1. Mapping the degradable kinome provides a resource for expedited degrader development.
Donovan, K.A., Ferguson, F.M., Bushman, J.W., Eleuteri, N.A., Bhunia, D., Ryu, S., Tan, L., Shi, K., Yue, H., Liu, X. and Dobrovolsky, D., 2020. Cell, 183(6), pp.1714-1731.
Targeted protein degradation (TPD) refers to the use of small molecules to induce ubiquitin-dependent degradation of proteins. TPD is of interest in drug development, as it can address previously inaccessible targets. However, degrader discovery and optimization remains an inefficient process due to a lack of understanding of the relative importance of the key molecular events required to induce target degradation. Here, we use chemo-proteomics to annotate the degradable kinome. Our expansive dataset provides chemical leads for ~200 kinases and demonstrates that the current practice of starting from the highest potency binder is an ineffective method for discovering active compounds. We develop multitargeted degraders to answer fundamental questions about the ubiquitin proteasome system, uncovering that kinase degradation is p97 dependent. This work will not only fuel kinase degrader discovery, but also provides a blueprint for evaluating targeted degradation across entire gene families to accelerate understanding of TPD beyond the kinome.
2. Selective CDK6 degradation mediated by cereblon, VHL, and novel IAP-recruiting PROTACs.
Anderson, N.A., Cryan, J., Ahmed, A., Dai, H., McGonagle, G.A., Rozier, C. and Benowitz, A.B., 2020. Bioorganic & Medicinal Chemistry Letters, 30(9), p.127106.
Inhibitors of CDK4 and CDK6 have emerged as important FDA-approved treatment options for breast cancer patients. The properties and pharmacology of CDK4/6 inhibitor medicines have been extensively profiled, and investigations into the degradation of these targets via a PROTAC strategy have also been reported. PROTACs are a novel class of small-molecules that offer the potential for differentiated pharmacology compared to traditional inhibitors by redirecting the cellular ubiquitin-proteasome system to degrade target proteins of interest. We report here the preparation of palbociclib-based PROTACs that incorporate binders for three different E3 ligases, including a novel IAP-binder, which effectively degrade CDK4 and CDK6 in cells. In addition, we show that the palbociclib-based PROTACs in this study that recruit different E3 ligases all exhibit preferential CDK6 vs. CDK4 degradation selectivity despite employing a selection of linkers between the target binder and the E3 ligase binder.
