(2-Cyclohexyl-2-oxoethyl)phosphonic Acid Dimethyl Ester-d11 is an intermediate in synthesizing NLG919-d10 (N630002). It is a isotope labelled analog of NLG919 (N630000). NLG919 is a potent indoleamine-2,3-dioxygenase (IDO) pathway inhibitor and is suitable for the treatment of immunosuppression associated with cancer.