Antisense phosphorothioate oligodeoxyribonucleotide targeted against ICAM-1: synthetic and biological characterization of a process-related impurity formed during oligonucleotide synthesis

A phosphorothioate-linked oligonucleotide bearing a 3'-terminal phosphorothioate monoester has been synthesized and characterized. This oligonucleotide has been identified as a process-related impurity formed during synthesis of ISIS 2302. Biological properties of the compound have been determined. Based on these data, it can be concluded that this species (3'-TPT) has biological properties similar to parent drug.