Ribociclib hydrochloride

LEE011, as dual CDK4/CDK6 inhibitor, significantly inhibits the growth of 12 of 17 neuroblastoma cell lines with mean IC50 of 307 nM. The growth inhibition of neuroblastoma cell lines is primarily cytostatic and is mediated by a G1 cell-cycle arrest and cellular senescence. ^[2]

A panel of neuroblastoma cell lines, selected based upon prior demonstration of substrate adherent growth, is plated in triplicate on the Xcelligence Real-Time Cell Electronic Sensing system and treated 24 hours later with a four-log dose range of inhibitor or with a dimethyl sulfoxide (DMSO) control. Cell indexes are monitored continuously for ~100 hours, and IC50 values are determined as follows: growth curves are generated by plotting the cell index as a function of time and are normalized to the cell index at the time of treatment for a baseline cell index of 1. The area under the normalized growth curve from the time of treatment to 96 hours posttreatment is then calculated using a baseline area of 1 (the cell index at the time of treatment). Areas are normalized to the DMSO control, and the resulting data are analyzed using a nonlinear log inhibitor versus normalized response function. All experiments are repeated at least once.

LEE011 (200 mg/kg daily, p.o.) significantly causes tumor growth delay in mice harboring the BE2C or 1643 xenografts with no weight loss or other signs of toxicity. ^[2]