TTT-28 is a synthesized thiazole-valine peptidomimetic, a novel selective inhibitor of ABCB1 (P-gp/MDR1) with high efficacy and low toxicity, which reverses the ATP-binding cassette sub-family B member 1 ( ABCB1 )-mediated multidrug resistance (MDR) by selectively blocking the efflux function of ABCB1. In Vitro TTT-28 (0-100 μM; 72 hours) reverses ABCB1-mediated MDR in drug selected SW620/Ad300 cells and transfected HEK293/ABCB1 cells; the IC 50 s of TTT-28 in CCD-18Co, SW620 and SW620/Ad300 cells are 213.4±11.0 μM, 89.4±3.9 μM and 92.0±5.0 μM, respectively. TTT-28 (10 μM; 2 hours) raises the ABCB1-mediated MDR and increased the accumulation of [ 3 H]-paclitaxel in ABCB1 overexpressing cells. TTT-28 (10 μM; 0-72 hours) does not interfer with the expression level and localization of ABCB1, it results from blocking the efflux function of ABCB1. TTT-28 (0-40 μM; 2 hours) interacts at the drug-substrate-binding site and actives the ATPase activity of ABCB1 in a concentration-dependent fashion. MCE has not independently confirmed the accuracy of these methods. They are for reference only. Cell Viability AssayCell Line: SW620 cells, SW620/Ad300 cells Concentration: 0.1 μM, 1 μM, 10 μM, 100 μM Incubation Time: 72 hours Result: Decreased the resistance fold of ABCB1 substrates (Paclitaxel, Doxorubicin, Vincristine) in SW620/Ad300 cells compared to SW620 cells. In Vivo TTT-28 (deliver orally; 30 mg/kg; every 3 rd day; 18 days) potentiates the anticancer activity of paclitaxel due to its inhibitory effect on the efflux function of ABCB1, it enhances the inhibitory effect of paclitaxel on the growth of SW620/Ad300 tumor and promoted apoptosis . MCE has not independently confirmed the accuracy of these methods. They are for reference only. Animal Model: 5-10 week Male athymic NCR (nu/nu) nude mice ABCB1 overexpressing tumor xenograft model with SW620/Ad300 cells Dosage: 30 mg/kg Administration: Deliver orally; every 3rd day; 18 days Result: Lead to higher intratumoral accumulation of paclitaxel in tumors. Form:Solid