Discovery of a Potent Degrader for Fibroblast Growth Factor Receptor 1/2

Abstract Aberrant activation of FGFR signaling occurs in many cancers, and ATP‐competitive FGFR inhibitors have received regulatory approval. Despite demonstrating clinical efficacy, these inhibitors exhibit dose‐limiting toxicity, potentially due to a lack of selectivity amongst the FGFR family and are poorly tolerated. Here, we report the discovery and characterization of DGY‐09‐192, a bivalent degrader that couples the pan‐FGFR inhibitor BGJ398 to a CRL2 VHL E3 ligase recruiting ligand, which preferentially induces FGFR1&2 degradation while largely sparing FGFR3&4. DGY‐09‐192 exhibited two‐digit nanomolar DC 50 s for both wildtype FGFR2 and several FGFR2‐fusions, resulting in degradation‐dependent antiproliferative activity in representative gastric cancer and cholangiocarcinoma cells. Importantly, DGY‐09‐192 induced degradation of a clinically relevant FGFR2 fusion protein in a xenograft model. Taken together, we demonstrate that DGY‐09‐192 has potential as a prototype FGFR degrader.