employed substantial pressure
liquid chromatography and mass spectrometry to show the presence of CNddC in hydrolysates 
of DNA isolated from cells following CNDAC treatment method, indicating that B elimination happens in intact cells. Eventually, it was demonstrated that all detectable CNddC was at the 3 terminus, offering evidence of the self strand breaking action of CNDAC nucleotide following incorporation into DNA. Therefore, the mechanism of action of CNDAC is distinct from other clinically energetic nucleosides. To obtain oral bioavailability, CNDAC was derivatized with a palmitoyl group at the N4 exocyclic amine this was designated as CS 682 by Sankyo Co. , Ltd. , Tokyo, Japan, the unique pharmaceutical sponsor. The fatty acid side chain on the N4 group of the cytosine moiety improves oral bioavailability and reduces inactivation by deamination.
Subsequently, after Cyclacel Pharmaceuticals, Berkeley Heights, NJ, USA, assumed clinical advancement of the compound in 2003, this was re designated initially as CYC 682, and hts screening subsequently as sapacitabine. Therefore, all the names indicate the exact same chemical entity, but recognize the respective sources of compound. As is the case with other deoxycytidine analogs, for instance, ara C, gemcitabine, research in cell lines demonstrated that Factot Xa is phosphorylated to the monophosphate by deoxycytidine kinase, albeit with reasonably poor performance compared with dCyd or the other analogs. Cells lacking this enzyme had been significantly resistant to the analog. Also, CNDAC is a substrate for deamination by cytidine deaminase, which generates the inactive uracil derivative CNDAU. The triphosphate accumulates in a concentration dependent manner, and competes with dCTP for incorporation into DNA.
CNDAC was demonstrated to have potent antitumor activity in preclinical research. The antiproliferative results of CNDAC in terms of IC50 values have been much more potent than these observed with ara C. The analog showed broad spectrum activity against tumor cell lines and also in the P388 leukemia mouse model. CNDAC was much more effective than cytarabine in some human tumor cell lines derived from lung, stomach and osteosarcoma and showed superb activity against tumor cell lines refractory to cytarabine. Even so, the orally administered prodrug was more powerful against human tumor xenografts than CNDAC or 5 fluorouracil. It was also productive against several human organ tumor xenografts over a wider dose variety and with fewer toxicities.
CS 682 was also efficient against P388 human leukemia cells resistant to a variety of other agents which includes mitomycin C, vincristine, 5 fluorouracil and cisplatin in syngeneic mice. Employing highresolution magnetic imaging, significant-scale peptide synthesis Wu et al. demonstrated that CS 682 delayed the growth of orthotopically implanted AX3488 liver tumors, and also delayed their meta static behavior. The metastatic behavior of an orthotopic model of pancreatic carcinoma was delayed, and all round survival of the mice was prolonged by CS 682. A liposomal formulation of CNDAC showed activity against Meth A sarcoma bearing mice when injected intravenously. The antitumor activity of the liposomally encapsulated formulation was more potent than that of the parent drug cyclic peptide synthesis suggesting that the liposomal preparation enhanced therapeutic efficacy whilst at the very same time minimizing toxicity.
Sapacitabine in mixture with histone deacetylase inhibitors induced an boost in apoptosis and demonstrated considerable benefit compared with the single agent treatment options both in vitro and in xenografts of the MV4 11 myeloid leukemia. The encouraging actions in preclinical models offered rationale for clinical trials of the bioavailable prodrug formulation.