Identifying risk factors for high-dose methotrexate-induced toxicities in children with acute lymphoblastic leukemia

Risk factors associated with high-dose methotrexate induced toxicities

INTRODUCTION

High-dose methotrexate (HDMTX) therapy poses challenges in various neoplasms due to individualized pharmacokinetics and associated adverse effects. Our purpose is to identify early risk factors associated with HDMTX-induced toxicities, paving the way for personalized treatment.

AREAS COVERED

A systematic review of PubMed and Cochrane databases was conducted for articles from inception to July 2023. Eligible studies included reviews, clinical trials, and real-world analyses. Irrelevant studies were excluded, and manual searches and citation reviews were performed. Factors such as MTX exposure, drug interactions, demographics, serum albumin, urine pH, serum calcium, and genetic polymorphisms affecting MTX transport (e.g. SLCO1B1), intracellular folate metabolism (MTHFR), cell development (ARID5B), metabolic pathways (UGT1A1, PNPLA3), as well as epigenetics were identified.

EXPERT OPINION

This comprehensive review aids researchers and clinicians in early identification of HDMTX toxicity risk factors. By understanding the multifaceted risk factors associated with hematologic malignancies, personalized treatment approaches can be tailored to optimize therapeutic outcomes.

Involvement of the ABCB1 C3435T Variant but Not the MTHFR C677T or MTHFR A1298C Variant in High-Dose Methotrexate-Induced Toxicity in Pediatric Acute Lymphoblastic Leukemia Patients in China

Purpose

It remains unclear whether the MTHFR C677T, MTHFR A1298C and ABCB1 C3435T genetic variants are associated with methotrexate (MTX) elimination delay and high-dose MTX (HD-MTX) toxicities in the treatment of pediatric acute lymphoblastic leukemia (ALL). The aim of our study was to analyze the potential predictive role of MTHFR C677T, MTHFR A1298C and ABCB1 C3435T in toxicities and the relationship between these variants and MTX elimination delay during HD-MTX therapy in pediatric ALL patients.

Patients and Methods

We conducted a retrospective study on ALL patients receiving HD-MTX treatment with available MTHFR C677T, MTHFR A1298C and ABCB1 C3435T genotype and 44-h plasma MTX levels. Logistic regression analyses and chi-square tests were used to assess the relationship between the variants and HD-MTX toxicities and MTX elimination delay.

Results

Genotype frequencies were in Hardy-Weinberg equilibrium. MTX elimination delay did not significantly differ between MTHFR C677T and MTHFR A1298C or ABCB1 C3435T. Leukopenia (P=0.028), neutropenia (P=0.034) and oral mucositis (P=0.023) were 6.444-fold, 4.978-fold and 9.643-fold increased, respectively, in ABCB1 C3435T homozygous genotype (TT) patients compared to wild-type (CC) patients. No significant association was found between the toxicities investigated and MTHFR C677T or MTHFR A1298C.

Conclusion

This study showed that the ABCB1 C3435T homozygous allele genotype (TT) is associated with increased MTX-related toxicities (leukopenia, neutropenia and oral mucositis). These results may help to distinguish pediatric ALL patients with a relatively high risk of MTX-related toxicities before HD-MTX infusion and optimize MTX treatment.

Chemotherapy-related symptoms in children with leukemia: application of latent profile analysis and network analysis

PURPOSE

Children with leukemia may experience a range of chemotherapy-related symptoms. Identifying subgroups and their distinct characteristics of symptoms may improve symptom management. We aimed to identify subgroups and their distinct characteristics of chemotherapy-related symptoms in children with leukemia.

METHODS

A cross-sectional survey was conducted among 500 children with leukemia, who completed questionnaires that assessed their demographic and clinical characteristics, as well as the Memorial Symptom Assessment Scale. Latent profile analysis was conducted to identify subgroups of symptoms. Additionally, multiple regression analysis and network analysis were utilized to reveal the characteristics of each subgroup.

RESULTS

Four subgroups were identified: "Profile 1: low symptom burden subgroup" (26.2%), "Profile 2: moderate symptom burden subgroup in transitional period" (14.8%), "Profile 3: moderate psychological symptom burden subgroup" (35.6%), and "Profile 4: high symptom burden subgroup" (23.4%). Multiple logistic regression analysis indicated that lower primary caregiver's education level, lower family monthly income, self-paid medical expenses, induction remission period, and consolidation enhancement period were associated with more severe symptoms of subgroups. Network analysis further revealed that nausea was the core symptom in Profiles 1 and 2, while the core symptom in Profile 3 was "I don't look like myself." Additionally, worrying was the core symptom in Profile 4.

CONCLUSION

There exists heterogeneity in chemotherapy-related symptoms. Four subgroups and their corresponding characteristics of children with varying symptom severity were identified. Identifying these subgroups will facilitate personalized care, maximize intervention effectiveness, and alleviate symptom burden.

Early clinical indicators of acute kidney injury caused by administering high-dose methotrexate therapy to juvenile pigs

Introduction

Early identification of compromised renal clearance caused by high-dose methotrexate (HDMTX) is essential for initiating timely interventions that can reduce acute kidney injury and MTX-induced systemic toxicity.

Methods

We induced acute kidney injury (AKI) by infusing 42 juvenile pigs with 4 g/kg (80 g/m2) of MTX over 4 hours without high-volume alkalinizing hydration therapy. Concentrations of serum creatinine and MTX were measured at 15 time points up to 148 hours, with 10 samples collected during the first 24 hours after the start of the HDMTX infusion.

Results

During the first 28 hours, 81% of the pigs had increases in the concentrations of serum creatinine in one or more samples indicative of AKI (i.e., > 0.3g/dL increase). A rate of plasma MTX clearance of less than 90% during the initial 4 hours after the HDMTX infusion and a total serum creatinine increase at 6 and 8 hours after starting the infusion greater than 0.3 g/dL were predictive of AKI at 28 hours (p < 0.05 and p < 0.001, respectively). At conclusion of the infusion, pigs with a creatinine concentration more than 0.3 g/dL higher than baseline or serum MTX greater than 5,000 μmol/L had an increased risk of severe AKI.

Conclusions

Our findings suggest that serum samples collected at conclusion and shortly after HDMTX infusion can be used to predict impending AKI. The pig model can be used to identify biological, environmental, and iatrogenic risk factors for HDMTX-induced AKI and to evaluate interventions to preserve renal functions, minimize acute kidney injury, and reduce systemic toxicity.

Ethnic-specific predictors of neurotoxicity among patients with pediatric acute lymphoblastic leukemia after high-dose methotrexate

BACKGROUND

High-dose methotrexate (HD-MTX; 5000 mg/m2 ) is an important component of curative therapy in many treatment regimens for high-risk pediatric acute lymphoblastic leukemia (ALL). However, methotrexate therapy can result in dose-limiting neurotoxicity, which may disproportionately affect Latino children. This study evaluated risk factors for neurotoxicity after HD-MTX in an ethnically diverse population of patients with ALL.

METHODS

The authors retrospectively reviewed the medical records of patients who were diagnosed with ALL and treated with HD-MTX at Texas Children's Cancer Center (2010-2017). Methotrexate neurotoxicity was defined as a neurologic episode (e.g., seizures or stroke-like symptoms) occurring within 21 days of HD-MTX that resulted in methotrexate treatment modifications. Mixed effects multivariable logistic regression was used to estimate the odds ratio (OR) and corresponding 95% confidence interval (CI) for the association between clinical factors and neurotoxicity.

RESULTS

Overall, 351 patients (58.1% Latino) who received 1183 HD-MTX infusions were evaluated. Thirty-five patients (10%) experienced neurotoxicity, 71% of whom were Latino. After adjusting for clinical risk factors, the authors observed that serum creatinine elevations ≥50% of baseline were associated with a three-fold increased odds (OR, 3.32; 95% CI, 0.98-11.21; p = .05) for neurotoxicity compared with creatinine elevation <25%. Notably, predictors of neurotoxicity differed by ethnicity. Specifically, Latino children experienced a nearly six-fold increase in neurotoxicity odds (OR, 5.80; 95% CI, 1.39-24.17; p = .02) with serum creatinine elevation ≥50% compared with creatinine elevation <25%.

CONCLUSIONS

The current findings indicate that serum creatinine elevations ≥50% may be associated with an increased risk for neurotoxicity among Latino children with ALL and may identify potential candidates for therapeutic or supportive care interventions.

High-dose methotrexate-related pneumonitis in a child with acute lymphoblastic leukemia

INTRODUCTION

Methotrexate is administered through different routes to treat childhood acute lymphoblastic leukemia. Toxicities of low, intermediate, or high doses of methotrexate have been described in the literature. Methotrexate-induced or related pneumonitis is a rare complication that leads, in most cases, to discontinuing this drug.

CASE REPORT

We report a case of a 17-year-old female patient with newly diagnosed B-acute lymphoblastic leukemia who received a high-dose methotrexate on an induction course. Eight days after methotrexate infusion, she developed fever, dyspnea, hypoxemia, and dry cough. Chest computed tomography showed mosaic attenuation of lung parenchyma and bilateral interstitial infiltrate in favor of hypersensitivity pneumonitis with no evidence of bacterial or fungal infections.

MANAGEMENT AND OUTCOME

Methotrexate-related pneumonitis was diagnosed and corticosteroids were prescribed. Improvement of the symptomatology was noted within four days. Given the importance of methotrexate in the treatment of acute lymphoblastic leukemia, intrathecal methotrexate was administered without incident and high-dose methotrexate was re-introduced successfully two and a half months after the pneumonitis episode while using corticosteroids. According to Naranjo's algorithm, the reaction to the drug was found to be probable with a score of 6.

DISCUSSION

Methotrexate is the backbone of acute lymphoblastic leukemia treatment, but numerous adverse reactions have been published of which methotrexate pneumonitis can be fatal in some cases. In this case, we concluded that this drug can be successfully reintroduced after methotrexate-related pneumonitis.

Melissa Officinalis L. aqueous extract pretreatment decreases methotrexate-induced hepatotoxicity at lower dose and increases 99mTc-phytate liver uptake, as a probe of liver toxicity assessment, in rats

OBJECTIVE

Hepatotoxicity remains amongst the restricting factors of Methotrexate (MTX)-associated cancer therapy, especially in high doses of chemo-drugs or prolonged treatment. Due to the known protective effects of Melissa officinalis (M. officinalis), the aqueous extract of this plant was evaluated to ameliorate MTX-associated hepatotoxicity in rats.

METHODS

Adult female Wistar rats were received or not M. officinalis aqueous extract at doses of 100 mg/kg (for 14 and 24 consecutive days) and 2 g/kg (for 14 consecutive days) by gavage technique. MTX (20 mg/kg) was intraperitoneally injected on the 10th- and 20th-day post-M. officinalis treatment. 24 h after the last day of treatment, ^99mTc-phytate was intravenously injected through the tail of rats. Animals were killed at 20 min after radiocolloid injection, and vital tissues including the liver and spleen were isolated, weighed, and their radioactivity was counted. As well, ^99mTc-phytate scintigraphy and histopathology of the liver were performed for higher accuracy.

RESULT

A significant increase in liver radioactivity was detected in M. officinalis+MTX receiving groups compared with the MTX rats which were more robust at a dose of 100 mg/kg for 14 days. Also, a significant reduction in liver radioactivity was evident with M. officinalis extract at a dose of 2 g/kg for 14 days in comparison with the control group, this reduction was not significant at the lower dose of 100 mg/kg. Gamma scintigraphy and histopathological examinations confirmed the hepatoprotective effect of M. officinalis vs MTX-induced liver injury in rats.

CONCLUSION

In conclusion, we highlighted the liver uptake of ^99mTc-phytate as a valuable method for assessment of liver toxicity and addressed that M. officinalis pretreatment (100 mg/kg for 14 days) ameliorates the MTX-associated hepatotoxicity in rats; however, M. officinalis itself induces liver toxicity at higher doses.

Hypoalbuminemia and not undernutrition predicts high-dose methotrexate-induced nephrotoxicity in children with acute lymphoblastic leukemia in resource-constrained centers

BACKGROUND

The standard practice to mitigate high-dose methotrexate (HD-MTX)-induced nephrotoxicity (HMN) in acute lymphoblastic leukemia (ALL) is to monitor levels until serum MTX falls below a predefined threshold. It is not feasible in most resource-constrained centers. Literature on the various factors affecting HMN in these centers is limited, retrospective, and heterogeneous. Though hypoalbuminemia has been postulated as a risk factor for HMN, the relationship of undernutrition with HMN has not been studied.

PROCEDURE

This prospective observational study consecutively enrolled children < 12 years old with ALL receiving HD-MTX. Children with preexisting renal disease and exposed to nephrotoxic drugs two weeks preceding HD-MTX infusion were excluded. HD-MTX was administered over 24 hours (BFM-2009 protocol) with 12 hours of prehydration. Solitary MTX levels at 36 hours (MTX36) were outsourced, and 6-8 doses of leucovorin were given six-hourly. Hydration was continued till last dose of leucovorin. Various factors affecting HMN (rise in creatinine to 1.5 times baseline) were recorded: age, sex, type of ALL, risk group of ALL, first dose of MTX, dose of MTX, undernourishment, serum protein, and albumin along with C-reactive protein and MTX36 levels.

RESULTS

Forty-four children who received 150 HD-MTX cycles were analyzed. HMN was seen in 14% of cycles. On univariate analysis, undernourishment, MTX36 levels, hypoproteinemia, and hypoalbuminemia were significantly associated with HMN. On multivariate analysis, hypoalbuminemia and MTX36 levels significantly predicted the development of HMN with odds ratios of 4.71 and 1.45.

CONCLUSION

Hypoalbuminemia and solitary serum MTX levels predict HMN in centers where serial MTX level monitoring is not feasible.

Nomogram predicting leukopenia in osteosarcoma after high-dose methotrexate chemotherapy

Purpose: To explore the trends of plasma drug concentration changes after high-dose methotrexate (MTX) treatment of osteosarcoma (OS), analyse the risk factors for leukopenia (LP) after MTX treatment, and establish a LP prediction nomogram.

Methods: A total of 35 OS patients at Tianjin Medical University Cancer Institute and Hospital between 2017 and 2021 were collected (the construction cohort). Another 12 OS patients between 2019 and 2021 in P.A. Hertsen Moscow Oncology Research Center were involved (the external validation cohort). Peripheral venous blood MTX concentration (C_MTX) was monitored at 0h, 6h, 24h, 48h and 72h after MTX administration. The characteristics were collected: age, sex, body surface area, lesion site, pathological subtype, pathological fractures, American Joint Committee on Cancer (AJCC) clinical stage, MTX dose, tumour necrosis, Ki-67 index, erythrocyte count, haemoglobin count, white blood cell count, platelet count (PLT), alanine aminotransferase (ALT), aspartate aminotransferase (AST), bilirubin, albumin concentration, creatinine, alkaline phosphatase, and lactate dehydrogenase. Logistic regression analysis was used to determine the risk factors for LP occurrence. Significant factors were used to construct the prediction nomogram.

Results: A total of 128 MTX chemotherapy cycles from 35 OS patients were included. Female, Ki-67>20%, C_MTX>112μmol/L at 6h, PLT, and AST were risk factors for post-chemotherapy LP occurrence. The LP prediction nomogram was created and validated.

Conclusions: Female, C_MTX at 6h, Ki-67 index, AST and PLT before MTX treatment were risk factors for LP in OS patients who received MTX treatment. The established nomogram can guide personalized LP prediction in OS patients receiving MTX chemotherapy.

Is hypoalbuminemia a risk factor for high-dose methotrexate toxicity in children with acute lymphoblastic leukemia?

Background

Repeated high-dose methotrexate (HDMTX) is a critical component of contemporary childhood acute lymphoblastic leukemia (ALL) treatment regimens. Serum albumin is considered a carrier of methotrexate (MTX) in the blood. Hypoalbuminemia is not a rare finding in children with leukemia. This study aimed to investigate the relationship between pre-infusion serum albumin and possible HDMTX toxicities.

Methods

Thirty Egyptian children with ALL were consecutively enrolled in the study between May 2018 and July 2020. They were prospectively followed up while receiving HDMTX during the consolidation phase of the TOTAL study XV protocol. HDMTX was administered intravenously as a 24-h infusion every 2 weeks. Doses of 2.5 g/m2 were used for low-risk patients and 5 g/m2 for standard/high-risk patients. The Common Terminology Criteria for Adverse Events (V.4.03) was used to report the observed toxicities after HDMTX cycles. Plasma MTX levels were estimated at 24 h (MTX24) from the beginning of HDMTX infusion in the first consolidation cycle. Serum albumin level was determined before HDMTX administration, and pre-infusion hypoalbuminemia was defined when serum albumin was <3.5 g/dL.

Results

The patients’ age ranged from 2.3 to 13.3 years at diagnosis, and most of them had B cell ALL (86.7%). Overall, 120 HDMTX cycles were analyzed, equally distributed between low and standard/high risk. Grade 3–4 anemia, grades 3–4 thrombocytopenia, febrile neutropenia, and oral mucositis were significantly more frequent in HDMTX cycles with pre-infusion hypoalbuminemia than those with normal pre-infusion albumin (p=0.003, p=0.007, p=0.006, and p=0.001, respectively). In addition, pre-infusion hypoalbuminemia was significantly associated with additional hospitalization due to HDMTX toxicity (p=0.031). Most HDMTX toxicities were comparable irrespective of the MTX dose. Oral mucositis was more frequently encountered in the 2.5 g/m2 than the 5 g/m2 HDMTX cycles (46.7 vs. 26.7%, p=0.023). A significantly longer hospitalization (due to HDMTX toxicity) was observed in the 5 g/m2 HDMTX cycles (median= 7 days vs. 4 days, p=0.012).

Conclusions

Serum albumin levels should be checked before starting HDMTX cycles, especially in resource-limited settings where malnutrition is common, and serum MTX monitoring may not be available. Optimizing serum albumin levels before HDMTX may help decrease the possibility of HDMTX toxicities.

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.

Effects of piperacillin/tazobactam or cefepime on folinate dose in patients receiving high-dose methotrexate: A retrospective cohort study using Japanese administrative claims data

INTRODUCTION

Delayed methotrexate (MTX) clearance with the co-administration of piperacillin/tazobactam (PIPC/TAZ) has been reported. Penicillins have been associated with reduced MTX clearance but the evidence is limited. There are no cases described with cefepime but penicillins are listed as interacting with MTX. We aimed to reveal whether the co-administration of PIPC/TAZ or CFPM affects MTX clearance using data from an administrative database.

METHODS

We used data from the JMDC database, a large insurance claims database constructed in Japan. We included patients who were prescribed PIPC/TAZ or CFPM between days 1 and 3 in high-dose MTX (HD-MTX). We compared one co-administration episode (with PIPC/TAZ or CFPM) to one control episode (without), as a match-control study of two different episodes in the same patient. The primary outcomes were the duration and cumulative dose of leucovorin (LV) as a surrogate indicator of delayed MTX clearance.

RESULTS

Three patients who were co-administered PIPC/TAZ and 16 patients who were co-administered CFPM with HD-MTX were included. In the PIPC/TAZ group, the duration and the cumulative doses of LV were similar in co-administration and control episode (median 3.0 vs. 3.0 days and 288.0 vs. 219.0 mg). In the CFPM group, the duration and the cumulative doses of LV were not significantly different in co-administration and control episode (3.0 vs. 4.0 days and 169.5 vs. 258.0 mg).

CONCLUSIONS

Our findings revealed that PIPC/TAZ did not necessarily cause a delay in MTX clearance during HD-MTX therapy. Moreover, the co-administration of CFPM with HD-MTX did not affect MTX clearance.

Machine learning to predict high-dose methotrexate-related neutropenia and fever in children with B-cell acute lymphoblastic leukemia

Methotrexate (MTX), an antimetabolite for the treatment of leukemia, could cause neutropenia and subsequently fever, which might lead to treatment delay and affect prognosis. Here, we aimed to predict neutropenia and fever related to high-dose MTX using artificial intelligence. This study included 139 pediatric patients newly diagnosed with standard- or intermediate risk B-cell acute lymphoblastic leukemia. Fifty-seven SNPs of 16 genes were genotyped. Univariate and multivariate analysis were used to select SNPs and clinical covariates for model developing. Five machine learning algorithms combined with four resampling techniques were used to build optimal predictive model. The combination of random forest with adaptive synthetic appeared to be the best model for neutropenia (sensitivity = 0.935, specificity = 0.920, AUC = 0.927) and performed best for fever (sensitivity = 0.818, specificity = 0.924, AUC = 0.870). By machine learning, we have developed and validated comprehensive models to predict the risk of neutropenia and fever. Such models may be helpful for medical oncologists in quick decision-making.

Metabolic compensation activates pro-survival mTORC1 signaling upon 3-phosphoglycerate dehydrogenase inhibition in osteosarcoma

Osteosarcoma is the most common pediatric and adult primary malignant bone cancer. Curative regimens target the folate pathway, downstream of serine metabolism, with high-dose methotrexate. Here, the rate-limiting enzyme in the biosynthesis of serine from glucose, 3-phosphoglycerate dehydrogenase (PHGDH), is examined, and an inverse correlation between PHGDH expression and relapse-free and overall survival in osteosarcoma patients is found. PHGDH inhibition in osteosarcoma cell lines attenuated cellular proliferation without causing cell death, prompting a robust metabolic analysis to characterize pro-survival compensation. Using metabolomic and lipidomic profiling, cellular response to PHGDH inhibition is identified as accumulation of unsaturated lipids, branched chain amino acids, and methionine cycle intermediates, leading to activation of pro-survival mammalian target of rapamycin complex 1 (mTORC1) signaling. Increased mTORC1 activation sensitizes cells to mTORC1 pathway inhibition, resulting in significant, synergistic cell death in vitro and in vivo. Identifying a therapeutic combination for PHGDH-high cancers offers preclinical justification for a dual metabolism-based combination therapy for osteosarcoma.

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.

Association of ABCC2 with levels and toxicity of methotrexate in Malaysian Childhood Acute Lymphoblastic Leukemia (ALL)

Studies had shown that genetic polymorphism plays a significant role in the pharmacokinetics and pharmacodynamics variation of high dose methotrexate (MTX), 5000 mg/m² regimen. The objective of this study was to investigate the genetic variations associated with the serum level and toxicity of MTX in Malaysian children with acute lymphoblastic leukemia (ALL). Thirty-eight patients were genotyped for rs717620 (ABCC2), rs4948496 (ARID5B), rs1801133 (MTHFR) and rs4149056 (SLCO1B1). Serum levels of MTX at 48 h post 24 h of intravenous infusion were analyzed by high-performance liquid chromatography-mass spectrometry. The ABCC2 genotype was significantly associated with the serum levels of MTX at 48 h after treatment (p = 0.017). Patients with CT and TT of rs717620 (ABCC2) and TC and CC of rs4948496 (ARID5B) were significantly associated with leukopenia grade I-IV (Fisher Exact Test; p = 0.03 and 0.02, respectively). The three most common MTX related toxicities were leukopenia (60.5%), increased alanine aminotransferase enzyme (47.4%), and thrombocytopenia (47.4%). Our results demonstrate that by prescreening of patients for ABCC2 and ARID5B associated with the serum levels and adverse effects of MTX would identify patients at risk and therefore help a pediatric oncologist to personalize chemotherapy drugs for precision health.