rapid and significantly greater decreases in their blood uric acid levels than did the historical controls (median maximal level during treatment, 2.3 vs 3.9 mg/dl, P < 0.001). They also had lower creatinine (0.6 vs 0.7 mg/dl, P = 0.01) and blood urea nitrogen (11 vs 24 mg/dl, P < 0.001) levels. Similar findings were made in the eight cases of B cell ALL or non-Hodgkin lymphoma. None of the patients required dialysis for acute renal failure. Six (4.5%) of the 134 children given urate oxidase had allergic reactions, manifested primarily by urticaria, bronchospasm and hypoxemia. Thus, non-recombinant urate oxidase is a more effective uricolytic agent than allopurinol but is associated with acute hypersensitivity reactions, even in patients without a history of allergy.