Is natural (6S)-5-methyltetrahydrofolic acid as effective as synthetic folic acid in increasing serum and red blood cell folate concentrations during pregnancy? A proof-of-concept pilot study.

BACKGROUND: North American health authorities recommend 0.4 mg/day folic acid before conception and throughout pregnancy to reduce the risk of neural tube defects. Folic acid is a synthetic form of folate that must be reduced by dihydrofolate reductase and then further metabolized. Recent evidence suggests that the maximal capacity for this process is limited and unmetabolized folic acid has been detected in the circulation. The biological effects of unmetabolized folic acid are unknown. A natural form of folate, (6S)-5-methyltetrahydrofolic acid (Metafolin®), may be a superior alternative because it does not need to be reduced in the small intestine. Metafolin® is currently used in some prenatal multivitamins; however, it has yet to be evaluated during pregnancy. METHODS/DESIGN: This double-blind, randomized trial will recruit 60 pregnant women aged 19-42 years. The women will receive either 0.6 mg/day folic acid or an equimolar dose (0.625 mg/day) of (6S)-5-methyltetrahydrofolic acid for 16 weeks. The trial will be initiated at 8-21 weeks' gestation (after neural tube closure) to reduce the risk of harm should (6S)-5-methyltetrahydrofolic acid prove less effective. All women will also receive a prenatal multivitamin (not containing folate) to ensure adequacy of other nutrients. Baseline and endline blood samples will be collected to assess primary outcome measures, including serum folate, red blood cell folate and unmetabolized folic acid. The extent to which the change in primary outcomes from baseline to endline differs between treatment groups, controlling for baseline level, will be estimated using linear regression. Participants will have the option to continue supplementing until 1 week postpartum to provide a breastmilk and blood sample. Exploratory analyses will be completed to evaluate breastmilk and postpartum blood folate concentrations. DISCUSSION: This proof-of-concept trial is needed to obtain estimates of the effect of (6S)-5-methyltetrahydrofolic acid compared to folic acid on circulating biomarkers of folate status during pregnancy. These estimates will inform the design of a definitive trial which will be powered to assess whether (6S)-5-methyltetrahydrofolic acid is as effective as folic acid in raising blood folate concentrations during pregnancy. Ultimately, these findings will inform folate supplementation policies for pregnant women. TRIAL REGISTRATION: ClinicalTrials.gov, ID: NCT04022135. Registered on 14 July 2019.

Does L-Methylfolate Supplement Methylphenidate Pharmacotherapy in Attention-Deficit/Hyperactivity Disorder?: Evidence of Lack of Benefit From a Double-Blind, Placebo-Controlled, Randomized Clinical Trial.

PURPOSE/BACKGROUND: Interventions for attention-deficit/hyperactivity disorder (ADHD) may be inadequate for some patients. There is evidence that supplementation with L-methylfolate augments antidepressant agent effects and thus might also augment ADHD treatment effects by a common catecholaminergic mechanism. METHODS: Forty-four adults with Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition diagnosis of ADHD participated in a randomized, double-blind, placebo-controlled, 12-week trial of 15 mg of L-methylfolate in combination with osmotic-release oral system methylphenidate. Osmotic-release oral system methylphenidate was dose optimized over the first 6 weeks. We evaluated the effects on ADHD symptoms, self-report on the Behavior Rating Inventory of Executive Function of executive function, methylphenidate dosing, neuropsychological test measures, the Adult ADHD Self-report scale, emotional dysregulation, social adjustment, and work productivity, as well as moderating effects of body mass index, autoantibodies to folate receptors, and select genetic polymorphisms. RESULTS: L-Methylfolate was well tolerated, with no significant effect over placebo except improvement from abnormal measures on the mean adaptive dimension of the ASR scale (χ = 4.36, P = 0.04). Methylphenidate dosing was significantly higher in individuals on L-methylfolate over time (χ = 7.35, P = 0.007). Exploratory analyses suggested that variation in a guanosine triphosphate cyclohydrolase gene predicted association with higher doses of methylphenidate (P < 0.001). CONCLUSIONS: L-Methylfolate was associated with no change in efficacy on measures relevant to neuropsychiatric function in adults with ADHD, other than suggestion of reduced efficacy of methylphenidate. Further investigation would be required to confirm this effect and its mechanism and the genotype prediction of effects on dosing.

Analytic Approaches for the Treatment of Hyperhomocysteinemia and Its Impact on Vascular Disease.

Homocysteine is an intermediary metabolite in the methionine cycle. Accumulation of homocysteine is caused either by mutation of relevant genes or by nutritional depletion of related vitamin(s). This review covers the historical background of hyperhomocysteinemia in which indispensable subjects in relation to underlying pathophysiological processes are discussed with the view of metabolism and genetics of folate and methionine cycles. This review emphasizes the unique role of homocysteine that is clearly distinct from other risk factors, particularly cholesterol in the development of vascular disease. The critical issue in understanding the role of homocysteine is the relation with plasma folic acid. The majority of subjects with homocysteine > 15 µmol/L exhibit plasma folate < 9 nmol/ L, indicating that depletion of folate is the main cause of hyperhomocysteinemia irrespective of the presence or absence of vascular disease. Furthermore, only the group of subjects with homocysteine levels > 15 µmol/L demonstrated a higher prevalence of vascular disease. Analytic approaches to treat hyperhomocysteinemia are discussed in which stepwise administration with nutritional doses of folic acid, 5-methyitetrahydrofolate (5-MTHF), and betaine is provided singly or by combined manner based on clinical and laboratory evaluations. Whether correction of hyperhomocysteinemia is able to prevent the development of homocysteine-associated vascular disease remains an unresolved issue. The review discussed a biochemical and mechanistic approach to resolve questions involved in the relation between homocysteine and the development of atherosclerotic vascular disease.

A pharmacokinetic and pharmacodynamic investigation of Modufolin® compared to Isovorin® after single dose intravenous administration to patients with colon cancer: a randomized study.

PURPOSE: Leucovorin is commonly used as folate supplement in 5-fluorouracil-based chemotherapy, but needs to be converted to active 5,10-methylenetetrahydrofolate (methyleneTHF) intracellularly. This provides for interindividual differences. MethyleneTHF has recently been developed into the stable, distributable drug, Modufolin®. The aim was to compare the concentration of folate metabolites in tumor, mucosa, and plasma of patients with colon cancer after administration of Modufolin® or Isovorin® (levo-leucovorin). METHODS: Thirty-two patients scheduled for colon resection were randomized to receive Modufolin® or Isovorin® at dosage of 60 or 200 mg/m². The study drug was given as one i.v. bolus injection after anesthesia. Plasma was collected for pharmacokinetic (PK) analysis before, during, and after surgery. Tissue biopsies were collected at surgery. Folate metabolites were analyzed by LC-MS/MS. RESULTS: MethyleneTHF and THF concentrations were significantly higher in mucosa (p < 0.01, both dosages) and tumors (p < 0.01, 200 mg/m²) after Modufolin® as compared to Isovorin® administration. The results correlated with PK observations. The Modufolin® to Isovorin® C(max) ratio for methyleneTHF was 113 at 200 mg/m² and 52 at 60 mg/m²; the AUC(last) ratios were 17 and 9, respectively. The THF plasma concentrations were also higher after Modufolin® administration (C(max) ratio 23, AUC(last) ratio 13 at 200 mg/m²; C(max) ratio 15, AUC(last) ratio 11 at 60 mg/m²). CONCLUSION: Modufolin® administration resulted in significantly higher methyleneTHF levels than Isovorin® and may potentially increase the efficacy of 5-fluorouracil-based chemotherapy. The results encourage further evaluation of Modufolin® as a substitute to Isovorin® including the potential clinical benefits.

Folate augmentation of antidepressant response.

The use of two antidepressants from the initiation of treatment in major depressive disorder has been investigated in several recent studies and forms a paradigm shift in the pharmacotherapy of the condition. Several, but not all, trials have claimed improved response and remission rates with the combinations as opposed to monotherapy. The use of folate preparations (folic and folinic acid and l-meth-ylfolate) have shown effective augmentation of antidepressant response in a variety of controlled and open-label settings in patients with normo- and hypofolatemic status. Several recent trials using L-methylfolate, the active and more bioavailable form of folic acid, have shown promising adjunctive use with a well-tolerated adverse event profile.

Folates and S-adenosylmethionine for major depressive disorder.

Interest in nonpharmaceutical supplements for treating major depressive disorder (MDD) has increased significantly, both among patients and among clinicians during the past decades. Despite the large array of antidepressants (ADs) available, many patients continue to experience relatively modest response and remission rates, in addition to a burden of side effects that can hinder treatment compliance and acceptability. In this article, we review the literature on folates and S-adenosylmethionine (SAMe), 2 natural compounds linked in the 1-carbon cycle metabolic pathway, for which substantial evidence supports their involvement in mood disorders. Background information, efficacy data, proposed mechanisms of action, and side effects are reviewed. Based on existing data, supplementation with SAMe, as well as with various formulations of folates, appears to be efficacious and well tolerated in reducing depressive symptoms. Compared with other forms of folates, 5-methyltetrahydrofolate (L-methylfolate or 5-MTHF) may represent a preferable treatment option for MDD given its greater bioavailability in patients with a genetic polymorphism, and the lower risk of specific side effects associated with folic acid. Although further randomized controlled trials in this area appear warranted, SAMe and L-methylfolate may represent a useful addition to the AD armamentarium.

Supplementation with B vitamins or n-3 fatty acids and depressive symptoms in cardiovascular disease survivors: ancillary findings from the SUpplementation with FOLate, vitamins B-6 and B-12 and/or OMega-3 fatty acids (SU.FOL.OM3) randomized trial.

BACKGROUND: Dietary factors might affect depressive symptoms. OBJECTIVE: In secondary data analyses, we examined effects of supplementation with B vitamins or n-3 (omega-3) fatty acids on depressive symptoms in cardiovascular disease survivors. DESIGN: The SUpplementation with FOLate, vitamins B-6 and B-12 and/or OMega-3 fatty acids (SU.FOL.OM3) trial was a secondary prevention trial (2003-2009; n = 2501) in which individuals aged 45-80 y were randomly assigned, by using a 2 × 2 factorial design, to receive 0.56 mg 5-methyl-tetrahydrofolate and vitamins B-6 (3 mg) and B-12 (0.02 mg); EPA and DHA (600 mg) in a 2:1 ratio; B vitamins and n-3 fatty acids; or a placebo. Depressive symptoms were evaluated at years 3 and 5 with the 30-item Geriatric Depression Scale (GDS). Overall and sex-specific ORs and 95% CIs were estimated in 2000 participants by using factorial logistic regression. RESULTS: After a median of 4.7 y of supplementation, there was no association between allocation to receive B vitamins and depressive symptoms. However, the allocation to receive n-3 fatty acids was positively associated with depressive symptoms (GDS >10) in men (adjusted OR: 1.28; 95% CI: 1.03, 1.61) but not in women. CONCLUSIONS: We showed no beneficial effects of a long-term, low-dose supplementation with B vitamins or n-3 fatty acids on depressive symptoms in cardiovascular disease survivors. The adverse effects of n-3 fatty acids in men merit confirmation.

Intensity-modulated radiotherapy combined with chemotherapy for the treatment of gastric cancer patients after standard D1/D2 surgery.

BACKGROUND: The purpose of the current study is to evaluate the efficacy and complications of concurrent chemoradiotherapy (CCRT) for the treatment of gastric cancer patients after D1/D2 surgery. METHODS: Sixty-eight untreated gastric cancer patients (T3/T4 and/or N+) were enrolled. After surgery, they were randomized into two groups: the CCRT group and the single chemotherapy group. Radiotherapy patients were treated according to the Intergroup 0116 guidelines. The chemotherapy consisted of continuously administered 5-fluorouracil (5-FU) and tetrahydrofolic acid (LV). The CCRT began 28 days after the first cycle of chemotherapy, and chemotherapy was given within the first four and last three days during the CCRT period, at a radiation dosage of 45 Gy/25 f, i.e., 1.8 Gy 5 times per week. Two cycles of the same chemotherapy were administrated 1 month after the radiotherapy. Five cycles of 5-FU and LV were applied to CG. RESULTS: One-, two-, and three-year survival rates were 85.9, 73.4, and 67.7%, respectively, in the CCRT group and 68.0, 50.0, and 44.1%, in the single chemotherapy group (P < 0.05). The corresponding disease-free survival rates were 73.5, 64.7, and 55.8% in the CCRT group and 61.8, 38.2, and 29.4% in the single chemotherapy group (P < 0.05). The major side effects were gastrointestinal reactions and neutrocytopenia. In both the CCRT and single chemotherapy groups, the incidence of these side effects was 73.5% (25/34) and 44.1% (15/34) (P < 0.05) for Grade I and Grade II anorexia, 82.35% (28/34) and 73.5% (25/34) (P > 0.05) for nausea and vomiting, and 70.6% (24/34) and 44.1% (15/34) (P < 0.05) for neutrocytopenia, respectively. The other indices showed no significant differences. CONCLUSIONS: Our findings indicate that CCRT can increase the one-, two-, and three-year total survival rates, as well as the disease-free survival rates of gastric cancer patients (T3/T4 and/or N+) who have been initially treated with surgery. The major adverse reactions were Grade I and Grade II nausea and vomiting, as well as myelosuppression. CCRT is well tolerated.

Folic acid and L-5-methyltetrahydrofolate: comparison of clinical pharmacokinetics and pharmacodynamics.

There is a large body of evidence to suggest that improving periconceptional folate status reduces the risk of neonatal neural tube defects. Thus increased folate intake is now recommended before and during the early stages of pregnancy, through folic acid supplements or fortified foods. Furthermore, there is growing evidence that folic acid may have a role in the prevention of other diseases, including dementia and certain types of cancer. Folic acid is a synthetic form of the vitamin, which is only found in fortified foods, supplements and pharmaceuticals. It lacks coenzyme activity and must be reduced to the metabolically active tetrahydrofolate form within the cell. L-5-methyl-tetrahydrofolate (L-5-methyl-THF) is the predominant form of dietary folate and the only species normally found in the circulation, and hence it is the folate that is normally transported into peripheral tissues to be used for cellular metabolism. L-5-methyl-THF is also available commercially as a crystalline form of the calcium salt (Metafolin(R)), which has the stability required for use as a supplement. Studies comparing L-5-methyl-THF and folic acid have found that the two compounds have comparable physiological activity, bioavailability and absorption at equimolar doses. Bioavailability studies have provided strong evidence that L-5-methyl-THF is at least as effective as folic acid in improving folate status, as measured by blood concentrations of folate and by functional indicators of folate status, such as plasma homocysteine. Intake of L-5-methyl-THF may have advantages over intake of folic acid. First, the potential for masking the haematological symptoms of vitamin B(12) deficiency may be reduced with L-5-methyl-THF. Second, L-5-methyl-THF may be associated with a reduced interaction with drugs that inhibit dihydrofolate reductase.

Phase I and pharmacokinetic study of LY309887: a specific inhibitor of purine biosynthesis.

PURPOSE: In this phase I trial in humans the safety and pharmacology of LY309887 on a weekly schedule combined with daily oral 5-mg doses of folic acid were evaluated. BACKGROUND: LY309887 is an inhibitor of folate-dependent enzymes involved in de novo purine biosynthesis and has a broad preclinical antitumor activity. In murine systems, combining this agent with exogenous folic acid results in an enhanced therapeutic index. METHODS: This study was a single-institution, open-label, clinical trial of dose escalation with toxicity and pharmacokinetic parameters determined. The dose range studied was 0.5-4 mg/m2 per week x6 and then a modified schedule weekly x3 every 6 weeks. RESULTS: Dose-limiting toxicities were of delayed onset and associated with hematologic, neurologic, and mucosal effects. Pharmacokinetic parameters revealed dose linearity for AUC and Cmax. Low circulating levels of drug persisted for over 200 h. Urinary excretion accounted for approximately 50% of the parent drug but was highly variable. The urinary excretion was near maximal within 24 h of dosing. CONCLUSIONS: The modified dosing schedule allowed repetitive dosing in patients. Further evaluation of the 2 mg/m2 per week x3 every 6 weeks with daily oral folate supplement as a potential phase II dose may be warranted.

Weekly lometrexol with daily oral folic acid is appropriate for phase II evaluation.

PURPOSE: Lometrexol [(6R)-5,10-dideaza-5,6,7,8-tetrahydrofolate] is the prototype folate antimetabolite that targets the de novo purine synthesis pathway. Early phase I trials were confounded by cumulative myelosuppression that prevented repetitive administration. Subsequent preclinical and clinical studies suggested that coadministration of folic acid might favorably modulate lometrexol toxicity without eliminating potential antitumor activity. We set out to determine if concurrent folic acid would allow administration of lometrexol on a weekly schedule, and, if so, to identify an appropriate dose combination for phase II trials. Pharmacokinetic and metabolism studies were undertaken in an attempt to improve our understanding of lometrexol pharmacodynamics. METHODS: Patients with advanced cancer received daily oral folic acid beginning 7 days before lometrexol and continuing for 7 days beyond the last lometrexol dose. Lometrexol was administered by short i.v. infusion weekly for 8 weeks. Scheduled lometrexol doses were omitted for toxicity of more than grade 2 present on the day of treatment, and dose-limiting toxicity was prospectively defined in terms of frequency of dose omission as well as the occurrence of severe toxic events. Plasma and whole blood total lometrexol contents (lometrexol plus lometrexol polyglutamates) were measured in samples taken just prior to each lometrexol dose. RESULTS: A total of 18 patients were treated at five lometrexol dose levels. The maximum tolerated dose was identified by frequent dose omission due to thrombocytopenia and mucositis. The recommended phase II dose combination is lometrexol 10.4 mg/m(2) per week i.v. with folic acid 3 mg/m(2) per day orally. One patient with melanoma experienced a partial response, and three patients, two with melanoma and one with renal cell carcinoma, experienced stable disease. Lometrexol was not detectable in any predose plasma sample tested. The total red blood cell content of lometrexol increased over several weeks and then appeared to plateau. CONCLUSIONS: Weekly administration of lometrexol is feasible and well-tolerated when coadministered with daily oral folic acid. The nature of the interaction between natural folates and lometrexol that renders this schedule feasible remains unclear. A definition of dose-limiting toxicity that incorporated attention to dose omissions allowed efficient identification of a recommended phase II dose that reflects the maximum feasible dose intensity for a weekly schedule. Lometrexol is a promising, anticancer agent.

Cellular but not plasma pharmacokinetics of lometrexol correlate with the occurrence of cumulative hematological toxicity.

Lometrexol inhibits the first folate-dependent enzyme in de novo purine biosynthesis and is avidly polyglutamated and retained in tissues expressing folylpolyglutamate synthetase. Although clinical studies have been limited by cumulative toxicity, preclinical studies show that pretreatment with folic acid can protect normal tissue while maintaining tumor cytotoxicity. Therefore, a Phase I study of lometrexol every 21 days preceded by i.v. folic acid was initiated. Lometrexol was studied in six patients at 15 mg/m2, in six patients at 20 mg/m2, in three patients at 25 mg/m2, and in nine patients at 30 mg/m2. Patients received either 5 mg of folic acid 1 h before or 25 mg/m2 3 h before lometrexol. Blood samples were obtained around the first course and weekly thereafter for determination of plasma and erythrocyte (RBC) lometrexol concentrations. Bioactive folates in plasma and RBCs were determined in a subset of patients. Lometrexol pharmacokinetics were best described by a three-compartment model. Mean clearance and volume of distribution were 1.6 +/- 0.6 liters/h/m2 and 8.9 +/- 4.1 liters/m2. Mean half-lives were 0.23 +/- 0.1, 2.9 +/- 1.4, and 25.0 +/- 48.7 h. Pharmacokinetics were independent of either lometrexol or folic acid dose. In the weekly blood samples, RBC lometrexol levels rose, long after plasma lometrexol was undetectable. RBC lometrexol levels were independent of folic acid or lometrexol dose. Bioactive folates measured in plasma and RBCs during this same time period did not accumulate. Rising RBC levels were correlated with a fall in hematocrit, hemoglobin, and platelet count. This study indicates that the cumulative toxicity of lometrexol is related to tissue concentration and not plasma pharmacokinetics. RBC lometrexol may be an indicator of cumulative drug exposure and effect.

Phase I study of the antipurine antifolate lometrexol (DDATHF) with folinic acid rescue.

Lometrexol (5,10-dideazatetrahydrofolic acid) is a new antifolate that is highly selective in inhibiting the key enzyme of purine synthesis glycinamide ribonucleotide formyltransferase. The most promising preclinical features of lometrexol in animal models were its significant activity against a broad panel of solid tumors, the schedule dependency of its antitumor activity, and the availability of a rescue regimen with folinic or folic acid. In the present study, lometrexol was first given daily for 3 consecutive days, repeated every 4 weeks (part I). The occurrence of delayed myelotoxicity prompted the development of a rescue regimen with lometrexol given in a single dose on day 1, followed by oral folinic acid, 15 mg four times a day, from day 3 to day 5 (part II). Longer time intervals between administration of lometrexol and start of rescue were then evaluated (part III), and in the last part of the study (part IV), the maximum tolerated dose of single intermittent doses of lometrexol with folinic acid given from day 7 to day 9 was established. Sixty adult patients entered the study. In part I, the highest daily dose that could be safely given was 4 mg/m2, for a total dose of 12 mg/m2. Cumulative early stomatitis and delayed thrombocytopenia were dose limiting. The use of oral folinic acid made it possible to escalate the dose up to 60 mg/m2, and the maximum tolerated dose was reached at this dose when folinic was given from day 7 to day 9, with anemia being the dose-limiting toxicity. A shorter time interval between lometrexol and folinic acid administrations (from day 5 to day 7) is recommended for Phase II evaluations to optimize the antitumor effect. Anemia was normochromic and macrocytic, possibly due to a deficiency of folic acid. One partial response of 8 months' duration was reported in a patient with epithelial cancer of the ovary, relapsing after cisplatin and alkylating agents. The use of folic acid as rescue, proposed on the basis of experimental data and pharmacological considerations, has also allowed the repeated administration of lometrexol at doses higher than in the previous studies. The advantages of rescue with folinic acid over supplementation with folic acid, however, are difficult to define.

A phase I clinical study of the antipurine antifolate lometrexol (DDATHF) given with oral folic acid.

Lometrexol is an antifolate which inhibits glycinamide ribonucleotide formyltransferase (GARFT), an enzyme essential for de novo purine synthesis. Extensive experimental and limited clinical data have shown that lometrexol has activity against tumours which are refractory to other drugs, notably methotrexate. However, the initial clinical development of lometrexol was curtailed because of severe and cumulative antiproliferative toxicities. Preclinical murine studies demonstrated that the toxicity of lometrexol can be prevented by low dose folic acid administration, i.e. for 7 days prior to and 7 days following a single bolus dose. This observation prompted a Phase I clinical study of lometrexol given with folic acid supplementation which has confirmed that the toxicity of lometrexol can be markedly reduced by folic acid supplementation. Thrombocytopenia and mucositis were the major toxicities. There was no clear relationship between clinical toxicity and the extent of plasma folate elevation. Associated studies demonstrated that lometrexol plasma pharmacokinetics were not altered by folic acid administration indicating that supplementation is unlikely to reduce toxicity by enhancing lometrexol plasma clearance. The work described in this report has identified for the first time a clinically acceptable schedule for the administration of a GARFT inhibitor. This information will facilitate the future evaluation of this class of compounds in cancer therapy.

Phase II trial of cisplatin, fluorouracil, and pure folinic acid for locally advanced head and neck cancer: a pharmacokinetic and clinical survey.

PURPOSE: To analyze clinical and pharmacokinetic data of cisplatin (CP)/fluorouracil (FU)/l folinic acid (l FA) chemotherapy administered as first-line treatment to locally advanced head and neck cancer patients. PATIENTS AND METHODS: Thirty-nine patients (35 men and four women; median age, 60 years; six stage III and 33 stage IV) received CP on day 1 (100 mg/m2) followed by l FA (200 mg/m2/d x 5) plus FU (500 mg/m2/d x 5) administered by continuous venous infusion (three cycles planned). Mean plasma concentrations of FU, l FA, and 5-methyltetrahydrofolate (5MTHF) over the cycle were computed. RESULTS: Clinical response was assessable for 33 patients. Response rates on the primary tumor site (n = 33) were 63.7% complete responses (CRs), 24.2% partial responses (PRs), and 12.1% treatment failures. Response rates on lymph nodes (n = 27) were 40.7% CRs, 37.1% PRs, and 22.2% treatment failures. The most frequent toxicity was mucositis (36.2% of cycles grade 3 to 4). Grade 3 to 4 nausea-vomiting, diarrhea, neutropenia, and thrombocytopenia occurred in 6.7%, 1.9%, 13.3%, and 1% of cycles, respectively. Pharmacokinetic analysis showed a wide interpatient variability for both FU (mean, 1.01 mumol/L; range, 0.16 to 2.09), l FA (mean, 1.89, mumol/L; range, 0.52 to 7.88) and 5MTHF plasma concentrations (mean, 3.85 mumol/L; range, 1.30 to 8.11). A significant correlation was demonstrated between FU concentration and hematologic toxicity grade, mucositis grade, and nausea-vomiting/diarrhea grade. Regarding tumor response, patients who failed to respond significantly exhibited lower FU and total folate concentrations than patients with a CR or PR. CONCLUSION: This study highlights the efficacy of CP/FU/l FA in head and neck carcinoma and establishes the clinical importance of coupled FU/FA pharmacokinetics to predict pharmacodynamic variability.

Phase I study of (6R)-5,10-dideazatetrahydrofolate: a folate antimetabolite inhibitory to de novo purine synthesis.

BACKGROUND: Cancer chemotherapy with folate antimetabolites has been traditionally targeted at the enzyme dihydrofolate reductase and is based on the requirement of dividing tumor cells for a supply of thymidylate and purines. However, a new compound, 5,10-dideazatetrahydrofolate (DDATHF, whose 6R diastereomer is also known as Lometrexol), has become available that prevents tumor cell growth by inhibiting the first of the folate-dependent enzymes involved in de novo purine synthesis, glycinamide ribonucleotide formyltransferase. PURPOSE: We investigated the toxicity and therapeutic activity of DDATHF in a phase I clinical trial. METHODS: DDATHF was given at one of the following dose levels to 33 patients (16 females and 17 males) with malignant solid tumors: 3.0 mg/m2 per week (level A) to 10 patients, 4.5 mg/m2 per week (level B) to 13 patients, or 6.0 mg/m2 per week (level C) to 10 patients. Each drug cycle consisted of three weekly injections of DDATHF followed by a 2-week rest prior to redosing in the next cycle. RESULTS: Of 33 patients, 27 received at least one full cycle of DDATHF. Thrombocytopenia was the major dose-limiting toxicity, and it was severe in one of 10 patients during the first cycle and in two of four patients during the second cycle. Because of cumulative toxicity at 6.0 mg/m2, second or later cycles were abbreviated to two weekly doses. Stomatitis was generally mild, but it was dose-limiting in one patient. Neutropenia was infrequent and mild, and normocytic anemia requiring blood transfusion was common with repeat dosing. Leucovorin was given for grade 2 or greater thrombocytopenia and resulted in hematologic recovery within 1 week in all eight patients so treated. Without leucovorin, the thrombocytopenia lasted from 7 to 49 days in three patients. A partial response was noted in one patient with non-small-cell lung cancer and a minor response in one patient with breast cancer. Three patients with colorectal cancer achieved stable disease for greater than 3 months with improvement in carcinoembryonic antigen levels in one patient. CONCLUSIONS: DDATHF has an unusual pattern of toxicity with repetitive dosing, and humans with advanced cancer are considerably more sensitive than would be predicted from previous animal studies. Although doses of 6.0 mg/m2 per week on our schedule have been determined to be safe, repeated cycles require careful monitoring because of cumulative toxic effects. IMPLICATIONS: Additional phase I studies of DDATHF that relate toxicity to folate intake and tissue folate pools appear warranted.

An open trial of methyltetrahydrofolate in elderly depressed patients.

5-methyltetrahydrofolate (MTHF) is a naturally occurring substance involved in the synthesis of s-adenosyl-l-methionine (SAMe), a major source of methyl groups in the brain. To assess the efficacy of a gastro-resistant, oral preparation of MTHF, 20 elderly patients with a DSM-III-R diagnosis of depressive disorder and a HAM-D-21 score > or = 18 underwent 6-weeks of open-label treatment with 50 mg per day of oral MTHF. Of these 20 patients, 16 completed at least 4 weeks of treatment and showed a markedly significant improvement in their depressive symptoms at endpoint, with 81% of them being considered responders. There were no clinically relevant changes in the routine laboratory tests during the study, and no adverse events considered to be definitely drug-related were reported.