MD-4251

Potency assay, off target (cells): MD-4251 was evaluated for GSPT1, IKZF1/3, and CK1α, a number of known neo-substrates for cereblon ligands in Western blot after 2 h treatment, and had no effect on the levels of GSPT1 and IKZF3 and only had a modest effect on IKZF1 and CK1α.

Potency assay, off target (cells): Cellular degradation selectivity of MD-4251 was evaluated via an unbiased proteomics analysis. MD-4251 induced robust upregulation of p53 protein (TP53 gene product), MD-4251 also increased the levels of three other proteins, namely DSC1 (Desmocollin-1), NBEA (neurobeachin), and CASP14 (Caspase-14). Due to the low level of MDM2 protein, depletion of MDM2 protein was not detected in this proteomics experiment and no protein was reduced by more than 2-fold.