High-dose methotrexate (HDMTX) is a cornerstone of contemporary treatment protocols for both pediatric and adult acute lymphoblastic leukemia (ALL); however, up to 4% of children and 15% of adults develop renal toxicity with severely delayed MTX elimination (DME). Evidence-based guidance on re-exposure after DME is lacking, and omission of further HDMTX may compromise anti-leukemic efficacy and potentially increase the risk of relapse. This study, conducted within the Ponte di Legno International Toxicity Working Group, aimed to evaluate the safety of HDMTX re-challenge in pediatric patients after DME. National investigators from 12 countries provided case-level data on initial DME events and subsequent HDMTX re-exposures via structured questionnaires. Data from 189 patients treated for ALL who experienced DME were analyzed, of whom 143 were subsequently re-exposed to HDMTX. Clinical toxicities after the initial DME included gastrointestinal complications (vomiting, diarrhea, mucositis), infections, and neurological events (encephalopathy, seizures, MTX stroke-like syndrome). Laboratory toxicities comprised cytopenias and hepatic abnormalities. Two patients transiently required dialysis. DME led to chemotherapy modifications in 73% of the patients. After re-exposure, toxicities were similar in spectrum, self-limited, and non-fatal. Twenty children (14%) developed recurrent DME, including three with two additional episodes. Recurrent DME could neither be predicted by clinical, pharmacokinetic, or demographic variables, nor by uniform MTX dose reduction during re-exposure. In conclusion, re-exposure to HDMTX following DME is feasible and generally well tolerated, although the risk of recurrence is increased. Re-challenge should be considered once renal function has normalized, with careful monitoring and individualized dose adjustment.

High-dose methotrexate (HDMTX) is a cornerstone in pediatric oncology, but delayed methotrexate elimination (DME) can cause severe toxicity. Rescue therapy typically combines folinic acid (FA) and glucarpidase (GP), yet current guidelines recommend pausing FA around GP administration due to presumed interference. This study aimed to determine whether FA affects GP efficacy in metabolizing methotrexate and to assess the impact on folate metabolites. An ex vivo model was developed using human plasma spiked with clinically relevant concentrations of methotrexate and FA, with or without GP. Samples were analyzed by mass spectrometry to quantify methotrexate, FA, and related metabolites. Additional experiments included blood from pediatric patients receiving HDMTX per ALLTogether protocol. GP rapidly metabolized > 99

Treatment regimens for childhood acute lymphoblastic leukemia have developed steadily over the last decades, significantly improving patient outcomes. This has been achieved mainly by intensifying therapy, which also increased the risk of associated toxicity. To address this issue, therapeutic drug monitoring (TDM) has been introduced in clinical research and, for certain chemotherapeutic agents, as standard of care in protocols like the ALLTogether1. The goal of TDM is to optimize delivery of a given cytotoxic drug, while minimizing the risk of toxicity. Notwithstanding, only a subset of drugs included in the backbone of ALL treatment will be eligible for TDM, since specific pharmacokinetic and pharmacodynamic properties need to apply. Despite the recent rise of innovative therapies like immunotherapy, cytotoxic drugs remain a core component of ALL treatment, making the application of TDM crucial for improving patient outcomes. Among these chemotherapeutic agents, we focus on the monitoring of asparaginase, high-dose methotrexate, 6-mercaptopurine and low dose methotrexate in maintenance therapy, tyrosine kinase inhibitors and busulfan, in order to enhance clinical effectiveness. This narrative review further explains how TDM for these drugs should be conducted and offers practical recommendations for managing them in childhood ALL treatment. Moreover, ongoing research in TDM will allow for more personalized therapy delivery in frontline strategies, while optimizing care with lesser toxicity burden for patients.

Folinic acid (FA) rescue protocols to counter the adverse effects of high-dose methotrexate (HDMTX) vary widely, and the risk of over-rescue and potential adverse effects of excessive FA (e.g., hypercalcemia) are under-recognized issues when providing augmented rescue in cases of delayed methotrexate elimination (DME). This opinion summary defines over-rescue, describes its potential adverse impacts, highlights the risk of hypercalcemia associated with excessive FA dosing in patients with acute kidney injury (AKI) from HDMTX, and provides recommendations to improve safety and efficacy of FA rescue in patients receiving HDMTX. A multidisciplinary panel of experts with clinical experience in HDMTX treatment convened in three roundtable meetings to coalesce expert opinion and best published evidence on the pharmacology and clinical effects and interactions of FA and HDMTX. The type of FA (calcium folinate, calcium levofolinate, sodium levofolinate), dose, and frequency of FA administration may be factors for over-rescue and the development of hypercalcemia due to their respective pharmacokinetic characteristics, especially in cases of DME requiring augmented FA rescue. Clinicians are reminded of the possibility of over-rescue with FA and its impact on subsequent HDMTX courses, types of FA available and their durations of action, and avoid providing too frequent doses. In the setting of AKI and DME requiring high doses of FA, use of sodium levofolinate or calcium levofolinate may be considered to reduce the risk of hypercalcemia associated with calcium folinate.

High-dose methotrexate (HDMTX) therapy is an important component in treatment regimens for acute lymphoblastic leukemia (ALL). Courses are associated with a risk of renal injury, delayed elimination, and increased systemic toxicity. Recently hypoalbuminemia has been recognized as yet another risk factor. To examine the impact of serum albumin we reviewed 325 HDMTX 5 g/m2 courses in a cohort of 51 children treated on the NOPHO ALL 2008 protocol, dividing the courses into four groups with different levels of baseline albumin (A < 25 g/L, B 25–29 g/L, C 30–34 g/L and D ≥ 35 g/L). Hypoalbuminemia was present in 51

Aims High‐dose methotrexate (HDMTX) is an essential part of the treatment of several adult and paediatric malignancies. Despite meticulous supportive care during HDMTX administration, severe toxicities, including acute kidney injury (AKI), may occur contributing to patient morbidity. Population pharmacokinetics provide a powerful tool to predict time to clear HDMTX and adjust subsequent doses. We sought to develop and validate pharmacokinetic models for HDMTX in adults with diverse malignancies and to relate systemic exposure with the occurrence of severe toxicity. Methods Anonymized, de‐identified data were provided from 101 US oncology practices that participate in the Guardian Research Network, a non‐profit clinical research consortium. Modelled variables included clinical, laboratory, demographic and pharmacological data. Population pharmacokinetic analysis was performed by means of nonlinear mixed effects modelling using MonolixSuite. Results A total of 693 HDMTX courses from 243 adults were analysed, of which 62 courses (8.8%) were associated with stage 2/3 acute kidney injury (43 stage 2, 19 stage 3). A three‐compartment model adequately fitted the data. Time‐dependent serum creatinine, baseline serum albumin and allometrically scaled bodyweight were clinically significant covariates related to methotrexate clearance. External evaluation confirmed a satisfactory predictive performance of the model in adults receiving HDMTX. Dose‐normalized methotrexate concentration at 24 and 48 hours correlated with AKI incidence. Conclusion We developed a population pharmacometric model that considers weight, albumin and time‐dependent creatinine that can be used to guide supportive care in adult patients with delayed HDMTX elimination.

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.

High-dose methotrexate (HDMTX) is a central component in the treatment of acute lymphoblastic leukemia, osteosarcoma, and some lymphomas and brain tumors. MTX is given at lethal doses and then is followed by rescue treatment with folinic acid (FA). Despite FA rescue, many patients suffer severe toxicity. The pharmacokinetics of FA rescue have not been sufficiently studied. However, optimization of FA rescue could potentially increase anti-tumor effects, whilst decreasing organ toxicity. Here, we describe our efforts to establish and optimize a liquid chromatography tandem mass spectrometric (LC-MS/MS) method for the simultaneous determination of five essential components of the folate cycle, as well as MTX and its two metabolites. The method was applied to 6 individual patients receiving HDMTX, with 3 or 4 measurements for each patient. The method allows analysis of samples that were initially frozen. This notion, together with the test results in the 6 pilot patients, shows the feasibility of this method to study MTX and FA pharmacokinetics during HDMTX treatment. The method has the potential to optimize HDMTX and FA rescue treatment in individual patients.

Methotrexate (MTX), an anti-folate, is administered at high-doses to treat malignancies in children and adults. However, there is considerable interpatient variability in clearance of high-dose (HD) MTX. Patients with delayed clearance are at an increased risk for severe nephrotoxicity and life-threatening systemic MTX exposure. Glucarpidase is a rescue agent for severe MTX toxicity that reduces plasma MTX levels via hydrolysis of MTX into inactive metabolites, but is only indicated when MTX concentrations are > 2 standard deviations above the mean excretion curve specific for the given dose together with a significant creatinine increase (> 50%). Appropriate administration of glucarpidase is challenging due to the ambiguity in the labeled indication. A recent consensus guideline was published with an algorithm to provide clarity in when to administer glucarpidase, yet clinical interpretation of lab results that do not directly correspond to the algorithm prove to be a limitation of its use. The goal of our study was to develop a clinical decision support tool to optimize the administration of glucarpidase for patients receiving HD MTX. Here, we describe the development of a novel three-compartment MTX population PK model using 31,672 MTX plasma concentrations from 772 pediatric patients receiving HD MTX for the treatment of acute lymphoblastic leukemia and its integration into the online clinical decision support tool, MTXPK.org . This web-based tool has the functionality to utilize individualized demographics, serum creatinine, and real-time drug concentrations to predict the elimination profile and facilitate model-informed administration of glucarpidase.

Severely delayed elimination of methotrexate (MTX) is difficult to predict in patients treated with high‐dose MTX (HD‐MTX), but it may cause life‐threatening toxicity. It has not been defined how an increase in plasma creatinine can be best used as a predictor for severely delayed MTX elimination, thus providing a guide for therapeutic interventions to minimize renal toxicity.

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.

Trisomy 8 (+8) is a common cytogenetic aberration in acute myeloid leukemia (AML); however, the impact of +8 in pediatric AML is largely unknown. We retrospectively investigated 609 patients from the NOPHO‐AML database to determine the clinical and cytogenetic characteristics of +8 in pediatric AML and to investigate its prognostic impact. Complete cytogenetic data were available in 596 patients (98%) aged 0–18 years, diagnosed from 1993 to 2012, and treated according to the NOPHO‐AML 1993 and 2004 protocols in the Nordic countries and Hong Kong. We identified 86 patients (14%) with +8. Trisomy 8 was combined with other cytogenetic aberrations in 68 patients (11%) (+8 other) and in 18 patients (3%), it was the sole abnormality (+8 alone). Trisomy 8 was associated with FAB M5 (36%) but otherwise clinically comparable with non‐trisomy 8 patients. Trisomy 8 was favorable in patients of young age and with t(9;11). Trisomy 8 alone was associated with older age (median age 10.1 years), FAB M2 (33%), and FLT3‐ITD mutations (58%). The 5‐year event‐free survival for patients with +8 alone was 50% and 5‐year overall survival was 75%. In conclusion, +8 is one of the most common cytogenetic aberrations in pediatric AML. Trisomy 8 positive AML is a heterogeneous group and the majority of cases have additional cytogenetic aberrations. Patients with +8 alone differed from patients with +8 other and were associated with older age, FAB M2, and FLT3‐ITD aberrations. There were no differences in survival despite the more frequent occurrence of FLT3‐ITD in +8 alone. © 2016 Wiley Periodicals, Inc.

We investigated efficacy and toxicity of replacing conventional triple (cytarabine, methotrexate, and hydrocortisone) intrathecal therapy (TIT) with liposomal cytarabine during maintenance therapy among 40 acute lymphoblastic leukemia patients. Twenty-eight of 29 patients in the TIT arm received TIT and 9/11 in the liposomal cytarabine arm received liposomal cytarabine. Arachnoiditis occurred in all initial 5 patients given liposomal cytarabine and intrathecal prednisolone succinate. Subsequently liposomal cytarabine was given with systemic dexamethasone. Neurotoxicity occurred at 6/27 liposomal cytarabine administrations with concomitant dexamethasone (22%). More liposomal cytarabine-treated patients experienced neurotoxicity in relation to intrathecal therapy during at least 1 cycle compared with TIT-treated patients (6/9 [67%] vs. 3/28 [11%], P=0.002). Apart from intermittent lower extremity sensory pain in 1 liposomal cytarabine-treated patient, no permanent adverse neurological sequelae were observed. In intention-to-treat analysis, projected 5-year event-free survival (pEFS-5y) was borderline higher for patients in the liposomal cytarabine arm compared with the TIT arm (1.0 vs. 0.69, P=0.046). However, pEFS-5y and projected 5-year relapse-free survival did not differ signficantly between patients treated with liposomal cytarabine or TIT (1.0 vs. 0.73, P=0.10; 1.0 vs. 0.76, P=0.12). Larger prospective trials are needed to explore whether liposomal cytarabine should be used as first-line prevention of relapse.

BACKGROUND:Carboxypeptidase G2 (CPDG2 ) can be used as rescue treatment in cases of delayed methotrexate elimination (DME) and Mtx-induced nephrotoxicity. PROCEDURE:Between July 2008 and December 2014, all children (1.0-17.9 years) in the Nordic countries diagnosed with Philadelphia chromosome negative acute lymphoblastic leukemia (ALL) were treated according to the Nordic Organization for Pediatric Hematology and Oncology (NOPHO) ALL 2008 protocol, including administration of six to eight high-dose (5 g/m2 /24 hr) Mtx (HDMtx) courses. The protocol includes recommendations for CPDG2 administration in cases of DME (clinicaltrials.gov NCT01305655). RESULTS:Forty-seven of the 1,286 children (3.6%) received CPDG2 during 50 HDMtx courses at a median dose of 50 IU/kg. In 49% of the cases, CPDG2 was used during the first HDMtx course. Within a median of 6 hr from CPDG2 administration, the Mtx concentration decreased by 75% when measured with immune-based methods, and by 100% when measured with high-performance liquid chromatography. The median time from the start of Mtx infusion to plasma levels ≤ 0.2 μM was 228 hr (range: 48-438). The maximum increase in plasma creatinine was 375% (range: 100-1,310). Creatinine peaked after a median of 48 hr (range: 36-86). Mtx elimination time was shorter in patients with body surface area < 1 m2 (median 198.5 vs. 257 hr; P = 0.004) and was inversely correlated to the maximum creatinine increase (209 vs. 258 hr; P = 0.034). All patients normalized their renal function as measured with s-creatinine. CONCLUSIONS:CPDG2 administration is highly effective as rescue in case of delayed Mtx clearance. Subsequent HDMtx courses could be administered without events in most of the patients.

BackgroundStudies on adolescents and young adults with acute lymphoblastic leukemia suggest better results when using pediatric protocols for adult patients, while corresponding data for acute myeloid leukemia (AML) are limited.ProcedureWe investigated disease characteristics and outcome for de novo AML patients 10–30 years old treated in pediatric or adult departments. We included 166 patients 10–18 years of age with AML treated according to the pediatric NOPHO‐protocols (1993–2009) compared with 253 patients aged 15–30 years treated in hematology departments (1996–2009) in the Nordic countries.ResultsThe incidence of AML was 4.9/million/year for the age group 10–14 years, 6.5 for 15–18 years, and 6.9 for 19–30 years. Acute promyelocytic leukemia (APL) was more frequent in adults and in females of all ages. Pediatric patients with APL had similar overall survival as pediatric patients without APL. Overall survival at 5 years was 60% (52–68%) for pediatric patients compared to 65% (58–70%) for adult patients. Cytogenetics and presenting white blood cell count were the only independent prognostic factors for overall survival. Age was not an independent prognostic factor.ConclusionsNo difference was found in outcome for AML patients age 10–30 years treated according to pediatric as compared to adult protocols. Pediatr Blood Cancer 2015; 9999:1–10 © 2015 Wiley Periodicals, Inc.

Anna Andersson, Tanja Gruber, James Downing and colleagues report a genomic analysis of infant acute lymphoblastic leukemias with MLL rearrangements. They identify recurrent activating mutations in tyrosine kinase, phosphatidylinositol 3-kinase and RAS pathway genes but find that these mutations were often present in minor subclones and lost at the time of relapse. Infant acute lymphoblastic leukemia (ALL) with MLL rearrangements (MLL-R) represents a distinct leukemia with a poor prognosis. To define its mutational landscape, we performed whole-genome, exome, RNA and targeted DNA sequencing on 65 infants (47 MLL-R and 18 non–MLL-R cases) and 20 older children (MLL-R cases) with leukemia. Our data show that infant MLL-R ALL has one of the lowest frequencies of somatic mutations of any sequenced cancer, with the predominant leukemic clone carrying a mean of 1.3 non-silent mutations. Despite this paucity of mutations, we detected activating mutations in kinase-PI3K-RAS signaling pathway components in 47% of cases. Surprisingly, these mutations were often subclonal and were frequently lost at relapse. In contrast to infant cases, MLL-R leukemia in older children had more somatic mutations (mean of 6.5 mutations/case versus 1.3 mutations/case, P = 7.15 × 10−5) and had frequent mutations (45%) in epigenetic regulators, a category of genes that, with the exception of MLL, was rarely mutated in infant MLL-R ALL.

The World Health Organization (WHO) classification of myeloid leukaemia was revised in 2008. It incorporates newly recognized entities and emphasizes the pivotal role of cytogenetic abnormalities. The aim of this study was to evaluate the usability of the WHO classification when applied to a large population-based paediatric acute myeloid leukaemia (AML) cohort. We included children diagnosed with de novo AML, 0-18 years of age from the Nordic countries and Hong Kong from 1993 to 2012. Data were retrieved from the Nordic Society for Paediatric Haematology and Oncology AML database and patients classified according to the WHO 2008 classification. A successful karyotype was available in 97% of the cases. AML with recurrent genetic abnormalities were present in 262 (41%) and 94 (15%) were classified as AML with myelodysplasia-related changes (AML-MDS). WHO classifies patients with monosomy 7 and del(7q) into one group. We found that -7 (n = 14) had significantly poorer outcome than del(7q) (n = 11); 5-year event-free survival 26% vs. 67%, (P = 0·02), and 5-year overall survival 51% vs. 90%, (P = 0·04). The largest group was the highly heterogeneous AML not otherwise specified (NOS) (n = 280) (44%). In conclusion, the WHO classification allocated 15% to AML-MDS, 44% to NOS and grouped together entities with clearly different outcome, therefore limiting the applicability of the current WHO classification in children with AML.