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Bulletin Du Cancer Nov 2011Antimetabolites are cytotoxic agents, which have been developed for more than 50 years. Which cancer patient did not receive or will not receive 5-fluorouracil or... (Review)
Review
Antimetabolites are cytotoxic agents, which have been developed for more than 50 years. Which cancer patient did not receive or will not receive 5-fluorouracil or methotrexate during the evolution his or her disease? Antimetabolites are defined as interfering with the synthesis of the DNA constituents; they are structural analogues, either of purine and pyrimidine bases (or the corresponding nucleosides), or of folate cofactors, which are involved at several steps of purine and pyrimidine biosynthesis. Their first mechanism of action is, therefore, to induce depletion in nucleotides inducing in turn an inhibition of DNA replication. However, some of them are able to get inserted fraudulently into nucleic acids, inducing structural abnormalities leading to cell death by other mechanisms, including DNA breaks. We present in this paper, for the three classes of antimetabolites, both ancient and recent molecules as well as molecules still in clinical trials, without exhaustivity.
Topics: Antimetabolites, Antineoplastic; DNA Replication; Folic Acid Antagonists; Humans; Leukemia; Neoplasms; Purines; Pyrimidines
PubMed: 22049385
DOI: 10.1684/bdc.2011.1476 -
Rheumatic Diseases Clinics of North... Nov 1997Because of methotrexate's well-documented efficacy in the treatment of rheumatoid arthritis, it is important that we understand the mechanism of action of this drug.... (Review)
Review
Because of methotrexate's well-documented efficacy in the treatment of rheumatoid arthritis, it is important that we understand the mechanism of action of this drug. There are two biochemical mechanisms by which methotrexate may modulate inflammation: (1) promotion of adenosine release and (2) inhibition of transmethylation reactions. Evidence is reviewed that favors the notion that the endogenous anti-inflammatory autocoid adenosine mediates the anti-inflammatory effects of methotrexate. This insight should aid in the design of new agents for the treatment of rheumatoid arthritis and other inflammatory diseases.
Topics: Adenosine; Animals; Anti-Inflammatory Agents; Antirheumatic Agents; Arthritis, Rheumatoid; Enzyme Inhibitors; Folic Acid Antagonists; Humans; Methotrexate; Methylation
PubMed: 9361153
DOI: 10.1016/s0889-857x(05)70358-6 -
The Cochrane Database of Systematic... May 2013Methotrexate (MTX) is a disease modifying antirheumatic drug (DMARD) used as a first line agent for treating rheumatoid arthritis (RA). Pharmacologically, it is... (Review)
Review
BACKGROUND
Methotrexate (MTX) is a disease modifying antirheumatic drug (DMARD) used as a first line agent for treating rheumatoid arthritis (RA). Pharmacologically, it is classified as an antimetabolite due to its antagonistic effect on folic acid metabolism. Many patients treated with MTX experience mucosal, gastrointestinal, hepatic or haematologic side effects. Supplementation with folic or folinic acid during treatment with MTX may ameliorate these side effects.
OBJECTIVES
To identify trials of supplementation with folic acid or folinic acid during MTX therapy for rheumatoid arthritis and to assess the benefits and harms of folic acid and folinic acid (a) in reducing the mucosal, gastrointestinal (GI), hepatic and haematologic side effects of MTX, and (b) whether or not folic or folinic acid supplementation has any effect on MTX benefit.
SEARCH METHODS
We originally performed MEDLINE searches, from January 1966 to June 1999. During the update of this review, we searched additional databases and used a sensitive search strategy designed to retrieve all trials on folic acid or folinic acid for rheumatoid arthritis from 1999 up to 2 March 2012.
SELECTION CRITERIA
We selected all double-blind, randomised, placebo-controlled clinical trials (RCTs) in which adult patients with rheumatoid arthritis were treated with MTX (at a dose equal to or less than 25 mg/week) concurrently with folate supplementation. In this update of the review we only included trials using 'low dose' folic or folinic acid (a starting dose of ≤ 7 mg weekly).
DATA COLLECTION AND ANALYSIS
Data were extracted from the trials, and the trials were independently assessed for risk of bias using a predetermined set of criteria.
MAIN RESULTS
Six trials with 624 patients were eligible for inclusion. Most studies had low or unclear risk of bias for key domains. The quality of the evidence was rated as 'moderate' for each outcome as assessed by GRADE, with the exception of haematologic side effects which were rated as 'low'. There was no significant heterogeneity between trials, including where folic acid and folinic acid studies were pooled.For patients supplemented with any form of exogenous folate (either folic or folinic acid) whilst on MTX therapy for rheumatoid arthritis, a 26% relative (9% absolute) risk reduction was seen for the incidence of GI side effects such as nausea, vomiting or abdominal pain (RR 0.74, 95% CI 0.59 to 0.92; P = 0.008). Folic and folinic acid also appear to be protective against abnormal serum transaminase elevation caused by MTX, with a 76.9% relative (16% absolute) risk reduction (RR 0.23, 95% CI 0.15 to 0.34; P < 0.00001), as well as reducing patient withdrawal from MTX for any reason (60.8% relative (15.2% absolute) risk reduction, RR 0.39, 95% CI 0.28 to 0.53; P < 0.00001).We analysed the effect of folic or folinic acid on the incidence of stomatitis / mouth sores, and whilst showing a trend towards reduction in risk, the results were not statistically significant (RR 0.72, 95% CI 0.49 to 1.06)It was not possible to draw meaningful conclusions on the effect of folic or folinic acid on haematologic side effects of methotrexate due to small numbers of events and poor reporting of this outcome in included trials.It does not appear that supplementation with either folic or folinic acid has a statistically significant effect on the efficacy of MTX in treating RA (as measured by RA disease activity parameters such as tender and swollen joint counts, or physician's global assessment scores).
AUTHORS' CONCLUSIONS
The results support a protective effect of supplementation with either folic or folinic acid for patients with rheumatoid arthritis during treatment with MTX.There was a significant reduction shown in the incidence of GI side effects, hepatic dysfunction (asmeasured by elevated serum transaminase levels) as well as a significant reduction in discontinuation of MTX treatment for any reason. A trend towards a reduction in stomatitis was demonstrated however this did not reach statistical significance.This updated review with its focus on lower doses of folic acid and folinic acid and updated assessment of risk of bias aimed to give a more precise and more clinically relevant estimate of the benefit of folate supplementation for patients with rheumatoid arthritis receiving methotrexate.
Topics: Abdominal Pain; Adult; Antirheumatic Agents; Arthritis, Rheumatoid; Folic Acid; Folic Acid Antagonists; Gastrointestinal Diseases; Hematologic Diseases; Humans; Leucovorin; Methotrexate; Nausea; Vomiting
PubMed: 23728635
DOI: 10.1002/14651858.CD000951.pub2 -
Hematology/oncology Clinics of North... Jun 2012This article focuses on the cellular, biochemical, and molecular pharmacology of antifolates and how a basic understanding of the mechanism of action of methotrexate,... (Review)
Review
This article focuses on the cellular, biochemical, and molecular pharmacology of antifolates and how a basic understanding of the mechanism of action of methotrexate, its cytotoxic determinants, mechanisms of resistance, and transport into and out of cells has led to the development of a new generation of antifolates, a process that continues in the laboratory and in the clinics. New approaches to folate-based cancer chemotherapy are described based on the targeted delivery of drugs to malignant cells.
Topics: Animals; Antimetabolites, Antineoplastic; Drug Resistance, Neoplasm; Folic Acid; Folic Acid Antagonists; Humans; Methotrexate; Molecular Targeted Therapy; Neoplasms
PubMed: 22520983
DOI: 10.1016/j.hoc.2012.02.002 -
Dermatologic Clinics Oct 2015This article reviews methotrexate and the more potent, related compound, pralatrexate, for the treatment of cutaneous T-cell lymphomas, including mycosis fungoides,... (Review)
Review
This article reviews methotrexate and the more potent, related compound, pralatrexate, for the treatment of cutaneous T-cell lymphomas, including mycosis fungoides, Sézary syndrome, and CD30+ lymphoproliferative disorders. Although these folate antagonists are traditionally viewed as antiproliferative cell cycle inhibitors, it is recognized that they inhibit DNA methylation, providing a rationale for their use as epigenetic regulators and cell proliferation inhibitors. The underlying mechanisms are outlined, key supporting data presented, followed by brief mention of recent mathematical modeling supporting the general superiority of combination therapy. Several novel examples involving folate antagonists are proposed.
Topics: Aminopterin; Antimetabolites, Antineoplastic; Apoptosis; DNA Methylation; Epigenesis, Genetic; Folic Acid Antagonists; Humans; Lymphoma, T-Cell, Cutaneous; Methotrexate; S Phase; Skin Neoplasms
PubMed: 26433846
DOI: 10.1016/j.det.2015.05.009 -
Leukemia Jun 2021Folate-mediated one carbon (1C) metabolism supports a series of processes that are essential for the cell. Through a number of interlinked reactions happening in the... (Review)
Review
Folate-mediated one carbon (1C) metabolism supports a series of processes that are essential for the cell. Through a number of interlinked reactions happening in the cytosol and mitochondria of the cell, folate metabolism contributes to de novo purine and thymidylate synthesis, to the methionine cycle and redox defence. Targeting the folate metabolism gave rise to modern chemotherapy, through the introduction of antifolates to treat paediatric leukaemia. Since then, antifolates, such as methotrexate and pralatrexate have been used to treat a series of blood cancers in clinic. However, traditional antifolates have many deleterious side effects in normal proliferating tissue, highlighting the urgent need for novel strategies to more selectively target 1C metabolism. Notably, mitochondrial 1C enzymes have been shown to be significantly upregulated in various cancers, making them attractive targets for the development of new chemotherapeutic agents. In this article, we present a detailed overview of folate-mediated 1C metabolism, its importance on cellular level and discuss how targeting folate metabolism has been exploited in blood cancers. Additionally, we explore possible therapeutic strategies that could overcome the limitations of traditional antifolates.
Topics: Animals; Antineoplastic Agents; Carbon; Folic Acid; Folic Acid Antagonists; Hematologic Neoplasms; Humans
PubMed: 33707653
DOI: 10.1038/s41375-021-01189-2 -
Current Opinion in Structural Biology Jun 2022Structural studies on mammalian vitamin transport lag behind other metabolites. Folates, also known as B9 vitamins, are essential cofactors in one-carbon transfer... (Review)
Review
Structural studies on mammalian vitamin transport lag behind other metabolites. Folates, also known as B9 vitamins, are essential cofactors in one-carbon transfer reactions in biology. Three different systems control folate uptake in the human body; folate receptors function to capture and internalise extracellular folates via endocytosis, whereas two major facilitator superfamily transporters, the reduced folate carrier (RFC; SLC19A1) and proton-coupled folate transporter (PCFT; SLC46A1) control the transport of folates across cellular membranes. Targeting specific folate transporters is being pursued as a route to developing new antifolates with improved pharmacology. Recent structures of the proton-coupled folate transporter, PCFT, revealed key insights into antifolate recognition and the mechanism of proton-coupled transport. Combined with previously determined structures of folate receptors and new predictions for the structure of the RFC, we are now able to develop a structure-based understanding of folate and antifolate recognition to accelerate efforts in antifolate drug development.
Topics: Animals; Biological Transport; Cell Membrane; Folic Acid; Folic Acid Antagonists; Humans; Mammals; Proton-Coupled Folate Transporter
PubMed: 35303537
DOI: 10.1016/j.sbi.2022.102353 -
Nature Sep 2022Folates are essential nutrients with important roles as cofactors in one-carbon transfer reactions, being heavily utilized in the synthesis of nucleic acids and the...
Folates are essential nutrients with important roles as cofactors in one-carbon transfer reactions, being heavily utilized in the synthesis of nucleic acids and the metabolism of amino acids during cell division. Mammals lack de novo folate synthesis pathways and thus rely on folate uptake from the extracellular milieu. The human reduced folate carrier (hRFC, also known as SLC19A1) is the major importer of folates into the cell, as well as chemotherapeutic agents such as methotrexate. As an anion exchanger, RFC couples the import of folates and antifolates to anion export across the cell membrane and it is a major determinant in methotrexate (antifolate) sensitivity, as genetic variants and its depletion result in drug resistance. Despite its importance, the molecular basis of substrate specificity by hRFC remains unclear. Here we present cryo-electron microscopy structures of hRFC in the apo state and captured in complex with methotrexate. Combined with molecular dynamics simulations and functional experiments, our study uncovers key determinants of hRFC transport selectivity among folates and antifolate drugs while shedding light on important features of anion recognition by hRFC.
Topics: Anions; Apoproteins; Biological Transport; Carbon; Cryoelectron Microscopy; Folic Acid; Folic Acid Antagonists; Humans; Methotrexate; Molecular Dynamics Simulation; Reduced Folate Carrier Protein; Substrate Specificity
PubMed: 36071163
DOI: 10.1038/s41586-022-05168-0 -
Frontiers in Immunology 2022Non-invasive imaging modalities constitute an increasingly important tool in diagnostic and therapy response monitoring of patients with autoimmune diseases, including... (Review)
Review
Non-invasive imaging modalities constitute an increasingly important tool in diagnostic and therapy response monitoring of patients with autoimmune diseases, including rheumatoid arthritis (RA). In particular, macrophage imaging with positron emission tomography (PET) using novel radiotracers based on differential expression of plasma membrane proteins and functioning of cellular processes may be suited for this. Over the past decade, selective expression of folate receptor β (FRβ), a glycosylphosphatidylinositol-anchored plasma membrane protein, on myeloid cells has emerged as an attractive target for macrophage imaging by exploiting the high binding affinity of folate-based PET tracers. This work discusses molecular, biochemical and functional properties of FRβ, describes the preclinical development of a folate-PET tracer and the evaluation of this tracer in a translational model of arthritis for diagnostics and therapy-response monitoring, and finally the first clinical application of the folate-PET tracer in RA patients with active disease. Consequently, folate-based PET tracers hold great promise for macrophage imaging in a variety of (chronic) inflammatory (autoimmune) diseases beyond RA.
Topics: Animals; Arthritis, Rheumatoid; Folate Receptor 2; Folic Acid; Folic Acid Antagonists; Humans; Macrophages; Positron-Emission Tomography
PubMed: 35185910
DOI: 10.3389/fimmu.2022.819163 -
Current Problems in Cancer Feb 2023Folate is a B vitamin necessary for basic biological functions, including rapid cell turnover occurring in cancer cell proliferation. Though the role of folate as a... (Review)
Review
Folate is a B vitamin necessary for basic biological functions, including rapid cell turnover occurring in cancer cell proliferation. Though the role of folate as a causative versus protective agent in carcinogenesis is debated, several studies have indicated that the folate receptor (FR), notably subtype folate receptor alpha (FRα), could be a viable biomarker for diagnosis, progression, and prognosis. Several cancers, including gastrointestinal, gynecological, breast, lung, and squamous cell head and neck cancers overexpress FR and are currently under investigation to correlate receptor status to disease state. Traditional chemotherapies have included antifolate medications, such as methotrexate and pemetrexed, which generate anticancer activity during the synthesis phase of the cell cycle. Increasingly, the repertoire of pharmacotherapies is expanding to include FR as a target, with a heterogenous pool of directed therapies. Here we discuss the FR, expression and effect in cancer biology, and relevant pharmacologic inhibitors.
Topics: Humans; Folic Acid Antagonists; Prognosis; Carcinoma, Squamous Cell; Folic Acid; Biomarkers
PubMed: 36508886
DOI: 10.1016/j.currproblcancer.2022.100917