Idelalisib GS-563117 metabolite

Idelalisib GS-563117 metabolite is a pharmacologically active degradation product arising from oxidative metabolism of the parent drug, characterized by a hydroxylated pyrimidine core and a retained piperazine-linked phosphonate moiety. This impurity exhibits a C-7 hydroxyl substitution and loss of the 4-amino-2-aminopyrimidine side chain, resulting in reduced kinase inhibitory activity. Structurally, it maintains the 2-amino-6-chloro-9-isopropylpurine scaffold but with a truncated N1-piperazinyl group. This compound serves as a critical HPLC reference standard for quantifying metabolic degradation in stability studies of Idelalisib drug substances.