Abstract Chemotherapy drugs for the treatment of cancer are generally directed to inhibit the reproduction of malignant cells and killing cells, thereby preventing tumor growth or reducing tumor size. Many of these drugs develop resistance to tumor cells by different mechanisms. Therefore a significant clinical need exists for the development of additional chemotherapeutic agents that are toxic to a wide range of tumor cells, in particular tumors that are resistant to current treatments such as radiotherapy and chemotherapy. From recent past, it has been known that barbituric acid derivatives exhibit different biological activities such as anti-depressant, anti-convulsant, anti-viral and anti-cancer activities. Among them some thiobarbituric acid derivatives, such as merocyanine and merbarone have been proposed as possible modulators of apoptosis in several cancer cells including glioblastoma multiforme (GBM), lung, melanoma, leukemia, breast cancer, prostate cancer, and cervical cancer; albeit not particularly for cancers that are resistant to current therapy. We designed and synthesized novel thio- and seleno- barbituric derivatives by varying the substituents at N1, N3 (ethyl, methyl, allyl, and phenyl) and C5 tethered with dienyl and trienyl moieties attached with different substituents like phenyl, 2-furanyl, 2-thiophenyl, 1-naphthyl & 3-pyridyl. These compounds were tested against both chemotherapy sensitive and resistant, melanoma (UACC903 and CHL-1), GBM (U87-MG, T98G, and CCF-STTG1) , and lung cancer (A549, H460, H520and H69) cells. Most of these compounds reduced cell viability in a dose and time dependent manner. Among all the compounds ASR-198, ASR-199, ASR-243 and ASR-244 were most cytotoxic to both chemotherapy resistant and sensitive cells. In addition, these compounds triggered a dose dependent induction of apoptosis by activation of caspase-3 and PARP cleavage in melanoma cells. Overall compound ASR-198, having a 2-thiophen-dienyl substitution and C-5 position, emerged as the most efficacious compound in all three cancer cell lines. Interestingly its isosteric selenium analogs were relatively less cytotoxic. In summary, this structure-activity relationship study clearly indicates that more efficacious compounds, compared to existing thiobarbituric analogs, can be developed based on barbituric acid scaffold, by rational modifications of the chemo type compounds. Detailed results of these investigations will be presented. Citation Format: Srinivasa R. Ramisetti, Sang Y. Lee, Manoj K. Pandey, Shantu G. Amin, Arun K. Sharma. Development of novel thiobarbituric acid derivatives as potential cancer therapeutics. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1639. doi:10.1158/1538-7445.AM2014-1639