Abstract LB-353: Development of thymidylate synthase ternary complex-specific antibody: A new way to tailor 5-fluorouracil dosing

Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL Introduction: 5-Fluorouracil (5FU) is a fluorinated nucleoside analogue used in cancer treatment. 5FU metabolites modify thymidylate synthase (TS) to form a ternary complex and inhibit its activity. Despite its benefits, major side effects are common and can lead to discontinuation of 5FU therapy. Although dose, schedule, and mode of application of 5FU can be adjusted to minimize toxicity, there has been a little done to tailor 5FU dosage for cancer therapy. Aims: To develop a ternary complex-specific monoclonal antibody. To develop a test quantifying drug-complexed TS level so as to measure the action of 5FU at the cellular level. Methods: Recombinant TS was produced in E. coli. In-vitro, the ternary complex was created. A specific rat monoclonal antibody was raised against drug-complexed TS. ELISA and immunoblot (IB) assays were validated using 5FU-treated cells. Tumors were developed in nude mice by injection of RKO and MiaPaCa2 cells. We treated tumors in mice with 5FU at different doses and assayed the tumor upon harvest. Results: The drug-complexed TS migrates slower than native TS in protein gels. Our novel ternary complex-specific rat monoclonal antibody (10C4) specifically recognized drug-complexed TS in ELISA and IB in both cultured cells and tumors treated with 5FU. Commercially available TS-specific antibody recognized both forms of TS. Conclusion: We developed and characterized the first thymidylate synthase ternary complex-specific rat monoclonal antibody. Implications: Quantification of drug-complexed TS may be possible with use of the new antibody. The actual action of 5FU at the cellular level can now be determined readily. It may become possible to calculate individualized 5FU doses in the clinic using advances in the technology. Such developments might decrease the incidence of toxicity and increase drug effectiveness during 5FU treatment. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-353. doi:1538-7445.AM2012-LB-353