Abstract 4839: Design of a Rofecoxib-Combretastatin hybrid drug that exerts highly potent antimicrotubule, anti-angiogenesis properties and Cox-2 inhibition both in cell culture and xenograft models

Given the molecular complexity of cancers, including the extreme heterogeneity in their genetic makeup, their plasticity, innate or acquired resistance to anticancer drugs, there is an increasing need for the development of single molecule drugs that can effectively and simultaneously impact two or more targets simultaneously triggering multiple cytocidal events in synergy to obtain superior chemosensitivities and prevent resistance. Therefore, we developed a hybrid drug by combining the Cox-2 selective NSAID rofecoxib with a trimethoxy aryl group found in combretastatin A4 (CA4) which is a potent antimicrotubule and anti-angiogenesis agent. Two of methoxy groups of the CA4, were, however, replaced with iodine in the hybrid drug named KSS-19. The structural design of KSS-19 also preserved the CA4 nucleus in the cis-configuration and prevented its isomerization to the biologically inactive trans-form. KSS-19 was highly potent in specifically killing the tumor cells of various human cancer types at 2-50 nM range. These included the colon (HT29, HCT116), breast (MDA-MB-231, SK-BR-3), lung (A549, H1299), brain (SF188, GBM10, GBM6), pancreas (MIA-PaCa-2) and fibrosarcoma (HT1080). Particularly significant was that KSS-19 was 100 time more potent than CA4 against the HT29 colon cancer cells. Various biochemical and immunocytochemical assays revealed that KSS-19 retained the microtubule disrupting effects of CA4, including microtubule depolymerization, the formation of aberrant mitotic spindles, and G2/M phase arrest. The hybrid drug also inhibited the polymerization of purified tubulins in vitro. Furthermore, KSS-19 potently inhibited the formation of tubes in three-dimensional cultures of the HUVEC (Human umbilical Vein Cell) drastically decreasing the tube length and junctions at 250 nM concentration. The cancer cell migration /invasion, determined by transwell assays were also inhibited, and the inhibition was accompanied by increased E-cadherin levels through NF-kB/Snail pathway. The basal and LPS-activated levels of Cox-2 in tumor cell lines, as determined by western blot and immunofluorescence assays were highly suppressed by KSS-9. In a mouse xenograft model using HT-29 colon cancer cells, KSS19 as a single agent (75 mg/kg) significantly inhibited the tumor growth; the intratumoral levels of Cox-2 and in vivo angiogenesis were also markedly downregulated without any organ toxicities. Higher levels of cleaved caspase-3 and PARP proteins in the tumor suggested the priming of the apoptotic pathways. In conclusion, our results indicate that KSS-19 represents a new prototype chemo drug with multiple mechanisms of action. Such hybrid anticancer drugs merit further development (supported by CPRIT grant RP130266 to KSS). Citation Format: Surendra R. Punganuru, Hanumantha Rao Madala, Constantinos Mikelis, Kalkunte S. Srivenugopal. Design of a Rofecoxib-Combretastatin hybrid drug that exerts highly potent antimicrotubule, anti-angiogenesis properties and Cox-2 inhibition both in cell culture and xenograft models. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4839.