An antifolate with anticancer activity; an inhibitor of thymidylate synthase and dihydrofolate reductase (Kis = 109 and 7 nM, respectively); has increased potency for thymidylate kinase when polyglutaminated (Ki = 1.3 nM); an inhibitor of glycinamide ribonucleotide formyltransferase (Kis = 9,300 and 65 nM for the non-glutaminated and polyglutaminated enzyme) and aminoimidazole carboxamide ribonucleotide formyltransferase (Kis = 3,600 and 265 nM for the non-glutaminated and polyglutaminated, respectively); inhibits proliferation of CCRF-CEM cells but not 5,10-dideazatetrahydrofolate-resistant CR15 cells (IC50s = 0.254 and 200 µM, respectively); reduces tumor growth in A549, H1299, and PC-9 NSCLC mouse xenograft models but not in models using the same cell lines overexpressing thymidylate kinase