Subsequently, Hanaoka et al. utilised substantial stress
liquid chromatography and mass spectrometry to show the presence of CNddC in hydrolysates 
of DNA isolated from cells after CNDAC remedy, indicating that B elimination happens in intact cells. Finally, it was demonstrated that all detectable CNddC was at the 3 terminus, providing evidence of the self strand breaking action of CNDAC nucleotide following incorporation into DNA. As a result, the mechanism of action of CNDAC is distinct from other clinically active nucleosides. To attain 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 original pharmaceutical sponsor. The fatty acid side chain on the N4 group of the cytosine moiety improves oral bioavailability and minimizes inactivation by deamination.
Subsequently, right after Cyclacel Pharmaceuticals, Berkeley Heights, NJ, USA, assumed clinical advancement of the compound in 2003, this was re designated at first as CYC 682, and Aspect Xa subsequently as sapacitabine. Hence, all the names indicate the identical chemical entity, but identify the respective sources of compound. As is the situation with other deoxycytidine analogs, for instance, ara C, gemcitabine, reports in cell lines demonstrated that hts screening is phosphorylated to the monophosphate by deoxycytidine kinase, albeit with comparatively poor effectiveness compared with dCyd or the other analogs. Cells lacking this enzyme were tremendously 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 studies. The antiproliferative results of CNDAC in terms of IC50 values had been far more strong than individuals observed with ara C. The analog showed broad spectrum activity against tumor cell lines and also in the P388 leukemia mouse model. CNDAC was far more effective than cytarabine in some human tumor cell lines derived from lung, abdomen and osteosarcoma and showed outstanding activity against tumor cell lines refractory to cytarabine. Nevertheless, the orally administered prodrug was much more strong against human tumor xenografts than CNDAC or 5 fluorouracil. It was also effective against numerous human organ tumor xenografts in excess of a wider dose variety and with fewer toxicities.
CS 682 was also productive against P388 human leukemia cells resistant to a selection of other agents which includes mitomycin C, vincristine, 5 fluorouracil and cisplatin in syngeneic mice. Employing highresolution magnetic imaging, oligopeptide synthesis Wu et al. demonstrated that CS 682 delayed the development of orthotopically implanted AX3488 liver tumors, and also delayed their meta static conduct. The metastatic conduct of an orthotopic model of pancreatic carcinoma was delayed, and total 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 much more strong than that of the parent drug fluorescent peptides suggesting that the liposomal preparation enhanced therapeutic efficacy whilst at the very same time minimizing toxicity.
Sapacitabine in combination with histone deacetylase inhibitors induced an increase in apoptosis and demonstrated substantial advantage compared with the single agent treatment options both in vitro and in xenografts of the MV4 11 myeloid leukemia.