title: Substitution of l-leucovorin for d,l-leucovorin in the rescue from high-dose methotrexate treatment in patients with osteosarcoma.
abstract: Studies in which high-dose methotrexate (HDMTX) is used for the treatment of osteosarcoma have utilized commercial formulations of d,l-leucovorin (leucovorin calcium) for rescue from potential methotrexate (MTX) toxicity. These formulations are racemic mixtures containing equal amounts of d and l isomers of leucovorin. All of the available data indicate that the l isomer is the pharmacologically active diastereomer. A clinical study was conducted to determine if l-leucovorin was as safe and efficacious as d,l-leucovorin in the rescue of patients with osteosarcoma who were treated with HDMTX (12.5 g/m2 over 6 h). Because d,l-leucovorin consists of equal proportions of d and l isomers, l-leucovorin was administered at half the usual dose of d,l-leucovorin. In patients with delayed methotrexate excretion, l-leucovorin doses were escalated from 7.5 to 50 mg every 3 h until the MTX level was 0.3 mumol/l or less. Due to the low incidence of osteosarcoma, a control group of patients previously treated with d,l-leucovorin was utilized for comparison. Efficacy of l-leucovorin was determined by its ability to prevent HDMTX-associated toxicity. Demographic and clinical toxicity data from three patients who received 22 courses of MTX rescued with l-leucovorin were compared with data from six patients who had received 42 MTX courses rescued with d,l-leucovorin. Some liver function abnormalities and leukocyte elevations were found in both groups and were attributed to MTX administration. No clinical toxicity attributable to l-leucovorin was observed. l-Leucovorin in half the d,l-leucovorin dose was (equally) effective as a rescue treatment.
authors.affiliation: University of Texas MD Anderson Cancer Center, Houston 77030.
authors.forename: N
authors.initials: N
authors.lastname: Jaffe
authors.forename: K
authors.initials: K
authors.lastname: Jorgensen
authors.forename: R
authors.initials: R
authors.lastname: Robertson
authors.forename: M
authors.initials: M
authors.lastname: George
authors.forename: L
authors.initials: L
authors.lastname: Letvak
authors.forename: G
authors.initials: G
authors.lastname: Barrett
mesh_terms: D000293:Adolescent; D001859:Bone Neoplasms / Q000188:drug therapy*; D002648:Child; D004334:Drug Administration Schedule; D006801:Humans; D007677:Kidney Function Tests; D002955:Leucovorin / Q000009:adverse effects / Q000627:therapeutic use*; D007958:Leukocyte Count; D008111:Liver Function Tests; D008727:Methotrexate / Q000009:adverse effects* / Q000493:pharmacokinetics / Q000627:therapeutic use; D012516:Osteosarcoma / Q000188:drug therapy*; D012189:Retrospective Studies; D013237:Stereoisomerism
chemical_list: D002955:Leucovorin; D008727:Methotrexate