INY-06-061

INY-06-061 demonstrates potent and rapid degradation of ERK5 (MAPK7) in cells at sub-micromolar concentrations, but not at supra-micromolar concentrations due to hook effect. Selectivity for ERK5 was shown through cell-free kinome screening and global proteomics profiling analysis in cells. INY-06-089 can serve as an inactive negative control for INY-06-061. Mechanism of action through the ubiquitin-proteasome system was verified using proteasomal and neddylation inhibitors, and indirect evidence of target engagement through cellular competitive binding assays using an ERK5 ligand. Anti-proliferative activity was tested in a panel of 750 cell lines, ERK5-dependent cancer cell lines, and human endothelial cells with little or no effect on proliferation and inflammatory response, indicating a phenotypic discrepancy between genetic knockdown and INY-06-061-induced degradation of ERK5.

INY-06-061 is a potent ERK5 degrader that is well profiled, showing high binding affinity to the target and also dependency on ubiquitin-proteasome system. Complete data on Dmax is not yet established, as well as the time course of the degradation. However, the experiments conducted prove the specific degradation of ERK5 - though it does not stop cell proliferation in cancer models.