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

Lookup NU author(s): Professor Steve Wedge, Fiona Chapman, Gordon Taylor, Huw ThomasORCiD, Professor Alan Boddy, Professor Herbie Newell, Professor Alan Calvert


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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.

Publication metadata

Author(s): Laohavinij S, Wedge S, Lind M, Bailey N, Humphreys A, Proctor M, Chapman F, Simmons D, Oakley A, Robson L, Gumbrell L, Taylor G, Thomas HD, Boddy AV, Newell DR, Calvert AH

Publication type: Article

Publication status: Published

Journal: Investigational New Drugs

Year: 1996

Volume: 14

Issue: 3

Pages: 325-335

Print publication date: 01/09/1996

ISSN (print): 0167-6997

ISSN (electronic): 1573-0646


DOI: 10.1007/BF00194536

PubMed id: 8958188


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