Synthesis, Characterization, and In Vitro and In Vivo Evaluations of 4-(N)-Docosahexaenoyl 2′, 2′-Difluorodeoxycytidine with Potent and Broad-Spectrum Antitumor Activity

Abstract

In this study, a new compound, 4-(N)-docosahexaenoyl 2′, 2′-difluorodeoxycytidine (DHA-dFdC), was synthesized and characterized. Its antitumor activity was evaluated in cell culture and in mouse models of pancreatic cancer. DHA-dFdC is a poorly soluble, pale yellow waxy solid, with a molecular mass of 573.3 Da and a melting point of about 96°C. The activation energy for the degradation of DHA-dFdC in an aqueous Tween 80–based solution is 12.86 kcal/mol, whereas its stability is significantly higher in the presence of vitamin E. NCI-60 DTP Human Tumor Cell Line Screening revealed that DHA-dFdC has potent and broad-spectrum antitumor activity, especially in leukemia, renal, and central nervous system cancer cell lines. In human and murine pancreatic cancer cell lines, the IC50 value of DHA-dFdC was up to 105-fold lower than that of dFdC. The elimination of DHA-dFdC in mouse plasma appeared to follow a biexponential model, with a terminal phase t1/2 of about 58 minutes. DHA-dFdC significantly extended the survival of genetically engineered mice that spontaneously develop pancreatic ductal adenocarcinoma. In nude mice with subcutaneously implanted human Panc-1 pancreatic tumors, the antitumor activity of DHA-dFdC was significantly stronger than the molar equivalent of dFdC alone, DHA alone, or the physical mixture of them (1:1, molar ratio). DHA-dFdC also significantly inhibited the growth of Panc-1 tumors orthotopically implanted in the pancreas of nude mice, whereas the molar equivalent dose of dFdC alone did not show any significant activity. DHA-dFdC is a promising compound for the potential treatment of cancers in organs such as the pancreas.

Preclinical Evaluation of the Short-Term Toxicity of 4-(N)-Docosahexaenoyl 2´, 2´- Difluorodeoxycytidine (DHA-dFdC)

“…DHA-dFdC was synthesized following our previously reported conjugation scheme (32). The purity of the resultant DHA-dFdC was confirmed by NMR and Mass Spectrum analyses.…”

“…Previously, in an effort to exploit the antitumor activity of both gemcitabine and DHA, we synthesized a new compound, DHA-dFdC, by covalently conjugating DHA to dFdC at the 4-N position of dFdC (32). DHA-dFdC is a pale yellow waxy solid with a melting point of 96º C. It is poorly soluble in water (i.e.…”

“…DHA-dFdC is a pale yellow waxy solid with a melting point of 96º C. It is poorly soluble in water (i.e. 25.2 ± 11.2 μg/ml) and has a log P value of 2.2 ± 0.3 (32). DHA-dFdC has potent cytotoxicity against a broad-spectrum of human and mouse tumor cell lines and showed significant antitumor activity in several mouse models of pancreatic cancer, including Kras-Ink4a genetically-modified mice and nude mice with orthotopically implanted human Panc-1 tumor cells (32).…”

“…25.2 ± 11.2 μg/ml) and has a log P value of 2.2 ± 0.3 (32). DHA-dFdC has potent cytotoxicity against a broad-spectrum of human and mouse tumor cell lines and showed significant antitumor activity in several mouse models of pancreatic cancer, including Kras-Ink4a genetically-modified mice and nude mice with orthotopically implanted human Panc-1 tumor cells (32). Importantly, in both tumor cells in culture and in animals, DHA-dFdC is significantly more effective than the molar equivalent DHA and dFdC physically mixed (32), suggesting a unique mechanism of antitumor activity by the DHA-dFdC conjugate.…”

“…DHA-dFdC has potent cytotoxicity against a broad-spectrum of human and mouse tumor cell lines and showed significant antitumor activity in several mouse models of pancreatic cancer, including Kras-Ink4a genetically-modified mice and nude mice with orthotopically implanted human Panc-1 tumor cells (32). Importantly, in both tumor cells in culture and in animals, DHA-dFdC is significantly more effective than the molar equivalent DHA and dFdC physically mixed (32), suggesting a unique mechanism of antitumor activity by the DHA-dFdC conjugate. In the present study, we tested the short-term toxicity of DHA-dFdC in healthy DBA/2 mice by identifying its RD-MTD, a lethal-RD, and the major organ(s) and blood and serum parameters affected by DHA-dFdC at the lethal-RD.…”