The antitumor activities of twelve 2-N-and/or 5-substituted 2-amino-1, 3, 4-thiadiazole analogs were tested on Lewis lung carcinoma in mice by intraperitoneal administration. 2-Amino-1, 3, 4-thiadiazole (ATDA), 2-formamido-1, 3, 4-thiadiazole and 2-trifluoroacetamido-1, 3, 4-thiadiazole significantly prolonged the life span of tumor bearing mice. 5-Substituted analogs and 2-urethane and 2-carbamate type compounds were inactive. 2-Formamido-1, 3, 4-thiadiazole showed more potent activity than the parent compound ATDA against P388, L1210 leukemia, B16 melanoma and Lewis lung carcinoma. The differences in the antitumor activity among ATDA analogs are discussed.
