Document Detail

Phase I study of (6R)-5,10-dideazatetrahydrofolate: a folate antimetabolite inhibitory to de novo purine synthesis.
MedLine Citation:
PMID:  8320744     Owner:  NLM     Status:  MEDLINE    
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.
M S Ray; F M Muggia; C G Leichman; S M Grunberg; R L Nelson; R W Dyke; R G Moran
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Publication Detail:
Type:  Clinical Trial; Clinical Trial, Phase I; Controlled Clinical Trial; Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of the National Cancer Institute     Volume:  85     ISSN:  0027-8874     ISO Abbreviation:  J. Natl. Cancer Inst.     Publication Date:  1993 Jul 
Date Detail:
Created Date:  1993-08-05     Completed Date:  1993-08-05     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  7503089     Medline TA:  J Natl Cancer Inst     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1154-9     Citation Subset:  IM    
Department of Medicine, University of Southern California, Los Angeles.
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MeSH Terms
Drug Administration Schedule
Folic Acid Antagonists / administration & dosage,  adverse effects,  therapeutic use*
Hematologic Diseases / chemically induced,  drug therapy
Leucovorin / therapeutic use
Middle Aged
Neoplasms / drug therapy
Purines / metabolism
Tetrahydrofolates / administration & dosage,  adverse effects,  therapeutic use*
Treatment Outcome
Grant Support
Reg. No./Substance:
0/Folic Acid Antagonists; 0/Purines; 0/Tetrahydrofolates; 58-05-9/Leucovorin; 95693-76-8/lometrexol

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