LCL161 is a SMAC mimetic, an IAP antagonist with oral activity that inhibits XIAP (IC50=35 nM) in HEK293 cells and also inhibits cIAP1 (IC50=0.4 nM) in MDA-MB-231 cells. LCL161 has potential antitumor activity.

XIAP (HEK293 cells):35 nM, CIAP1 (MDA-MB-231 cells):0.4 nM

CYP3A activity is assessed using the probe reactions, midazolam-1′-hydroxylation and testosterone 6β-hydroxylation. For reversible inhibition, incubations (37°C, 10 min) are composed of (final concentrations): potassium phosphate buffer (100 mM, pH 7.4), β-NADPH (1 mM), magnesium chloride (5 mM), microsomal protein (0.025 mg/mL), probe substrate (1 μM midazolam or 25 μM testosterone), LCL161 (0, 0.5, 1, 5, 10, 25, 50, or 100 μM) and organic solvent (0.2% acetonitrile for midazolam, 0.2% methanol for testosterone). After a 3-minute preincubation, the reactions are initiated by addition of β-NADPH and terminated by addition of acetonitrile (two volumes). Reactions are previously shown to be linear with respect to time and protein concentration (results not shown) with midazolam and testosterone turnover of 8.7±1.3% (n=3) and 2.6±0.20%, respectively. Formation of 1′-hydroxymidazolam and 6β-hydroxytestosterone is determined by LC-MS/MS as described below[3].

In vitro testing is performed using DIMSCAN (Only for Reference)