OSI-906 (Linsitinib (OSI-906)) is an orally bioavailable small molecule inhibitor of the insulin-like growth factor 1 receptor (IGF-1R) with potential antineoplastic activity. Linsitinib selectively inhibits IGF-1R, which may result in the inhibition of tumor cell proliferation and the induction of tumor cell apoptosis. Overexpressed in a variety of human cancers, IGF-1R stimulates cell proliferation, enables oncogenic transformation, and suppresses apoptosis.

IGF-1R:35 nM, IRR:75 nM, Insulin receptor:75 nM

Linsitinib通过与C-helix的相互作用使目标蛋白质呈现中间构象，抑制IGF-1R自磷酸化以及下游信号蛋白Akt、ERK1/2和S6激酶的激活，其IC50值为0.028至0.13μM。Linsitinib在肝微粒体中表现出良好的代谢稳定性，并在1μM浓度完全抑制IR和IGF-1R的磷酸化。此外，Linsitinib还能抑制包括非小细胞肺癌和结直肠癌（CRC）肿瘤细胞系在内的多种肿瘤细胞系的增殖，EC50值为0.021至0.810μM。[1]

Linsitinib在IGF-1R驱动的异种移植小鼠模型中抑制肿瘤生长，75 mg/kg剂量下实现100%的肿瘤生长抑制(TGI)和55%的肿瘤退缩，25 mg/kg剂量下实现60%的TGI且无肿瘤退缩。Linsitinib在狗、大鼠和小鼠体内展示不同的自身清除半衰期，分别为1.18小时、2.64小时和2.14小时。在雌性Sprague-Dawley大鼠和雌性CD-1小鼠中，Linsitinib不同单一剂量每日一次给药，显示其最大速率(Vmax)与剂量不成比例。12天给药后，25 mg/kg剂量的Linsitinib使血糖水平升高。在IGF-1R驱动的全长人IGF-1R(LISN)异种移植小鼠模型中，75 mg/kg单次剂量的Linsitinib在4至24小时内达到IGF-1R磷酸化的最大抑制（80%），血浆化合物浓度为26.6-4.77 μM。[1] 60 mg/kg剂量的Linsitinib在NCI-H292异种移植小鼠中单次给药后，在体内2、4和24小时抑制葡萄糖摄取，并抑制NCI-H292异种移植小鼠模型中的肿瘤生长。[2]

Protein kinase biochemical assays: Protein kinase assays are either performed in-house by ELISA-based assay methods (IGF-1R,IR,EGFR and KDR) or at Upstate Inc.by a radiometric method with ATP at 100 μM concentration.In-house ELISA assays use poly(Glu:Tyr) as the substrate bound to the surface of 96-well assay plates and phosphorylation is detected using an antiphosphotyrosine antibody conjugated to horseradish peroxidase.The bound antibody is quantified using ABTS as the peroxidase substrate by measuring absorbance at 405 / 490 nm.All assays use purified recombinant kinase catalytic domains.Recombinant enzymes of human IGF-1R or EGFR are expressed as an NH2-terminal glutathione S-transferase fusion protein in insect cells and are purified in house.IC50 values are determined from the sigmoidal dose–response plot of percent inhibition versus log10 compound concentration.A minimum of three measurements,performed in duplicate,are carried out with in-house assays unless otherwise indicated.OSI-906 at a concentration of 1 μM is profiled versus a panel of kinases using the ProfilerProTM Kinase Selectivity Assay Kit.

For assays of cell proliferation, cells are seeded into 96-well plates in appropriate media containing FCS 10% and incubated for 3 days in the presence of OSI-906 at various concentrations. Inhibition of cell growth is determined by luminescent quantitation of intracellular ATP content using CellTiterGlo. Data is presented as a fraction of maximal proliferation, calculated by dividing the cellular density in the presence of varying concentrations of OSI-906 by the cellular density of control cells treated with vehicle (DMSO) only.(Only for Reference)