6-Mercaptopurine Cumulative Dose: A Critical Factor of Maintenance Therapy in Average Risk Childhood Acute Lymphoblastic Leukemia

A multivariate survival analysis including gender, age, log white blood cell (WBC) count, liver and spleen size at diagnosis, mean log WBC count during maintenance therapy, and the prescribed cumulative doses of 6-mercaptopurine (6-MP), methotrexate (MTX), vincristine (VCR), and prednisom (PDN) during maintenance therapy was performed on 53 children with average-risk acute lymphoblastic leukemia (ALL). The 6-MP cumulative dose prescribed during maintenance therapy resulted in the most important statistically significant independent prognostic factor. Patients who received less than the median cumulative dose of 6-MP (86% of planned protocol dose) fared significantly worse than the other patients, regardless of WBC count at diagnosis, gender, age, and other factors studied. Therefore, 6-MP cumulative dose during maintenance therapy may be the critical factor for effective maintenance therapy in childhood ALL.     

Prognostic significance of methotrexate and 6-mercaptopurine dosage during maintenance chemotherapy for childhood acute lymphoblastic leukemia.

Tolerance of full-dose methotrexate/6-mercaptopurine (MTX/6MP) maintenance therapy for childhood acute lymphoblastic leukemia (ALL) without side effects could reflect insufficient systemic drug exposure, and drug withdrawals due to toxicity might reduce the chance of cure. The present study included 122 children with non-B cell acute lymphoblastic leukemia with a median follow-up of 84 months. Leukopenia and hepatotoxicity were calculated as weighted means of all white cell counts and all serum aminotransferase measurements, respectively, registered for each patient. Forty-five patients relapsed (30 in bone marrow). Patients tolerating an average dose of MTX of more than 75% of the recommended protocol doses and having cumulated drug withdrawals of less than 1% of the period of maintenance therapy had an increased risk of hematological relapse (p = 0.008) as well as of any relapse (p = 0.03) when compared to the remaining patients. Patients with a cumulative withdrawal of MTX or of 6MP for greater than 10% of the maintenance therapy period had an increased risk of hematological relapse (MTX: p = 0.009, 6MP: p less than 0.0001) and of any relapse (MTX: p = 0.16, 6MP: p = 0.0002). Liver toxicity was the main reason for cumulative long-term drug withdrawals. However, patients with a mean aminotransferase level above the upper normal limit (40 IU/l) who were kept on therapy (cumulative withdrawals of neither drug for more than 5% of their maintenance therapy period) had a significantly lower risk of hematological relapse (p = 0.02) as well as of any relapse (p = 0.06) than the remaining children. The concept of treating to toxicity seems warranted for maintenance therapy of childhood lymphoblastic leukemia.     

The course of biological parameters and 6-mercaptopurine pharmacokinetics during maintenance treatment of children with acute lymphoblastic leukaemia

Twenty patients on maintenance therapy (MT) for acute lymphoblastic leukaemia (ALL) with oral 6-mercaptopurine (6-MP) and methotrexate (MTX) were studied. White cell and red cell indices and platelets counts were monitored every second week as were drug levels. Mean values for 6-MP and MTX doses, and blood component parameters were calculated for each 6-month period for the whole patient group. 6-MP plasma concentrations and liver-function tests were determined once every six months and mean values calculated. 6-MP and MTX mean doses did not change significantly during MT. The mean area under the concentration versus time curve (AUC) 0-4 hours varied slightly from the start to the end of the MT (257 and 296 ng/ml.h, respectively). The mean plasma peak concentration increased from 98 ng/ml to 195 ng/ml (p less than 0.01) during the same period. There were significant decreases between the initial white blood cell counts (WBC) and red blood cell counts (RBC) as compared to levels at the end of therapy (p less than 0.01 and 0.02, respectively). A linear correlation was found between 6-MP peak concentrations and both WBC (r = 0.96) and RBC (r = 0.87). At the end of MT liver function tests became normal in all except 6 patients. In conclusion, MT have moderate effects on bone marrow and liver and monitoring 6-MP plasma concentration might be of value for determination of the optimal WBC levels during MT.     

The Course of Biological Parameters and 6-Mercaptopurine Pharmacokinetics during Maintenance Treatment of Children with Acute Lymphoblastic Leukaemia

ABSTRACT. Twenty patients on maintenance therapy (MT) for acute lymphoblastic leukaemia (ALL) with oral 6-mercaptopurine (6-MP) and methotrexate (MTX) were studied. White cell and red cell indices and platelets counts were monitored every second week as were drug levels. Mean values for 6-MP and MTX doses, and blood component parameters were calculated for each 6-month period for the whole patient group. 6-MP plasma concentrations and liver-function tests were determined once every six months and mean values calculated. 6-MP and MTX mean doses did not change significantly during MT. The mean area under the concentration versus time curve (AUC) 0-4 hours varied slightly from the start to the end of the MT (257 and 296 ng/ml-h, respectively). The mean plasma peak concentration increased from 98 ng/ml to 195 ng/ml ( p <0.01) during the same period. There were significant decreases betwen the initial white blood cell counts (WBC) and red blood cell counts (RBC) as compared to levels at the end of therapy ( p <0.01 and 0.02, respectively). A linear correlation was found between 6-MP peak concentrations and both WBC ( r =0.96) and RBC ( r =0.87). At the end of MT liver function tests became normal in all except 6 patients. In conclusion, MT have moderate effects on bone marrow and liver and monitoring 6-MP plasma concentration might be of value for determination of the optimal WBC levels during MT.     

急性淋巴细胞性白血病患儿巯嘌呤耐受性研究

目的 调查急性淋巴细胞性白血病(acute lymphoblastie leukemia,ALL)患儿,维持化疗期间巯嘌呤(6-mercaptopurine,6-MP)的耐受性,为进一步研究6-MP耐受性差异的原因提供依据.方法 选择规范应用北京儿童医院急性淋巴细胞性白血病2003年化疗方案(BCH-ALL-2003),随访至2008年9月30日的患儿.全部患儿处于骨髓缓解期,且维持化疗≥13个月.详细记录患儿6-MP服用情况,包括服用剂量以及恶心、呕吐、皮疹等用药反应,以调查6-MP的耐受性.所有患儿每周复查血常规,间隔4周复查肝功能,并根据检查结果进行6-MP毒性分级.记录6-MP停止时间和剂量减少程度.结果共133例,男81例,女52例,中位年龄67个月(18～188个月),中位缓解时间26个月(6～47个月).6-MP维持化疗(13.5±7.4)个月(3～25个月),其中6-MP标准剂量、全疗程者72例(54%),剂量46 ms/(m~2·d),白细胞(WBC)(3～4)×10~9/L,中性粒细胞(ANC)(1.5～2.0)×10~9/L,肝脏毒性小于Ⅱ级,4例(3%)患儿ANC持续在3×10~9/L以上,6-MP剂量增加为标准剂量125%.余61例患儿均为严重不耐受6-MP者,其中骨髓抑制48例(同时伴肝毒性9例),单纯肝脏功能异常12例,反复皮疹1例.平均毒性反应出现时间为2.5周.19例患儿平均停用6-MP 7 d,42例患儿平均6-MP实际剂量25～30 ms/(m~2·d).结论 ALL患儿个体间6-MP的耐受性差异很大,46%ALL患儿对6-MP的标准治疗剂量表现为明显的骨髓抑制和肝功能异常等不耐受反应,临床需要根据血常规不断调整6-MP的剂量,以避免较大的毒性反应的发生,而3%患儿给予标准剂量6-MP,表现为无轻度骨髓抑制等化疗反应,临床需要增加6-MP剂量以减少复发危险性.但如何更准确地进行6-MP剂量调整是临床研究的难题之一.选择6-MP严重不耐受患儿进行6-MP代谢酶活性和基因多态性研究,以明确ALL儿童6-MP耐受性差异的原因,为进一步进行个体化药物剂量的调整提供理论依据.     

Vitamin B12 and folic acid absorption and hematological status in children with postenteritis enteropathy

In a group of nine children with postenteritis enteropathy (i.e., persisting small-intestinal mucosal damage and failure-to-thrive after an acute episode of gastroenteritis), absorption capacities for vitamin B12 and folic acid were studied and compared with hematological status in peripheral blood. The fractional absorptions of vitamin B12 (FAB12) and folic acid (FAFol) were determined by means of a double-isotope technique employing a single-stool-sample test. The children were examined when growth retardation was maximal, and examinations were repeated during the late recovery period. In spite of considerable small-intestinal mucosal damage, only the absorption of vitamin B12 was markedly affected, while that of folic acid was almost intact. When growth retardation was maximal, FAB12 was below the normal age-correlated range in half of the children. FAB12 was also severely reduced in all longitudinally observed children when compared with the results obtained during the late recovery period (p less than 0.005). FAFol was below the normal range in one fourth of the children, but the reduction was modest and insignificant when compared with the results of repeated examinations during the late recovery period. A moderate iron deficiency was detected in half the children. High levels of plasma vitamin B12, folic acid, and erythrocyte folate were detected at both early and later examinations, indicating that these parameters were not affected by the reduced absorption capacities. However, if malabsorption and chronic diarrhea are combined with low dietary intake of vitamin B12, as is the case for many children in the Third World, depletion of vitamin B12 stores may result.     

Biopterin and neurotransmitter amine metabolism in children with acute lymphoblastic leukemia receiving methotrexate therapy

To test the hypothesis that some of the neurologic sequelae of treatment for acute lymphoblastic leukemia (ALL) might be related to abnormalities in biopterin metabolism associated with methotrexate (MTX) therapy, total biopterin levels in cerebrospinal fluid (CSF) and plasma, and homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5HIAA) were measured in a cross-sectional study of 80 children with ALL. For comparison, biopterins were also measured in a group of children of similar age undergoing investigation for neurologic disease. In children with ALL studied before therapy, no significant difference was found between the means of plasma biopterin or CSF biopterin concentrations and the means in the control group. In children receiving MTX, plasma biopterin values were higher in the group given maintenance therapy than in children observed before treatment. CSF levels were significantly increased only in those patients who had completed 2 years of maintenance therapy. CSF concentrations of HVA and 5HIAA in patients with ALL who had received no treatment (median values 52 and 18 ng/ml, respectively) showed a wide scatter and were inversely related to age. In patients receiving MTX, concentrations of these metabolites were higher than in the untreated group, again reaching a peak in patients just completing 2 years of treatment (median HVA 110 ng/ml, 5HIAA 34 ng/ml). These results provide no support for the idea that neurotransmitter amine deficiency occurs in children with ALL receiving MTX, and indicate, rather, that amine and biopterin synthesis increases in such patients.     

Micronutrient status in children with cerebral palsy

AIM: To investigate micronutrient status in a group of children with cerebral palsy (CP). METHODS: Thirty-six children with CP, aged 1.5-17 years, completed a 4-day food diary, underwent anthropometric measurements and delivered blood for analysis of micronutrient concentrations. RESULTS: Low intake of iron, folate, niacin, calcium, vitamin E and vitamin D was common, even among those who were receiving nutritional supplements. Laboratory tests revealed low serum concentration of folate in eight children, alpha-tocopherol in six children, ferritin in five children and pyridoxal-5-phosphate in three children. Two participants were low in zinc and one was low in selenium. Severely disabled children received nutrition supplements more frequently than those with less severe disability (71% vs.16%, p = 0.01). Tube feeding and use of nutrition supplements was reflected in higher concentrations of micronutrients in blood and serum. CONCLUSION: Low intake of micronutrients as well as low micronutrient concentrations was common in this heterogenic group of children with CP. Children with neurological disabilities should have their nutritional status evaluated in order to ascertain sufficient intake of micronutrients.     

Erythrocyte concentrations of metabolites or cumulative doses of 6-mercaptopurine and methotrexate do not predict liver changes in children treated for acute lymphoblastic leukemia

BACKGROUND: During therapy consisting of 6MP and MTX, metabolites accumulate in the erythrocytes. The erythrocyte levels of metabolites reflect the intensity of therapy. Whether they are associated with hepatotoxicity manifested as histological liver changes is not known. We studied the association of the metabolites and cumulative doses of 6MP and MTX with histological liver disease. METHODS: Serial measurements of E-TGN, E-MTX, and ALT during maintenance therapy were performed and cumulative doses of 6MP and MTX were calculated as g/m2 in 16 children with ALL. Each subject underwent a percutaneous liver biopsy at the end of therapy to screen for histological liver disease. RESULTS: No differences in E-TGN, E-MTX, or cumulative doses of 6MP or MTX were detected in the children with ALL with liver fibrosis compared to those without fibrosis, or in the children with less liver fatty change compared to those with more fatty change. Serum median ALT levels correlated significantly positively with cumulative doses of 6MP during therapy (rS = 0.527, P = 0.036), but not with cumulative doses of MTX, or E-TGN, or E-MTX. CONCLUSIONS: Erythrocyte levels of the metabolites or the cumulative doses of 6MP and MTX do not predict histological liver disease in children treated for ALL.     

Maintenance chemotherapy for childhood acute lymphoblastic leukemia: should dosage be guided by white blood cell counts?

In a retrospective population-based study of 122 children with non-B-cell acute lymphoblastic leukemia (ALL), we analyzed the relation between risk of relapse and the degree of leukopenia achieved during oral methotrexate (MTX) and 6-mercaptopurine (6MP) maintenance chemotherapy (MT). After a median follow-up of 62 months for patients still in remission, 43 patients had relapsed (including 28 bone marrow relapses). Patients with a mean white blood cell count during MT (mWBCMT) of less than or equal to 3.5 x 10(9)/L had a significantly lower risk of hematological relapse (p = 0.007) as well as of any relapse (p = 0.02) compared to patients with higher mWBCMT. The clinical advantage of leukopenia could be demonstrated for all risk groups and was not explained by differences in year of diagnosis, gender, age, and white blood cell count at diagnosis, or the prescribed dose of MTX and 6MP. Although prospective studies are needed to establish the benefit of upward dose adjustments to achieve leukopenia, these results indicate a clinical advantage of keeping WBCs low during MT.     

Insulin-like growth factor-I and insulin-like growth factor binding protein-3 during maintenance chemotherapy of acute lymphoblastic leukemia in children.

PURPOSE: To assess the effect of maintenance chemotherapy (MT) on growth factors and growth in children with acute lymphoblastic leukemia (ALL). PATIENTS AND METHODS: Twenty-one children (10 girls, 11 boys) with standard risk pre-B ALL treated with chemotherapy had serum insulin-like growth factor-I (IGF-I), serum IGF binding protein-3 (IGFBP-3) levels, and linear growth and weight data measured every 3 months during MT. The levels of the cytotoxic metabolites of methotrexate (MTX) and 6-mercaptopurine (6MP) (i.e., erythrocyte MTX polyglutamates [E-MTX], and erythrocyte 6-thioguanine nucleotides [E-6TGN]), s-aminotransferases, and white blood counts (WBC) were measured at least monthly. RESULTS: At the beginning of MT, the median IGF-I standard deviation scores (SDS) and IGFBP-3 SDS were -0.52 and -0.09, respectively, which declined during MT to -1.67 (P < 0.001) and -1.82 (P < 0.001), respectively. At the time of diagnosis, the median height SDS was -0.4, which declined during MT to a median height SDS of -0.9 at cessation of therapy. No significant correlations were found between growth factor levels, growth and body mass index (BMI) versus the doses of MTX, and 6MP, E-MTX, E-6TGN, s-aminotransferases, or WBC. CONCLUSIONS: A significant decline in IGF-I, IGFBP-3, and growth retardation may not be directly related to the treatment intensity during MT.     

Milk could decrease the bioavailability of 6-mercaptopurine

The bioavailability of 6-mercaptopurine (6-MP) administered orally for maintenance therapy of children with acute lymphoblastic leukemia is highly variable. Xanthine oxidase (XO) can transform 6-MP into 6-thioxanthine (6-TX) and 6-thiouric acid (6-TUA), which have no therapeutic value. XO is found in high concentration in cow's milk. Incubation at 37 degrees C for 30 min with commercial preparations of pasteurized cow's milk results in transformation of 30% of a clinically relevant concentration of 6-MP into 6-TUA. Milk boiled for 5 min has no effect on the 6-MP. Addition of gastric juice at ratios likely to be seen in children has negligible inhibitory effect on the 6-MP destroying activity of milk. Conversely, folic acid and allopurinol markedly inhibit this effect at clinically relevant concentrations. These observations may help to optimize modalities of administration of 6-MP.     

NUDT15基因型对儿童急性淋巴细胞白血病6-MP个体化治疗的影响

6-巯基嘌呤（6-MP）是急性淋巴细胞白血病（ALL）维持治疗阶段的重要药物，其副作用包括肝毒性和骨髓抑制，不同个体对6-MP的耐受差异较大，6-MP治疗需个体化。巯嘌呤甲基转移酶（TPMT）活性缺乏与6-MP不耐受具有相关性。但亚洲患者TPMT等位基因的突变频率较低。近来发现存在NUDT15基因突变的ALL患者6-MP耐受剂量低于常规剂量。该文就NUDT15基因型对ALL患儿6-MP个体化治疗的影响进行综述。     

Relation Between Maternal and Infant Blood Folate Activities

The relation between maternal and cord blood folate activity was investigated in a group of 110 primigravidae and their infants. Approximately half of these mothers had received folic acid supplements during their pregnancy, and the effects of this on infant blood folate levels at birth and at 6 weeks were also studied.In unsupplemented pregnancies there was a significant relation between infant and maternal blood folate levels at delivery.The results of folic acid supplementation during pregnancy were reflected by higher cord blood values, but 6 weeks after delivery infant plasma folate levels were essentially the same in both groups and independent of maternal supplies before delivery.     

Ratio of methotrexate to folate uptake by lymphoblasts in children with B-lineage acute lymphoblastic leukemia: a pilot study

PURPOSE: Methotrexate (MTX) remains one of the most effective drugs for the treatment of children with acute lymphoblastic leukemia (ALL). Because MTX and 5-methyltetrahydrofolate (5CH3THF) share uptake and metabolic pathways, the efficacy of MTX is likely to depend not only on its metabolism but also on how well folate is accumulated by lymphoblasts. The authors' goal was to compare in vitro folate and antifolate uptake in B-lineage lymphoblasts from patients who remained in continuous complete remission (CCR) and those in whom relapse occurred. PATIENTS AND METHODS: Twenty-four children with B-lineage ALL were studied at diagnosis (n = 20) or relapse (n = 4). Lymphoblasts obtained by bone marrow aspiration were incubated for 24 hours in vitro with 0.05 microM 5CH3[3H]THF or 1 microM [3H]MTX. RESULTS: As of July 1999, 16 patients studied at diagnosis remained in CCR at a median follow-up of 45 months after achieving remission. Two of the patients studied at relapse are in second CCR; the remaining two died from progressive disease. The median uptake of neither [3H]MTX nor 5CH3[3H]THF differed significantly between the 16 patients in first CCR studied at diagnosis and the 4 patients studied at relapse. However, the median ratio of [3H]MTX:5CH3[3H]THF uptake differed significantly for patients who remained in first CCR versus patients studied at relapse. CONCLUSIONS: The uptake of [3H]MTX in relation to 5CH3[3H]THF by leukemic lymphoblasts in vitro may correlate positively with treatment outcome in children with B-lineage ALL. A larger study of homogeneously treated patients is necessary to confirm these results.     

Hematological parameters and cobalamin status in infants born to smoking mothers

Hematological parameters, serum cobalamin and folate levels, and the concentrations of the functional markers plasma methylmalonic acid and total homocysteine were determined in 173 newborns and 46 infants at 6 weeks to see whether maternal smoking influences the hematological parameters and the vitamin status of the newborn. At birth, there was a strong inverse correlation between the number of cigarettes smoked per day during pregnancy and red blood cell count (r = -0.56, p = 0.001) and hemoglobin level (r = -0.52, p = 0.003) in the newborns. Neonates born to smoking mothers had lower red blood cell counts and lower hemoglobin and serum cobalamin levels as compared with infants born to nonsmoking mothers. At 6 weeks, maternal smoking significantly predicted the methylmalonic acid and total homocysteine levels, suggesting an influence from smoking on the cobalamin function in these infants.     

Gene-Environment Interactions and the Risk of Childhood Acute Lymphoblastic Leukemia: Exploring the Role of Maternal Folate Genes and Folic Acid Fortification

Few studies have evaluated the interaction of folic acid fortification and folate metabolic genes on the risk of childhood acute lymphoblastic leukemia (ALL). Because folate status is influenced by both intake and genetic variation, the objective of this study was to explore maternal folate metabolic gene-folic acid fortification interactions and the risk of childhood ALL. The study population consisted of 120 ALL case-parent triads recruited from Texas Children's Cancer Center between 2003 and 2010. For this analysis, we focused on 13 maternal single nucleotide polymorphisms (SNPs) in 5-methyltetrahydrofolate-homocysteine methyltransferase (MTR). Prefortification was defined as delivery before January 1997 and postfortification as delivery in or after January 1997. We used a two-step approach to evaluate gene-environment interactions. First, a case-only approach was used, as this design provides greater power in the assessment of gene-environment interactions compared to other approaches. Second, we confirmed all statistically significant interactions using a log-linear approach among case-parent triads. Only one of 13 interactions evaluated was confirmed in step 2. Specifically, mothers with the minor allele of MTR rs1804742 and who delivered during the prefortification period were at a greater risk of having a child with ALL (OR = 1.54, 95% CI: 0.82–2.88), compared to those mothers who delivered during the postfortification period (OR = 0.81, 95% CI: 0.22–2.99, P for interaction = .03). In one of the few studies to evaluate maternal folate metabolic genotype-folic acid interactions, we found limited evidence that the maternal MTR rs1804742 appeared to interact with higher folic acid levels to influence childhood ALL risk.     

Reduced total plasma homocyst(e)ine in children and adolescents with type 1 diabetes

OBJECTIVES: The objective was to investigate total plasma homocyst(e)ine (tHcy), methylenetetrahydrofolate reductase (MTHFR) genotype, and the contribution of diet to homocysteine values in children and adolescents with type 1 diabetes and a control group. STUDY DESIGN: A total of 78 children with type 1 diabetes and 59 members of an age- and sex-matched control group were recruited. Fasting samples were collected for tHcy, MTHFR genotype, serum vitamin B(12), serum folate, red cell folate, and plasma creatinine. Food frequency questionnaires targeted intake of folate, vitamin B(6), and vitamin B(12). RESULTS: Fasting tHcy was reduced in patients compared with the control group (4.7 vs 5.9 micromol/L, P <.001). Serum folate (P =.002), red cell folate(P <.001), and serum vitamin B(12) (P =.005) were higher, and plasma creatinine was lower. A significant difference in tHcy values between patients and the control group persisted after correction was done for these factors (r = 0.1, P =.02). No difference was seen in the frequency of MTHFR polymorphisms. tHcy was not elevated in those patients with the 677TT or 677T/1298C genotypes, although red cell folate was significantly higher in members of the case (P =.01) and control groups (P =.05) with a 677 TT genotype. Dietary intake of folate correlated with serum folate (r = 0.4,P =.005). CONCLUSION: tHcy values are lower in children and adolescents with type 1 diabetes. Higher serum levels of folic acid and vitamin B(12), reflecting differences in dietary intake between children with diabetes and members of a control group, partially account for this difference.     

Plasma homocysteine levels and folate status in children with sickle cell anemia.

PURPOSE: A sensitive inverse relationship between plasma homocysteine concentration and folate status has been demonstrated. Although children with sickle cell anemia (SCA) are at potential risk for folate deficiency, plasma homocysteine levels have not been reported in such patients. Therefore, a study was designed to assess plasma homocysteine levels as a marker of folate status. DESIGN: Plasma homocysteine concentrations were measured in 120 children with SCA (102 in steady state and 18 during an acute complication) who had never received supplemental folic acid. Folate status was directly assessed in 34 of these patients. RESULTS: Plasma homocysteine levels in the patients with SCA and control subjects were similar. The mean value +/- 1 SD was 5.8+/-2.5 micromol/L (range, 1.6 to 14.1 micromol/L) in the patients with SCA and 6.1+/-2.7 micromol/L (range, 1.7 to 15.3 micromol/L) in 73 pediatric control subjects. In a subpopulation of the study group (34 children), simultaneous serum folate, red cell folate, and total homocysteine concentrations were also measured. Their serum folate and red cell folate concentrations were normal: 12.4+/-10.0 nmol/L (range, 1 to 42 nmol/L) and 604+/-374.7 nmol/L (range, 205 to 1741 nmol/L), respectively. There was no correlation of plasma homocysteine concentration with various clinical or laboratory measures or with red cell folate concentration. CONCLUSION: Folate stores in children with SCA not receiving folic acid supplements are adequate despite an underlying hemolytic anemia.     

High-dose methotrexate improves clinical outcome in children with acute lymphoblastic leukemia: St. Jude Total Therapy Study X

High-dose methotrexate (HDMTX, 1,000 mg/m2) and cranial irradiation/sequential chemotherapy (RTSC) were compared for ability to extend complete remission durations in children with acute lymphoblastic leukemia (ALL). Three hundred thirty patients were enrolled in the study, according to our criteria for standard-risk ALL: a leukocyte count less than 100 X 10(9)/L, no mediastinal mass, no leukemic involvement of the central nervous system (CNS), and blast cells lacking sheep erythrocyte receptors and surface immunoglobulin. Prednisone-vincristine-asparaginase induced complete remissions in 95% of the patients, who were then randomized to receive either HDMTX (n = 154) or RTSC (n = 155). HDMTX was administered with intrathecal MTX for the first 3 weeks following remission induction, and then every 6 weeks with daily mercaptopurine (MP) and weekly oral MTX for a total of 18 months. The RTSC regimen consisted of 1,800 cGy cranial irradiation and intrathecal MTX for 3 weeks, followed by MP/MTX, cyclophosphamide/doxorubicin, and teniposide/cytarabine administered sequentially over 18 months. The final 12 months of treatment for both groups was MP and oral MTX; all patients received intrathecal MTX every 12 weeks. With a median follow-up of 5 years, complete remission durations have been significantly longer among children treated with HDMTX, compared with RTSC (P = .049) or historical institutional control regimens (P = .002). Approximately 67% of the patients receiving HDMTX and 56% of those receiving RTSC are expected to be in continuous complete remission at 4 years. Overall, isolated CNS relapse rates were similar (P = .17) in the two treatment groups, although by newer risk criteria cranial irradiation could be expected to provide better protection in patients with an unfavorable prognosis. These findings indicate that addition of intermittent HDMTX infusions to conventional chemotherapy is an effective method for extending complete remissions in children with ALL.