Methods Used for Biological Testing. The antitumor data on compound 1 (NSC 313384) were collected at Arthur D. Little, Inc., Boston, MA, under the auspices of the National Cancer Institute using the standard protocol for evaluating (Instruction 14) methotrexate analogues in the L-1210 leukemia test system. Dihydrofolate reducta~ e,~~ thymidylate synthase, z4 and microbiological assaysz5 were carried out as described previously.'