Pretreatment Plasma Folate Modulates the Pharmacodynamic Effect of High-Dose Methotrexate in Children with Acute Lymphoblastic Leukemia and Non-Hodgkin Lymphoma: “Folate Overrescue” Concept Revisited

Effects of SLCO1B1 on elimination and toxicities of high-dose methotrexate in pediatric acute lymphoblastic leukemia

Aim: To evaluate the association between SLCO1B1 polymorphisms and elimination/toxicities of high-dose methotrexate (MTX). Methods: SLCO1B1 rs11045879 and rs4149056 polymorphisms were retrospectively genotyped in 301 children with newly diagnosed acute lymphoblastic leukemia. MTX concentration, doses of leucovorin rescue and toxicities were recorded. Results: SLCO1B1 rs11045879C carriers (CC + CT) had higher plasma MTX levels at 96 hr, and longer MTX elimination time. The number of leucovorin rescue doses in rs4149056C carriers (CC + CT) was more than those in TT ones. Moreover, SLCO1B1 polymorphisms were associated with HDMTX toxicities including thrombocytopenia, renal toxicity and anal mucositis, but not associated with MTX level at other time points or delayed elimination. Conclusions: Our data demonstrate that genotyping of SLCO1B1 might be useful to optimize MTX therapy.

Extracorporeal Treatment for Methotrexate Poisoning: Systematic Review and Recommendations from the EXTRIP Workgroup

Methotrexate is used in the treatment of many malignancies, rheumatological diseases, and inflammatory bowel disease. Toxicity from use is associated with severe morbidity and mortality. Rescue treatments include intravenous hydration, folinic acid, and, in some centers, glucarpidase. We conducted systematic reviews of the literature following published EXtracorporeal TReatments In Poisoning (EXTRIP) methods to determine the utility of extracorporeal treatments in the management of methotrexate toxicity. The quality of the evidence and the strength of recommendations (either "strong" or "weak/conditional") were graded according to the GRADE approach. A formal voting process using a modified Delphi method assessed the level of agreement between panelists on the final recommendations. A total of 92 articles met inclusion criteria. Toxicokinetic data were available on 90 patients (89 with impaired kidney function). Methotrexate was considered to be moderately dialyzable by intermittent hemodialysis. Data were available for clinical analysis on 109 patients (high-dose methotrexate [>0.5 g/m²]: 91 patients; low-dose [≤0.5 g/m²]: 18). Overall mortality in these publications was 19.5% and 26.7% in those with high-dose and low-dose methotrexate-related toxicity, respectively. Although one observational study reported lower mortality in patients treated with glucarpidase compared with those treated with hemodialysis, there were important limitations in the study. For patients with severe methotrexate toxicity receiving standard care, the EXTRIP workgroup: (1) suggested against extracorporeal treatments when glucarpidase is not administered; (2) recommended against extracorporeal treatments when glucarpidase is administered; and (3) recommended against extracorporeal treatments instead of administering glucarpidase. The quality of evidence for these recommendations was very low. Rationales for these recommendations included: (1) extracorporeal treatments mainly remove drugs in the intravascular compartment, whereas methotrexate rapidly distributes into cells; (2) extracorporeal treatments remove folinic acid; (3) in rare cases where fast removal of methotrexate is required, glucarpidase will outperform any extracorporeal treatment; and (4) extracorporeal treatments do not appear to reduce the incidence and magnitude of methotrexate toxicity.

Folinic acid rescue during methotrexate treatment for low-risk gestational trophoblastic neoplasia - How much is just right?

OBJECTIVE

To compare the outcomes of patients with low-risk gestational trophoblastic neoplasia (GTN) treated with 8-day methotrexate (MTX) with two different regimens of folinic acid (FA).

METHODS

Retrospective cohort study of low-risk GTN followed at Rio de Janeiro Federal University, from January/2000-December/2019 with 8-day MTX with FA at 0.1 mg/kg versus 15 mg fixed dose.

RESULTS

Among 667 patients with low-risk GTN, 323 were treated with FA at 0.1 mg/kg and 142 with FA at 15 mg fixed dose. The weight-based and fixed dose groups were comparable in terms of clinical profile but did differ in the hCG pretreatment level (8883 versus 5127 IU/L, p < 0.01) and FIGO risk score 5/6 (3.4% versus 18.3%, p < 0.01), respectively. Despite this, there was no difference in the remission rate in first-line treatment (76.8 versus 81%, p = 0.33), although FA at 0.1 mg/kg had a significantly higher number of chemotherapy cycles to remission (5 versus 4, p < 0.01), need to delay chemotherapy due to toxicity (6.8 versus 2.8%, p < 0.01) and time to remission, (12 versus 8 weeks, p < 0.01), respectively. A logistic regression analysis showed that the different FA rescue regimens appeared comparable in terms of achieving remission in first-line chemotherapy for low-risk GTN (OR:5.16, CI95%:0.84-31.64, p = 0.08).

CONCLUSION

FA with 15 mg fixed dose as compared to 0.1 mg/kg of FA was associated with similar primary remission rate, relapse or death among low-risk GTN treated with 8-day MTX. This regimen is highly practical, reduces visits to health facilities, appears equally safe and may be preferable with the 8-day MTX regimen in the treatment of low-risk GTN.

Reduced dose folinic acid rescue after rapid high-dose methotrexate clearance is not associated with increased toxicity in a pediatric cohort

Purpose

Low doses of folinic acid (FA) rescue after high-dose methotrexate (HD-MTX) have been associated with increased toxicity, whereas high doses may be related to a decreased antileukemic effect. The optimal dosage and duration of FA rescue remain controversial. This study was designed to investigate, whether a shorter duration of FA rescue in the setting of rapid HD-MTX clearance is associated with increased toxicity.

Methods

We reviewed the files of 44 children receiving a total of 350 HD-MTX courses during treatment for acute lymphoblastic leukemia according to the NOPHO ALL-2000 protocol. Following a 5 g/m2 HD-MTX infusion, pharmacokinetically guided FA rescue commenced at hour 42. As per local guidelines, the patients received only one or two 15 mg/m² doses of FA in the case of rapid MTX clearance (serum MTX ≤ 0.2 μmol/L at hour 42 or hour 48, respectively). Data on MTX clearance, FA dosing, inpatient time, and toxicities were collected.

Results

Rapid MTX clearance was observed in 181 courses (51.7%). There was no difference in the steady-state MTX concentration, nephrotoxicity, hepatotoxicity, neutropenic fever, or neurotoxicity between courses followed by rapid MTX clearance and those without. One or two doses of FA after rapid MTX clearance resulted in a 7.8-h shorter inpatient time than if a minimum of three doses of FA would have been given.

Conclusion

A pharmacokinetically guided FA rescue of one or two 15 mg/m² doses of FA following HD-MTX courses with rapid MTX clearance results in a shorter hospitalization without an increase in toxic effects.

Folate metabolism: a re-emerging therapeutic target in haematological cancers

Folate-mediated one carbon (1C) metabolism supports a series of processes that are essential for the cell. Through a number of interlinked reactions happening in the cytosol and mitochondria of the cell, folate metabolism contributes to de novo purine and thymidylate synthesis, to the methionine cycle and redox defence. Targeting the folate metabolism gave rise to modern chemotherapy, through the introduction of antifolates to treat paediatric leukaemia. Since then, antifolates, such as methotrexate and pralatrexate have been used to treat a series of blood cancers in clinic. However, traditional antifolates have many deleterious side effects in normal proliferating tissue, highlighting the urgent need for novel strategies to more selectively target 1C metabolism. Notably, mitochondrial 1C enzymes have been shown to be significantly upregulated in various cancers, making them attractive targets for the development of new chemotherapeutic agents. In this article, we present a detailed overview of folate-mediated 1C metabolism, its importance on cellular level and discuss how targeting folate metabolism has been exploited in blood cancers. Additionally, we explore possible therapeutic strategies that could overcome the limitations of traditional antifolates.

Risk factors for delayed elimination of high-dose methotrexate in childhood acute lymphoblastic leukemia and lymphoma

High-dose methotrexate (HD-MTX) therapy is widely used in patients with acute lymphoblastic leukemia (ALL) and lymphoma. However, some patients experience delayed MTX elimination, which requires treatment suspension or dose reduction to avoid organ damage. This single-center retrospective analysis reviewed the clinical data of 88 children with ALL or non-Hodgkin lymphoma who received a total of 269 courses of HD-MTX therapy between April 2008 and April 2019. HD-MTX was defined as MTX administration at 2.0, 3.0, or 5.0 g/m² over a 24-h period, and delayed MTX elimination was defined as a serum MTX concentration ≥ 1.0 µmol/L at 48 h after the start of HD-MTX. Clinical factors were compared between courses with and without delayed MTX elimination. MTX elimination was delayed in 21 of the 269 courses (7.8%). Multivariate analysis showed that first HD-MTX course (OR 4.04), lower urine volume per BSA on the first day of HD-MTX administration (< 2,675 mL/m², OR 5.10), higher total bilirubin (> 0.5 mg/dL, OR 5.11), lower eGFR (< 136 mL/min/1.73 m², OR 3.90), higher dose of MTX(> 3.0 g/m², OR 10.8), and lower urine volume per BSA on the next day of starting HD-MTX (< 2,107 mL/m², OR 3.43) were independent risk factors for delayed MTX elimination.

Folinic acid over rescue of high dose methotrexate: How problematic citations conserve discredited concepts

BACKGROUND

The outdated axiom that the dose of Folinic acid (FA) rescue used after high dose Methotrexate (HDMTX) should be kept to a minimum in order to prevent a reduction of prognosis ("over rescue") continues to be expressed even though the concept has been seriously challenged. Study aim The ways "problematic citations" are used to support an old theory, such as this, was examined.

RESULTS

Ten patterns of "problematic citation" use were identified. In 8 of these patterns the articles used were scientifically sound and the problem was with the articles citing them. However in 2 other pattens, the articles and their conclusions were flawed and citing them, apparently, resulted from accepting the presented data or conclusions as sound and valid. The patterns were 1. Claims based on data that are not present in the cited article. 2. Selective inclusion of data from cited articles. 3. Citation of misleading data presented only in the abstract. 4. Reporting trends as statistically significant. 5. Copying the citations used by others without checking the article. 6. Acceptance of illusionary truth in spite of knowledge to the contrary. 7. Citation of reports not relevant to the population under discussion 8. Presenting opinions as facts without any citation. 9. Selective presentation of data sets that support the thesis while ignoring the data sets that show the opposite results. 10. Use of a title expressing what the authors intended to show but not what was found.

IMPLICATIONS

The containing acceptance of this old insupportable conjecture, in part, because of "problematic citations" has resulted in unnecessary neurocognitive damage to patients and may have resulted in the misconception that it is the outcome of HDMTX that may have lead to its abandonment in favour of more toxic therapies. Realisation that this is a significant problem in data analysis should lead authors and reviewers to be even more carefully in checking all references. The importance of high-quality reviews is clearly evident. The effect of "Canonization of false facts" is a serious impairment to the acceptance of new hypotheses that better express reality and could lead to improved treatment results. Authors are advised only to cite articles they have read in entirety not relying on the title, abstract or previous use and to check the content of citations before submission.

The evaluation of red blood cell folate and methotrexate levels during protocol M in childhood acute lymphoblastic leukemia

BACKGROUND

After High-Dose Methotrexate (HD-MTX), folinic acid rescue therapy (Leucovorin) is administered to reduce side effects in pediatric acute lymphoblastic leukemia (ALL) patients. Leucovorin and MTX are structural analogues, possibly competing for cellular transport and intracellular metabolism. We hypothesize that Leucovorin accumulates during consecutive courses, which might result in a lower MTX uptake.

METHODS

We prospectively measured red blood cell (RBC) folate and MTX levels during four HD-MTX and Leucovorin courses in 43 patients treated according the DCOG ALL-11 protocol with 2-weekly HD-MTX (5 g/m²/dose) and Leucovorin (15 mg/m²/dose) using LC-MS/MS. We estimated a linear mixed model to assess the relationship between these variables over time.

RESULTS

Both RBC MTX-PG and folate levels increased significantly during protocol M. MTX-PG_2-5 levels increased most substantially after the first two HD-MTX courses (until median 113.0 nmol/L, IQR 76.8-165.2) after which levels plateaued during the 3^d and 4th course (until median 141.3 nmol/L, IQR 100.2-190.2). In parallel, folate levels increased most substantially after the first two HD-MTX courses (until median 401.6 nmol/L, IQR 163.3-594.2) after which levels plateaued during the 3^d and 4th course (until median 411.5 nmol/L, IQR 240.3-665.6). The ratio folate/MTX-PG decreased significantly over time, which was mostly due to the relatively higher increase (delta) of MTX-PG.

CONCLUSION

These results suggest that the increase in RBC folate levels does not seem to have a large effect on RBC MTX levels. Future studies, assessing competition of Leucovorin and MTX on other cellular mechanisms which might negatively affect treatment efficacy, are necessary.

A prospective, crossover randomized trial of the optimal timing for leucovorin rescue after high-dose methotrexate management in adult non-Hodgkin's lymphoma patients

This study aimed to investigate the optimal time of leucovorin rescue for HDMTX in non-Hodgkin's lymphoma (NHL) patients. Ninety-eight patients treated with HDMTX were randomly assigned to receive leucovorin at either 18 or 24 h after initiation of HDMTX infusion during the first cycle and switched to the other mode in the second cycle. All courses achieved an efficacious MTX concentration. Compared to the 18th hour group, the 24th hour group exhibited an increase in incidence of thrombocytopenia (48% versus 34.7%, p = .036) and grade III/IV neutropenia (34.7% versus 21.4%, p = .039). No bleeding occurred and the incidence of fever with grade III/IV neutropenia was low with no difference observed between the two groups. We recommend that with the HDMTX generally used most adult patients with NHL may have greater therapeutic benefit and acceptable toxicity with their LV rescue started at 24 h instead of 18 h.

Patient-derived oral mucosa organoids as an in vitro model for methotrexate induced toxicity in pediatric acute lymphoblastic leukemia

We have recently established a protocol to grow wildtype human oral mucosa organoids. These three-dimensional structures can be maintained in culture long-term, do not require immortalization, and recapitulate the multilayered composition of the epithelial lining of the oral mucosa. Here, we validate the use of this model to study the effect of Leucovorin (LV) on Methotrexate (MTX)-induced toxicity. MTX is a chemotherapeutic agent used in the treatment of pediatric acute lymphoblastic leukemia. Although effective, the use of MTX often results in severe side-effects, including oral mucositis, which is characterized by epithelial cell death. Here, we show that organoids are sensitive to MTX, and that the addition of LV reduces MTX toxicity, in both a concentration- and timing-dependent manner. Additionally, we show that a 24 hour ‘pretreatment’ with LV reduces MTX-induced cell death, suggesting that such a pretreatment could decrease mucositis in patients. Taken together, we provide the first in vitro model to study the effect of MTX on wildtype oral mucosa cells. Our findings underscore the relevance of the clinically applied LV regimen and highlight the potential of this model to further optimize modifications in dosing and timing of Leucovorin on oral mucosa cells.

Dose Issues in Cancer Chemotherapy

In this review, human methotrexate dosing regimens, as well as their relationship to data from in vitro cell culture and in vivo animal and human studies, are discussed. Low-dose, intermediate-dose, and high-dose therapies are covered. Since in vitro and in vivo screenings of potential cancer drugs are commonplace in the development of cancer chemotherapy, comparisons of the three criteria for effectiveness are important.

Leucovorin ameliorated methotrexate induced intestinal toxicity via modulation of the gut microbiota

Methotrexate (MTX) is a widely used therapeutic agent for the treatment of cancer and autoimmune diseases. However, its efficacy is often limited by adverse effects, such as intestinal toxicity. Although treatment with leucovorin (LV) is the most common method to reduce the toxic effects of MTX, it may also compromise the therapeutic effects of MTX. The gut microbiome has been reported to be associated with the intestinal toxicity of MTX. In this study, the intestinal damage of MTX was ameliorated by treatment with LV. Moreover, the population, diversity, and principal components of the gut microbiota in MTX-treated mice were restored by treatment with LV. The only element of the gut microbiota that was significantly changed after treatment with LV was Bifidobacterium, and supplementation with Bifidobacterium longum ameliorated MTX-induced intestinal damage. In conclusion, our results suggest that the balance and the composition of gut microbiota have an important role in the LV-mediated protection against MTX-induced intestinal toxicity. This work provides foundation of data in support of a new potential mechanism for the prevention of MTX-induced intestinal toxicity.

Changes in intracellular folate metabolism during high-dose methotrexate and Leucovorin rescue therapy in children with acute lymphoblastic leukemia

Background

Methotrexate (MTX) is an important anti-folate agent in pediatric acute lymphoblastic leukemia (ALL) treatment. Folinic acid rescue therapy (Leucovorin) is administered after MTX to reduce toxicity. Previous studies hypothesized that Leucovorin could ‘rescue’ both normal healthy cells and leukemic blasts from cell death. We assessed whether Leucovorin is able to restore red blood cell folate levels after MTX.

Methods

We prospectively determined erythrocyte folate levels (5-methyltetrahydrofolate (THF) and non-methyl THF) and serum folate levels in 67 children with ALL before start (T0) and after stop (T1) of HD-MTX and Leucovorin courses.

Results

Erythrocyte folate levels increased between T0 and T1 (mean ± SD: 416.7 ± 145.5 nmol/L and 641.2 ± 196.3 nmol/L respectively, p<0.001). This was due to an increase in 5-methyl THF levels (mean increase: 217.7 ± 209.5 nmol/L, p<0.001), whereas non-methyl THF levels did not change (median increase: 0.6 nmol/L [-9.9–11.1], p = 0.676). Serum folate levels increased between T0 and T1 (median increase: 29.2 nmol/L [32.9–74.0], p<0.001). Results were not significantly affected by age, sex, ALL immunophenotype and MTHFR c.677C>T genotype.

Conclusion

Intracellular folate levels accumulate after HD-MTX and Leucovorin therapy in children with ALL, suggesting that Leucovorin restores the intracellular folate pool. Future studies are necessary to assess concomitant lower uptake of MTX.

Disparities in Neurotoxicity Risk and Outcomes among Pediatric Acute Lymphoblastic Leukemia Patients

Purpose: Methotrexate chemotherapy can be associated with neurologic complications during therapy and long-term neurologic deficits. This study evaluated demographic and clinical factors associated with incidence of methotrexate neurotoxicity and described the impact of neurotoxicity on acute lymphoblastic leukemia (ALL) therapy in pediatric patients.Experimental Design: Patients were enrolled between 2012 and 2017 from three pediatric cancer treatment centers in the United States. Medical records for suspected cases of methotrexate neurotoxicity, defined as an acute neurologic event following methotrexate therapy, were reviewed. Cox proportional hazards models were used to estimate the association between race/ethnicity and methotrexate neurotoxicity. Multivariable linear regression models compared treatment outcomes between patients with and without methotrexate neurotoxicity.Results: Of the 280 newly diagnosed patients enrolled, 39 patients (13.9%) experienced methotrexate neurotoxicity. Compared with non-Hispanic whites, Hispanic patients experienced the greatest risk of methotrexate neurotoxicity (adjusted HR, 2.43; 95% CI, 1.06-5.58) after accounting for sex, age at diagnosis, BMI Z-score at diagnosis, and ALL risk stratification. Patients who experienced a neurotoxic event received an average of 2.25 fewer doses of intrathecal methotrexate. Six of the 39 cases of neurotoxicity (15.4%) experienced relapse during the study period, compared with 13 of the 241 (2.1%) patients without neurotoxicity (P = 0.0038).Conclusions: Hispanic ethnicity was associated with increased risk of methotrexate neurotoxicity, which was associated with treatment modifications and relapse. Understanding the mechanism and predictors of methotrexate neurotoxicity is important to improving treatment outcomes in pediatric ALL. Clin Cancer Res; 24(20); 5012-7. ©2018 AACR.

Consensus Guideline for Use of Glucarpidase in Patients with High-Dose Methotrexate Induced Acute Kidney Injury and Delayed Methotrexate Clearance

An expert panel was convened to provide specific, expert consensus guidelines for the use of glucarpidase in patients who develop high‐dose methotrexate (HDMTX)‐induced nephrotoxicity and delayed methotrexate excretion. This guideline provides recommendations to identify the population of patients who would benefit from glucarpidase rescue by more precisely defining the absolute methotrexate concentrations associated with risk for severe or life‐threatening toxicity at several time points after the start of a HDMTX infusion.

Acute kidney injury due to high‐dose methotrexate (HDMTX) is a serious, life‐threatening toxicity that can occur in pediatric and adult patients. Glucarpidase is a treatment approved by the Food and Drug Administration for high methotrexate concentrations in the context of kidney dysfunction, but the guidelines for when to use it are unclear. An expert panel was convened to provide specific, expert consensus guidelines for the use of glucarpidase in patients who develop HDMTX‐induced nephrotoxicity and delayed methotrexate excretion. The guideline provides recommendations to identify the population of patients who would benefit from glucarpidase rescue by more precisely defining the absolute methotrexate concentrations associated with risk for severe or life‐threatening toxicity at several time points after the start of an HDMTX infusion. For an HDMTX infusion ≤24 hours, if the 36‐hour concentration is above 30 µM, 42‐hour concentration is above 10 µM, or 48‐hour concentration is above 5 µM and the serum creatinine is significantly elevated relative to the baseline measurement (indicative of HDMTX‐induced acute kidney injury), glucarpidase may be indicated. After a 36‐ to 42‐hour HDMTX infusion, glucarpidase may be indicated when the 48‐hour methotrexate concentration is above 5 µM. Administration of glucarpidase should optimally occur within 48–60 hours from the start of the HDMTX infusion, because life‐threatening toxicities may not be preventable beyond this time point.

Implications for Practice.

Glucarpidase is a rarely used medication that is less effective when given after more than 60 hours of exposure to high‐dose methotrexate, so predicting early which patients will need it is imperative. There are no currently available consensus guidelines for the use of this medication. The indication on the label does not give specific methotrexate concentrations above which it should be used. An international group of experts was convened to develop a consensus guideline that was specific and evidence‐based to identify the population of patients who would benefit from glucarpidase.

Dorsal column myelopathy after intrathecal chemotherapy for leukemia

Intrathecal chemotherapy with methotrexate, a folate antagonist, is widely used to treat central nervous system malignancies. The mechanisms underlying methotrexate-induced neurotoxicity are unclear but may be related to increased homocysteine levels. Intrathecal methotrexate-induced myelopathy mimicking subacute combined degeneration, with normal B12 levels, has been documented. We examined treatment and magnetic resonance imaging (MRI) characteristics of 13 patients with leukemia who received intrathecal methotrexate and developed urinary and bowel incontinence, ascending motor weakness, and sensory loss with dorsal column hyperintensity on MRI between 2000 and 2016. Cerebrospinal fluid evaluation was negative for leukemia in all patients and positive for elevated protein in 12 patients. Seven of eight patients with available data had reduced serum folate, increased serum homocysteine, or both, implicating methotrexate as the cause of neurotoxicity. Autopsy of one patient revealed loss of myelinated axons in the posterior columns. These findings suggest that methotrexate neurotoxicity may be mediated by folate antagonism. Awareness and a high index of suspicion of these characteristic clinical and radiographic features in patients who develop myelopathy after intrathecal methotrexate may help to avoid additional neurotoxic therapy in such patients.

Much more than you expected: The non-DHFR-mediated effects of methotrexate

BACKGROUND

For decades, methotrexate (MTX; amethopterin) has been known as an antifolate inhibitor of dihydrofolate reductase (DHFR), and it is widely used for the treatment of various malignancies and autoimmune diseases. Although the inclusion of MTX in various therapeutic regimens is based on its ability to inhibit DHFR and consequently to suppress the synthesis of pyrimidine and purine precursors, recent studies have shown that MTX is also able to target other intracellular pathways that are independent of folate metabolism.

SCOPE OF REVIEW

The main aim of this review is to summarize the most important, up-to-date findings of studies regarding the non-DHFR-mediated mechanisms of MTX action.

MAJOR CONCLUSIONS

The effectiveness of MTX is undoubtedly caused by its capability to affect various intracellular pathways at many levels. Although the most important therapeutic mechanism of MTX is strongly based on the inhibition of DHFR, many other effects of this compound have been described and new studies bring new insights into the pharmacology of MTX every year.

GENERAL SIGNIFICANCE

Identification of these new targets for MTX is especially important for a better understanding of MTX action in new protocols of combination therapy.

The frequency of hepatotoxicity and myelotoxicity in leukemic children with different high doses of methotrexate

Background and objectives

Methotrexate (MTX) is a chemotherapeutic agent that functions as a folic acid antagonist. The frequency of high dose methotrexate (HDMTX)-associated toxicity is variable. In this study, we investigated the frequency of myelotoxicity and hepatotoxicity 7 days after HDMTX infusion.

Patients and methods

This study included children diagnosed with acute lymphoblastic leukemia (ALL) between January 2010 and April 2015. The patient blood counts and biochemical parameters measured before and after 7 days of HDMTX infusion were retrospectively recorded. We assessed HDMTX infusions for 48 children. The number of patients and drug doses included the following: 17 children receiving 1 g/m² (68 infusions), 14 children receiving 2 g/m² (56 infusions), and 17 children receiving 5 g/m² (68 infusions). The classification of toxicity was made based on the Common Terminology Criteria for Adverse Events (CTCAE) 2010 criteria. Myelotoxicity was defined as a hemoglobin level <10 g/L and absolute neutrophil count <1 × 10⁹/L or platelet count <75 × 10⁹/L. The presence of transaminase levels ≥5 times the upper limit was considered to be hepatotoxicity grade ≥3. The MTX levels at 42 h in patients with and without toxicity were compared to evaluate the correlation between MTX levels, hematologic parameters, and transaminase levels.

Results

Myelotoxicity was observed in 35.2%, 37.5%, and 33.8% of the infusions, and hepatotoxicity grade ≥3 was detected in 13.2%, 12.5%, and 11.7% of the infusions in patients receiving 1, 2 and 5 g/m² HDMTX after 7 days, respectively. There was no statistically significant difference between MTX levels at 42 h in patients with and without toxicity (P > .05, for all). There was no correlation between hematologic parameters and transaminase levels and MTX levels at 42 h.

Conclusion

Hematologic toxicity was the most common toxicity observed. The data indicate the hematologic toxicity increased after repeated cycles in patients receiving 5 g/m². However, the hepatic toxicity decreased with additional cycles. Our results show the level of MTX at 42 h is not effective to identify toxicity.

Non-DHFR-mediated effects of methotrexate in osteosarcoma cell lines: epigenetic alterations and enhanced cell differentiation

Background

Methotrexate is an important chemotherapeutic drug widely known as an inhibitor of dihydrofolate reductase (DHFR) which inhibits the reduction of folic acid. DHFR-mediated effects are apparently responsible for its primary antineoplastic action. However, other non-DHFR-mediated effects of methotrexate have been recently discovered, which might be very useful in the development of new strategies for the treatment of pediatric malignancies. The principal goal of this study was to analyze the possible impact of clinically achievable methotrexate levels on cell proliferation, mechanisms of epigenetic regulation (DNA methylation and histone acetylation), induced differentiation and the expression of differentiation-related genes in six osteosarcoma cell lines.

Methods

The Saos-2 reference cell line and five other patient-derived osteosarcoma cell lines were chosen for this study. The MTT assay was used to assess cell proliferation, DNA methylation and histone acetylation were detected using ELISA, and western blotting was used for a detailed analysis of histone acetylation. The expression of differentiation-related genes was quantified using RT-qPCR and the course of cell differentiation was evaluated using Alizarin Red S staining, which detects the level of extracellular matrix mineralization.

Results

Methotrexate significantly decreased the proliferation of Saos-2 cells exclusively, suggesting that this reference cell line was sensitive to the DHFR-mediated effects of methotrexate. In contrast, other results indicated non-DHFR-mediated effects in patient-derived cell lines. Methotrexate-induced DNA demethylation was detected in almost all of them; methotrexate was able to lower the level of 5-methylcytosine in treated cells, and this effect was similar to the effect of 5-aza-2′-deoxycytidine. Furthermore, methotrexate increased the level of acetylated histone H3 in the OSA-06 cell line. Methotrexate also enhanced all-trans retinoic acid-induced cell differentiation in three patient-derived osteosarcoma cell lines, and the modulation of expression of the differentiation-related genes was also shown.

Conclusions

Overall non-DHFR-mediated effects of methotrexate were detected in the patient-derived osteosarcoma cell lines. Methotrexate acts as an epigenetic modifier and has a potential impact on cell differentiation and the expression of related genes. Furthermore, the combination of methotrexate and all-trans retinoic acid can be effective as a differentiation therapy for osteosarcoma.

DHFR-mediated effects of methotrexate in medulloblastoma and osteosarcoma cells: the same outcome of treatment with different doses in sensitive cell lines

Although methotrexate (MTX) is the most well-known antifolate included in many standard therapeutic regimens, substantial toxicity limits its wider use, particularly in pediatric oncology. Our study focused on a detailed analysis of MTX effects in cell lines derived from two types of pediatric solid tumors: medulloblastoma and osteosarcoma. The main aim of this study was to analyze the effects of treatment with MTX at concentrations comparable to MTX plasma levels in patients treated with high-dose or low-dose MTX. The results showed that treatment with MTX significantly decreased proliferation activity, inhibited the cell cycle at S-phase and induced apoptosis in Daoy and Saos-2 reference cell lines, which were found to be MTX-sensitive. Furthermore, no difference in these effects was observed following treatment with various doses of MTX ranging from 1 to 40 μM. These findings suggest the possibility of achieving the same outcome with the application of low-dose MTX, an extremely important result, particularly for clinical practice. Another important aspect of treatment with high-dose MTX in clinical practice is the administration of leucovorin (LV) as an antidote to reduce MTX toxicity in normal cells. For this reason, the combined application of MTX and LV was also included in our experiments; however, this application of MTX together with LV did not elicit any detectable effect. The expression analysis of genes involved in the mechanisms of resistance to MTX was a final component of our study, and the results helped us to elucidate the mechanisms of the various responses to MTX among the cell lines included in our study.

Statistical analysis of relation between plasma methotrexate concentration and toxicity in high-dose methotrexate therapy of childhood nonHodgkin lymphoma

BACKGROUND

Plasma monitoring of Methotrexate (MTX) levels is a standard approach to predict MTX-related toxicities in a high-dose (HD) MTX monotherapy for childhood acute lymphoblastic leukemia. However, it is uncertain whether plasma MTX levels can predict MTX-related toxicity in the HDMTX plus additional chemotherapy for childhood B-cell nonHodgkin lymphoma (B-NHL).

PROCEDURES

To statistically analyze the relationship between MTX pharmacokinetic parameters and MTX-related toxicities, we collected data from patients with delayed MTX elimination (≥1 µM at 48 hr and/or ≥0.5 µM at 72 hr) in the Japanese Pediatric Leukemia/Lymphoma Study Group (JPLSG) BNHL 03 study. Blood MTX levels were measured at 24, 48, and 72 hr after 3 or 5 g/m² HD-MTX administration for 24 hr.

RESULTS

Three hundred and four patients received 2-4 courses of the HDMTX plus additional chemotherapy, and delayed MTX elimination was observed in 165 courses of 127 patients. In those, nephrotoxicity was significantly correlated with plasma MTX levels for each patient (P = 0.03), and also for each course (P = 0.009), but no other toxicities were correlated. Another analysis according to HDMTX courses showed no significant correlation between the first high plasma MTX levels and subsequent MTX levels in later course. It also showed that incidence of liver and gastrointestinal toxicities was most frequent in the first HDMTX course, and then sharply decreased in later courses (P < 0.001).

CONCLUSIONS

Our results suggest that plasma MTX level is not a reliable predictor for adverse events except for nephrotoxicity in multiple HDMTX therapy courses in childhood B-NHL. Pediatr Blood Cancer 2015;62:279-284. © 2014 Wiley Periodicals, Inc.

Impact of SLCO1B1 521T > C variant on leucovorin rescue and risk of relapse in childhood acute lymphoblastic leukemia treated with high-dose methotrexate

BACKGROUND

Recent studies suggest that SLCO1B1 c.521T > C variant decreases the clearance of methotrexate (MTX) and elevates its plasma concentration, hence leucovorin doses may need to be adjusted. However, high leucovorin doses may affect the cure rate in childhood acute lymphoblastic leukemia (ALL). Hitherto neither the appropriate dose of leucovorin in carriers of SLCO1B1 c.521T > C variant nor the impact of SLCO1B1 polymorphism on the risk of ALL relapse has been clarified.

PROCEDURE

A double-blind and controlled study was conducted in 136 children with ALL. They were genotyped for rs4149056 single nucleotide polymorphism into wild-type group and variant group, and received MTX at 3-5 g/m(2) . Plasma concentration MTX and its metabolite were determined by HPLC. The toxicity of MTX, dose of leucovorin and 5-year relapse rate of ALL were recorded.

RESULTS

Compared with wild-type group, area under the concentration time curve of MTX increased by 4.2-fold and peripheral clearance rate decreased significantly in variant group. Patients carrying rs4149056 C allele endured a remarkable longer time above the MTX safety threshold and suffered from a higher frequency of toxicity, so 2.2-fold leucovorin was given. However, no association was found between SLCO1B1 c.521T > C variant and the relapse risk in five years.

CONCLUSIONS

The SLCO1B1 c.521T > C variant was an important determinant of MTX disposition and their carriers were exposed to increased intensity and time of MTX. An appropriate leucovorin dose raise in variant group was beneficial to reducing the serious toxicity. The c.521T > C variant wasn't associated with the risk of ALL relapse.

Genetic and metabolic determinants of methotrexate-induced mucositis in pediatric acute lymphoblastic leukemia

Methotrexate (MTX) is an effective and toxic chemotherapeutic drug in the treatment of pediatric acute lymphoblastic leukemia(ALL). In this prospective study, we aimed to identify metabolic and genetic determinants of MTX toxicity. One hundred and thirty-four Dutch pediatric ALL patients were treated with four high infusions MTX (HD-MTX: 5 g m(-2)) every other week according to the DCOG-ALL-10 protocol. Mucositis (National Cancer Institute grade ⩾ 3) was the most frequent occurring toxicity during the HD-MTX phase (20%) and occurred especially after the first MTX course. Mucositis was not associated with plasma MTX, plasma folate or plasma homocysteine levels. Patients with mucositis had higher erythrocyte folate levels at the start of protocol M than patients without mucositis (median 1.4 vs 1.2 μmol l(-1), P<0.008), this could reflect an increased MTX uptake in mucosal cells of patients with mucositis. From 17 single-nucleotide polymorphisms in the MTX pathway, only patients with the wild-type variant of rs7317112 SNP in the ABCC4 gene had more mucositis (AA (39%) vs AG/GG (15%), P=0.016). We found no evidence that erythrocyte folate levels mediate in the association between the rs7317112 and mucositis.

Challenging the clinical relevance of folinic acid over rescue after high dose methotrexate (HDMTX)

THE HYPOTHESIS

The use of adequate folinic acid rescue (in clinically relevant doses) after high dose methotrexate will prevent neurotoxicity without reducing treatment results.

METHODS

A literature search was performed to test the hypothesis that no evidence for the existence of folinic acid over-rescue of high-dose methotrexate (MTX) in clinically relevant situations exists (evidence that too much folinic acid reduced cure rate).

EMPIRICAL DATA

Examples of folinic acid over-rescue after lower doses of MTX were found and has been cited as evidence of over rescue of high dose MTX. Mega doses of folinic acid, used when toxic levels of MTX occurred, also could neutralize the MTX effect. Data were found to support the contention that higher levels of MTX require disproportionally higher folinic acid doses for rescue. Careful examination of the available studies after HDMTX yielded more convincing alternative explanations for reduction in cure rate than over rescue. Little convincing evidence for the existence of over rescue after HDMTX was found.

DISCUSSION

The rescue of high-dose MTX with an appropriate dose of folinic acid that can prevent toxicity, especially neurotoxicity, was not shown to reduce the therapeutic effect. No evidence was found that higher doses of folinic acid after high dose MTX reduces the therapeutic effect.

CONSEQUENCES OF THE HYPOTHESIS

Acceptance of the hypothesis can prevent harm being caused (especially brain damage) by reversing the trend of dose reduction in FA rescue. The recognition that the use of higher folinic acid doses is safe, can prevent neurotoxicity, and does not reduce prognosis has important implications for the development of effective non toxic treatment protocols.

Comparison of pharmacokinetics and toxicity after high-dose methotrexate treatments in children with acute lymphoblastic leukemia

We carried out a detailed comparative study of the pharmacokinetics and toxicity of methotrexate (MTX) and 7-hydroxy-methotrexate (7-OH-MTX) after high-dose intravenous methotrexate (HD-MTX) in children with acute lymphoblastic leukemia (ALL). Overall, 65 children were treated with 5 g/m2/24 h MTX and 88 children were treated with 2 g/m2/24 h MTX according to ALL-BFM 95 and ALL IC-BFM 2002 protocols (mean age: 6.4 years, range 1.0-17.9 years). A total of 583 HD-MTX courses were analyzed. Serum MTX and 7-OH-MTX levels were measured at 24, 36, and 48 h, and cerebrospinal fluid (CSF) MTX levels were determined 24 h after the initiation of the infusion. The area under the concentration-time curve was calculated. Hepatotoxicity, nephrotoxicity, and bone marrow toxicity were estimated by routine laboratory tests. We investigated pharmacokinetics and toxicity in distinct age groups (< 6 and > 14 years). 5 g/m2/24 h treatments resulted in higher serum and CSF MTX and 7-OH-MTX levels (P < 0.05). The CSF penetration rate of MTX was independent of the MTX dose [2.3% (95% confidence interval: 1.7-2.5%) vs. 2.8% (95% confidence interval: 2.4-3%)]. The CSF MTX concentration was correlated with the 24 h MTX serum level (r = 0.38, P < 0.0001). Repeated treatments did not alter MTX or 7-OH-MTX levels. 7-OH-MTX levels were correlated with nephrotoxicity (r = 0.36, P < 0.0001). Higher MTX levels and toxicity occurred more frequently in children aged older than 14 years (P < 0.05). Therapeutic serum and CSF MTX concentrations can be achieved more reliably with 5 g/m2/24 h treatments. To predict the development of toxicity, monitoring of the level of the 7-OH-MTX is useful. Monitoring of pharmacokinetics is essential to prevent the development of severe adverse events in adolescents.

Plasma methotrexate, red blood cell methotrexate, and red blood cell folate values and outcome in children with precursor B-acute lymphoblastic leukemia: a report from the Children's Oncology Group

Plasma steady state methotrexate (MTX) level and red blood cell (RBC) MTX and folate concentrations were evaluated in 1124 children with newly diagnosed acute lymphoblastic leukemia enrolled in the Pediatric Oncology Group studies 9005 (lower risk; Regimens A and C) and 9006 (higher risk; Regimen A). These regimens included intermediate-dose MTX (1 g/m) given as a 24 hours infusion every other week for 12 doses during intensification. Plasma MTX level was evaluated at the end of MTX infusions. RBC MTX and folate concentrations were measured at the end of intensification. The 5 year continuous complete remission was 76±1.4% versus 85±3.0% for those patients with steady state MTX levels less than or equal to and greater than 14 μM, respectively (P=0.0125). Hispanic children had significantly reduced median steady state MTX levels, 8.7 μM, compared with non-Hispanic children, 9.95 μM (P=0.0015), but this did not correlate with a difference in outcome. Neither RBC MTX, RBC folate, nor the RBC MTX:folate ratio identified children at increased risk of failure.

High dose methotrexate chemotherapy: pharmacokinetics, folate and toxicity in osteosarcoma patients

AIMS

To investigate the relationships between pretreatment folate concentrations, MTX pharmacokinetics and acute toxicities following high dose methotrexate (HD MTX) therapy.

METHODS

MTX and its major extracellular metabolite 7-OH-MTX were measured in eight serum samples per HD MTX cycle in 65 consecutive osteosarcoma patients (288 cycles) and AUC (area under the blood concentration-time curve) was calculated. Pretreatment concentrations of folate in serum (S) and erythrocytes (ER) were determined. Hepatic, renal and haematological toxicities, assessed by routine laboratory parameters, as well as mucositis were graded according to National Cancer Institute Common Terminology Criteria for adverse events (CTCAE v.3.0). Dermatitis and pleuritis were reported as occurred or not.

RESULTS

S- and ER-folate pretreatment concentrations increased significantly with increasing number of HD MTX cycles (P < 0.001). ER-folate pretreatment concentrations were higher among males (median 610 nmol l⁻¹, 95% CI 550, 680) compared with females (median 465 nmol l⁻¹, 95% CI 430, 520, P < 0.001), but showed no correlation with MTX or 7-OH-MTX pharmacokinetics. We found correlations between alanine aminotransferase peak concentration (ALAT(max) ) and clearance of MTX (P < 0.001), gender (P < 0.001), age (P < 0.001) and 7-OH-MTX concentrations (P < 0.001), the latter being the main factor influencing ALAT(max) .

CONCLUSION

Our results suggest that 7-OH-MTX is involved in the development of HD MTX hepatic toxicity and that young female patients are most affected.

Folate fortification and survival of children with acute lymphoblastic leukemia

BACKGROUND

The antifolate drug methotrexate is a mainstay of treatment for children diagnosed with acute lymphoblastic leukemia (ALL). There have been concerns regarding the impact of folate fortification on the efficacy of methotrexate therapy and hence treatment outcomes of ALL.

OBJECTIVE

The objective of this study was to evaluate whether folate fortification has been associated with a higher incidence of adverse outcomes in children with ALL.

METHODS

In a retrospective, population-based study, using data from the Pediatric Oncology Group of Ontario (POGO), Ontario, Canada, and the WHO, we examined yearly and population-adjusted mortality rates in Canada, the US, and several European countries.

RESULTS

Our analysis demonstrates that there has been a decreasing trend in ALL mortality numbers and rates between 1999 and 2005 in the US and Canada, in a similar degree to those in European countries where folate fortification is not implemented.

CONCLUSION

These data suggest that folate fortification does not appear to have caused an increase in therapeutic failures in children with ALL.

Protective effects of amifostine and cyclooxygenase-1 inhibitor against normal human epidermal keratinocyte toxicity induced by methotrexate and 5-fluorouracil

Our study aimed to find more effective protective agents against mucosa toxicity induced by methotrexate and 5-fluorouracil. We focused on the relationship between oral mucositis and keratinocyte injury and examined methotrexate and 5-fluorouracil-induced cytotoxicity in normal human epidermal keratinocyte cell lines. Cell viability and superoxide radical activity were measured based on converting WST-1 (4-[3-(4-indophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzen disulfonate) to a water-soluble formazan dye. DNA synthesis by 5-bromo-2'-deoxyuridine incorporation was measured as an indirect parameter of cell proliferation. Allopurinol and amifostine were used as the radical scavengers. l-glutamine was used as a mucosa-protective agent. A cyclooxygenase inhibitor interrupting the production of hydroxyl radicals in the arachidonic acid cascade was also examined. 5-fluorouracil and methotrexate caused cytotoxicity due to the activation of intracellular superoxide radicals specifically on normal human epidermal keratinocytes. From the electron spin resonance study, it was found that allopurinol was a superoxide radical scavenger, while amifostine was hydroxyl radical scavenger. Allopurinol showed no effect on the cytotoxicity due to 5-fluorouracil and methotrexate. The cell injury induced by methotrexate was restored by amifostine. However, the cell injury induced by 5-fluorouracil was markedly recovered by a selective cyclooxygenase-1 inhibitor compared to amifostine. It was suggested that amifostine and cyclooxygenase-1 inhibitor could be useful protective agents against methotrexate and 5-fluorouracil chemotherapeutic toxicity. Additionally, this in vitro cell injury model using normal human epidermal keratinocytes may be useful for understanding the pathophysiology of oral mucositis induced by chemotherapeutic agents.

Pharmacogenetics of the neurodevelopmental impact of anticancer chemotherapy

Pharmacogenetics holds the promise of minimizing adverse neurodevelopmental outcomes of cancer patients by identifying patients at risk, enabling the individualization of treatment and the planning of close follow-up and early remediation. This review focuses first on methotrexate, a drug often implicated in neurotoxicity, especially when used in combination with brain irradiation. The second focus is on glucocorticoids that have been found to be linked to adverse developmental effects in relation with the psychosocial environment. For both examples, we review how polymorphisms of genes encoding enzymes involved in specific mechanisms of action could moderate adverse neurodevelopmental consequences, eventually through common final pathways such as oxidative stress. We discuss a multiple hit model and possible strategies required to rise to the challenge of this integrative research.

Retrospective study on elimination delay of methotrexate in high-dose therapy of childhood acute lymphoblastic leukemia in China

OBJECTIVES

The aim of this study was to observe the morbidity of elimination delay in Chinese children with acute lymphoblastic leukemia during high-dose methotrexate (HDMTX) therapy and the toxicities.

PATIENTS AND METHODS

A total of 121 children with acute lymphoblastic leukemia on HDMTX therapy were enrolled into this study. Patients were divided into groups on the basis of either dosage (3 g/m vs. 5 g/m) or infusion duration (7 h vs. 24 h). CF/MTX index was used to determine the calcium folinate (CF) rescuing intensity and toxicity was evaluated according to World Health Organization criteria.

RESULTS

The overall morbidity of elimination delay was 12.1% in a total of 497 infusions. Patients with elimination delay had lower platelet count (P<0.01) and greater cumulative CF rescuing intensity (P<0.001). In 3-g group, children with elimination delay experienced severer oral mucous membrane damage (P<0.05) than those without elimination delay, and postponement of following chemotherapy (P=0.001). No significant difference was found in morbidity of elimination delay between 3 and 5-g groups (P>0.05) or 7 and 24-hour infusion groups (P>0.05). The only raised adverse effect in 5-g group was gastrointestinal (P=0.003) as compared with 3-g group. The CF rescuing intensity of 5-g group without elimination delay was lower than that of the 3-g group (P<0.01).

CONCLUSIONS

(1) HDMTX with 5 g/m is as safe as 3 g/m under adequate hydration and alkalization. Twenty-four-hour infusion is optimal. (2) Individualized dosing is necessary.

[Case-control study evaluating the incidence of hyperhomocysteinemia in cancer patients in an internal medicine department]

PURPOSE

Cancer is a cause of venous thromboembolism. However, the physiopathology remains unknown. Hyperhomocysteinemia could be a promoting factor.

METHOD

We built a case-control study of 65 patients followed for 2 years to compare levels of homocystéinémie in cancer bearing patients with that in matched cancer free control patients.

RESULTS

Fifty per cent of cancer bearing patients had significantly increased blood serum levels of homocystéine (P=0.006). This increase did not correlate with any deficiency in blood serum levels of folate or vitamin B12.

CONCLUSION

High levels of homocystéinémie could be linked to tumor proliferation.

High leucovorin doses during high-dose methotrexate treatment may reduce the cure rate in childhood acute lymphoblastic leukemia

We explored the relationship between time to relapse and different exposure variables (serum methotrexate (S-MTX) 23, 36 and 42 h after start of administration, MTX elimination time and leucovorin (LV) dose) during high-dose MTX (HDM) treatment of 445 children with acute lymphoblastic leukemia. MTX was infused at 5 g/m2 (non-high risk) or 8 g/m2 (high risk) over 24 h, 2-9 times per patient. LV rescue dose was adjusted according to the S-MTX concentration. Time from end of the last HDM to relapse was analyzed by Cox regression analysis with the logarithms of S-MTX and LV dose as exposures. The combined results from all risk groups suggest that high LV dose is related to higher risk for relapse. Doubling of the LV dose increased the relapse risk by 22% (95% confidence interval 1-49%, P = 0.037). High LV doses correlated with high MTX levels at 23, 36 and 42 h and longer elimination time. The results suggest that high doses of LV increase the risk for relapse despite the fact that they were correlated with high MTX levels and longer MTX elimination time. The choice of MTX and LV doses may be regarded as an intricate balance between effect and counter-effect.