High-dose Methotrexate Clearance Research Articles

Early Post-Infusion Clearance of High-Dose Methotrexate Predicts Delayed Methotrexate Elimination and Acute Kidney Injury

Introduction High-dose methotrexate (HDMTX) is used for the treatment of hematologic malignancies but its use may be limited by delayed methotrexate elimination and acute kidney injury (AKI). Current guidelines for glucarpidase recommend administration between 48-60 hours following the start of a 24-hour HDMTX infusion based on methotrexate concentration at 36-, 42-, or 48-hours [Ramsey 2016]. However, this may be too late to prevent permanent toxicities in cases where significant AKI develops early during infusion. Recent evidence from pig models have shown that early methotrexate measurements can predict the development of AKI [Buddington 2023]. The aim of this study is to determine whether early elimination of methotrexate (soon after completion of the infusion) is a useful “early clearance biomarker” of delayed methotrexate elimination and AKI in humans. Methods Retrospective data from two sites in Spain that collected two or more early measurements of methotrexate levels from the end of HDMTX infusion were analyzed from a larger HDMTX registry. Methotrexate half-life was calculated employing exponential decay equations and the slope of a line connecting two out of three early time points; each combination was tested, and the best performing pair is reported. Early levels were tagged according to visual exploration and k-means cluster analysis (Figure 1). Delayed methotrexate elimination was defined as a concentration above 1 μmol/L after 42-hours from the start of infusion (micromolar criterion) or above 2 standard deviations (SD) from the population mean modeled using MTXPK.org at 42- or 48-hours from the start of infusion (SD criterion). Receiver operating characteristic (ROC) curves were fitted, with their respective area under the curve (AUC) and confidence intervals for delayed methotrexate elimination and AKI. Additionally, a logistic regression model was employed to predict AKI using a base model with covariates (age, sex, HDMTX dose, and first course) plus early methotrexate clearance. Results Data from 144 patients who received 453 HDMTX courses were included. Patient characteristics were as follows: 41% females, age ranged from 1.2 to 81.5 years at the time of HDMTX infusion; diagnoses included acute lymphoblastic leukemia, 79%; non-Hodgkin lymphoma, 21%. Median methotrexate dose was 4,856.9 mg/m 2 [IQR 2,871.7 - 4,985.0], with 88% of the courses infused over 24 hours and 12% over 4 hours. Delayed methotrexate elimination was found in 41% and 6.6% of the courses according to the micromolar criterion and SD criterion, respectively. AKI developed in 29.6% of courses. Median time for the first, second and third measurements were 0.25 [IQR 0.00 - 0.71], 6.32 [IQR 5.86 - 6.69] and 12 [IQR 11.68 - 12.50] hours, respectively. Half-life estimation between the second and third early time-points predicted delayed methotrexate elimination by the micromolar criterion with an ROC AUC of 0.81 [CI95 0.76 - 0.87] or SD criterion with an ROC AUC of 0.84 [CI95 0.68 - 1.00] (Fig. 2) and any grade AKI with an ROC AUC of 0.62 [CI95 0.55 - 0.69]. After adjusting for age, sex, HDMTX dose, and first course, half-life remained statistically significant in the logistic regression model, with an odds ratio of 1.4 [CI95 1.1 - 1.8] (p < 0.01). The addition of half-life to the base model improved the overall performance (ANOVA, p < 0.01). Conclusions The half-life of methotrexate elimination soon after completing the HDMTX infusion defines an early clearance biomarker that predicts delayed methotrexate elimination and AKI. It requires only the measurement of 2 early methotrexate levels soon after completing the infusion, and thus represents a practical and applicable method to identify patients at risk who may need pre-emptive interventions like increased hydration or glucarpidase.

High-Dose Methotrexate, Ibrutinib and Temozolomide (MIT) for the Treatment of Newly Diagnosed Primary Central Nervous System Lymphoma: A Multi-Center Prospective Phase II Study

Abstract Background: Primary central nervous system lymphoma (PCNSL) is a rare and aggressive subtype of B-cell lymphoma with poor survival. Genetic alterations often occur in the chronic active B-cell receptor signaling which mediate the response to BTK inhibition (BTKi) in PCNSL. However, the efficacy of traditional high-dose methotrexate-based regimen as a first-line treatment was suboptimal with a short effective remission time and low response rate. Therefore, we initiated this phase II trial to investigate the efficacy of novel induction combination of high-dose methotrexate (HD-MTX) plus ibrutinib and temozolomide (MIT), in the treatment of newly diagnosed PCNSL for the first time (ClinicalTrials.gov identifier: NCT04514393). Methods: Patients aged 18-75 years, newly diagnosed PCNSL and at least one measurable or evaluable lesion were enrolled. The MIT induction treatment included six cycles of HD-MTX (3.5 g/m 2, every three weeks), ibrutinib (560 mg/d, after HD-MTX clearance), and temozolomide (150 mg/m2 d1-d5, every three weeks). After the completion of the six cycles of MIT induction treatment, ASCT consolidation (only for patients < 65 years) or daily ibrutinib maintenance (560 mg/d) were administered up to two years, or until disease progression, intolerable toxicity, or death. Treatment response was evaluated by brain MRI and FDG-PET and/or cerebrospinal fluid (CSF) examination every two cycles of MIT treatment. The primary objective of this study was to evaluate the overall response rate (ORR) of MIT induction treatment. The safety profile of MIT was also investigated. At the same time, next generation sequencing (NGS) of baseline tissues and dynamic monitoring with CSF/ plasma ctDNA were performed by Nanjing Geneseeq Technology Inc. Results: Between July 2021 and October 2022, thirty-three patients were enrolled in this open-label, multi-center phase II prospective clinical study. The median age was 56 years (range: 27-75) and 17 of them were male. Eye involvement occurred in 5 patients (15%). Twenty-five patients (76%) had multiple cerebral lesions. The best ORR was 94% and complete response rate was 73%. The median follow-up was 17.5 months (range: 5.8-21.3 months) for survivors. Twenty-three patients underwent ibrutinib maintenance after 6 cycles of induction therapy. The swimmer plot of the 33 patients was shown in Figure 1. The 1-year progression-free survival was 66.4% (95%CI: 58.1-74.7%) and overall survival was 90.5% (95%CI: 85.2-95.8%) (Figure 2). Treatment-related toxicities were acceptable, with grade 3-4 neutropenia occurring in 9%, thrombocytopenia in 6%, subdural hematoma (SH) in 6%, and atrial fibrillation in 3%. The 2 patients with SH recovered following discontinuation of ibrutinib. No fungal infections and treatment-related deaths were observed. NGS of Tissue/CSF was tested in 30 patients, 19 (63%) of whom were classified as MCD subtype, 2 (7%) as BN2 subtype. The mutational profiles of baseline tissue and/or CSF samples revealed that PIM1 and MYD88 mutations were present in 75.9% and 65.5% of the entire cohort followed by BTG2 (55.2%) and CD79B (51.7%). Patients with dynamic CSF ctDNA monitoring during MIT treatment were analyzed (Figure 1). The consistence of ctDNA clearance in CSF/plasma samples and imaging complete remission was observed. Patients with clearance of ctDNA in the CSF after 2 cycles of MIT treatment achieved better PFS. Conclusions: The novel induction treatment of MIT achieved encouraging responses in newly diagnosed PCNSL patients with acceptable toxicities. The early clearance of ctDNA in CSF may be related to favorable survival. Disclosures No relevant conflicts of interest to declare.

Factors influencing delayed clearance of high dose methotrexate (HDMTX) in pediatric, adolescent, and young adult oncology patients.

To identify modifiable risk factors associated with prolonged clearance of methotrexate in pediatric, adolescent, and young adult (AYA) oncology patients receiving high dose methotrexate (HDMTX). A single institution, retrospective chart review of patients receiving HDMTX between 2010-2017. Patients had a diagnosis of either leukemia or osteosarcoma. Data included demographics, concurrent intravenous (IV) medications, IV fluids (IVF) administered, urine output (UO), and rises in serum creatinine (RSC) reflective of renal toxicity (RT). Outcome measures included 1) delayed targeted MTX clearance (DC), 2) actual time to clearance (TTC) and 3) length of stay (LOS). Data from 447 HDMTX administrations were analyzed. The sample consisted of 241 (54%) osteosarcoma encounters, and 206 (46%) leukemia encounters, with an average patient age of 12.7 years. Multivariate analysis showed that DC was associated with the diagnosis of leukemia (OR 7.64, p <.0001), and less UO on day 1 (OR 0.76, p=0.005). Increased TTC was associated with increasing age (RR 1.02, p<0.0001), higher 24-hour MTX levels (RR 1.001, p=0.012) and 48-hour MTX levels (RR 1.02, p<0.0001), RT (RR 1.004, p<0.0001), use of IV lorazepam (RR 1.08, p=0.001) and IV metoclopramide (RR 1.08, p<0.001) both on day 3. Like TTC, LOS was affected by MTX levels at 24 (RR 1.001, p=0.025) and 48 hours (RR 1.03, p<0.0001), RT (RR 1.006, p<0.0001), total IV medications on day 3 (RR 1.042, p<0.0001), and the use of leucovorin on day 2 (RR 0.93, p=0.002). Multiple modifiable risk factors were identified which can be leveraged to improve HDMTX clearance. Subsequent efforts will assess whether acting on such risk factors can improve MTX clearance and shorten LOS.

A Prospective Study of Methotrexate in Combination with Ibrutinib and Temozolomide (MIT) in Newly Diagnosed Primary CNS Lymphoma

Background: Primary central nervous system lymphoma (PCNSL) is a rare non-Hodgkin lymphoma ,High-dose methotrexate (HD-MTX) systemic chemotherapy is considered as the first-line standard therapy for PCNSL, but the ORR of HD-MTX-based chemotherapy was 60%~70%.The activation of the B-cell receptor pathway has been identified as a key mechanism of PCNSL and BTK inhibitor is a promising agent. Here we aimed to investigate the safety and efficacy of induction treatment, high-dose methotrexate in combination with ibrutinib and temozolomide (MIT) in newly diagnosed PCNSL. Methods: This open-label， single-arm, multi-center phase II prospective study(NCT04514393) was designed to enroll 33 patients , and 25 patients have response (approx 75%), the MIT treatment would be considered effective. Eligible patients were ≥18 and ≤75 years of age with adequate organ function, with at least one measurable lesion. The MIT induction treatment included six cycles of high-dose methotrexate (HD-MTX, 3.5 g/m2, every three weeks), ibrutinib (560 mg/d, after HD-MTX clearance), and temozolomide (150 mg/m2 d1-d5, every three weeks). After the completion of the six cycles of MIT induction treatment, ASCT consolidation (only for patients < 65 yr) and daily ibrutinib (560 mg/d) were administered up to two years, or until disease progression, intolerable toxicity, or death. Treatment response was evaluated by brain MRI and FDG-PET and/or cerebrospinal fluid (CSF) examination every two cycles of the induction MIT treatment. The primary endpoint was the overall response rate (ORR) of the 6 cycles of MIT induction treatment for PCNSL evaluated by investigator. The safety of the treatment were also investigated. Baseline and sequential CSF/plasma samples were collected and underwent targeted next-generation sequencing (NGS). Results: Between July 2021 and July 2022, thirty-one newly diagnosed PCNSL patients with no prior therapy were enrolled and 28 patients accepted at least 2 cycles of MIT treatment. The median age of the patients was 53 yr (range: 27-75) and15/28 (53.6%) were male. By data cutoff, 12/28 (42.9%) patients had completed six cycles of treatment, 9/28 had completed 4 cycles of treatment, and 7/28 had completed 2 cycles of treatment. The ORR was 92.9% (26/28), and CR rate was 67.9% (19/28). Among 12 patients had completed 6 cycles of treatment, 11/12 (91.7%) patients achieved CR, 1 patient achived PR. Among 9 patients had completed 4 cycles of treatment, 4 (44.4%) achived CR, 3/9 (33.3%) achived PR. Among 7 patients had completed 2 cycles of treatment, 4 (57.1%) patients achieved CR and 3 (42.8%) pateints achived PR. The mutation profiles of dynamic CFS and plasma ctDNA were collected and analyzed. The most commonly mutated genes in CSF were PIM1, MYD88, BTG2, CD79B, IRF4, and ETS1. The Cerebrospinal fluid protein (CSF-TP) and CSF cfDNA concentration (ng/ml), ctDNA MAF, and ctDNA concentration (hGe/ml), MAF,and hGe/ml were positively correlated. We compared gene profiles of patients in response and no response. KMT2D gene mutations were more commonly detected in patients with progression disease compared to patients responding to treatment (P=0.03). Interestingly, detectable baseline plasma ctDNA and post-treatment CSF ctDNA were significant associated with progression disease (P=0.03, P=0.004, respectively). This clinical trial is still on going. Conclusions: The MIT induction treatment could achieve higher responses compared with HD-MTX-based chemotherapy in newly diagnosed PCNSL patients and the adverse events are manageable.

Impact of Anticonvulsant - Methotrexate Interactions on High Dose Methotrexate Clearance and Outcomes in Patients with Primary CNS Lymphoma

Background: Patients with primary CNS Lymphoma (PCNSL) often present with neurologic complications such as focal defects, neuropsychiatric symptoms, increased intracranial pressure, aphasia, seizures, and ocular symptoms which require initiation of prophylactic or therapeutic anticonvulsants. Most anticonvulsants are notorious for their pharmacodynamic and pharmacokinetic drug interactions. The cornerstone of PCNSL therapy is the utilization of high-dose methotrexate (HD-MTX). The pharmacokinetics of HD-MTX are uniquely sensitive to both disease biology and drug interactions. Due to the importance of both HD-MTX and anticonvulsants in PCNSL patients, these medications are frequently given in concert with one another despite theoretical and proven drug interactions published in the literature. This is a retrospective analysis of patients treated with a modified R-MPV regimen (rituximab, methotrexate, procarbazine, vincristine alternating with intrathecal methotrexate) and the effects of various anticonvulsants on HD-MTX clearance.Methods: Patients ≥18 years of age with a biopsy proven diagnosis of PCNSL at Roswell Park Comprehensive Cancer Center who received R-MPV between January 2002 and December 2019 were included in this retrospective analysis. The electronic health record of each patient was reviewed for specific patient demographics, laboratory results, confounding drug interactions, toxicity, and treatment outcomes. Descriptive statistics were computed for all categorical variables. The time to MTX clearance in hours and the potential impact of concomitant use of various anticonvulsants were assessed using the Wilcoxon Rank Sum test in the case of ordinal responses and the Pearson chi-square test or Fisher's Exact test for categorical variables where appropriate.Results: A total of 67 patients met the inclusion criteria of which 53 patients (79.1%) received anticonvulsants (189 cycles of R-MPV) and 14 did not (69 cycles of R-MPV). Patients who had seizures or frontal brain PCNSL were more likely to receive anticonvulsants (p <0.001). When considering all possible medication interactions with HD-MTX, use of any interacting medication within 48 hours prior to HD-MTX was a predictor of delayed clearance (p = 0.0398). The most common confounding interaction seen in this population were with proton pump inhibitors. Levetiracetam was the most common anticonvulsant used at any point in time during treatment (83.1%). Compared to no anticonvulsant, levetiracetam did not significantly prolong HD-MTX clearance (52.6h v. 72.7h, p = 0.1586). Other anticonvulsants utilized included phenytoin (24.5%), gabapentin (3.8%), valproate (3.8%), carbamazepine (1.9%), lacosamide (1.9%), lamotrigine (1.9%), and phenobarbital (1.9%). Of the patients who received an anticonvulsant, 11 received more than one over the treatment period. Time to clearance of HD-MTX for patients not on an anticonvulsant was 53.8 hours compared to a clearance time of 68.2 hours for those who received an anticonvulsant (p = 0.0571). Patients who received anticonvulsants had a significantly higher complete response rate (79.2% vs 35.7%, p = 0.009), longer progression free survival (25.4 mo vs 3 mo, p = 0.014) and overall survival (56.6 mo vs 4.6 mo, p = 0.002) compared to those who did not (Table 1). There was no difference in grade 3/4 toxicities between anticonvulsants and no anticonvulsants except for thrombocytopenia (p = 0.047) and respiratory side effects (p = 0.035).Conclusion: Anticonvulsants are an essential component to PCNSL therapy in patients on HD-MTX. They are well tolerated, do not alter HD-MTX clearance in a clinically significant manner and may help improve patient outcomes. [Display omitted] DisclosuresTorka: TG Therapeutics: Membership on an entity's Board of Directors or advisory committees.

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

PurposeLow 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.MethodsWe 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.ResultsRapid 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.ConclusionA 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.

Risk prediction for delayed clearance of high-dose methotrexate in pediatric hematological malignancies by machine learning.

This study aimed to establish a predictive model to identify children with hematologic malignancy at high risk for delayed clearance of high-dose methotrexate (HD-MTX) based on machine learning. A total of 205 patients were recruited. Five variables (hematocrit, risk classification, dose, SLC19A1 rs2838958, sex) and three variables (SLC19A1 rs2838958, sex, dose) were statistically significant in univariable analysis and, separately, multivariate logistic regression. The data was randomly split into a "training cohort" and a "validation cohort". A nomogram for prediction of delayed HD-MTX clearance was constructed using the three variables in the training dataset and validated in the validation dataset. Five machine learning algorithms (cart classification and regression trees, naïve Bayes, support vector machine, random forest, C5.0 decision tree) combined with different resampling methods were used for model building with five or three variables. When developed machine learning models were evaluated in the validation dataset, the C5.0 decision tree combined with the synthetic minority oversampling technique (SMOTE) using five variables had the highest area under the receiver operating characteristic curve (AUC 0.807 [95% CI 0.724-0.889]), a better performance than the nomogram (AUC 0.69 [95% CI 0.594-0.787]). The results support potential clinical application of machine learning for patient risk classification.

Evaluation of time to clearance of high‐dose methotrexate using the ARK immunoassay in pediatric hematology/oncology patients: A single‐center experience

A retrospective, single-center, observational study evaluated the difference in time to clearance of high-dose methotrexate between the fluorescence polarization immunoassay (FPIA) and ARK methotrexate assay in pediatric hematology/oncology patients. The post-ARK immunoassay group had an increase in clearance time of 33h/cycle and 31% increase in cycles with delayed clearance. On posthoc analysis, use of an adjusted clearance threshold of <0.15µmol/L post-ARK immunoassay, as opposed to the traditional <0.1µmol/L threshold, would have similar incidence of delayed clearance. The ARK immunoassay demonstrated a positive bias compared to the FPIA in clinical practice, which led to an institutional policy change.

Evaluation of the toxicity profile and clearance of high dose methotrexate in children with acute lymphoblastic leukemia from a tertiary cancer centre of South India

Evaluation of the toxicity profile and clearance of high dose methotrexate in children with acute lymphoblastic leukemia from a tertiary cancer centre of South India

Assessing the impact of adding acetazolamide to oral or intravenous sodium bicarbonate as compared with intravenous bicarbonate monotherapy as urinary alkalinization in adults receiving high-dose methotrexate

High-dose methotrexate (HD-MTX) requires urine alkalinization to pH ≥ 7 for adequate excretion to prevent toxicity. Due to shortages of IV sodium bicarbonate (IV-NaHCO3), few reports have demonstrated utility of oral bicarbonate (PO-NaHCO3); however, the addition of acetazolamide (Acet) has not been well described. Our study compares outcomes between alkalinization methods of IV-NaHCO3 monotherapy versus IV-NaHCO2 + Acet and PO-NaHCO3 + Acet. A single-center, IRB exempt, retrospective review was conducted from Jan 2016 to Sept 2019 of adults receiving HD-MTX ≥ 500mg/m2. The primary outcome was time from start of alkalinization to pH ≥ 7. Secondary outcomes included time from start of alkalinization to initiation of HD-MTX, time to MTX clearance, length of stay (LOS), percentage of urine pH assessments < 7, and incidence of MTX toxicity. Statistical analysis was performed using SAS9.4 with alpha 0.05. Overall demographics (n = 196 HD-MTX cycles for 55 patients) include a mean age 55years, HD-MTX dose ~ 5400mg/m2, and 69% with a diagnosis of lymphoma. Adjusting for baseline demographic differences among groups, median time from first dose alkalinization to pH ≥ 7 and to start of HD-MTX was longer for those receiving IV-NaHCO3 (n = 41) vs either IV-NaHCO3 + Acet (n = 70) or PO-NaHCO3 + Acet (n = 76) (p = 0.0001). HD-MTX clearance to a level < 0.1μmol/L was not improved with the addition of Acet. No difference existed among groups for pH results < 7, LOS, or incidence of MTX toxicity (p > 0.05). Addition of Acet to NaHCO3 reduces time to pH ≥ 7 and initiation of HD-MTX but does not appear to improve LOS, MTX toxicities, or time to MTX clearance.

Do intravenous fluid substitutions influence methotrexate clearance? An unanticipated impact of an intravenous sodium bicarbonate drug shortage.

National drug shortages of essential medications for childhood cancer have increasingly posed a challenge in the treatment of patients. The efficacy of standardized supportive care practices to avoid treatment-related toxicities may be limited during these drug shortages. High-dose methotrexate (HDMTX) plays a critical role in modern treatment protocols for acute lymphoblastic leukemia and requires stringent supportive care measures to mitigate toxicity. As the result of a national intravenous (IV) sodium bicarbonate shortage, institutional standard HDMTX supportive care guidelines had to be modified. We describe the unanticipated consequences on HDMTX clearance. We performed a retrospective chart review assessing the impact of alternative compositions of IV fluids on the mean 24-h methotrexate levels (Cpss ) of 25 patients receiving 76 total HDMTX infusions at Texas Children's Hospital Cancer Center from March to October 2017. During the sodium bicarbonate drug shortage, all patients received IV hydration consisting of either dextrose 5%, 0.45% normal saline (D5 ½ NS-Group A) or dextrose 5%, 0.2% normal saline (D5 ¼ NS-Group B). Patients receiving a higher total sodium dose demonstrated significantly lower Cpss (25.36 ± 16.6 μMol) compared to patients receiving less sodium (53.9 ± 37.9 μMol; P<.001). Our report shows that in the setting of IV sodium bicarbonate shortage, the composition of hydration IV fluids may affect methotrexate clearance. Patient who received a higher sodium load had a lower 24-h methotrexate level. This demonstrates the potential for unanticipated outcomes resulting from national drug shortages.

High-Dose Methotrexate in Pediatric Acute Lymphoblastic Leukemia: Predictors of Delayed Clearance and the Effect of Increased Hydration Rate on Methotrexate Clearance.

ObjectivesHigh-dose methotrexate (HDMTX) is an important chemotherapeutic agent in the treatment of many cancers. Identification of the predictors of poor clearance during HDMTX infusions could advance the introduction of improved supportive care to prevent toxicities and reduce hospital length of stay. The purpose of this study was to identify relationships between patient physical characteristics and HDMTX clearance in the treatment of pediatric acute lymphoblastic leukemia (ALL). At our hospital, patients who have delayed methotrexate (MTX) clearance during a cycle of HDMTX receive an increased rate of hydration with subsequent cycles. This increase in hydration rate was examined for its potential to mitigate predictors of poor clearance and to prevent nephrotoxicity.MethodsThis study retrospectively examined the treatment records of 87 pediatric patients diagnosed with ALL who were treated on or according to Children’s Oncology Group (COG) protocols AALL0232, AALL0434, AALL1131, and AALL1231. Each patient received four cycles of HDMTX (5 g/m2 over 24 hours) at two-week intervals. Patients received either 125 ml/m2/hour (standard) or 200 ml/m2/hour (delayed clearance protocol) hydration before, with, and after each infusion. MTX levels taken at 24-, 42-, and 48-hour time points were used as an indirect measure of drug clearance. Two-tailed inference for ordinary least squares regression and both heteroskedastic and paired two-tailed t-tests were performed to identify physical characteristics associated with delayed MTX clearance and the effects of hydration rate on MTX clearance, respectively.ResultsPatient age and body surface area (BSA) were found to have statistically significant (p<0.05) positive associations with the serum MTX levels at 24, 42, and 48 hours in cycle 1. Age and BSA were significant only at the 24-hour time point in cycles 2 and 4. Weight alone was not associated with delayed MTX clearance. For patients who had delayed MTX clearance once and thus received the delayed clearance protocol in subsequent cycles, increasing the hydration rate from 125 to 200 ml/m2/hour was associated with a statistically significant decrease in average MTX levels as well as serum creatinine levels at the 24-, 42-, and 48-hour time points. Once patients with delayed clearance received the 200 ml/m2/hour rate of hydration, the history of prior poor clearance lost its predictive value for serum MTX levels and delayed clearance.ConclusionsThese results suggest that patient age and BSA are significant predictors of MTX clearance if all patients receive the same rate of hydration. Age and BSA affect the distribution phase of MTX kinetics, with downstream effects in the elimination phase. Increased hydration mitigates the effects of these physical characteristics on the elimination phase kinetics by improving renal elimination of MTX, causing a loss of significance of age and BSA as predictors of MTX levels in subsequent cycles at the 42- and 48-hour time points, but with less effect at 24 hours. Thus, hyperhydration regimens prior to cycle 1 of HDMTX could be considered for patients presenting with risk factors of advanced age or high BSA to avoid delayed clearance.

Re-challenge with High Dose Methotrexate vs. Reduced Dose After Methotrexate Toxicity in Pediatric Osteosarcoma:Case Report

Introduction: Methotrexate (MTX), a classic antifolate, is one of the most widely used and well-studied anticancer agents. High-dose methotrexate (HD-MTX) with folinic acid (leucovorin) rescue is one of the standard therapies for osteosarcoma. High-dose methotrexate (HDMTX) can exert significant toxicity and requires complex pharmacokinetic monitoring and leucovorin rescue. The side effect profile of MTX varies markedly according to the dose. Regimens containing MTX are classified as high, intermediate, or low-dose. High-dose methotrexate (HD-MTX; 12 g/m2) is a part of the golden standard therapy for pediatric osteosarcoma (OS). Risk factors associated with MTX toxicity in children with OS are not well defined. Case Presentation: We report here a case of pediatric osteosarcoma with nephrotoxicity associated with delayed MTX excretion who was successfully managed using supportive measures that encouraged us to re-challenge with a full dose of MTX then we reduced the dose to 50% to attain the final critical decision about continuation or changing the regimen of treatment for the patient. Our patient developed moderate renal complications during therapy that improved with supportive care, so we challenged with more cycles of a high dose MTX, but the patient developed serious renal complications. A reduced dose of MTX with 50% was given successfully without any renal impairment. Conclusion: Methotrexate toxicity that might not occur during the initial courses of high-dose MTX is not a predictive of the tolerability of further courses and re-challenging with HDMTX is risky, but reduced dose methotrexate is a good option rather than changing the regimen, with good tolerability and rapid clearance of HDMTX. HDMTX-induced renal impairment occurs in a low percentage of patients with osteosarcoma and can be managed successfully by maximum supportive care. MTX clearance can be affected by gender and age.

Ibrutinib-based combination therapy exhibited therapeutic benefit in newly diagnosed primary central nervous system lymphoma.

2556 Background: Ibrutinib has shown single-agent activity in relapse/refractory (R/R) primary central nervous system lymphoma (PCNSL), and the high dose methotrexate (HD-MTX) has been the backbone of treatment of de-novo PCNSLs. Combination therapy of HD-MTX and ibrutinib has recently shown activity in R/R PCNSLs. Methods: Eleven newly diagnosed PCNSL patients who underwent combination therapy of HD-MTX and ibrutinib were analyzed for treatment response and safety profile. HD-MTX was given at 3.5 g/m2 every 2 weeks for a total of 8 doses. Ibrutinib was held on days of HD-MTX infusion until HD-MTX clearance. Single-agent daily ibrutinib was administered continuously after completion of induction therapy until disease progression, intolerable toxicity, or death. Patients’ clinicopathologic characteristics were retrospectively reviewed and genomic traits were further analyzed. Results: Nine out of 11 patients have completed the induction phase of ibrutinib-based combination therapy and received ibrutinib maintenance in addition to two patients whose disease progressed during the therapy. An objective response rate (ORR) of 82% (9/11) was observed, including 7 patients with complete response (CR, 64%) and 2 patients with partial response (PR, 18%). The median progression-free survival (PFS) was 7.4 months while the median overall survival (OS) was not reached. The combination therapy of HD-MTX and ibrutinib was well tolerated and has acceptable safety. In addition, the presence of ctDNA in cerebrospinal fluid (CSF) samples closely correlated with tumor response. Sustained tumor responses were associated with the clearance of ctDNA from the CSF. Conclusions: Combination of ibrutinib and HD-MTX has acceptable safety and has demonstrated anti-tumor activity in newly diagnosed de-novo PCNSL patients. The detection of ctDNA in CSF is feasible for monitoring tumor burden in PCNSL patients.

Effect of Levetiracetam on Time to High-Dose Methotrexate Clearance in Patients With Hematologic Malignancies.

High-dose methotrexate (HDMTX) is a commonly used treatment for hematologic malignancies involving the central nervous system. Two case reports described possible delayed methotrexate clearance in patients receiving concurrent levetiracetam, while a retrospective cohort study did not find this association. The objective of this single-center, retrospective case-control study of 121 patients who received their first cycle of HDMTX was to investigate the association between HDMTX clearance time and concomitant levetiracetam use. The most common diagnosis was primary central nervous system lymphoma (47.9%). The mean HDMTX dose was 4601 mg/m2 (standard deviation [SD], 2052.6mg/m2 ). Concurrent levetiracetam was administered in 30 of 121 patients (24.8%), with a mean total daily levetiracetam dose of 1434.4mg (SD, 622.9mg; range, 900-3000mg). Baseline characteristics were similar between patients who received concomitant levetiracetam and those who did not. The mean time to methotrexate clearance was 82.5 hours (SD, 51.2; 95% confidence interval, 69.4-95.7) in the concomitant levetiracetam group and 72.4 hours (SD, 31.2; 95% confidence interval, 61.7-83.0) in the nonlevetiracetam group, which was not significantly different (P > .05), even in the subgroup receiving methotrexate doses >3500mg/m2 . Grade 3 or higher toxicity occurred in 33.3% of the concomitant levetiracetam group and in 34.1% of nonconcomitant levetiracetam patients. This study, which, to our knowledge, is the first examining levetiracetam effect on only the first dose of HDMTX, supports the larger retrospective study finding no significant effect of levetiracetam on HDMTX clearance time, and suggests that administering concomitant levetiracetam does not affect HDMTX toxicity.

Phase 1b trial of an ibrutinib-based combination therapy in recurrent/refractory CNS lymphoma

AbstractIbrutinib is a first-in-class inhibitor of Bruton tyrosine kinase (BTK) and has shown single-agent activity in recurrent/refractory central nervous system (CNS) lymphoma. Clinical responses are often transient or incomplete, suggesting a need for a combination therapy approach. We conducted a phase 1b clinical trial to explore the sequential combination of ibrutinib (560 or 840 mg daily dosing) with high-dose methotrexate (HD-MTX) and rituximab in patients with CNS lymphoma (CNSL). HD-MTX was given at 3.5 g/m2 every 2 weeks for a total of 8 doses (4 cycles; 1 cycle = 28 days). Ibrutinib was held on days of HD-MTX infusion and resumed 5 days after HD-MTX infusion or after HD-MTX clearance. Single-agent daily ibrutinib was administered continuously after completion of induction therapy until disease progression, intolerable toxicity, or death. We also explored next-generation sequencing of circulating tumor DNA (ctDNA) in cerebrospinal fluid (CSF) before and during treatment. The combination of ibrutinib, HD-MTX, and rituximab was tolerated with an acceptable safety profile (no grade 5 events, 3 grade 4 events). No dose-limiting toxicity was observed. Eleven of 15 patients proceeded to maintenance ibrutinib after completing 4 cycles of the ibrutinib/HD-MTX/rituximab combination. Clinical responses occurred in 12 of 15 patients (80%). Sustained tumor responses were associated with clearance of ctDNA from the CSF. This trial was registered at www.clinicaltrials.gov as #NCT02315326.

Predictors of Delayed Clearance and Toxicities from High Dose Methotrexate in Patients Receiving Hypercvad Regimen for Treatment of Lymphoid Malignancies

Introduction: High dose Methotrexate (HDMTX) has been the backbone of chemotherapeutic regimens used for the treatment of lymphoid malignancies. Altered disposition of MTX may result in increased systemic exposure accompanied by severe adverse effects and organ toxicities. Diversity in toxicity profile has been shown to be associated with various clinical factors as well as genetic polymorphisms. In particular, single nucleotide polymorphisms (SNPs) in the solute carrier organic anion transporter 1B1 (SLCO1B1) gene especially rs4149056 and rs2306283 had been previously reported to be significantly associated with MTX concentration at 24 hours post-infusion, MTX AUC from 0-48 hours, MTX clearance and toxicities in the Caucasian pediatric population.Aim: This study aimed to characterize clearance and toxicity profile [in particular acute kidney injury (AKI) and hepatotoxicity]; and identify clinical and genetic covariates associated with clearance and toxicities of HDMTX in patients receiving HyperCVAD-B regimen for treatment of lymphoid malignancies in the local setting.Methods: This single-centered, retrospective study included all treatment-naïve patients of Asian descent who received HDMTX as part of the HyperCVAD-B regimen for treatment of lymphoid malignancies from January 2008 to December 2015 in Department of Hematology, Singapore General Hospital. Pertinent clinical data including baseline demographics, disease characteristics, treatment details, plasma MTX levels, and treatment outcomes were extracted from case notes and electronic records onto a standardized data collection form. Association between toxicities parameters and MTX levels were analyzed. Genotyping for two SNPs in the SLCO1B1 gene namely, rs2306283 and rs4146056 was using blood samples obtained from the Hematology Department Tissue Repository. Primary endpoint was incidence of delayed clearance and toxicities of HDMTX in the study population. Secondary endpoints included clinical factors and genetic covariates associated with reduced MTX clearance and toxicities.Results: A total of 102 patients (215 treatment cycles) were included, with each patient receiving median of 2 cycles (range, 1 to 6). Median age was 45 years (range, 18 - 69), and 58 (56.9%) were male. Eighty-seven patients were diagnosed with acute lymphoblastic leukemia (ALL), whereas 12 patients had lymphoma. Sixty-one patients (59.8%) were found to have at least 1 episode of delayed clearance, occurring in 89 (41.4%) treatment cycles. Median time to MTX clearance was significantly longer in patients with delayed clearance at 69.8 hours (range, 4.5-277.2) as compared to 41 hours (range, 0 - 86.3 hours), p<0.001. Approximately 25% and 47% of the patients developed AKI and hepatotoxicity attributable to MTX, respectively. A significant association between delayed clearance and occurrence of AKI was observed, with 24% of patients with delayed clearance developing AKI vs 2% in those without delayed clearance, p<0.001. Number of treatment cycles [odds ratio (OR) = 2, 95% confidence interval (CI) 1.3 - 3.1, p = 0.002]; and age ≥ 40 (OR 3.7, 95% CI 1.4 - 9.6, p = 0.008) were found to be associated with delayed clearance. Occurrence of delayed clearance (OR = 29, 95% CI = 3.7 - 228, p = 0.001), and baseline hepatic impairment (OR = 9.5, 95% CI = 2 - 45, p = 0.005) were found to predict for AKI and hepatotoxicity, respectively. Genotyping for SLCO1B1 rs2306283 and rs4146056 was carried out for 39 patients with samples available in the repository. Frequencies and outcomes were shown in Table 1 and Table 2, respectively. Due to the small sample size, no definitive correlations between specific genotypes and clearance and outcomes could be elucidated.Conclusion: Delayed clearance of HDMTX occurred in a substantial proportion of patients at approximately 60%, which was in turn associated with occurrence of AKI. Risk of delayed clearance seemed to increase with age (≥ 40) and number of treatment cycles. This underscores the need for more effective strategies to facilitate clearance of HDMTX especially in patients with identified risk factors. Larger sample size would be essential to determine associations between genotypes and clearance and toxicities. [Display omitted] [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Anti-Fungal Prophylaxis Using Intermediate Dose Ambisome Is Associated with Delayed Methotrexate Clearance in Pediatric Patients Undergoing Allogeneic Hematopoietic Stem Cell Transplantation

Pediatric patients with hematologic malignancies undergoing allogeneic hematopoietic stem cell transplantation (aHSCT) comprise a patient cohort at highest risk of developing disseminated fungal infections. Invasive aspergillosis post-HSCT is associated with unacceptably high mortality in pediatric patients with overall survival of only 15-34%. Hospital construction and excavation further potentiate the risk of fungal related morbidity and mortality in the post-HSCT setting. The current standard of care for anti-fungal prophylaxis for children undergoing aHSCT is the use of triazoles. However, 40% of healthcare associated mold infections in pediatric leukemia patients exposed to hospital construction are historically resistant to voriconazole. Methods to optimize prevention of fungal infections in this high-risk population are critical to improving pediatric aHSCT survival outcomes.We hypothesized that pre-emptive ambisome prophylaxis would be tolerated in the post-HSCT setting and would decrease the incidence of voriconazole resistant healthcare-associated fungal infections and resultant morbidity. We explored the use of intermediate dose daily ambisome (3mg/kg/day) as fungal prophylaxis in 5 patients with hematologic malignancies (2=ALL, 2=AML, 1=Lymphoblastic lymphoma) undergoing allogeneic stem cell transplantation in proximity to construction and excavation. Patient demographics, disease, donor source, conditioning regimen, methotrexate course and transplant related morbidity are shown in table 1.We found that 5 of 5 patients experienced delayed clearance of low dose methotrexate (MTX). This delayed clearance resulted in delayed methotrexate dosing in 3 of 5 patients and a missed methotrexate dose in 1 patient who subsequently developed GVHD and complications from high dose steroids. 4 of 5 patients experienced acute kidney injury (AKI), demonstrated by doubling of the pre-HSCT creatinine value following MTX administration. This identified creatinine elevation is increased as compared to historical controls receiving standard anti-fungal prophylaxis with azole agents.It has been described that AKI delays the clearance of high dose methotrexate. Here, we demonstrate that intermediate doses of daily ambisome following allogeneic HSCT is associated with AKI and delayed clearance of low doses of methotrexate used for GVHD prophylaxis in pediatric patients. Delayed methotrexate clearance was associated with development of morbidity including inadequate GVHD prophylaxis and possible resultant development of GVHD. Combined ambisome and low dose MTX is associated with AKI and delayed MTX clearance and thus is a constrained strategy for prevention of invasive fungal disease in the post-HSCT pediatric setting. The implication of these finding can be extrapolated beyond the construction setting implying cautious use of intermediate dose ambisome prophylaxis in combination with low dose MTX GVHD prophylaxis in pediatric patients post aHSCT. [Display omitted] DisclosuresPorteus:CRISPR Therapeutics: Consultancy, Equity Ownership.

A clinical variable-based predictive model of delayed clearance of high dose methotrexate (HDMTX) in patients (pts) with primary CNS lymphoma (PCNSL).

2040Background: HDMTX remains the backbone of therapy for pts with PCNSL and delayed clearance may lead to higher rates of treatment-induced toxicities. It is unknown whether readily available pre-...

Evaluation of incidence and risk factors for high-dose methotrexate-induced nephrotoxicity.

High-dose methotrexate (doses ≥1 g/m(2)) is a key component of several chemotherapy regimens used to treat patients with leukemia or lymphoma. Despite appropriate precautions with hydration, urine alkalinization, and leucovorin, nephrotoxicity remains a risk which can lead to significant morbidity and mortality. Current reports of risk factors for nephrotoxicity focus on patients with nephrotoxicity with a lack of comparison to those without toxicity. This study aimed to describe the incidence of high-dose methotrexate-induced nephrotoxicity at our institution and determined risk factors for high-dose methotrexate-induced nephrotoxicity by examining characteristics of patients with and without nephrotoxicity. This was a retrospective, single-center, chart review. Adult patients with a diagnosis of leukemia or lymphoma who received high-dose methotrexate were included. Serum creatinine values were used to evaluate nephrotoxicity according to Common Terminology Criteria for Adverse Events criteria v4.03. Data related to the following proposed risk factors were collected: age, sex, body mass index, methotrexate dose, number of high-dose methotrexate exposures, leucovorin administration route, baseline renal function, albumin, hydration status, Clostridium difficile infection, urine pH, and concomitant interacting and nephrotoxic medications. The primary endpoint was evaluated with exact binomial methods and risk factors were identified using multivariable random-effects logistic regression. Final analyses included 140 patients with 432 high-dose methotrexate exposures. There were no differences in baseline demographical characteristics. Fifty-four patients (38.6%) experienced nephrotoxicity of any grade: 27.9% with grade 1, 5.7% with grade 2, 3.6% grade 3, 0% with grade 4, and 1.4% with grade 5 toxicity. More patients in the toxicity group received doses of methotrexate ≥3 g/m(2) (58.3% versus 57.2%, p < 0.001), had an albumin level <3 g/dL (31.9% versus 15.9%, p = 0.04), and received an interacting medication during high-dose methotrexate clearance (44.4% versus 24.7%, p = 0.003). Male gender (OR 2.3, 95% CI: 1.27-4.18, p = 0.006), albumin (OR 0.44, 95% CI: 0.26-0.75, p = 0.002), number of drug interactions (OR 1.60, 95% CI: 1.15-2.21, p = 0.005), and use of furosemide (OR 2.56, 95% CI 1.46-4.48, p = 0.001) were all independent risk factors for the development of nephrotoxicity. Nephrotoxicity is a possible complication of therapy with high-dose methotrexate with most instances comprising grade 1-2 toxicity. Male gender, low albumin, and administration of interacting drugs or furosemide during high-dose methotrexate clearance may predispose patients to nephrotoxicity.