Lincoln J Ombelets

Medulloblastoma is one of the most common malignant brain tumors of children, and 30% of medulloblastomas are driven by gain-of-function genetic lesions in the Sonic Hedgehog (SHH) signaling pathway. EYA1, a haloacid dehalogenase phosphatase and transcription factor, is critical for tumorigenesis and proliferation of SHH medulloblastoma (SHH-MB). Benzarone and benzbromarone have been identified as allosteric inhibitors of EYA proteins. Using benzarone as a point of departure, we developed a panel of 35 derivatives and tested them in SHH-MB. Among these compounds, DS-1–38 functioned as an EYA antagonist and opposed SHH signaling. DS-1–38 inhibited SHH-MB growth in vitro and in vivo, showed excellent brain penetrance, and increased the lifespan of genetically engineered mice predisposed to fatal SHH-MB. These data suggest that EYA inhibitors represent promising …

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KRAS is the most frequently mutated oncogene found in pancreatic, colorectal, and lung cancers. Although it has been challenging to identify targeted therapies for cancers harboring KRAS mutations, KRASG12C can be targeted by small-molecule inhibitors that form covalent bonds with cysteine 12 (C12). Here, we designed a library of C12-directed covalent degrader molecules (PROTACs) and subjected them to a rigorous evaluation process to rapidly identify a lead compound. Our lead degrader successfully engaged CRBN in cells, bound KRASG12C in vitro, induced CRBN/KRASG12C dimerization, and degraded GFP-KRASG12C in reporter cells in a CRBN-dependent manner. However, it failed to degrade endogenous KRASG12C in pancreatic and lung cancer cells. Our data suggest that inability of the lead degrader to effectively poly-ubiquitinate endogenous KRASG12C underlies the lack of activity. We …