The effects of 6-mercaptopurine nucleotide derivatives on the growth and survival of 6-mercaptopurine-sensitive and -resistant cell culture lines

Synthesis and anti-proliferative activity of pyridine O-galactosides and 4-fluorobenzoyl analogues

Pyridine O-galactosides 3, 4, and 2-(4′-fluorobenzoyloxy)pyridine derivatives 5 were prepared by simple nucleophilic substitution reactions. These nucleosides were studied as anti-proliferating agents of human promyelotic leukemia (HL-60) cells. Compound 5a shows the highest anti-proliferative activity (77% at 100 μm) among the synthesized compounds.

Selective toxicity of deoxyadenosine analogues in human melanoma cell lines

The in vitro toxicities of 19 analogues of deoxyadenosine were tested using a panel of human melanoma cell lines including two lines sensitive to deoxyadenosine and deoxyinosine. The 2-fluoro-, 2-chloro-, 2-bromo- and 2-amino-8-aza derivatives were the most toxic and showed selectivity against deoxyadenosine-sensitive cells. 2-Bromodeoxyadenosine (BrdAdo) and its 5'-phosphate were less potent than the chloro compound but showed the greatest selectivity. In further studies of BrdAdo a third sensitive melanoma line was identified of the eight tested. A treatment time of 24 hr or more was required to develop toxicity to BrAdo; this could be prevented by deoxycytidine or cytidine added to the medium but not by other nucleosides. Flow cytometry showed that BrdAdo blocked cells in the G1 and S phases of the cell cycle. DNA synthesis as judged by thymidine incorporation was rapidly inhibited by BrdAdo to an extent which reflected the sensitivity of the particular cell line; RNA synthesis was less affected. Exposure to BrdAdo for 48 hr induced breaks in the preformed DNA of sensitive but not resistant cells. The results suggest that the toxicity of BrdAdo is associated with prolonged inhibition of DNA synthesis and subsequent DNA fragmentation.

Large interindividual variations in the pharmacokinetics of oral 6-mercaptopurine in maintenance therapy of children with acute leukaemia and non-Hodgkin lymphoma

The concentrations of 6-mercaptopurine were studied in plasma and red blood cells from 10 children with acute leukaemia or non-Hodgkin lymphoma receiving oral maintenance therapy. The doses varied between 25 and 79 mg/m2 body surface once daily. Large interindividual differences were found in the concentrations both in plasma and in red blood cells. There was no clear relationship between the dose administered and the concentrations obtained. However, in each patient the concentrations in plasma and in red blood cells were very similar. In most patients, the peak concentrations were reached 1-2 hours after dose intake and the concentrations then declined with half-lives less than 1 hour. Further studies are necessary to evaluate the potential value of drug level monitoring in optimizing treatment with oral 6-mercaptopurine.