High-Dose Methotrexate-Leucovorin Rescue Therapy: Selected Application in Non-Hodgkin's Lymphoma

Overview of Dual-Acting Drug Methotrexate in Different Neurological Diseases, Autoimmune Pathologies and Cancers

Methotrexate, a structural analogue of folic acid, is one of the most effective and extensively used drugs for treating many kinds of cancer or severe and resistant forms of autoimmune diseases. In this paper, we take an overview of the present state of knowledge with regards to complex mechanisms of methotrexate action and its applications as immunosuppressive drug or chemotherapeutic agent in oncological combination therapy. In addition, the issue of the potential benefits of methotrexate in the development of neurological disorders in Alzheimer’s disease or myasthenia gravis will be discussed.

Dose-dependent disposition of methotrexate in Abcc2 and Abcc3 gene knockout murine models

Methotrexate (MTX) is a substrate for numerous human ATP-binding cassette (ABC) efflux transporters, yet the impact of these transporters on MTX pharmacokinetics (PK) over a large dose range has not been examined. To investigate the effects of two transporters-ABC subfamily C member 2 (Abcc2; multidrug resistance protein 2) and ABC subfamily C member 3 (Abcc3; multidrug resistance protein 3)-involved in MTX hepatobiliary disposition in vivo, MTX plasma, urine, and feces concentrations were analyzed after 10, 50, and 200 mg/kg i.v. doses to groups of wild type (WT), Abcc2(-/-), and Abcc3(-/-) mice. The absence of Abcc2 caused a decrease in total clearance of MTX relative to WT mice at all dose levels yet was accompanied by compensatory increases in renal excretion and metabolism to 7-hydroxymethotrexate (7OH-MTX). In Abcc3(-/-) mice, total clearance was elevated at the two lower dose levels and was attributed to stimulation of biliary excretion and confirmed by elevated fecal excretion; however, at the high 200 mg/kg dose, clearance was severely retarded and could be attributed to hepatotoxicity because conversion to 7OH-MTX was diminished. The findings confirmed that both Abcc2 and Abcc3 significantly influenced the PK properties of MTX, and depending on the MTX dose and strain, alternate elimination pathways were elicited and saturable.

Alleviation by leucovorin of the dose-limiting toxicity of edatrexate: potential for improved therapeutic efficacy

Edatrexate (10-ethyl-10-deaza-aminopterin; CGP 30 694) is a methotrexate (MTX) analogue that shows promise against non-small-cell lung cancer (NSCLC) and other tumors. Since edatrexate's mechanism of action is the same as that of MTX, we used leucovorin in an attempt to alleviate its dose-limiting toxicity, stomatitis. In four patients with NSCLC who had experienced significant stomatitis after treatment with edatrexate, cyclophosphamide, and cisplatin, we observed a remarkable reduction in stomatitis following the administration of low-dose leucovorin. On the basis of the results obtained in these individuals, we treated 15 additional patients with this three-drug regimen plus leucovorin rescue. These subjects could tolerate the treatment with lesser degrees of stomatitis and received higher edatrexate doses in subsequent courses as compared with the patients who previously received this regimen without leucovorin rescue. This approach is expected to improve the therapeutic indices of edatrexate and edatrexate-containing chemotherapy regimens by modifying the dose-limiting toxicity of this antineoplastic agent.

A randomized comparison of methotrexate dose and the addition of bleomycin to CHOP therapy for diffuse large cell lymphoma and other non-Hodgkin's lymphomas. Cancer and Leukemia Group B study 7851

In 1978, Cancer and Leukemia Group B initiated a randomized study to determine the usefulness of the addition of bleomycin and/or high-dose methotrexate to standard therapy for the treatment of certain adult non-Hodgkin's lymphomas. Between 1978 and 1985, 177 patients with diffuse large cell lymphoma (DLCL) and 97 patients with other intermediate-grade non-Hodgkin's lymphoma were randomized to receive therapy with three courses of cyclophosphamide, adriamycin, vincristine, and prednisone (CHOP) every 3 weeks with or without low-dose bleomycin by continuous IV infusion. Responders after three courses were further randomized to 3 weeks of therapy with either high-dose methotrexate (3 gm/m2/week intravenously with leucovorin rescue) or standard-dose methotrexate (30 mg/m2/week orally without rescue). Therapy was concluded with three additional courses of CHOP. Neither the addition of low-dose infusion bleomycin nor the use of high-dose rather than low-dose methotrexate had significant effects on response for patients with DLCL; complete response rates for the four treatment programs ranged from 47% to 51%. Median failure-free survival (FFS) for the entire group of DLCL patients was 12 months; 5-year FFS was 27%. There was no significant effect on FFS from the addition of either low-dose bleomycin to CHOP (5-year FFS: CHOP, 28%; CHOP-B, 26%, P = 0.81), or from the use of different doses of methotrexate (5-year FFS: high-dose, 34%; standard-dose, 33%, P = 0.51). Patients with follicular large cell lymphoma, with or without diffuse areas, had a better FFS (5-year FFS, 47%) than patients with DLCL (5-year FFS, 27%), while the patients with the other histopathologic subtypes of diffuse lymphomas had the poorest FFS (5-year FFS, 16%).