Potentiation of the Anti-leukemic Effects of 2-Aminothiadiazole by Isonicotinamide and Derivatives

Isonicotinamide (INAM), 6-aminopicolinamide, and several related nicotinamide analogs have been demonstrated to enhance the activity of 2-amino-1,3,4-thiadiazole (ATDA) against transplanted mouse leukemias. The combinations were effective only against those leukemias which also responded to ATDA alone. The potentiation of therapeutic effect was paralleled by potentiation of the degree of host toxicity. Both nicotinamide and nicotinic acid blocked the anti-leukemic activity of ATDA in combination with INAM. Neither isonicotinic acid nor 6-aminopicolinic acid enhanced the anti-leukemic activity of ATDA.