Methotrexate and childhood leukemia

Severe Methotrexate Toxicity Following a Capizzi Cycle in an Obese Adolescent With Acute Lymphoblastic Leukemia and Hepatic Steatosis

Methotrexate is a major component of pediatric leukemia treatment. While toxicities are common after high-dose methotrexate, escalating dose methotrexate (Capizzi methotrexate) is typically well-tolerated. We report an adolescent Hispanic female with pre-B acute lymphoblastic leukemia, preexisting obesity and hepatic steatosis who developed severe multiorgan failure following an escalating dose of methotrexate with delayed methotrexate excretion of 11 days. We identified one similar report in an obese adult; however, this case is the first to our knowledge involving a pediatric patient. With the rising incidence of obesity and associated comorbidities among children and adolescents with leukemia, attention to potential risks for this population is warranted.

Influence of ADORA2A gene polymorphism on leukoencephalopathy risk in MTX-treated pediatric patients affected by hematological malignancies

BACKGROUND

Methotrexate (MTX) can lead to neurotoxicity and asymptomatic leukoencephalopathy. However, the mechanism of MTX-related leukoencephalopathy is obscure. MTX and its metabolites inhibit 5-aminoimidazole-4-carboxamide ribonucleotide formiltransferase (ATIC) and promote adenosine release. Recently, it has been reported that adenosine and its receptor are related to certain central nervous system diseases. We investigated whether adenosine pathway gene polymorphisms and clinical factors were related to MTX-related leukoencephalopathy in pediatric patients affected by hematological malignancies.

PROCEDURE

Fifty-six Japanese childhood acute lymphoblastic leukemia or lymphoma patients were investigated. Patients were evaluated by magnetic resonance imaging of the brain before maintenance therapy or stem cell transplantation. Gene polymorphisms within the adenosine pathway (ATIC, adenosine A2A receptor [ADORA2A]) and the MTX pathway (methylenetetrahydrofolate reductase [MTHFR] and ABCB1) were genotyped using TaqMan assays. Clinical data were collected by accessing the medical records. MTX-related leukoencephalopathy was evaluated by a pediatric neurologist.

RESULTS

Twenty-one (37%) of 56 patients developed MTX-related leukoencephalopathy. Four of 21 patients developed clinical neurotoxicity. The minor allele CC genotype of rs2298383 (ADORA2A) was associated with MTX-related leukoencephalopathy (P = 0.010, odds ratio = 5.81, 95% confidence interval 1.50-22.50). High cumulative dose of systemic MTX was associated with MTX-related leukoencephalopathy after adjusting for sex, ADORA2A polymorphism, and prolonged high MTX concentration (P = 0.042, odds ratio = 1.18, 95% confidence interval 1.01-1.37).

CONCLUSIONS

ADORA2A rs2298383 and high cumulative dose of systemic MTX administration were significantly associated with MTX-related leukoencephalopathy. Our results indicate that pharmacological intervention within the adenosine pathway may be both a treatment and preventative option for MTX-related leukoencephalopathy.

Methotrexate modulates folate phenotype and inflammatory profile in EA.hy 926 cells

EA.hy 926 cells grown under low folate conditions adopt a "pro-atherosclerotic" morphology and biochemical phenotype. Pharmacologically relevant doses of the antifolate drug methotrexate (MTX) were applied to EA.hy 926 cells maintained in normal (Hi) and low (Lo) folate culture media. Under both folate conditions, MTX caused inhibition of cell proliferation without significantly compromising metabolic activity. MTX treated Hi cells were depleted of folate derivatives, which were present in altered proportions relative to untreated cells. Transcript profiling using microarrays indicated that MTX treatment modified the transciptome in similar ways for both Hi and Lo cells. Many inflammation-related genes, most prominently those encoding C3 and IL-8, were up-regulated, whereas many genes involved in cell division were down-regulated. The results for C3 and IL-8 were confirmed by quantitative RT-PCR and ELISA. MTX appears to modify the inflammatory potential of EA.hy 926 cells such that its therapeutic properties may, at least under some conditions, be accompanied by the induction of a subset of gene products that promote and/or maintain comorbid pathologies.

Effects of methylenetetrahydrofolate reductase and reduced folate carrier 1 polymorphisms on high-dose methotrexate-induced toxicities in children with acute lymphoblastic leukemia or lymphoma

The authors investigated whether high-dose methotrexate-induced toxicity differed according to the presence of methylenetetrahydrofolate reductase (MTHFR) or reduced folate carrier 1 (RFC1) genetic polymorphism. The authors studied 15 children with acute lymphoblastic leukemia or lymphoblastic lymphoma who were treated using protocols that included high-dose methotrexate (3.0 g/m), for an overall total of 43 courses. Methotrexate-induced toxicities and the plasma methotrexate concentrations were evaluated retrospectively. Hematologic toxicity was the most frequently observed toxicity, appearing in 87% of the patients. In a subset of patients (47%), elevation of liver transaminase levels showed a repeated tendency to develop. High plasma methotrexate concentrations at 48 hours after the methotrexate infusion were not significantly related to methotrexate-induced toxicities except for mucositis. A generalized estimating equation analysis revealed that vomiting during the high-dose methotrexate treatment was more pronounced in patients who had a larger number of G alleles at the RFC1 80G>A polymorphism. No significant differences in the development of other toxicities or in the plasma methotrexate concentrations were observed for the different MTHFR 677C>T or RFC1 80G>A polymorphisms. This study suggests but does not prove that the RFC1 80G>A polymorphism may contribute to interindividual variability in responses to high-dose methotrexate.

Homocysteine, pharmacogenetics, and neurotoxicity in children with leukemia

PURPOSE

Despite its clinical success, methotrexate (MTX) therapy is associated with toxicities such as seizures, the pathogenesis of which remains unclear. It has been suggested that hyperhomocysteinemia is caused by MTX and is responsible for its neurotoxic effects. The purposes of this study were to explore whether hyperhomocysteinemia was related to MTX administration and toxicity and whether homocysteine or MTX toxicity differed by methylenetetrahydrofolate reductase (MTHFR) or reduced folate carrier (RFC) genetic polymorphisms.

PATIENTS AND METHODS

We studied 53 children with newly diagnosed acute lymphoblastic leukemia who were consecutively treated on a single clinical protocol that included two courses of high-dose MTX (high-dose methotrexate [HDMTX]; 2.5 or 5.0 g/m2 per day) as consolidation therapy.

RESULTS

The study participants' median plasma homocysteine concentrations at 23 and 44 hours after HDMTX (9.00 micromol/L and 10.12 micromol/L, respectively) were greater than the concentrations immediately before HDMTX (5.77 micromol/L, P <.0001 for both comparisons). Seven days after HDMTX treatment, their plasma concentration returned to baseline. Nine patients experienced seizures, and five patients experienced thrombosis during the first 15 months of therapy, with a tendency for there to be higher plasma homocysteine in patients with seizures across all time points (P =.063) but not in patients with thrombosis (P =.59). We observed no significant differences in plasma or cerebrospinal fluid homocysteine levels or in toxicity based on the MTHFR 677C/T or RFC 80G/A genotypes.

CONCLUSION

We conclude that homocysteine was transiently elevated after HDMTX and may be related to seizure risk in children with leukemia.

Effects of high-dose methotrexate on the hemostatic system in childhood acute lymphoblastic leukemia

BACKGROUND

Thromboembolic and hemorrhagic complications are significant causes of death in patients with malignancy. These are well-known with the use of certain drugs. This study was planned to investigate whether there was any effect of high-dose methotrexate on the hemostatic system in childhood acute lymphoblastic leukemia.

PROCEDURE

To evaluate the hemostatic system, we investigated coagulation screening tests (prothrombin time, activated partial thromboplastin time, and fibrinogen), coagulation inhibitors (protein C, protein S, and antithrombin III), and fibrinolytic system (fibrin degradation products and tissue plasminogen activator). These parameters were measured in 35 cycles of high dose-methotrexate (3 g/m(2)) of 20 childhood acute lymphoblastic leukemia cases at baseline and on days 1 and 7 after the therapy.

RESULTS

We found that high-dose methotrexate administration adversely affected both the coagulation system (prolonged prothrombin time and activated partial thromboplastin time and decreased fibrinogen levels) and coagulation inhibitors (decreased protein C, protein S, antithrombin III) on day 1 after chemotherapy compared to the baseline values. The hemostatic parameters began to improve on day 7 after chemotherapy, except for fibrin degradation products. Tissue plasminogen activator levels were not changed with the therapy.

CONCLUSIONS

Coagulation cascade (prolonged prothrombin time and activated partial thromboplastin time and decreased fibrinogen) and coagulation inhibitors (decreased protein C, protein S, and antithrombin III levels) have been found to be affected by high-dose methotrexate therapy, but these transient changes did not cause clinical thromboembolic or hemorrhagic complications.

Isotachophoretic analysis of the dihydrofolate reductase reaction in the presence of methotrexate and ascorbic acid

The antifolate methotrexate (MTX) is widely used in cancer chemotherapy. In this study, we show that MTX (MTX-Glu1) and MTX-polyglutamates (MTX-Glu2-5) strongly inhibited the growth of the leukemic cell line MOLT-4. This effect, however, was mitigated by ascorbic acid. We investigated whether ascorbic acid is able to reduce dihydrofolic acid (DHF) to tetrahydrofolic acid (THF) directly or by circumventing the MTX inhibition of dihydrofolate reductase (DHFR). The inhibition of this NADPH-dependent reduction of DHF by MTX-Glun in the absence or presence of ascorbate, was determined by analytical isotachophoresis. Using 0.01 M HCl/histidine, pH 6.0, as a leading electrolyte (L) and 0.005 M 2-(N-morpholino)ethanesulfonic acid (MES)/histidine, pH 6.0, as a terminating electrolyte (T), MTX-Glun derivatives including MTX-Glu1 could be easily separated, whereas the quantitative estimation of THF was not possible. A quantitative characterization of the DHFR reaction by measuring NADPH, NADP+ and ascorbate was achieved with another system (L: 0.01 M HCI/beta-alanine, pH 3.73; T: 0.01 M caproic acid, pH 3.27). Nanomolar concentrations of MTX-Glu1-5 inhibited consumption of NADPH and production of NADP+. Ascorbic acid was not able to reduce DHF, neither directly nor after inhibition of DHFR by MTX. However, ascorbic acid seemed to diminish the oxidation of THF and this may account for its capacity to reduce the inhibitory effect of MTX on MOLT-4 cells.

Development of a whole cell assay to measure methotrexate-induced inhibition of thymidylate synthase and de novo purine synthesis in leukaemia cells

The cellular pharmacology of methotrexate (MTX) is complex, involving the inhibition of both de novo thymidylate and purine biosynthesis. Measurement of MTX-induced inhibition of de novo thymidylate and purine biosynthesis may allow optimisation of MTX therapy, and the aim of this study was to develop an assay to measure the activity of both pathways in the same cell sample, and so determine the effects of MTX treatment. In situ thymidylate synthase (EC 2.1.1.45) activity was measured by the release of 3H2O from [5'-3H]deoxyuridine and de novo purine synthesis by the incorporation of [14C]formate into adenine and guanine. Incubation of human leukaemia CCRF-CEM cells for 22 hr with 50 nM MTX resulted in approximately 90% inhibition of in situ thymidylate synthase activity, relative to control untreated cells, and after exposure to 1000 nM MTX activity could not be detected. In contrast, de novo purine synthesis, measured in the same sample, was not inhibited by exposure to 50 nM MTX, although activity was again completely abolished by exposure to 1000 nM MTX. To demonstrate the utility of the assay, lymphoblasts isolated from a child with acute lymphoblastic leukaemia (ALL) were also incubated for 22 hr with 1000 nM MTX. Both in situ thymidylate synthase activity and de novo purine synthesis were significantly inhibited, by 70% and 60% respectively, relative to the activity in untreated cells.

Aminophylline for methotrexate-induced neurotoxicity

Methotrexate, a mainstay treatment for children with acute lymphoblastic leukaemia, can cause neurotoxicity, with paralysis, seizures, somnolence, anorexia, and headaches. The pathophysiology of this reaction is unknown. It has been suggested that the anti-inflammatory effect of methotrexate in patients with arthritis is due to adenosine release brought on by inhibition of purine synthesis. Since adenosine is a central nervous system depressant, we wondered whether adenosine release in the central nervous system could account for some of the neurotoxicity due to methotrexate, and whether that toxicity could be lessened by displacement of adenosine from its receptor by aminophylline. 6 patients (age 3-16 years) who had methotrexate-induced neurotoxicity unresponsive to standard treatment received 2.5 mg/kg aminophylline. In addition, the concentration of adenosine in the cerebrospinal fluid (CSF) from 11 children completing a 24-h systemic methotrexate protocol was compared with that in 8 newly diagnosed patients and 12 who had not received any treatment for at least a week. 4 of 6 patients with toxic signs and symptoms attributed to methotrexate and unrelieved by steroids, epidural blood patch, promethazine, 5-hydroytryptamine antagonists, paracetamol, and narcotics, had complete resolution of neurotoxicity after or during a 1-h infusion of aminophylline; 2 others had a pronounced improvement but persistent nausea. CSF adenosine concentrations of patients receiving methotrexate, even when there was very slight or no toxicity, were greatly increased compared with control subjects (mean values of 217 and 51 nmol/L, median 175 and 52 nmol/L). Subacute methotrexate neurotoxicity may be mediated by adenosine and relieved by aminophylline.

Bioequivalence of two methotrexate formulations in psoriatic and cancer patients

OBJECTIVE

To compare the bioequivalence of a generic methotrexate (MTX) tablet (Mylan) with that of a brand-name (Lederle) product.

DESIGN

A single-dose, randomized, crossover study.

SETTING

Clinical Research Center (CRC) at a university hospital.

PATIENTS

Men and women who had a diagnosis of malignancy or psoriasis who were at least 21 years old.

METHODOLOGY

Two overnight study periods were scheduled at the CRC at least one week, but not more than two weeks apart. Each period consisted of a 10-hour fast prior to and 4 hours following oral MTX 15 mg administered as six 2.5-mg tablets. Blood samples were collected over 48 hours. Plasma MTX concentrations were determined using an HPLC assay. Area under the curve from zero to infinity (AUC0-infinity) was calculated by the log-trapezoidal method.

RESULTS

Twenty-two patients (21 psoriasis, 1 colon cancer) aged 23-61 years completed both study periods. Mean values for peak concentration, time to peak concentration, and AUC0-infinity were 0.80 mumol/L, 1.2 hours, and 3.0 mumol.h/L, respectively, for Mylan's MTX tablets and 0.81 mumol/L, 1.4 hours, 3.0 mumol.h/L, respectively, for Lederle's MTX. Normalization for weight or body surface area did not affect interpatient variability. Relative bioavailability of generic MTX was 99.2 percent. Rate and extent of absorption were not significantly different and the confidence intervals were within the range of 80-120 percent required by the Food and Drug Administration.

CONCLUSIONS

Mylan's MTX tablet is bioequivalent to Lederle's product.