High-dose Methotrexate Toxicity Research Articles

Navigating methotrexate toxicity: Examining the therapeutic roles of folinic acid and glucarpidase.

Methotrexate (MTX) toxicity varies depending on factors such as dosing frequency (acute or repeated), dosage (low or high) and the administration route (oral, parenteral or intrathecal). Renal impairment can trigger or exacerbate MTX toxicity. Acute oral low-dose MTX (LDMTX) overdoses seldom lead to toxicity due to the saturable maximal bioavailable dose, but toxicity risks increase with repeated low doses (>3 days), high-dose MTX (HDMTX) or intrathecal poisoning. Folinic acid shares MTX transporters in the gut and cells and bypasses the MTX-induced dihydrofolate reductase inhibition. The required folinic acid dosage differs for low-dose and high-dose MTX toxicities. Acute LDMTX poisoning rarely requires folinic acid, while chronic LDMTX poisoning needs low-dose folinic acid until cellular function is restored. In HDMTX toxicities, early intravenous folinic acid administration is recommended, with dose and duration being guided by MTX concentrations and clinical improvement. In intrathecal MTX poisoning, folinic acid should be administered intravenously. Glucarpidase, a recombinant bacterial enzyme, has a high affinity for MTX and folate analogues in the intravascular or intrathecal systems. It decreases serum MTX concentrations by 90%-95% within 15 min. Its primary indication is for intrathecal MTX poisoning. It is rarely indicated in HDMTX toxicity unless patients have renal injury. However, there is no literature evidence supporting its use in HDMTX poisoning. Its use is limited by its significant cost and lack of availability. Haemodialysis can be potentially useful for MTX removal in cases where glucarpidase is not available. Additionally, fluid hydration, renal support and urine alkalinization are important adjunctive therapies for managing MTX toxicities.

Impact of Folinic Acid Dosing on Efficacy and Toxicity of High-Dose Methotrexate in Central Nervous System Lymphoma

Treatment of primary central nervous system lymphoma (PCNSL) is centered around a backbone of high-dose methotrexate (HDMTX) with folinic acid (FA) rescue. Higher FA doses were associated with treatment failure in several retrospective studies in acute lymphatic leukemia (ALL), leading to the adoption of lower FA doses in ALL treatment protocols. In PCNSL, FA doses have varied widely, guidelines and consensus statements generally do not address FA dosing, and the effect of FA dosing on treatment outcomes has not been assessed. We retrospectively analyzed the medical records of patients treated at our institute for PCNSL between the years 2014 and 2022 to address this question. Patient characteristics are listed in table 1. Complete dosing data was available for 36 patients. The median number of HDMTX doses administered was 6.5 (range, 2-9;), with an average dose of 3.9 g/m 2 (SD +/- 0.74; range, 2.7-5.0). Per the local protocol, IV FA rescue began 24 hours after each MTX infusion at a fixed dose of 50 mg four times daily and continued until MTX clearance. The average cumulative dose of FA administered per treatment was 322 mg/m 2 (SD +/- 141; range, 140-700). 33 patients (92%) achieved either a partial or complete response on MRI following induction treatment. Three (8%) had progressive disease. 26 patients (72%) proceeded with consolidation treatment. Of these, 16 (44%) underwent autologous hematopoietic stem cell transplant. At a median follow up of 1.6 years (range, 0.3-8.1), 12 patients (33%) suffered progressive disease, disease relapse, or death. The 2-year PFS probability for the entire cohort was estimated at 64.5% (95% confidence interval [CI], 49.4-84.1%), and the 2-year OS as 70.7% (95% CI 56.0-89.2%). In univariate Cox regression analysis, average FA dose during MTX treatment was a significant predictor of both PFS and OS, with hazard ratios (HR) of 2.22 (95% CI 1.39-3.55; p < 0.001) and 2.07 (95% CI 1.31-3.29; p = 0.002), respectively, for each 100 mg/m 2 increase. The FA dose during the first treatment cycle, before assessment of response, was also significantly associated with worse PFS (HR 1.56; 95% CI 1.24-1.96; p < 0.001) and OS (HR 1.41; 95% CI 1.14-1.74; p = 0.001). A trend towards worse PFS and OS was seen with male gender, elevated serum LDH, and deep structure involvement. A Cox multivariate regression analysis using the variables age, gender, serum LDH, deep structure involvement, and the average MTX and FA doses, identified FA dose as an independent prognostic factor for PFS, with an estimated hazard ratio (HR) of 2.23 for each 100 mg/m 2 increase (95% CI, 1.25-3.97; p = 0.006). A smaller effect was seen when the FA dose during only the first treatment cycle was examined (HR 1.55; 95% CI 1.16-2.08; p = 0.003). Involvement of deep structures was also significantly associated with worse PFS, with an estimated HR of 8.59 (95% CI, 1.28-57.5; p = 0.027), and there was a borderline significant trend for worse PFS with male gender and elevated LDH. None of the examined variables were identified as statistically significant predictors of OS in the multivariate analysis. Logistic regression with 2-year PFS as the dependent variable was used to define a cutoff value of 350 mg/m 2 for FA dose. The group of patients who received FA doses above and below this threshold showed significantly different PFS curves (figure 1). The 2-year PFS probability was estimated at 56.6% (95% CI, 35.4-90.5%) for patients who received doses of FA above this threshold, and 70.5% (95% CI, 51.7%-96.2%) for patients who received doses below it. We identified no effect of FA dosing on hematologic, renal, hepatic, or gastrointestinal toxicity at the dose ranges examined. In summary, we found that high FA doses were associated with inferior PFS in PCNSL. Such high doses may be avoided through use of lower individual doses of FA, such as 15 mg/m 2 or 25 mg fixed doses as have been used in some protocols, rather than the 50 mg or higher doses used in our and other's practice. Our conclusions are moderated by the study's limitations, which include a small sample size limited to a single center and a retrospective design. However, they suggest that optimizing FA dosing in treatment of PCNSL might improve treatment efficacy without excess toxicity. Future larger and prospective studies will be required to better define the range of MTX and FA doses at which the balance between prevention of treatment toxicity and preservation of treatment efficacy is preserved.

Clinical Outcomes in Patients with High-Dose Methotrexate Toxicity Treated with Vs. without Glucarpidase

Background. High-dose methotrexate (HDMTX) is a cornerstone of treatment for lymphoma and leukemia involving the central nervous system, but can cause significant toxicity, which manifests predominantly as acute kidney injury (AKI) as well as bone marrow suppression and hepatotoxicity. Glucarpidase is a recombinant bacterial enzyme that cleaves 99% of circulating MTX to inactive metabolites within 15 minutes of its administration. It is approved for use in the setting of supratherapeutic MTX levels to mitigate renal and extrarenal toxicity. Despite its potent biochemical effects, no study has rigorously examined whether glucarpidase improves clinical outcomes in patients with HDMTX toxicity compared to controls not treated with glucarpidase. This key evidence gap has led to wide variation in the use of glucarpidase across institutions. Methods. We examined the clinical outcomes of patients with HDMTX-associated AKI (HDMTX-AKI) treated with and without glucarpidase across a large multicenter cohort of 684 adults from 26 major cancer centers across the US from 2000 to 2022. HDMTX-AKI was defined as a ≥1.5-fold increase in serum creatinine (SCr) within 4 days following treatment with HDMTX. We collected data on demographics, comorbidities, medications, laboratory values, and outcomes. The primary outcome was renal recovery, defined as a return of SCr to <1.5-fold baseline and absence of renal replacement therapy-dependence at hospital discharge. Prespecified subgroup analyses included those treated with glucarpidase in the first 60 hours following MTX initiation, and those with AKI stage 3 (increase in SCr ≥3-fold baseline) in the first 4 days following treatment with HDMTX. Secondary outcomes included absence of neutropenia, transaminitis, and mucositis on day 7. We used multivariable logistic regression to adjust for potential confounders. Models were adjusted for age, sex, race, baseline eGFR, body mass index, hypertension, diabetes mellitus, coronary artery disease, congestive heart failure, chronic liver disease, baseline WBC count, serum albumin, and LDH, MTX dose and infusion duration, urine pH, volume of IV fluids administered, leucovorin dose, and maximum fold-change in SCr, oliguria, and receipt of concomitant nephrotoxins in the first 4 days following MTX initiation. Results. Among the 684 patients with HDMTX-AKI, 207 (30.3%) were treated with glucarpidase and 477 (69.7%) were not. All patients treated with glucarpidase received it within the first 96 hours following initiation of HDMTX. The median time from HDMTX initiation to glucarpidase receipt was 54 hours (IQR, 44-66), with 65% of the patients receiving it within 60 hours, and 85% within 72 hours. Patients treated vs. not treated with glucarpidase were similar with respect to age, sex, race, MTX dose and infusion duration, and most baseline labs, including SCr, but had high higher plasma MTX levels at 24 and 36 hours and more severe AKI ( Table). Glucarpidase receipt was associated with a 2.43-fold higher adjusted odds of renal recovery (95% CI, 1.38-4.27) compared to no glucarpidase receipt ( Figure). The magnitude of association was considerably higher when the analysis was restricted to those treated with glucarpidase in the first 60 hours (odds ratio 4.94 [95% CI, 2.42-10.06] and to those with AKI stage 3 (odds ratio 7.08 [95% CI, 2.27-22.10]) ( Figure). Glucarpidase receipt was also associated with a higher likelihood of recovery from neutropenia and normalization of alanine aminotransferase (ALT) by day 7 ( Figure). There was no significant association between glucarpidase receipt and mucositis on day 7 ( Figure). Conclusions. In the largest study to date of HDMTX-AKI and the only one, to our knowledge, to include control patients, we found that patients who received glucarpidase had considerably higher odds of renal recovery, as well as recovery from neutropenia and normalization of liver enzymes, compared to those who did not receive glucarpidase. The magnitude of association with renal recovery was particularly evident in those treated with glucarpidase in the first 60 hours and in those with AKI stage 3. Though this is an observational study with the potential for residual confounding, our data support use of glucarpidase in patients with HDMTX-AKI, particularly in the first 60 hours following initiation of MTX.

Impact of Folinic Acid Dosing on Efficacy and Toxicity of High-Dose Methotrexate in Central Nervous System Lymphoma

IntroductionHigh-dose methotrexate (HDMTX)-based regimens are the treatment of choice in primary central nervous system lymphoma (PCNSL). Folinic acid (FA) rescue is used to mitigate the toxic effects of MTX on normal cells. However, the optimal dosing of FA in PCNSL remains uncertain. MethodsWe analyzed the relationship between FA dosing and treatment efficacy and toxicity in a cohort of 36 PCNSL patients treated at our institute between the years 2014 and 2022. A combination of univariate and multivariate analyses using known prognostic factors were used to determine the association between FA dosing and treatment outcomes. ResultsWe found that higher per-treatment cumulative FA doses were associated with inferior progression-free survival (PFS), with a hazard ratio (HR) of 2.2 for each 100 mg/m2 increase in FA dose. We identified a threshold of 350 mg/m2/treatment, above which there was a significant reduction in PFS. Notably, lower FA doses did not result in increased toxicity. ConclusionOur findings suggest that optimizing FA dosing to avoid very high rescue doses may improve treatment outcomes in PCNSL patients receiving HDMTX. Further prospective studies are warranted to validate these findings.

High-Dose Methotrexate: Nursing Considerations for Administration and Supportive Care.

High-dose methotrexate (HDMTX) is the backbone of many pediatric and adult oncology treatment protocols. It requires appropriate monitoring and supportive care because delayed elimination of MTX can lead to serious toxicities. No reviews specifically addressing nursing management regarding standard treatment protocols and delayed MTX elimination exist. This article provides an overview of HDMTX treatment and nursing considerations, including toxicities, components of supportive care management, and strategies to manage administration and delayed elimination of MTX. A review of published literature and guidelines was performed to evaluate nursing considerations for patients receiving HDMTX. Using existing and novel tools, nurses can closely monitor patients and provide supportive care to mitigate HDMTX toxicity. Early identification of delayed MTX elimination and subsequent treatment with glucarpidase, if appropriate, has been associated with shorter length of hospital stay and decreased incidence of grade 4 toxicities and mortality.

Relationship between methylenetetrahydrofolate reductase gene polymorphisms and methotrexate drug metabolism and toxicity.

Acute lymphoblastic leukemia (ALL) is the most common malignancy in children, and methotrexate (MTX) is the key drug for ALL. Studies on the relationship between High-Dose methotrexate (HD-MTX) toxicity and methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C genes have drawn different conclusions. This study aimed to investigate the relationship between the polymorphism of MTHFR C677T and A1298C genes and the toxicity responses of MTX. The MTHFR C677T and A1298C genotypes of 271 children with ALL who received HD-MTX chemotherapy in southern China from September 2017 to June 2021 were analyzed, and the toxicity of HD-MTX was evaluated and analyzed according to Common Terminology Criteria for Adverse Events (CTCAE) 5.0. The MTHFR C677T and A1298C gene polymorphisms were not correlated with the 48-hour MTX blood concentrations (P>0.05). Unconditional logistic regression model analysis also revealed that the risk of liver function impairment [odds ratio (OR) =1.656, 95% confidence interval (CI): 1.179-2.324, P<0.05] and mucosal damage (OR =1.508, 95% CI: 1.042-2.183, P<0.05) were 1.656 and 1.508 times higher for the heterozygous mutant (CT), and homozygous mutant (TT) mutant type than for the wild-type (CC), wild-type, respectively. The risk of neutropenia and liver function impairment were 0.498 (OR =0.498, 95% CI: 0.251-0.989, P<0.05) and 6.067 (OR =6.067, 95% CI: 1.183-31.102, P<0.05) times higher in low-risk children with CT+TT mutant genotypes than in those with CC wild genotypes, respectively. Furthermore, the risk of mucosal damage was 1.906 times higher in high-risk children with the CT+TT genotype than in those with the CC genotype (OR =1.906, 95% CI: 1.033-3.518, P<0.05). The MTHFR A1298C genotypes differed in the incidence of liver function damage and gastrointestinal toxic reactions in children with ALL. Nonetheless, no increased risk of liver function impairment nor gastrointestinal reactions in children with the heterozygous mutant (AC)+CC mutation was observed. Advancements in MTHFR genotype testing in children with ALL and the introduction of personalised treatments based on genotype results during HD-MTX chemotherapy will help to predict, prevent, and reduce the occurrence of adverse MTX-related toxic reactions.

CNS prophylaxis in aggressive B-cell lymphoma

The prevention of central nervous system (CNS) relapse in diffuse large B-cell lymphoma (DLBCL) continues to be one of the most contentious areas of lymphoma management. Outcomes for patients with secondary CNS lymphoma (SCNSL) have historically been very poor. However, in recent years improved responses have been reported with intensive immunochemotherapy approaches, and there is a growing interest in potential novel/cellular therapies. Traditional methods for selecting patients for CNS prophylaxis, including the CNS International Prognostic Index, are hampered by a lack of specificity, and there is accumulating evidence to question the efficacy of widely employed prophylactic interventions, including intrathecal and high-dose methotrexate (HD-MTX). Given the potential toxicity of HD-MTX in particular and the ongoing need to prioritize systemic disease control in high-risk patients, there is an urgent need to develop more robust methods for identifying patients at highest risk of CNS relapse, as well as investigating prophylactic interventions with greater efficacy. Here we review new evidence in this field from the last 5 years, focusing on the potential use of molecular diagnostics to improve the identification of high-risk patients, recent large data sets questioning the efficacy of HD-MTX, and the current approach to management of patients with SCNSL. We provide a suggested algorithm for approaching this very challenging clinical scenario.

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

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

Acute toxicity due to delayed elimination of methotrexate in cancer therapy: A case report

High-dose methotrexate (HD-MTX) is widely administered in cancer therapy, and generally includes doses of 500 mg/m 2 or higher. Administration of such high doses of methotrexate is followed by leucovorin rescue therapy. The leucovorin rescue is intended to minimize damage to healthy cells; otherwise, Delayed elimination of methotrexate can lead to serious adverse events and even death, despite of the preventive measures. We report herein a case of a 25-year-old woman having Acute Lymphoblastic Leukemia (ALL) who showed delayed elimination of MTX associated with functional kidney failure, spinal cord aplasia, persistent ulcers of the oral cavity and liver damage. This patient received a cumulative dose of 906 mg/m 2 (1.315 g) over 43 hours followed by Leucovorin (Folinic Acid) rescue at 4H after the end of MTX infusion. The monitoring of MTX plasma levels showed a high concentration at 72 H (2.45 μmol/L) and at 96H (2.23 μmol/L). In fact, MTX levels remained above 0.2 μmol/L until H144. Elevation of creatinine and transaminases has been reported in the first 24 H post-infusion and reaching their maximum (Creat = 337 μmol/L, ASAT = 85UI/L, ALAT = 155IU/L) at 72 H leading to the readjustement of the Leucovorin rescue to 800 mg/D at 96H. Once the MTX levels are below the cytotoxic threshold (0.01 μmol/L), the folinic acid rescue was stopped and the outcome was favorable with a decrease of creatinine and transaminases levels. This case clearly demonstrates the role of therapeutic drug monitoring, particularly in long period infusions, where the toxicity of HD-MTX may be more prominent causing kidney damage which can lead to delayed elimination and liver damage responsible of the elevation of MTX levels, a condition which requires precise dosage of folinic acid because conventional doses are no longer covering the real needs to limit MTX toxicity.

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

BackgroundRepeated 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.MethodsThirty 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.ResultsThe 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).ConclusionsSerum 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.

High dose methotrexate in adult Egyptian patients with hematological malignancies: impact of ABCB1 3435C > T rs1045642 and MTHFR 677C > T rs1801133 polymorphisms on toxicities and delayed elimination

High dose methotrexate (HDMTX) is an essential agent in chemotherapeutic regimens used in various hematological malignancies in Egyptian adults. The research for the impact of gene polymorphism on HDMTX induced toxicities and delayed elimination is an important ongoing objective in many studies, variable and conflicting results produced in the past years to clarify that impact. This study aimed to investigate the role of ABCB1 3435 C > T rs1045642 and MTHFR 677 C > T rs1801133 polymorphisms on HDMTX induced toxicity outcomes and delayed elimination in Egyptian adult patients with hematological malignancies. A prospective, observational cohort study was conducted on a total of 62 Egyptian adult patients with hematological malignancies age ≥ 18-years-old. All demographic, medical, and laboratory data were continuously collected from the patients’ medical files in an up-to-date follow-up in selected clinics during the period from April 2018 to March 2020. Venous blood samples were collected for the purpose of genotyping, DNA extraction, and measurement of MTX levels. All the relevant data were statistically analyzed. The studied patients' median age was 25 years old with a range of (18–62) years. Forty-six patients were males with about 74%, and 16 were females with about 26%. Eighty-nine percent of the patients diagnosed with acute lymphoblastic leukemia ‘ALL’, 5% of the patients had B cell non-hodgkin lymphoma ‘B-NHL’ and 3% diagnosed with primary central nervous system lymphoma ‘PCNSL’ and Burkitt’s lymphoma ‘BL’ Hematological, hepatic, renal and gastrointestinal toxicities observed post-HDMTX were recorded with the hematological toxicities toping on all the others, also patients with delayed elimination at 72 hours post the HDMTX dose were determined. Statistical analysis revealed a significant association between ABCB1 3435 C > T rs1045642 and HDMTX delayed elimination with about 10 times higher risk among the minor allele ‘T’ carriers (p-value = 0.006) (odds ratio [OR]: 10.470; 95% CI: 1.961–55.904). No significant association observed between the studied gene polymorphisms: MTHFR 677 C > T rs1801133, ABCB1 3435 C > T rs1045642, and different toxicity outcomes. According to our best knowledge, this study is the first to conclude a significant association between ABCB1 3435 C > T rs1045642 gene polymorphism and HDMTX delayed elimination at 72 hours post HDMTX infusion; also, it is the first study to analyze the association between ABCB1 3435 C > T rs1045642 polymorphism with HDMTX toxicity and delayed elimination in adult Egyptian patients with hematological malignancies.

The Role of Genetic Polymorphisms in High-Dose Methotrexate Toxicity and Response in Hematological Malignancies: A Systematic Review and Meta-Analysis.

Objective: High-dose methotrexate (HDMTX) is a mainstay therapeutic agent for the treatment of diverse hematological malignancies, and it plays a significant role in interindividual variability regarding the pharmacokinetics and toxicity. The genetic association of HDMTX has been widely investigated, but the conflicting results have complicated the clinical utility. Therefore, this systematic review aims to determine the role of gene variants within the HDMTX pathway and to fill the gap between knowledge and clinical practice. Methods: Databases including EMBASE, PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), and the Clinical Trials.gov were searched from inception to November 2020. We included twelve single-nucleotide polymorphisms (SNPs) within the HDMTX pathway, involving RFC1, SLCO1B1, ABCB1, FPGS, GGH, MTHFR, DHFR, TYMS, and ATIC. Meta-analysis was conducted by using Cochrane Collaboration Review Manager software 5.3. The odds ratios (ORs) or hazard ratios (HRs) with 95% confidence interval (95% CI) were analyzed to evaluate the associations between SNPs and clinical outcomes. This study was performed according to the PRISMA guideline. Results: In total, 34 studies with 4102 subjects were identified for the association analysis. Nine SNPs involving MTHFR, RFC1, ABCB1, SLCO1B1, TYMS, FPGS, and ATIC genes were investigated, while none of studies reported the polymorphisms of GGH and DHFR yet. Two SNPs were statistically associated with the increased risk of HDMTX toxicity: MTHFR 677C>T and hepatotoxicity (dominant, OR=1.52, 95% CI=1.03-2.23; recessive, OR=1.68, 95% CI=1.10–2.55; allelic, OR=1.41, 95% CI=1.01–1.97), mucositis (dominant, OR=2.11, 95% CI=1.31–3.41; allelic, OR=1.91, 95% CI=1.28–2.85), and renal toxicity (recessive, OR=3.54, 95% CI=1.81–6.90; allelic, OR=1.89, 95% CI=1.18–3.02); ABCB1 3435C>T and hepatotoxicity (dominant, OR=3.80, 95% CI=1.68-8.61), whereas a tendency toward the decreased risk of HDMTX toxicity was present in three SNPs: TYMS 2R>3R and mucositis (dominant, OR=0.66, 95% CI=0.47–0.94); RFC1 80A>G and hepatotoxicity (recessive, OR=0.35, 95% CI=0.16–0.76); and MTHFR 1298A>C and renal toxicity (allelic, OR=0.41, 95% CI=0.18–0.97). Since the data of prognosis outcomes was substantially lacking, current studies were underpowered to investigate the genetic association. Conclusions: We conclude that genotyping of MTHFR and/or ABCB1 polymorphisms prior to treatment, MTHFR 677C>T particularly, is likely to be potentially useful with the aim of tailoring HDMTX therapy and thus reducing toxicity in patients with hematological malignancies.

Relationship Between the Free and Total Methotrexate Plasma Concentration in Children and Application to Predict the Toxicity of HD-MTX.

High-dose methotrexate (HD-MTX) can be highly effective as well as extremely toxic. Many drug molecules can bind to plasma proteins to different extents in vivo, whereas only the free drug can reach the site of action to exert a pharmacological effect and cause toxicity. However, free MTX concentrations in plasma have not been reported. Traditional analyses of free drugs are both cumbersome and inaccurate. We collected 92 plasma samples from 52 children diagnosed with ALL or NHL or other lymphomas that were treated with HD-MTX. The hollow fiber centrifugal ultrafiltration (HFCF-UF) was used to prepare plasma samples for analysis of the free MTX concentration. Protein precipitation was employed to measure the total MTX concentration. The HFCF-UF is a simple method involving a step of ordinary centrifugation; the validation parameters for the methodological results were satisfactory and fell within the acceptance criteria. A linearity coefficient r 2 of 0.910 was obtained for the correlation between the free and total MTX plasma concentrations in 92 plasma samples. However, the free and total MTX concentrations was only weakly correlated in 16 clinical plasma specimens with total MTX concentrations >2 μmol L−1 (r 2 = 0.760). Both the free and total MTX concentrations at 42 h were negatively correlated with the creatinine clearance (CCr) level (P = 0.023, r = −0.236 for total MTX and P = 0.020, r = −0.241for free MTX, respectively). The free MTX concentration could not be accurately estimated from the total MTX concentration for patients with high MTX levels which are conditions under which toxic reactions are more likely to occur. High plasma MTX levels could become a predictor of the occurrence of MTX nephrotoxicity to draw people's attention. The proposed HFCF-UF method is a simple and accurate way to evaluate efficacy and toxicity in clinical therapeutic drug monitoring.

BMI Is Not Associated with Toxicity to High Dose Methotrexate: A Single Institution Retrospective Study of 147 Patients

Background: High-dose methotrexate (HD-MTX) with leucovorin rescue is frequently used in the treatment of various lymphomas, breast cancer, and sarcomas and remains an important therapy for lymphoma with CNS involvement. Despite its efficacy, HD-MTX can carry considerable toxicity which can lead to prolonged hospital stays, invasive therapies, and delays/discontinuation of a potentially curative treatments. Previous studies have shown that advanced age, male sex, use of proton pump inhibitors and impaired creatinine clearance are associated with higher rates of MTX toxicity (May et al 2014). However, the impact of body mass index (BMI) on the risk of toxicity with HD-MTX has not previously been reported. We performed a retrospective analysis of all patients at Washington University in St. Louis who were treated with HD-MTX to evaluate the relationship between BMI and risk of toxicity. Methods: Consecutively treated adult patients at Washington University in St. Louis who were treated with HD-MTX (&amp;gt;1,000mg/m2) for any malignancy (excluding leukemia) from 2005-2011 were identified via our pharmacy database. Baseline patient data was collected via retrospective review of the medical record including age, sex, diagnosis, methotrexate dose received, baseline renal and liver function tests, evidence for HD-MTX toxicity, concomitant medications. HD-MTX toxicity was defined as by delayed methotrexate clearance, acute kidney injury, liver function abnormalities, mucositis, or acute kidney injury, disease status and survival. Delayed methotrexate clearance was defined as serum methotrexate level of greater than 15umol/L at 24 hours, greater than 1.5umol/L at 48 hours, or greater than 0.15umol/L at 72 hours based on prior studies (May et al 2014). Results: 147 patients were included who received a total of 496 cycles of methotrexate (58 CNS lymphoma, 26 DLBCL, 11 T-cell lymphoma, 12 Burkitt's lymphoma, 2 mantle cell lymphoma, 27 sarcoma, 10 breast cancer, 1 other). 2 patients with B-ALL were excluded. The median age was 50 years (range 19-80) with 14 patients who were ≥70 years. Patients each received a median of 2.5 cycles of HD-MTX (range 1-12) at doses of ≤3.5g/m2 (n=248) and &amp;gt;3.5g/m2 (n=248). The total incidence of HD-MTX toxicity in this cohort was 52.4% (260/496 administrations) and did not differ between those who received doses ≤3.5g/m2 (n=248) or &amp;gt;3.5g/m2 (n=248) (OR: 0.875, 95% CI: 0.61-1.25). Median OS was not impacted by presence or absence of MTX toxicity (66 mo vs 84 mo p=0.78). Patients who experienced toxicity had longer clearance than those who did not (5.8 days vs 3.1 days, p=&amp;lt;0.001). Use of proton pump inhibitors was associated with a higher risk of MTX toxicity (OR 1.8, 95% CI: 1.25-2.6). Use of concomitant antibiotics (OR 1.024, 95% CI: 067-1.6) and age &amp;gt;70 (OR 0.64, 95% CI: 0.185-2.2) were not independent risk factors for HD-MTX toxicity. The median BMI of patients was 25.3 (range 14.7-44.9). 6.1%, 40.8%, 27.2%, and 25.9% had BMIs of underweight (&amp;lt;18.5), normal (18.5-25), overweight (25-30), obese (&amp;gt;30) respectively. We used the restricted cubic spline smoothing method to model the functional form of the association between BMI and MTX toxicity. We found that there is no significant association between BMI and MTX toxicity (p=0.898). The 95% confidence bands contain a flat line such that there is no associated change in the probability of having a MTX toxicity event for any given change in BMI. When comparing patients who had normal BMI or underweight compared to those who had BMIs above normal, there was no significant difference in the rate of methotrexate toxicity. Conclusions: In this cohort of patients treated with HD-MTX, we found that BMI is not a risk factor in the development of toxicity. Our analysis also suggests that a single incidence of HD-MTX toxicity does not significantly impact patient survival, which is similar with previous findings (May, Leukemia &amp; Lymphoma 2013). Determining potential risk factors for HD-MTX toxicity will allow clinicians to be better prepared to manage complications and tailor treatment regimens based on individual patient characteristics. Disclosures Mehta-Shah: Genetech: Research Funding; Karyopharm Therapeutics: Consultancy; Bristol Myers-Squibb: Research Funding; C4 Therapeutics: Consultancy; Celgene: Research Funding; Innate Pharmaceuticals: Research Funding; Kyowa Kirin: Consultancy; Verastem: Research Funding.

Patterns of Treatment and Survival in Elderly Patients with Primary CNS Lymphoma; An 11-Year Population-Based Analysis

Introduction Primary CNS lymphoma (PCNSL) is an aggressive form of lymphoid malignancy that occurs exclusively in the brain, meninges, spinal cord, and eyes. The incidence of PCNSL has been increasing, particularly in the elderly population, with a median age at diagnosis of 66 years (Olson J.E. et al., Cancer 2002). The primary modality of treatment for this deadly disease is systemic chemotherapy that includes high-dose methotrexate (HD-MTX), with or without whole-brain radiation. Due to the toxicity of HD-MTX, physicians tend to avoid using it in the elderly population. This was confirmed in previous reports from the 1990s (Panageas K.S. et al., Cancer 2007). In this comprehensive population-based analysis, we sought to examine the patterns of treatment and survival in elderly patients in the 2000s and sought to investigate clinical and socioeconomic predictors of treatment selection. Methods We conducted a retrospective cohort analysis using de-identified data accessed from the national cancer database (NCDB). The NCDB provided records of 2985 patients diagnosed with PCNSL between 2004 and 2015. We excluded patients who are younger than 65 years old, those who tested positive for HIV, and those who started treatment &amp;gt;120 days since diagnosis to account for immortal time bias. Patients were divided into four groups based on treatment received: combined modality treatment (CMT), chemotherapy alone, radiation alone, and no treatment. Exploratory analysis of the patient groups was performed. Summary statistics are presented as percentages for categorical data and median with interquartile range for quantitative data. Multivariate regression models were used to analyze predictors of the selection of any treatment versus no treatment and for selecting chemotherapy versus no chemotherapy. To account for variable baseline characteristics, we used propensity score weighting methodology to calculate estimates of interest. Survival estimates were performed using the Kaplan-Meier method, and survival differences were tested using the wilcoxon-rank test. Results We identified 1096 patients with PCNSL who fulfilled the inclusion criteria. The median age was 73 (IQR: 68-79). There were 52% males. The majority of the patients were whites (92%), lived in a metropolitan area (78%), treated at an academic/research center (57%). The most common treatment modality used was chemotherapy alone (48%), followed by CMT (22%), no treatment (16%), and radiation alone (13%). On multivariate analysis, age (OR: 0.94, 95% CI 0.92-0.96) and comorbidity score (OR: 0.63, 95% CI 0.52-0.76) significantly predicted receiving any type of treatment. Both age (OR: 0.91, 95% CI 0.89-0.94) and distance (OR: 1.006, 95% CI 1.001-1.01) were predictors of receiving chemotherapy. Median follow up was 12 months (IQR: 3-44). Median OS in months for the four groups was: 43.1 for CMT, 19.4 for chemotherapy alone, 17.2 for radiation alone, and 2.3 for no treatment. (wilcoxon-rank test p-value: &amp;lt;0.001). Median OS for the whole population was 17 months (IQR: 12-26). Patients &amp;gt;75 year old had lower median OS in general, but receiving CMT had a survival advantage as well. (Figures 1 and 2) Conclusions The majority of PCNSL patients in our analysis received treatment. Our results showed an increased trend of chemotherapy use in elderly patients compared with earlier reports, where radiation alone was the most common treatment modality. The median OS of patients was longer compared with the 1990s data (17 vs. 7 months). CMT was associated with better OS compared with no treatment and chemotherapy alone. Although this was numerically better compared with radiation alone, it was not statistically significant. Younger patients and patients with lower comorbidity scores were more likely to receive treatment. Younger patients and patients who live further from the treating facility were more likely to receive chemotherapy. Longer distance may have led to less radiation use due to the need for complex planning and frequent visits associated with radiation therapy. Our study is limited by its retrospective nature, which makes it at risk of selection bias. Using propensity score weighting methodology strengthens our results. Also, the NCDB lacks certain pertinent variables, such as details of chemotherapy regimens, and toxicity information especially for radiation in the CMT arm which will have practical implications. Disclosures Fazal: Glaxosmith Kline: Consultancy, Speakers Bureau; Incyte Corporation: Consultancy, Honoraria, Speakers Bureau; Karyopham: Speakers Bureau; Celgene: Speakers Bureau; BMS: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Jansen: Speakers Bureau; Stemline: Consultancy, Speakers Bureau; Gilead/Kite: Consultancy, Speakers Bureau; Agios: Consultancy, Speakers Bureau; Amgen: Consultancy, Speakers Bureau; Takeda: Consultancy, Speakers Bureau; Novartis: Consultancy, Speakers Bureau; Jazz Pharma: Consultancy, Speakers Bureau. Kahn:Genetech: Honoraria; Takeda: Honoraria; Karyopharm: Honoraria; Seattle Genetics: Honoraria; Abbvie: Honoraria; Celgene: Honoraria; AstraZeneca: Honoraria; Beigene: Honoraria.

Polymorphisms of SLC19A1 80 G>A, MTHFR 677 C>T, and Tandem TS Repeats Influence Pharmacokinetics, Acute Liver Toxicity, and Vomiting in Children With Acute Lymphoblastic Leukemia Treated With High Doses of Methotrexate.

Introduction: High dose methotrexate (HD-Mtx) is highly effective and significantly improves overall acute lymphoblastic leukemia (ALL) patients survival. The pharmacodynamics of Mtx depends on the polymorphism of genes encoding proteins engaged in the folate metabolism pathway. The aim of the current study is to determine the relationship between variants of folate metabolism-related genes and the frequency of acute toxicities of HD-Mtx.Material and Methods: A group of 133 patients aged 1.5–18.1 years (median: 6.3) was treated in accordance with the ALL-IC-2002 and ALL-IC-2009 protocols. The following polymorphisms were determined: 80 G>A SLC19A1 (solute carrier family 19 member 1; rs1051266) with direct DNA sequencing, as well as 677 C>T MTHFR (methylenetetrahydrofolate reductase; rs1801133) and the tandem repeats of the TS (thymidylate synthase) with PCR technique. HD-Mtx organ toxicities were evaluated based on the laboratory tests results and the National Cancer Institute criteria.Results: In patients with genotypes AA for SLC19A1 and CC or CT for MTHFR Mtx steady state concentrations (Css) and AUCinf were distinctly higher. In patients with genotype 3R/3R for TS initial elimination rate constant was significantly higher (P = 0.003). Patients receiving Mtx at the dose of 5 g/m2 had lower clearance (4.35 vs. 8.92 L/h/m2) as compared to the ones receiving 2 g/m2 that indicates non-linear Mtx elimination at the higher dose. Liver impairment was the most frequently observed toxicity. The homozygous genotype was associated with a significantly higher incidence of hepatic toxicity for both the SLC19A1 (P = 0.037) and TS (P = 0.002). Logistic regression analysis indicated an increased risk of vomiting for the 2R/3R genotype of the TS gene (OR 3.20, 95% CI 1.33–7.68, P = 0.009) and for vomiting and hepatic toxicity for the 3R/3R genotype (vomiting: OR 3.39, 95% CI 1.12–10.23, P = 0.031; liver toxicity: OR 2.28, 95% CI 1.05–4.95, P = 0.038). None of the acute toxicities differed between the analyzed dosing groups.Conclusions: Determination of polymorphisms of SLC19A1, MTHFR, and TS genes might allow for a better prior selection of patients with higher risk of elevated Mtx levels. Our study is the first one to report the increased risk of hepatotoxicity and vomiting in patients with TS polymorphisms.

Effect of access to care on outcomes of rural and elderly patients with primary central nervous system lymphoma.

e14008 Background: Primary central nervous system lymphoma (PCNSL) can often be cured, especially in younger patients, but requires intense chemotherapy with high-dose methotrexate (HDMTX) and rituximab to optimize outcomes. Toxicities can lead to dose reduction or omission that may increase relapse risk, or lead clinicians to select less effective regimens that do not contain HDMTX. Methods: Anonymized, de-identified data of patients from 110 community oncology practices of the Guardian Research Network (GRN, www.GuardianResearch.org ) was analyzed to determine treatments, toxicities, and outcomes of adults with PCNSL. All data from the medical record is available from GRN (diagnoses, demographics, labs, medicines, toxicities, radiology, pathology, procedures, and encounters), so each patient’s journey can be fully characterized. Results: Of 533805 adults with cancer, 49 were treated for PCNSL with HDMTX-containing regimens (n = 35), other chemotherapy regimens (n = 3), or radiation therapy (RT) alone (n = 11). HDMTX patients received HDMTX only in 8 cases, HDMTX plus rituximab in 23 cases, addition of RT in 11 cases, and HDMTX with other chemotherapy but no rituximab in 3 cases. Survival at 5 years was 53% (standard error [SE] 8.6%) for patients treated with HDMTX versus 33% (SE 13%) for those treated with other therapies. Of those treated with HDMTX, survival was 0% for patients who experienced early toxicity that required cessation of HDMTX prior to receiving 3 doses and having response evaluated versus 62% (SE 9.1%) for patients who received 3 or more courses of HDMTX (p &lt; 0.001). In a multivariable Cox proportional hazards model including completion of at least 3 doses of HDMTX, age, race, and sex, only lack of HDMTX toxicity was associated with survival (hazard ratio 0.22, 95% confidence interval 0.07 to 0.70, p = 0.01). Conclusions: Use of HDMTX and prevention of toxicity improves outcomes for PCNSL patients treated in the community.

Solitary serum methotrexate level 36hours post high-dose methotrexate: A safe, efficacious, and cost-effective strategy to monitor methotrexate toxicities in childhood leukemia in resource-limited centers.

The standard practice during high-dose methotrexate (HD-MTX) in acute lymphoblastic leukemia (ALL) to mitigate toxicity is to serially monitor levels till serum MTX<0.01μmol/L. Most resource-limited centers lack in-house access to MTX levels, and therefore repeated monitoring is costly and cumbersome. We studied the efficacy and safety of "solitary 36hours post HD-MTX levels (MTX36 )." This prospective observational study consecutively enrolled children with ALL receiving HD-MTX. Cycles with unavailable MTX36 and MTX36 >10μmol/L were excluded. HD-MTX was administered over 24 hours (BFM-2009 protocol) with 12 hours of prehydration. MTX36 were performed at other centers. Leucovorin was given in six hourly doses 36 hours post HD-MTX. Hydration was continued until the last dose of leucovorin. MTX toxicities, including change of creatinine from baseline at 36 hours (∆Cr36 ), were noted. Two groups depending on MTX36 (≤1μmol/L vs>1μmol/L) received six versus eight doses of leucovorin, and toxicities were compared. Twenty-nine children with median age five years (1-11) who received 100 HD-MTX cycles with a median MTX dose of 3 g/m2 (2-5) were analyzed. The median MTX36 level was 1.165μmol/L (0.1-7.32). Toxicities of HD-MTX (CTCAE-4.0): transaminitis-22%; creatinine elevation ≥ 1.25 times baseline-24%; cytopenias-16%; mucositis-17%; acute kidney injury (AKI)-6%. All toxicities were ≤CTCAE grade 3. Creatinine elevation, AKI, and mucositis were significantly higher in the group with higher MTX36 . There was no correlation (r=0.3) between ∆Cr36 and MTX36 . MTX36 was thrice more economical than the standard protocol. MTX36 is a potential cost-effective, efficacious, and safe limited sample strategy to monitor HD-MTX, particularly in centers where in-house MTX levels are unavailable.

Adverse effects with intravenous methotrexate in children with acute lymphoblastic leukemia/lymphoma: a retrospective study.

Methotrexate (MTX) forms the backbone of maintenance cycles in childhood acute lymphoblastic leukemia (ALL) chemotherapy, including interim maintenance. There is sufficient published data describing toxicities of high dose MTX(HD-MTX), but toxicities with escalating doses of MTX (Capizzi regimen) is not well documented. Capizzi regimen is thought to be relatively safe; we contend that even low escalating doses of MTX have significant toxicities. Our study intends to characterise such events with Capizzi MTX in comparison tothat seenwith HD-MTX. The retrospective study was conducted at a tertiary care centre of North India. We looked for the presence of six main toxicities: febrile neutropenia, thrombocytopenia, mucositis, hepatic toxicity, renal toxicity and skin toxicityfrom the clinical records of children with newly diagnosed acute lymphoblastic leukemia and lymphoma (intermediate and high risk disease), treated at our centre from November 2013 to July 2018. Intermediate risk ALL(IR-ALL) received Capizzi MTX, whereas high risk ALL (HR-ALL/T-NHL), received HD-MTX. Both these regimens do not use L-asparaginase. A total of 237 cycles of Capizzi escalating MTX and 151 cycles of HD-MTX (B cell: 3gm/m2 and T cell ALL/T-NHL: 5gm/m2) during interim maintenance were studied in 93 children. Fifty-four (54) childrenwereof IR (all B cell ALL) and 39 ofHR-ALL (21 B-ALL, 18 T-ALL/T-NHL). The combined incidence of toxicities, were similar between the two groups: 68/237 cycles (28.7%) of Capizzi MTX and 45/151 cycles (29.8%) of HD-MTX (P = 0.815). However, mucositis was more commonly witnessed in the later group at 22/151 cycle (14.6%) versus 13/237 cycles (5.5%) in Capizzi MTX (P = 0.002). Nephrotoxicity and skin toxicity was seen only in the HD-MTX group. There was no difference in the severity of toxicity, graded using NCI CTCAE v 5.0,between the two groups. There was no mortality directly attributable to methotrexate toxicity (Grade V toxicity). Serum MTX levels were available in 69/151 (45.7%) cycles of HD-MTX and showed no association with toxicity in this group. Also, there was no difference in the incidence of combined toxicities between groups with (19/69 cycles) or without (26/82 cycles) available serum MTX levels in the HR group (P = 0.577). Male gender, lower baseline ANC and lower BMI had significant association with toxicity. Methotrexate related toxicity is common with both Capizzi and HD-MTX schedule in childhood ALL with a correlation of lower BMI, baseline ANC and male gender. However, it is possible to administer Capizzi as well as HD-MTX in lower middle income countries, with manageable toxicity. Further studies will be required to substantiate our findings and determine the predictors of such events.

Retrospective evaluation and prediction of clearance and toxicity of high dose methotrexate in childhood acute lymphoblastic leukemia patients

To find the predictors of High Dose Methotrexate toxicities in childhood Acute Lymphoblastic Leukemia Patients. This study included 198 Childhood Acute Lymphoblastic Leukemia patients (303 infusions) who were treated with High Dose Methotrexate. Methotrexate levels at different time point were measured by modified enzyme multiplied immunoassay technique assay. The correlation between Methotrexate levels and toxicity was evaluated by Receiver Operating Characteristic curve. When the Methotrexate level at 42 h was lower than 0.76 µmol/L, the sensitivity for predicting thorough clearance at 66 h was 90.78%. When the Methotrexate level at 42 h was higher than1.5 µmol/L, the sensitivity for predicting delayed clearance was 82.17%. When the Methotrexate level at 66 h was higher than 0.5 µmol/L, the sensitivity for predicting Methotrexate toxicity was 89.09%. When the Methotrexate level at 66 h was lower than 0.1 µmol/L, the sensitivity for predicting Methotrexate nontoxicity was 92.73%. The Methotrexate level at 42 h could be predictor for delayed clearance. The Methotrexate level at 66 h could be predictor for toxicity.