NLG919 is a novel small-molecule IDO-pathway inhibitor. NLG919 potently inhibits this pathway in vitro and in cell-based assays. It is orally bioavailable and has a favorable pharmacokinetic and toxicity profile. In mice, a single oral administration of NLG919 reduces the concentration of plasma and tissue Kyn by ∼ 50%. Using IDO-expressing human monocyte-derived DCs in allogeneic MLR reactions, NLG919 potently blocked IDO-induced T cell suppression and restored robust T cell responses with an ED50=80 nM. Similarly, using IDO-expressing mouse DCs from tumor-draining lymph nodes, NLG919 abrogated IDO-induced suppression of antigen-specific T cells (OT-I) in vitro. In vivo, in mice bearing large established B16F10 tumors, administration of NLG919 markedly enhanced the anti-tumor responses of naïve, resting pmel-1 cells to vaccination with cognate hgp100 peptide plus CpG-1826 in IFA

ISOMETHEPTENE, (R)- is an antimigraine drug candidate, which development was discontinued in 2016. It is a potent agonist of the imidazoline-1-receptor.

Nitroarginine (LNNA), an analog of L-arginine, is a competitive inhibitor of nitric oxide synthase which has been shown to prevent glutamate toxicity. Nitroarginine has been experimentally tested for its ability to prevent ammonia toxicity and ammonia-induced alterations in brain energy and ammonia metabolites. The Kd value (k(off)/k(on)) of bovine brain cNOS for LNNA was 15 nM. In contrast to the potent and slow onset of LNNA inhibition of brain cNOS, LNNA inhibition of inducible mouse macrophage NOS (iNOS) was weaker (Ki = 4.4 uM) and rapidly reversible. Thus, LNNA was a 300-fold more potent inhibitor of bovine brain cNOS than mouse macrophage iNOS. By inhibiting nitric oxide synthase LNNA causes the selective reduction of blood flow to tumor cells. Despite the potential of LNNA to function as an adjuvant in cancer therapies, its poor solubility and stability have hindered the development of an injectable formulation of LNNA that is suitable for human administration.