Methotrexate polyglutamate levels and co-distributions in childhood acute lymphoblastic leukemia maintenance therapy

[Practical management during maintenance therapy of pediatric acute lymphoblastic leukemia: Recommendations of the French Society for Childhood and Adolescent Cancer and Leukemia (SFCE)]

Maintenance therapy is the last phase of treatment for acute lymphoblastic leukemia in children and adolescents. Although maintenance therapy is associated with toxicities and specific management issues, it is an essential phase of treatment that reduces the risk of relapse. The objective of this work is to propose a guide for the initiation, administration, and monitoring of maintenance therapy, and for the management of food, schooling, leisure, community life, risk of infection and links with family medicine.

A Retrospective Cohort Study of the Efficacy, Safety, and Clinical Value of 6-TG versus 6-MP Maintenance Therapy in Children with Acute Lymphoblastic Leukemia

Objective

To explore the efficacy, safety, and clinical value of 6-TG versus 6-MP when treating childhood acute lymphoblastic leukemia (ALL).

Methods

The study period was from January 2017 to June 2021. The subjects of this study were 100 children with ALL who were treated in our hospital. According to different intervention methods, the children who received 6-MP maintenance therapy were selected as the control group, with a total of 57 cases. Children with TG maintenance therapy were included in the research group, a total of 43 cases. The ICNS recurrence rate, non-ICNS recurrence rate, first remission mortality rate, secondary malignant tumor, and other indicators were compared.

Results

First of all, we compared the effective rate: complete remission (CR), partial remission, and nonremission in the study group, and the effective rate was 87.5%. In the control group, there were CR, partial remission, and no remission, and the effective rate was 65.5%. The effective rate of the study group was higher, and the difference between groups was statistically significant (P < 0.05). There were 55 cases of failure in the study group, with an incidence of 21.91%. There were 42 cases of total failure events in the control group, the incidence rate was 18.02%, and there exhibited no remarkable difference (P > 0.05). In the study group, 6 cases died in the first remission, with a fatality rate of 2.39%, while there exhibited no death in the control group. The mortality in the first remission period in the study group was lower (P < 0.05). The overall recurrence rate of the study group was 5.57%, while that of the control group was 11.15%. The overall recurrence rate of the study group was lower, and the difference between groups was statistically significant (P < 0.05). The recurrence rate of ICNS was 2.14% in the study group and 2.98% in the control group, and there exhibited no remarkable difference (P > 0.05). The non-ICNS recurrence rate was 3.43% in the study group and 7.17% in the control group. There exhibited no remarkable difference (P > 0.05). The incidence of secondary malignant tumor events was 0.85% in the study group and 1.59% in the control group. There exhibited no remarkable difference (P > 0.05). The incidence of hepatic vein occlusive disease was 7.29% in the study group and 2.39% in the control group. The incidence of hepatic vein occlusive disease in the study group was higher, and the difference between groups was statistically significant (P < 0.05). Finally, we compared the incidence of adverse reactions. In the study group, there were 12 cases of oral mucosal damage, 7 cases of liver function damage, 6 cases of infection, 10 cases of myelosuppression, 9 cases of gastrointestinal reaction, and 4 cases of skin damage; the incidence rate was 23.17%. In the control group, there were 12 cases of oral mucosal damage, 7 cases of liver function damage, 6 cases of infection, 10 cases of myelosuppression, 9 cases of gastrointestinal reaction, and 4 cases of skin damage, with an incidence of 19.12%. There exhibited no remarkable difference in the incidence of adverse reactions (P > 0.05).

Conclusion

6-TG maintenance therapy in children with ALL can enhance the overall effective rate, can reduce the first remission mortality and the total recurrence rate, and will not increase the overall incidence of adverse reactions, but the incidence of reversible or irreversible hepatic veno-occlusive disease is remarkably increased, which has a certain clinical value.

Background

Treatment-related hepatotoxicity and myelosuppression remain formidable challenges for clinicians. Pharmacokinetic studies found that 6-TG has a more direct intracellular activation pathway, shorter cytotoxic time, and stronger potency than 6-MP. Therefore, this study investigated the efficacy, safety, and clinical value of 6-TG and 6-MP in the treatment of children with ALL.

Socioeconomic position and maintenance therapy in children with acute lymphoblastic leukemia: A national cohort study

BACKGROUND

Socioeconomic differences in survival among children with acute lymphoblastic leukemia (ALL) have been reported in high-income countries and there is an unmet need for strategies to identify vulnerable patient subgroups. Reported differences in survival for children from families with different socioeconomic positions seem to arise when starting maintenance therapy. This could reflect reduced physician's compliance or family adherence to maintenance therapy.

METHODS

This nationwide cohort study with extensive monitoring of systemic methotrexate (MTX)/6-mercaptopurine (6MP) dosing and metabolite levels, retrospectively investigated 173 Danish children treated according to The Nordic Society for Pediatric Hematology and Oncology ALL2008 protocol from 2008 to 2016.

RESULTS

Significantly lower prescribed doses of MTX and 6MP were seen in the children in families with short parental education (short vs. medium vs. higher education: mMTX: 13.8, 16.2, and 18.6 mg/m² /week; p < .01; m6MP: 47.4, 64.9, and 66.1 mg/m² /day; p = .03) or parents unemployed/not in workforce (unemployed/not in workforce vs. mixed vs. at work: mMTX: 15.0, 19.9, and 17.2 mg/m² /week; p < .01; m6MP: 54.8, 72.0, and 65.1 mg/m² /day; p < .01). When assessing family adherence by analyzing MTX and 6MP metabolite levels, including per prescribed dose of MTX and 6MP, we found no significant differences by levels of parental education, affiliation to work market, or income (p > .05 for all comparisons).

CONCLUSIONS

These results indicate that inferior physician compliance to protocol recommendations on drug dosage rather than families' adherence to therapy may contribute to the association between socioeconomic position and cure rates in childhood ALL, although precise mechanisms remain to be explored.

Maintenance therapy for acute lymphoblastic leukemia: basic science and clinical translations

Maintenance therapy (MT) with oral methotrexate (MTX) and 6-mercaptopurine (6-MP) is essential for the cure of acute lymphoblastic leukemia (ALL). MTX and 6-MP interfere with nucleotide synthesis and salvage pathways. The primary cytotoxic mechanism involves the incorporation of thioguanine nucleotides (TGNs) into DNA (as DNA-TG), which may be enhanced by the inhibition of de novo purine synthesis by other MTX/6-MP metabolites. Co-medication during MT is common. Although Pneumocystis jirovecii prophylaxis appears safe, the benefit of glucocorticosteroid/vincristine pulses in improving survival and of allopurinol to moderate 6-MP pharmacokinetics remains uncertain. Numerous genetic polymorphisms influence the pharmacology, efficacy, and toxicity (mainly myelosuppression and hepatotoxicity) of MTX and thiopurines. Thiopurine S-methyltransferase (encoded by TPMT) decreases TGNs but increases methylated 6-MP metabolites (MeMPs); similarly, nudix hydrolase 15 (encoded by NUDT15) also decreases TGNs available for DNA incorporation. Loss-of-function variants in both genes are currently used to guide MT, but do not fully explain the inter-patient variability in thiopurine toxicity. Because of the large inter-individual variations in MTX/6-MP bioavailability and metabolism, dose adjustments are traditionally guided by the degree of myelosuppression, but this does not accurately reflect treatment intensity. DNA-TG is a common downstream metabolite of MTX/6-MP combination chemotherapy, and a higher level of DNA-TG has been associated with a lower relapse hazard, leading to the development of the Thiopurine Enhanced ALL Maintenance (TEAM) strategy-the addition of low-dose (2.5-12.5 mg/m²/day) 6-thioguanine to the 6-MP/MTX backbone-that is currently being tested in a randomized ALLTogether1 trial (EudraCT: 2018-001795-38). Mutations in the thiopurine and MTX metabolism pathways, and in the mismatch repair genes have been identified in early ALL relapses, providing valuable insights to assist the development of strategies to detect imminent relapse, to facilitate relapse salvage therapy, and even to bring about changes in frontline ALL therapy to mitigate this relapse risk.

Thiopurine Enhanced ALL Maintenance (TEAM): study protocol for a randomized study to evaluate the improvement in disease-free survival by adding very low dose 6-thioguanine to 6-mercaptopurine/methotrexate-based maintenance therapy in pediatric and adult patients (0-45 years) with newly diagnosed B-cell precursor or T-cell acute lymphoblastic leukemia treated according to the intermediate risk-high group of the ALLTogether1 protocol

Background

A critical challenge in current acute lymphoblastic leukemia (ALL) therapy is treatment intensification in order to reduce the relapse rate in the subset of patients at the highest risk of relapse. The year-long maintenance phase is essential in relapse prevention. The Thiopurine Enhanced ALL Maintenance (TEAM) trial investigates a novel strategy for ALL maintenance.

Methods

TEAM is a randomized phase 3 sub-protocol to the ALLTogether1 trial, which includes patients 0–45 years of age with newly diagnosed B-cell precursor or T-cell ALL, and stratified to the intermediate risk-high (IR-high) group, in 13 European countries. In the TEAM trial, the traditional methotrexate (MTX)/6-mercaptopurine (6MP) maintenance backbone (control arm) is supplemented with low dose (2.5–12.5 mg/m²/day) oral 6-thioguanine (6TG) (experimental arm), while the starting dose of 6MP is reduced from 75 to 50 mg/m²/day. A total of 778 patients will be included in TEAM during ~ 5 years. The study will close when the last included patient has been followed for 5 years from the end of induction therapy. The primary objective of the study is to significantly improve the disease-free survival (DFS) of IR-high ALL patients by adding 6TG to 6MP/MTX-based maintenance therapy. TEAM has 80% power to detect a 7% increase in 5-year DFS through a 50% reduction in relapse rate. DFS will be evaluated by intention-to-treat analysis. In addition to reducing relapse, TEAM may also reduce hepatotoxicity and hypoglycemia caused by high levels of methylated 6MP metabolites. Methotrexate/6MP metabolites will be monitored and low levels will be reported back to clinicians to identify potentially non-adherent patients.

Discussion

TEAM provides a novel strategy for maintenance therapy in ALL with the potential of improving DFS through reducing relapse rate. Potential risk factors that have been considered include hepatic sinusoidal obstruction syndrome/nodular regenerative hyperplasia, second cancer, infection, and osteonecrosis. Metabolite monitoring can potentially increase treatment adherence in both treatment arms.

Trial registration

EudraCT, 2018–001795-38. Registered 2020-05-15,

Clinicaltrials.gov, NCT04307576. Registered 2020-03-13, https://clinicaltrials.gov/ct2/show/NCT04307576

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09522-3.

DNA-thioguanine concentration and relapse risk in children and young adults with acute lymphoblastic leukemia: an IPD meta-analysis

Methotrexate/6-mercaptopurine maintenance therapy improves acute lymphoblastic leukemia (ALL) outcome. Cytotoxicity is mediated by DNA incorporation of thioguanine nucleotides (DNA-TG). We investigated the association of DNA-TG to relapse risk in 1 910 children and young adults with non-high risk ALL. In a cohort-stratified Cox regression analysis adjusted for sex, age, and white cell count at diagnosis, the relapse-specific hazard ratio (HRa) per 100 fmol/μg increase in weighted mean DNA-TG (wmDNA-TG) was 0.87 (95% CI 0.78-0.97; p = 0.013) in the 839 patients who were minimal residual disease (MRD) positive at end of induction therapy (EOI), whereas this was not the case in EOI MRD-negative patients (p = 0.76). Validation analysis excluding the previously published Nordic NOPHO ALL2008 pediatric cohort yielded a HRa of 0.92 (95% CI 0.82-1.03; p = 0.15) per 100 fmol/μg increase in wmDNA-TG in EOI MRD-positive patients. If also excluding the United Kingdom cohort, in which samples were taken non-randomly in selected patients, the HRa for the EOI MRD-positive patients was 0.82 (95% CI 0.68-0.99; p = 0.044) per 100 fmol/μg increase in wmDNA-TG. The importance of DNA-TG as a biomarker for maintenance therapy intensity calls for novel strategies to increase DNA-TG, although its clinical value may vary by protocol backbone.

Plasma Distribution of Methotrexate and Its Polyglutamates in Pediatric Acute Lymphoblastic Leukemia: Preliminary Insights

BACKGROUND AND OBJECTIVE

High-dose methotrexate (HD-MTX) is the mainstream therapy of current acute lymphoblastic leukemia (ALL) regimens, but frequent intra- and interindividual differences in the clinical response to HD-MTX lead to chemotherapeutic interruption or discontinuation. The exact mechanism of transport across the cell membrane and the disposition of active methotrexate metabolites-methotrexate polyglutamates (MTXPGs)-are not well described in the literature. The aim of this study was to gain more insight into the plasma distribution of methotrexate and MTXPGs in pediatric patients with ALL and to clarify the obscure pathways of MTXPGs.

METHODS

We prospectively measured the concentrations of MTXPG_1-7 in plasma samples from three male pediatric patients treated with HD-MTX and leucovorin rescue according to the IC-BFM 2009 protocol using liquid chromatography-mass spectrometry (LC-MS). Blood samples were obtained at 24, 36, 42, and 48 h after the start of HD-MTX treatment.

RESULTS

Noticeable plasma concentrations of MTXPGs with a 2.2-fold interpatient variability were detected. The highest interindividual variability in total plasma MTXPG concentration was observed at 36 h, and ranged from 13.78 to 30.82 μmol/L. Among all patients, the predominant polyglutamate types in relation to the total plasma MTXPG concentration at each time point were MTXPG₃ (16.71-30.02%) and MTXPG₅ (26.23-38.60%), while MTXPG₇ was the least abundant MTXPG (3.22-5.02%).

CONCLUSION

The presence of MTXPGs in plasma of patients with ALL could be related to the action of ABC efflux transporters on blood cells and hepatocytes resulting from the administration of high doses of methotrexate. This study may not draw definitive conclusions, but it does reduce uncertainty about the dynamics of methotrexate and its active metabolites, which may be of vital importance for achieving a clinical response.

Prevalence of non-adherence and non-compliance during maintenance therapy in adults with acute lymphoblastic leukemia and their associations with survival

OBJECTIVES

Explore patient adherence and physician compliance to protocol guidelines during maintenance therapy, including the association with survival in adults with acute lymphoblastic leukemia (ALL).

METHODS

Blood counts, aminotransferase levels and prescribed 6-mercaptopurine (6MP)/methotrexate (MTX) doses were compared with the protocol guidelines to assess compliance. Non-adherence to the prescribed medication was confirmed in patients with unmeasurable 6MP metabolite levels and suspected in patients with low 6MP metabolites concurrent with aminotransferase and white blood cell count within normal ranges, while potential intermittent non-adherence was defined by >1.9 fold fluctuating 6MP metabolites.

RESULTS

Physicians' non-compliance with insufficient dose increments of 6MP/MTX despite white blood cell counts above the target level comprised a median of 20.1% (interquartile range 9.7-39.3%) of the observed time in maintenance therapy, yet no association to relapse was found (P = .17). Non-adherence to 6MP was confirmed in 9.8% (5 of 51 patients), suspected in an additional 9.8% (5 of 51 patients), and intermittent non-adherence was suspected in 52.6% (20 of 38 patients).

CONCLUSION

Although no association between non-compliance and leukemic relapse was found, likely due to lack of power, increased attention to this phase of ALL therapy is indicated.

Maintenance therapy and risk of osteonecrosis in children and young adults with acute lymphoblastic leukemia: a NOPHO ALL2008 sub-study

PURPOSE

Osteonecrosis is a burdensome treatment-related toxicity that is mostly diagnosed during or soon after 6-mercaptopurine (6MP)/methotrexate (MTX) maintenance therapy for acute lymphoblastic leukemia (ALL), possibly indicating a pathogenic role of these drugs.

METHODS

We prospectively registered symptomatic osteonecrosis during treatment of 1234 patients aged 1.0-45.9 years treated according to the Nordic Society of Hematology and Oncology (NOPHO) ALL2008 protocol. MTX/6MP metabolites were measured as part of the NOPHO ALL2008 maintenance therapy study.

RESULTS

After a median follow-up of 5.6 years [interquartile range (IQR) 3.6-7.5], 68 patients had been diagnosed with symptomatic osteonecrosis. The cumulative incidence was 2.7% [95% confidence interval (CI) 1.6-3.8%] for patients aged < 10 years, 14.9% (95% CI 9.7-20.2%) for patients aged 10.0-17.9 years, and 14.4% (95% CI 8.0-20.8%) for patients aged ≥ 18 years. The median time from diagnosis of ALL to diagnosis of osteonecrosis in these age groups was 1.0 year (IQR 0.7-2.0), 2.0 years (IQR 1.1-2.4), and 2.2 years (IQR 1.8-2.8), respectively (p = 0.001). With 17,854 blood samples available for MTX and 6MP metabolite analysis, neither erythrocyte levels of 6-thioguanine (TG) nucleotides (p > 0.99), methylated 6MP metabolites (p = 0.37), MTX polyglutamates (p = 0.98) nor DNA-TG (p = 0.53) were significantly associated with the hazard of osteonecrosis in Cox models stratified by the three age groups and adjusted for sex.

CONCLUSION

Maintenance therapy intensity determined by 6MP and MTX metabolites was not associated with the risk of developing osteonecrosis in the NOPHO ALL2008 cohort.

Methotrexate polyglutamate quantification for clinical application in patients with pediatric acute lymphoblastic leukemia in association with genetic polymorphisms

We developed and validated a quantification method for methotrexate (MTX) polyglutamates (MTX-PGs, MTX-PG1 to MTX-PG5) by liquid chromatography-tandem mass spectrometry using stable isotope-labeled internal standards and applied to 196 clinical samples collected from pediatric acute lymphoblastic leukemia patients treated with MTX. MTX-PGs levels and their proportions (%) in sum of all MTX-PGs (MTXSum) were evaluated in relation to TPMT, NUDT15, and MTHFR genotypes. For the developed method, linearity ranges 1-500 nmol/L, bias for accuracy 0.3-13.5 %, coefficient of variation for within- and between-run imprecision of 3.2-9.5% and 1.5-12.0%, respectively. Recoveries achieved were 74.2-105.8 %. There was no significant carryover. The median level of the MTXSum for 196 clinical samples was 129.4 nmol/L (interquartile range 28.1-241.2). MTX dose and MTX-PGs were associated (P < 0.05) and among five MTX-PGs, MTX-PG3 was the predominant form (median 41.7 %). The MTX-PG3 level was significantly higher in patients with TPMT *1/*3C than in patients with wild type and MTX-PG3% was significantly higher and MTX-PG5% was significantly lower in NUDT15 intermediate metabolizers than normal or indeterminate phenotypes (P < 0.05). This validated MTX-PGs quantification method can facilitate a better understanding of MTX metabolism and therapeutic drug monitoring for MTX treatment.

Effects of germline DHFR and FPGS variants on methotrexate metabolism and relapse of leukemia

Methotrexate (MTX) during maintenance therapy is essential for curing acute lymphoblastic leukemia (ALL), but dosing strategies aiming at adequate treatment intensity are challenged by interindividual differences in drug disposition. To evaluate genetic factors associated with MTX metabolism, we performed a genome-wide association study in 447 ALL cases from the Nordic Society for Pediatric Haematology and Oncology ALL2008 study, validating results in an independent set of 196 patients. The intergenic single-nucleotide polymorphism rs1382539, located in a regulatory element of DHFR, was associated with increased levels of short-chain MTX polyglutamates (P = 1.1 × 10-8) related to suppression of enhancer activity, whereas rs35789560 in FPGS (p.R466C, P = 5.6 × 10-9) was associated with decreased levels of long-chain MTX polyglutamates through reduced catalytic activity. Furthermore, the FPGS variant was linked with increased relapse risk (P = .044). These findings show a genetic basis for interpatient variability in MTX response and could be used to improve future dosing algorithms.

Glutamic Acid Increased Methotrexate Polyglutamation and Cytotoxicity in a CCRF-SB Acute Lymphoblastic Leukemia Cell Line

Background and Objectives: Acute lymphoblastic leukemia (ALL) is the most common type of cancer in childhood. The majority of patients respond to treatment, but those with resistant phenotypes suffer relapse or death. The antifolate methotrexate (MTX) is the most commonly used drug against ALL due to its efficacy. Once inside leukemic cells, MTX is metabolized into methotrexate polyglutamates (MTX-PG) by action of the enzyme folylpolyglutamate synthetase (FPGS), leading to a longer action compared to that of MTX alone. Materials and Methods: In this work, we demonstrated that the combination treatment of methotrexate and 5 and 10 mM glutamic acid could enhance methotrexate cytotoxicity in CCRF-SB (B-ALL) cells. In addition, MTX plus 20 mM glutamic acid was able to improve the synthesis of MTX-PG₅. Results: All treatments induced an increase in FPGS expression compared to that of the control group. Furthermore, we detected different cellular expression patterns of FPGS in the different treatments. Conclusion: Based on these findings, we demonstrated that levels of methotrexate polyglutamates (MTX-PGs) could be a key determinant of methotrexate-induced cytotoxicity in CCRF-SB acute lymphoblastic leukemia cells.

Methotrexate Polyglutamate Values in Children and Adolescents With Acute Lymphoblastic Leukemia During Maintenance Therapy

Inadequate adherence to maintenance therapy is a major cause of relapse in patients with acute lymphoblastic leukemia (ALL). Therapeutic monitoring of mercaptopurine (thiopurine) red cell metabolites to assess adherence has been available for many years. Recently a clinical laboratory improvement amendments of 1988-approved test for methotrexate with three polyglutamate residues (MTXPG3) measured in peripheral blood red cells was approved. MTXPG3 is the primary intracellular metabolite of methotrexate, and like thiopurine metabolites, is retained for the life of the red cell giving an estimate of drug exposure over time. Normative values for MTXPG3 are available for adults and children with rheumatoid arthritis on methotrexate monotherapy, which are not applicable for patients with ALL on maintenance. Older literature on the MTXPG3 fraction in children with ALL is limited. We examined the MTXPG3 levels from 123 samples in 76 patients with ALL on maintenance oral methotrexate and mercaptopurine that were collected for clinical care. Male individuals had significantly higher MTXPG3 levels than female individuals which was unrelated to absolute neutrophil count, age, serum creatinine, and average doses of methotrexate or mercaptopurine. The MTXPG3 5th, 10th, 90th, and 95th percentile values are 0, 8.4, 53, and 64, respectively with a median of 24.7 nmol/L. The low 5th percentile MTXPG3 reflects 6 samples from 3 patients, age 16 to 21 years that were considered poorly adherent before collecting the specimen. As with red cell thiopurine (mercaptopurine) metabolites, MTXPG3 normative values may provide useful information to monitor for poor patient adherence or methotrexate toxicity during maintenance chemotherapy in ALL.