UNBS3157 is a novel naphthalimide derivative that is non-hematotoxic and exhibits significant antitumor activity through DNA intercalation and the poisoning of topoisomerase IIalpha. Unlike Amonafide, a related naphthalimide compound that showed activity in Phase II breast cancer trials but did not proceed to Phase III due to dose-limiting myelotoxicity, UNBS3157 has a maximum tolerated dose 3-4 times higher and does not cause hematotoxicity in mice at effective antitumor doses. In vivo models, including (i) L1210 mouse leukemia, (ii) MXT-HI mouse mammary adenocarcinoma, and (iii) human A549 non-small cell lung carcinoma and BxPC3 pancreatic cancer orthotopic models, demonstrate superior efficacy of UNBS3157 compared to Amonafide.